cold plugs

its running 178psi across the board using the kawasaki method of testing, and it wasnt the plugs causing it to miss when warm, just too much gas and not enough ignition.

can u explain in more detail ? what were the symptoms ? u said your plugs were red hot ? i'm confused, but would like to here about your problem and cure for learning sake.

if you dont run cold enough plugs after the engine is warmed up acceleration raises the temps in the combustion chambers to the point where the tip of the plug glows red hot a preignites the fuel mixture.

soulution: drill the jets out and run e-85 ethanol, i'v yet to have the bike run this good without missing since the rebuild.

themachine wrote:

... 178psi on a 1400 mile 1170cc rated at 10.25:1

i had speed glazing on the stock plugs, its a yellowish tint with no resedue on the tips.
under acceleration when hot it misses, gets worse with lower octane and the hotter plugs.

Had overlooked the earlier psi info. Am thinking 178psi is too high, even with 10.25:1 (but could be mistaken), and not caused by carbon build-up after only 1400 miles.

With so much compression and heat, it's remarkable there's no sign of pre-ignition such as "pinging" or metallic residue on plug tips.

But it's understandable that higher octane fuel and colder plugs would help offset the compression and heat problems.

Might it be possible that the head was too severly shaved when modifying the engine? Maybe a second cylinder base gasket would sufficiently reduce the compression ratio.

Hope am reading correctly that the overheating issue has since been resolved.

Post edited by: Patton, at: 2007/09/08 14:12

i did'nt have the head shaved when i rebuilt it, but it was laser straight even with 34k on the odometer, i picked it up with 32k.

the machine shop said the bores were all odd sizes, like someone honed the crap out of it, it still had stock pistons