Fuel-oil mixture ratio ? 81 IT175

So I picked up a nice completely factory stock 1981 Yamaha IT175, I havent owned a 2-stroke in 30 years . What would be a proper fuel oil mixture for this vintage bike ? 32:1 ?



Yes 32:1 should work fine using a good quality modern two stroke oil. I would imagine that the bike's owners manual said something more like 20:1. However, the oils have improved a lot since 1981 so they lubricate a lot better than the old stuff.

By the way that bike is way too clean. It's a dirt bike. Get some dirt on it!

Thanks, It will get dirty soon.....joined AHRMA, going to try some post vintage cross country .


If that's a recent photo, you got a nice bike. :lol:

Yes, Yamaha recommended their Yamalube R at a 20:1 ratio.

The formulation of Yamalube R was different back then.

The bike would probably be fine with a modern oil (like today's Yamalube R) at a more common 32:1, though you might have to do a minor rejet of the carb.

I used to own the same model, although the one I bought (around 1990) was a classic basket case and made a nice project.

I fixed it up to good condition and even did the Yamaha Wrench Report modifications that came out for the 1980 IT-175G (same model in blue and white color, basically).

The mods were aimed at adding low end power and torque while keeping the top end the same or stronger.

I bet that these bulletins (actual paper publications) can still be found at a Yamaha dealer that was around back then.

Yes...I took that photo in the fall, I found it on Craigslist for $400.00. It was actually titled and on the road in the 80's in New York state and showed minimal wear. It had sat a long time and the fuel system was goop, straightened that out (new carb,lines and filter) along with a clean up,rear tire ,decals and a few other odds and ends.

I have it insured through the same company that does my antique cars . I am going to plate it as historical so I can zip down the road if the mood hits. Also planning on doing a couple of AHRMA post vintage cross country runs with it.

Thanks for the tip, I will look for the upgrade spec sheets .

really nice bike, im hoping my 79 yz will look kinda like that when i get white plastics for it.

OH MY GOSH! Wow, you have a really nice bike. I use a 32:1 mix in all of my vintage bikes, and I haven't ever had a bit of trouble from any one of them. if you want to play it safe, stick to 20:1. Better safe than sorry...

I run my 1976 MR250 at the recommended 20-1 even with the new oils.

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