Kick Starter (500 cc)
I think when I had a bike with a pet**** the prime position was needed to get fuel into the carbs when they did not contain enough fuel to start the engine. I think to make the pet**** open the engine needed to create vacuum which would open the pet**** valve so if your carbs did not have enough fuel to get the engine to run you wouldn't be able to get vacuum and therefore the engine wouldn't start, kind of a catch 22. The prime position by passed this feature but you could potentially drain the tank through the carbs over a period of time if you stored the bike with the pet**** left in the prime position. I suppose if there is a vacuum leak it could result in the engine not continuing to run.
P.S. the forum censor seems kind of touchy when it comes to fuel flow valves.
I appreciate the critique about not chasing ignitor box problem needlessly, but electrics are still part of the equation, and carburetion can also be a blind chase. That is why I suggested checking for a healthy spark (ignitor and subsequent connections), with a further look at whether the other electrics [lights, signals etc] were working when the bike quits, which would point to J-box.
It has happened to me and I blamed the carbs needlessly when it was in fact electrical. Just an observation and easy to analyze, I certainly don't advise running out and buying anything unless it's needed. There still remains the need to isolate the cause of failure, which I still think needs to be addressed.
I suggest pulling spark plug immediately when the bike quits (wearing gloves of course, the b*gger will be hot). Is the plug wet or dry? black, tan or white? Attach lead, ground plug on head (use caution, need block of wood etc to avoid shock) and then hit starter> is there a good blue/white spark? If all is well, great. Next avenue is fuel flow and fuel mixture.
Simple basic stuff to isolate the cause of trouble.
Last edited by Smiley; 03-06-2012 at 04:40 PM.
Beginner (125 cc)
Well, after following all of the very good advice in this thread (and from some other resources), I've finally fixed the problem: specifically, I sold the bike to someone who wanted to mess with it more than I did LOL
Over the last while, I went through the entire electrical system testing and cleaning connections. I drained the carb and pulled the bottom of the bowl and used some carb cleaner and mild doses of compressed air to see if that loosened up any gunk inside it. A few other odds/ends of troubleshooting. Bottom line is that the bike was still dying within a couple minutes of starting.
My plan was to ride this bike this year (as my beginner bike), then when Spring comes, sell it and up-size a bit. However, if I had continued to work on this thing, I would have gone beyond what I would have been able to sell it for, so I decided to just cut my losses while they were minimal (mostly my time, which I don't mind since I learned a lot).
The moral of the story is: a 3-minute test ride isn't enough to know you're making a good purchase. I now have a MUCH better idea of what to look for when buying a used bike, and next time will work out differently.
Speed Shifter (750 cc)
Too bad. I was hoping to read about your finding a solution to the problem.