Engine won't rev..... help!

[Hughieboy]

Evening All,

I've just stripped and rebuilt the top end and added a 30mm phbh Dellorto and TSR EVO exhaust. I've matched the exterior porting to the new manifolds. Scooter is a Harry Barlow/Suzuki 190 conversion. Carb came from Cam Lam with ball park jetting. All was good and it went well straight off the bat, plug colour looked fine etc...

The other night, all of a sudden it started to die, I eased off the throttle and it remained running at low revs but died whenever I tried to open it up. Since then I have stripped the carb to check for blockages and the jets are clear. The rubber mount is fine and not split. I have replaced the ignition switch as this needed doing anyway. Fuel is flowing (new Cam Lam fast flow tap), petrol cap vent is not blocked.

Still it does the same, it's ok for about 200 yards then starts dying again. I have changed the plug. The plug cap is new as is the lead. Choke is not sticking. I did a leak down test when I assembled it. I'm at a loss to know what to look for next, has anyone got any ideas?

Spoke to Cam Lam and they said the jetting may not be spot on but it should be near enough as they've sent it jetted the same as they do for their Imola kits.

It's almos like fuel isnt get through but it must be, take the foam filter off and there's plenty spitting back out but it just won't rev.

I'd be really grateful if anyone could shed any light on what to try next, supposed to be going to a rally for the day tomorrow and I've run out of ideas!

Thanks in advance....

[rosscla]

Try it with the fuel cap off, if it's any better the breather is blocked.

Also check for an air lock in the fuel pipe.

[mick1]

stator or cdi ? worth a swap to eliminate if nothing else.

[olliewtf]

sounds more like stator breaking down to me.... particularly if fuel side has been checked in a reasonable manner.

[wack 63]

Very often the pick up causes this

[Hughieboy]

Ok, so there does seem to be an air bubble in the fuel pipe that builds but it doesn't seem to affect flow, ie undo the pipe from the carb end and it flows freely..... I've double checked and double cleaned the carb and jets completely..... How do I check if it's the stator or pick up breaking down? I don't have a spare to put on. Is there a way of working it out? Starting to think it's not fuel either, it did happen suddenly....

[Chris in Margate]

Forget the air bubble; that's a "red herring".
You need to borrow a spare stator or CDI off a friendly fellow scooterist and swap them out. Failing that you'll have to buy them and try. They can always serve as spares.

[Hughieboy]

Forget the air bubble; that's a "red herring".
You need to borrow a spare stator or CDI off a friendly fellow scooterist and swap them out. Failing that you'll have to buy them and try. They can always serve as spares.

I did wonder about the air bubble..... I wouldn't know it was the if I didn't have a clear pipe. Is there anyway of checking the cdi or stator to see which is faulty before replacing?

[Chris in Margate]

CDI...No

Stator. There are resistance readings you can take with a meter to check continuity and insulation resistance of the coils. Sorry I am at the golf club at the mo and dont have the readings to hand but hang on a while and somebody will be along in a short while.

[rosscla]

White - Earth <0.1 ohms
White - Red - 95 - 120 ohms
White - Green - 450 - 540 ohms

This assumes it's wired with the red from the pickup and the green from the LT coil with the white as the earth.