LCGB Forums

I'm running a SX150 with a fairly standard 175 upgrade, which has been good since a new piston and BGM stator.

Went out yeserday and engine started fine, ran well apart from low revs, which was bogging a little. Adjusted carb to richer on the Jetex, adidn't entirely stop the problem but seemed to have fixed the tickover a little faster.

Today I had the carb opened and checked the choke was working properly, jets all clean, no crap in in the fuel chamber. Drove 4 miles to get some petrol, and the low rev problem was still there, so gave it a little more rich. Got it well enough it seemed to ride home, started up and engine quickly revved up to very high revs with no touch on the throttle... wouldn't turn off the engine with the key, turned off fuel.

I eventually drove home, same low revs, medium and high running perfectly, but at tickover same thing happened, out of gear quickly went up to high revs and couldn't be turned off other than by turning off fuel.

I've been riding Lammies since 1965, and this is problem a new one to me - anyone got a solution?

Sounds like an air leak ? The throttles should not jam on those slides as the spring is strong.

Thanks St George - I'll have a good look round the periphery of the carb for untight connections, check air filter. Any other places is should be checking?

Sorted! Spent an hour going more carefully through the checks I'd made before, but included retightening any thing that needed it. Checked pilot jet in particular, and a minute bit of something may have been dislodged when I used a nylon bristle from a dishwasher mop in all the tiny holes. Thanks again for advice !

Buy some carb cleaner for next time.Glad it's ok and well done.