I have not yet I just replaced my valves and am debating if I will need to rejet. Did you replace the float needle and seat? I am in Devon, UK and there is a lack of yamaha carb experts here! Should I just disregard the manual? Did you check the choke plungers to see that they seal? Hope you can help. But the spark plug is minor lean. I bought the kit from Amazon, its made in Taiwan and quality looks pretty good. Ok I will and Ill check back in when I do. I removed the spark arrestor from the stock exhaust and this caused my quad to backfire frequently. then used del. Your knowledge of the subject is very impressive and the best presentation that I have encountered at this point in my efforts to resolve a high RPM sputtering problem with an 05 Honda Ranger TRX350ES. No need to take that whole cover off, unless you are doing some major work. Sometimes this is considered normal with a race engine and open pipe. Also, Ive just heard from my parts seller, it appears that my carb is made for a 2-stroke but my Yamaha is a 4-stroke. But the problem isgetting it to rev off of an idle, it wants to stall. The *fuelscrew* (not an airscrew) on the Keihin FCR-39 carb is at the engine-side of the floatbowl pointing straight down. I am not so sure, have dismantled and cleaned again and cannot find any issues, no corrosion or blockages and looks identical to the others. I have 135 mains, and 45 pilots i believe. Most guys end up with a 45 or 48. thank you for the reply Matthew. 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. I did some adjustments on fuel screw while engine was running. Thanks. Ive cleaned the carb completely, increased main jet/modified needle jet per dynojet instructions. My manual says crazy numbers for the factory setting on these carbs. In your case, I would start with 2 sizes leaner. A forum community dedicated to Yamaha Raptor owners and enthusiasts. Is this a stock bike? 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 #. Any lower than 1 it starts to idle rough and stumble I went further to 3/4 and it was almost gunna stall. 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. Yes it does. Thanks for the answer! Every carburetor know to man will have a way to adjust the air fuel ratio at idle. And the tip of the pipe being white/grey was another lean indication i was thinking. I almost always have to choke it to start it even after its warm. Is that possible? So i went out and choked it and boom hydrolocked again. It ran good. So Im wondering if that would be opening that un-meatered hole and causing my stumble this whole time. I dont trust mechanics, I took it to one and he charged me 400 dollars and there was no change to it. If you on the throttle hard then let off itll have back compression and slow down but if you ease on the throttle till about halfway then let off it conitues to rev at that level for a few seconds and then gradually slows down and the rpms decrease. Well that did not go as smoothly as planned. I pulled off the vacuum line to the fuel valve and it was wet and had alittle bit of fuel in it. Thanks Matthew. How to fix it? Well it finally dies when I screw the mixture screw all the way in. Thats what is leading me to believe the needle setting may be where Im off. Thanks. I even fully tighten both screws but still idle does not drop. Check for vacuum leaks. I went from 122 mains to 125 mains and the color on the plug is headed in the right direction, light tan to pinkish.
I have an 82 Susuki GS650G, Canadian Model. These motorcycle filters are heavy plastic, but "glass clear" in appearance to let you know they're filtering properly with crud sticking onto the filter innards or you see things floating around in them, and cost is less than $5.00 and I would also recommend asking the motorcycle shop for some little "spring wire hose clamps". This video walks you through removing them. So i held the throttle open and it started just like before. You won't believe all the crud it'll keep out of your carburator and turning a fun filled day into a nightmare.
But if I got to full choke it idles better. Thanks again for everything. Kinda scary the couple times it did that lol. I have experienced the same with that model.
BTW, I find it odd that you have to go leaner on pilot, usually these bikes are lean from the factory. or maybe i need to setup the float more lean? You'll likely need to pull the carb to get this plug outif you aren't familiar with the carb. Try tuning the fuel screws at engine temp of 160-170. Its hard to tell if its a lean spot or a rich condition .Carbs are cvk30 keihin.Any suggestions Thanks .Phil. For a better experience, please enable JavaScript in your browser before proceeding. Trying to get my 2001 Sportster 1200XL to run, I cleaned the carb out and replaced all gaskets and o rings as well as new float pin(may be issue need to know whats correct setting of pin), I can crank the bike over with choke open once I release it kills out and fuel begins to overflow from carb. I bought the jets from Dennis Kirk.
List all mods and what your current temp and altitude are. Hey guys, got my parts from cheap cycle, took them a week and a half or so for them to get the parts to me, did the carb rebuild and replaced my diaphram, bike runs very strong now! Thanks. The parts seller gave me info on which the 4 stroke parts should be (the atomiser with its bush, if Im not mistaken, this is supposed to be the needle jet) although they arent sure whether the bike will run better with these 4-stroke parts. Still better then with the 15s but not fixed yet. Remove the needle/seat assembly and use a small screwdriver or pick to remove the tiny little filters and clean them. The carbs were highly conteminated because of that and the needle valve stucked and my garage got a very nice petrol smell for a few months. i have looked on various sites and they say there is only one size of pilot jet and there non adjustable due to some regulations? Im wondering if the whole time that has been leaking and what was making me need such massive pilot jets. Sorry Im pretty new with carburetor here. I have read a few carb books over the years and it was always confusing. I have completed all of the usual attempts to troubleshoot the problem; i.e. Not familiar with your model, but here is a 90 screwdriver made for those hard to reach fuel screws: I have a 1994 honda shadow vt1100c I am sitting at about 3.5 turn out. You will have to take apart carb and verify the number stamped on the jet and compare to stock. Probably overkill for this engine. Eventually Ill be upgrading to a k&n air filter eventually so I just want to get an idea of what my carb should be set at. On the road it is not noticeable. First off, thanks for the compliments, and the KLR is a cool bike BTW!
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. the top end revs seem good and there is power. 2-2.25 turns the engine starts to stumble. Runs terrible at those settings. It would be money well spent to get a Zip-Ty. i cleaned my carbs and i need to know how many turns out i need to set the air/fuel screw?any info will help thanks alot. Will it run with choke off? But wheni i pull throttle a little bit in idle to cca 2-4K RPMs, and release throttle, the RPMs are going slow to normal. Is this a new problem? A forum community dedicated to Yamaha powersport owners and enthusiasts. I replaced everything on the carbs including rebuilding the choke plunger pads. Where do you recommend getting good jets for these bikes? Why are you trying to lean it out so much? Like my articles and How-To videos? Thanks a lot for help (For the 100hp model 128 main and 42 pilot) This means that carb 4 is correctly jetted but not working. If everything mechanically is sound and no vacuum leaks, yes go ahead and buy 2 AND 3 sizes up from where you are at. Your help, opinions and views are greatly appreciated,, I would love to solve this issue. Get that sorted out and move on to the needle and main. Hey Brent, try shutting the fuel off and running the carbs dry before letting the bike sit overnight. Is that normal? I tried close the pilot screw all the way till it lightly sited and the engine still running. Found this place, the screw was cheaper, and the shipping was fast & free. If there is an internal leak, then it will cause problems. These require special fuel filters and special designed fuel lines. At that RPM and throttle position, you needle and mains are flowing, so those are the circuits you need to pay attention to. air fliter boks had some oil in clean that out, i also forgot when brakeing als back fires, Hi, Try to to lean the screw its not helping. I have a 97 gsxr 750 sport bike that has 4 CV carbs. Acceleration above idle to redline-ish is fine. Dont try to eliminate this by increasing pilot jet size. Both of these should not have any cracks otherwise it will introduce air leaks (vacuum leaks). I currently have a needle valve #300 and a float with the weight of 9.5 grams and the fuel goes almost to the top of the needle jet. Seems to be running very rich. Actually, this 360 ran pig rich with stock pilot jets at 17.5. Ill be sure to do that this weekend, what do you mean by Read the plugs? Thanks in Advance Ive adjusted the needle hight to several positions but I cant seem to iron out that boggy spot! Have you adjusted the fuel screw after removing the spark arrestor? It wants more fuel. Per the advice of my local Honda Dealer, I installed 122 & 188 main jets. 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. 2003 Polaris xc700 2 stroke. (on other cylinders, engine nearly stalls) Stock thermostat is 180 correct? I found some good info regarding jetting on. I have a short video of my ATV condition. I am currently tuning my carb and would greatly appreciate some guidance. I am eager to hear what you think. Sounds like it wants more fuel. Would that be the thing to try. Installed the 4 stroke needle jet size 268 (smallest one available). Understand carbs better but am still lost. I got it working really well afterwards, a lot of power, but I heard a clicking sound after about 2 months and I thought maybe it was something I did in the carbs. When I attempted to adjust the pilot (fuel side) screws backing it out made little difference in RPM. And when you say blip.is it a small blip? (https://www.youtube.com/watch?v=5AqqQ6jnR5I). Next time you have them apart it would be best to bump pilot jets up one size. Thanks for the reply! I was thinking my pilot was to lean but now I dont know! Lets define the carburetor butterfly or slide the dividing line between the air box side, and the engine side. Currently is hard starting and pops through the carburetors while trying to start it. Your screw is a fuel screw since it is engine side and pointy tip. Give the bike what it wants and dont get too tied up in the difference from stock. I tried close the pilot screw all the way till it lightly sited and the engine still running. All you did is changed the mains which is 3/4 to full throttle fueling. Straight in line 1600cc (97ci) with four (BCF) keihin carbs. So far I am impressed with handling and performance. Iam I going in the right direction? Ill keep updating until i get it. Thanks a lot ,now I can work from there!! 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. Let me know how I can help $ you to help me and this machine! Im gonna try another 1/4 turn in. And will pulling the baffles help to correct the problem by leaning the mixture out a bit and allowing me to turn a/f screws in without having popping. Another test is to turn the choke partially on and then do another acceleration test. Ill keep you updated. If it will only run on starting fluid, then the carb is not delivering fuel. Ive got mods and the carb was professionally jetted. Both carbs should be tuned to the same number of turns out on the pilot fuel or air screw. Hope you can help. Is that an accurate way to see if a leak in the boot is whats causing my problem? Ill keep you updated. What I still cant wrap my head around is why do I need so much more fuel at idle and my mains are only 1 step up. Hello I have a 2005 yfz450 , air intake uni and a gytr pige on it I have the pilot jet 45 and am out 4 turns , I change it to a 48 and and it dose go to 2 turns but the rpm dont come back down quick when I let go of the throttle???
Its odd that you get 2 turns out with 17.5, and 5 turns out with 15. I have worked on a few carbs myself with good results.
Adjusted floats the max both ways.Oh 115 main jet. My airbox does have holes drilled into the back of it though. They do let more air in at higher RPMs. You can replace the jets in the carb without completely removing the it. It is from a Suzuki GS1100L 1983. A forum community dedicated to Yamaha Grizzly owners and enthusiasts. On deceleration with throttle closed? Awesome! Are you going to move on to the needle and main? Bike runs amazing if Im flogging it.
To confirm that this part fits your vehicle, please choose a vehicle from the "My Garage" list OR enter your vehicles details below. 3 weeks ago I finally have enough time for the carb cleaning and applying the new stuff in it. 2022 Lectron Fuel Systems. Oh and I have the next size up and its 17.5 should I go 2 steps and get the 20? This bike drives me insane. Ill keep you posted. Id follow the carb mfg spec for float height and stick with that. Hello Matthew, The rebuild kits I bought include jets and the pilot jets were the same on the orifice side but the air holes in the tube side were smaller. Recommend one over the other? Before if I tried to idle lower it would surge the whole time.
How many turns out for smoothest and highest peak RPM with the 17.5? The tip of my pipe Is turning brownish tan instead of black the way its been since I got the bike. The bike has an annoying problem. So I rebuild to carbs and had the carb bodies professionally boiled out. its strange. When you close the throttle and decelerate, the engine runs lean, and can pop through the exhaust. Sweet, Thanks man. Great idle and throttle at the bottom end but getting top end sputter. 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. Ive had my fuel mixture screws turned out about 2 -2.5 turns, but it would bog everytime I throttle it (eventually it dies). It also does this while riding. There probably is some way to adjust the fuel mixture via a pilot air or fuel screw. Is in under the bowl cover or??? Is it possible for my main or needle to be lean and cause my mixture to have to be way rich to compensate? I have the same xs750 77 triple you have worked on. So everything is fine except 1 little thing: fuel consumption. The bike has a full Yoshi exhaust header and silencer. Thanks. You need to address the other circuits of the carb. Ive read your link and I think it makes sense, especially seeing as it almost always gets flooded when going from half to 3/4 gas even though the needle is in the lowest position and the main jet is the right size (no problems at full gas, high revs). Thank you! My float hight is factory which is 7mm from the gasket surface with the float just touching but not compressing the needle spring. Do you have to take off the 17mm bolt or bowl to get to the air screw? Find a different shop! But i changed them with new ones and it still didnt completely fix it. Im thinking the carbs had never been synced and my adjustments were on it before it was synced properly. Engine begins to sputter as you increase throttle position to full throttle. This bike will be the death of me. When I take off from idle it pops just off idle every now and again. Most likely an air screw. If so, how many turns out for max idle RPM and smoothness. the popping is finally gone (about 3 turns out on pilot screw). I have a 2008 Yamaha XT125 with a 150 ccm big bore kit and an Arrow exhaust and Ive recently fitted a Stage 6 R/T Dellorto VHST 28 caruburettor on the bike. 
