Hi

I have a 2005 Rev3 125.   It has all the symptoms of running lean, difficult to start, fast idle, hunting, and poor pick up on the throttle. (It has run fine previously.)

I have cleaned the carb to within an inch of its life including an ultrasonic clean, replaced the crank seals, the air filter, the plug, the hose between the carb and the air box, and checked the gaskets and inlet rubber, all to little effect.

It does seem to be marginally worse when the engine is hot.

Any thoughts on what else I could try?

What carb?

repack the exhaust when they get burned out it  knocks jetting all over the place

Hi, thanks for the replies.

It is running a Dellorto VHST26.

I have repacked the exhaust rear section and cleaned out the mid section,

can floats be in upside down ? or over flow/ breather holes blocked ? or a worn slide/carb/ o-rings  ---is 12yr old

If not the carb, I would check the main bearings.

I would spray some brake cleaner or WD40 all around the inlet manifold area and see if the engine note changes. If it does you have an air leak.

Edited August 18, 20179 yr by nzralphy

Hi

Thanks for all your suggestions.

I have tried the WD 40 spay but nothing.

Eventually I bought a new, bigger, pilot jet.  Went from a S42 to S44.

I don't think the mixture was lean but hoped that a bigger jet might be less prone to blocking.

Recleaned the carb, fitted the new jet and have just managed to get round a trial with no issues.

Not sure if there is/was something kicking around inside the card or if I was getting a new blockage each ride.

Airbox looked clean inside after the trial and I have already cleaned out the tank, the tap filter and fitted a new in-line filter so difficult to see that it was getting freshly dirty each time out.

Will continue to clean carb airbox and filter after each ride and just hope it continues to run OK.

Interestingly, even though I adjusted the mixture screw to take account of the bigger jet I did feel I had a bit more zip than before when picking up from low revs, but this might just be wishful thinking.

Stuart

On 8/18/2017 at 5:20 AM, nzralphy said:

I would spray some brake cleaner or WD40 all around the inlet manifold area and see if the engine note changes. If it does you have an air leak.

I don't think WD40 will work anymore. I think they stopped using propane as a propellant. Starting fluid will work.

On 22/08/2017 at 1:18 AM, dan williams said:

I don't think WD40 will work anymore. I think they stopped using propane as a propellant. Starting fluid will work.

Good to know, thanks