Need help diagnosing problem

sinister_customs · Posted: July 29, 2009, 10:05 pm Post subject: Need help diagnosing problem

Looking for some ideas on what may be happening with my bike, got it built back together about a month or so ago, road it for about 40 miles noticing it is running a bit lean with the new intake velocity stack set up i havebut not to bad. took off from my house later on in the day and it was backfiring and popping like an S.O.B! almost seems to not have good ignition system. Sometime it runs well down low but pops and backfires soon as i give it some gas. Almost as if the ignition system was not advancing properly? With this in mind i installed another ignitor box figuring that is what controlls that, that didn't work, although i need to keep in mind that the ignitor i installed was used and sitting in my shed for a few years. after i put the first 40miles on it i checked the pluges, one plug was white and the other was loaded with carbon, that has me thinking that on the carbon side it was not getting good spark. but is this possible? seeing that there is only 1 coil for both. i also checked spark with an inline bulb tester and it looked fine, compression is good, valves are propperly adjusted and jetting has been changed to xsjohns recomendations, i put his needles in last year and my bike has never run better, well til this year when i put it back together. As for work i did to the bike over the last year, i re routed the wiring into an oil tank off a harley wich also houses the battery. i installed a new seat, painted the motor, frame and swingarm. any ideas i will apreciate all thoughts. thanks
Jon

schtipp · Posted: July 29, 2009, 10:49 pm Post subject: Re: Need help diagnosing problem

maybe start that bad boy at night and see if your getting any arcing off the wire to the case, ( spark leaking out early). count the turns out on the mix needles. vibes might have moved it. replace the plugs. these are just my thoughts , use them at your good discretion. if you have a timing light, take a minute to rule that out. any trouble idling?some ignition troubles will be waaayyyyy worse at idle.

sinister_customs · Posted: July 30, 2009, 10:17 pm Post subject: Re: Need help diagnosing problem

off and on sometimes it idles smoothe although i found one cylinder is far hotter than the other, almost as if that cylinder is dead. it has fuel getting in, good compression and when i test spark its there, it makes no sense to me?

schtipp · Posted: July 30, 2009, 11:06 pm Post subject: Re: Need help diagnosing problem

tough nut to crack. sounds to me like your one side is way to rich at idle. compare the mix screws settings to each other, see if they're close to the same. you said one plug was really black, is that the one from the F-ed up side. if you have never checked float hight , i would check that also. have you had the carbs apart? are they jetted the same? and were the little black plugs for the pilot circuit seated good? take the plug cap off of the good side, put a spare plug in it and ground it to the motor. then try to start the bike on just the bad side. if it starts cold with no choke, put the choke on, if the choke kills it. it's probably too rich. if you ramp up the throttle slowly can you hear that side kick in and smooth out? if yes, then think pilot circuit needs attention.

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