ok guys, a little help please, i am running a alpha plus s852, and just swapped it into my new cobra, from an xray. now i cant get it to stay running at all. it will just run with the glow start on but thats about it. i have had to turn the carb the other way round, but i havent changed the settings at all. slide is still open about 1 mm on idle but the base settings havent changed at all. i am at a bit of a loss and cant even find some base setting for the carb, been running 4 on the main and 3 on the low speed.
i have changed the plug, and there is still good compression, but for the first time i have a awful lot of fuel coming out of the car after i have tried to start it coming out of the exhaust, any help would be appreciated.

if it runs with the glowstart on only then id say its the glowplug, maybe u got 2 faulty plugs?

whats the temp outside and what plug are u running?

im thinking if its not the glowplug lean it up, ALOT.
when a nitro motor, or any 2 stroke is too rich, when u apply throttle it boggs up and dies, and it doesnt run unless an igniter is in.

p.s. congrats on ur first post!!

many thanks, i will try that, checked the glow plug and it seemed fine, so it looks like the leaning route for me. just seems strange that it takes the glowpug to run and i havent had any trouble with it before swapping the carb round the other way.

swapping the carb shouldnt effect it.  Unless during the swap you damaged the o-ring or dont have a good seal anymore around the carb neck and too much air is getting in....May check that o-ring if you didnt before you tightened the pinch bolt..and seal the necessary spots.

+1 to rich settings puttin the glow plug out.....when the glow starter is taken off the glowplug, if the mixture is too rich it floods the plug puttin it out.  try to find factory settings and start from there......if its still too rich to keep the glowplug lit w/o the ignitor...lean the lsn until it will stay running w/o the ignitor. 

ok just tried again, and it just goes to rev out of control without any throttle and then flames out and dies, every now and then the idle goes stable but it still just wont run without the ignitor on it. dont seem to have an excess of fuel any more, just the occasional flame out from the pipe. i did check the seal before i put it back in and used some high temperature silcone sealant around the carb shank so i dont think its a air leak.
thanks for the help guys i am supposed to be running on sunday its the cobra's first outing and i would like it to be at least running.

UPDATE

still no joy, gone from super rich too super lean, on the lsn and nothing seems to make a difference it starts sort of revs for about 2 to 3 seconds and the dies. once every 10 goes the idle goes stable for 5 seconds and then dies, and then it starts all over again. at a complete loss.

the occasional flame out the carb!!? :O i never heard of that before, but my guess is bad compression, thats the likely factor of the engine not being able to hold a tune. put foam soap aroung the head of the engine and try to tell is there is no head gasket/ a loose head.

a few weeks ago i had this problem when i got bad compression on this 2 stroke 43cc pit bike i built. of course the fuel feed system is a lot different than a nitro, but it ran sometimes, but wouldnt idle and ran extremely poor, bogging and going very lean, and barely able too keep running, although the head gasket is located under the piston, not at the top. it just got worse and worse and after much frustration i finally resorted to checking the compression, and now it starts on one pull and i cant stall it if i tried.

nitros made in the 21st century dont use piston rings, so if it is bad compression and not leaking at the top you need a new piston and sleeve..

good luck!

also i forgot to specify the foam soap is to see is its leaking, so if it bubbles as the motor cranks then there is a leak and there is your problem. if its hard to tell, put your finger over the glow plug hole and try to tell if there is high pressure, likely you will not be able to seal it with a finger.

many thanks for all your help, tried the soapy water trick and found out it wasnt leaking via the head, it was a air leak around the main needle, who would have thought it
slid another o ring in place and there it went as good as gold.

just wanted to say thanks, me and the cobra are very thankfull.

Mark

awesome! glad it works. no problem.