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Interesting one this -- got a series 3 Special with a standard 200 lump, 26mm jetex & clubman set up. Goes well & has good pull on it, it will start very easily from cold with 2 - 3 kicks and feels like good compression. When its hot after a good blast & a stop for petrol it feels like the kickstart is not turning the engine over enough to get a good spark and ignition. Bump start it & it goes like a rocket again. Any ideas on this?

The boys are getting pissed off giving me push starts -- G

Sounds like worn piston rings......

Ditto, check bore also.

Rings. Possibly seized in piston.
Sometimes will try to fire and feels like it's flooded?

Had mostly the same problems for years,not so much the compression,my choke cable was wrong,it was to short to be exact,no play in cable ment when I sat on scooter choke came on,wouldn't start from hot always flooded,took it to old school guy I knew,picked it out in 5 min after years of me trying everything,including rebuilding of engine and carb ect,I was a happy boy,

well its clearly heat that is causing this directly or indirectly. There cannot be much wrong with the compression if it starts and runs well otherwise I shouldn't have thought.

This is more likely to be a fuel/air problem I should have thought.

I would be looking at the fuel flow when the engine is hot. Whilst you are riding it the mag fan and airflow are cooling the engine but once you stop and switch off,.. the engine will actually get hotter just sitting there for the next 5 mins or so .
How hot does the carb get ? maybe the fuel in the carb or in the fuel pipe is evaporating and its only when turning the engine over quickly ( bump starting) that is drawing sufficient fresh fuel through ?

Had similar problem with mine when hot, if I turned fuel off and opened throttle full would start no problem. I put all Dellorto jets in the jetex and a new float needle and it's been fine ever since. Saying that though poor starting when warm can be a sign of worn rings or bore.

pip wrote:Had similar problem with mine when hot, if I turned fuel off and opened throttle full would start no problem. I put all Dellorto jets in the jetex and a new float needle and it's been fine ever since. Saying that though poor starting when warm can be a sign of worn rings or bore.

I'll try this 1st, change the air filter -- all the easy stuff before horsing into the piston rings / bore etc - Cheers for the help Troops - G

"Hot Starting" (not starting) is usually the choke. Check it's closing off fully. Although the lever may be closing, and the plunger dropping, it may still be allowing fuel to pass and flooding when warm.

Sure it's not the clutch slipping when hot ?

Wack wrote:Sure it's not the clutch slipping when hot ?

Pretty sure its not this -- when it does start (it always does eventually or after a bump) it goes well & pulls really hard with no lack of power or pull,

pip wrote:Had similar problem with mine when hot, if I turned fuel off and opened throttle full would start no problem. I put all Dellorto jets in the jetex and a new float needle and it's been fine ever since. Saying that though poor starting when warm can be a sign of worn rings or bore.

I've used this technique before --- next major run I'll try this - G

Try it with the bellows off could be spit back collecting in the rubber. pin hole in the bottom may help

another one to watch! mine was giving some symptons like this i.e a good first kick at cold them some softer like poor compression. it was a fresh build last year so was going to retorqe head and oil change but took the side off anyway as its a cyclone and need to be 100%. sure enough it was the old problem of kickstart/ top plate contactthis had already been a pain on first build with the cyclone/mb 5/6 plate clutch and numerous kickstarts, having settled on a ts made in italy, at the time the best option for li/sx type, but still ground down and built many times with black marker to test for contact. my main point is that although there is a usual contact point on a running engine that needs to be relieved as you kick over the rest of that boss comes into play and so slightly depresses cutch. which seems to get worse as the oil gets distributed and warm hence my posting here. i dont know how much more i can risk grinding away, probably need to do the case mod but that throws up more probs with kick shaft hitting the 3 ramp bolts. one to watch, good luck!