ESE's works engine tuner

[TZ350]

Cheers, will open up the B ports some more tomorrow. What sort of size do you drill the boost port? And do you have to fill the hole in the piston when opening up the casing? Have been trying to keep the angles of the ports close to standard but will check them tomorrow again. Also going to smooth off the intake part of the casing all the way to the air box, so many weird shapes going on in there

Yes, the whole inlet system can use a tidy up.



Getting the "B" ports as wide as possible. Original "B" on the right, widened "B" port on the left.



I can't remember the drill size but I think it was about the same size as the width of the original C port slot. I know you can't, but we used copper to shift heat away from high thermal load areas of the cylinder.

We did all sorts of things with the hole in the piston. Sometimes used pistons with no hole other times made the hole area much larger and angled to help flow cooling air/fuel up through the piston to cool the underside of the piston crown. Cooling is always a good thing.



You can go quite extreme with the piston hole. Maybe a drilled and ported "C" boost port, big slot piston and no case porting so that all the "C" port mixture flows through the piston may be the way to go.



We got to 31 RWHP on our air cooled GP125's but the inability of the cooling system to get rid of 30+ kW of waste heat eventually defeated us. 22 RWHP seemed quite reliable even without all the copper.

[TZ350]

With a bit of porting gymnastics it is possible to add side exhaust ports to a GP125 cylinder. Probably possible on a 100 too.

On this cylinder. As an experiment, the main exhaust port floor was built up by screwing and gluing a alloy plate in the port floor.

Although they each added something they were so much work we did not bother to do it on our Team's race cylinders and we had hit the thermal wall anyway.

Might be worth trying on a 100 though.

[Roflhat]

Got more done today, pretty happy with the barrel the way it is now, cut the boost port in and opened up the B transfers more. Should I cut the liner behind the boost port too? Seeing some of your photos have a groove cut
Started on the casings too, a bit more to do had add some liquid metal.
Frame is all powder coated now, was getting a bit rusty with the salty air we have here

[philou]

Jan Thiel Book

[TZ350]

... pretty happy with the barrel the way it is now, cut the boost port in and opened up the B transfers more. Should I cut the liner behind the boost port too?

Your work is looking good.



If you port the cases here for the boost port you will break through into the gear box breather cavity inside. You may be able to avoid splitting the cases.

I would now days be tempted to cut the liner in the boost port to make it one big slot with 55 deg's at the top to direct the flow up the back of the cylinder. Put a big slot in the piston and not port the cases. Its worth thinking about anyway.

[jamathi]

Jan Thiel Book

For the moment in Italian.
Later Spanish, Dutch and English versions will follow,

[diesel pig]

For the moment in Italian.
Later Spanish, Dutch and English versions will follow,

That looks great Jan. I will get a English copy when it is really to go as my Dutch is no good.

[Roflhat]

Cheers

So you’d cut the liner away altogether from the boost port? And presumably smooth the open end where I drilled the C port so it’s closed again?


Would you make the hole in the piston the same width as the C port?

[TZ350]

Cheers

So you’d cut the liner away altogether from the boost port? And presumably smooth the open end where I drilled the C port so it’s closed again?


Would you make the hole in the piston the same width as the C port?

Yes match the piston to the port and elongate the hole a bit. Do you think the cylinder spigot is strong enough to cut the slot right through? You are leading the way here, it might work. All you need is the hole in the piston to line up with the slot from transfer port opening to BDC.



This is what ours look like but we also heavily ported the case. You may be able to slot the cylinder all or most of the way and only lightly shape the edge of the case. Certainly worth looking to see what can be done here easily.



This is a standard RGV250 cylinder. 56mm bore 50mm stroke, the same as the GP125. Because of the different thrust loading's front to rear the rear of the cylinder spigot does not have to come all the way down. The front of the RGV bore measured 110mm from top to bottom and the rear 95mm. You could copy that if it helps.

[Roflhat]

Will have to put the barrel on and get some measurements to see where the piston hole will need to be, I like the idea of the extra cooling especially for Bonneville. If I don’t have to cut the slot all the way to the base of the cylinder that would help the strength but maybe worse for flow?
First time really doing porting it’s hurting my head a bit thinking about it now.

Merry Christmas!

[Peter1962]

For the moment in Italian.
Later Spanish, Dutch and English versions will follow,

That is great news, Jan.

[Niels Abildgaard]

For the moment in Italian.
Later Spanish, Dutch and English versions will follow,

Where can it be ordered in italian?

I can make some sense from reading italian.

[philou]

Where can it be ordered in italian?

https://www.editricelamandragora.it/...875866723.html

[Niels Abildgaard]

https://www.editricelamandragora.it/...875866723.html

I have tried.Thank You.They only post to Italy .

[Hoebra]

Can anybody translate into english whats written to the books content? "Just" more historical, or also technical 2stroke aspects?