dajogejr Posted March 27, 2008 Report Posted March 27, 2008 What happend in this case more than likely is the motor was worn out and had low compression. At that point, pump gas and 19cc domes weren't an issue. Once the motor was healthy and had good compression...with 19cc domes it was detonating. Plug locks do more harm than good...If a bike is detonating, you WANT the plug to back out. It's telling you something. Backing a plug out can save your motor...instead of smoking a piston by cracking part of the dome off or putting a hole in it. boonman...good to see you still around. However, with respect to my own experience...I disagree. I got too greedy on my drag bike, leaned out the power jet just a little too much, it leaned out...detonated, and broke off a small part of the crown above the intake side. Pictures sent to 3 respectable builders all said the same thing without reservation. It was 100% my fault. I fattened the Powerjet back up, ran the bike with two used pistons the rest of the season and didn't change anything else. Easily 100 to 150 passes on used pistons....no issues. Detonation is caused by excess heat or hot spots in the combustion chamber. Without enough fuel/oil in the chamber, it can cause...well, detonation. What was particularly odd was my piston broke at the intake side. That had me puzzled...normally, as you said...it'll melt the piston on the exhaust side, which is the hottest part of the piston. Quote
05Special Posted March 27, 2008 Author Report Posted March 27, 2008 now that you mentioned that, the burn on the domes looked uneven...it was black on one side and clean on the other. Quote
klemet banshee Posted March 31, 2008 Report Posted March 31, 2008 Do u still have that coll haed? Quote
05Special Posted March 31, 2008 Author Report Posted March 31, 2008 Yes I still have it... I put the single carb setup and and the stock head.. I suffered a MASSIVE loss of power..Now after driving it spits sometimes and shuts off... I'f I pull the choke it will keep running.. It is acting like the bowl is running dry but everything is fine.. Quote
dajogejr Posted March 31, 2008 Report Posted March 31, 2008 Is the intakes sealed up properly, and what jetting are you using? Pulling the choke to keep it running usually means it's WAY Lean. Quote
05Special Posted March 31, 2008 Author Report Posted March 31, 2008 the carb is a 35mm keihin, runnin 190 main, 55 pilot and 2nd clip from the top.. Quote
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