karl thomas

hi i have a ZENOAH 23cc its a very old one it has the square looking pull start but any way its not working
1, if i take the air filter off it blows the egsorst fumes back thow the carb
2, 25-1 fuel mixture allwase used
3, the egsorst seems fine not to rstricktive
4, if i hold the wheels off the ground and fold full thortal it will after like 10 seconds get above idle speed and then it seems to work then i drop the car and drive but if i stop it canot get moving
5, i have tried for 3 days now and canot find any think rong (i have tryed lots of diffrent needle stttings PS. i need the low end needle 1 of a turn out from fully closed just to get it 2 fire up
any one know why?
thanks karl


ps i have pics if needed

bsrman14

Rebuild the carb and reset the carb setting back to OEM settings to start with. Another thing you can do is use 32:1 oil instead of 25:1. Use can try newa spark plug. The list can go on and on.l

karl thomas

i have tryed all that meny times

karl thomas

when i take off the air filter it looks like its the egsorst enen thow the egsorst is not blocked???? the carb blows out almost evrythink

jimjeep

When was this engine last run?

If it was stored was it run empty first to keep it from gumming?

Check the ignition coil is not out of adjustment (or loose).

Have you performed a compression test on it?

Finally, with the plug out turn the engine by hand (you will have to remove your pullstart for this) turn it slowly a few times while looking through the plug hole with a small light and bring the piston to the top and just beginning the down-stroke. When the piston begins to move down stop and watch that it doesn't move. Take a wooden stick (a new pencil will do) and try to push down on the piston while holding the crankshaft still If the piston moves with the crankshaft still then there is a problem with the piston/connecting rod assembly (which could cause this type of problem). If this happens the engine would have to be taken apart and rebuilt.

While you're looking in there check for any black carbon build-up which could be causing a pre-ignition.

Good luck. [)]

da mad maori

quick test..... pull the "egsorst" off and try start it..

if that doesnt work then you call rule it out completely...

it has all the signs of exhaust restriction...

Ryan

TheFgMan01

Your coil is shot!! Happened to me, when i was trying to start my truck it would back fire also. Got a new coil plugs even stopped fouling and back fire problem solved o)

OLD_SLOW and in the WAY

the ring might be stuck from hardened goo and isnt letting compression build

badz

My Feedback: (1)

that'd be my guess too that or the top end is totally shot

karl thomas

ok give me a cuple of mins to test it

karl thomas

right the piston conncting rod seems fine good compression from what i think(it cannot lift the car up off the ground fg marder)
and the spark plus seems to be fireing correctly

karl thomas

ok i have gave up getting a new one (the new type of 23cc like you get with new marders today) im getting a used one off ebay nice and cheep

TheFgMan01

Why not just a Zenoah 26?

karl thomas

just muney in bidding on ebay for a 23cc at the mo is £33 and a 26cc wiout carb clutch ect is £15 so thats not bad
and the old engine now has no compresion at all so im scraping it