ESE's works engine tuner

[TZ350]

Spent a happy afternoon at Flettner's place digging through his surplus Kawasaki BigHorn parts. He found a stack of useful stuff and donated them to the cause. There are cases and cylinders plus cylinders from Yamaha and Suzuki. Gear box parts and side covers, plenty to sort through. And a frame modified to move the Kawasaki engine 50mm further forward to put more weight on the front wheel. Many thanks Flettner.....

The plan is to check through as many likely cylinders as we can and select the one with the best outer transfer duct shape. Then sleeve it back to 250cc. And with a thick alloy sleeve we should be able to cut a triple exhaust port and the inner sweeping transfer shape into it.

The pre 72 Japanes pre 76 European 250cc light weight class I am looking at riding in has mostly Yamaha DS7's and Benelli 2C 250 twins. Typically they make mid 30's rear wheel horse power and the top ones, low 40's.

With everything that has been written on here by those that know and the use of Engmod to develop a plan. If I can't get mid 40's RWHP out of the much lighter rotary valve Kawasaki I should be ashamed of myself......

[adegnes]

I had the same plan, though not for the same reason.
I was working on 6.5 cc MB40-engines for F3D model airplanes. The fuel tank position in the fuselage of these little planes is critical as they pull a lot of g's in corners (we don't know how many g's exactly because the g-sensor's maximum is 'only' 36 g). When the fuel level drops, the mixture strength changes; not nice.
My plan was to replace the cruel fuel system (fuel in a bladder with exhaust pipe pressure squeezing the bladder from the outside) with a pump injection. It had to be constant flow because I could not find injectors capable of delivering the required tiny amounts of fuel to a 36,000 rpm engine.
I found suitable pumps here: http://shopping.netsuite.com/app/site/site.nl?alias=flightworks . These pumps are designed for model jet turbines but the snag is that the DC pump motors cannot run slowly enough for a small piston engine; the pump would drown the engine at the first start attempt.
Stepper motors were considered but the problem with those would be that when rapid pump acceleration is required, the stepper motor may miss steps and the engine will lean out without any feedback other than a complete cut-out because of a molten glow plug.
Pulse width modulation for the original DC pump motor was considered next, but then other things took priority so the idea never got finished.

I like this approach a lot!

[peewee]

Attachment 343503 Attachment 343504 Attachment 343505

Barn Find, or re discovery by the original builder. A 1972 Kawasaki F9 350cc BigHorn racer. https://www.cycleworld.com/custom-built-race-winner/

I am not looking to build a monocoque but I am looking to build a pre 72 racer using a Kawasaki 350/250 rotary valve motor. I want to race my friends who ride pre 76 Beneli 250 two strokes and pre 72 Yamaha twins. The plan is to get a rotary valve BigHorn 350 and sleeve the cylinder back to 250. Sleeving the big cylinder back should allow room for some modern porting trickery like axillary side exhaust ports and staggered large radius sweeping transfer ducts. A decent combustion chamber shape and modern pipe design with digital ignition. Running methanol which is allowed in pre 72 here. It should hopefully keep things cool enough so I don't have thermal problems with the plated alloy sleeve.

Anyway, if you can help. I am looking for Kawasaki rotary valve 350cc BigHorn F9 or F5 and/or 250cc Bison F8 engine/gear box parts and any info on the early BigHorn 350cc racers. If we can do a deal and the items are packed and addressed I can arrange collection from pretty much anywhere in the world.

seems heres a f4. never heard of it before
https://classifieds.ksl.com/listing/57946754

120 superlube ? never heard of it
https://classifieds.ksl.com/listing/57932093

f7. sorry never heard of it
https://classifieds.ksl.com/listing/57863583

bushwacker
https://classifieds.ksl.com/listing/57863543

[SwePatrick]

Here you can see my problem with clearance between tire and pipe.
i might just put a smaller tire on to gain some clearance as i also need to lower the rear some.



Don´t mind the mess,,, professor at work!

[wobbly]

Move the pipe center-line to one side up near the belly to clear the tire.
Same as a twin pipe out the back setup.

[SwePatrick]

I could do that, but i want it to be easy to build new pipes, easiest pipes must be a straight one
If routing it a bit to the side i will get into new problems.

I can lift the pipe about 20mm.
and a smaller rear tire would also give me about 10-15mm
Then i think i´m home free.
I havent made the pipe oval yet

[wobbly]

There is already a bend in the header.
Put a bend at the end of the header/start of diffuser join , then one at the end of the diffuser/start of the mid section.
No extra cuts or welds - easy.
Oval changes the area and thus the pipes efficiency - bad idea.

[TZ350]

Mockup of my new engine in the frame.
Green is small carb with reed intake, blue is big 24/7 intake with a slide valve for opening at WOT.
The case is pretty much ready for machining.



Constant rpm/load/throttle opening(WOT, no throttle)

Questions:
- Anything wrong with mounting injectors where I've marked in the drawing?

- Been thinking I should use two and have one open as the other closes to minimize "gaps" in delivery - necessary? One would be preferable, less parts.

Does one 900cc/two 450cc injectors sound sensible? (two 900cc if I want them to alternate on/off)

I would pick two 900cc injectors fired alternately and overlapping each other as required when time gets to short for one injector to open-FireFuel-close, move the open-close part and some fueling if needs be to the alternate cycle.

I think for what you are trying to do, EFI will serve you well.

Timing of the injector closing point seems to make a difference to performance too. I aim for injector closing at BDC where the pipe is sucking its hardest. Flettner found aiming for injector closing at transfer closing worked best for him.



This is Flettners two injectors. You can just see the injector nozzles at the back of the "C" port duct of the Kawasaki BigHorn crankcase. They fire horizontally across and above the flywheels. This worked well and looks a bit like the arrangement you have in mind.



I had a lot of success by firing directly across the bottom of the transfers.

But this was not always possible and I tried a lot of different configurations like firing 4 stroke style with the wind going down the inlet tract, and that was the worst.

Nearly anything with two strokes and fuel injection behaves totally different to four strokes. The message is, to avoid disappointment, don't blindly copy any of the methods used with 4T EFI.



"B" port injection against the wind seems to be the best practical arrangement and currently gives very good results.

Anyway for what its worth, that is my take on it.

[Flettner]

You saw it here on Kiwi Biker first, mk2 TPI.
This arrangement allows for better control and better homogenization. B port injectors first at low speed, then A and B port injectors once up on the pipe. B port TPI will supply fuel to the A ports at longer injector on times but not so controlled, not like this.
Anyway if I were you I'd inject like this.

[husaberg]

You saw it here on Kiwi Biker first, mk2 TPI.
This arrangement allows for better control and better homogenization. B port injectors first at low speed, then A and B port injectors once up on the pipe. B port TPI will supply fuel to the A ports at longer injector on times but not so controlled, not like this.
Anyway if I were you I'd inject like this.

Odd est ignition set up there Neil......

[TZ350]

.
Kawasaki F81M Post Classic Racer Build.

Now that we have some parts to play with, the ideas can flow.



The first step is to improve the transfers. The Suzuki has a much better looking duct shape than the Kawasaki.



If I fitted the piston port Suzuki cylinder to the rotary valve Kawasaki. I could have two inlets and arrange one of them as a 24/7 when its up on the pipe. Open all hours, it's kinda crazy, but a very tempting idea..... . There have been racing single cylinder twin carburetor specials made before.

I am not sure if fitting a Suzuki cylinder to a Kawasaki will be regarded as an after market conversion or a tuning modification. Back in the day I was running Yamaha cylinders on my TR250 Suzuki so mix and match has certainly been done before.

These are the class rules:-

[adegnes]

I would pick two 900cc injectors fired alternately and overlapping each other as required when time gets to short for one injector to open-FireFuel-close, move the open-close part and some fueling if needs be to the alternate cycle.

I think for what you are trying to do, EFI will serve you well.

Timing of the injector closing point seems to make a difference to performance too. I aim for injector closing at BDC where the pipe is sucking its hardest. Flettner found aiming for injector closing at transfer closing worked best for him.



This is Flettners two injectors. You can just see the injector nozzles at the back of the "C" port duct of the Kawasaki BigHorn crankcase. They fire horizontally across and above the flywheels. This worked well and looks a bit like the arrangement you have in mind.



I had a lot of success by firing directly across the bottom of the transfers.

But this was not always possible and I tried a lot of different configurations like firing 4 stroke style with the wind going down the inlet tract, and that was the worst.

Nearly anything with two strokes and fuel injection behaves totally different to four strokes. The message is, to avoid disappointment, don't blindly copy any of the methods used with 4T EFI.



"B" port injection against the wind seems to be the best practical arrangement and currently gives very good results.

Anyway for what its worth, that is my take on it.

You saw it here on Kiwi Biker first, mk2 TPI.
This arrangement allows for better control and better homogenization. B port injectors first at low speed, then A and B port injectors once up on the pipe. B port TPI will supply fuel to the A ports at longer injector on times but not so controlled, not like this.
Anyway if I were you I'd inject like this.

Thanks a bunch to both of you!

The more I think about this, the more I lean towards setting it up like a wet nitrous system without nitrous.
Just one "fogger nozzle", a solenoid, and a pump.
Controlled by varying return flow to the tank.

[Frits Overmars]

You saw it here on Kiwi Biker first, mk2 TPI.This arrangement allows for better control and better homogenization. B port injectors first at low speed, then A and B port injectors once up on the pipe.

I love it Neil .

Odd est ignition set up there Neil......

Never seen a high-tension cooler before Husa? Oh well, you're probably too young .

[andreas]

.
Kawasaki F81M Post Classic Racer Build.

Now that we have some parts to play with, the ideas can flow.



The first step is to improve the transfers. The Suzuki has a much better looking duct shape than the Kawasaki.



If I fitted the piston port Suzuki cylinder to the rotary valve Kawasaki. I could have two inlets and arrange one of them as a 24/7 when its up on the pipe. Open all hours, it's kinda crazy, but a very tempting idea..... . There have been racing single cylinder twin carburetor specials made before.

I am not sure if fitting a Suzuki cylinder to a Kawasaki will be regarded as an after market conversion or a tuning modification. Back in the day I was running Yamaha cylinders on my TR250 Suzuki so mix and match has certainly been done before.

These are the class rules:-

Somewhere I read reed valves not permitted, that would make the 24/7 less atractive. A guess is that a well flowing c-port is worth more than superior induction, at least that is probably why Suzuki abandoned their otherwise excellent power reed system. Then again surely there is a solution...

[jbiplane]

Just curious if it is a good idea to try make engine with very exhaust small duration, but very wide exhaust port to minimize exhaust system size and weight. Anyone tryed to make it with volume about 125cc? Will engmod preduct behaviour of this?