Piston skirt and other dillema`s

[Fux]

Right... This is a long one...

I was running a TS1 with a 60 x 110 crankshaft.

I got some help from Darrel Taylor on port timings and ended up with a 3mm base packer and a 1.5mm head gasket, effectivley moving the ports down 1mm and this gave me a great pulling scooter with a TMX 30 and bgm clubman.

I moved over to a ADS touring pipe when the clubman fell to bits and it got even better, im also running a cyclone 5 gear box.

Soo...

I have bought a Casa Case and instead of fitting a completely new cylinder kit, Ive got a spare ts1 barel and bgm piston, used but more usable than the this one where the nicasil is on its last legs. I have a national rally in 2 weeks so hope to get it up and running for this and then get help from a grown up on tuning and setting up another kit.


The casa case has a 62 x 110 crank and the case mouth is 3mm taller because they all come with 110 conrods.

(To me, the 3mm higher case is a bit silly because it actualy means less flexibility in moving the cylinder with packers if you opt for a standard stroke crankshaft.)

Anyway, back to the plot. When I fit the TS1 cylinder without a base gasket the cylinder stops dead on the bottom of the exhaust port at bdc, but is too close to popping a ring out of the top for my liking at tdc.

If I fit a 1mm base gasket it looks better but then the piston is 1mm under the exhaust port at bdc. Should I dremmel the exhaust port to match? I do belive that is in the same place it was on my 110 x 60 and ran great.

Dillema nr.2 is that the piston skirt is scarry near the base of the engine at bdc at 0.4mm. Can I trim the skirt 0.6 - 1.0mm for saftey, and will this have any effect on the performance?

I also wonder what the negative outcome would is by using the 62 stroke?

Me being a berk, sold the SIL 200 casing, so this is what I have to work with.

[rosscla]

Trimming the skirt on a piston port motor would alter the inlet timing but as yours is a reed it won't make any difference.