ESE's works engine tuner

[jasonu]

..........


I recall reading about him bringing out a RS500 here over the Northern Hemisphere winter.
I guess at the time mid 80's that should have been a turkey shoot. Although who knows, he was going to do the street circuits as well.

I saw Richard Scott race the RS500 triple in Fanganui in the mid-late 1980's. I have some pictures of it somewhere. I know he had a bike shop in Taupo for a while too.

[TZ350]

Page 640 links list to be placed here.

I have been collecting what I can on pipes, there is more on pages 620 630 and 650.

Well its a bit of a stretch to try and be specific with so many variables involved but I will try.
What you are dealing with is a combination of static com and the dynamic com created by the efficiency of the engine spec, along with the added quirk of small bores being able to withstand more of both.
The more an engines overall spec is synergistic and SOTA then the less static com is needed nor is it in fact desirable.
So - with very average port/duct geometry, a very average pipe design, a very average ignition curve but using Avgas, then at the very least we need 15:1 full stroke com to get close to optimum, with EX durations between 196 and 202, where you need to be to make any power at all.
Avgas burns so close to 105 unleaded race gas, in power and reaction to com that its indistinguishable on a dyno, except that Avgas will always withstand more com or a lean condition better. Unleaded hates com but loves timing - as a general rule, the opposite of proper race gas or Avgas.
As Avgas is allowed, and we are discussing small bore race engines with sub optimal ports/pipes etc then I would say around 15.8 would work fine.
On pump gas, be it 91/95 or crap 98 then reduce this to 13.8 and wind in lots of static advance.
Avgas isnt created for what we are doing, but its cheap enough,available at any airport,and works real well when pushed to the edge of the tuning envelope.
The other issue is that to be effective, the squish clearance should be just above what would give zero clearance in an overev situation.
Thus any 50 or 100 cc bucket is able to run down at 0.6mm with complete safety, without running into issues of excessive squish velocity, unless you are well over 50% SAR.
But dont give me any grief when the thing melts using an 8 plug when any engine making any power at all, should have a 10 iridium as a baseline.

Sorry my mistake - I was referencing to water-cooled numbers.
For air - cooled, take one ratio less in both cases,ie 15.8 down to 14.8, again as the small bore/displacement allows alot more leeway..

Very interesting and Yes I would think it fair to measure 2-stroke CC's that way ........



It appears "compression cannot commence, before exhaust port is closed" untill you think about the role of the expansion chamber.



When you think about the plugging effect of the return pressure wave from the expansion chamber stopping fresh charge from spilling out of the cylinder as the piston starts on its way back up to close the exhaust port and maybe even stuffing some back in, in the last moments of closing.

You can see how compression of the fresh charge can happen earler than the exahust port closing point, effectivly making it a bigger engine when its "on the pipe". Some call it the supercharging effect..... whether it results in more than 100% volumetric efficency of the total swept volume I don't know, but it certainly gives more than a 100% of the swept area above the exhaust port.

There it is, the whole mistery of racing 2-strokes reveled in the last two posts, everything else is just detail, thanks Dutchee.

I posted about this a while ago.The chamber needs to be about the swept vol of the cylinder.
When its big enough, going bigger does nothing.
The connecting tube should be about 1/2 the header dia, as short as possible, with the controlling throttle plate as close to the pipe as you can get it, and as close to the flange as you can get it.
The resonant effect works up to a specific rpm, then kills power real quick, so you need an rpm "switch" to control a solenoid that quickly snaps the plate open at a set point,unlike a powervalve that can be ramped.
Many current cylinders have an ATAC volume within the casting that is opened/closed at the same time as the powervalve.
This is easy but for sure not the best setup.

The cylinders that use the powervalve action to open and close a port linking to a chamber within the casting are very limited by physical room.
We tested a couple of sizes of connecting tube and plate valve, and found that if it was smaller than 1/2 the header dia it didnt work near as well.Bigger than that and the flow disruption lost top end power.
We had a 20mm tube on a 43mm header for the 166cc cylinder size, with a 150cc chamber, and as I said this gave around 28% more power just below where the valve closed.

Two strokes like an ignition curve approximating to an inverse of the power curve.
With around 28* in the mid range, that ramps up from an easy kick starting 10* at idle to about 1500,2000 rpm.
Then as the bmep rises and the pipe gets in sync with the port we pull out timing in relation to the dynamic compression created by the wave action, to prevent detonation in the end gasses.
Most engines like around 15* of timing at peak torque, we then drop this away after peak to increase the heat released into the pipe.
We have a finite amount of heat energy to use to heat trapped combustion gas,heat the water, heat the piston/head, or release it into the pipe.
The ignition delay sets the amount dispersed into each element and how much this creates power at the crank is set by the interaction of each component part.

Apologies for not reacting a single time since 11 October. I did try to log on to this forum every day, but each time I got the message
The website cannot display the page HTTP 500. Most likely causes:
* The website is under maintenance.
* The website has a programming error.
I have had the same problem a couple of times in the past, but never as badly as these past two weeks. Any suggestions?

Now that I finally got through (heaven knows why, and heaven knows what will happen the next time I try to log on) I can give a short reaction to some (not all) of the items that went on during my unvoluntary absence.

In 1993 Itoh first rode a Honda NSR500 with water injection into the headers. No injection-water cooling (the small bottom radiator is just a part of the total cooling system as this picture will show), no double-wall constructions, no recirculation, just a simple total-loss system.
It did work to some extent; bottom power improved noticeably. The problem was that once you got the revs up and cut the water injection, the effect of the cooling water on the pipe resonance frequency did not disappear quickly enough. Mike Doohan used it once or twice but never liked it, so it was binned.
Aprilia tried such a system a couple of years before Honda did, in 1987, on Loris Reggiani's works 250 twin. It added 10 HP at 10.000 rpm and it took 0.000 seconds off the laptimes because Reggiani never ran below 11.000 rpm, so the system was scrapped, recovering weight and simplicity.

Somebody asked about the Aprilia's inlet disk diameter. From memory I would say it was 126 mm.

Optimized disk inlets do not generate pulses: you open the disk when the crankcase pressure is equal to the pressure just outside the disk. Opening it any sooner would cause a loss of mixture to the outside world; opening it any later would be a waste of time*area.
You close the disk when the inlet flow has come to a stop. At that moment the pressure at the outside face of the disk will be equal to the pressure in the crankcase, but it will be higher than the atmospheric pressure, so there will be some blow-back, but that does not come out of the crankcase (assuming your closing timing is spot-on); it is just mixture feathering back from the high-density zone outside the disk. For that matter, every conventional inlet system (disk, piston, reed) will show the same blow-back tendency. And it may not be even visible from the outside; maybe the cloud of blow-back moves just a few centimeters and never really exits the inlet tract.
By the way, closing an inlet disk too early (or revving the engine higher than the inlet system's frequency would like to) will generate serious blow-back because then the closing disk interrupts an inward-bound flow which will violently bounce off the disk.
You can observe this very nicely on a dyno: looking into the carburetter you can see the fuel spray exiting the mixing tube and curving towards the crankcase. But rev it high enough and you will see this curving change into a steep front of mixture.

PS: I am sorry to say that time does not permit me to answer private messages. I apologize, but I hope you will understand.

You are right, Husaberg. When you mentioned a small radiator, I did confuse the lower radiator with this tiny one. I cannot explain either what else it could be (I hardly expect Honda experimented with a water-cooled motor control unit) but then I can't see any sense in cooling that pipe injection water either; its container was built into the gas tank where the water will never pick up any heat.
And I know for a fact that the pipe injection system was total-loss. Honda (and Aprilia six years before them) already had a problem with the cooling effect not wearing off quickly enough once you got into the power band; the problem would have been far worse with double-walled light-alloy headers.

You can notice some blow-back at low revs + full throttle (only normal); it disappears at medium revs and comes back at high revs. So yes, this might be an indication of an early-closing disk.
You can try closing it 5° later but I would look at the inlet tract length first. If you can shorten that, you may solve the high-rev blow-back without the need for a late-closing disk. That would make setting the carburation a lot easier and it would also lower the inertia of the mixture column in the inlet tract, which in turn would make it easier to get this column up to speed; especially important when you have to use a small-bore carburetter.
O, and one more thing, TZ350. Fritz is German. I am a Dutchie and I spell my first name with an s .

I've got it, and some more papers from 'Prof Bob' as he was called in the GP-team. Robert Fleck too used a simple total-loss direct injection system.
Alas, these papers are at my home and I am not, and I won't be for some time.
Translating it back into English would mean removing the Spanish(!) voice that's talking through the original comment. I have enough Spanish, and some English as well, but this two-tongue Spanglish makes it hard to decipher. Anyway, it says there is water injected into the pipes; nothing new.
Not quite. Adjusting pipe or header lengths would require more mechanics and a large battery to drive the servo; Dutch double sidecar-world champ Egbert Streuer tried sliding end cones in his four pipes. As it turned out, over the entire GP-season there was only one corner (the hairpin at La source, Franchorcamps, Belgium) where it was a real advantage, so he dumped the whole package.

Exhaust power valves, if they're really good, shorten the exhaust timing, which costs torque because for true resonance you need an effective exhaust opening (and closing) period of 180 crank degrees.
Everyday exhaust power valves spoil the primary exhaust pulse, resulting in a weaker return pulse that won't do much harm, but not much good either.
Atac chambers lower the resonance frequency of the exhaust system, but a great deal of the return pulse energy is wasted in raising the pressure in the Atac chamber instead of the pressure in the cylinder.
The best way out of all of this would be a continuously variable transmission and I would have developed one a long time ago if only it had been allowed in GP racing...
I would appreciate that.

Bimota did that once: they built a pressurized thin-wall tubular frame with a manometer, so you could scientifically establish when the frame had developed a crack.
Added rigidity: sure. Maybe not so that you'd notice, but it certainly won't hurt. I once filled most cavities in my car with expanding building foam. It made the car feel twice as stiff!
Going electric on the movable pipes is not too bad either. I was talking about a Yam TZ500 four cylinder sidecar engine, but for a single the electricity consumption will not be all that much. Here are some pictures to wet your appetite:

"Is there still a place for them?" I should think so; look at the Aprilia RSA125. There the cover does two things: shield the pipe from a cold air stream, but more importantly, as you can tell by the shield covering only the top half of the pipe: shield the crankcase from radiated pipe heat.
How much difference? We can only guess (which I avoid as much as possible) because nobody ever took the trouble of measuring the difference on a real track (were measuring the power would not be simple anyhow). The crankcase-shielding will give more power everywhere and the pipe-heat conservation will give more overrun which is extremely import for lap times.

Page 350

"Is there still a place for them?" I should think so; look at the Aprilia RSA125. There the cover does two things: shield the pipe from a cold air stream, but more importantly, as you can tell by the shield covering only the top half of the pipe: shield the crankcase from radiated pipe heat.
How much difference? We can only guess (which I avoid as much as possible) because nobody ever took the trouble of measuring the difference on a real track (were measuring the power would not be simple anyhow). The crankcase-shielding will give more power everywhere and the pipe-heat conservation will give more overrun which is extremely import for lap times.

The exhaust open point has very little to do with creating power due to "pressure" on the piston for "longer" with lower timings.
The gas pressures soon after TDC ,that creates the real power, is up over 80 bar, the pressure at Ex open is a couple of bar at best.
Moving from 200* to say 190* creates jack shit extra exertion of pressure on the piston to create torque, that then creates HP.
But the real issue is that down at 190* duration we get a huge amount of superposition of the gas pulse exiting the exhaust, on top of the residual pressure at the port.
This adding of a new pulse on top of an existing residual pressure means the wave front running down into the header has a huge relative amplitude, and this creates a huge depression at the port around BDC.
This also means we have port/pipe resonance over a much wider range and at a much high higher level than can be achieved at 200* duration.
In a conventional design we are forced into a corner by needing to create as much BlowDown STA as we can, and raising the timing is the only available route.
This pushes us away from the ideal port/pipe interaction timings, but is a compromise we are forced to accept to create the + 200psi bmep's needed, to be competitive.
Just another small detail that many overlook, or are unaware of.

Neels van NieKerk auther of EngMod2T

As far as squish is concerned whether it helps or not depends on the residual turbulence at the time of combustion. As for squish quenching the flame at the edge of the squish band to stop detonation is not looking very likely. http://home.earthlink.net/~scloughn/id21.html

Attachment 250292 Tail pipe entry geometry http://www.google.co.nz/#sclient=psy...w=1024&bih=574

Attachment 250284 (2004) EngMod2T manual :- http://www.rddreams.com/neels/engmod2t.pdf

This manual is a bit dated but worth a look, hopefully someone can find a more recent version for us to look at.

Obtaining the EngMod2T suite of programs
The software price is $400.00. To purchase it email Neels van Niekerk at
vannik@mweb.co.za with a request. The software will then be emailed to you after which you
install it on your PC. The pre and post processors together with all the help files should then
work. EngMod2T requires a licence file to run. A one month evaluation license can be
provided. If after reading the help files you should decide to purchase the software contact
Neels van Niekerk to obtain banking details. Once proof of payment has been received the
licence file will be sent to you. The licence is for one computer only.

You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.
It is best to concentrate on getting all dimensions correct for maximum power. In the high gears you don't ride low revs and in the low gears you'll have enough low-down power left to pull a wheelie or spin out the rear wheel (I'm not talking about buckets though, so you might want to reconsider your case).
If you have a decent setup for angle*areas, pipe, carburation and ignition, the necessary overrev potential will come naturally; no need to sacrifice maximum power in order to make it rev a little higher.

The wide septums between the transfer ducts is there for two reasons.
One it reduces the duct entry area, and thus the ratio between the port and entry areas.
This drops the volume of the duct.A smaller volume sitting at the port has less inertia that the pressure ratio across the port has to accelerate into the cylinder.
Also consider that if you calculate the delivery ratio at full power and compare this to the cylinder swept volume of the cylinder, the air/fuel mixture sitting in the ducts
is more than enough to fill the cylinder - the is very little "flow" from the case, around the duct and into the cylinder in reality.

Secondly, the front and rear wall radial angles of the ducts are maintained all the way from the port, out to the duct entry.
As in 4T ports, trying to "bend" flow in two dimensions concurrently,lowers the bulk flow rate considerably.
Thus the ducts taper all the way from entry to exit, but only change direction in the one plane, around the short turn to give the correct axial entry angle.
The old bullshit you see of sharp divider edges is just that.
Only supersonic aircraft have sharp leading edges on the wings,and we certainly arent dealing with supersonic flow in transfer ducting.
Any flow loss due to the corners on the flat topped septums is way offset by the better directional control and reduced volume of the duct acting to fill the cylinder quicker.

It matters, Pete, as a lot of Italian kart engine manufacturers and tuners will reluctantly confirm. They all copied the Aprilia cylinder and while they were at it, they could not resist correcting the 'errors' that Jan Thiel had left behind. And then they were surprised when the engine made less power instead of more .
It's not that simple to improve the best two-stroke cylinder in history .

The outer transfer duct radius is utterly unimportant; there the charge has no option but to go where the duct wall leads it. But the inner duct radius is very important: it should be as large as possible to avoid flow detachment. If you manage to keep the flow clinging to the inner surface (the Coanda effect), there will be less pressure-absorbing turbulence, so the flow will meet less resistance, transport more mass and deliver it where you want it to go.
The golden rule of flow: look for sharp inner edges and remove them. It always works.

The radii at the bottom bore edges, as visible in the picture above, yielded 1 HP; that's about 2% of the total power. The egdes where the transfer port windows cut the bore, should not be radiused; you do not want to promote inflow of waste gas into the transfer ducts. Here only the top and bottom edges should be chamfered lightly to make life easier for the piston ring.
There should be no widening just before the port exit; the duct cross-section area should gradually move from entry area to exit area. And with the inner curvature of the duct fixed, this more or less lays down the shape of the outer curvature.

Assuming that the flow in a duct will accelerate faster as a result of narrowing that duct is an ineradicable misconception. If it were true, it would mean that a duct narrowing to zero would yield an infinite flow velocity......
Flow velocity depends on the pressure difference between entry and exit of a duct, and in the case of an engine, where the flow constantly accelerates and decelerates, it also depends on the column length of the mass in the duct. It does not depend on the column's cross-area; twice the area would mean twice the mass per mm column length, but it also means that the cross-area exposed to the pressure difference is twice as big.
A smaller cross-area can have the effect that because of the reduced mass flow the pressure in the crankcase does not fall as quickly, which in turn may lead to a longer-lasting acceleration of the flow and thus a slightly higher top speed. But it will also mean less mass transport during the transfer phase.

The duct entry area of the Aprilia cylinder's B-ports is slightly smaller than their port exit area. This stems from the old obligation to develop cylinders that had to fit the existing crankcases of the Aprilia RSW engine, of which there are hundreds around. the RSA engine did not have this limitation, but simply enlarging the B-duct entries disturbed the scavenging, so the ducts were left as they were (and remember: while the B-ports' exit areas are only open part of the time, the entry areas are open all the time).
The transfer timing is 130° for the A-ports (they are really close to the auxiliary exhaust ports) and 132° for the B-ports and the C-port.

[TZ350]

Someone asked what I used connecting my laptop to the Ignitec.



I use Windows XP, this USB to Serial converter and the driver that came with it and a proper Serial RS 232 cable, not a 9 pin extension cable and most importantly a 5K resistor plug cap, a resistor plug would be good to but I have not tried that yet.

Most of my computer freezing problems went away when I used the cable adapter and completely vanished when I fitted a 5K plug cap.

[speedpro]

I recall piling into the sweeper at Baypark on my GSX1100. Had the left pipe dragging hard in an effort to stay in front of a bike I could hear behind me. More or less got to the back straight and if I recall correctly Discombe shot past like I'd had some sort of mechanical failure. It was a long time ago but it still sticks in my mind.

[Rick 52]

Crank shaft balance factor ...I have a TF125 that I picked up in a RG50 frame some years ago and it's been a great little engine with very little vibration, the engine is now ready for a little work and a TS gear box so while the cases were open team ESE and myself were keen to measure the crank balance factor as people have said TF engines vibrate a lot and crack pistons and my bike has not cracked a piston in the time I have raced it.
Teezee helped me understand what we were doing with the balance factor and measured up the new gearbox that will fit in with out any work ..the ideal crank balance factor for my bike is..49%.of the portion of the "Reciprocating Mass" that is balanced by the "Counter Balance" portion of the crankshaft because that is what it worked out to be and it looks standard apart from the holes in the crank being filled with resin ..now to get it back together before he weekend ..

[Grumph]

Crank shaft balance factor ...I have a TF125 that I picked up in a RG50 frame some years ago and it's been a great little engine with very little vibration, the engine is now ready for a little work and a TS gear box so while the cases were open team ESE and myself were keen to measure the crank balance factor as people have said TF engines vibrate a lot and crack pistons and my bike has not cracked a piston in the time I have raced it.
Teezee helped me understand what we were doing with the balance factor and measured up the new gearbox that will fit in with out any work ..the ideal crank balance factor for my bike is..49%.of the portion of the "Reciprocating Mass" that is balanced by the "Counter Balance" portion of the crankshaft because that is what it worked out to be and it looks standard apart from the holes in the crank being filled with resin ..now to get it back together before he weekend ..

There is no "ideal" balance factor for a single....yours happens to work acceptably in that frame.
If they have a rep for vibration in the std frame, 49% as the std balance factor explains some of that.....

[wobbly]

WinDoze 7 works fine with a good quality serial adapter as long as you install the adapter driver as well as the newer downloadable driver from Ignitech.
All modern bikes and cars have resistor caps, and its getting difficult now to buy a non resistor plug.
The combination of resistor plug and cap form a low pass filter in concert with the capacitance of the plug lead, killing RF that usb is very sensitive to.
A USB optical isolator does help as well, but in the main, keeping the coil drive wire away from trigger and TPS inputs will solve crashing issues.
The newer program does have some issue with not doing a full reprogram when running on the dyno - and doing multiple changes, but simply switching the ecu on/off quickly resets it,and it then works fine.
I have used top quality spiral wound plug wire and ditched the resistor caps, for a very high power spark setup, and this worked equally well.
The rare earth fine wire iridium/platinum electrode and ground strap plugs are so good now that NGK should offer a trade in discount so all you tight arses finally get rid of all the
B10EGV and N82G plugs that have been lying in the toolbox for 25 years - as you SHOULD be using the resistor type..

[TZ350]

...the ideal crank balance factor for my bike is..49%...

There is no "ideal" balance factor for a single....yours happens to work acceptably in that frame...

True ... and its why Rick said "ideal crank balance factor for my bike". We have always said there is no universal ideal, only what works best in your circumstances, there may be some general factor that gets you into the ballpark but the ideal or best for a particular setup is found by trial and error.

[twotempi]

True ...The rare earth fine wire iridium/platinum electrode and ground strap plugs are so good now that NGK should offer a trade in discount so all you tight arses finally get rid of all the
B10EGV and N82G plugs that have been lying in the toolbox for 25 years.r.

What do you mean !! Paid good money for all the plugs rattling around in the bottom of the toolbox

But I am not tight as someone one I know who bead-blasts all his EGV plugs at the beginning of the season so he has a fresh lot for that season.

Has done it for years with no apparent problems. Racing on a pension means you have to use what you own !!

Maybe the "old" EGV plugs were better quality !!

[wobbly]

The new type 7376 plugs are ideal for bead blasting after every meeting.
As I insist on plug chops after every race and change the jets at least 3 times a day when doing "real "racing, reading the insulator and ground strap
is impossible if the thing is covered in oily shit from idling around - at all.

[husaberg]

The new type 7376 plugs are ideal for bead blasting after every meeting.
As I insist on plug chops after every race and change the jets at least 3 times a day when doing "real "racing, reading the insulator and ground strap
is impossible if the thing is covered in oily shit from idling around - at all.

When i was young i always felt so guilty using these (far right) but long ago nearly every country garage (Remember those) had a champion or similar one complete with tester.
After Wobs post.. maybe not so much......... i was told they damaged the insulator and rounded off the edges etc (They were filled with garnet i think),
The old man still has one, Er... i might just have to liberate it.............

[speedpro]

True ... and its why Rick said "ideal crank balance factor for my bike". We have always said there is no universal ideal, only what works best in your circumstances, there may be some general factor that gets you into the ballpark but the ideal or best for a particular setup is found by trial and error.

I rebalanced my TS engine. The differance in vibration was great enough for Pete Sales to comment when I was next visiting for more dyno tuning. My bike vibrated at higher revs so it needed a lower % balance factor. As a trial, no maths involved, I put a slug of aluminium into the larger hole in each crank web next to the big end pin. I never did check the numbers but it worked perfectly. The motor vibed a bit low down but was sweet when being raced. I really wouldn't worry about the maths. Just check where it vibrates, high or low compared to where you use it and adjust the balance factor an amount.

[richban]

I rebalanced my TS engine. The differance in vibration was great enough for Pete Sales to comment when I was next visiting for more dyno tuning. My bike vibrated at higher revs so it needed a lower % balance factor. As a trial, no maths involved, I put a slug of aluminium into the larger hole in each crank web next to the big end pin. I never did check the numbers but it worked perfectly. The motor vibed a bit low down but was sweet when being raced. I really wouldn't worry about the maths. Just check where it vibrates, high or low compared to where you use it and adjust the balance factor an amount.

So do you think its possible to get an FXR crank to work without a balance shaft?

[speedpro]

I have removed the balance shaft from my current MB engine and rebalanced the crankshaft. Maths were involved this time and they told me I had to increase the balance factor of the crank. It works fine on my MB so I would expect you could do it to your FXR.

The MB balance shaft weight assisted the crankshaft balance in line with the bore and opposed it at right anges. By removing it I reduced the amount of rotating mass trying to balance the reciprocating mass which was the right direction to go with the increased revs but it was too much of a reduction so I had to increase the % on the crank itself.

[Yow Ling]

So do you think its possible to get an FXR crank to work without a balance shaft?

Ive seen a few come out , then the bikes fall to bits so they go back in, except for the guys who leave the bearing in the blind hole because its too hard to get out, they usually need new crankcases, crank and gearbox after 10 minutes running