C90Club.co.uk

Hi I have recently bought a C50ZZ. I am having trouble getting it to run correctly in that it idles irratically and when it is under load like going up hill it will start to misfire and bog down. When I go back down the hill it seems to run a little better but still no power. It runs slightly better with the choke out. I have replaced the points and timed the ignition (opening on F and 0.3mm gap at top dead centre), new condenser and spark plug. The valve clearances are set to 2 thou. I have cleaned the carb all of the jets and it has a plastic float tab so assume height is correct. I have set up the air and mixture screws but it still won't run correctly. The needle clip is set to 2 down from the top, it won't idle at all if set in the middle position. I would like to rebuild the carb but can't seem to find a kit for the ZZ. Would anyone know where to buy one from or if a kit fyom a Z2 would be ok. It has a #78 main jet as specified but the Z2 is specified either #68 or #70. Any help would be much appreciated.

Simon.

check plug and ht lead and cap?

http://www.allensperformance.co.uk/shop/

Thanks for that I will give them a ring. I have replaced the plug cap and spark plug with new items, but it won't be the first time I have had a faulty plug right out of the box! I will check the ht lead as well, could it be the ht coil?

Simon.

don't know about the coil

I wonder if you're cam timing is out, maybe skipped a tooth?

you will have to wait for the clever folks to pop along...

The coil is very robust but made of unobtanium.....

The condenser however would be my first suspect.

Do the timing with a strobe if you can and check the full advance.

Hi diesel Dave, I have replaced the condenser with a new one to rule it out. I can try the strobe to check advance. Could you tell me how the 50cc engine advances the ignition because I thought it could be the centrifugal advance on the back of the flywheel but when I took it off to check the operation it doesnt have one fitted. Would a rebuild kit from a C50Z2 be ok to use on this bike and maybe fit a #78 main jet as the spec says that that size sgould be fitted and its what is in there already .
Simon.

Run the bike at a decent/fast idle. Spray WD40 around the inlet manifold and anywhere else you could possibly have an air leak.

It sounds to me that you have an air leak on the inlet tract somewhere.

If the revs increase, its sucking in the WD using it as fuel. You should be able to pinpoint the source of the problem.

Thanks for that suggestion I will give it a go tomorrow and report back my findings.

Hi I have ordered a new coil to see if this sorts the problem out. It is easier than trying to find a carb rebuild kit!! (C50zz) If that doesn't work, can anyone suggest where I can source a replacement carburettor with the correct jetting to fit this bike. I have tested for air leaks with WD40 but none found. Still bogging down and cutting out on wide open throttle. I still can't work out how the ignition curve advances on this bike.
Any help much appreciated

Simon

Allen's performance don't do a carb for this bike or a rebuild kit.
Simon