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No tickover Sh1/20

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No tickover Sh1/20

Postby aby » Tue Apr 21, 2020 1:00 am

Help please...
Finally got scoot li 150 started after rebuild fitted a New scootopia sh1/20 that was set up for a 200 but changed the slide for a 150 set up and atomiser to a 5889-4 with 102 main jet, choke 50, pilot 45.
When choke Is put on it revs fast.
Once warm I flick off choke and it dies, it will start again rapping the throttle open but if I can’t get the throttle opened up quick enough it dies again.
Set the air mix screw to 1.5 turns but to be honest when I can keep it going and I try to adjust the air screw to get it to idle it makes no difference. Tick over screw is slightly lifting the lever but again makes no difference wherever I set it.
Did a leak down test and all was ok
It has been strobed and set up to 19deg but not sure what revs we’re going through it as I just managed to keep the throttle open enough to get the strobe on the flywheel.( so presume reasonably high revs)
New BGM stator fitted and checked all seems ok, CDI is a Scootronics with leds, flywheel Indian but lined up all pickups to stator. Sorry trying to give as much info as possible.
So basically nothing at 0 to half throttle and cannot get it to idle.
Ordered loads of main jets ( from 90 to 110) also got a 41 and a 50 pilot if any would help and a few atomisers 5889-2 ,4 and 5.
One last thing the only place air is leaking is from the exhaust joint as I noticed fumes coming from there when I kicked it over exhaust is an AF rayspeed 42mm I have some sealant for that but not put any on yet.
Sorry to bore you with this one, just need a few pointers, I know it’s a bit of a science.
aby
 
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Re: No tickover Sh1/20

Postby Fast n Furious » Tue Apr 21, 2020 1:11 am

Sounds like a pilot jet issue.
With it being a new carb...... you might be unlucky enough to have a duffer?
Try a different carb if possible.
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Re: No tickover Sh1/20

Postby CHRIS in MARGATE » Tue Apr 21, 2020 11:20 am

Fix the exhaust leak first, you might be pleasantly surprised. You will never dial the carb in correctly if the exhaust is leaking.
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Re: No tickover Sh1/20

Postby bookertmgs1 » Tue Apr 21, 2020 11:48 am

As others have said - need to get it airtight first and then start looking at carb. Make sure the clamp is correctly positioned to aid the sealing process.

As an aside - there have been instances where the new Scootopia Carbs havent been right - the case I saw was a 22mm though - so if the leak doesnt sort it dont take the carb as as nailed on good 'un
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Re: No tickover Sh1/20

Postby aby » Tue Apr 21, 2020 1:26 pm

Cheers all
I will have another look later today and report back.
I noticed when searching info that lambrettaclubusa had tried to set up a spread sheet on their site so ppl could add what carb, jets, piston exhaust etc etc....they were using then you could check if you had a simular system to one on there to give a good starting point before asking loads of questions, I,m sure you guys get fed up of repeating the same stuff.
https://docs.google.com/spreadsheets/d/ ... edit#gid=0
Might be a good option some time
OH YES up or down on the pilot if it needs it after sealing the pipe.
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Re: No tickover Sh1/20

Postby Fast n Furious » Tue Apr 21, 2020 1:47 pm

The jetting you have is suitable.
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Re: No tickover Sh1/20

Postby CHRIS in MARGATE » Tue Apr 21, 2020 5:22 pm

Not down on the pilot.
Once you have sorted other issues then you should need choke to start. When the engine has warmed up and choke is off, then putting the choke back on should cause the engine to struggle and stall due to the over rich mixture.
The pilot circuit will be correct if when warm: you rev it up and release the throttle and it returns to a steady tickover without hesitation. If it stays high and is slow to return to normal tickover then it is most probably too weak in the pilot circuit. If it struggles to get back to a clean tickover, then the pilot circuit is too rich. If adjusting the mixture screw has little or no effect then the pilot jet is the wrong size and you will have to increase or decrease accordingly.
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Re: No tickover Sh1/20

Postby rossclark » Wed Apr 22, 2020 12:53 am

For the exhaust joint - if you mean the one between the U bend and the silencer then this has little effect on running / jetting. A leak at the cylinder / manifold gasket is different.
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Re: No tickover Sh1/20

Postby aby » Thu Apr 23, 2020 1:08 pm

Still having the same issue.
I have sealed exhaust (it was the joint between box and U bend I was on about) Made no difference
When it started I left it running for a good 5 mins before switching off the choke and it stopped, when I Kicked it over again without the choke it started, if I put the choke on it revved up it didn’t cut out.
Took carb off to check my jets and they were as had written, when I put it back on It would not start
so I fitted the old original sh1/18 carb which is 50 choke, 5889-2 atomiser with 105 main and 45 pilot ... would not start
Not sure where to go with it now
If I could get it started I would check my stator settings again but it was set up with a “buzzwangle” so pretty sure it’s correct. As I said before it’s a new BGM stator that read ok.
Could it be todo without piston rings but compression seems ok.
I have a Casa 185 kit I could put on but would need another carb for that....starting to become a nightmare :lol:
Good job I have another to ride on
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Re: No tickover Sh1/20

Postby CHRIS in MARGATE » Thu Apr 23, 2020 3:40 pm

The "buzzwangle" thing is only to set the timing spot on to the nearest half degree. I don't use one and for me it's not that important. Your timing if a few degrees adrift from various (and there are various) recommendations will NOT cause the problem that you are experiencing.
To test the stator readings you do it without engine running and with white red and green wires disconnected.
It can point to problems but these little gremlins tend to refuse to present themselves on a meter and then just when you think all is OK, fail when warm. That CAN be a failing Low Tension coil on the stator.

So you have changed carb and that eliminates that. Is fuel flowing freely. Run it off into a bottle and keep doing that for a while. Is it old petrol?

Now once you have 100% eliminated fuelling you are left with compression (need a compression test above 100 psi) and ignition. Only way to truly eliminate is to change out the stator.
I wish you lived nearer.
The leak between downpipe and box was a red herring. As stated it's the manifold that must be sealed.
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Re: No tickover Sh1/20

Postby aby » Thu Apr 23, 2020 8:48 pm

I have an Indian stator that I originally tried to fit but the slots wouldn’t allow me to get it round enough to line up with timing marks I have lengthened the slots Which only have about 2mm of metal left before I am right through. But when I first fitted it to try I couldn’t even get a splutter.
I might put the old exhaust back on tomorrow and just check the squish clearance again it was about 1.6mm, and while at it remove the cylinder and check the piston is ok, ie right way round and rings ok. Hope to get this all sorted before having to get back to work but at least it stops me getting bored at home. :lol:
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Re: No tickover Sh1/20

Postby Gerard » Thu Apr 30, 2020 10:03 am

Atomizer - Just to pass on a bit of information that I recently found out (thanks to Mike a member on here) and that might help …. but I can't see that apart from LI 150 you say if the scooter is Italian, Spanish etc. However, I am having a similar problem with a Servetta S3 LI 150 and have found out that the atomizer particularly for low revs is significantly different on the SH1/20 for the (Spanish) Servetta than it is for the (Italian) Innocenti. The standard setup for the SH 1/20 states atomizer should be 5899-5 but the Servetta uses a #6 atomizer which is actually closer in jet sizes to the 5899-2 I have yet to try this but will hopefully do it later today and will let you know.
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Re: No tickover Sh1/20

Postby Gerard » Thu Apr 30, 2020 5:11 pm

That didn't work... #6 atomizer actually made it impossible to start when it was even slightly warm :( was worth a try lol
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Re: No tickover Sh1/20

Postby aby » Thu Apr 30, 2020 10:21 pm

Final follow up to my problem, for some reason my leak down test did not pick everything up, my fault as it’s the first time I tried one. :roll: I completely stripped everything back today including the mag housing, left most gaskets off and just siliconed, apart from the head gasket that had Liquid gasket either side of the original one.( put this on to give decent squish gap 1.2mm)
Would not start on choke but straight away without, and after a couple of turns of mixture screw and tick over screw she is purring lovely with no spluttering.
Taking it on the road tomorrow because I think there’s a problem getting 2nd gear so a bit more tweaking then hopefully just the sloppy side panel handles to sort out and new headlight bulb and off we go. ( to the shops for that necessary journey) :D
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