Hi All,

We finally got our Ossa TR 350 out on the rough stuff at the excellent Eboracum 2 day Charity trial, My son Scott rode it on the Saturday only and for just two laps but we had a great time and the bike performed quite well and got lots of positive comments from the other riders / owners.

One problem pointed out to me was the bike was running 'Rich', at the risk of proving how un mechanical i am can anyone tell me how to adjust this, also I am mixing Oil to Petrol at 75cc to 5lts is this correct.

Cheers,

Vaughan & Scott.

If it was suggested it's running rich it could be too rich in oil or the carb could be letting too much fuel through - or both. Either would cause uneven running and excessive smoke.

Oil - 75cc is a bit lean on oil for an old steel liner engine, even on modern synthentic, so that rules out too rich in oil. I'd suggest 100cc per 5 litres though which is 50:1. Castrol TTS is good and doesn't gum up rings and silencers.

Carb - if standard jets are fitted, could be the float height set incorrectly letting too much fuel through.

It's something that is difficult to answer without seeing the bike running or knowing why people thought it was rich. Did they just mean it was lumpy off idle, in which case it is more likely to be just carb adjustment.

It could also be a gunged up silencer which can also give the same symptons as a bike running rich.

First check to do though is the carb, make sure jets are correct, none loose, needle position correct and float height correct. If so, then a restricted exhaust could be a possibility. What they used to do on those is cut the rear silencer open, rip out all the wire wool 'packing' and then drill a hole in the end so the exhaust gas goes straight out, rather than exit through the holes underneath. No idea if this is worthwhile mod or not as never tried a 'before and after' bike but I'm told by someone who's done it that it makes them go better. If the middle silencer is gunged up you can cut it open and re-pack it. It's is a pig of a job but worthwhile if it's needed.

Hi Woody, The Lad 'Owner of a Mint Honda' said it was running rich as "it was not picking up" as well as it should.

Im sure it is not the silenser as it was de bunged just recently, it could be the Bing carb cos i have been having probs with it leaking, i tried setting it up myself but it is looking likely that it may be the cause of my problem,

Thanks for the tip on fuel mix i will do that straight away.

Cheers,

Vaughan.

try winding the mixture screw out a full turn and see if that helps but it may need more or less its really a fine tuning job tbh but a turn out should be about right

Carb leaking could be caused by a dodgy float valve, which would also cause it to run rich.