ESE's works engine tuner

[F5 Dave]

OK Sketchy, time to move into mass production.

[wobbly]

I originally built the BSL crank with integral pins ( it made the engine 17mm narrower - big deal )
Sadly no matter how it was done, with big radi and shot pienning etc the bastard pins kept cracking.
This was due to some form of harmonic or torsional twist from firing 2 of the 3 cylinders together.
In the end I tried a crank with the same dimensions ie only 12mm of press fit on the side where the pin originally was one piece.
We made a jig that kept the pin dead square in the crank hole, and tigged it right around the outside face.
Never had a crank issue after that.

So I would suggest spark eroding new pin holes, in the integral side,and welding in new pins may in fact work.
But from memory the Honda and the RGV/RS250 may be even thinner than 12mm.

One thing to be aware of - the original crank had the pin holes on the non integral side moved inward 0.008mm,as when the pin was pressed in
the wheel material would bulge outward,changing the stroke length by that amount.
Thats not an issue if both sides are pressed in, and both wheels are identical.

In this case it might take a couple of cranks to get the new hole position dead on such that the thing will straighten correctly due to the thin press width.
Having the stroke lengths not matching is easy to detect, with 2 dial gauges on each end of the same axle, both will rise and fall together - impossible to correct.

[Muciek]

Measuring that 0,008 mm would be pretty hard to do most normal measuring gauges go to 0,01mm , unless You are talking inches then 0,008 it's 0,02mm but would that make a big difference? Guys here used to be doing thing like this on RZ cranks since it was cheaper than buying new one from overseas and they were not that available like they are now.

[wobbly]

You are not measuring it at all, you would be programming a CNC spark eroding machine to bore the pin hole at a reduced the stroke of 0.008mm.
But if the wheels are thinner than 12mm as the BSL ones were, then 0.01 would probably be closer.
And yes 0.02mm runout in a crank is nowhere near "straight ", it would destroy the main bearing and or fret the cases due to the wobble in no time.
This is why I have probably 10 RZ cases that are junk, because the main bearing journal faces are worn oval, from crank rebuilders who didnt know what they were doing.

[Muciek]

I got You wrong (lost in translation)I thought that stroke would change that 0,008mm and You would have one side with other stroke than other.
Wouldn't it be better to grind the hole instead of EDM'ing it? You would probably get "rounder" hole and better surface finish , anyway machining with tolerances under 0,01 is trick stuff.
offopic what was the acceptable run out for those twin's cranks , (honda, yam, and suzuki) , not talking about racing but normal use , did factory always was getting it at 0 and in service manuals was stated like this? Many bikes have limit at 0,02mm and it is normal.

[jonny quest]

Not saying you're wrong Wobbly, but even at ,04mm shouldn't fret or damage cases.

Crank rebuilding is an art, I do a lot of singles, and it's not uncommon to see them come out with 5 hours run time at ,15mm runout.

You put a hairdryer to a crank with ,02mm runout and it will move almost twice that

[jonny quest]

Edm is probably more precise than grinding. Edm was the way I was going to put the pin holes in the crank.

Is there a rule of thumb for press fitment of pins?

There's a place making Kr1 Inner webs with the pin machined on. From the pictures they look super close. I wonder if they would fit, or fit with some slight mods

[wobbly]

The problem with the twin is that if you are prepared to accept 0.02mm or 0.03 runout like Yamaha says , then this can be at both ends.
It can also easily be on opposite sides, so in effect you then have 0.06 runout across the outer mains - this is why the tunnels are wreaked, being oval or with no crush
in most every old RD/TZ/RZ case I measure these days.

Edit - yes I agree about cranks moving after being run, but in my opinion this is due to having excessive amounts of hammering to get them " true ".
The metal in close contact is very springy, and I have found that if the wheels are held dead in line in a die set so that there is no need to hammer the shit out of them
they dont move at all.
If hammered they will always spring back a little in the direction they came from.

[TZ350]

Rob, is it time to do a total fundamental reality check? Could it mean taking off all the injectors and chuck on a carb? Means getting rid of the neat throttle valve, but maybe you need to understand if it's some form of injector peculiarity or some unique characteristic of the engine as it has been built.

Have been hoping to avoid reality, this engine has run very well in the past with a carb. But its looking like you are right, it is shaping up to be something about the injectors. Maybe they need to be angled differently.

If the main problem with the carb setup was the fuel and oil that eventually may not reach the engine, maybe, is possible to build the chamber only upside of the inlet pipe, so the gravity kept fuel and oil always on the inlet. May be quite a bit of work and possibly more work/benefit than with the EFI setup, though...

Yes, good idea, we had thought of it but like you say, hard to do on the rotary valve engine but could be very possible to arrange the plenum in such a way it drains into the inlet on a reed or piston porter.

Rob - I'd try the low speed injector on the downstream side of the throttle valve - and aimed at a port wall. From what i've read on 4T injection in low airspeed conditions, you get better results if the injector stream can be made to splatter - for want of a better word...

Good idea, thanks, I might need to look at how I could do that.



Initially it looked like it was anything less than 20% throttle (left cursor) was the problem. But after a bit of time studying the recorded data it is beginning to look more complex.

As the rpm picks up (top line) you can see the rough running smooths out (right cursor) as the difference between injector on time (green line) and the total injector on time available (red line) reduces to 30%. 30% is about the amount of time the transfers are open.

To my surprise the engine runs rat shit when the injector on time is much less than the transfer open time and it gets better when the injector is on for longer than the transfers are open and best when the injector is on the whole time. Actually I suppose that should not be such a surprise because a carb is on for the whole time too, and they run Ok.

After looking at quite a lot of data it looks like the engine runs rough when the injector on time is less than the total transfer open time. The engine runs better the longer the injector is turned on. And of course anything less than 20% throttle there is not much injector on time and the thing runs like a pig.

It must have to do with fuel homogenization. A carb adds fuel to all of the air that passes through it but with an injector, under 30% on time I must be getting big patches of air with no fuel in it. And when the injector has to be on for much longer the air is getting a more consistent mix that is more like that delivered by a carb.

On over rev with the throttle shut there is very little injector on time. So because I can't fire the injector for the full transfer open time. I guess the trick is to find a way to thoroughly homogenize the air fuel mix or at least time the injection point to coincide with the air that will eventually be trapped in the cylinder.



Up till now I have had the big injectors on either side with the slow speed injector in the middle. Maybe worth my while reversing that and trying two small slow speed injectors either side with a really big power injector in the middle. If that results in better mixing and works well then as an extra up side I would be also getting lots of underside piston cooling from the power injector.


The big question is, is how to get a homogeneous mixture of the correct air fuel ratio in the cylinder when the injector is only on for a much shorter time than the transfer window is open.

[dark art]

Up till now I have had the big injectors on either side with the slow speed injector in the middle. Maybe worth my while reversing that and trying two small slow speed injectors either side with a really big power injector in the middle. If that results in better mixing and works well then as an extra up side I would be also getting lots of underside piston cooling from the power injector.


The big question is, is how to get a homogeneous mixture of the correct air fuel ratio in the cylinder when the injector is only on for a much shorter time than the transfer window is open.

That makes a lot of sense, and it seems the middle injector is spraying directly on the boost port. I guess the obvious step, is to move the injectors away from crankcase so there is more time to mix things up...

[Grumph]

Fuel homogenisation is best achieved in a turbulent stream. You get this in a carb when the air passes the slide. Is the ball valve throttle too streamlined ?
Traditionally most throttle bodies for injection are either butterlies or a flat plate sliding.
Quick test would be to put a carb body on it and use the slide as the air throttle, injecting close to the downstream side of the slide...

[TZ350]

Thanks Husaburg for the Cagiva story, its the same problem I am having.

Mr Bigglesworth's Dyno runs.



.... rich areas ....

Initially I thought these were rich areas and to get it running nicely all I had to do was carefully adjust the corresponding parts of the map.

But I now think the problem is with the injection on time being much less than the transfer port window open time and consequently poor fuel homogenisation.

Fuel homogenisation is best achieved in a turbulent stream. You get this in a carb when the air passes the slide. Is the ball valve throttle too streamlined ?
Traditionally most throttle bodies for injection are either butterflies or a flat plate sliding.
Quick test would be to put a carb body on it and use the slide as the air throttle, injecting close to the downstream side of the slide...

I have a butterfly type throttle body, it will break my heart if I have to discard that ball valve throttle. But I guess you are right, and in the interests of science I will have to try it.

[TZ350]

That makes a lot of sense, and it seems the middle injector is spraying directly on the boost port. I guess the obvious step, is to move the injectors away from crankcase so there is more time to mix things up...

There is no wall on the cylinder side of the boost port and the middle injector sprays through a slot in the piston in the hope of cooling the underside of the piston crown. If I can I would like to retain that feature and put the big injector there. Small injector in the throttle body and big injector in the boost port.

[Haufen]

The big question is, is how to get a homogeneous mixture of the correct air fuel ratio in the cylinder when the injector is only on for a much shorter time than the transfer window is open.

Did you try varying the injection timing, eg starting just when the transfers closed?

Otherwise, a smaller low speed injector, or a lower fuel pressure should allow for a longer injection time.

[TZ350]

Did you try varying the injection timing, eg starting just when the transfers closed? Otherwise, a smaller low speed injector, or a lower fuel pressure should allow for a longer injection time.

Yes...

In the Ecotrons EFI software there is a way of mapping (seperate to the fuel map) the injection end point.



As best as I can tell, in the manual the picture is a 4T map and the Injection end point is so many degrees before TDC on the next firing stroke.

For me it would be something like 120 degrees if I wanted to finish the injection squirt as the transfers close.

I have tried 90 - 180 - 120 - 270 and 360 before TDC, and 180 ( or BDC) worked the best.