Yamaha Tri Moto YT125 / 175 help needed

[newc14]

Hi all,

I recently picked up a 1985 Tri Moto 125 and a 198(2?) 175. The 175 is in pretty rough shape so it's going to be a parts bike, with the 125 being my primary build. My local area has MX races and there's a 125cc open class. I'd love to race a full suspension YT125. I'll use this thread to document the process (pictures coming soon) but also to ask for help.

The big thing is rear suspension. I know the resident expert with these things is (was?) Vealmonkey, but he doesn't appear to have posted since 2016. Does ANYONE have any leads or suggestions on where to find the pro-tec rear suspension kit? Even a partial kit is fine, I just need the swing arm and the upper mount, I can fab the rest. Alternately, does anyone have information about alternative ways to do this job? I've heard of people using and modifying the larger Tri-Moto swing arm, but details are sparse.

I'm also looking for aftermarket exhaust. I know the 175 is different from the 125, which makes it even harder. Supposedly DG and Bassani made headers for the 125 but finding even a picture of one is....challenging. Any help with either of these would be greatly appreciated.

Another question is a matter of opinion: to keep the oil injection system, or pre mix? I know a lot of people eliminate it to prevent failure, but how likely is this? The pump isn't very complex so I don't see many opportunities for failure, but I want to hear from people with more experience

[350for350]

Just throwing this out there. Maybe you could modify a Blaster swing arm to work?

[newc14]

I had that same thought and that's probably my best option. There's a lot of them available so I'm thinking I might even just be able to put the whole Blaster back end on, carrier, axle, and all. That would make maintenance/replacement parts easy in the future. If that's the direction I go I'll definitely document everything so someone else could do the same thing

[TrikeKid]

Yamaha's oil injection is a really solid system, I've seen a ton of folks delete it, never been able to find a verifiable case of it actually failing and damaging an engine without either being run out of oil or losing the cable to the oil pump. In a full suspension build I'd delete it but only to get the oil tank out of the way.

If you could get a whole rear frame section from a blaster I think that would be ideal for adding rear suspension, Pro-Tec kits are unobtanium at this point and any add on kit like that will be full of compromise to work around the existing chassis. It would at least give you some proven geometry to work with and adapt.

[El Camexican]

Sadly Vealmonkey passed away a few years back. He certainly would have been the one to point you in the right direction on your project.

I can’t add much other that to say the only rear suspension kits I’ve ever heard of was for the 175. Not sure if the used the same frame.

It’s going to be “challenging” to find the parts you’re looking for, good luck.

[shortline10]

Sadly Vealmonkey passed away a few years back.

Wow never herd that he passed away , I knew he had diabetes and his vision was bad .
Very sad news .

[El Camexican]

Wow never herd that he passed away , I knew he had diabetes and his vision was bad .
Very sad news .

I believe it wasn’t long after the fire. He was one of the good ones.