Strange behavior of my Lambretta after riding ca 20minutes

[bristolmod]

I had a similar problem on a TV175S3.

Had to replace the main oil seal and upon striping found a very thin "shim" between the crank and the main bearing- in my ignorance I assumed it was part of the seal that had broken up.

Rebuilt the engine with new seal and didn't give ant thought to the "shim" that had fallen out.

Had exactly the same symptoms as you- when the engine got hot the expansion caused the crank to run against the bearing/ seal plate are and it would eventually stop. 20 mins later it would start again.....This "shim" obviously allows some clearance in that area.

Odd thing was, there is no mention of this shim in any of the original parts books, but upon investigation, I find that MB do in fact sell them. You learn something every day in this game!

Chris

[kejj]

Bristolmod: interesting. Never heard of that shim before. My engine is a rebuild SIL GP200. Therefore a GP crank is being used (Indian webs, japan rod and bearings).

the problem here is that the stator green gives very low values when measured. And the fact that the problem becomes worse over time points that with the heat increasing the stator gives up.

Stuck piston rings would show a problem when cold starting.

Other possible error would be air leak. Although I haven't done a leak down test I have blocked the exhaust and it kills the engine.

Thanks for the advices I will start with the stator and see were it takes me. Still believe the stator, cdi, spark is causing the problem.

[kejj]

Where the problem came from




In iron Lambretta cylinders we trust!

[fastfrog]

Definetly the stater breaking down I had similar a few years back..

pick-up's dead.

[Architecten]

There appears to be no earth from the pick-up?! Or are we looking at the mangled loom??

[kejj]

So for clarification issues.
What we see in the above picture is a mangled loom.
The stator is a DC modified Indian one. It had been run for a while in another engine were it run fine. The engine case was a LI 150 S3 and the fly wheel was a SIL with shortened fins.

I decided to rebuild 2 engines and swap some parts, the LI case gave room for a TV175 barrel and crank plus AC stator.
This engine is a SIL200 one I purchased years ago (2006). The flywheel was the lightened SIL Flywheel with shortened finns.
In this engine, obviously the stator did sit back enough so the cable retained slipped on the fat loom and the flywheel came to close to it causing the meltdown of the loom.

The scoot started and idled because when cold and on low revs it was able to transfer power through the damaged loom. When I tried to rev up and away it gave me too little power and in bursts. This was evident when I measured and found the resistance very low.
The interesting thing is that the flywheel never watched the pickup.

The SIL stator is still working and is repairable if I manage to resolder new wiring to it.

I changed to a BGM stator and a MB cable retainer, checked clearance and everything is OK now and has been for 300km.
So it's officially running in time!


In iron Lambretta cylinders we trust!