Starting Hot

[davej]

Suggestions please:-
Have put a Mugello 200 kit on a 150 casing, Starts cold fine, when running plug colour good, however stop and will not start after 5 mins or so!
Carb set up:
Jetex 22
Starter 50
Pilot 45
Main Jet 118
Atomiser Allstyles modified
Foam Filter
Ancellotti Exhaust
Any suggestions to solve the 'hot' starting would be apprieciated
Thanks

[MickYork]

choke sticking. Maybe not fully open but only partially closing.

or

Fuel collecting in bellows. Put small hole in the bottom to allow fuel to drain.

or
...........other

[johnnyXS]

does it smell like its being over-fuelled when hot starting ? have you checked the plug after trying to start it ?
I'd try start it next time with the rubber hose off so that you can see if the carb is flooding . You might need to fine adjust your float assembly if you haven't already done so as the Jetex are notorious for being supplied with poorly fitting float/pivot/stanchion fitting.

Lastly I'd try find out what the Allstyles atomiser spec is . I find it inexplicable that they supply Atomisers with no detailed spec as to the bore dims and that of the air holes etc .How are we supposed to tune a carb when you don't know the jet or atomiser sizes !

[coaster]

This subject crops up regularly and as Mick says, the immediate cause is fuel being 'spat back' which collects in the bellows and causes the engine to bog when starting. Spit back is present in all 2 stroke engines to some extent due to overlapping port timings which is more prevalent with tuned barrels. Other factors can also come into play such as the choke not fully closing as mentioned by Mick. The isle jet/airscrew will also have an effect so would be the first thing to play with.

One trick though is to always turn the fuel off around 10 0r 15 seconds or so before turning the engine off. If starting from hot, leave the fuel turned off and keep the throttle closed when you kick it over. This usually works and you can turn the fuel back on as soon as it fires up. Plenty of owners have learnt to do this. The issue about keeping the throttle closed for starting applies in any case.

[Meds]

I have had similar problems in the past and worked round it using Coasters method.
The underlying fault in my case was timing. It was only found when a mate strobed the engine and found the static timing marks and firing point were 3 degrees different.

[Tractorman]

I have had similar problems in the past and worked round it using Coasters method.
The underlying fault in my case was timing. It was only found when a mate strobed the engine and found the static timing marks and firing point were 3 degrees different.

I will check this with mine. The special with a mugello 186 starts well whereas the S2 with the mugello 225 has the hot starting problem. I try and remember to turn the fuel off but often forget

[davej]

Thanks Lads, Plenty to check! Couple of points
Timing is right I've strobed that
Allstyles Atomiser - They drill out the bottom holes to 0.7mm

[Andie]

Hello. i recently posted about potential spit back problem with sealed 22mm bellows.
I would ideally like to enable a 22mm bellows to have a S3 18 or 20mm one way valve present (so as not to muck about with air intake source).
Possibly one for after-marketers to look at as I think there is a demand.

However - A few people suggested ways of making a drain in the sealed hose. I'm told it seems to work.

All the best, hope you sort it.

[JETEX]

I would have thought that a 118 main jet is far too small for a 200 cc engine, especially if you're running a large bore exhaust. Sticky recommends a 123 jet for a stage 4 Indian barrel. I bought a brand new Indian GP 200 engine and fitted it with a 22 mil Jetex and 42 mil Clubman exhaust. The carb came with the 118 main jet. It put a hole in the piston coming home from the Irish Euro. I now run it with a 125. A little bit too large perhaps, but no more problems with the engine. It's been around Belgium and Holland with this set up.

[Tractorman]

Hello. i recently posted about potential spit back problem with sealed 22mm bellows.
I would ideally like to enable a 22mm bellows to have a S3 18 or 20mm one way valve present (so as not to muck about with air intake source).
Possibly one for after-marketers to look at as I think there is a demand.

However - A few people suggested ways of making a drain in the sealed hose. I'm told it seems to work.

All the best, hope you sort it.

Tried that but it did not work for me.

[HxPaul]

A friend of mine runs a 175 iron cylinder with a clubman exhaust.He uses a jetex carb through the airbox with a 125 main jet and a 48 pilot jet,the scooter runs great.

[pip]

Had plenty of trouble with hot starting with jetex carbs and found winding throttle open with petrol off before starting usually worked.

[Granty]

Had plenty of trouble with hot starting with jetex carbs and found winding throttle open with petrol off before starting usually worked.

That's the technique I have to use on my 200 pump with a jetex carb, works every time G

[bigbthesoulman]

Had problem for years,tried everything ,even enginer rebuild,New carb the lot,took to old boy I know workedw ith Lambretta s years ago,phoned me up wrong choke cable,was to short,when Sat on bike put it on,no free play,and bigger pilot jet he said,I have never looked back,standard 150 set up with 20 mm Dell mind you

[johnnyXS]

Had problem for years,tried everything ,even enginer rebuild,New carb the lot,took to old boy I know workedw ith Lambretta s years ago,phoned me up wrong choke cable,was to short,when Sat on bike put it on,no free play,and bigger pilot jet he said,I have never looked back,standard 150 set up with 20 mm Dell mind you

Yes I spotted this problem myself. i had a helluva job fitting my new choke cable to my 64 Lis150 . it was so short I ended up having to shorten the brass choke cable bend by 3/8" in order to get a little slack otherwise the slightest movement in the carb or choke cable unseats the choke valve .
Its worth getting someone to bounce the scoot whilst you check that the choke cable doesn't get pulled by the suspension travel too.

[TS1-200]

Sometimes hot problems can be down to worn rings, and also slightly loose cylinder head nuts, if all else fails have a look at your top end