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[iDENTITi]

I picked up a secondhand sovereign 30cc strimmer motor off eBay for £4the other week, had a bit of a fiddle though, stripped it down completely, and still can't get it to idle!
It will ONLY start with full choke on even when hot.  Idle is way high when taken off choke (clutch engages..) and when throttle is opened it dies (after cleaning it revs up to full and then dies after a few seconds).
Anyone got any suggestions? The carb doesn't look like it has any adjustment to me..

[poddy]

Sounds like a weak mixture. Maybe the carburetter jet is partially blocked? What colour is the plug? If it is glazed and or the electrode is melting, it would point to a weak mixture.

[iDENTITi]

plug is black, wee bit oily, normal 2stroke-ness.

[poddy]

Another thought. Do you have the air filter attached? Some small engines will run weak if they don't have the air filter in place

[Prophet]

bin it .. you will probably spend more time and money getting it to work then buying a cheap new one.....

[poddy]

lol, it's not weak then! but try running the motor flat out for a while and then check the plug

[Prophet]

only real suggestion i can offer is to strip it down to its parts and thoroughly clean it check the piston rings , dismantle the carb and clean and check , replace all the seals, check the clutch assembly to see if its jammed and preventing the motor idling i found that this happend to me once the pin that the clutch arm makes contact with was bent and pinned the whole assembly along with the clutch springs thast were over stretched. i could only start the engine via full throttle and even then i couldn't get it to idle...  

[iDENTITi]

only real suggestion i can offer is to strip it down to its parts and thoroughly clean it check the piston rings , dismantle the carb and clean and check , replace all the seals, check the clutch assembly to see if its jammed and preventing the motor idling i found that this happend to me once the pin that the clutch arm makes contact with was bent and pinned the whole assembly i could only start the engine via full throttle and even then i couldn't get it to idle... 

Done that, cleaned the carb, clutch is part of the flywheel and just acts against a spring holding the shoes together.. I'm at a bit of a loss... And it's for a boat, so if i bought new I'd be looking at £30-50 for a strimmer and £170 for a zenoah so.. Not really worth it.

[Prophet]

you want to check the clutch shoes tension ... if the springs have gone the shoes will open via centrefugal force keeping the clutch engaged at all times thus not allowing the engine to idle at all remember on the strimmer it would proably idle with the extra weight of the strimmer parts but with no other weight to slow down the clutch the springs are not strong enough to hold the shoes back in tension until your up on rev's

[iDENTITi]

Thanks for the help, I'm going to attack it with a spanner later and remove the clutch entirely.  I also had a bit of a "attack the main jet with a screw driver until it works" so half screwed it out, now idles with choke off and revs to about 3/4 throttle, past that and it bogs and dies... But couldnt fiddle any more because of the time.
Thinking a new carb might be in order...

[Bill D203]

OK.
Don't take the Cfc apart. You need to set up the engine 1st. It would be a big help if you can take some photos of the engine and the crab. Now dose the crab have 1 or 2 needles???? If it has 2 then is one for the low end setting and then the high end neddle takes over. How have you set them??? There is a way of setting the crab so it will start and run then it can be fine tuned from there.  If it only one Needle then there is a way to set that as well but I need a pic or 2 to see wot is going on.

[iDENTITi]

It'll be running with the clutch off anyway, its powering a jet drive so the clutch is a bit, useless.
I'll go down the garage in a bit and take a photo or two.
See, all this fiddling with modern cars has made me useless with carbs.

[iDENTITi]

[Bill D203]

Ah now that makes alot more sense.
It has got a single needle crab fitted to it. I have one just the same on a 23cc engine. Mine is set at 1 1/2 turns out. This means screw it fully in ,then screw it out 1 1/2 turns. Now then what oil petrol mix are you using? It says 40/1 on the engine. I run mine at 25/1 this gives it a bit more oil.
You can bolt a 257 crab on your engine these can be found on Ebay this has a 2 needle set up on this crab. I have been using 257 for a few years now.
OK the other thing you need to check is the block between the crab & the engine is straight. They do have a habit of distorting. This may be the problem. anyway best get off & let you check it out.
Bill

[iDENTITi]

Ah, That would explain it.  The mix screw was fully screwed in (came like that).  I tried in vain to find the proper set up for this engine, oh well.
Currently running 40:1 with some very stale petrol nicked from the mower (about 3months old..)
Going to get it running and then modify it for watercooling, if it will fit in the lathe. Some porting work may come along if I trust myself enough too!
Thanks for the hint on the carb, I'll look at getting one.

[Bill D203]

No probs. Im off to me pit now as i have an early start 5am Up to Brimingham then North Cronwall all in one day. Still I don't come back
till thursday.   

[iDENTITi]

You're a diamond mate, it runs perfect now! Idles low, might need to change that with it being hooked upto the jet but that can be sorted.
Now I think I'm going to have to remember my machining lessons and make up a water jacket... Haha