Lambretta Boost Port & Cylinder Scavenging

[Rich_T]

I'd expect smoothness will be down to crank balance/piston/rod mass.

None of the crank manufacturers/suppliers list a piston mass table so it is pretty much a given that the engine will feel lumpy unless, buy chance or a combination of trial and error, you hit a sweet spot.

But yes, the few TS225's I've seen have a lower boost port which would support that (actually the stock port arrangements are a bit currious by todays standards). It also means material off to adjust the angle and raise the timing or both. Which, unless you want a boost with low timing and large entry angle, will always necessitate the barrel being modified.

As Tony (I think) mentioned earlier, the TS was designed for it's time, the fact that it still really has no solid successor is a pretty much an astonishing tribute to it's tooling and manufacturing quality even though the most street engines end up having the transfer & boost timings matched & lowered.

[RICSPEED]

one thing that terry wanted and is now a feature on the rb was the exhaust exit angle ... again i think not done at the time for ease of converting the flange on existing pipes .. how does exit angle effect things ?

[sean brady scooters]

For sure Ric. And thats what I said. This takes us back to the pipe design. Thats the only thing has changed that will affect really... So... someone says "thats all wrong" well... they maybe right... today.... but when it was designed, maybe not at all.

not forgetting that the fuel we use now has also changed since the ts1 kit was developed ..and hence the compression ratios that we now use and timing to suit .

[Wayne Miller]

Not forgetting that the fuel we use now has also changed since the ts1 kit was developed ..and hence the compression ratios that we now use and timing to suit .

Damn it Sean, just when I start to think that I'm on the edge of understanding you throw fuel v's port timing in

I kinda get the compression ratio thing and understand that this may have to be altered but why would a modern fuel alter port timings? why and what has to be altered?

Im off to hit myself on the head with a hammer

[Wayne Miller]

i have a feeling he's talking about ignition timing tbh

Ha ha ha, pmsl thank god for that I thought my head was gonna fookin pop off !!!!!

Well at least Ive just found some good info on the tinterweb about compression ratios and MSV's

[Chris CSPE]

Wot about the angle of the piston crown and the effect it has on every degrees of opening of the boost port and not just a straight flow into the cylinder.

[sean brady scooters]

lol,now we are getting into the use of flat top pistons like KTM etc use

[Chris CSPE]

lol,now we are getting into the use of flat top pistons like KTM etc use

Really!! That's not wot I've used.

[Chris CSPE]

Wot benefit is gained by having the boost port open before or at the same time as the main and secondary transfer ports??

[Muppet]

Wot benefit is gained by having the boost port open before or at the same time as the main and secondary transfer ports??

Agghh thats not fair you can't leave me hanging like a loose tooth go on gizz a clue
muppet,