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Good vibrations (not!)

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

Good vibrations (not!)

Postby DaveTomo » Sat Sep 22, 2018 3:56 pm

Went to Belgium last weekend , about a 700 mile round trip for us. The only thing was the vibration, doing other runs this year hasn't been so bad maybe a little tingling in my hands for a while after riding, but this time 4 days later ( got home Tuesday) my hands are still tingling/slightly painful.Possibly carpal tunnel has kicked in- I don't know.
Anyway I want to reduce the vibration and looking for some help :) At present I have a scootopia engine mount on the mag house side and the double type on the kickstart side (both fitted in the last 6 months), I'm going to change these over the winter for the BGM type- had these in before and lasted 5 years and I don't remember the the vibration being that bad with them.So hopefully that will help.
Also at present have the full MB headset kit ( the brass bits) which supposedly help with vibration, mine is a late SX headset similar set up to GP, the MB bar end weights and Oxford fat grips. Looking again over the winter to change the grips for Beston grips, as used on Triumphs , similiar to Lambretta balloon grips , again hopefully that will help. Also I'm thinking rather than the MB bar ends which aren't really a weight as they are hollow , maybe put in some brass/ steel rod into the end of the handlebars of a similar length??
Lastly - the engine is a Rapido 225 with 58X107 crank ( AF type , Indian webs and a RB conrod, pretty sure its not twisted, scoot runs fine and had it checked by AF at the end of last year and came back as being OK) Would a longer stroke crank make the engine smoother? I know I would have to use a packer plate.Is it a case of longer stroke or is it a combination of the webs as well smooths the engine out?. My thoughts thus far are either SIL GP200 crank with Yamaha 110 conrod or one the GT cranks 60X110. Any advice much appreciated, thankyou.
DaveTomo
 
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Re: Good vibrations (not!)

Postby NorthernJordan » Sat Sep 22, 2018 4:59 pm

Hi mate,

I'm young (25) and found the scootopia mounts way too hard and made the vibration way too much. So I would suggest putting the BGM ones in as I've found these to be reasonably smooth.

Re the crank, a longer stroke would make the vibrations worse. It's the length of the rod that helps balance out the stroke that increases smoothness of the engine. So I would look at having your crank built with a 110 rod or possibly a 116 (as per the TV). However. That would require a piston change also and I am kit sure what options there are.

It might be worth exploring bar end weights and other such modifications before going down the route of a new crank etc.
NorthernJordan
 
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Re: Good vibrations (not!)

Postby Storkfoot » Sat Sep 22, 2018 7:03 pm

The “new” Scootopia mounts are good. I have them now on my TS1 and no such problems. But, vibrations can come from all over. Do Mb bar end weights work?
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Re: Good vibrations (not!)

Postby holty » Sun Sep 23, 2018 9:58 am

i had big vibration problems on my lammy 290 (64 stroke 76 piston) when i built it , it was so bad i could only do 50 mph in top gear before i got white knuckle, i swapped my engine mountings for a sill gp mount on one side and a used af wide mount on the kickstart side, and problem solved, nice and smooth, so i would change your mountings
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Re: Good vibrations (not!)

Postby DaveTomo » Sun Sep 23, 2018 1:00 pm

Thankyou chaps, for the advice & also the PM's.
First off I'm going to change the engine mounts probably either SIL or UNI mounts.Like I say at present have a scootopia on the mag side and AF wide on the kickstart , both fitted in the last 6 months.The scootopia one on the mag side is one of the newer ones- or so I was told when I bought it.
Next will be get the crank rechecked again, with a veiw of possibly getting a jap rod conversion. The following from PJME website "Even 1 tho out of specification will cause vibration" They are only about 20 miles down the road from me in Wolverhampton so will pay them a visit.
The MB bar ends aren't really a bar end weight as such as they are hollow https://www.lambrettaspares.com/spares/headset-spares/lambretta-headset-(handlebar)-bar-ends-series-3-alloy-anodised-black-pair-mb/mrb0797.html so will be looking at, once the above is done, at maybe getting a steel or brass plug put in the end of the headset.
DaveTomo
 
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