Ill keep updating until i get it. Its increased to 9,2-9,3 liter/100 km (30 mpg) from the normal 5-6 liter/100 km (50 mpg). You'll need to take off the intake assembly all the way to the carb, then loosen the rubber coupling (between the carb and cylinder head). It was a wreck when I got it (although it just about ran), but now the valves have been lapped in and Ive replaced the ignition circuit theres a strong spark at the plug. If you had that much fuel in the crankcase, the float became stuck open due to debris of worn float needle. Very appreciated. With the carb off or even still on, you only need to remove the 17mm nut on the bottom cover to access the jets. Another thing that you can play with is ignition timing. Did you snych the carbs? The quad has a full exhaust on it and the main is sized correctly. Or what else could be the problem? Any suggestions from anyone to help me resolve this high RPM performance problem? If the plugs are not fouled dont bother changing them until you have it running much better.
However, if this is something new, check for exhaust & vacuum leaks, as they can cause this as well. If you go back to the link I provided on tuning cutaway, there is a graph from Mikuni that shows each size changes fuel flow by 10%.
It's called a "stone" fuel filter in that you'll see what looks like a golden stone inside the filter housing. Cool. The main jet is responsible for 3/4 to full throttle position running. After idle, number 4 plug is petrol wet when pulled. I have the same xs750 77 triple you have worked on.
Both carbs should be tuned to the same number of turns out on the pilot fuel or air screw. I almost always have to choke it to start it even after its warm. Should I put in new plugs? How many turns out for smoothest and highest peak RPM with the 17.5? Its way loud and if the mechanic tuned to proper specs, somethings off cause my old one never idled like that.
A rich condition will cause the engine to sputter, and emit black smoke from exhaust. Gonna order online so will take a week or so but Ill let you guys know when I get it put together. hi i have a yamaha grizzly 660 2004 what causes it to back fire when i let up on the throttle after driving at about 60 -80 km hr please and thankyou. Keep increasing until fuel screws net you 3 turns out for peak idle RPM. I reset mixture screws after the change it smoothest idle was atleast obtained. But the spark plug is minor lean. Any ideas or suggestions would be greatly appreciated.
Hi, I own a 1986 Yamaha fazer. Take carb apart and verify pilot jet is clean. For a better experience, please enable JavaScript in your browser before proceeding.
If not, I dont know what else I can do. How it sounds below:-, http://vid1277.photobucket.com/albums/y493/jgl9/yammissfire_zps2db14cb6.mp4. Try the the 4 stroke needle jet and report back. The carbs are off of a XR600R using all the XL600R air box and exhaust. So next day it sits over night and i try no choke. A pilot air screw will be made of brass, gold in color, and will have a blunt tip compared to a pilot fuel screw. I mean absolutly perfect.until i started moving and temp dropped to 160-170 where it normally runs and boom stumbling and studdering like crazy so bad a fe2 times off the take off i thought it was gunna die out completely. Then repeat for the other cyl. and fuel screw 2.75 out. The ones for the 4-stroke appear to have larger side holes. Engine begins to sputter as you increase throttle position to full throttle. I know this should be a little hard to say, but how much of a change does one usually go with the cutaways, considering I have the 45 and the others being 40, 50 and 55? Based on your video, I would guess that the pilot screw is too rich. To lower the idle, the slide in carburetor need to move down. The motor starts but dies in a second. : removing and dismantling the engine for internal inspection (rings, valves, timing chain setting, valve tappet clearance setting, etc.) What do you think? So I experimented with a 20% difference. Any suggestions to eliminate the bogging? Runs awsome from little over 1/4 to 3/4. If it starts fine w/o choke then its too rich.
OK. We need to get together soon. should i go to a higher jet i think its got a 150 main stock. To confirm that this part fits your vehicle, please choose a vehicle from the "My Garage" list OR enter your vehicles details below. I went from 122 mains to 125 mains and the color on the plug is headed in the right direction, light tan to pinkish. You have been a huge help btw. Thanks a lot ,now I can work from there!! It sputters until i get to the higher RPMs. I believe they are 40 mm flat slides and from what I read online it has one fuel screw and one air screw I could send you a picture if you still have the same #.
Its fit while engine on idle. The previous owner tried to make an attempt to do the same thing, but failed miserably. Also my temp is around 70s right now and altitude is 1400s above sea level, Sounds good. Hello, I have a 2004 Yamaha Raptor 350 with a stock carb and stock everything. Tusk, GYTR? Well heres the update. All you did is changed the mains which is 3/4 to full throttle fueling. Plus end of pipe was turning light greyish white. It almost seems like a misfire in a car.
It is sold by a company called factory pro. my 1977 cb 750k7 backfires thru the number 2 an3 cly. Probably overkill for this engine. Awesome! Once I fully close it, the bike shuts off even when the engine is warm. Your video and additional information helped me to find my solution to this issue. Thx. Martin,there are so many ATV's out there, it's impossible to know if your model had a inline fuel filter on it when it came from the factory. Your a life saver. I have a Chinese copy of a Honda XL125. They do a good job of filtering down to probably 20 microns or a little more of crud. I know that the stock air cleaner is very restrictive. Electric tape, RTV, etc..never seem to hold up. Hi I have a 1966 Yamaha 250cc model YDS3 that I am restoring to running condition the needle and seats are bad and leaks fuel when not running do you know where I could get replacement needle and seat or a way to reconditioned the ones I have I am also looking for other items maybe you know someone that might have some parts or could help in my search, You should be able to order OEM parts: https://youtu.be/eqe59cINk7A, Your email address will not be published. grizzlycentral.com is not in any way affiliated with Yamaha Motor Company. I bet you will find that 1-2 sizes larger than stock is what the bike would want. Maybe its an electric valve that close main jet? Raise needles 1 clip position. Get back to me on what you have. You probably had a stuck float. Report back after test ride. Bought as a left over from a dealer this spring so its only had gas in it since June. The float levels are fine and I synced the carbs per your video. Since you can turn in all the way in and it will still run, I would recommend dropping pilot jet 3-4 sizes. So Im wondering if that would be opening that un-meatered hole and causing my stumble this whole time. A forum community dedicated to Yamaha YFZ owners and enthusiasts. I have not replaced the Air Cutoff Valve (ACV) yet. The hesitation, is it a bog (lean) or rich (sputter)? First time I did the top end and a screw backed out of the cam sprocket while driving falling into the crankcase and breaking the sprocket. When you remove the jet, it will be stamped with a number, indicating size. Hi Matthew, I have a 1980 Yamaha XS1100 Special with pods and aftermarket exhausts. The Fora platform includes forum software by XenForo, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada, grizzlycentral.com is an independent Yamaha enthusiast website owned and operated by VerticalScope Inc. So far I am impressed with handling and performance. So i was testing a few things here and there and find the throttle position s3nsors resistance tested way out of spec. The bike when it was sold in the us had a retarded timing to meet regulation. Honestly, I dont have much experience with TPSs. I mean enough to make it run perfect then like crap just like that. We have to determine if its too rich or lean. Almost like its lean on the main jets. As a first step Ill unscrew all 4 spark plugs and check the conditions. I have a Kawasaki zrx1200r with 36mm CVK carbs. Is the stall from a bog? Have you had these carbs apart? The jets came in tomorrow, but as it turned out, the 36 is still too big. It almost sounds like the tone of the exhaust has changed also.
To be honest is was a little better but still ran similarly. Every carburetor know to man will have a way to adjust the air fuel ratio at idle. Hey Matthew, finally got the jets. Thanks. As soon as the choke is on and want to start the bike , it wont start. Carb 3 main 128, pilot 42. Too much advance can cause bucking like you described. once it starts it idles for maybe 2-5 seconds and it dies, weve tried Usually, I would expect the clip to be one position lower than stock and the mains 1-2 sizes bigger than stock. I dont know what to do. The GYTR screws are $35 after all. But it was done at a way different altitude then where im at now. About 2 months ago I had the carbs cleaned due to a drop in fuel mileage, from 120 miles to about 85 miles.
I did exactly as u said and went a half turn out to compensate and now the only time it sputters is when trying to go like 5-10 mph which I would consider exceptable from where it was at. And when you say blip.is it a small blip? I am in Devon, UK and there is a lack of yamaha carb experts here! Trying a 1/4 turn more fuel tomorrow. Have you verified the pilot jet size in service manual? Carb 2 main 112, pilot 45. have proved by pulling plug lead on 4 and engine note still the same on idle. Once it is started, pry the cap/screw out, and you can access your mixture screw. Stock is 130 outer and 125 inner. My mixture is at 2 3/4 and if i go leaner it seems like the idle drops and isnt as smooth. It has a full yoshimura pipe k&n air filter and lid hot rods hot cams hi compression piston and possibly has been bored out also. The ATV's carburators work by "gravity feed" and ARE NOT under any pressure at all. https://howtomotorcyclerepair.com/how-to-tune-a-motorcycle-main-jet/. Id follow the carb mfg spec for float height and stick with that. My idle was below 1000 rpm when I made the fuel screw adjustment. So i held the throttle wide open and it turned and fired atleast. What did the instructions say to install? Im not noticing any change in oil level so im not thinking its hydrolocking from filling a cylinder with fuel.
People park their motorcycles outside, especially in the winter, with untreated bare metal interior, part-empty fuel tank causing the inside surface of the tank to rust. Why are you trying to lean it out so much? Straight in line 1600cc (97ci) with four (BCF) keihin carbs. Sounds like wah wah wah wah wah all the way down the street until I give it a little more gas. Thanks again. I cant gather whether you are rich or lean on pilot. JavaScript is disabled. No not really, just doesnt pick up quickly from first applying the throttle. What style carbs? I ended up at around 2.25-2.5 turns, engine runs smooth. What should I try? Privacy Statement - The other should be the air screw (assuming this is an air screw carb). Also, can you send me a link to the jet kit? The purpose of the images above is to illustrate the differences in the tip, which will indicates what the screw meters. The pod filters may or may not let more air in at idle. Are you going to move on to the needle and main? Hey I have a 99 Polaris sportsman 500.we bought it and we rebuilt the carburetor and now when we ride it after a while it doesn't have any power. raptorforum.com is not in any way affiliated with Yamaha Motor Company. What is your setup here? But if I got to full choke it idles better. If so, it might be a rich spot. new spark plug yes indeed. So i check my mixtures and they are at 2 1/4. I test drove it and it is still boggy/skippy when taking off from a stop. Thanks for the reply! Engine run idle on fuel screw 5 counterclockwise. I have to use the choke for cold start for 5 seconds and then everything works great. How to i adust the jet screw ,whether i want to turn clockwise or anti clockwise. I removed the spark arrestor from the stock exhaust and this caused my quad to backfire frequently. Do you feel like trading a beer for a diagnosis? a 87 LT250R QuadRacer, Im sure Ill have more questions for you since all of them are having The only issue Im still having is that the bike is quite prone to stalling when I add very little gas (as in from a standing start at a traffic light). The pilot is adjusted for max RPM and hopefully is in the 1-3 turns out range.
I know the bike is running rich for sure(throwing fuel out) and it has a off idle hesitation. So Im thinking that is a good sign. Sometimes bikes are very lean from the factory. I have dismantled and inspected the carburetor three times to check for other potential carburetor problems with jets and passages. The *fuelscrew* (not an airscrew) on the Keihin FCR-39 carb is at the engine-side of the floatbowl pointing straight down. Another test is to turn the choke partially on and then do another acceleration test. Problem is that on idle, runs OK, when i add more throtle its still ok. .but when i ride and had over 5K (5 and 6th gear) RPM, its almost dead. I have an update on the gsxr. Dynojet stage 1 kit, original airbox&filter, Mivv slipon muffler, new sparkplugs, pilot screw: 2,5 rounds. Also any modifications like exhaust or pods? Thank you for the information. Ive tried opening the pilot screws from 2 turns out to 4 turns out but still the stalling trying to rev off an idle. Not yet, just hoped that previous adjustments would work. I guess this bike just came mega lean from the get go but how didnt it hessitate when new?
I am currently tuning my carb and would greatly appreciate some guidance. Dont use any downward pressure since the screw may plunge down and the tip will break in body. For a better experience, please enable JavaScript in your browser before proceeding. The bike has aftermarket air pods and Vance and Hines exhaust. At WOT, vacuum is low, and you have a leak, so fuel delivery will suffer. I am not mechanically inclined and the mechanic that originally did the work in no longer in my area. Refresh your browser window to try again. When you buy through links on our site, we may earn an affiliate commission.Copyright ThumperTalk, Inc. - All rights reserved.ThumperTalk is a registered trademark. The pilot jets were plugged.
When you buy through links on our site, we may earn an affiliate commission. Maybe its rich? It will no longer accept full throttle. I go to start it and it turns over 2 or 3 times slower than normal and then stops. Oops, sorry for the ambiguitybut more like the actual symptom itself. When the previous owner first started the bike for me it popped through the carb which I believed would be a lean condition due to a mucked up pilot circuit. made sure everythings cleaned well, when we start it we use fluid because Excellent video. I should add that I live in a hot climate 25-35 degrees centigrade and at 1400 metres i.e. Is this a pilot issure or high speed jet issue. Most likely an air screw. If you can do that by twisting the carb and do it through the port in the bottom of the float bowl, then you'll be fine. You can experiment with different fuel screw settings, however most likely it is all pilot by then. Thanks. https://www.youtube.com/watch?v=FDRg49vzdxk. spark plugs good colour not sooted up or white. Temp is 70 degrees here and the temp at 60 down the highway was about 170-180s and in town it would creep up to 200+ one thing I did notice is that I was able to slowly ease off the throttle without it bucking and kicking and it was much smoother at cruising speed in 6th gear at 60 giving like a 1/16th throttle. I understand that the pilot jets appear to be to large but when the previous owner had the exhaust fitted she also had a Dyna Jet kit fitted,, Would this not mean that the dyna jet pilot jets fitted would be correct for the new exhaust gas flow ( it appears that with the Dyna Jet kit you get new main jets and pilot air jets,, would it be this pilot air jet that needs to be reduced in size , there are two pilot air jets in the virago carbs, the Dyna Jet kit replaces the number two pilot air jet,,, or would it be the regular pilot jet that needs down sizing ) and weather or not it is,,, why do you think only the front pipe is popping/chuffing,, I`ve tuned loads of bikes over the years but have never had this problem. Install the 32 and report back. Since your best idle is at almost closed fuel screw position, I would decrease pilot by 1-2 sizes and see if you can get fuel screw in the 1-3 turns out range. Michael. Kinda scary the couple times it did that lol. Tackle, Bait. The Dellorto carb doesnt seem to use the same system as is described in the article as it has a metal Air mixture screw with a spring on it (I could link you a picture for a better idea, but Im not sure if your site allows it). I had taken a good look at them when I had the carb out the first time and they looked good. How else would fuel end up in the line tho? Hello, saber6 or anybody with knowledge of 82 honda atc 200, Hi, i have a 85 suzuki lt 250 lt, have cleaned the carb, and it starts fine, and idles fine, but when ,i have the gas wide open, it starts to break down,on not running right, i read your post,tryig to figure out if its running too rich or to lean, and what should i do, if you can help me thanks, you can find a shop oem manual here fairly cheap, and you can download it right after payment. For cabruretors size 44mm and larger, you will need an aftermarket billet thumb throttle to open the carburetor all the way. With the bike HOT and idling around 1100 RPM or so, turn each 1/4 turn in at a time until idle begins to stumble.
I have a 42 pilot and 165 main and the fuel screw is 5 turns out. Runs good. Cookie Policy - Runs terrible at those settings. I am not familiar with this engine; however, I am surprised at the high noise level at the inlet to the carburetor when the air cleaner and/or air box is removed and the throttle is opened full position. But when I left it right where it was. Supposedly he worked for Universal Studios fixing all kinds of machines anyway thank you for help. I decided to put in the 70 due the mods to both the air box and muffler. Content on grizzlycentral.com is generated by its users. Problem is, I dont know if the pilot jets in the carb are stock (manual says 17.5) or smaller/larger. Stock pilot jets were too rich. But this bog is what has me confused. I should also add that with the mixture at 4 turns out when I take it for a test ride the lower rpm and smaller throttle openings are smooth and extremely responsive (more then it ever has) but since the sync the mid has been kinda lack luster. It has an ignition advancer +2 and k&n filter. Im from South Africa.I got hold of a Sachs Madass 125 with 3000 ks on the clock.As far as I could see on the internet, these bikes are fitted with Mikuni carbs,whereas mine has a TK carb on (round/slide).Main jet=94,Pilot jet=40.Could you please tell me how many turns out, the air screw should be?Cant get it to idle propperly THANKS. You won't believe all the crud it'll keep out of your carburator and turning a fun filled day into a nightmare. The Fora platform includes forum software by XenForo, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada, yfzcentral.com is an independent Yamaha enthusiast website owned and operated by VerticalScope Inc. On deceleration with throttle closed? For example, with throttle blades closed, one passage will be on engine side, while the other on airbox side. Thanks. Sounds like youll have to take carb apart and record all jet #s and compare to stock and go from there. Remove air cleaner and tape all but the bottom 1/8-1/4 of carb inlet and see if conditions improve. The fuel screws should be responsive. Clip is in the 3rd position and put in the 132 jet. At that RPM and throttle position, you needle and mains are flowing, so those are the circuits you need to pay attention to. Next 1/4 turn idle down. In reading through your postings I saw how you helped Brent Pfeiffer with his carburetor issues and I was wondering I provided you with all the information on the issue Im dealing with along with the results of my trial and errors, if you felt up to analyzing the info to see if you might recognize a solution. On a carbed bike, they usually have it to monitor throttle position and possibly control ignition timing and maybe a fuel circuit. Would not getting enough air cause that? DO you have any idea what the problem is? Ill keep you updated. Hey Mathew, I have a 1998 Kawasaki 400 4 wheeler (actually 2 wheeler) I was not getting high end or fast acceleration so I rebuilt the entire engine including new carb. I put my mitivac on that line and left it all noght and it never budged. I have tried every gear and all different rpms and its no better no worse. If your slides flutter, make sure they are perfectly clean and operate smoothly. Will report how it went after I get them, maybe itll help anyone else. A pilot air screw will be located on the air box side, while a fuel screw will be located on the engine side. So I set both needles at 3-1/4 turns out and test drove the bike 10 miles or so. I tested the new tps and it tested good and way different then my old one. Would i need to start all over again with my pilot jetting? Now back on. Yes pilot jet is the slow jet, same thing. OK. 2. Secnodly, I have a problem. Until I synced then it was way more responsive. Havent taken it around the block yet because at this setting the bike idling in the garage needs the fan to stay at 225 degrees and that seems higher then I feel comfortable with.
However, if this is something new, check for exhaust & vacuum leaks, as they can cause this as well. If you go back to the link I provided on tuning cutaway, there is a graph from Mikuni that shows each size changes fuel flow by 10%.
It's called a "stone" fuel filter in that you'll see what looks like a golden stone inside the filter housing. Cool. The main jet is responsible for 3/4 to full throttle position running. After idle, number 4 plug is petrol wet when pulled. I have the same xs750 77 triple you have worked on.
Both carbs should be tuned to the same number of turns out on the pilot fuel or air screw. I almost always have to choke it to start it even after its warm. Should I put in new plugs? How many turns out for smoothest and highest peak RPM with the 17.5? Its way loud and if the mechanic tuned to proper specs, somethings off cause my old one never idled like that.
A rich condition will cause the engine to sputter, and emit black smoke from exhaust. Gonna order online so will take a week or so but Ill let you guys know when I get it put together. hi i have a yamaha grizzly 660 2004 what causes it to back fire when i let up on the throttle after driving at about 60 -80 km hr please and thankyou. Keep increasing until fuel screws net you 3 turns out for peak idle RPM. I reset mixture screws after the change it smoothest idle was atleast obtained. But the spark plug is minor lean. Any ideas or suggestions would be greatly appreciated.
Hi, I own a 1986 Yamaha fazer. Take carb apart and verify pilot jet is clean. For a better experience, please enable JavaScript in your browser before proceeding. If not, I dont know what else I can do. How it sounds below:-, http://vid1277.photobucket.com/albums/y493/jgl9/yammissfire_zps2db14cb6.mp4. Try the the 4 stroke needle jet and report back. The carbs are off of a XR600R using all the XL600R air box and exhaust. So next day it sits over night and i try no choke. A pilot air screw will be made of brass, gold in color, and will have a blunt tip compared to a pilot fuel screw. I mean absolutly perfect.until i started moving and temp dropped to 160-170 where it normally runs and boom stumbling and studdering like crazy so bad a fe2 times off the take off i thought it was gunna die out completely. Then repeat for the other cyl. and fuel screw 2.75 out. The ones for the 4-stroke appear to have larger side holes. Engine begins to sputter as you increase throttle position to full throttle. I know this should be a little hard to say, but how much of a change does one usually go with the cutaways, considering I have the 45 and the others being 40, 50 and 55? Based on your video, I would guess that the pilot screw is too rich. To lower the idle, the slide in carburetor need to move down. The motor starts but dies in a second. : removing and dismantling the engine for internal inspection (rings, valves, timing chain setting, valve tappet clearance setting, etc.) What do you think? So I experimented with a 20% difference. Any suggestions to eliminate the bogging? Runs awsome from little over 1/4 to 3/4. If it starts fine w/o choke then its too rich.
OK. We need to get together soon. should i go to a higher jet i think its got a 150 main stock. To confirm that this part fits your vehicle, please choose a vehicle from the "My Garage" list OR enter your vehicles details below. I went from 122 mains to 125 mains and the color on the plug is headed in the right direction, light tan to pinkish. You have been a huge help btw. Thanks a lot ,now I can work from there!! It sputters until i get to the higher RPMs. I believe they are 40 mm flat slides and from what I read online it has one fuel screw and one air screw I could send you a picture if you still have the same #.
Its fit while engine on idle. The previous owner tried to make an attempt to do the same thing, but failed miserably. Also my temp is around 70s right now and altitude is 1400s above sea level, Sounds good. Hello, I have a 2004 Yamaha Raptor 350 with a stock carb and stock everything. Tusk, GYTR? Well heres the update. All you did is changed the mains which is 3/4 to full throttle fueling. Plus end of pipe was turning light greyish white. It almost seems like a misfire in a car.
It is sold by a company called factory pro. my 1977 cb 750k7 backfires thru the number 2 an3 cly. Probably overkill for this engine. Awesome! Once I fully close it, the bike shuts off even when the engine is warm. Your video and additional information helped me to find my solution to this issue. Thx. Martin,there are so many ATV's out there, it's impossible to know if your model had a inline fuel filter on it when it came from the factory. Your a life saver. I have a Chinese copy of a Honda XL125. They do a good job of filtering down to probably 20 microns or a little more of crud. I know that the stock air cleaner is very restrictive. Electric tape, RTV, etc..never seem to hold up. Hi I have a 1966 Yamaha 250cc model YDS3 that I am restoring to running condition the needle and seats are bad and leaks fuel when not running do you know where I could get replacement needle and seat or a way to reconditioned the ones I have I am also looking for other items maybe you know someone that might have some parts or could help in my search, You should be able to order OEM parts: https://youtu.be/eqe59cINk7A, Your email address will not be published. grizzlycentral.com is not in any way affiliated with Yamaha Motor Company. I bet you will find that 1-2 sizes larger than stock is what the bike would want. Maybe its an electric valve that close main jet? Raise needles 1 clip position. Get back to me on what you have. You probably had a stuck float. Report back after test ride. Bought as a left over from a dealer this spring so its only had gas in it since June. The float levels are fine and I synced the carbs per your video. Since you can turn in all the way in and it will still run, I would recommend dropping pilot jet 3-4 sizes. So Im wondering if that would be opening that un-meatered hole and causing my stumble this whole time. A forum community dedicated to Yamaha YFZ owners and enthusiasts. I have not replaced the Air Cutoff Valve (ACV) yet. The hesitation, is it a bog (lean) or rich (sputter)? First time I did the top end and a screw backed out of the cam sprocket while driving falling into the crankcase and breaking the sprocket. When you remove the jet, it will be stamped with a number, indicating size. Hi Matthew, I have a 1980 Yamaha XS1100 Special with pods and aftermarket exhausts. The Fora platform includes forum software by XenForo, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada, grizzlycentral.com is an independent Yamaha enthusiast website owned and operated by VerticalScope Inc. So far I am impressed with handling and performance. So i was testing a few things here and there and find the throttle position s3nsors resistance tested way out of spec. The bike when it was sold in the us had a retarded timing to meet regulation. Honestly, I dont have much experience with TPSs. I mean enough to make it run perfect then like crap just like that. We have to determine if its too rich or lean. Almost like its lean on the main jets. As a first step Ill unscrew all 4 spark plugs and check the conditions. I have a Kawasaki zrx1200r with 36mm CVK carbs. Is the stall from a bog? Have you had these carbs apart? The jets came in tomorrow, but as it turned out, the 36 is still too big. It almost sounds like the tone of the exhaust has changed also.
To be honest is was a little better but still ran similarly. Every carburetor know to man will have a way to adjust the air fuel ratio at idle. Hey Matthew, finally got the jets. Thanks. As soon as the choke is on and want to start the bike , it wont start. Carb 3 main 128, pilot 42. Too much advance can cause bucking like you described. once it starts it idles for maybe 2-5 seconds and it dies, weve tried Usually, I would expect the clip to be one position lower than stock and the mains 1-2 sizes bigger than stock. I dont know what to do. The GYTR screws are $35 after all. But it was done at a way different altitude then where im at now. About 2 months ago I had the carbs cleaned due to a drop in fuel mileage, from 120 miles to about 85 miles.
I did exactly as u said and went a half turn out to compensate and now the only time it sputters is when trying to go like 5-10 mph which I would consider exceptable from where it was at. And when you say blip.is it a small blip? I am in Devon, UK and there is a lack of yamaha carb experts here! Trying a 1/4 turn more fuel tomorrow. Have you verified the pilot jet size in service manual? Carb 2 main 112, pilot 45. have proved by pulling plug lead on 4 and engine note still the same on idle. Once it is started, pry the cap/screw out, and you can access your mixture screw. Stock is 130 outer and 125 inner. My mixture is at 2 3/4 and if i go leaner it seems like the idle drops and isnt as smooth. It has a full yoshimura pipe k&n air filter and lid hot rods hot cams hi compression piston and possibly has been bored out also. The ATV's carburators work by "gravity feed" and ARE NOT under any pressure at all. https://howtomotorcyclerepair.com/how-to-tune-a-motorcycle-main-jet/. Id follow the carb mfg spec for float height and stick with that. My idle was below 1000 rpm when I made the fuel screw adjustment. So i held the throttle wide open and it turned and fired atleast. What did the instructions say to install? Im not noticing any change in oil level so im not thinking its hydrolocking from filling a cylinder with fuel.
People park their motorcycles outside, especially in the winter, with untreated bare metal interior, part-empty fuel tank causing the inside surface of the tank to rust. Why are you trying to lean it out so much? Straight in line 1600cc (97ci) with four (BCF) keihin carbs. Sounds like wah wah wah wah wah all the way down the street until I give it a little more gas. Thanks again. I cant gather whether you are rich or lean on pilot. JavaScript is disabled. No not really, just doesnt pick up quickly from first applying the throttle. What style carbs? I ended up at around 2.25-2.5 turns, engine runs smooth. What should I try? Privacy Statement - The other should be the air screw (assuming this is an air screw carb). Also, can you send me a link to the jet kit? The purpose of the images above is to illustrate the differences in the tip, which will indicates what the screw meters. The pod filters may or may not let more air in at idle. Are you going to move on to the needle and main? Hey I have a 99 Polaris sportsman 500.we bought it and we rebuilt the carburetor and now when we ride it after a while it doesn't have any power. raptorforum.com is not in any way affiliated with Yamaha Motor Company. What is your setup here? But if I got to full choke it idles better. If so, it might be a rich spot. new spark plug yes indeed. So i check my mixtures and they are at 2 1/4. I test drove it and it is still boggy/skippy when taking off from a stop. Thanks for the reply! Engine run idle on fuel screw 5 counterclockwise. I have to use the choke for cold start for 5 seconds and then everything works great. How to i adust the jet screw ,whether i want to turn clockwise or anti clockwise. I removed the spark arrestor from the stock exhaust and this caused my quad to backfire frequently. Do you feel like trading a beer for a diagnosis? a 87 LT250R QuadRacer, Im sure Ill have more questions for you since all of them are having The only issue Im still having is that the bike is quite prone to stalling when I add very little gas (as in from a standing start at a traffic light). The pilot is adjusted for max RPM and hopefully is in the 1-3 turns out range.
I know the bike is running rich for sure(throwing fuel out) and it has a off idle hesitation. So Im thinking that is a good sign. Sometimes bikes are very lean from the factory. I have dismantled and inspected the carburetor three times to check for other potential carburetor problems with jets and passages. The *fuelscrew* (not an airscrew) on the Keihin FCR-39 carb is at the engine-side of the floatbowl pointing straight down. Another test is to turn the choke partially on and then do another acceleration test. Problem is that on idle, runs OK, when i add more throtle its still ok. .but when i ride and had over 5K (5 and 6th gear) RPM, its almost dead. I have an update on the gsxr. Dynojet stage 1 kit, original airbox&filter, Mivv slipon muffler, new sparkplugs, pilot screw: 2,5 rounds. Also any modifications like exhaust or pods? Thank you for the information. Ive tried opening the pilot screws from 2 turns out to 4 turns out but still the stalling trying to rev off an idle. Not yet, just hoped that previous adjustments would work. I guess this bike just came mega lean from the get go but how didnt it hessitate when new?
I am currently tuning my carb and would greatly appreciate some guidance. Dont use any downward pressure since the screw may plunge down and the tip will break in body. For a better experience, please enable JavaScript in your browser before proceeding. The bike has aftermarket air pods and Vance and Hines exhaust. At WOT, vacuum is low, and you have a leak, so fuel delivery will suffer. I am not mechanically inclined and the mechanic that originally did the work in no longer in my area. Refresh your browser window to try again. When you buy through links on our site, we may earn an affiliate commission.Copyright ThumperTalk, Inc. - All rights reserved.ThumperTalk is a registered trademark. The pilot jets were plugged. When you buy through links on our site, we may earn an affiliate commission. Maybe its rich? It will no longer accept full throttle. I go to start it and it turns over 2 or 3 times slower than normal and then stops. Oops, sorry for the ambiguitybut more like the actual symptom itself. When the previous owner first started the bike for me it popped through the carb which I believed would be a lean condition due to a mucked up pilot circuit. made sure everythings cleaned well, when we start it we use fluid because Excellent video. I should add that I live in a hot climate 25-35 degrees centigrade and at 1400 metres i.e. Is this a pilot issure or high speed jet issue. Most likely an air screw. If you can do that by twisting the carb and do it through the port in the bottom of the float bowl, then you'll be fine. You can experiment with different fuel screw settings, however most likely it is all pilot by then. Thanks. https://www.youtube.com/watch?v=FDRg49vzdxk. spark plugs good colour not sooted up or white. Temp is 70 degrees here and the temp at 60 down the highway was about 170-180s and in town it would creep up to 200+ one thing I did notice is that I was able to slowly ease off the throttle without it bucking and kicking and it was much smoother at cruising speed in 6th gear at 60 giving like a 1/16th throttle. I understand that the pilot jets appear to be to large but when the previous owner had the exhaust fitted she also had a Dyna Jet kit fitted,, Would this not mean that the dyna jet pilot jets fitted would be correct for the new exhaust gas flow ( it appears that with the Dyna Jet kit you get new main jets and pilot air jets,, would it be this pilot air jet that needs to be reduced in size , there are two pilot air jets in the virago carbs, the Dyna Jet kit replaces the number two pilot air jet,,, or would it be the regular pilot jet that needs down sizing ) and weather or not it is,,, why do you think only the front pipe is popping/chuffing,, I`ve tuned loads of bikes over the years but have never had this problem. Install the 32 and report back. Since your best idle is at almost closed fuel screw position, I would decrease pilot by 1-2 sizes and see if you can get fuel screw in the 1-3 turns out range. Michael. Kinda scary the couple times it did that lol. Tackle, Bait. The Dellorto carb doesnt seem to use the same system as is described in the article as it has a metal Air mixture screw with a spring on it (I could link you a picture for a better idea, but Im not sure if your site allows it). I had taken a good look at them when I had the carb out the first time and they looked good. How else would fuel end up in the line tho? Hello, saber6 or anybody with knowledge of 82 honda atc 200, Hi, i have a 85 suzuki lt 250 lt, have cleaned the carb, and it starts fine, and idles fine, but when ,i have the gas wide open, it starts to break down,on not running right, i read your post,tryig to figure out if its running too rich or to lean, and what should i do, if you can help me thanks, you can find a shop oem manual here fairly cheap, and you can download it right after payment. For cabruretors size 44mm and larger, you will need an aftermarket billet thumb throttle to open the carburetor all the way. With the bike HOT and idling around 1100 RPM or so, turn each 1/4 turn in at a time until idle begins to stumble.
I have a 42 pilot and 165 main and the fuel screw is 5 turns out. Runs good. Cookie Policy - Runs terrible at those settings. I am not familiar with this engine; however, I am surprised at the high noise level at the inlet to the carburetor when the air cleaner and/or air box is removed and the throttle is opened full position. But when I left it right where it was. Supposedly he worked for Universal Studios fixing all kinds of machines anyway thank you for help. I decided to put in the 70 due the mods to both the air box and muffler. Content on grizzlycentral.com is generated by its users. Problem is, I dont know if the pilot jets in the carb are stock (manual says 17.5) or smaller/larger. Stock pilot jets were too rich. But this bog is what has me confused. I should also add that with the mixture at 4 turns out when I take it for a test ride the lower rpm and smaller throttle openings are smooth and extremely responsive (more then it ever has) but since the sync the mid has been kinda lack luster. It has an ignition advancer +2 and k&n filter. Im from South Africa.I got hold of a Sachs Madass 125 with 3000 ks on the clock.As far as I could see on the internet, these bikes are fitted with Mikuni carbs,whereas mine has a TK carb on (round/slide).Main jet=94,Pilot jet=40.Could you please tell me how many turns out, the air screw should be?Cant get it to idle propperly THANKS. You won't believe all the crud it'll keep out of your carburator and turning a fun filled day into a nightmare. The Fora platform includes forum software by XenForo, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada, yfzcentral.com is an independent Yamaha enthusiast website owned and operated by VerticalScope Inc. On deceleration with throttle closed? For example, with throttle blades closed, one passage will be on engine side, while the other on airbox side. Thanks. Sounds like youll have to take carb apart and record all jet #s and compare to stock and go from there. Remove air cleaner and tape all but the bottom 1/8-1/4 of carb inlet and see if conditions improve. The fuel screws should be responsive. Clip is in the 3rd position and put in the 132 jet. At that RPM and throttle position, you needle and mains are flowing, so those are the circuits you need to pay attention to. Next 1/4 turn idle down. In reading through your postings I saw how you helped Brent Pfeiffer with his carburetor issues and I was wondering I provided you with all the information on the issue Im dealing with along with the results of my trial and errors, if you felt up to analyzing the info to see if you might recognize a solution. On a carbed bike, they usually have it to monitor throttle position and possibly control ignition timing and maybe a fuel circuit. Would not getting enough air cause that? DO you have any idea what the problem is? Ill keep you updated. Hey Mathew, I have a 1998 Kawasaki 400 4 wheeler (actually 2 wheeler) I was not getting high end or fast acceleration so I rebuilt the entire engine including new carb. I put my mitivac on that line and left it all noght and it never budged. I have tried every gear and all different rpms and its no better no worse. If your slides flutter, make sure they are perfectly clean and operate smoothly. Will report how it went after I get them, maybe itll help anyone else. A pilot air screw will be located on the air box side, while a fuel screw will be located on the engine side. So I set both needles at 3-1/4 turns out and test drove the bike 10 miles or so. I tested the new tps and it tested good and way different then my old one. Would i need to start all over again with my pilot jetting? Now back on. Yes pilot jet is the slow jet, same thing. OK. 2. Secnodly, I have a problem. Until I synced then it was way more responsive. Havent taken it around the block yet because at this setting the bike idling in the garage needs the fan to stay at 225 degrees and that seems higher then I feel comfortable with.