Pinking at high speed with barely open throttle

[ArmandTanzarian]

I've just got back from a 50 mile ride which was a mix of lanes and motorway driving.

On the motorway there was a long, down hill stretch of a mile or two and so the scoot was doing around 65-70 in traffic with the throttle barely open at all. At that speed the engine had a tendency to pink and when I pulled in the clutch and closed the throttle the engine ran-on in that scary "I'm about to blow up" way that strikes fear into your wallet.

Would a bigger pilot jet help or does the needle want adjusting?

To make matters more complicated, in normal town and A road driving, the scoot is a bit rich at lower revs and stutters.

[firekdp]

Going down long, steep hill stretches at speed with the throttle barely open will result in the motor overheating, as there will be little cooling fuel and therefore not enough lubrication from the two stroke oil to cope with the piston speed.

[ArmandTanzarian]

Going down long, steep hill stretches at speed with the throttle barely open will result in the motor overheating, as there will be little cooling fuel and therefore not enough lubrication from the two stroke oil to cope with the piston speed.

I appreciate that but if the traffic is doing that speed then it's quite hard to do much about it.

[Diablo]

What carb are you running?
This can often be a problem on tuned Lammys and personally I'd rather run back and forth on the throttle a little rather than sit with the throttle part open at those speeds. For the reasons firedkp has just said. Sometimes you have to compromise things when you ride a tuned scoot.
You may find if you try and jet this out you find it rich when accelerating under load but its worth having a look. Mikunis are the hardest to sort with this problem in my opinion.

[firekdp]

I appreciate that but if the traffic is doing that speed then it's quite hard to do much about it.

If it's a long hill, then I would declutch and rev it every now and then.

[ArmandTanzarian]

What carb are you running?................ Mikunis are the hardest to sort with this problem in my opinion.

It would seem that that opinion is correct

[ArmandTanzarian]

This is proving to be a right pain in the parts.

Because it was running far too rich mid-range I lowered the needle a notch and tried to counter the pinking at very small throttle openings by increasing the pilot jet.

Mid-range it's now lovely and pulls strong and smooth from nothing to flat-out but if I back off the throttle at speed it's like a tin of ball bearings being shaken.


Oh, and it doesn't tick over as well as it used to either. ARSE!

Help!

[minotaur]

i had a similar problem once and found out the inlet manifold gasket was letting in a little air, it was never noticable on a short town run, but after opening up same probs as you

[Diablo]

Have you tired making adjustments to the air screw?

[J1MS]

A longer inlet manifold might help a little, thats if its possible to fit one?