I'm hearing what I think is some strange ticking (slap?) in my IT175 motor ('81). I know there is a lot of experience here so I'd love to hear some thoughts. Bottom end and top end fresh rebuild (2nd over bore/piston), maybe 2 hours on it so far, most of that time was sorting our a 'rich' condition. I ended up dropping the pilot down 2 sizes (#60 to #50) and leaving the other settings stock. Runs pretty clean now with air screw about 1 3/4 out. Overall it runs well, but the ticking noise is bothering me. Comments are welcome!



Edit: A few more details on motor (post rebuild)...

-Compression 140 PSI
-Running 25:1 premix with Maxima Super M
-Pressure/vacuum test held 6psi/6inHg for several hours, needle didn't budge

Great audio thanks & sounds piston clearance. Was it a Wiseco as they run quite wide clearances. Whatever piston it was --was it finished to the correct clearance. Bike looks 'very' nice but i've never seen a white one, well, not where i am.

Thanks for the feedback, it's an OEM Yammy piston. So it sounds a bit 'slappy' to you? All i can tell you on the clearance is...I'm not sure (how's that for an answer?!) I sent the jug and new piston out to a shop who knows what he's doing. He did say that it was one of the worst out of round bores he's seen, and he has a few decades of experience. Unfortunately he was in a bad accident and has since retired, so I don't want to bother him with this.

1981 was a one year only in white for the IT. Not sure if it was N. America only.

It has an authentic early 175cc sound to it

Sounds 100% like an MX 2 stroke Yamaha engine from that era.

Audio can make it sound worse than it is, but only way to be sure if its worrying you a lot is pull it down & measure it or simply slide i feeler blade in with the piston gives a pretty good indication. If its only meant to run 2 thou & you can get 5 thou in then you've found the problem Next thing is--do ya run with it until its ready to bore again "like i would". Or go & bore it now.

Here's by free TF125 which rattles bad but goes good, which might make you feel better lol.

Here's by free TF125 which rattles bad but goes good, which might make you feel better lol.

computers going mad & can't edit my posts & now trying to delete second same post but won't work. Coming up with gobbledy gook at the top of the page, lines of something not making sense--or is it my computer only!!. reply only & quick reply work & that's all. Gave computer a huck out but didn't help.

I’m seeing the same thing, Rt.