1990 xt 350 problems
Posted July 15, 2010 - 07:12 AM
Posted July 15, 2010 - 11:07 AM
have you verified you have a good battery? good stator? all connections nice and firm?
how do you KNOW you have good compresion? did you test it with a compression tester?
if the spark plug is black and fouled looking, its not firing right and must be replaced.
Posted July 16, 2010 - 04:25 AM
Don't worry about the battery. It doesn't have to have a charge. Mine's been dead for 20 years.
Posted July 16, 2010 - 05:31 PM
Posted July 19, 2010 - 07:39 AM
Posted July 20, 2010 - 04:04 AM
Posted July 21, 2010 - 08:28 AM
Posted July 21, 2010 - 08:51 PM
Posted July 22, 2010 - 03:21 AM
Posted July 22, 2010 - 09:49 AM
Cam chain skipped a tooth. Bent valves, trashed the piston, possibly bent the rod. Shame you did not tend to the bikes problems before you tried to run it hard.
Send the head to WilliamsMotoWerx ot Engine Dynamics, see if it can be salvaged. You'll need to incpect the rod for true.
Posted August 11, 2010 - 07:23 PM
Posted August 12, 2010 - 04:22 AM
i found a head for an 84 xt350 would that fit my 1990 xt 350?
They didn't make an XT350 in 84. '85 was the first year.
If it is a xt350 head and they just got the year wrong, it will fit. 1985-2000 heads are all the same.
Don't buy it unless it comes with the cams and caps. After they break in, they become a matched set.
The 1984 XT250 head looks like the 350 head, but I don't know if there are were any changes.
Posted August 13, 2010 - 04:53 PM
If you try and reuse your head, can't have any small metal projections into the combustion chamber or you will beat the engine to death from detonation. (pinging: caused by sliver of aluminum head glowing and acting like a spark plug)
Whatever head you use, get new valve seals installed, and be sure to have the valves cleaned up and relapped. Can't grind these, once through the hard coating, they wear instantly, have to buy new. But a bit of 400 grit Clover compound and a light relap will do wonders. With the head upside down, and a spark plug installed, you should be able to fill the combustion chamber with gas (outside please) and not see any liquid in the ports after five minutes. If so, it's valve job time. Worth every penny if you want to really use the bike. That stupid cam chain tensioner got you (sadly) good. Check both of the cam chain tensioner rubber arms for wear and replace if suspect. Sudco sell a lot of stuff like that. I just told another post here about some other XT 350 stuff, go read it so I don't need to repeat.