ESE's works engine tuner

[lodgernz]

Cool video Chris. RS125 frame I assume, but what's the engine?

[timg]

Cool video Chris. RS125 frame I assume, but what's the engine?

NF4 & Derbi 50 I believe.

[husaberg]

Cool video Chris. RS125 frame I assume, but what's the engine?

Ex Honda Dave Aprilia RS50 engine isn't it?

[F5 Dave]

Derbi

Thanks Chris, I watched it all. Miss that bike.

[katinas]

Katinas, I find your posts about new flow paths and so on very interesting. Hopefully you will be able to do some real testing as the snow goes away..? About the "c-port powervalve", your thought is that the c-port shall be blocket up until about mid-range?

Yes Norman, would be interesting how engine respond with blocked C, until higher rpm, before pipe goes on and this is would be not difficult to try. If torque at mid revs rise up, then possible connect adjustable C valve to Ex PV through linkages.

Now revert my engine to rygerised shape, but very different from last year, and maybe fire it in two weeks time. So I am not sure which type try first on the road, when snow goes away. If all pieces is in place, then would be possible revert engine, from one type to other, in one day.

[katinas]

Thanks for that, the boysens are not to bad on this cylinder. Interesting you found a gain with no piston holes

First time, it was four or five years ago, when I made two 7mm holes, on std. NS 400 piston with two big holes on lower skirt side, directed upwards just below second ring in arrange with two small C ports. On the road, some engine sharpness disappeared from 6000-8000 rpm. And then I try so many different combinations, add photo with tested pistons, from last year post. But again, piston without holes work just with Boyesens, without them, maybe arrange of pistons would be in opposite way.
Even last year, when tested piston with pockets, I drill two 8mm holes (add photo),to communicate space over the small end and side piston pockets. And again, some sharpness gone. Then put plugs with 9 mm tread and power restored. Now I am scared about additional holes on pistons skirts.

Add photo of cylinders with the biggest Boyesens I ever see. Don't know engine performance capability with this cylinders, but if for some reasons reed cylinder continued exists, this type looks reliable for pistons and promising for power.

[wobbly]

What are those cylinders ?

[ceci]

Solo muestro , no comento nada,

[ken seeber]

Flashy vid, but something of interest. Look at the chamber shape in the stills.

https://snowmobiles.polaris.com/en-u...atriot-engine/

[SwePatrick]

Don't know engine performance capability with this cylinders, but if for some reasons reed cylinder continued exists, this type looks reliable for pistons and promising for power.

Looks like snowmobilecylinders(Rotax)?

If around 800cc they often produce around 130-140hp OEM, and a whole lot more in tuned versions, up against 180hp.

[katinas]

What are those cylinders ?

Yes, this cylinder block from SKI-DOO-ROTAX-800. Saved this photos from ebay.

[Muhr]

First time, it was four or five years ago, when I made two 7mm holes, on std. NS 400 piston with two big holes on lower skirt side, directed upwards just below second ring in arrange with two small C ports. On the road, some engine sharpness disappeared from 6000-8000 rpm. And then I try so many different combinations, add photo with tested pistons, from last year post. But again, piston without holes work just with Boyesens, without them, maybe arrange of pistons would be in opposite way.
Even last year, when tested piston with pockets, I drill two 8mm holes (add photo),to communicate space over the small end and side piston pockets. And again, some sharpness gone. Then put plugs with 9 mm tread and power restored. Now I am scared about additional holes on pistons skirts.

Add photo of cylinders with the biggest Boyesens I ever see. Don't know engine performance capability with this cylinders, but if for some reasons reed cylinder continued exists, this type looks reliable for pistons and promising for power.

Rotax max cylinders doesn't use piston windows either.

[SwePatrick]

I have seen good results with just a small window as high as possible underneeth the pistonring, aimed upwards into boost runner together with huge boyesens.
The port is about 6mm high and 18mm wide, aimed about 50-55 degree upwards.

But this might be because cylinder has the C-port wide open into reedhouse.
I think it helps push the mixture upwards into the short runner there is.

And if having holes lower down in piston might disturb reedpetals.
And maybe even blow away mixture that should have gone upwards into c-port, due to ejector.

A bonus is that you get some cooling effect underneeth the pistoncrown.

[peewee]

Yes, this cylinder block from SKI-DOO-ROTAX-800. Saved this photos from ebay.

that large boyesen port must make the B passage extremely short. is that no concearn ?

[katinas]

I have seen good results with just a small window as high as possible underneeth the pistonring, aimed upwards into boost runner together with huge boyesens.
The port is about 6mm high and 18mm wide, aimed about 50-55 degree upwards.

But this might be because cylinder has the C-port wide open into reedhouse.
I think it helps push the mixture upwards into the short runner there is.

And if having holes lower down in piston might disturb reedpetals.
And maybe even blow away mixture that should have gone upwards into c-port, due to ejector.

A bonus is that you get some cooling effect underneeth the pistoncrown.

Thanks, and this is why so interesting to have a deal with 2 stroke engines.

Other things, like powervalve or reed house petals seat angle, can make a difference. Honda NS cylinders is without powervalve, and some torque drop always persists around 7000 rpm, but pistons without holes eliminate this, its like with powervalve.
On the other hand, with powervalve cylinders maybe not so big difference and holes can help add some power at high revs.