Thinking outside the box, or in this case, the barrel

Does anybody think it’s possible for a running but flooding engine to wash the cylinder walls down enough to lose enough compression to quit?

On 2 separate occasions under full load my engine has lost power and quit. When I tried to restart it felt like the sparkplug was out, there’s no difference between the decomp lever in or out?

After sitting and kicking occasionally for ½ to 1 hour, the compression gradually comes back and the engine fires. It runs terrible for about 5 minutes, backfiring and gotta keep it revving high to stay running. Then it clears up and is perfectly normal. The second time it happened I noticed that snow packed near the crankcase vent tube was black like there had been lots of blow by. The snow is there 6 months of the year and has never been black like this before. After removing the black snow and restarting, the new snow stayed clean after hours of hard riding.

I recently installed a 430 kit so the rings probably aren’t fully seated yet. Would a dry cylinder lose that much compression and allow that much blow by?

Are you using the 185 main that came with the kit?

Are you using the 185 main that came with the kit?

I'll have to check my notes but I think I installed a 200ish. I need richer for the cold, E pipe and Hotcams so I went bigger. I haven't dialed the jetting in yet.

I don't know about this happening while riding, but I have heard of it on a bike that sits for extremely long periods of time. So I would say it is possible, but probably highly unlikely. Hope this helps.



Do you think the decompression lever could be sticking open. Maybe check the cables. I'm not to clear on how the linkage is to open that valve, but that maybe why you notice no compression while kicking regardless of wether or not the lever is in, and why you are getting blow-by out the breather tube while running...just trying to get outside the box/barrel...good luck. Does that Hot Cam have the auto compression release? Is it warming up at all for you?



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