Scooterotica

I should have my first lambretta engine running this weekend.

It's a gt186.

I've used rich Taylor's jetting advice plus a little bit so that I'm slightly rich.

I'm not sure what to do about oil. Do I go 4%?

I've also been advised to use mineral oil during running in.

I appreciate that there are opinions aplenty on subjects like this, but I'd like to hear them anyway.

Have a look on rich Taylor's website, granturismo. There is a section on running in. In my experience he is pretty meticulous in providing a piston to cylinder bore that is not too tight. I have always just used 3% semi synthetic. The important issue , which Rich alludes to on his site, is the way you ride it for those first 250miles.

I ran my Avanti in using 4% and "gunged" up my rings. I now run 2%..........sometimes more is less.

No 2 engines are the same and the riding style can also effect the engine. I would suggest 4% is too much and would aim for 3% or under.

I was told mineral oil by an old school scooterist whilst a dealer said no....

Go with any advice Richard gives you for his kit. Oil is the old his favourite/her favourite . Some oils are known to gum up rings. Ive always run a finger of neat oil on the bore when building a motor and stuck to the same oil when running in or after that period, which for me would be me favourite fully synthetic. I use 4% mix and never have issues with gumming or deposits, a close mate uses 3% and hasn't gone bang, so go with what you feel after initial advice,cheers,Speedy

Tbh im never kind to a fresh built engine, its either a good build or not. id use oil you have been using at 3% and don't labour engine its better to drop a gear and let it work.
One tip i can give is run it up on tick over for ten mins or so with out cowling on, let cool and run up again for ten mins, let it cool and re torque head nuts fit cowling and enjoy

just serviced a GT186 kitted scoot and checked cylinder bore coz of std head being used (now changed to porqupine head) after 2k miles it was well worn!customer was using 3% all the time !is this normal ??

well worn? how have you determined that? did you measure it when it went on new? does it have a lip where the rings run to at the top of the barrel?

spannerman wrote:just serviced a GT186 kitted scoot and checked cylinder bore coz of std head being used (now changed to porqupine head) after 2k miles it was well worn!customer was using 3% all the time !is this normal ??

Please PM or post details of dimensions you have measured and the equipment used. Wear can take place on both bore or piston but this takes many thousands of miles (8-10k and more). By knowing the starting bore and the original piston dimensions you can ascertain the rate of wear in the bore and piston. In many cases changing the piston and rings will restore acceptable clearances without going to the need of re-bores or honing.

It goes without saying, premature wear in GT barrels is not normal. The most common form of this type of wear is from very fine blasting media left in tanks and casings.