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Twisted crank?

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

Twisted crank?

Postby DaveTomo » Mon Jun 16, 2014 8:38 am

Recently had a blown drive side oil seal, changed the 2 seals & also the drive side bearing (not the mag house) also while taking the crank (SIL webs RB conrod) out it rolled off the bench :roll: :x crank looked to be OK. Put it all back together slight rubbing on the flywheel touching the stator, fires up & goes but stutters & farts at full chat. Put another flywheel on the same :cry: So what do you reckon twisted crank? or due to not changing the mag bearing? Either way I'm going away next Thursday on it (not the Euro , to the Isle of man) & have got to get it sorted before then, no one local to check the crank.
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Re: Twisted crank?

Postby Adam_Winstone » Mon Jun 16, 2014 2:00 pm

Good luck with it and hope to see you on IoM :)
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Re: Twisted crank?

Postby Scooterlam » Mon Jun 16, 2014 9:05 pm

DaveTomo wrote:Recently had a blown drive side oil seal, changed the 2 seals & also the drive side bearing (not the mag house) also while taking the crank (SIL webs RB conrod) out it rolled off the bench :roll: :x crank looked to be OK. Put it all back together slight rubbing on the flywheel touching the stator, fires up & goes but stutters & farts at full chat. Put another flywheel on the same :cry: So what do you reckon twisted crank? or due to not changing the mag bearing? Either way I'm going away next Thursday on it (not the Euro , to the Isle of man) & have got to get it sorted before then, no one local to check the crank.


Where are you,
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Re: Twisted crank?

Postby DaveTomo » Mon Jun 16, 2014 10:09 pm

Cheers Adam & Scooterlam, I'm in Shropshire , but after a frantic few hours this evening have discovered the cause.Checked the crank with stator and flywheel removed, no visible sign of it being on the p*$$, no movement in the mag housing,bodged a jig together and turned the crank to see if it ran true or elliptical /egg shaped rather than round,not very scientific but its worked before when I had a twisted crank.Decided to measure the new stator with vernier calipers, new stator plate is 0.51mm bigger across the diameter than the SIL stator it replaced ,put the back up SIL stator back on,no rubbing,re-set the timing took it out for a spin, no stuttering & farting :D :D Cheers lads & thank you ,till the next thrilling episode :lol:
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Re: Twisted crank?

Postby gaz_powell » Tue Jun 17, 2014 12:06 am

wey hey another SIL stator saves the day ........still my favourite !!!!
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Re: Twisted crank?

Postby Adam_Winstone » Tue Jun 17, 2014 9:19 am

^... still very good in my opinion too... but only if you change out the LT coil for something better (too many failures for too many people, too frequently). Most people locally that have 'bigged-up' the virtues of SIL/Indian stators have since had to replace LT coils or have suffered repeat failures and made the change to BGM :oops:

I do agree with people sticking with what they know and like. If Indian stators serve you well, stick with them.

Adam
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Re: Twisted crank?

Postby HxPaul » Tue Jun 17, 2014 1:04 pm

Adam_Winstone wrote:^... still very good in my opinion too... but only if you change out the LT coil for something better (too many failures for too many people, too frequently). Most people locally that have 'bigged-up' the virtues of SIL/Indian stators have since had to replace LT coils or have suffered repeat failures and made the change to BGM :oops:

I do agree with people sticking with what they know and like. If Indian stators serve you well, stick with them.

Adam

Which LT coil would you change to and would you change the pickup as well ?

Paul
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Re: Twisted crank?

Postby Adam_Winstone » Tue Jun 17, 2014 2:04 pm

Others complain of pickup failure but I've yet to come across one.

I try to pinch LT coils off Vespa stators or I use the BGM replacement LT coils. The one thing that is a bit of a pain is that the laminate core is a different thickness to the SIL stator base, which means that you need to modify the laminates accordingly. It is a bit of a faff but it does (IMO) leave you with a far superior stator.

Similarly, I've recently learnt of people starting to suffer LT coil failure with the Indian PX stators that have become more common since being available cheap on Ebay. Indeed, I've even started to repair the odd PX stator :roll:

Adam
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Re: Twisted crank?

Postby gaz_powell » Tue Jun 17, 2014 5:07 pm

Not wanting to hijack but I always use genuine SIL pick ups and LT coils (with success - my only failures have been an unbranded LT coil in the early days and a broken solder) but i have a rebuilt one vespa parts

Funnily enough I had occassion to use a SWISS branded stator on my P2 and found it to start and tick over okay but on the road it was like having a rev limiter - it just would not pull high revs - all the readings check out very well. Another strange thing was I have a digtal rev counter that was perfect before the SWISS stator - with the SWISS it was all over the shop (24,000 revs at 45mph !!!! then down to 640 etc )

Put a rebuilt italian one on and hey presto all good again

The joys of scootering !!!
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