Scooterotica

ok then ,glad we are putting all this behind us now and so getting back on topic .
The so called "darrell ports " are good and do work for a TS1 /imola etc ,but I always thought that they were just a poor substitute for proper boyasen ports and cos RBs have the boyasen ports anyways I,ve never tried it with that as i thought that there was no reason to.hence why our sprinter motor hasnt got them ...
also ,
and because i have never tried it myself but do understand how it may work ...has anyone tried the so called "power porting "method out on a reed valve lambrettta ...using full skirted pistons (as in no holes for 360 inlet ) but cut back on the inlet side to say 200 degrees plus ?

No but I found this bit of DIY tuning on a blaster on YouTube,
http://www.youtube.com/watch?v=fdb_8bPE ... ata_player

muppet

well thanks anyways muppett ,but thats not exactly what i,m on about .

On the TS engine we did the work on the engine case was carried out with all the porting work that was done to the cylinder and other modifications, wot part the work to the casings contributed towards the power out put is not conclusive as it wasn't tested with or with out the casing mods.
We've also used this method on piston port engines but again until it's tried with and with out the modifications we don't know if there's a benefit to it or not.

Chris CSPE wrote:On the TS engine we did the work on the engine case was carried out with all the porting work that was done to the cylinder and other modifications, wot part the work to the casings contributed towards the power out put is not conclusive as it wasn't tested with or with out the casing mods.
We've also used this method on piston port engines but again until it's tried with and with out the modifications we don't know if there's a benefit to it or not.

Interesting stuff Chris, thanks.

What i was discussing with Sean, was this: On the casings that we have tried the 'under stud boyesen' ports on and the additional 3rd slim port into the base of the reed area, we still retained the usual piston with windows setup, some were the monza pistons in TS1s and some were MB pistons in TS1s. However after further thinking on this, we thought about trying two further options, one was a full skirted no windows) piston cut to 200 degree inlet (or thereabouts) so the only transfer channels are the 3 transfers (2 main and new 3rd port at back) and no holes in piston, and the second option was the same, but with a slim 'letter box' port in the top of the piston.

I'm thinking there is no need for the usual huge piston skirt windows on these types of tune, as the 3rd port at the back is doing what it needs to to transfer the gasses nand the windows in the piston may actually only server to create unwanted turbulence between the converging gas streams....?

Any thoughts?

The YZ 250 piston has a big half moon cut out and no windows (not sure wot year it is) I've got a water cooled Taffspeed engine in a customers scooter that has that piston in it. The barrel is not on it at the moment, it's having a new head done.
When it comes back I'll have a measure up.

i know i'm going off the subject of porting and stuff,but it's still within the sprinting side of it.

so, just wondering what gearing people are gonna be using,myself i'm using an Li 150 gearbox,but unsure on sprocket set up.

any advice much apreciated.

Chris CSPE wrote:The YZ 250 piston has a big half moon cut out and no windows (not sure wot year it is)

'76 to '79

Yep that's the one Oz, a slot at the top of the piston will do the job of cooling the crown and give some lubrication to the small end, but I wouldn't have thought it would give anything to the performance.

Sean,
Why have 200 degrees when you can have 360?