<div class="FTQUOTE"><begin quote>Originally posted by: ds650 bomb

well it ran good but then the intake valves got out of tolerance so i put new valves in and while it was down i had the intake ported and polished and ever since i put it back together it overheats. It runs great up to the point it overheats (which is about 20 min.) then it misses and bogs down. I tore it back down to the cylinder today to see if i missed something, and nothing looks out of the ordinary. I don't know what could be?</end quote></div>

Did you rejet after having this work done. I would think that this would be causing you to run lean. being able to pull more air because of ported intake

 

sounds like lean jetting to me as well, fatten up the idle circuit and work your way up from there.

 

well indeed it was a bad head gasket it was missing a tiny piece of the gasket. so i think the overheating problem is fixed. but now i have a new problem, the magneto nut and washer came off while testing to see if the overheating problem was fixed and sheared off the woodruff key, and my have messed up the crank. If it was not for bad luck i would have no luck at all.

 

WOW, bad luck is right, that sucks, check the garage thread here and also freebay for eng parts, people are always upgrading or parting out.

 

<div class="FTQUOTE"><begin quote>Originally posted by: TheStir

<div class="FTQUOTE"><begin quote>Originally posted by: Cardiac



Stop by a smog station amd have them put a sniffer over the open radiator and see if you are getting exhaust in the system. The Rotax's are known to have a few head gasket problems.</end quote></div>



I have not heard of any head gasket problems with the stock bore, please elaborate.</end quote></div>

From a conversation I had and a couple of bad gaskets I ended up with there was a bad crop of them that went out. I will only get head gaskets from Eric now as he gets only the best ones. And I have not yet had a failure with those...

 

I run an oem bomb factory head gasket, plain with no sealant or magic tricks, with 14:1 compression, for going on 2 years, reving to 9.5K frequently.

 

You are luckier then me man....... I had two of those go out in a row......

 

wow that is bad luck. i never thought a bad head gasket would cause such problems