200 Replacement Cam.

For 125, 150, 151, 200 cc Geared scootters

Moderators: ElbowNi, Geezer, tipper, Tony

200 Replacement Cam.

Postby tipper » Wed Jan 23, 2013 8:56 pm

Been having a nosy around the Italian LML forum this afternoon,there are a load of interesting posts over there about 4T''s,jetting and modifications.

One particularly interesting post is about the 200 starting problems and the replacement cam shaft.

The link to the thread is here http://www.stardeluxe.it/forum/index.php?topic=8703.0 google translate isn't perfect but it does a good enough job to get the gist.

Here are a few pics of the cam shaft,

Image

Image

Image

Image

Image

Image

Basically in idiot terms what happens is when the cam spins below 800 rpm a little lever pops up which holds one of the valves open which in turn lowers compression enough for the starter motor to have sufficient power to turn the engine over. Once the engine has fired up and is turning over faster that 800 rpm the centrifugal force or the cam spinning aided by that little spring retracts the little lever thing which in turn closes the valve and returns compression back to normal.

When you start the 4T up you can hear the little lever thing clicking open and closed as the engine spins.

Its a clever idea and it works but LML released it pretty damn quickly and there was no way they could have done any substantial testing and there is something about that tiny little spring that worries me.

I am no 'springologist' but I do know that the more times springs are stretched and then contracted the weaker they become.I know the spring is only under stress for a few seconds when the engine is starting up but I wonder how long this little spring will last before it loses its springiness.

Does anyone know of any other engines that use a similar system ?
Image
User avatar
tipper
Site Admin
 
Posts: 7767
Joined: Wed Jan 27, 2010 8:57 pm

Re: 200 Replacement Cam.

Postby Grayspeed » Wed Jan 23, 2013 9:27 pm

'springologist', like it! I don't know of any other engine that does it that way but I wouldn't be suprised if its a common thing. Springs last for quite a few cycles, just think how many times a Lambretta gear change spring works before they go too weak to hold the cursor in place.
Website: Click Here

We can be contacted on here or by email at info@cornwallscooterparts.com or on 07876197426
For all your LML parts, servicing etc. Sip and VE stockists, tubeless rims and tyres a speciality.
User avatar
Grayspeed
Member
 
Posts: 184
Joined: Sun Dec 18, 2011 5:32 pm

Re: 200 Replacement Cam.

Postby Tony » Wed Jan 23, 2013 9:35 pm

I think modern springs maintain their springyness for ages Tipper....new metals.....new springs with more springy ....but hey it's an lml....who are we kidding :lol:

Maybe they got the idea from this bloke

Image


Remember him ? :D
Image
User avatar
Tony
Site Admin
 
Posts: 6683
Joined: Sun Jan 17, 2010 10:40 am
Location: Fort Augustus
Scooter: 2009 LML Via Toscana
1986 Vespa T5 Mk1
1982 Lambretta GP 200
1959 Vespa VBA 150

Re: 200 Replacement Cam.

Postby tipper » Wed Jan 23, 2013 9:37 pm

Tony wrote:
Image


Remember him ? :D


Is he a springologist ?
Image
User avatar
tipper
Site Admin
 
Posts: 7767
Joined: Wed Jan 27, 2010 8:57 pm

Re: 200 Replacement Cam.

Postby Tony » Wed Jan 23, 2013 9:48 pm

One of the best I heard ;)
Image
User avatar
Tony
Site Admin
 
Posts: 6683
Joined: Sun Jan 17, 2010 10:40 am
Location: Fort Augustus
Scooter: 2009 LML Via Toscana
1986 Vespa T5 Mk1
1982 Lambretta GP 200
1959 Vespa VBA 150


Return to LML 4 Stroke - Geared / Manual Scoots

Who is online

Users browsing this forum: No registered users and 1 guest