ESE's works engine tuner

[ApolloMotoMoto]

Connected from home for the first time since mid November!

Hoooray! Now its a "proper" homecoming

[TZ350]

Was pretty happy with the way the Suzuki RG50 rotary valve conversion is going.

The moth holes into the crankcase will get sealed up with some J-B Weld.



Everything was a neet fit.



RG50, rotary valve and 26mm carburettor.

[diesel pig]

I take it those are GP100/125 rotary valve parts? How are you going to drive the rotary valve between the carrier and the crankshaft? Are you going the sacrifice the taper part of a RG50 stator flywheel?

[TZ350]

I take it those are GP100/125 rotary valve parts? How are you going to drive the rotary valve between the carrier and the crankshaft? Are you going the sacrifice the taper part of a RG50 stator flywheel?

RG50 crankcase

Yes, Suzuki GP100/125 rotary valve parts.

AM6

This is an AM6 crank but the approach is the same with a RG50 one.

The long stroke AM6 crank and 95mm rod paired with an oversized cylinder can give you a 100 plus water cooled CC's in a light weight engine.

20mm sleeve and step on the trigger to support the RV hub.

The old flywheel hub is turned down to form the ignition trigger.

The trigger does not have to be pulled up tight on the taper.

The alloy cup pulls up against the end of the crank and just gently presses the trigger onto its taper so that it all comes apart again easily.

The direction of crank rotation naturally tightens the nut holding the trigger.

The crush from the "O" ring on the trigger is all that is needed to clamp the RV hub.

5mm pin in the crank to drive the RV hub.

AM6

The RG50 crank is a bit longer than the AM6 so needs the thread cut off the RG and a 6mm thread tapped in to hold the trigger in place.

The RG crankcases without the crankcase reed and long rod leves an enormous cavity. No idea how much but there must be a lot more relative crankcase volume Than the Aprilia RSA125 had.

I figure, so long as a bit of mixture makes it upstairs to light the fire and get the pipe working, pipe resonance will take it from there. The greater the crankcase volume the more mixture the pipe can suck upstairs to the cylinder. Only works on RV engines, reed engines need some crankcase compression pressure to close the reeds after the suction stroke.



To fit the RG50 crankcase in a NF4 frame we mill 30mm of the drive side mount after bogging up the inside with a bit of Knead-It. The full RV conversion takes about four of the big tubes.

Team ESE still have not made an 50cc engine that is good as the better Dutch efforts, but we live in hope.

[wobbly]

TeeZee, you are making some pretty wild assumptions, for no reason, as EngMod quickly tells you if an idea is sound or not.
You say you have more relative case volume than the Aprilia that had about a 1.23 ratio, and im sure with 100 people working in R&D that if a bigger case was better, it would have been tested and subsequently used in GP's
- why are you assuming bigger, is a better, if its never been tested in a controlled back to back.
But the sim will tell you immediately if bigger is better, and what the best timing's are for that setup.

And reed engines don't need " a smaller case volume to give some compression to close the reeds ", they need a smaller volume as going incrementally bigger requires thinner reeds to match the Helmholtz
of the case, and if its not done, this results in a power loss from the bigger case - not an increase.
Eventually the thinner reeds needed, then go spastic at high rpm, as they don't have sufficient stiffness to keep the harmonic frequencies under control.

This factor has resulted in the guide volume of about 1.3 ratio, much smaller than the Rotary Valve as used by Jan.
We are now getting much closer to the power of the Aprillia with reeds, and its not the smaller case fighting pipe suction to fill the cylinder that is the limiting factor.
As a 125 with a 1.3 ratio has a case volume of about 540cc, over 4X the cylinder displacement, how is that factor limiting what the pipe can pull up the transfer ducts.

[TZ350]

TeeZee, you are making some pretty wild assumptions, for no reason, as EngMod quickly tells you if an idea is sound or not.
You say you have more relative case volume than the Aprilia that had about a 1.23 ratio, and im sure with 100 people working in R&D that if a bigger case was better, it would have been tested and subsequently used in GP's - why are you assuming bigger, is a better, if its never been tested in a controlled back to back.

Somewhere back a bit Jan Thiel commented that he would have liked to have progressively tried more crankcase volume as he felt he was not at the limit yet and there was more power to be gained with more volume and studying crankcase flow. I guess he saw more volume as a good idea. Unfortunately he retired before he could. The people who took over corrected Jan's big crankcase volume mistake and were left wondering why the engine made less power.

I suspect EngMod2T as good as it is, is based on known good engines. We never got to see the ultimate RS125 and how big its crankcase volume would have been.

And also the volume I have is what I naturally get with the conversion I have done. Anything less would require crankcase stuffing. I don't have the labour available of a large workshop crew to make the incremental well documented back to back changes. Can't be bothered myself. It runs pretty good as is. Makes more power than any of the other 50's I have seen on this dyno. And yes you are right, Engmod2T would be a good guide but I would need to measure the actual crankcase volume. Again, at this point, for the moment I can't be bothered. Works well as is and for now I have other ideas to pursue. Engmode might be a good guide for my ideas about variable RV inlet timing.

[TZ350]

.

TeeZee, you are making some pretty wild assumptions, im sure with 100 people working in R&D .....

A 100 people working in R&D Oooh such luxury but alas there is only me and Cully ....

I have other ideas to pursue. Engmode would be a good guide for these ideas about variable RV inlet timing. But for now I will checkout if its even physically possible.



It looks like I can swing the outer cover 25 deg. Using a Power Valve servo.

The idea is at low RPM to move the cover against the direction of RV rotation. Here there will only be half the inlet tract in line with the crankcase.

At high RPM the cover would be moved in the direction of RV rotation and the full inlet tract will be open to the crankcase.

So, low RPM, half the inlet tract diameter exposed, Rotary valve timing. 155/65

High RPM, cover rotated 25 deg. Full diameter of inlet tract open. Later effective Rotary valve timing 130/90

This idea is based on a paper I read where it showed that after you have established the correct inlet duration you could move the duration (timing} to make best power at different RPM.

Not sure if I have got this right, I guess the R&D Dept will have to fluff around and find out.

Will have a look to see what Engmod has to say. But I am unsure how well it can cope with the discontinuity of the inlet tract. Might have to be another suck it and see experiment.

[wobbly]

My point was you dont need 100 people to see if a case volume change is worthwhile.
On my computer it takes well less than a minute to rerun a sim with a new case ratio.
I dont understand why you would actually build something with an unknown case ratio, when you can test it in minutes in the computer, thats what you paid the money for after all.

[husaberg]

RG50 crankcase

Yes, Suzuki GP100/125 rotary valve parts.
AM6
.

rats


Tin worm or Rats?

section at top of pic of the valve?

[TZ350]

Tin worm or Rats? section at top of pic of the valve?

Good spotting. Overheating on an old motor from the valve rubbing on a slightly misaligned cover.

[TZ350]

TeeZee, you are making some pretty wild assumptions, for no reason, as EngMod quickly tells you if an idea is sound or not.
This factor has resulted in the guide volume of about 1.3 ratio, much smaller than the Rotary Valve as used by Jan.
We are now getting much closer to the power of the Aprillia with reeds, and its not the smaller case fighting pipe suction to fill the cylinder that is the limiting factor.
As a 125 with a 1.3 ratio has a case volume of about 540cc, over 4X the cylinder displacement, how is that factor limiting what the pipe can pull up the transfer ducts.

First off, let's be clear, I think EngMod2T is a spectacularly good program for simulating conventional 2T engines. It's an essential tool for any 2T tuner of a conventional engine. But I think it is limited by the conventional engines its based on. It can't predict what it does not know.

Now for crankcase volume. Let's explore it with a thought experiment. A two stroke works better, the better you can flush the cylinder and the better trapping purity you achieve the better the results. So logically, if you flush fresh charge through the cylinder for three weeks and a day the purity of the trapped charge is going to be 100%.

This is impactable due to the time constraints at 15.000 rpm. But something about 4X is good and maybe a little more might be better. So oversized case volume that comes easily from this conversion is not such a dreadful thing. It would be hard work with this engine to achieve a 1.3 ratio by case stuffing all for possibly little or no real return. Certainly not going to loose sleep over it and I post my findings so that others don't too.

Granted, with big case volumes there may be other issues like resonance in other ducts and the pipe. But a big case volume, bigger than 1.3 ratio does not look like the end of the earth for a RV engine.

There is also issues with managing a team of a 100 R&D types, group think and the personal preferences and the qualities of the leader. A Japanese Factory's GP development team stuck with 56/50 bore stroke for a long time while getting their noses wiped by the 50/50 team from another factory. If the 56/50 team had of had EnginMod2T they probably would have got past that blind spot quicker.

[wobbly]

I was never suggesting 1.3 was better, we know its not, but we know 1.23 is better for a Rotary Valve as its been done.
Your thinking says 1.2 or something is better, but have nothing to back up that theory.
Here is the RSA125 with a bigger case - sure as hell doesnt work on that engine with pretty much the accepted limit timings ( for the 250 ) of 91.5/142.5

Edit - Yamaha stuck with the 56/50.6 engine with the 3YL/4DP as it was based on the TZR case that was a current road bike. Kosinski and Harada won 250GP titles during that time with special factory only
stacked double crank, square , rotary valve TZM's. But it was obviously corporate policy at the time to utilise the road bike cases, nothing to do with short sightedness or lack of knowledge.
They went square in 2000 with the NX5 and won with Jaques on the 250, but those race only cases were sand cast and have had nothing but issues with main tunnels wearing out in no time.

[TZ350]

Your thinking says 1.2 or something is better, but have nothing to back up that theory.

My thinking is all about not being to hung up.

My experience with work on the Team ESE dyno, is if it is difficult to achieve the ideal.
A larger case volume on a RV engine than the currently accepted value is not the end of the earth, and that might be valuable re assurance for someone.

[TZ350]

.
Repairing the moth holes in the crankcase.



Sand away some of the inner RV plate.

Mask with sellotape.

Cover with J-B Weld epoxy steel resin.