Weird one!

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stonerosesmod
registered user
Posts: 78
Joined: Sat Nov 22, 2014 8:56 pm
Main scooter: Lambretta Li150S
Contact:

Had a bogging problem on my P2 for a while and can't suss it out.Bought the disc engine complete and stripped it three times with new bearings and seals properly fitted with yamabond.No damage to the casings and no leak from behind stator.
Symptoms are when the scooters on its side stand or sat upright,it will bog when you blip the throttle,sometimes enough to make it stall.Lean the scooter over to the right and it will rev normally!

Cleaned out jets,
Tried new carb with new jets,
Mix screw makes no difference
New SIP fuel tap with new hose,
Cap off fuel tank,
Tried new plug,cap,HT lead,
Changed Cdi,
Tried another stator,
Changed floats,no kinks in fuel pipe which was shortened

Plenty of fuel getting to carb,good flow but only revs ok when leant over to the right :(

I've rebuilt a few PX engines but this one has got me beaten.Only thing I haven't tried is another flywheel.

Anyone have any ideas?
oldbiker
registered user
Posts: 194
Joined: Wed Jun 17, 2009 6:21 pm
Location: Aintree
Contact:

i had a similar problem with my 125 using a 34mm amal i upped the pilot jet one size then altered the tickover and air scew and that sorted it out, still don`t know why it was so sensitive to the angle of the scoot
Jack221
registered user
Posts: 214
Joined: Mon Jul 29, 2013 8:18 am
Main scooter: PX221
Location: London
Contact:

A lot of work you have done for what sounds like a jetting problem. What pilot jet is in it now? If is starts and ticks over ok then its normally just the big number of the pilot jet that is too big.
Vespa est ieiunas, quia semper operaturi
stonerosesmod
registered user
Posts: 78
Joined: Sat Nov 22, 2014 8:56 pm
Main scooter: Lambretta Li150S
Contact:

55/160 as a standard P2,but why would it only rev clean leant over to the right?
paul d
registered user
Posts: 305
Joined: Thu Jun 30, 2011 10:00 am
Main scooter: T5 172 Tv 240
Location: Galway Ireland
Contact:

I wonder is it electrical? Might be worth disconnecting the outer green wire from the cdi. It would rule out anything shorting in the frame.
Jack221
registered user
Posts: 214
Joined: Mon Jul 29, 2013 8:18 am
Main scooter: PX221
Location: London
Contact:

Probably because the float bowl level will appear to be higher for the jetting. Try a 55/100 if you are running with no air filter
Vespa est ieiunas, quia semper operaturi
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