Newbie Question (blown hole through piston)

[dunerider13]

I don't have a pic sorry, though I do remember that it was melted. I mentioned that to a friend as we were pulling it apart saying that it looked like it got to hot and melted a hole through it.

Thank You gpracer for that explanation.

Now another noob question. What carb is this? I have a manual for the 83 atc and it looks nothing like the one I have. This is prob where the problem lied and it wasn't tuned properly.

After talking to the guy I bought it from, he only had the thing for a couple months and rode it once and only for a few minutes.

Thanks for the help here, I've got the cylinder, head, and exhaust back together now and I just need to figure out what carb this is so I can get a rebuild kit and start riding again.

[SYKO]

that is a large mikuni like 38 or 44 what is your main jet size? if its 360 its a 38 if its a 540 its a 44 and WAY to big for a non big bore motor.

[dunerider13]

printed on the main jet is 420RD. I'm assuming it's a 420 jet. Correct me if i'm wrong. And I measured the smaller bore on the carb and it measures 38mm. So i'm assuming its the 38mm one.

[SYKO]

ok then its a 38 but jetted all wrong, that carb is way to big for that air cooled motor unless you have a 300 kit on it, I have a 38 on my 85 and it feals great except a low end stumble I have in it

[dunerider13]

what do you suggest I go with then on the jet size? Do remember that this is a ported cylinder.

[SYKO]

well Im not sure what you need to run on a air fooler, hopefully some more mikuni fans will jump in and help