| Author | Message | ||
     Piechey |
Firstly, I would like to apologize if this has already been covered. Last week I picked up my very first Buell. As soon as I got the bike back to the shop, I pulled the carb and and completely cleaned and pieced it back together. The bike fires right up and will idle all day. The moment you give it the slightest throttle, it dies out and backfires from the carb. There is literally fuel just dumping from where the needle sits in the bowl. I have printed the Keihin manual that I found here on the forums and I am almost certain everything is together as it should be. I have checked and the float appears to be moving freely. I am by no means an expert but I would definitely consider myself technically inclined. Any information that anyone could offer would be greatly appreciated. | ||
| Missionbolts |
The only needle I know of inside a Blast carb, which sit inside the bowl, would be the float needle valve. Perhaps you mean the needle on the main jet? I'm assuming it's something you are directly observing while the engine is running. If so, then that would be a case of the float bowl flooding from a failed float valve. The tip of these valves can look fine by eye and still fail in actual use. I've had plenty of situations where an old float valve would seal ok before starting the engine, but fail due to the vibration of the running engine When you look at the tip of one of these needle valves, if you can see any sign of where the valves is sealing against the seat, such as a band either indented or just a different shade of black - the valve is shot and needs to be replaced | ||
| Piechey |
Wow, Mission. Thank you very much for your prompt reply. The needle that I am referring too, which I have described quite poorly,is the jet needle. I am observing this while the engine is running, correct. You can see fuel spitting up the passage of the jet needle from the bowl. The float valve, it the small object the can only be removed after the float itself has been, correct? Meaning directly under the float pin and retaining clip? | ||
| Missionbolts |
Ok, just as I had thought. Your carb is probably just fine as it is, with the only issue being that the float valve is not working anymore. You need to get a new float valve. Part #27886-78A https://www.ebay.com/itm/Keihin-Replacement-Float- Needle-Valve-22732-OE-PART-27886-78-27886-78A-/173 617005286 | ||
| Piechey |
Mission, I received a full CV rebuild kit yesterday. I rebuilt the carb, slowly, following the manual found on this forum. Great news, I cannot start the bike easily now. I say this is good because I am no longer spilling fuel from the carb. Seems you were likely correct. I have to spend some time this afternoon, when work slows a bit, to start playing with tuning. In the short amount of time I had to fool with bike last night, I was able to start it about 3 times. Only once did it idles for any more than 5 seconds. It is still running rich as of now, however, as I said, I am not seeing fuel spill from the "main jet hole" for lack of better terminology. | ||
| Missionbolts |
Ok, sounds like the beginning of getting some good progress! I'm a bit concerned that you might not have done the carb rebuild thoroughly enough? There's a lot of very finicky cleaning of passages, jets & other parts. It sounds like I might have been wrong about the carb being ok other than the float valve If everything is absolutely spotless inside, all jet orifices, mixing tube holes & secondary fuel outlet holes downstream of the main throttle slide are free of anything that might cause turbulence or restrictions, then there's still the adjusting of the auto-enrichener that should be checked Also known as a 'automatic choke'. If that's why the bike is running too rich, then you should try screwing in further https://www.youtube.com/watch?v=toYTwg2XR-0 I have the factory service manual for the 2005 Blast, ought to be mostly the same for all other years. This PDF has a fully built-out index, so finding relevant sections is a lot easier than just doing a word search. 426 pages, bit under 13 megs file size. Hosted on my own account here: https://mega.nz/file/7U4RzLYY#WBqf5E1qpHiqVEEa5XFV Of-m9GaD5tFQVlHMgaCGeiY There's a complete chapter on the carb, plus full wiring diagrams and everything Best if you save that to your own computer before any HD lawyers notice! | ||
| Piechey |
Mission, you gave me the insight needed. I do believe that you were partially correct about the float needle being the cause. I say partially because I found that I had put the collar that sits atop the emulsion tube in backwards also. Cannot say which truly solved the concern, however after having gone through this, I would probably recommend purchasing the full CV rebuild kit if anyone had any concern in the carb. I think I paid $20 for the parts shipped to my door. I will also say that this truly is a simple carb that one can easily find in depth YouTube videos on. Thanks again for the help Mission; and thank you for posting the '05 Manual! | ||
| Missionbolts |
Cool! |
