ESE's works engine tuner

[pete376403]

The heavy piston would crack and drop a piece down into the rotary disc valve.

I think that is what my one did a couple of times, r/v would be shredded - i thought it was happening the other way, the disk breaking and the shrapnel taking out the rest of the engine. The magneto rotor would shear the woodruff key occasionally too. Finally fixed that by lapping the rotor to the crank. But given all its faults I'd still like another one.

[Flettner]

The Bighorn was supposed to be good for 44 HP with the hot kit.
At 6000 about 15HP
7000 it got excited
8500 it was anyones guess as to where it would all end up. Ditch? ambulance? Or win, control was never a strong point of the Kawasaki Bighorn.

[Flettner]

A modern Bighorn

[speedpro]

You can see the resemblance

[Flettner]

You can see the resemblance

Haha I can.
https://youtube.com/shorts/CLn4tsz8M1s?feature=share

[_____]

One question for Jan and Frits:

When I go through the history of the Aprilia Cylinders. I find that in the beginning, with Rotax 128, 129 and even the APC the bottom edge of the boostport is well below the BDC. Roughly 5mm.
Looking into newer cylinders like the APE and APF, I find that the bottom edge sits at about 1.5mm lower than BDC.


Why is the lower edge dropped anyway? And why was it raised in the development process?

Thanks a lot from germany
Chris

[Frits Overmars]

One question for Jan and Frits:
When I go through the history of the Aprilia Cylinders I find that in the beginning, with Rotax 128, 129 and even the APC the bottom edge of the boostport is well below the BDC. Roughly 5mm. Looking into newer cylinders like the APE and APF, I find that the bottom edge sits at about 1.5mm lower than BDC. Why is the lower edge dropped anyway? And why was it raised in the development process?
Thanks a lot from germany
Chris

When I first held a water-cooled 125 cc Rotax cylinder in my hands, in 1977 or 1978, it already had the piston ring gap running over the middle of the C-transfer, which was then 22mm wide. It never gave any problems. The low bottom edge of the C-port ensured that the ring gap did not have to run over it at BDC, which made sense to me.

In the later Aprilia cylinders the C-port width was reduced from 22 mm to 15 mm to allow for wider B-transfers, and Jan noticed that raising the C-port bottom improved flow without causing any ring problems. I don't think a combination of the original 22 mm Rotax port width and the raised Aprilia port bottom was ever tested.

Gestatte mir eine Gegenfrage Chris: warum verwendest Du fünf Unterstriche als Spitznamen? "Chris" ist doch gar nicht so schlecht, oder?
(for anyone who hasn't been punished with German lessons: consider this a great opportunity to practice with Google Translate )

[_____]

Thank you Frits,

that was helpful!

About my nickname: That was what I came up with. No fancy reason behind it :-)

Regards
Chris

When I first held a water-cooled 125 cc Rotax cylinder in my hands, in 1977 or 1978, it already had the piston ring gap running over the middle of the C-transfer, which was then 22mm wide. It never gave any problems. The low bottom edge of the C-port ensured that the ring gap did not have to run over it at BDC, which made sense to me.

In the later Aprilia cylinders the C-port width was reduced from 22 mm to 15 mm to allow for wider B-transfers, and Jan noticed that raising theC- port bottom improved flow without causing any ring problems. I don't think a combination of the original 22 mm Rotax port width and the raised Aprilia port bottom was ever tested.

Gestatte mir eine Gegenfrage Chris: warum verwendest Du fünf Unterstriche als Spitznamen? "Chris" ist doch gar nicht so schlecht, oder?
(for anyone who hasn't been punished with German lessons: consider this a great opportunity to practice with Google Translate )

[wobbly]

I tested lowering the C port floor , thinking there was a good reason to do it , as I had also seen it done by Rotax and various 100cc kart engine manufacturers.
Sadly the flow bench said " nah " and so did the dyno.
My thinking afterwards was that without the last part of the inner wall directing the flow , it simply attached to the vertical piston face , thus screwing up the directional control of the roof trying to keep
the column at 50* or whatever.

[Condyn]

It may be hard to tell in this photo, but the B ports on old 4 port Yamaha piston port snowmobile cylinders drop well below bdc. The B axial angles are roughly 45 degrees. I have never been able to wrap my head around why you would want collision on the piston sending the B column into a turbulent tornado headed for the moon.

[TZ350]

.
Wob did tell me but I can't re locate his post.



Wob or anyone with experience with setting up the EngMod2T temperature file for Methanol. I would love some pointers on what temperatures to plug in.

[wobbly]

160*C bottom of powerband 225*C peak for the pipe , but the Ex Port duct will be much cooler in an Aircooled so that will need dropping as well.
I havnt done an Aircooled on Meth in EngMod so cant show any experience.

[TZ350]

160*C bottom of powerband 225*C peak for the pipe , but the Ex Port duct will be much cooler in an Aircooled so that will need dropping as well.

Thanks Wob. Even though the F81M is air cooled I had used the default water cooled temperature settings in the hope they would be closer to a Meth air cooled engine. I will plug your numbers in and experiment a bit. Thanks again.

[philou]

curious form

[Frits Overmars]

curious form

Well spotted Philou. You might even call it cheating