Won't start? Check for compression loss.

SomeOldGuy

New Member
When I got the kit, I was appalled by the low quality trash that passed for hardware and connectors. I was even more appalled by the the lack of any solid specs and info on these things.But I got it together and running and it ran for a little while and quit. I went through all the standard drills - fuel flow, carb, spark, etc.,etc.,etc. Everything checked out but I still couldn't get it to start.
To make a long story interminable, it turned out that the entire upper end was losing compression. What I figured happened was those cheap cylinder studs streched.
First, throw away those idiotic acorn nuts as soon as possible. Second, use a good gasket sealer on the head gasket ( I had a tube of Hondabond-worked OK). Third, seal up the intake manifold gasket.
Then get a good combination wrench and torque down the head nuts AND spark plug--probably somewhere around 20-25 ft.lbs should do it,but that's just my best guess. One online manual stated that the head nuts should be torqued down to 4-6 ft.lbs--I'm not making that up!
I did all that and the bike fired up right away.
 
look around a bit & you'll see about 12lb for 8mm head bolts & about 8lb for 6mm heads

I would only use metal based sealant on head gaskets so as not to interfere with heat transfer
 
Thanks for the numbers, I'll see how they work out. As for sealant on the head gasket; should any sealant be used at all? The head gasket is squishy soft aluminium and probably should be ok without any.
As a nondirect comparison; Harley Davidson K Model motors (flatheads) have an aluminum head bolted to a cast iron cylinder without a gasket. The factory called for aluminium paint (unspecified composition) coating the mating surfaces. It works well, but then again, entirely different compressions, RPM ranges, and it's a 4 stroke. I might try that.
 
I only use some aluminum metal paint when I've got to stack two head gaskets - for a single gasket, I don't use anything.
 
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