Hi there, Not long ago i got a new Sherco 125, i took the plug out the other day to see what it looked like and it was really black! So obv it needs more air, but i don't know which way you screw the air mixture screw to make it leaner? If anyone could tell me it would be great. The carb is the standard Dellorto.

I had a feeling that it is out?

Also because this is my first NEW bike i was just wondering whether you usually have to fiddle with them to get them right? for example the mixture screw. I have greased all the bearings etc.

Many Thanks!!

Edited July 12, 200917 yr by gasgas4life

Turning the air screw in gives it more air I think. Have you changed the gearbox oil? As that needs doing soon after you get a new bike. Looking at you profile thingy it says you have a shercoR does that mean it is a race 125? If so it would be interesting to see some pics! Good to see someone moving to sherco!

Yep... sherco race 125. its awesome!! had a gasser before and the sherco has loads more power, really good

Would post some pics but don't know how!?

You guys need to understand that a generic plug reading like this is not a good indicator. You would also be well advised to check with your local dealer to see if the the preferred jetting is installed, as most "out of box" bikes are off.

Once run in, the bikes perform well at 80:1 mix on the oil, too much can darken a plug.

But back to your basic question, on a Dellorto the screw controls the low speed fuel flow. NOT AIR, so turn it in to get less(lean mix), out to get more(rich mix). This mainly effects idle and less than 1/8 throttle. Usually around 2.5 to 3.5 turns out from fully in. Varies a bit with the day to achieve best running.

You can play with this and learn something. If the screw is IN too much(less fuel), the idle can get floaty and the bike may react poorly to throttle.

If it is out too much, the idle can be lumpy and poppy, one needs to seek the happy medium, probably about 1/8 turn at a time, once in range, and then adjust accordingly for the day. Adjustments done at normal operating temps(warm motor).

Thankfully, the 125's do not seem to be as sensitive to changes in temps and pressures as the larger bikes, so finding your "sweet spot" can be easier. But if you are having to run 3.5 turns out to get things to work, you might want to consider a larger pilot jet. Here, on our fuel, 34-38 range seems the norm, and i have found that a bike set too lean, say at 30-32, will cost you power and response. Your screw setting can be your guide on the jets.

Hope that helps,

Edited July 13, 200917 yr by copemech

Thanks alot! yes that helps... so for example in a 5 litre petrol can how much oil in 'ml' would you put in? Because we might have put too much oil in. It recommends 2%, so is this not right?

Thanks alot! yes that helps... so for example in a 5 litre petrol can how much oil in 'ml' would you put in? Because we might have put too much oil in. It recommends 2%, so is this not right?

That would be 62.5 ml per 5L, or 12.5 ml per L , high quality synthetic racing oil.

2% or 50:1 is just too much, not needed.

And eve at the 80:1 ratio, if you are putting about a lot, one needs to take the bike out for a run through the gears a few times to get some heat into the muff and blow out some accumulated oil in the exhaust. May smoke a bit(lot), this is good to keep things cleared out and rid of excess buildup in the muff.

Edited July 14, 200917 yr by copemech

That would be 62.5 ml per 5L, or 12.5 ml per L , high quality synthetic racing oil.

2% or 50:1 is just too much, not needed.

And eve at the 80:1 ratio, if you are putting about a lot, one needs to take the bike out for a run through the gears a few times to get some heat into the muff and blow out some accumulated oil in the exhaust. May smoke a bit(lot), this is good to keep things cleared out and rid of excess buildup in the muff.

Thanks for your help, much appreciated. We definatly put too much oil in!