YT125 needs a little help in the power department. BTW Iam a newb

[Fatboypc]

How's it going? I have lurked these hall ways for years now lots of info on here. Well finally decided it was time to join. I have a new project on the bench and I need some help. I just picked up a 85 tri moto 125. I am looking to gain some power I have been all over the search engine on here and there is lots and lots of info on the 125 and 175. But it seems like the more I read to more I got lost on what I needed to do or buy and some of the stuff is hard to find on ebay. So I thought I would ask for a couple of ideas to make more power. BTW this motor is going in a blaster for my niece (I know it as 4 wheels) She not ready for a clutch, But she is to tall for her moto125 plus its 4 stroke. So I was on CL lurking around when I found the yt125 and I thought why not.

Just need some basic ideas or decent mods. I know the exhaust is a big issue I will be making a blaster pipe fit. Looking for any ideas and info Thanks

[YTZ drew]

Welcome aboard! The YT125 should respond to the same mods that will wake up any 2-stroke: pipe, larger carb, porting, and headwork. I would probably get it fitted up and running in the new chassis, jet it for the new pipe, and go from there. You may find that it has enough power for the task at hand just the way it is.

[Fatboypc]

I am thinking you might be right on that YTZ drew. I think I am going to just take it and a little port work done fresh rebuild get the pipe built. What carb should I be looking for?

[YTZ drew]

When I look to upsize a carb on anything, I look at what bikes similar to what I trying to build are running. The closest thing I can think of to what you're trying to build is a Yamaha IT125. It ran a 30mm mikuni round slide, with the following jets:
main: 200
needle jet: P4
Pilot: 35
needle: 6DP19
That would probably be a good starting point, and you can tune from there.

[Fatboypc]

Thanks Drew. I was also wondering if the IT125 top end would fit the yt bottom end? I would think the IT125 would have better porting on it stock than the YT125. There is a jug, head, carb, carb boot and reed cage all on ebay.

[Fatboypc]

Never Mind that idea. The exhaust would be a pain to make to fit the IT jug.