Scooterotica

I attempted a spin out today but ended earlier than expected!
Heard a knocking noise from the top end and the it wouldnt settle down when the throttle is released.

Got home and took the engine apart and found the following.

The top ring retaining peg on the piston as gone and the ring ends dont look to clever.
The barrel it self seems ok with no scores visable.
When I removed the crank on both outward sides of the webs there is a build up of what looks like black grease!.

Does this indicate that the oilseals are gone causing an air leaking making the mixture lean?

Obviously I'm going to replace both bearings, 3 x oil seals and a new piston/rings.
Question is which bearings/seals should I be using and second which piston should i get - An Asso or Wisco or one of Broadys Pistons?

Also should I be looking at changing anything else whilst the engine is apart?

Thanks

Check the big end aswell. I would try a wossner piston, as they are alot cheaper than most.

Another question!

Checking on Broadys website and there are 4 grades of piston - a,b,c,d.

How can i tell what grade I need?- is there some marking on the barrel that indicates what the grade of the barrel is?

Thanks again

Hi james,glad you made it back home . yes there should be a corrisponding a b c or d stamped on the barrel.

Got back ok - what do you reckon of that black sludge on the crank webs?
Shagged oil seals?

Gonna sort the bits out tommorrow so should be on the road by the weekend

Many there today?

I would recommend contacting Harry Barlow(Pro Porting) he was doing a bearing/viton seal set today at Kettering for £45 and were top quality. Not seen the Wossner pistons but can assure you the MRB ones are top notch and are unlikely to have the same probs as with the Asso brick.The black grease is probably a sign the seals have gone or someone was over enthusastic with the grease when fitting the crank. The cylinder size grade is stamped on the little flat joined to the head gasket face.

wack 63 wrote:I would recommend contacting Harry Barlow(Pro Porting) he was doing a bearing/viton seal set today at Kettering for £45 and were top quality. Not seen the Wossner pistons but can assure you the MRB ones are top notch and are unlikely to have the same probs as with the Asso brick.The black grease is probably a sign the seals have gone or someone was over enthusastic with the grease when fitting the crank. The cylinder size grade is stamped on the little flat joined to the head gasket face.

Ta mate, i've Harry's number somewhere,I'll give him a bell.

So MBD 's pistons are a quality bit of kit then ?

Thanks again

Yes, MB RaceTour pistons probably the best you can fit to a Lambretta. Just remember to check ring end gap at 1,000 miles, as MB says, as many pistons seem to be getting excessive ring end wear during running in.

http://www.forged-pistons.co.uk/
Wossner

Is the Wossner a cast or forged piston Dave?
I'm going the Monza piston with a head machined to suit myself.