SIL 200 bad starting when hot??

[Scootermonkey]

Opinions on this one guys. Standard SIL 200 engine, starts ok when cold. As soon as it gets hot, it's a ba**tard to start. Checked the usuals. Tried three different carbs, including a brand new Scootopia one. Checked choke cable fitment. Air filter etc. Seems to like spitting plenty of petrol out. I think the bore/rings are worn. It's done near 9000 miles. Barrel has been off some time ago and there were slight heat seizure marks on the piston. Any suggestions??

[Chris in Margate]

Compression test first.

[kejj]

I'd say rings!


In iron Lambretta cylinders we trust!

[Mr G in NYC]

^^^^^^^^^^

what he said G.

[Darrell Taylor]

it will like the extra richness for cold starting but not for hot starting ,if you turn fuel off before turning engine off and blip a few times to run fuel level down then start it up with fuel still off/the choke off and a quarter throttle to admit a bit of air will help alot ,,also what rubber bellows have you got ,has it got a breather to drain off the excess fuel like some of the originals have , that fuel gathers at the base of the rubber and does the same as the choke,it richens up for cold starting but not good for hot starting

[cgt75b]

it will like the extra richness for cold starting but not for hot starting ,if you turn fuel off before turning engine off and blip a few times to run fuel level down then start it up with fuel still off/the choke off and a quarter throttle to admit a bit of air will help alot ,,also what rubber bellows have you got ,has it got a breather to drain off the excess fuel like some of the originals have , that fuel gathers at the base of the rubber and does the same as the choke,it richens up for cold starting but not good for hot starting

Great advice!

[Scootermonkey]

Yes, that is good advice, but the spitback is excessive, in my opinion it shouldn't be throwing out that much fuel in the first place. What would cause so much fuel to be forced out of the carb? I know for certain it's not a sticky float

[Darrell Taylor]

try the mix screw ,ignore the sticker range ,often needs more than stated

whats the engine history prior to this event any changes made

[Scootermonkey]

Tried three different carbs on it, still the same problem. Engine is completely standard, but the top end was removed some time ago, basically for a check up, and there were some light heat seizure marks on the piston then. Been hard to start pretty much ever since then

[Darrell Taylor]

heat seizure marks ,,so was the rings free and not stuck in there grooves ,did they spring in and out ok