ESE's works engine tuner

[TZ350]

I just love these bikes and the clever work that goes into them.

[F5 Dave]

trailing axle forks. reduces the wheelbase I guess. I'll have to draw a picture to think about how it affect the trail

[Moooools]

trailing axle forks. reduces the wheelbase I guess. I'll have to draw a picture to think about how it affect the trail

Increases mechanical trail.

I suppose that means you can run less caster and maintain your trail. I don't really know why you would want to do this though. The steering angles any bike sees is pretty damn minimal so you aren't going to see any sort of camber through caster.

I do wonder about the purpose of caster at initial tun in though. I suppose because the wheel contact patch moves upwards (relative to COG) on turn in the normal load decreases momentarily on the front tyre. Which could lead to a front end slide. I don't know if the steering rates are great enough to make this a significant change in normal force at the contact patch.

Any thoughts on this. I know it comes up now and again that caster isn't necessary, but is it better to have no caster or perhaps even negative caster (a nightmare to package) so that normal load increases on turn in when the front tyre is doing the most work. All while maintaing adequate trail.

[TZ350]

I have been playing with EngMod simulating the Ball Valve and trying different scenarios.



I have been looking at how the 24mm throttle body will go with the Ball Valve.



And found that the Ball Valve on its own was likely to be better than with the plenum.




Then I had the bright idea to simulate the Ball Valve 24mm throttle body combo with a Boost Bottle.



Red Line is the Ball Valve and 24mm throttle body, Blue line is with a Boost Bottle. It looks like something worth checking out in real life on the dyno.

[TZ350]

Something else to think about, water injection, could it work on a 2-stroke for detonation suppression...



http://www.rbracing-rsr.com/waterinjection.html

That was an interesting read.

Husa, what do you think, should I try puffing some water mist into the bell-mouth at peak torque for detonation suppresion.

[fatbastd]

Impressive graphs. Keen to see a 125 AC bucket with 43hp. I'll be banging on your door!

[TZ350]

Keen to see a 125 AC bucket with 43hp.

Me too, but the simulated graph is crank hp, so you have to drop a bit for rear wheel hp.

31 rear wheel hp, at a guess is more or less 35-36 crank hp.

I have previously made 34-36 crank hp so maybe 40ish is not that impossible.



I wouldn't get to hung up on the hp numbers, the real thing to take notice of, is that EngMod2T is pointing out that a Boost Bottle with the Ball Valve is a worthwhile direction to explore.

[Flettner]

Here is ball valve and EFI at work. Interesting how the variable rotary valve housing needed to be controlled differently to get rid of the unwanted torque dip around 4 to 5 thousand. Thanks to Rob for sorting this out, I thought I knew a bit about rotary valve engines but after this run at ESE under Robs guidance, I am definitely the apprentice.

[TZ350]

The piston skirt was exposing the bottom of the exhaust port at TDC so as an experiment I am screwing and gluing a piece of alloy into the exhaust port floor. With any luck this will let the piston seal the crankcase and I have made the wall a little higher than the piston at BDC.

I remember (hopefully correctly) Frits talking about Jan experimenting with this and that it made more power by reducing short circuiting.

But they had not found the upper limits of how high the wall could be. If I can make the wall high enough it might not be to far fetched to add another transfer port there, after all once exhaust blow down is complete there is little point to the lower 1/3 or so of the exhaust port.

[TZ350]

When I made the triple exhaust port cylinder I was aiming for the maximum blow down STA possible. 200 deg worked well for me on the single exhaust port cylinder so I figured it would be even better with side exhaust port windows.

I wish I had of had the EngMod2T simulation package before I made the triple port cylinder.



EngMod simulation of the 200 deg duration triple exhaust port.



And the shape was pretty much what EngMod said it would be.

The difference in outright power is due to the fact EngMod simulates crank hp, and I can only measure rear wheel hp.

I had also overstated the combustion efficiency of the head I was using and I guess the workmanship is less than what EngMod was expecting too.



The Blue line is the triple exhaust and the Red line is the single exhaust port cylinder, both have 200 deg duration, all other ports and timings are the same.



The Blue line is the triple exhaust with 188 deg duration and the Red, the single at 200.



I guess I may need to also think about attaching something to the exhaust port roof to change the exhaust timing from opening at 80 deg ATDC to 86.

When I have proved the cylinder layout on the dyno I will make another one that incorporates all the good bits.

[RomeuPT]

Here, Have my like TZ. Great Project, Great Dedication.

Waiting for the results of having that piece of alloy in the exhaust floor

[fatbastd]

me too. Stock 1970's TZ exhaust ports usually have a little 'ramp' too. It's subtle and many people grind it out...and make less power. Years ago, a mate in the Uk sold a TZ cylinder to someone drag racing an RD engine, quite successfully. The buyer noted that the ramp had been removed - he wasn't bothered, saying that he'd soon put it back in (and a bit more)..

[TZ350]

me too. Stock 1970's TZ exhaust ports usually have a little 'ramp' too. It's subtle and many people grind it out...and make less power....

Yep ... been there done that ....

Here, Have my like TZ. Great Project, Great Dedication. Waiting for the results of having that piece of alloy in the exhaust floor

... noted that the ramp had been removed - he wasn't bothered, saying that he'd soon put it back in (and a bit more)..

Thanks guys, hopefully get it sorted for the weekend.

[Flettner]

Yes, TZ I too am considering placing a small transfer port in that front area below the exhaust port. In the new piece of " realestate" opened up by raising the bottom of the exhaust port. First need to confirm how high this " dam " can be? This could be very useful for helping to cool the front exhaust edge of the piston each cycle, the most dangerous area.

[F5 Dave]

ok I understand the gluing bit, (although devcon in direct contact blows out of an ex, maybe the ally will shield that). . . -but how the heck do you 'screw' it in?