Hi Guys,

Just a quick question is it normal for a 2 stroke engine to click when it hits compression its a new engine and i havent run it yet but it makes a small click every turn when it hits compression ???????

I have mostly Os engines and they dont but i was told by someone at the field once his Irvine engine did that and was fine...........

I had the same thing with my old OS FP 40 when it was new and I was worried, but bit the bullet and started it up, and no problem!
Probably it is the piston just tightening up on the tapered bore at TDC when it's new, ( and when the cylinder is cold).
My OS always was (and is ) a sweet running and easy to start motor!

Normal, check here for more-

http://www.mecoa.com/faq/abc/abc.htm

Yep, normal, and Willdo has the cause nailed, at least in part.

The tighter the bind at TDC when new, the more power you're likely to get out of an ABC engine. Not always true, but my experience has always been that the tighter the engine, the more RPM I get out of it later on.

You know, you shouldn't be cranking over a new engine by hand. Because of the nature of the ABC engines, by forcibly cranking the engine over, you may be ruining the engine. Maybe I'm being overdramatic but cranking it over while the engine is cold is a sure way to lower compression. For the same reason, you should never run the ABC engine rich enough that it is four-stroking. This doesn't allow it to get to operating temperature and... you got it, ultimately lowers compression.

WHile technically true, I don't think turnaing a new ABC engine over by hand a few times when it's cold will do much damage. A very rich running engine will be turning over at least 5000 rpm, or something like 90 rpm per second. It would take a LOT of turning over by hand to do much.

I agree with the others about the clicking. I've seen it on a couple of engines at the club field, guys always being concerned about it. Has never been an issue in the end though.
Dennis-