Hi guys,

After soom advise on what fuel mixture to run in my TR77 350, been a long time in coming but final got out on my bike this weekend after 30 years in boxes.

i'm running it at 40:1 mixture and leaving clouds of blue smoke in my wake.

Thanks Rick

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What brand/type of oil?

40:1 isn't too far off, i would never go below 50:1 on an air cooled bike of that era. Even at 40:1 your bike shouldn't smoke that bad, unless its an inappropriate oil or something up with your bike (seals or clogged exhaust). Ive run fantics and bultos as high as 35:1 and they didn't smoke excessively

Edited September 7, 20205 yr by faussy

My old MAR, was 35:1 on mineral oil.  If your using synthetic, 50:1 but nothing less!

hope this helps.

Hi Guys,

I'm using castrol power 1 racing 2t so should not be an issue, OK so i'm in the ball park the engine has been rebuilt so can discount seals, maybe a bit of old oil in exhaust.

It just seems a bit more smokey than i remember.

Thanks for the info.

Cheers Rick

If you have just rebuilt the engine I assume you used oil to lube everything on assembly, this has to be burnt off together with the new oil you are putting in with your fuel. How long did you run it for, probably take a good thrashing to sort it out ! ( no not really on a new engine )

Im guessing the castrol is fully synthetic. It may be too good, more for a racing or mx bike, 50:1 would probably be adequate. Most trials 2t oils are semi synthetic.

Edited September 7, 20205 yr by faussy

15 hours ago, faussy said:

What brand/type of oil?

40:1 isn't too far off, i would never go below 50:1 on an air cooled bike of that era. Even at 40:1 your bike shouldn't smoke that bad, unless its an inappropriate oil or something up with your bike (seals or clogged exhaust). Ive run fantics and bultos as high as 35:1 and they didn't smoke excessively

Same here, I run my air cooled bikes at 40:1 without any problems or smoke.

I Also used Castrol without any issues at 40:1

Could be a damaged seal, or wrong way round?

Edited September 8, 20205 yr by suzuki250

Run the engine and carefully lay the bike over onto its side and rev the engine a couple of times. Bring the bike back upright and lay it over on the opposite side and repeat. Bring back to upright and mow rev the engine and see if it still smokes, this action usually clears the crankcase of any excess oil from the build up or standing for a while. Has the exhaust been cleaned out at all?

I use Castrol 1 Racing Fully Synthetic @  75/1 in my Beta evo and it will smoke when you have to give it some especially after periods of low revs type sections 

I think this oil is almost to good for low revving engines  

Years of oil build up in exhaust

Only way to get it out take pipe off blow torch it out

Do it in sections. keep at it till flames stop coming out

One small thing to consider, In your fuel air mix, oil isn't fuel but takes up space in the fuel stream. If you make a change in mix ratio, you have also made a small change in fuel air mix.