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ATCGuy
11-14-2003, 08:59 AM
HI! I think I have a problem with my 85 ATC. I just rebuilt the top end on my trike because the piston and rings got fried. when I rebuilt it I thought that it was sand that had gotten into the cylinder because the air tube fell of the air box and was sucking air without the filter. I ran the bike for a while and now the same problem has happened without the air tube falling off. Both times the piston was gouged on the exauhst side of the piston. I'm beginning to think that the exauhst bridge on the cylinder is causing my problem but I'm not too sure. Any Ideas as to what I should check/do?:confused:
250rAL
11-14-2003, 03:44 PM
Sounds like it's running lean. The exhaust bridge area is the hottest part of the cylinder so that's the area where the piston melts first.
Red Rider
11-14-2003, 05:57 PM
ATCguy, has your cylinder been bored out? If the cylinder is several times over on the bore, the sleeve may be so thin that the exhaust bridge bulges into the cylinder when it gets hot, which is gouging your piston. You may need to have the bridge area of the sleeve relieved a bit.
bones200x
11-14-2003, 06:05 PM
HAVE YOU CLEANED THE AIR FILTER? WHAT ALL WAS DONE? JUST RINGS?
Mr. Richard
11-14-2003, 06:23 PM
did your piston have exhaust bridge cooling holes drilled in it???
wiseco recomends drilling three holes down the skirt of the piston ,to cool the exhaust bridge,,,,, did you do any plug checks at all? do you have any idea how your jetting is? sounds lean or you have alot of detonation,,,,,, there are really to many factors to solve this problem here without alot more history too,,,,,
ATCGuy
11-15-2003, 07:17 AM
The cylinder is bored .060 over. I replaced the piston, bearing, and rings. The piston already had two holes drilled on the piston for the exauhst bridge. I run about 28:1 for a mix but I don't know about the jetting. I've never messed with it and just thought that if its running then its alright. The air cleaner was washed and the air tube was blown out so I don't think that it was foriegn matter in the cylinder. If the exauhst bridge has to be relieved does that mean that the cylinder will have to be bored more?
Red Rider
11-15-2003, 11:49 AM
No, it would not need to be bored again just to relieve the exhaust port. This is only 1 of many possible culprits for your problem. The list that Kasey provided above, could very well be causing your problem also. I know you're looking for a definite answer to your troubles, unfortunately that's very difficult to do. Good luck.