GP won't start

[SILGP]

Hi, can anybody help ? I had a dodgy thread on one of my exhaust studs so a mate had the head & barrel off for that to be sorted. Since it's been put back together i'm having trouble starting it. My mechanic skills are very basic but I have checked for a spark & fuel & compression is good. My choke appears to be operating as it should and nothing has been touched on the carb which was all set up on the dyno at chiselspeed. Before the head & barrel came off it would start first or second kick. I don't touch the throttle when starting and have tried it with petrol on & off but no success. The only way it will start is by bumping it. Also my mate said the piston rings were fine.
It's a 225cc with a 30mm dell'orto carb & a sterling exhaust.
Any suggestions ?

thanks in advance.

Tony.

[MickYork]

Possible air leak.....worth doing a leak test......do a search plenty, on informative threads on leak testing.

[Rich Oswald]

Did you take the piston off and if so has it gone back on the right way round?

Rich'

[SILGP]

Thanks for the replies.

Rich , the piston was left in situ so it's not that.

cheers

Tony.

[missing lynx]

were the head and base gasket replaced and is the exhaust gasket the right way round?

[Mike Davis]

Possible air leak.....worth doing a leak test......do a search plenty, on informative threads on leak testing.

Leak down test as Mick suggests for sure, also if you can check compression, saying its good of the kickstart isnt good enough, youll need a proper gauge, if its around the 120 psi or less mark, thats your problem, which could be a leak or rings, wants to be a good 140 psi plus to start well on Kickstart.

[kennystag]

Sorry to jump in but 90 PSI would be a good enough to run a lammy engine.
Stag

[CHRIS in MARGATE]

Mine is 105 psi hot and cold and starts and runs sweet.
(Touch wood!)

[kennystag]

Yes Chris,
My GP starts first or second kit, runs really well, at 90 PSI cold, 90 PSI is a not a bad deal on a lammy, or any small engine for that mater. It should start at that PSI .
Cheers
Stag

[SILGP]

Thanks again for the replies. I'm gonna borrow a gauge to test the compression next week. I'll let you know the outcome.
cheers !

[SILGP]

Hi again , just done a compression test and the results averaged around 130 psi so from what has been posted earlier that is acceptable. It still wouldn't start though but then I remembered something about covering the carb when kicking it up. I tried this and it started for a few seconds & then died. Does this mean a blocked jet or something more serious such as an air leak as suggested earlier in the thread ?

Cheers.

Tony

[MickYork]

ok. Now you need to post your carb jettings (pilot, slide, needle, main, etc) settings, also your stator/timing settings (did you strobe these?)

[kennystag]

Hi SILLGP,
Take the carb off and clean it out the jets with jet cleaner and compressed air. When you are in there check the inlet manifold nuts are tight, and there is no other air leaks around the induction side. Just make sure your choke is working properly when you build her back up.
Good luck
Cheers
Stag

[Paulnobodyimportant]

I recently re-built an engine and it would not start, even with bumping off. I had spark but spark plug was fairly dry. Checked fuel flow to carb, which was OK. Therefore suspected an old Jetex carb that I had put on. On stripping, I noticed that the choke jet looked like it may be slightly gunged up. To err on the cautious side, I put in a new choke jet and it started after a few kicks and has consistently kicked over since.
I note that you have had your carb set up, but some dirt may have blocked your jets during the re-build, so as others have said, give it a good clean out, because its these little things that get us stumped.

[SILGP]

Thanks again for the replies. I am gonna clean the carb out this week and see how we go from there. Keeping it as simple as possible as long as I can !

Cheers.

Tony.

[SILGP]

Well , I wheeled the scoot out of the garage yesterday to clean the jets & thought i'd give it a kick to see what happens - it starts first time & ticks over nicely. Decided to check the jets anyway & they were all fine. Kicked it up again and it ran fine again. left it a few hours and it started on the 4th kick.
Don't know what's happened but i'l continue to start it every day & see how we go on.
Lambrettas eh !!!

[kennystag]

Good new then. Yes it is amazing what a kick will do, I thought abbot trying that with the wife, but she would kick me back lol.
Cheers
Stag

[SILGP]

Ha , nice one Stag. Re-reading it , it does make it look like i was doing a Basil Fawlty !

[kennystag]

Hi SILGP,
Is she running ok now.
Stag

[SILGP]

Hi Stag , sorry for the late reply , been busy decorating. Not had a run out yet but have successfully kicked it up everyday - Hoping to get out for a spin at the weekend.

Thanks for your (and everybody else's) help.

Tony.