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Posted by Stephan Rose on April 13, 2008, 11:10 pm
On Sat, 12 Apr 2008 10:49:42 -0700, Rick Cortese wrote:
> Eat Dirt wrote:
>
>>
> <snip>
>> folk know your bikes). One detail though: it backfires. For instance,
>> if I'm in second gear doing some 45 km/h (30 of them US measurement)
>> and let go the throttle, I get a nasty backfire, followed by several
>> smaller ones. Also happens while idling, if hitting some high revs and
>> letting go of the throttle. What can be done to rectify this? I know
>> I'm very close but not sure how to fine tune the thing. What could be
>> done next?
>
> Italian father<the Cortese part> Irish/German mother. This is my mother
> speaking "If it ain't broke, don't fix it!"
>
> Not specific to your bike but backfires were common to the point that
> Keihin developed a special carb that IIRC had a vacumm diaphram that
> would dump fuel into the engine on throttle rolloff to prevent backfire.
> I suspect you may still be a little lean but I don't know that I would
> tamper with it.
>
> If it were me I would check timing before touching the carbs again. Just
> accept the fact that you may have done it right with the carbs, at least
> for now.
>
> There is a really odd relationship between timing and gas/air mixture
> that I don't think is well described anywhere. It goes something like
> richer works with more retarded, advanced works with leaner. There's
> also, to me at least, the counter intuitive: More retarded =>
> overheating.
>
> Anyway, since the bike is a quarter century old there is no telling what
> happened since the last ice age. Someone may have tried to set the
> timing by seat of the pants. It is something you have to double check
> *before* fine tuning the carbs anyway. You could waste a week fiddling
> with the carbs only to reset the timing by 5 degrees and have to start
> with the carbs all over.
Man, the more I read this thread, the more I appreciate fuel injection!
--
Stephan
1986 Pontiac Fiero GT
君の事思い出す日なんてないのは
君の事忘れたときがないから
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