TE/TC 100:1

I agree, marginal at best. If you do the math its a fraction of what a change in the weather/air density altitude would do.

No we weren't.

This is ancient history but when Belray MC-1 came out in 1979 the recommended mix ratio on the bottle was 85:1. I ran a whole season of MX at 85:1 on an aircooled 400 maico. Ran like a champ, no issue and 53 races on the same top end. I did need a piston at the end on the season, but the oil worked superbly. The new bottles say 50:1. I asked Belray about this and they told me that is was for public perception and most people were scared of running lean oil ratios. I now run the MC-1 at a sedate 60:1, but my old KX500 got 400 hrs summer single tracking and winter ice racing. Lots of great oils out there to use. I just wish the MC1 smelled like the Maxima 927. I tried the H1-R but somehow the bike didnt seem to run as well and gave more spooge. I think the main thing is to find a good oil that you like and stick with it. I am testing amsoil marine in my outboard this year. Cam.

You can get away with lean mix ratios with big bikes like that because you don't scream them like 125's. I did the same thing in the 70's with Belray and went through bottom ends on my 100's and 125's

Nice! I got Maico support in '81 &'82. I was in Boise and the bikes came from a shop in Kali. A leftover '78, then a leftover '79, MC250s. Both came with a case of MC1 and a Mik carb. We did break in at 32:1 and raced at 50:1. Don't remember what it said on the bottle