New Member, Tri Moto identification help?

[gcavy1]

Hello,
Just acquired a Yamaha Tri Moto that we are going to use for building MTB trails.

Can someone point me in the direction on how to identify which engine I have? I found a stamping on the engine block, but none of the numbers match my searches. (last number is 78, I was thinking that was the year, but looks like they didn't start making them til 79'-80') Also found some numbers on the head.

As I understand it there is a 125cc 2 stroke, 175 2 stroke, and 200 4-stroke. Pretty sure its a 2 stroke. It does have a front suspension fork, looks like the 125cc models were rigid?
I can't find any other identification numbers on it.

It definitely matches the pictures of the early 80's original versions

[350for350]

The two stroke engines look similar to a Yamaha Blaster engine. Except that they haver a pull start instead of kick start. They also have an auto clutch instead of a manual clutch. As far as I know you're right about the 125s being rigid while the 175s had front suspension. If it is a 175, that may not be the best machine for building trails. They are known for being wheelie monsters so that may not be the best for slow going and blazing new trails. Then again, it may work just fine for you.

[gcavy1]

The two stroke engines look similar to a Yamaha Blaster engine. Except that they haver a pull start instead of kick start. They also have an auto clutch instead of a manual clutch. As far as I know you're right about the 125s being rigid while the 175s had front suspension. If it is a 175, that may not be the best machine for building trails. They are known for being wheelie monsters so that may not be the best for slow going and blazing new trails. Then again, it may work just fine for you.

Haha yes, when looking for a three wheeler and asking around, most people said "aren't those things illegal!?" We're on pretty mellow terrain, but wanted the wider compaction you get from 3 sets of tread vs a 4 wheeler's 2. We were thinking we'd want racks to maybe add weight. Would like one on the front to help with that.

if it helps, the stamping on the engine is: 5V7-0006 78


Is it easy/common to change out the front or rear sprockets to lower the gearing? (so we could pull a drag with some weight on it)

[350for350]

I don't know much about the Yamahas. The front sprocket will probably be a lot easier to change than the rear. Without knowing for sure, I'm guessing that you'll have to pull the axle to change the rear sprocket. According to a thread on here called "Yamaha serial/VIN numbers" by Monroe Mike, it's a 1982 YTM175J. And of course you know now that these aren't illegal.

[gcavy1]

Oh I didn't know about that thread, thanks so much!

[350for350]

I had forgotten about it. Google reminded me. You're welcome.