I am about to go through my 84 atc 200x engine. I can get a stock piston, a 10.5 to 1, or a 12 to 1. I am thinking about the 10.5 but the engine has NO compression release. Have any of you guys had experience with any of theses pistons and what is your opinon? Thank you!

 

bump, Planning on ordering next week and would like some "die hard" opinions

 

I would go with the 10.5:1 mostly because you would have to run the 12 on race fuel to keep from melting the piston.
BTW I run a 10.5:1 piston in my atc200s and I start it with a crank rope with no compression release [img]i/expressions/face-icon-small-wink.gif[/img]

 

Thank you. I have had a hard time getting any experienced opinions on this!

 

I've got a 12:1 in mine and compression really isn't a problem for kicking it over but you definately have to run racing fuel with the 12:1. The 10.5:1 you only have to run Premium Gas. If $3.50 plus a gallon doesn't bother you go with the 12:1.

Just my opinion[img]i/expressions/face-icon-small-happy.gif[/img]

 

I should add that with ANY higher compression piston you should get a camshaft and a bigger carb to fuel the fire and a aftermarket exhaust to let it breathe.

More than opinion this time its a fact.[img]i/expressions/face-icon-small-happy.gif[/img]

 

does the hich compession bother you get the rocker cover off of an xl185 it has a decompression release lever and it bolts right on!!! u just need to get a small cable to liek a bicycle lever on the handle bars to help start it there's my die hard input i did this with my 83 200x with a 12;1 piston then i sold it and bought a motor for my 86200xand got a tc rac motor that was stroked and bored and highly modified.

 

I would go with the 10.5 to 1, because you would most likely
have to run racing fuel with the 12 to 1piston. which can get expensive.
My 200x is bored .020 over and has 10.5 to 1 compression, and is bnot difficult
to kick over.




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85 200x

 

Update!!!!! I went through my engine and found some good news........it has a .020 weisco 10.5 to 1 piston and the head is fully ported!!!![img]i/expressions/face-icon-small-smile.gif[/img] it was all in great shape except the moreon that went through it before kept the original timing chain, guide, and tensioner (they were shot!). I will post some pics soon. I painted the frame, engine, swingarm, and exaust. This 84 is lookin' good![img]i/expressions/face-icon-small-smile.gif[/img]