ESE's works engine tuner

[Yow Ling]

the relay contacts might be a bit noisy compared to an open collector transistor, also easy to contaminate with virtually no current

[TZ350]

Can't you just wire directly to arduino from ecotrons ecu.? I don't think you will need the relay as there is no current.

With a relay there is no forward resistance either.

I am not sure what the Ecotrons power switch is looking for and it is the 0.5V across the collector emitter junction at saturation that concerns me. It might look like a dirty contact to the Ecotrons.

Anyway I will start with the relay but would prefer to do without it if it proves possible.

[TZ350]

It will sadly enough not be a smooth transition when switching maps i guess.

I called it a map but in reality it is a table of Lambda values that are used to divide the current cell value in the active map to enrich-en it for maximum acceleration power, hence the name "Power Switch".

So instead of dividing the current map cell value by say 0.85 to enrich-in the mixture for acceleration I could divide it by say 2 to lean it off because the pipe is not sucking and there is 50% less air being drawn through the motor.

[TZ350]

the relay contacts might be a bit noisy compared to an open collector transistor, also easy to contaminate with virtually no current

An open collector transistor sounds the go but I am just feeling my way with this.

To tell if the motor has or has not fired I am very tempted to try and measure the actual combustion pressure.

[Brett S]

Would a crank encoder be able to sample a period of time after ignition event, be fast enough to determine whether combustion took place or not?
This may be trying to determine the impossible though, possible better than my optical sensor pointing up xfer idea.

[Frits Overmars]

I am very tempted to try and measure the actual combustion pressure.That's the way to go anyway. And it will make a deto sensor superfluous - provided your pressure sensor is detoproof.

[Niels Abildgaard]

To tell if the motor has or has not fired I am very tempted to try and measure the actual combustion pressure.

Do You really need the absolute pressure or only the presure history 30 degree on both side of Top Dead Center?
If it is more or less symmetric it has not fired and if not it has.
In that case two small piezo disc with holes under one of the cylinder- head holding down nuts can maybe work.

[Flettner]

opps wrong message

[Nath88]

Would a crank encoder be able to sample a period of time after ignition event, be fast enough to determine whether combustion took place or not?
This may be trying to determine the impossible though, possible better than my optical sensor pointing up xfer idea.

This is the most common misfire detection method used by OEM ECUs. Compare the time between teeth of the crank X degrees before TDC and X degrees after. Worth investigating, you can buy off the shelf ICs for that exact purpose. I think the trouble areas would be when the clutch is dropped or slipped, the rapid change in crank speed might cause false indications. Although you could probably measure the overall crank acceleration as well and have it as a factor in the output.

[Nath88]

.
The plan is to have a pulse trigger on the flywheel that corresponds with the exhaust port opening and a pressure sensor in the exhaust tract close to the exhaust port.

I like this approach. The pressure pulse delay from the port to the sensor is significant (but should be more or less constant) so suggest having a delay in the code from the exhaust opening point before sampling. Then take samples over 0.5ms or so and use the highest value. Then compare to your threshold value, I'd have that as an input from a potentiometer, but you could just hard code it. If its above the preset threshold, set the output to your relay high, and wait for the next trigger. You might want to have an output toggle when the sampling window is active, so you can watch the input and the output on a scope to dial in your delay.

If your trigger is not exactly at exhaust port open, you'll need to add a delay that varies with RPM. I'd probably set it 10 degrees early and incorporate that anyway. Measuring time between triggers for RPM.

If the microsquirt could do all this, tuning would be much easier.



Or there are some of these Wika pressure transmitters lying around work. There is a variety of pressure ranges up to 500 bar. So I could easily measure the combustion pressure directly and when its over a certain threshold ie the engine has fired then the 4-20mA output through a small power transistor could be arranged to switch the relay.

Response time of the sensor will be the only issue, testing will tell. This is where the piezo will excel over the pressure sensors.

The relay board you have would most likely switch the ground for the relay coil, you could connect the ecotrons input here to eliminate the relay itself.

Directly measuring combustion pressure would be the duck's. Maybe incorporate one of the Beru PSG range of diesel glow plugs with built in pressure sensors? They're very long though.

[Nath88]

Do You really need the absolute pressure or only the presure history 30 degree on both side of Top Dead Center?
If it is more or less symmetric it has not fired and if not it has.
In that case two small piezo disc with holes under one of the cylinder- head holding down nuts can maybe work.

That could work well, integrate the output of the piezo from -30 to +30, if it's substantially positive, fire has occured, and we should expect an exhaust pulse. Might go looking for piezo washers now.

[peewee]

hey guys can anything be said about the color on my piston top ? this is after about 1/2 gal nitro. so far 15% mix was the highest I could reach as the needle was just to lean in the throttle closed position. its mostly light brown with alittle darker color near the exh side but some of the dark color is shadow from the camera. its really good shape with no erosion at the edges or anything else that would indicate deto or other tuning problems. honestly I was wondering if the brown meens im just a bit lean still and its heating the crown a bit to much or its ok ?

ive since picked up a virgin head in order to drop the com ratio. 11cc more than the previous head is what I need to add. in order to accomplish this, the head has to be raised so ill spend some time over the weekend welding the face and chamber then remachine it. also I had one of my existing needles richened in the slide close position, hopefully its enough. and the other thing is I increased the float bowl capacity even further incase fuel flow into the bowl cant keep up, as the third jet is half open now and Im not sure if ill need a fourth jet as I get closer to 20% mix but that remains to be seen just yet. my goal is to get to about 23% nitro by volume /approx 30% by weight. I think the lower end is strong enough as it has prox cr500 conrod with welded crankpin and large nj207 germany roller bearings

[TZ350]

.

In cylinder combustion pressure sensors:- https://www.avl.com/pressure-sensors-for-combustion-analysis1


333420

https://www.avl.com/-/GO15DK

The GO15DK has the slimmest contour due to an M3 cable connector and is an M5 monitoring sensor especially suited for pmax monitoring with maximum amount of knock. The Double-Shell™ design decouples the piezoelectric elements from negative influences of mechanical stresses that can occur due to the mounting of the sensor into the engine. In addition to this, it has an improved membrane material and geometry. This makes the sensor to the standard solution for monitoring with maximum levels of knock.

[jonny quest]

I've designed and built a lot of 2 stroke pipes back in the day, one thing that always baffled me....

Some engines don't care if youput a 360 loop in header, some engines loose a lot of power with the slightest bends? This is compared to a straight test pipe.

Why are some engines much more sensitive?

[Tbh37620]

This ran over a welded in central port bridge that had added boost ports down each side.


Wobbly, do you have any photos or info on this welded in bridge(Parent materials, filler metal, etc)? I have several cylinders I would like to weld bridges into to expand the width of the ports. Id imagine the H1 cylinder was a cast iron sleeve in aluminum casting?


Thanks,

[TZ350]

333428

Suzuki GP100 with an NSR250 cylinder.

333422

I have been working on a water cooled exhaust manifold for the Suzuki GP/NSR 110 engine.

333423

Chambers is making good progress fitting it all into Av's old NF4 rolling chassis. He is even re cycling the original Honda RS125 NF4 expansion chamber. It will be a fun bike for us to ride.

333424

And could be very interesting if Av takes her old NF4 for a spin.

333425

Av peddling number 21 up the inside to take the win.

[mr bucketracer]

the front of the chamber is mighty close to the front wheel

[diesel pig]

I have to agree, When I fitted the radiator to my NF4 frame I did the same thing with unscrewing the fork springs and bottoming out the forks then fitting up the radiator with similar gap. I don't know if it is the tyre growing or the forks bending under braking or maybe a bit of both but there is a black mark on the bottom tank of the radiator after each race. I hope to fix it with a different radiator I have coming next week.

[TZ350]

.

Yes we think you are right. Chambers is looking at ways to move the engine back. Even 10mm would be a help.

[Frits Overmars]

Chambers is looking at ways to move the engine back. Even 10mm would be a help.Why not take the easy route and move the header back? Two sawcuts and one weld, and you're done. Or better still, build your own pipe, because I doubt that an NF4 pipe has the optimum dimensions for an engine with a different cylinder capacity and a different exhaust timing. The engine might feel more comfortable with a smaller initial header diameter.
333429
BTW, for their NF4-successor NX4, Honda changed the complete engine layout in order to shorten the wheelbase and move the engine closer to the front wheel. Even 10 mm would make a difference in handling and feedback.

BTW2: tire growth on this kind of tire is wellnigh negligible. The wheel displacement is mainly due to the NF4 forks bending. The NX4 forks, or indeed most upside-down forks, are a lot better in this respect.

[ken seeber]

Wobbly, do you have any photos or info on this welded in bridge(Parent materials, filler metal, etc)?
Thanks,

I'm pretty sure Wobbly is away in Las Vegas for the SKUSA car park racing bonanza.....

[Tbh37620]

I'm pretty sure Wobbly is away in Las Vegas for the SKUSA car park racing bonanza.....

Thank you for the heads up on that. I will keep an eye out for when he returns and posts next :2thumbsup

[TZ350]

... better still, build your own pipe, because I doubt that an NF4 pipe has the optimum dimensions for an engine with a different cylinder capacity and a different exhaust timing.

At first blush you would think so but it has proved not to be a problem.

333435

We have done a bit of work in that area and Chambers has got quite good at constructing pipes.

333434

Expansion chambers, I started with a RGV250 pipe then modified it to RM125 C specs then in 2009 started using a NF4 chamber.

At exhaust opening 80 deg ATDC for all the pipes all the torque curves were flat.

333436

Typical torque curves, flat at Ex 200 duration and 70% wide and as the port width and duration was increased we got more power but the torque curve became steeper. This was typical of all four pipes RGV, RM125C, NF4, NX4.

The difference between the engine setups and pipes was the rpm at which they made maximum power. As the max power and rpm that max power was made at increased, the width of the power spread also increased, which was very handy.

When I first started using the NF4 pipe in late 2009 someone else expressed doubts about its suitability. But after a bit of thought I realized a good pipe like the NF4 or NX4 could cover a wide range of engine development.

As I developed the engine over the years I found the same length pipe can stay in tune with the new engine. Because, as the two physical effects of increased exhaust heat from more power (a longer pipe is required) and increased RPM (a shorter pipe was required), these two things neatly balanced each other.

A few calculations showed me that:-

Less power and exhaust heat plus lower max rpm equaled the tuned length of the NF4 pipe.
More power and exhaust heat plus higher max rpm equaled the same tuned length of the NF4 pipe.

And as the power and rpm continues to go up I expect the NF4 pipe to continue to be suitable.

So one pipe can be a good friend for a long time and like good friends, if you have a pipe that works, stick with it is my opinion.

There is still a lot to be gained within the engine by looking at the overall transfer ratio and trapping efficiency and the direction of the transfer streams.


BTW, for their NF4-successor NX4, Honda changed the complete engine layout in order to shorten the wheelbase and move the engine closer to the front wheel. Even 10 mm would make a difference in handling and feedback.

333437 333439

My own GP/NSR110 engine is tipped well forward and uses a NF4 pipe. The GP/NSR110 dyno graphs are pretty much the same as the earlier air cooled GP125 ones, the benefit will be the water cooling. Tipping the engine forward allowed me to move it forward but the angle of the engine meant I needed to run a dry sump gear box with oil sprayed over the gears.

I would love to experiment with pipe building but so far I have been unable to simulate anything in EngMod that exceeds the benefits of the NX4 or NF4 pipes. So I won't be cutting and welding thin sheet any time soon.

[husaberg]

BTW, for their NF4-successor NX4, Honda changed the complete engine layout in order to shorten the wheelbase and move the engine closer to the front wheel. Even 10 mm would make a difference in handling and feedback.

BTW2: tire growth on this kind of tire is wellnigh negligible. The wheel displacement is mainly due to the NF4 forks bending. The NX4 forks, or indeed most upside-down forks, are a lot better in this respect. i am not so sure it was just to shorten the wheelbase as the NX4 went to a linkage rear shock which entailed a longer swingarm. Which is a benefit in itself.
The stacked layout with a balance shaft of the NX4 allows the engine to be mounted further forward. whist maintainng an acceptable wheelbase another plus.
With the rejigged engine an the different angle on the spars it endied up a few inches shorter with more forward weight bias.

My thoughts are that people are running into clearance issues as the original NF4 chassis geomerty was based on Skinny 18 inch wheels. These days people tend to drop the forks pretty low in the yokes to get them turning sharper as all these buckets now all have modern size 17" wide wheels fitted to them. plus the riders tend not to be 50-60KG teens.
The NX4 ws designed arround these factors from the very start. Other than the fatties.

<tbody>
NX4
WHEELBASE 1215mm (47.8 in)
Caster angle 23 ° 30'
Trail length 84mm (3.3 in)

NF4
Wheelbase 1,260 mm (49.6)
Caster angle 25 °
Trail length 95 mm (3.74 in)



</tbody>

[TZ350]

.

An interesting read of one mans adventures racing his Post Classic TZ250 http://www.natsforum.net/viewtopic.php?f=3&t=1130

[jbiplane]

Hi guys

Want make V 2-stroke with 90 degree V-angle. I saw exist variant of V when conrods share the same finger
http://fastpic.ru/view/98/2017/1118/0656f24c6dd97108113c332526ca4442.png.html

but seems 90 degree pins ofset have balance and smoother torque variation. Possible make engine which
balansed like opposite and have smoothness of inline.
http://fastpic.ru/view/98/2017/1118/4f5364299f257dd685b211f15091c1dc.png.html

Medium crank disk separates crank volumes in both cases. Anyone saw this idea already implemented?

(sorry dont found better way how direcly attach pictures to the post)

[Frits Overmars]

Want make V 2-stroke with 90 degree V-angle. I saw exist variant of V when conrods share the same finger... but seems 90 degree pins ofset have balance and smoother torque variation. Possible make engine which balansed like opposite and have smoothness of inline.
Medium crank disk separates crank volumes in both cases. Anyone saw this idea already implemented?Hi Valery, a 90° V-twin with both con rods on the same big end pin has a very good balance, especially when you can keep the cylinder center lines close to each other.
It will also have a smooth torque with less variation over a crankshaft revolution than any 180°-firing twin.
A 90° V-twin with 90° offset between the big end pins would be very bad for balance, vibration and torque variation.

The idea of a center crank disk that separates the two crank volumes, is not new. It is used in many two-stroke outboard V-engines like the Suzuki V-6 below-left.
Is has also been seen in motorcycle racing. The pictures below show the 250 cc V-twin built by French dentist Jean-Bertrand Bruneau, better known as JBB.
The drawing on the far right shows his last V-2 crankshaft.
333448 333450 333445 333446 333447 333449

[WilDun]

Hi Valery, a 90° V-twin with both con rods on the same big end pin has a very good balance, especially when you can keep the cylinder center lines close to each other.

A 90° V-twin with 90° offset between the big end pins would be very bad for balance, vibration and torque variation.

The idea of a center crank disk that separates the two crank volumes, is not new.
Is has also been seen in motorcycle racing.


I do realize that I may not be quite up with the play here!.... but if the centre disc rotates (which it must do,) how much clearence is there between it and the crankcase and why does it have what looks like an "O" ring groove .... surely not?

[jato]

The center disc works as a labyrinth seal (no contact between surfaces and you are right - no o-ring) the groove is part of the labyrinth. probably in the order of 0.5 mm radial clearance on the lands and maybe a little less axially to allow for the inevitable bit of crank flex

[diesel62]

The center disc works as a labyrinth seal (no contact between surfaces and you are right - no o-ring) the groove is part of the labyrinth. probably in the order of 0.5 mm radial clearance on the lands and maybe a little less axially to allow for the inevitable bit of crank flexPiston ring seal by the looks of it

Sent from my SM-P555 using Tapatalk

[jato]

I stand corrected - looking at the previous photo yes i see it. there must be some serious surface speed there at full revs...

[Grumph]

I stand corrected - looking at the previous photo yes i see it. there must be some serious surface speed there at full revs...

OMC outboards of the 60's had silver plated rings in that groove - sprung against the crankcase wall. At least you'd think they would be well lubricated.
And they were seldom called on to go over 4500RPM.

[TZ350]

333462

With an old Suzuki GP125 air cooled cylinder and basic hand tools, how good a port job could you expect.

333461 333460

A drill press worked pretty well at hogging out the B and C transfer ducts. The B port windows were widened and the C port opened up.

333464

Suzuki GP125
27 rwhp for Inlet 140/80 Trans 114 Ex 80 and 70% NF4 pipe.
30 rwhp for Inlet 140/80 Trans 114 Ex 78.5 and 75% NF4 pipe.

333465

NSR MC21 in all its lovelyness.

333459

Suzuki GP fitted with a NSR MC21 Cylinder
28 rwhp for Inlet 140/80 Trans 114 Ex 80 std shape NX4 pipe.
30 rwhp for Inlet 140/80 Trans 114 Ex port roof leveled off NX4 pipe.

Not startlingly different for all its factory lovelyness.

Good old hand porting work compares Ok to the Honda factorys performance sports cylinder.

Just saying, you don't need a lot of flash stuff to get a good enough result .....

[Frits Overmars]

if the centre disc rotates (which it must do,) how much clearence is there between it and the crankcase and why does it have what looks like an "O" ring groove .... surely not?
OMC outboards of the 60's had silver plated rings in that groove - sprung against the crankcase wall.That's still state of the art - except the silver plating. The radial clearance of the centre disc in the crankcase can be quite liberal; sealing does not depend on it,
but on the clearance of the stationary 'piston ring' in the disc's groove. And that ring settles itself in the crankcase so that it's not pushed left and right anymore.
Wear is not a problem, as the pressure acting on the ring is less than 1% of the pressure acting on a 'real' piston ring, and the local temperature is modest as well.
Here's another picture of the JBB crankshaft.
333466

[jbiplane]

Thanks you guys for valuable comments. I did some computer modeling and realyze that classical V "common finger" good enough and my idea of 90 degree pin offset require more bearing supports on shaft. Smaller torque variation not enough reason then.


Anyone know if intermediate part of jbb crank were one solid part or welding (press fit) of finger and disk?

Finally I am going to make 140cc V with 9500 rpm on max power which should weight below 3000 grammes including fuel injection.
It will be rather long ~4 month project. I think if I will make crancase precisiously then will dont need sealing ring on crankshaft.

[lohring]

This is the crankshaft I built for a 180 degree twin I'm slowly working on.
333467
It will need a balance shaft. The same design will work for a 90 degree twin. It will need more balance weight in any case.

Lohring Miller

[Niels Abildgaard]

Finally I am going to make 140cc V with 9500 rpm on max power which should weight below 3000 grammes including fuel injection.

https://i.imgur.com/9RprD0t.jpg
https://i.imgur.com/n36caso.jpg

What kind of exhaust system?
If the pots are powerfull enough You probably do not need to divide the crankcase volume.

[WilDun]

Probably a very slight gap allowing communication between the (half) chambers wouldn't be a disaster in this case. but then what about the cylinders (axially) overlapping, what sort of arrangement is used to overcome that?
I understand that it all is well proven of course, but was just curious as to how it all works.

Update: Sorry I missed what came after my earlier question about the disc and when I've had my breakfast I'll read it all up! :rolleyes:

Ok, so it seems to me that in effect it is really a labyrinth seal with maybe a little touching now and then.

I have heard that if the crankcase cavity is left undivided, (ie with 'V' cylinder arrangement) that the flow into the the lagging cylinder is always compromised - is this true? and of course there is the inevitable loss of pumping pressure for the second cylinder, but some people do seem to believe that this is irrelavent these days!
If I'm wrong, please say so - don't hold back! (it may improve my learning) :)

[WilDun]

This is the crankshaft I built for a 180 degree twin I'm slowly working on.
333467
It will need a balance shaft. The same design will work for a 90 degree twin. It will need more balance weight in any case.
Lohring Miller

So I guess that gives the same piston phasing as a 180deg parallel twin but in boxer twin configuration? - would it justify the added complication and weight of a balance shaft (and crank bobweights)?

[peewee]

333428

Suzuki GP100 with an NSR250 cylinder.

333422

I have been working on a water cooled exhaust manifold for the Suzuki GP/NSR 110 engine.

333423

Chambers is making good progress fitting it all into Av's old NF4 rolling chassis. He is even re cycling the original Honda RS125 NF4 expansion chamber. It will be a fun bike for us to ride.

333424

And could be very interesting if Av takes her old NF4 for a spin.

333425

Av peddling number 21 up the inside to take the win.

couple years ago i had cr500 with nearly those same timings that was used for racing on sand hills and it had a problem falling off the powerband unless shifted perfect and even then it was a bugger. maybe the pipe or something else was wrong. then again sand can be like riding with the brakes applied. ported a new cylinder with lower timings which worked far better for that kind of racing

[Frits Overmars]

couple years ago i had cr500 with nearly those same timings that was used for racing on sand hills and it had a problem falling off the powerband unless shifted perfect and even then it was a bugger. maybe the pipe or something else was wrong. then again sand can be like riding with the brakes applied. ported a new cylinder with lower timings which worked far better for that kind of racingRiding in sand requires a broad powerband and a close-ratio gearbox because the rpm-drops during upshifts are far greater than you would expect from just looking at the gear ratios.
With a spinning rear wheel your crankshaft may be doing 8000 rpm but your riding speed may only correspond to 4000 rpm.
During an upshift the spinning stops and after the upshift your crankshaft rpm wil have dropped well below 4000 rpm, where no-one is home, power-wise.
MX-practice is to grab the clutch and send enough torque to the rear wheel to get it spinning again. MX-sidecars with 800cc two-stroke singles are the worst:
some riders cover the whole track in third gear.

[Greg85]

I discovered that making the underside of the transfer ports even with the piston in BDC
was very important: considerably more power, less detonation and far better piston cooling.
We started to have the exhaust ducts CNC machined in 1999 I think.
But first we had to overcome the new fuel regulations in 1998
102 octane had to be used instead of 130 octane.
We expected BIG problems.....
But within a couple of month's we had more power than before!
The compression ratio was lowered from 19,5:1 to 16:1
And the tailpipe restrictor was made 0,25mm bigger.
Then a very serious combustion chamber development was started.
The result was that parallel squish was the best, with a squish height of 0,75mm
Less squish height would give more torque but less revs.
At 0,45 the piston touched the head....
Then a head insert with a much wider squish band (50% of cylinder surface) was tried.
And that proved to be the final touch.
We now had more power than with the 130 octane fuels, and less problems.
The sharp edge between combustion chamber and squish band proved to be very important.
Even a small radius would give 0,5HP less..

hi jan you used a piston domed in the rsa it was doing more power than the conic piston? what squish angle did you have with the piston domed? thanks

[Frits Overmars]

No squish angle Greg, but a squish dome, parallel with the piston dome, as Jan wrote.
I guess you haven't noticed the RSA head drawing that I posted some time ago, so here it is once more.
333472

[Greg85]

No squish angle Greg, but a squish dome, parallel with the piston dome, as Jan wrote.
I guess you haven't noticed the RSA head drawing that I posted some time ago, so here it is once more.
333472

thank you very much for your contribution frits sorry I did not see this post very interesting

[Niels Abildgaard]

Finally I am going to make 140cc V with 9500 rpm on max power which should weight below 3000 grammes including fuel injection.
It will be rather long ~4 month project. I think if I will make crancase precisiously then will dont need sealing ring on crankshaft.

3Kg will be possible.Close at least

http://www.agm-engine.co.uk/agm6060cc-rc-model-petrol-twin-engine-70hp-with-muffler-p-325.html

And spare parts list

http://www.dle-engines.com/dleg0060.html

I will try and sketch a V-2 crankshaft plus bearing system using these parts.I have quite some already and they are cheap.
Are there any classes for racing where a twincylinder two stroke is wellcome?

[Niels Abildgaard]

Some pictures

First is a conventional crankshaft for those who belive that a common crankvolume is OK.
For those who do not have true faith, I offer a compact mid bearing/seal solution shown in next two.


https://imgur.com/fk2c5Kh
https://imgur.com/qERR8Ec
https://imgur.com/kLlORzK

[Nath88]

I think have confirmed some ARC/HCCI operation of the injected YZ. I have a lean island on the fuel map, 15.5:1 AFR, centred around 8% throttle between 3300-5300rpm, in this area combustion goes from sporadic to very smooth and quiet, bike gains a little torque (accelerates a little), and the kill switch stops working. I can hold the kill switch as long as I like provided I don't move the throttle into the richer area. It doesn't 'feel' good though, the response is not linear when transitioning through the lean area, it feels like the engine is trying to run away. The throttle response is also pretty dull when it's running so lean.

[Flettner]

Niels, we are building a V twin using two of my cylinders but cylinder patterns modified somewhat. Its a rotary valve twin with variable housing/throttle technology, mark two TPI.
I'm building the crank with a center section having one bearing and a labyrinth seal. Connected via I believe what is called a Hirth coupling, I didn't know there was a name for this system, I just build a I see fit. This engine has been designed with a balance shaft of sorts. The big end pins are at 360 degrees but by making different crank centers can be what ever we want.

Cylinders are 350cc each.

[peewee]

Riding in sand requires a broad powerband and a close-ratio gearbox because the rpm-drops during upshifts are far greater than you would expect from just looking at the gear ratios.
With a spinning rear wheel your crankshaft may be doing 8000 rpm but your riding speed may only correspond to 4000 rpm.
During an upshift the spinning stops and after the upshift your crankshaft rpm wil have dropped well below 4000 rpm, where no-one is home, power-wise.
MX-practice is to grab the clutch and send enough torque to the rear wheel to get it spinning again. MX-sidecars with 800cc two-stroke singles are the worst:
some riders cover the whole track in third gear.

your right frits. to have any chance at success in sand racing, a close ratio gearbox is required and I would even like to try a super close ratio gear set as it may work better still. lets not forget the huge value of seemless up shifts as well. quick loss of speed and the massive rpm drops (where no one is home) could be all but avoided. its a shame such a gearbox would probly cost 4x more than my whole bike is even worth :laugh:. hey that reminds me, since the hot topic now days is emmisions and fuel consumption, wouldn't a seemless gearbox help somewhat in those categories ? it must have crossed ktm's mind a few times I would think. unless the engineering and manufacturing costs are far to high for a simple dirt/enduro bike

oh ya heres the ratios of my latest sand hill racer. incase your wondering, the exh opens at a measly 84* atdc :bleh:. three useable gears out of a total of five aint bad i suppose

15:33
16:24
18:21
20:19
27:21

[Grumph]

Niels, we are building a V twin using two of my cylinders but cylinder patterns modified somewhat. Its a rotary valve twin with variable housing/throttle technology, mark two TPI.
I'm building the crank with a center section having one bearing and a labyrinth seal. Connected via I believe what is called a Hirth coupling, I didn't know there was a name for this system, I just build a I see fit. This engine has been designed with a balance shaft of sorts. The big end pins are at 360 degrees but by making different crank centers can be what ever we want.

Cylinders are 350cc each.

Radial serrations and clamped up via a bolt through the center ? How'd you cut the radial teeth ?
Historically Hirth couplings have only been used where someone was prepared to pay a big bill....

[Niels Abildgaard]

Niels, we are building a V twin using two of my cylinders but cylinder patterns modified somewhat. Its a rotary valve twin with variable housing/throttle technology, mark two TPI.
I'm building the crank with a center section having one bearing and a labyrinth seal. Connected via I believe what is called a Hirth coupling, I didn't know there was a name for this system, I just build a I see fit. This engine has been designed with a balance shaft of sorts. The big end pins are at 360 degrees but by making different crank centers can be what ever we want.

Cylinders are 350cc each.

A picture of an Adler crank with Hirth coupling in center

http://www.motohistory.net/images/Twostroke14a.jpg

My proposal can maybe make a narrower enggine

[husaberg]

A picture of an Adler crank with Hirth coupling in center

http://www.motohistory.net/images/Twostroke14a.jpg

My proposal can maybe make a narrower enggine

This may interest you Niels

https://www.kiwibiker.co.nz/forums/album.php?albumid=4834

And this one
https://www.kiwibiker.co.nz/forums/album.php?albumid=4835

Plus as Frits mentioned the JBB
https://www.kiwibiker.co.nz/forums/album.php?albumid=4836
the Swissauto v4 was a hirth coupling.

There is a process that is used that fractures shafts used in production engines i am not sure how it differs or how it is done.

[Flettner]

Radial serrations and clamped up via a bolt through the center ? How'd you cut the radial teeth ?
Historically Hirth couplings have only been used where someone was prepared to pay a big bill....

Not that bad to build, I just used a tapered cutter in 4140 and some bearing blue. Machined the diameters oversize then once all fitted up, finish machine. I use a larger dia bearing in the middle so as to have plenty of contact area.
When finished I get everything nitrided.

Niels, I want a very ridgid crank, only one rod per set of crank webs and I want two separate crank cases. Weight is important but it must be robust enough to handle a hiding first.

[TZ350]

I think have confirmed some ARC/HCCI operation of the injected YZ. I have a lean island on the fuel map, 15.5:1 AFR, centred around 8% throttle between 3300-5300rpm, in this area combustion goes from sporadic to very smooth and quiet, bike gains a little torque (accelerates a little), and the kill switch stops working. I can hold the kill switch as long as I like provided I don't move the throttle into the richer area.

HCCI that is very interesting.

I got a "new to me" twin channel oscilloscope off Trademe today, the old one had died on one channel. So now I can see what is going on I am looking forward to having some time to get back to exploring the EFI 2T swapping maps issue.

[SwePatrick]

Reedpetals.. Has there been any more development to them?

I read somewhere on the web that someone has experimented with tapered petals.
Thinner at the end, and thicker at the base.
Say 0.5mm thick under the screws, and 0.3mm thick at the other end.
This to get high tension but low inertia.

Rgds
Patrick

[Frits Overmars]

Are there any classes for racing where a twincylinder two stroke is wellcome?Superkarts.


First is a conventional crankshaft for those who belive that a common crankvolume is OK.
For those who do not have true faith, I offer a compact mid bearing/seal solution shown in next two.I'm afraid faith and physics do not have much in common, Niels. In my experience engines are not very religious, but they obey unquestioningly to the laws of physics.

[WilDun]

Radial serrations and clamped up via a bolt through the center ? How'd you cut the radial teeth ?
Historically Hirth couplings have only been used where someone was prepared to pay a big bill....

Ariel decided to do a "cheapie" version of that centre coupling on their two stroke twins (ask TZ) and made theirs with a tapered shaft and woodruff key, as in ignition flywheels - It wreaked havoc with the ignition timing when it decided to move!
Don't think the Hirth arrangement would move (so long as the bolt remained tight).
Guess the "key" to machining the Hirth Coupling is as Flettner says, ie turning it to size and of course true, (after fitting up).

BTW does anyone know how the centre disc/common pin arrangement discussed before affects the flow into the transfer passages in a "V" engine?

[dtenney]

Superkarts.

I'm afraid faith and physics do not have much in common, Niels. In my experience engines are not very religious, but they obey unquestioningly to the laws of physics.

For Niels.......In addition to superkarts...check out outboard hydroplane race motors at www.grmracing.com. Plenty of 1, 2, 3 and 4 cylinder motors to look at.

[Frits Overmars]

does anyone know how the centre disc/common pin arrangement discussed before affects the flow into the transfer passages in a "V" engine?It shouldn't. Seen from the inside of the crankcase the left and right flywheels appear identical. You can't see from there if one flywheel is much narrower than the other.

[Flettner]

Anyone here know about Mikuni oil pumps, can the drive shaft run either way? I see inside they are just a worm drive and an adjustable cam. I think I remember the valves are just spring loaded balls. It's not a rotating drum with ports is it or something like that? I don't want to pull this unit I have here apart if I can help it. It's out of a KE 175, reed version. By chance someone may know.
I guess I could just test in in the lathe.

[Ocean1]

Anyone here know about Mickuni oil pumps, can the drive shaft run either way? I see inside they are just a worm drive and an adjustable cam. I think I remember the valves are just spring loaded balls. It's not a rotating drum with ports is it or something like that? I don't want to pull this unit I have here apart if I can help it. It's out of a KE 175, reed version. By chance someone may know.
I guess I could just test in in the lathe.

Not very helpful, but some of them have internal ports feeding the pump bearings from the pressure side, which changes with rotation...

DAMHIK.

[WilDun]

It shouldn't. Seen from the inside of the crankcase the left and right flywheels appear identical. You can't see from there if one flywheel is much narrower than the other.

Ah, I see what you mean, I need to brush up on my ability to properly picture things in my head!
Maybe I should do a wooden model in order to visualise how it would work or find out why it is necessary at all! ).


.......... Did that (with polystyrene), now it's pretty well sussed!.....:rolleyes:

[Flettner]

Not very helpful, but some of them have internal ports feeding the pump bearings from the pressure side, which changes with rotation...

DAMHIK.

I guess I might just have to pull it apart and see, bugger it. It has been years and years since I've had one apart and this little KE one looks a little different to the common Kawasaki / Suzuki units. This KE pump is very small and runs at crankshaft speed, direct coupling. The size and weight appeal to me just that where I want to use it the shaft turns opposite to it's original direction and my crank is also turning the opposite direction.

Google it! yes you are right, direction is important.

[husaberg]

I guess I might just have to pull it apart and see, bugger it. It has been years and years since I've had one apart and this little KE one looks a little different to the common Kawasaki / Suzuki units. This KE pump is very small and runs at crankshaft speed, direct coupling. The size and weight appeal to me just that where I want to use it the shaft turns opposite to it's original direction and my crank is also turning the opposite direction.

Google it! yes you are right, direction is important.
http://www.dansmc.com/2_stroke_oilpump.htm

bound to be a few Keihin MB5 ones laying about at my place
pretty sure they are direct but i have never had one appart.
333477333478333479

[Niels Abildgaard]

For Niels.......In addition to superkarts...check out outboard hydroplane race motors at www.grmracing.com. Plenty of 1, 2, 3 and 4 cylinder motors to look at.

Thank You for links.
Opposed cylinders and straigth pipes.
Looks wilder and more expensive than buckets.
I will try to get more information.
Are there other manufacturerers and a forum like KiwiBiker but for hydros somewhere?
My marvellous V2 crank will be more mass but flywheel and the drive train to screw much less.

[dtenney]

Thank You for links.
Opposed cylinders and straigth pipes.
Looks wilder and more expensive than buckets.
I will try to get more information.
Are there other manufacturerers and a forum like KiwiBiker but for hydros somewhere?
My marvellous V2 crank will be more mass but flywheel and the drive train to screw much less.

Carlo Verona at VRP is another manufacturer.

For more information on the racing in the USA go to: www.ustitleseries.net and www.hydroracer.net

There is not really a boat racing site anywhere near as good as Kiwibiker that I know of.......most of the serious motor junkies i race with are transfixed on this site and this thread.

[Grumph]

There is not really a boat racing site anywhere near as good as Kiwibiker that I know of.......most of the serious motor junkies i race with are transfixed on this site and this thread.

Seattle Smitty has already given us a link to the "Building a looper beast" thread from the Boatracing facts forum too.

[MotleyCrue]

Hoping someone may be able to help. I once saw a video maybe from this thread or maybe on YouTube where these guys were racing boats with like a half of an exhaust pipe. They had the big diverging part but thats it, no rear cone. Really loud. It was some sort of race series and I think it was the rule that the exhaust had to be like that, maybe in Indonesia or somewhere like that. The boats raced down a small river I think. Anybody know what I'm talking about? Link? I tried searching Google but must not be putting in the right keywords.

[Muciek]

Crazy Thai Drag Race Long-tail boat :laugh:
https://www.youtube.com/watch?v=9CPZ3svFfn0

[tjbw]

Hoping someone may be able to help. I once saw a video maybe from this thread or maybe on YouTube where these guys were racing boats with like a half of an exhaust pipe. They had the big diverging part but thats it, no rear cone. Really loud. It was some sort of race series and I think it was the rule that the exhaust had to be like that, maybe in Indonesia or somewhere like that. The boats raced down a small river I think. Anybody know what I'm talking about? Link? I tried searching Google but must not be putting in the right keywords.

Include Thai long tail boat in the search. Or just look at this posting by our friend Luk:

https://m.youtube.com/watch?v=Yp91Ml5mxg0

and read his description.

[Flettner]

I tried searching Google but must not be putting in the right keywords.
You probably just missed out the word CRAZY.

[dtenney]

You probably just missed out the word CRAZY.

The "half an exhaust pipe" is called a megaphone exhaust. This preceded the development of the tuned pipe. The correct length megaphone exhaust has some of the same effect as a tuned pipe...but with a much smaller effect than a tuned pipe. Tuned pipes made megaphone exhausts obsolete.

With megaphone pipes there is also a "small" issue with noise. A two stroke outboard with megaphone exhaust, running a blend of nitro and methanol, produces the most beautiful but ear wrenching sound ever. It can be heard for miles....that is not a positive in today's world.

[WilDun]

Tuned pipes made megaphone exhausts obsolete.
Tell them that (they won't hear you).


It can be heard for miles....that is not a positive in today's world.
These guys have turned everything we have learnt on safety and the two stroke motor on it's head - and we thought the IOM was madness!
I mean going at those crazy speeds facing backwards! :eek:

[teriks]

.. not to mention that razor sharp prop just waiting to cut you into pieces if you fall out of that.. thing.
Crazy fun though.

[TZ350]

333507

These are the ugly NSR heads with the offset plug that nobody seems to want. But they could be answer to my problem of how to get access to the combustion chamber to measure the combustion pressure so the EFI system knows if the motor has fired or not.

By a happy coincidence the pressure sensor neatly screws into the plug hole and the center of the combustion chamber has a cast in supported between it and the outside shell. It maybe enough to fit a 10mm central plug in. Two birds with one stone, pressure sensor and central spark plug.

Now to find another of these heads so I can cut it in half to see how much meat there is between the combustion chamber and outer head shell, enough for a 10mm plug I hope..... :)

[jbiplane]

3Kg will be possible.Close at least

And spare parts list

http://www.dle-engines.com/dleg0060.html

I will try and sketch a V-2 crankshaft plus bearing system using these parts.I have quite some already and they are cheap.
Are there any classes for racing where a twincylinder two stroke is wellcome?

Hi Niels. Unfortunatelly all chinese cheap stuff made of "plasticine". They use aluminum alloys with big% of scrap and Zn.
I have in my workshop 9 CNC machines (mills up to 5-axes, EDM, lathe-turning) and can produce something better. My engines MUST survive 300 hours on 75% throttle...
So I have to use DLC coatings on piston rings, add silver and vanadium to standard aluminum alloys...

[husaberg]

333507

These are the ugly NSR heads with the offset plug that nobody seems to want. But they could be answer to my problem of how to get access to the combustion chamber to measure the combustion pressure so the EFI system knows if the motor has fired or not.

By a happy coincidence the pressure sensor neatly screws into the plug hole and the center of the combustion chamber has a cast in supported between it and the outside shell. It maybe enough to fit a 10mm central plug in. Two birds with one stone, pressure sensor and central spark plug.

Now to find another of these heads so I can cut it in half to see how much meat there is between the combustion chamber and outer head shell, enough for a 10mm plug I hope..... :)

Rob there is pics of John Tice cutting one open on the thread i posted a few pages ago, when he converted Brens to center plug.
Don't ask what page

John Tice here (http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page9) and here (http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page19) here (http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page35) shows how to make the paterns for cast sleves, i believe he used to supply them for a few manufacturers.

okay this one

http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page46

http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page45

[TZ350]

.

Great, thanks Husa.

[Frits Overmars]

333507These are the ugly NSR heads with the offset plug that nobody seems to want. But they could be answer to my problem of how to get access to the combustion chamber to measure the combustion pressure so the EFI system knows if the motor has fired or not. By a happy coincidence the pressure sensor neatly screws into the plug hole... That must be the fattest pressure sensor I have ever seen. Why so big?


My engines MUST survive 300 hours on 75% throttle... So I have to use DLC coatings on piston rings...I have been talking to DLC-suppliers about the suitability of DLC-coating on piston rings for a couple of years, and each time they tell me that the maximum safe temperature for DLC has gone up a bit, but that it still is not enough for use on piston rings.
What exactly have you got coated Valery? The top and bottom faces of the rings or their circumference? And how is it holding up?

[speedboy]

Kistler have a special sensor for measurement (and they have very good torque flange)

I have a one, but only for inlet pressure.

https://www.kistler.com/en/applications/automotive-research-test/engine-research-development/combustion-analysis-cylinder-pressure-testing/

Very accurate, very fast, very small and very costly. :)

[jbiplane]

That must be the fattest pressure sensor I have ever seen. Why so big?

I have been talking to DLC-suppliers about the suitability of DLC-coating on piston rings for a couple of years, and each time they tell me that the maximum safe temperature for DLC has gone up a bit, but that it still is not enough for use on piston rings.
What exactly have you got coated Valery? The top and bottom faces of the rings or their circumference? And how is it holding up?

Hi Fritz
One local company made new composite molibdenum-DLC coating for free for us, circumference of 20 rings clamped together per time. Rings works with our in-house nikasil better than anything I tried before, but when I tried to order now price become irrational.
So now I want just buy 50, 54, 60 and 66mm rings which are good for nikasil.

Other question. In ex-soviet union produced some cast-irons with big % of Cr, Mo, Ni. They had hardness ~600Hb.
I know chemical compositions but cannot find foreighn analogs. The typical cast itons used for liners had ~350Hb.
Does anyone know best possible cast irons grades or steels which have hardness 600+ and were tested for racing applications?

[TZ350]

That must be the fattest pressure sensor I have ever seen. Why so big?

I am not sure why they are made that way. They look big on a 125 head but they seem pretty normal when they are fitted to the big high pressure natural gas compressors we have been involved with. There were a few left over at work. Different pressures from the different compressor stages, 60 - 125 - 315 and 400 bar, so a few different pressure ranges to chose from.

333508

Anyway we now know that there is not enough meat between the top of the combustion chamber and cylinder head cover to drill and tap for a 10mm spark plug. But there is for say a 2mm dia hole and if I weld a good bung on top of the head we could put the pressure sensor there. Leaves me with the ugly side plug but still good enough to prove the idea of measuring the combustion pressure for the EFI system.

[Flettner]

I have some 8mm, 9 heat range plugs if you want to try one.

[nitro2tfx]

I am not sure why they are made that way. They look big on a 125 head but they seem pretty normal when they are fitted to the big high pressure natural gas compressors we have been involved with. There were a few left over at work. Different pressures from the different compressor stages, 60 - 125 - 315 and 400 bar, so a few different pressure ranges to chose from.

333508

Anyway we now know that there is not enough meat between the top of the combustion chamber and cylinder head cover to drill and tap for a 10mm spark plug. But there is for say a 2mm dia hole and if I weld a good bung on top of the head we could put the pressure sensor there. Leaves me with the ugly side plug but still good enough to prove the idea of measuring the combustion pressure for the EFI system.

We've been using cylinder pressure sensors (way smaller than in your pic) since 1993 and selling full combustion pressure analysis systems for racing engines since 2001. Let me know what you are looking for and I will see if we have anything used. If we have anything used that'd be as cheap as you are going to get anything that is viable (actually built for what you are doing).

I gather you don't need any sort of full analysis system for the combustion pressure, nor high speed port/pipe pressure waves, transfer pressures etc., you were just looking to see the pressures at +/- locations around to TDC ?

[TZ350]

Hi Nitro2tfx. yes very interested in what you might have for measuring combustion pressure. Basically just need to be able to differentiate between a compression only event and a true combustion event. 12V supply voltage and for the Arduino mini PLC a 0-5V analog output would be the most useful but 0/4-20mA is easily converted by measure the voltage across a resistor on the output side I guess. PM with contact details has been sent. Thanks.

[TZ350]

I have some 8mm, 9 heat range plugs if you want to try one.

Thanks, but the support cast into the head is probably even to marginal for them.

My thinking about EFI has moved along a bit. We all know that direct cylinder injection after the exhaust port has closed is clean but a pretty limited rpm and performance option.

But maybe direct injection for low speed when there is a lot of time and off throttle operation when there is not much fuel demand and we want to avoid fuel being blown back out of the inlet or lost down the pipe.

By combining direct with "B" port injection for the high fuel demand on the pipe and full throttle maximum power situations where the motors trapping efficiency is highest might give the best of both worlds.

Combining the two approaches might give a real high performance and powerful motor that is also very clean.

[speedboy]

You can easy buy 8mm spark plug:
ngk Er9eh or er10eh

[TZ350]

.

Interesting read, EFI and Turbo 2T scooter:- http://www.apriliaforum.com/forums/showthread.php?185518-Gen-II-Port-Fuel-Injected-Turbocharged-Morini-build

Orbitals tec paper:- http://www.apriliaforum.com/techtips/sr50/orbital.pdf

[TZ350]

You can easy buy 8mm spark plug:
ngk Er9eh or er10eh

Good to know, will have a look to see what there is on Ebay.

[jasonu]

Hoping someone may be able to help. I once saw a video maybe from this thread or maybe on YouTube where these guys were racing boats with like a half of an exhaust pipe. They had the big diverging part but thats it, no rear cone. Really loud. It was some sort of race series and I think it was the rule that the exhaust had to be like that, maybe in Indonesia or somewhere like that. The boats raced down a small river I think. Anybody know what I'm talking about? Link? I tried searching Google but must not be putting in the right keywords.

Next time try being a bit more vague.....

[RAW]

A little read on HIPPING

http://www.dtic.mil/dtic/tr/fulltext/u2/a105562.pdf

[F5 Dave]

Is that a bit like Dogging? Not sure I want to click on that link:msn-wink:

[DaisyB]

Chaps, would appreciate a little help or pointers, the series I race in has fairly big problems with noise, the limit for us 2 strokes is 105db but most of us are about the 107 mark, I've tried all manner of different absorption silencers without being able to get it down much. It appears that next season the noise testers will stop being as "helpfull" as before. Any ideas on how to get the engines quieter without affecting performance? (air cooled geared engines for the most part, though the autos are as bad and are all watercooled) Thanks.

[1948rod]

Chaps, would appreciate a little help or pointers, the series I race in has fairly big problems with noise, the limit for us 2 strokes is 105db but most of us are about the 107 mark, I've tried all manner of different absorption silencers without being able to get it down much. It appears that next season the noise testers will stop being as "helpfull" as before. Any ideas on how to get the engines quieter without affecting performance? (air cooled geared engines for the most part, though the autos are as bad and are all watercooled) Thanks.

Intake noise plays a blg part of the overall noise. Karts losing an air box are black flagged for noise. A large amt. of noise comes from the thin walls of the chamber so wrapping the rear part would help and also keep the pipe warm. For a quick fix at the track try some silicone beads along the chamber and a couple of hose clamps around the chamber.

[wobbly]

An easy fix for noise is to shove the stinger up to the beginning of the rear cone.
Put the nozzle at the exit so its easy to change - then a short sleeve into a normal muffler.
This kills the high frequency racket that makes the dBA meter go spastic.

Air boxes as used by karts work great at killing noise - I built one that had 4 - 30mm intake tubes, all varying lengths.
In the 125 SKUSA CR125 engine this made around 1.5HP more ( in 40 ) than a normal pleated filter.

[jamathi]

An easy fix for noise is to shove the stinger up to the beginning of the rear cone.
Put the nozzle at the exit so its easy to change - then a short sleeve into a normal muffler.
This kills the high frequency racket that makes the dBA meter go spastic.

Air boxes as used by karts work great at killing noise - I built one that had 4 - 30mm intake tubes, all varying lengths.
In the 125 SKUSA CR125 engine this made around 1.5HP more ( in 40 ) than a normal pleated filter.

The nozzle on the end.
I tried that on the 50cc Garelli.
It worked quite well...
1983, why O why didn't I use it forever after that?

[lohring]

We did a lot of dyno testing on noise reduction for 26 cc engine powered RC race boats. We used an internal stinger as described above combined with stinger water injection from the cooling system outlet. The double can stinger muffler after the water injection made the engine quiet enough to hear water slapping the hull. I've used everything from Axe deodorant cans to energy and aluminum beer cans for the muffler shell. We got less than 80 Db measured on the shore as the boats passed. Unmuffled boats can register over 100 Db. Otherwise we always wore hearing protection during dyno testing since the engines registered 110 Db without muffling. Water injection is going to be a non starter on land vehicles, though.

Lohring Miller

333542

[Frits Overmars]

We did a lot of dyno testing on noise reduction for 26 cc engine powered RC race boats. We used an internal stinger as described above combined with stinger water injection from the cooling system outlet. The double can stinger muffler after the water injection made the engine quiet enough to hear water slapping the hull. I've used everything from Axe deodorant cans to energy and aluminum beer cans for the muffler shell. We got less than 80 Db measured on the shore as the boats passed. Unmuffled boats can register over 100 Db. Otherwise we always wore hearing protection during dyno testing since the engines registered 110 Db without muffling. Water injection is going to be a non starter on land vehicles, though. My knowledge of boats can accurately be described as non-existent, so this may be a dumb question:
why don't you put the stinger under water? You'd have less noise and a bit of thrust as well, wouldn't you?

[MotleyCrue]

Next time try being a bit more vague.....

:msn-wink: ....and yet several people knew exactly what I was thinking of............long tail boats. Not so easy to google when I didn't know what they were called. Thanks guys.

[guyhockley]

Radial serrations and clamped up via a bolt through the center ? How'd you cut the radial teeth ?
Historically Hirth couplings have only been used where someone was prepared to pay a big bill....

Think the original Hirth couplings had dual pitch bolt as well... Google isn't finding it so it may be the oldtimers kicking in!


Ariel decided to do a "cheapie" version of that centre coupling on their two stroke twins (ask TZ) and made theirs with a tapered shaft and woodruff key, as in ignition flywheels - It wreaked havoc with the ignition timing when it decided to move!
Don't think the Hirth arrangement would move (so long as the bolt remained tight).
Guess the "key" to machining the Hirth Coupling is as Flettner says, ie turning it to size and of course true, (after fitting up).

I had a (mechanically competent) mate who swore that his old Ariel was what we would now call Big Bang, pistons rising and falling together. He said it looked like it came from the factory like that.
There is an aftermarket 250 twin engine for Lambrettas that uses a conical join but with 4 "keys".
I was always a bit bemused by the Italian two stroke twins' crank joining method, this one's a Harley/Aermacchi but there were others with the same system, I think. Copying or all designed by the same (Dutch?)man?
There was a discussion on Michael Moore's MC-Chassis about Hirth couplings fairly recently.

[Ocean1]

I was always a bit bemused by the Italian two stroke twins' crank joining method, this one's a Harley/Aermacchi but there were others with the same system, I think. Copying or all designed by the same (Dutch?)man?

Known in most industries as a muff coupling. :yes:

Not just pre Itallian twin, it's pre motorcycle. Probably pre traction engine come to that...

[marsheng]

Put the nozzle at the exit so its easy to change

Hi Wobbly, not sure what you mean here ?

If the rear cone is curved to get around a frame, may be difficult to change the stinger options. This is if I'm getting you right.

[Grumph]

Think the original Hirth couplings had dual pitch bolt as well... Google isn't finding it so it may be the oldtimers kicking in!quote

NSU race twins of the 50's ? It rings a bell. Guzzi did an inline four around then too which I think used Hirth couplings on the crank.





I had a (mechanically competent) mate who swore that his old Ariel was what we would now call Big Bang, pistons rising and falling together. He said it looked like it came from the factory like that.quote

One of the works Suzuki TR750 riders (Aldana ?) is reputed to have downshifted so violently during Daytona practise that he turned the triple into a "tringle"




There is an aftermarket 250 twin engine for Lambrettas that uses a conical join but with 4 "keys".
I was always a bit bemused by the Italian two stroke twins' crank joining method, this one's a Harley/Aermacchi but there were others with the same system, I think. Copying or all designed by the same (Dutch?)man?
There was a discussion on Michael Moore's MC-Chassis about Hirth couplings fairly recently.

When Aermacchi copied the TR/TD Yamaha twins it was on the cheap...Yamaha uses a splined joint there...

[WilDun]

I had a (mechanically competent) mate who swore that his old Ariel was what we would now call Big Bang, pistons rising and falling together.

Talked to an old American guy from Nevada who sold Suzukis and when the first fast six speed Suzuki twins came out, (T20) they tried them in desert racing but used the arrangement you are discussing (pistons rising and falling together) and called them "Twingles".

[wobbly]

You dont change the internal stinger ( and this is easily bent to fit a curved rear cone - but does not need to be,as the gas pressure can be bled off from anywhere ).
I welded a clamp tube to the end of the rear cone, and this had slide in nozzles that determined the back pressure.
The clamp tube then had a slip on muffler after the nozzle.

[tjbw]

Talked to an old American guy from Nevada who sold Suzukis and when the first fast six speed Suzuki twins came out, (T20) they tried them in desert racing but used the arrangement you are discussing (pistons rising and falling together) and called them "Twingles".

Will, Twingle is also a name used for 'split single' a twin uniflow twostroke, with shared combustion chamber.

https://en.wikipedia.org/wiki/Split-single

[Niels Abildgaard]

Think the original Hirth couplings had dual pitch bolt as well... Google isn't finding it so it may be the oldtimers kicking in!



There was a discussion on Michael Moore's MC-Chassis about Hirth couplings fairly recently.


I have seen these Hirth 504 crankshaft parts
http://www.homemodelenginemachinist.com/showthread.php?t=14558&highlight=hirth&page=3http://

[lohring]

My knowledge of boats can accurately be described as non-existent, so this may be a dumb question:
why don't you put the stinger under water? You'd have less noise and a bit of thrust as well, wouldn't you?
That was tried at least once that I know of and worked well. Outboards have used this for a long time. However, silencing isn't very popular with racers. We like to hear the sound. Only when the neighbors call the police with noise complaints, as happened in one race I attended, is something done. Europeans have much stricter noise rules than in the US.

Lohring Miller

[Grumph]

That was tried at least once that I know of and worked well. Outboards have used this for a long time. However, silencing isn't very popular with racers. We like to hear the sound. Only when the neighbors call the police with noise complaints, as happened in one race I attended, is something done. Europeans have much stricter noise rules than in the US.

Lohring Miller

Don't outboards release the exhaust into the prop vortex ? I realise the actual plumbing for an inboard wouldn't be hard but wonder at how the external pressure variations as between boat stationary vs moving would affect starting and coming on the pipe.

Noise - I was at a bike race meeting here once where an activist neighbour got the PA shut down as it was over the noise limit at the boundary. The bikes were fine...The neighbour - a doctor - was trying to get the circuit closed down. Once it was generally realised just how much money the track brought into the small town, he lost patients quickly - and soon moved. His legacy though is the tightest noise control at any NZ circuit - and a PA you can hardly hear.

[WilDun]

I have seen these Hirth 504 crankshaft parts

Well the Hirth coupling seems to work ok and the differential (double pitch thread) is a good idea - it's all a lot of work to machine and construct and as Grumph says would no doubt expensive to make!
I've got to hand it to that guy who made the model flat four - he persevered ..... and not a casting in sight!
Only criticism I would make is that he was short sighted when he decided to build a four stroke! ;)

[Michael Moore]

IIRC Billy Uhl, Penton/ISDT rider, ran a 360 degree crank Suzuki T20/X6 in dirt track and/or hare scrambles in the Pacific NW in the early part of his career. It was converted by a dealer that sponsored him.

Gordon Jennings mentioned that he thought to try the internal stinger in the late 1960s/very early 1970s, and that he later discovered it " . . . was an idea also advanced by an obscure German researcher some several years earlier."

Hans Hintermeier sent me some photos of an adjustable cam he did for an XT500 Yamaha engine (he was making his own lobes too). He used a differential-thread bolt to pull things together. He also sent me a photo from a German magazine showing the Hirth coupling on an NSU Rennmax crankshaft. The crankshaft on the 1957 350GP Guzzi single (among other various Guzzis, some of which used the Hirth coupling) also used the differential threaded bolt to hold it together.

https://www.youtube.com/watch?v=-WacJOVzxmY

Is a video showing the machining of a Hirth coupling for a small crankshaft on a CNC mill.

https://www.youtube.com/watch?v=-JskW3UdZx0

is another machining video and shows photos of the Hirth coupling on an Adler and other crankshafts. The machining is done with a manual mill and dividing head. The dividing head is angled off the X axis of the mill to give the depth change between the ID/OD of the coupling.

cheers,
Michael

[guyhockley]

Another crank joining method - unsuccessful TZ350 experiment.

[WilDun]

IIRC Billy Uhl, Penton/ISDT rider, ran a 360 degree crank Suzuki T20/X6 in dirt track and/or hare scrambles in the Pacific NW in the early part of his career. It was converted by a dealer that sponsored him.

Gordon Jennings mentioned that he thought to try the internal stinger in the late 1960s/very early 1970s, and that he later discovered it " . . . was an idea also advanced by an obscure German researcher some several years earlier."

Hans Hintermeier sent me some photos
cheers,
Michael

Unfortunately even though it had high HP at the top, the T20 would have needed some modifications here and there to make it more suitable for the dirt!

I did pay attention to the tailpipe suggestion when I first read Jennings book but I don't think he had actually tried that (and didn't claim to have either) - just suggested it ...... I think a lot of people did try it though!

Great videos - thanks.:niceone:

[wobbly]

The internal stinger idea Jennings said not to make it start at 1/2 the fully developed rear cone length as it lost power.I never did check that though
and made them always starting at the end of the belly.
This coincided with finding out about Faths stinger nozzle, so it was easy to make an adapter that held the internal stinger, and as well as allowing slide in nozzles
allowed the overhung internal tube a much stronger weld onto ( further up ) the rear cone.

[marsheng]

The internal stinger idea Jennings said not to make it start at 1/2 the fully developed rear cone length as it lost power.I never did check that though
and made them always starting at the end of the belly.
This coincided with finding out about Faths stinger nozzle, so it was easy to make an adapter that held the internal stinger, and as well as allowing slide in nozzles
allowed the overhung internal tube a much stronger weld onto ( further up ) the rear cone.


I like the idea of 'free' quieting. I'll give it a try next pipe I make. I will annoy one of the flag marshals as he always loves the sound and smell of my bike.

[SwePatrick]

In short:

I had the stinger on the middle of the belly, bike ran 'ok', it was nice and silent.
But tests later on showed quite suprising results with the stinger on belly.

When i placed stinger at the end of the cone it suddenly became consistant.
Before the powercurves had their own rollercoasterride *lol*
Stingerdiam also needed to be larger when on belly.

Rgds.

[marsheng]

I've done some searching but nothing concrete on this so I thought I better ask the experts.

I've popped a crank seal on the Maico 2 days to go before I leave for the MPSC. I can only find a single spring Viton oil seal locally and the 'original' was a double. (I think the original was only a Nitrile one as well) Does the seal need to be double spring with the gearbox oil on one side and 2 stroke on the other ?

Will Nitrile survive 8500 RPM. The last one seems to have lasted 2 seasons.

Cheers Wallace.

[jasonu]

I've done some searching but nothing concrete on this so I thought I better ask the experts.

I've popped a crank seal on the Maico 2 days to go before I leave for the MPSC. I can only find a single spring Viton oil seal locally and the 'original' was a double. (I think the original was only a Nitrile one as well) Does the seal need to be double spring with the gearbox oil on one side and 2 stroke on the other ?

Will Nitrile survive 8500 RPM. The last one seems to have lasted 2 seasons.

Cheers Wallace.

Your choices are 1, take a risk and fit the 'suspect' seal or 2, stay at home. I know what I'd do.

[husaberg]

Your choices are 1, take a risk and fit the 'suspect' seal or 2, stay at home. I know what I'd do.
You voted Trump.
http://images.memes.com/meme/853361 (https://www.google.co.nz/url?sa=i&rct=j&q=&esrc=s&source=imgres&cd=&cad=rja&uact=8&ved=0ahUKEwizpeGVweDXAhVEfbwKHfofALQQjRwIBw&url=http%3A%2F%2Fpatterico.com%2F2016%2F08%2F31%2F donald-trump-to-meet-with-mexicos-president-today%2F&psig=AOvVaw0J4e6L2Ie93wvM0HClsyIV&ust=1511932379894697)

[Grumph]

I've done some searching but nothing concrete on this so I thought I better ask the experts.

I've popped a crank seal on the Maico 2 days to go before I leave for the MPSC. I can only find a single spring Viton oil seal locally and the 'original' was a double. (I think the original was only a Nitrile one as well) Does the seal need to be double spring with the gearbox oil on one side and 2 stroke on the other ?

Will Nitrile survive 8500 RPM. The last one seems to have lasted 2 seasons.

Cheers Wallace.

Take three single lip seals - afaik, your nights at levels aren't spoken for so you've got time to use one seal per day.....

[marsheng]

You voted Trump.


Classic !!!!

[husaberg]

Classic !!!!
What size are the seals Wallace? being German they will be metric, my bet is as there is only so many different metric bearings and shaft combos they will be shared by quite a few other Japanese bikes.

[marsheng]

What size are the seals Wallace?

52x32x7 or 8 or 9

I found a chap down the road who was rebuilding his Maico and had some seals. So I have borrowed these and will order from Socamaico in the US. However, an alternative will always be good to know.

Cheers Wallace..

[husaberg]

52x32x7 or 8 or 9

I found a chap down the road who was rebuilding his Maico and had some seals. So I have borrowed these and will order from Socamaico in the US. However, an alternative will always be good to know.

Cheers Wallace..
Doesn't match any bikes in the PRO X cattledog.
http://www.pro-x.com/wp-content/uploads/2017/01/2017_Tech_online.pdf


Talked to an old American guy from Nevada who sold Suzukis and when the first fast six speed Suzuki twins came out, (T20) they tried them in desert racing but used the arrangement you are discussing (pistons rising and falling together) and called them "Twingles".

i would say they did it that way for power delivery
Ossa doubled up 250-500cc desert racing twin had to configure the crank the same, but that was due to the cylinders being so wide apart being a aircooled 500cc two stroke that the width caused a massive rocking vibration, the doubled up 500cc Greeves was the same.
Yamahas RD350 and RD400 twins never had the issue as they used narrow poxy transfers.
Suzuki got around this on the Cobra/Titan by offesting the transfers so they overlapped.

[WilDun]

Will, Twingle is also a name used for 'split single' a twin uniflow twostroke, with shared combustion chamber.

https://en.wikipedia.org/wiki/Split-single

There have been quite a few examples of those tried in the past, mostly having a conrod with a link for the rear piston however, they didn't seem to be worth the effort -
I think maybe Puch had the most successful one but there was an experimental one somewhere with twin (tandem) geared cranks and the cylinders tilted towards each other (no doubt for a more compact CC but quite similar to the animation though) - eventually it just faded away (using the excuse that the head was porous!).

Maybe a good subject for ("oddball") - eh?

[Frits Overmars]

There was an experimental one somewhere with twin (tandem) geared cranks and the cylinders tilted towards each other (no doubt for a more compact CC but quite similar to the animation though) - eventually it just faded away (using the excuse that the head was porous!).They didn't need an excuse; the FIM provided one when it banned blowers in racing.

[Niels Abildgaard]

They didn't need an excuse; the FIM provided one when it banned blowers in racing.

Very interesting.It can be even better than present normal two strokers with a tuned exhaust instead of that blowerthing
The amount of air/petrol mixture for a given power will be less due to the long,long cylinder and exhaust temperature will be higher.
But the exhaust piston also gets much hotter.
Aint no free lunch.
It will also make a better air powerplant.
Gyros and ultraligth trikes has a single ca 1.8 meter prop directly behind pilot where incoming air is let us say disturbed.
It gives a very powerfull torque reaction variation when power changes.Two 1.25 meter counterturning props side by side will be more efficient,no torque and almost vibration free.

[WilDun]

They didn't need an excuse; the FIM provided one when it banned blowers in racing.

The one I was thinking of was obviously inspired by the one in the pictures, think it was in UK in the seventies - it didn't seem progress further than the prototype stage (probably had a more realistic bore/stroke ratio than the one in the pic!). There looks to be quite a bit of 'lag' on the inlet piston!
Peripheral speeds on those gears might have been a problem too!

[peewee]

52x32x7 or 8 or 9

I found a chap down the road who was rebuilding his Maico and had some seals. So I have borrowed these and will order from Socamaico in the US. However, an alternative will always be good to know.

Cheers Wallace..

your in luck mate. the ktm 550 and 440 dirt bikes from the mid 90's used a 52x32x7 crank seal on the water pump side (left hand side). you can look it up on any ktm parts fishe that goes back to '96 and earlier. 0760325272 part#. it is only a single spring seal but it does a fine job of keeping gear oil out of the crankhouse. ive had a few of these engines over the years and never once has one leaked . let me know if you cant get one. their $18usd and I could have it in 2days and ship it over, not sure how much extra that would cost however. https://ktmpartsonline.com/ktm-part-finder/#/s/KTM//0760325272/1/ http://www.ktmonlineparts.com.au/part/ktm/0760325272#contentArea

[Frits Overmars]

The one I was thinking of was obviously inspired by the one in the pictures, think it was in UK in the seventies - it didn't seem progress further than the prototype stage (probably had a more realistic bore/stroke ratio than the one in the pic!). There looks to be quite a bit of 'lag' on the inlet piston! Peripheral speeds on those gears might have been a problem too!Those split-single (and split-twin) double-piston engines were generally long-stroke jobs Will, even the all-conquering DKWs of that era. And the lag on the inlet piston is just that, although the designers preferred to talk about the lead of the exhaust piston: open the exhausts early in order to provide sufficient blowdown, and close them early in order to give the compresor a chance to supercharge the cylinder during the time that the exhausts are closed again and the transfers are still open.
This picture shows the crank angle phase difference in their last blown double-piston design: exhaust (left-side piston) closed, transfer (right-side piston) still open.
333583

In theory the early-closing exhaust should limit scavenging losses as well; in practice the scavenging pressure washed massive amounts of fuel right through the engine, helped by the suction of the ear-splitting megaphone exhaust pipes. You'll understand the peculiar size of those DKW petrol tanks, knowing that they consumed one litre every 5 kilometers.
333582

The peripheral speeds on those gears were no problem. The coupling gears on Rotax tandemtwins and Aprilia V-twins have a bigger diameter than their crankshafts,
plus they run at double the revs of those old split-singles.
333584

[WilDun]

i would say they did it that way for power delivery
Ossa doubled up 250-500cc desert racing twin had to configure the crank the same, but that was due to the cylinders being so wide apart being a aircooled 500cc two stroke that the width caused a massive rocking vibration,........Yamahas RD350 and RD400 twins never had the issue as they used narrow poxy transfers.
Suzuki got around this on the Cobra/Titan by offesting the transfers so they overlapped.

Yes, I used to wonder why Suzuki used that layout on the T500, but in hindsight it was good design. BTW I remember when it was first sold in the US it was advertised as being "The world's first 500cc Dual Stroke"!
333586

[Tbh37620]

This ran over a welded in central port bridge that had added boost ports down each side.


Wobbly, do you have any photos or info on this welded in bridge(Parent materials, filler metal, etc)? I have several cylinders I would like to weld bridges into to expand the width of the ports. Id imagine the H1 cylinder was a cast iron sleeve in aluminum casting?


Thanks,

[wobbly]

The cylinder we used was a TZ250G model as this had by far the most modern port/tunnel layout of any of Yamahas old version twins.
We used a 58 stroker crank from a Banshee and I balanced that to use 61.5mm H1 pistons ( top ring only ) to stay at the 350cc limit.
You will have to talk to the plater you will be using,each has a preference for the weld and filler plate material.
Here in NZ they want 6061 - but Millenium is different again.

[Tbh37620]

The cylinder we used was a TZ250G model as this had by far the most modern port/tunnel layout of any of Yamahas old version twins.
We used a 58 stroker crank from a Banshee and I balanced that to use 61.5mm H1 pistons ( top ring only ) to stay at the 350cc limit.
You will have to talk to the plater you will be using,each has a preference for the weld and filler plate material.
Here in NZ they want 6061 - but Millenium is different again.

Thank you for that info. Have you ever successfully welded an exhaust bridge into an aluminum cylinder with an iron sleeve? Maybe it couldn't even be done but figured I would ask. Thanks again

[F5 Dave]

One might be tempted to bore out the iron. Weld in super generous ally bridge and slide a accurate sleeve in place maybe of ally then grind sparingly allowing for relief on the bridge before and after plating it as still will be crappy heat transfer in a very hot position. You will be water cooling them of course . .

Never tried it but in same position on bucket I chose to bore triple port so cast in steel connected to ally as stock and allows for thicker bridge between ports.

Of course with skinny through hole retained barrels these ports can be difficult but some alternative engineering can sidestep the original constraints some of which have been posted before.

[Tbh37620]

One might be tempted to bore out the iron. Weld in super generous ally bridge and slide a accurate sleeve in place maybe of ally then grind sparingly allowing for relief on the bridge before and after plating it as still will be crappy heat transfer in a very hot position. You will be water cooling them of course . .

Never tried it but in same position on bucket I chose to bore triple port so cast in steel connected to ally as stock and allows for thicker bridge between ports.

Of course with skinny through hole retained barrels these ports can be difficult but some alternative engineering can sidestep the original constraints some of which have been posted before.

Thats a good point on heat build up on the bridge. The thing I was hoping to pull off was putting a bridge in some older air cooled cylinders (Aluminum casting with iron sleeve) on my vintage race bikes that are single ext port. Maybe weld in a hand fitted aluminum bridge piece, slightly relieve the bore surface and have the whole thing nikasil plated?

I know they make several bridged air cooled moped cylinders, but these are all aluminum units.

[Flettner]

Thats a good point on heat build up on the bridge. The thing I was hoping to pull off was putting a bridge in some older air cooled cylinders (Aluminum casting with iron sleeve) on my vintage race bikes that are single ext port. Maybe weld in a hand fitted aluminum bridge piece, slightly relieve the bore surface and have the whole thing nikasil plated?

I know they make several bridged air cooled moped cylinders, but these are all aluminum units.

Consider casting new cylinders with bridges.

[husaberg]

Yes, I used to wonder why Suzuki used that layout on the T500, but in hindsight it was good design. BTW I remember when it was first sold in the US it was advertised as being "The world's first 500cc Dual Stroke"!
333586
Alfred Scott might have beat them by 50 odd years to that one.

[Michael Moore]

Here's a photo of Jeff Henise's TZ350 cylinder with added bridge from his LSR project done with wobbly's guidance.

[wobbly]

I have done a couple of air cooled cylinders, that had iron liners.Welded in a bridge, honed the thing true then dropped in an alloy liner.
This makes it possible to fully weld the liner in around the top, and then down both sides of the bridge to get good heat transfer.
I also welded around the junction of the transfer ducts and the bore edge, ensuring that the liner stayed true.
Once the porting was done, it was then plated, still running many years later.

[TZ350]

Last Sundays 2017 40 lap and 2 hour race at Mt Wellington (run anti clock wise this year).

In the morning before racing started I went looking for the two strokes. There were very few this year.

333628

Scott had Team GPR's remarkable 2T Kawasaki based 125cc air cooled bike there. Scott is the man behind the Team GPR bikes.


More pictures of Team GPR's 125 2T build. The full GPR125 story can be found here as well as lots of great videos of Bucket racing:- http://www.kiwibiker.co.nz/forums/showthread.php/150352-Team-GPR/page134

333629

88 another 2T was the winning bike last year, and the hot favorite for this year.

333630

Sharn was there with her air cooled Suzuki GP125 that she had done all the porting on herself.

333631

There are always new and old faces at the 2 Hour, it was great to see Ollie and his mates back, I enjoyed chatting with them about their bikes.

In the 2 hour there was drama, carnage and a black flag or two.

333622

The gamest rider in the 2 hour probably had to be Jessie who fell off, got knocked off and once became the meat in the sandwich. every time he got up, the pit crew straightened the bike and he got out there again.

[TZ350]

2017 40 lapper and 2 hour - 2

333632

A trip around the pits found some interesting bikes like this old school Honda twin, these were dominant before the Suzuki FXR150's took over.

333633

There were plenty of clever ideas like this small light weight tank idea on a Suzuki FXR150.

333634

KTM150, with a pressure feed plain big end bearing these have big potential for development as they are not RPM limited by the big end bearing like the FXR and Honda engines are with their roller big ends.

333635

Honda CBR150, out of the box, un modified these engines are very competitive.

333636

Yamaha 150 engine powered special with home built chassis. It was the eventual 2 hour winner.

333638

Suzuki FXR150 engine in a GPR frame. Suzuki FXR's are by and way the most popular Bike for Buckets.

[TZ350]

2017 40 lapper and 2 hour - 3

333639

Team ESE's star rider did us proud and brought home a podium finish in the 40 Lap race.....

40 Lap placings were ... :first:David Millington, :second:Will Ford. :third:Sharn Steadman.

333640

The KTM out on the track during the 2 Hour, it eventually came in, in second place.

333641 333642

88 set the fastest Super Pole and fastest lap during the 2 Hour race but was struck down by bad luck.

There was a lot of full contact racing between the front runners and his exhaust was damaged in one of the collisions. The bike was black flagged for excessive noise and after attempts at a temporary repair had to eventually retire with a broken exhaust stinger.

333643

Regan fettling the KTM.

333644

Paul and Dylon getting the Yamaha 150 special ready.


2 Hour :first:Paul and :first:Dylan, :second:Regan and :second:Nick, :third:Hayden and :third: Alex.


More 2Hour photos:- https://amcc.org.nz/news/2017/11/29/auckland-bucket-2-hour

Mylaps: ttps://speedhive.mylaps.com/Events/1483131 (https://speedhive.mylaps.com/Events/1483131)

Photos from Paul Bryne: https://www.facebook.com/media/set/?set=oa.1931264600469136&type=3

More Bucket racing photos on Chris Cains Flicker page:- https://www.flickr.com/photos/sonscc/sets/with/72157652099920135

AMCC Bucket racing gallery:- https://amcc.org.nz/bucket-racing-gallery

[peewee]

if using a iron sleeve, be sure all welding is finished before the new sleeve is installed, if at all possible. I made the mistake of welding on a iron sleeve Honda cylinder and before I realized what happened, the cyl had pulled away from the sleeve which left a large gap. the cyl was useless after that unless I were to install a new sleeve. if a aluminum sleeve is used and welded in, then im sure you could weld at any time down the road with little risk of the cyl pulling away, although I wonder if it could still pull away in the center portion ? still, care should be taken as the sleeve bore diam can become distorted (especially the small bridges between transfer ports) and need rebored

[jasonu]

333631

There are always new faces at the 2 Hour, it was great to see Ollie and his mates back, I enjoyed chatting with them about their bikes.



Do you get a punch in the face if you beat them?

[jato]

Hypothetically... lets say your have two cr 125's - one runs the crank forwards and the other backwards. all necessary engineering details have been taken care of so the main difference remaining is the thrust side of the piston becomes the exhaust side and the reed valve now "looks" at the crank surface coming toward it...what (if any) differences in engine life and power would you expect?

[wobbly]

Many variables to take into account.
If the cylinder is reversed, the straighter pipe will make more power, maybe 1.5 Hp.
Jan did the test with a kart engine of reversing the rotation, and even with the crank shrouds in place the difference was again about 1.5Hp
in favour of the crank spinning away from the intake flow.
The thrust face makes no difference - I tested that on the BSL.
The TM kart engine has an area cut away opposite the intake that allows flow from the spinning crank to " escape " up under the piston and toward the transfer entry, this idea again made about a Hp.

[jato]

Thanks, wobbly . the surface of the crank is doing about 200 kph so i suspected there would be an effect... if the crank wheels were fully shrouded by the cases so the reeds didn't "see" the crank at all surely that would be a big help... the exhaust side of the bore likely wouldn't be as slippery for a piston thrust face as the inlet side but that might not have any noticeable effect - plenty of engines live like that.

[F5 Dave]

I did a few 2hrs. Great races. I mounted an air horn (pump up canister) one year. Scares the shit out of back markers and isn't in the rules.

[TZ350]

I did a few 2hrs. Great races. I mounted an air horn (pump up canister) one year. Scares the shit out of back markers.

:laugh: ............

[jasonu]

I saw this carb 'wing' as part of a listing for a 2002 CR250. Apparently it improves low end throttle response.

[wobbly]

We tested that carb blade on Grumpys TZ350 with 38mm long bell round slide Mikuni carbs.
It did increase the throttle response off slow hairpins where the tall TZ gearing forced the engine off the pipe.
But what worked even better was fitting plastic UFO inserts into the hollow under the slide.
With these the pilot was reduced from a 60 to a 35 ( way more idle signal ) and then it really jumped out of corners ( for a piston port that is ).
The insert needed modifying with a bigger hole around the emulsion tube shroud, to prevent fuel being dragged past the needle on zero throttle/high rpm
that caused mid corner roll on richness.

[husaberg]

We tested that carb blade on Grumpys TZ350 with 38mm long bell round slide Mikuni carbs.
It did increase the throttle response off slow hairpins where the tall TZ gearing forced the engine off the pipe.
But what worked even better was fitting plastic UFO inserts into the hollow under the slide.
With these the pilot was reduced from a 60 to a 35 ( way more idle signal ) and then it really jumped out of corners ( for a piston port that is ).
The insert needed modifying with a bigger hole around the emulsion tube shroud, to prevent fuel being dragged past the needle on zero throttle/high rpm
that caused mid corner roll on richness.

Cameron writes about that effect quite a few times, he says it is the reason flat slides were re-developed to decrease the underslide volume.
https://books.google.co.nz/books?id=J7tQp2LtsYIC&pg=PA55&lpg=PA55&dq=flat+slide+carbs+kevin+cameron&source=bl&ots=qfN2zrkpzu&sig=I4EoGVDa8ToGaeL4kZcbtbcJ2aE&hl=en&sa=X&ved=0ahUKEwjd3bWf3-7XAhVFupQKHSh0ASoQ6AEILjAB#v=onepage&q&f=false
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=327113&d=1482399423
yeah i know about the reed pooping open bit being wrong;)

[Flettner]

Aren't carburetors and all associated crap in the inlet just a restriction?
EFI is most certainly the future and I might add, rotary valve.:yes:

[wobbly]

A bit hard to find a way to be allowed to put efi and rotary valves on a Pre 82 Junior TZ350 Yamaha.

[Grumph]

A bit hard to find a way to be allowed to put efi and rotary valves on a Pre 82 Junior TZ350 Yamaha.

Neil's going to have to do a roadrace Bighorn...Still legal for F3 or whatever it's called now.
Have to run it on petrol though...

[husaberg]

Neil's going to have to do a roadrace Bighorn...Still legal for F3 or whatever it's called now.
Have to run it on petrol though...

If he did a Rotax/Can-Am big bore 350 it would be Bears legal on the Vodka.
But all his own home made engines are also bears legal

[Flettner]

And there she Is, what a bighorn should have evolved into.

[WilDun]

Aren't carburetors and all associated crap in the inlet just a restriction?
EFI is most certainly the future and I might add, rotary valve.:yes:

Are you still using a (restrictive) throttle slide on the Bighorn, or is the "throttling" being done (or ever likely to be)
on the new one, by variable inlet opening/closing timing on the rotary valve?

[Grumph]

And there she Is, what a bighorn should have evolved into.

I've always thought Kawasaki should have done a tandem twin double Bighorn for the tighter circuits used for the F750 Title.
Even got the obvious name - the Longhorn...

But yours is nice too....

[Flettner]

Yes Will, the 'throttling' is done by the rotary valve slides (gibbs), one for open and one for shut side. there will be just a bell mouth attached to the inlet you see. The two little tubes you see sticking out house small needle rollers that support the shafts that drive these gibbs. So when wide open, up on song, there is just a very short inlet with nothing in the way. I am considering having a hole on the other side of the crankcase that opens up like a 24 /7 reed principal. Not in this first engine though. Fits real nice in this frame and its now got a YZ250X wide ratio gearbox.
FMF fatty is in for the chop, rear exhaust with a mid chamber bleed to keep the pipe short (and quiet) enough.
I know this has all been shown a million times but for those that don't understand the sliding gibb principal, here is my Bighorn one.

[Flettner]

I've always thought Kawasaki should have done a tandem twin double Bighorn for the tighter circuits used for the F750 Title.
Even got the obvious name - the Longhorn...

But yours is nice too....

You and me both Grumph, but I think better will be the V twin that this project is the prototype for. Two times what ever this pans out into.
%#$%^& en Kawasaki they should not have dropped the rotary valve.

[speedpro]

Modern engine management makes things like rotary valves a good idea nowadays. Without the wizardry not so much. Think back to early buckets and all the bob weights and springs used to make variable dodads, or variable valves working against springs with tapered needles and interchangeable jets and variable spring preload. All replaced with a couple of look-up tables.

[Muciek]

Rotary valve TZ, and a lot of other "weird" stuff on this bike https://www.facebook.com/coeno.vanhouten/media_set?set=a.234897273237166.57723.100001506864 493&type=3

[Muhr]

Hello guys this I my first post!

I've followed this thread for a while and you guys seem to keep up with a lot of fun stuff.
I'm doing a small hobby project that is a bit out of my comfort zone (a rotary valve 100cc V-twin 90 °).
I was wondering if there is someone who has some heads up regarding twin rotary valve assembly?

best regards Johan

[teriks]

Hello guys this I my first post!

I've followed this thread for a while and you guys seem to keep up with a lot of fun stuff.
I'm doing a small hobby project that is a bit out of my comfort zone (a rotary valve 100cc V-twin 90 °).
I was wondering if there is someone who has some heads up regarding twin rotary valve assembly?

best regards Johan
Not twin related at all, but I recon you should turn those disk supporting ribs around.
333676

[Muhr]

Not twin related at all, but I recon you should turn those disk supporting ribs around.
333676




Don’t now why I did that makes no sense!:facepalm:Just the feedback I wanted.

Thanks Tetiks

[WilDun]

Yes Will, the 'throttling' is done by the rotary valve slides (gibbs), one for open and one for shut side. there will be just a bell mouth attached to the inlet you see. The two little tubes you see sticking out house small needle rollers that support the shafts that drive these gibbs. So when wide open, up on song, there is just a very short inlet with nothing in the way. I am considering having a hole on the other side of the crankcase that opens up like a 24 /7 reed principal.............

I think the sliding gib thing is very sensible (especially on both opening and closing), as is the proposed "part time full bore unthrottled inlet port" on the other side. - might be great for road racing! Eh GRUMPH!



I know this has all been shown a million times but for those that don't understand the sliding gibb principal, here is my Bighorn one.
Is it because (as I always maintain) that ESE goes too fast and all this good stuff just disappears into the great cauldron of fantastic but forgotten ideas - all lost forever in this (otherwise great) thread? - or is it because I'm just a plain dozey old bastard whose short term memory aint so good these days? :rolleyes:

[chrisc]

I took the RS50 out to Levels on the weekend for the Southern Classic and beat up some 250 4ts, 150 2ts and 150 4ts.
In race 2 I set the 4th fastest time of a grid of 35 bikes. Also got it up to 143km/hr with a wind break, ~136ish without. Pretty chuffed about... until I seized it at the fastest bit of the track and it put me in hospital with a bruised lung and coughing blood...

Well, your 50 is being well used Dave and even looked beautiful until we both ended up in the gravel.
http://www.grandprixmachine.com/blog/2017/12/4/rs50-racing-at-the-southern-classic

https://static1.squarespace.com/static/54f417b0e4b0ba5e061bdebd/t/5a248d178165f5067708d1f2/1512344932290/IMG_7856.jpg?format=1500w

[Grumph]

I think the sliding gib thing is very sensible (especially on both opening and closing), as is the proposed "part time full bore unthrottled inlet port" on the other side. - might be great for road racing! Eh GRUMPH!

Might not, too....See ChrisC's report here...

Actually as i'm pretty sure I've already posted elsewhere, you could buy a little cable operated inlet tract/valve for your 100cc rotary valve kart engine back in the 60's. Pull the trigger for a burst of speed to pass....sounds like the Fan Boost for formula E cars now.
I'm pretty certain that you pulled the trigger at your own risk...

Chris - missed you again, dammit. At least you'll be moving slow enough for me to catch up and meet you now.

[Flettner]

I took the RS50 out to Levels on the weekend for the Southern Classic and beat up some 250 4ts, 150 2ts and 150 4ts.
In race 2 I set the 4th fastest time of a grid of 35 bikes. Also got it up to 143km/hr with a wind break, ~136ish without. Pretty chuffed about... until I seized it at the fastest bit of the track and it put me in hospital with a bruised lung and coughing blood...

Well, your 50 is being well used Dave and even looked beautiful until we both ended up in the gravel.
http://www.grandprixmachine.com/blog/2017/12/4/rs50-racing-at-the-southern-classic

https://static1.squarespace.com/static/54f417b0e4b0ba5e061bdebd/t/5a248d178165f5067708d1f2/1512344932290/IMG_7856.jpg?format=1500w

I'll bet they hated you, nothing worse than being beaten by a 50!
You need to get well soon and teach them that lesson again.

[Grumph]

I'll bet they hated you, nothing worse than being beaten by a 50!

No - not that kind of crowd. But anyone beaten by the Gixxer Cup bike that was there would be spitting tacks....

[Frits Overmars]

Hello guys this I my first post.... I'm doing a small hobby project that is a bit out of my comfort zone (a rotary valve 100cc V-twin 90 °).
I was wondering if there is someone who has some heads up regarding twin rotary valve assembly?Welcome Johan. Your drawings are looking real nice. Why did you decide to build a 100 cc engine? Is there any form of competition you can use it in?
You may have seen the JBB-pictures I posted earlier, but in case you missed them, here they are once again.
If you wish to Google: JBB stands for Jean-Bertrand Bruneau, a French dentist with many original ideas about motorcycle chassis and engines.
333710 333711 333712

[F5 Dave]

Chris that is both good and bad to hear. Keep blowing into that machine with the floating balls and get those lungs sorted.
And go up a pilot size. Closed throttle is a swine on long tracks.

[Muhr]

Welcome Johan. Your drawings are looking real nice. Why did you decide to build a 100 cc engine? Is there any form of competition you can use it in?
You may have seen the JBB-pictures I posted earlier, but in case you missed them, here they are once again.
If you wish to Google: JBB stands for Jean-Bertrand Bruneau, a French dentist with many original ideas about motorcycle chassis and engines.
333710 333711 333712

Thanks for the pictures Frits
For several reasons one is that there is a 100cc class in drag racing here in Sweden. Another is that I'm lazy and I am working on a 50cc project to a friend so I can use some calculations from there.
After working with those little ones you cant stop being fascinated by how match you can beat them up. (It will be a variator engine)

[ken seeber]

Muhr, can't exactly work out if the crankcases are separate or shared from the pics (others will probably point out the obvious) and make me look a blind wanker) but unlike the 'Rotax shared disc valve, where there was some symmetry, in your case, there must be some sort of asymmetry to the disc valve cavity and that there will be some preferential leakage favouring/disfavouring one cylinder. Could be so minor to be nothing anyway. Those Wobsssss and Fritsssss can advise here.
Also the disc valve appears to have a huge stress raiser in a non functional area at its hub. Nothing a couple of mouse movements couldn't sort out :msn-wink:

Still, keep it going and look forward to seeing it converted to metal and noise.

[Muhr]

Muhr, can't exactly work out if the crankcases are separate or shared from the pics (others will probably point out the obvious) and make me look a blind wanker) but unlike the 'Rotax shared disc valve, where there was some symmetry, in your case, there must be some sort of asymmetry to the disc valve cavity and that there will be some preferential leakage favouring/disfavouring one cylinder. Could be so minor to be nothing anyway. Those Wobsssss and Fritsssss can advise here.
Also the disc valve appears to have a huge stress raiser in a non functional area at its hub. Nothing a couple of mouse movements couldn't sort out :msn-wink:

Still, keep it going and look forward to seeing it converted to metal and noise.

Yes, :yes:it's a divided crankcase

That's right, disk valve does not ned to look like that.
I'm curious if someone experienced a difference in terms of, getting of idle with a twin

[jasonu]

I took the RS50 out to Levels on the weekend for the Southern Classic and beat up some 250 4ts, 150 2ts and 150 4ts.
In race 2 I set the 4th fastest time of a grid of 35 bikes. Also got it up to 143km/hr with a wind break, ~136ish without. Pretty chuffed about... until I seized it at the fastest bit of the track and it put me in hospital with a bruised lung and coughing blood...

Well, your 50 is being well used Dave and even looked beautiful until we both ended up in the gravel.
http://www.grandprixmachine.com/blog/2017/12/4/rs50-racing-at-the-southern-classic

https://static1.squarespace.com/static/54f417b0e4b0ba5e061bdebd/t/5a248d178165f5067708d1f2/1512344932290/IMG_7856.jpg?format=1500w

I used to do the same thing at the old Taupo track on my 100 Bucket. (not the bruised lung part though).

[TZ350]

I took the RS50 out to Levels on the weekend for the Southern Classic and beat up some 250 4ts, 150 2ts and 150 4ts.

Well, your 50 is being well used Dave and even looked beautiful until we both ended up in the gravel.
http://www.grandprixmachine.com/blog/2017/12/4/rs50-racing-at-the-southern-classic

Chris, sorry to hear you have had a bit of a nasty off, get well soon. :doctor: best wishes from Team ESE for a speedy recovery.

[TZ350]

.

Following on from Nath88’s suggestions about the amount of air flowing through the motor that needs fuelling depends on whether the motor has fired and the pipe action has sucked air through or not.

I have been looking for ways to see if the engine has fired or not. And I like Clints idea that measuring the in cylinder pressure just before exhaust port opening would be a reliable way to tell if the motor has fired. I guess it t would not take a very sophisticated pressure sensor to do that. One would not need to know the real pressure, only that there is more pressure and a simple home made sensor using a piezoelectric disk from a hobby shop may be enough to do that.

The system would not have to be that clever, with the help of an Aduino mini all I would need to know is that between two consecutive ignition trigger pulses there was an in cylinder pressure rise of a predetermined magnitude or not.



Clint Gray - www.tfxengine.com (http://www.tfxengine.com/) sent me some comments by email that made sense to me and with Clint’s permission I can share them.

The equipment that we sell is for engine tuning via measuring cylinder pressure, port pressure waves etc. per degree of crank rotation. That might be overkill for what you need.

There are 2 ways that you could do it in the cylinder.

The first would be to use a true cylinder pressure sensor which is necessarily exposed to the whole cycle. This would involve drilling and tapping the head.

The second way to do it would be to install a pressure sensor part way down the cylinder wall. It would involve drilling a tiny hole roughly 0.75mm to 1mm diameter straight into the cylinder wall then mounting a sensor somewhat back from the hole external to the cylinder.

As an example, if you drilled the hole anywhere in the cylinder wall circumference so the piston ring exposed the hole to the pressure from about 70 ATDC through all the crank angles to 70 BTDC, all you would need is a low pressure sensor mounted say an inch behind that hole (i.e. the hole is a 1 inch long passageway feeding the sensor), then take your reading at 80 ATDC and 80 ABDC. So twice per revolution 180 degrees apart. There would be quite a difference in pressure if the engine fired, yet the peak pressure and average temp the sensor would be seeing would not be all that high.

We also have a sensor that will work in the cylinder wall like described but it is super-fast etc. For what you are doing, if you mounted a sensor as above, the sensor would not have to be super-fast, nor would it see high pressures, and average temps wouldn't be all that high considering its location and the part of the cycle it is seeing. Also the hole is a dead end hole so there is no significant flow in that hole, not like a hole that is open to the atmosphere. You might be able to find/use a much cheaper sensor if you go through the cylinder wall.

Further to what I wrote above, regarding a small hole in the cylinder wall. As I mentioned you could measure twice per revolution 80 ATDC and 80 ABDC, or even just once per revolution at 80 ATDC and use a threshold pressure value to determine if it fired or not.

However, it would be simpler to take a reading at 80 ATDC and 80 BTDC then compare the two pressure values per revolution. That way you don't need to have a threshold pressure value, just compare the two directly every revolution, and since the readings are not 180 degrees apart, they are 160 and 200 degrees apart, it would be easy to know which reading is the ATDC reading and which is the BTDC reading.

The fact that the sensor is slow, say a ms delay shouldn't matter either. It is still going to "see" the pressure at 70 ATDC it's just that it's going to be a little bit of time for the sensor to fully register what it sees.

You will be able to tell right away whether you need to delay the reading a full ms or much less than that, because when the hole is closed the pressure the sensor is seeing is only going to be crankcase pressure, so not much, and then when the hole is uncovered it will jump up very quickly, to say 150-200 psi. A slow sensor may take a full ms to fully register a pressure to the nth degree but it will probably register most of that pressure rise in much less time than a ms. Lets say 200 psi is applied instantaneously to your ms delay sensor, well it may only take 1/10th ms for the sensor to register 50-100 psi of that 200 psi and that would be plenty to tell you that it fired. If you go this route use a sensor good for 300 psi or a little better so it has a safety factor.

If you run a small tube that seals (need good contact for heat transfer) to the engine, and it runs between the cylinder wall hole and the sensor, then the actual sensor (which is likely sizeable) can sit outside the engine where it has space. You still want the sensor fairly close to the engine of course.

FYI we have several customers that drill their cylinder walls and install one of our threaded M5 sensors, so it is not uncommon. They don't do it for the reason you are doing it for, they do it to more accurately measure cylinder pressures during the low pressure portions of the cycle. A low pressure sensor is used instead of a combustion sensor.

I think that you can still put a hole in at 70 ATDC and get a cheap and "slow" sensor to work. The average temperature from 70 ATDC to 70 BTDC is not going to be very high, and it's a dead end hole so not much flow.

With your 1/4"BSPT thread try to sleeve the inside hole of the sensor so that there is as little volume inside there as possible, without contacting the diaphragm in the sensor of course.
You want to have as little transfer of gases as possible moving to and fro, makes for less heat and a quicker fill (reading).

Clint.

[Muhr]

Welcome Johan. Your drawings are looking real nice. Why did you decide to build a 100 cc engine? Is there any form of competition you can use it in?
You may have seen the JBB-pictures I posted earlier, but in case you missed them, here they are once again.
If you wish to Google: JBB stands for Jean-Bertrand Bruneau, a French dentist with many original ideas about motorcycle chassis and engines.
333710 333711 333712

I have experienced that small rotary fed engines are very sensitive to the intake area crankcase volume and pipe area. Have you experienced any difference in a v-twin? Are they more forgiving in terms of time area?

[guyhockley]

Chris, sorry to hear you have had a bit of a nasty off, get well soon. :doctor: best wishes from Team ESE for a speedy recovery.

Same from me.

[Frits Overmars]

I have experienced that small rotary fed engines are very sensitive to the intake area crankcase volume and pipe area. Have you experienced any difference in a v-twin? Are they more forgiving in terms of time area?When it comes to gas dynamics and thermodynamics, I tend to treat any twin as two singles; in my experience all gas exchange processes in a twin are identical to those in a single. Engines with 1-in-2 inlet systems (Trabant) and 2-in-1 exhaust systems (BRP-Rotax) excluded of course.
333721 333722 333720

By the way: that Rotax engine could be shoehorned into a Trabant without much effort. Imagine standing at the traffic lights with your little two-stroke car merrily bubbling away, nobody having a clue that instead of 26 HP you now have 165 HP under your right foot :D.

[Frits Overmars]

Following on from Nath88’s suggestions about the amount of air flowing through the motor that needs fuelling depends on whether the motor has fired and the pipe action has sucked air through or not.Excellent lecture from Clint Gray, combining theoretical knowledge and practical thinking. I especially like the simple asymmetrical signal spacing.
Here is some more injection lecture for the Christmas holidays:

EDIT: uploading failed because the file is too big (2793 kB). You might try to find it yourself on the internet.
Search for WO2016193902A2 : Internal combustion engine having two fuel injectors per cylinder and control method therefor.

[SwePatrick]

'It' has been done....

http://teknikensvarld.se/provkorning-av-saab-96-zrt-800-173151/
https://www.youtube.com/watch?v=uxTG1tCMAtc

Still not fast thou :(

[ken seeber]

Excellent lecture from Clint Gray, combining theoretical knowledge and practical thinking. I especially like the simple asymmetrical signal spacing.


Gotta agree with Frits on this one (& others of course :sweatdrop).

[Muhr]

When it comes to gas dynamics and thermodynamics, I tend to treat any twin as two singles; in my experience all gas exchange processes in a twin are identical to those in a single. Engines with 1-in-2 inlet systems (Trabant) and 2-in-1 exhaust systems (BRP-Rotax) excluded of course.
333721 333722 333720

By the way: that Rotax engine could be shoehorned into a Trabant without much effort. Imagine standing at the traffic lights with your little two-stroke car merrily bubbling away, nobody having a clue that instead of 26 HP you now have 165 HP under your right foot :D.

I had my suspicion that it is the case.
When you have gone too far and standing on idle and not coming from it feel so close yet so far away. My hope is, however, that cylinder "A" will be a little more forgiving then cylinder "B" probably will be.:scratch:

Rotax engine in a Trabant that would be awesome. Have seen videos on smart cars with Hayabusa engines.:laugh:

[Nath88]

Excellent lecture from Clint Gray, combining theoretical knowledge and practical thinking. I especially like the simple asymmetrical signal spacing.
Here is some more injection lecture for the Christmas holidays:

EDIT: uploading failed because the file is too big (2793 kB). You might try to find it yourself on the internet.
Search for WO2016193902A2 : Internal combustion engine having two fuel injectors per cylinder and control method therefor.

I believe this is the same patent.
http://www.freepatentsonline.com/20170159598.pdf

Update on my thing:
-I'm overdriving the piezo transducer, they're rated at 15V AC, I'm seeing an output of 50V. The signal diminishes over time, quickly at first, then it settles. Could market it as 'self calibrating', but the better option would be to use a smaller disk to reduce the output.
-The signal to noise ratio is still not that great, and I'm hampered by being fixed to 1 value where the fuel table switch occurs. The ideal switch value varies by RPM.
333724
-I have found that the pipe effect on overall air flow is greater when the throttle is more closed, it's about 2.5x 8000rpm 100% throttle, and about 4x at 0% throttle (by extrapolation). I guess the pipe is providing a bit more intake vacuum, overcoming some of the throttle restriction.
-Richening the air fuel ratio to approx 14.4:1 from 15:1 has stopped the unwanted ARC/HCCI operation at light throttle.
-The next trial will be to use a differential pressure sensor between the intake and the crankcase. I've previously found crankcase vacuum increases with pipe effect, but it's relative to the total pressure in the system, which is influenced by atmospheric pressure and throttle restriction. Accounting for both with differential pressure might give me a usable signal. KTM must be doing something like this, since they are measuring crankcase vacuum.

[Flettner]

I see your water cooled exhaust spigot And raise you.
An ethanol cooled exhaust flange��
Athough it wasn't to cool the exhaust, It was to heat the ethanol. Wrong, don't need to do That.
It did heat the tank up, using the original mechanical injection system I used on the Kawasaki, with a circiting mechanical fuel pump.

[F5 Dave]

Neil I do love your inquisitive mind.
Wish I could get enough sleep to achieve 1/4 what you do.

[TZ350]

I see your water cooled exhaust spigot And raise you.
An ethanol cooled exhaust flange��It did heat the tank up.

Proof it was cooling the gas in the header, very interesting that.... :yes:

[TZ350]

.
Modified 1978 Suzuki GP100, water cooled, 6 speed, dry sump gearbox, 8 plate clutch and fuel injected. Target is 32 rwhp at 12250 rpm.

333771

The next step in the EFI saga is to detect with a piezoelectric sensor any in cylinder pressure just before exhaust port opening to see if the motor has fired or not.

333770

It was suggested to me that to get a good reading all I would need is a 0.75mm hole in the cylinder wall.

333769

The cylinder casting is very precise, no wasted metal anywhere so it is quite a challenge to find somewhere to drill through without breaking out into the water jacket. It wouldn't do having combustion gases escaping into the cooling water, it would boil up in no time.

333768

I managed to drill a clean 1.53mm hole through the cylinder with no break outs into the water jacket or cylinder head stud hole and the drilled hole came out just above the exhaust port. 1.53 and 1.55mm drills are much easier to work with than a 0.75mm one.

I made this quill with a 1.55 OD, 0.75mm ID tube and to be doubly safe the hole in the cylinder is drilled size for size with the last 5mm of the quill a 0.02mm interference fit in the cylinder wall so the quill is completely sealed in the cylinder at both ends. The quill was a grantee against breaking into the water jacket or a thin or porous patch of casting.

I was finding it challenging figuring out how to get a 0.75mm hole through the cylinder wall that would be reliably leak proof, and I am pretty happy with the way this has worked out.

[chrisc]

I 4 corner seized it. Pretty certain I overheated it which is unsurprising. 26 degrees by 9am, 32 degrees in the shade mid day. Undermaintained cooling system and no temp gauge :nono::weird:

https://static1.squarespace.com/static/54f417b0e4b0ba5e061bdebd/t/5a2ae8c9e4966b501214dbcc/1512761657868/IMG_8056.jpg?format=500whttps://static1.squarespace.com/static/54f417b0e4b0ba5e061bdebd/t/5a2ae9418165f53265d7edce/1512761693981/IMG_8058.jpg?format=500w


Chris, sorry to hear you have had a bit of a nasty off, get well soon. :doctor: best wishes from Team ESE for a speedy recovery.

Thanks team. Pretty bloody achy still but progressing well. Should be all good and have medical clearance for the nationals. I'm so hyped. I keep waking up at odd hours with racing and bike setup on the mind.


Chris that is both good and bad to hear. Keep blowing into that machine with the floating balls and get those lungs sorted.
And go up a pilot size. Closed throttle is a swine on long tracks.

You're soooo right Dave. I stuffed up not being proactive with setup.


I'll bet they hated you, nothing worse than being beaten by a 50!
You need to get well soon and teach them that lesson again.

So many laughs in the pits. "Is that REALLY a 50?!" Can't wait man.


Chris - missed you again, dammit. At least you'll be moving slow enough for me to catch up and meet you now.

Next racing I'll be doing is round 1 of the nationals, first weekend of Jan at Ruapuna. We'll have a massive field of 125s with our our grid this year and some really solid competition. Come say hey if you're around.

[F5 Dave]

I had about 3 of those Daytona ones. All failed pretty quickly so gave up as it was always pretty stable. . . At least on the last RG engine.

[Flettner]

My metal un printer at work. This is the real valve cover, the other was just a ' test cut'

[DoldGuy]

Stock Rod 125mm, currently running a 133mm Rod with a spacer plate. Wobbly posted the need to run much leaner jetting (I believe 145 from 165), trying to understand the reasoning behind this, I have never had to go this lean before & ran out of jets before getting close, was concerned about that lean of jetting, but after searching here, hoping this could be normal. Again trying to understand the why part? :psst:


Doldguy

[TZ350]

Stock Rod 125mm, currently running a 133mm Rod with a spacer plate. Wobbly posted the need to run much leaner jetting (I believe 145 from 165), trying to understand the reasoning behind this, normal. Again trying to understand the why part? :psst:Doldguy

I would love to know too, and used this search term "" long rod site:https://www.kiwibiker.co.nz/forums/showthread.php/ ''" to turn up a whole lot of references to long rods on the ESE thread. I then got distracted reading something else that was interesting.

Enter all of this in Google to find references to long rods on the ESE thread :-

long rod site:https://www.kiwibiker.co.nz/forums/showthread.php/

[Peter1962]

I would love to know too, and used this search term "" long rod site:https://www.kiwibiker.co.nz/forums/showthread.php/ ''" to turn up a whole lot of references to long rods on the ESE thread. I then got distracted reading something else that was interesting.

Enter all of this in Google to find references to long rods on the ESE thread :-

long rod site:https://www.kiwibiker.co.nz/forums/showthread.php/

I think that the link is not correct... this just shows up the start of the ESE thread ?

[Frits Overmars]

long rod site:https://www.kiwibiker.co.nz/forums/showthread.php/
I think that the link is not correct... this just shows up the start of the ESE thread ?So it wasn't just me; I think you're right Peter.

[F5 Dave]

Maybe he's drawing a long bow?

[TZ350]

333788

long rod site:https://www.kiwibiker.co.nz/forums/showthread.php/ ... worked for me ... :scratch:




Frits, many many thanks for a great artical ( and the previous 300 odd posts)

I have learned more in the last year reading posts from you, Wobbly and others than I have in the previous 50 years of 'playing' with two strokes.

I do not have much to offer to the discussion (apart from more questions!) but some may find this useful. Rather than use the site search which usually fails, use Google so to search this site use an ordinary search phrase and after it add

site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz/)

for example

Frits priceless site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz/)
or
Frits pisa site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz/)

the same will work for other sites with the appropriate site address

Mick

[DoldGuy]

Long rods that affect the case volume then influence the carb tuning dramatically as well.
I did a Rotax 257 single years ago for sprint kart racing, filling the crank webs with that UHWMP stuff.
This raised the case com form down near 1.3 up to about 1.35.
It needed complete rejetting and the main dropped from a 185 to a 165 due to the much stronger signal across the jets.
Going the other way on a 250 tandem twin by fitting long ( 120 ) rods and making full circle ( no pockets ) cranks, the jets then need to be huge
in size by comparison.
Honda used the short rod for years in the customer engines, but when push came to shove the final version used to win the last 250GP title used a long rod, for a reason obviously.
The big reed boxes that design had from day one, gave a relatively big case volume by default.

In my experience if a case reed is done as well as it can be ( look at a TM - KZ10 ) then there is very little difference in power if a cylinder reed
is also done properly with plenty of intake STA via piston cutouts and big Boyesens or floor ports.
The only real difference is that the boost port duct does not have a proper inner wall, and thus the flow regime is not as well controlled.

I finally found it...I had it backwards :facepalm:, requires richer jetting with the longer rod.

[DoldGuy]

Page 1370 ....












If you are looking for 2T tuning technical information I have found this thread is best read backwards, ie start at the last page and read back towards the beginning.





There are also over 7000 images on this thread, use "Thread Tools" to view them and then click through to the original post about them.





A lot of the decade pages have collections of quotes and links to other interesting things.


Page 1250 Links List
Page 1240 2T development Software, Port Theory, Interesting Sites
Page 1230 Compression Ratio, Ex duct shape and length, Fancy spark plugs.
Page 1220 Reed Valve Petals, Oxygen Sensors, Exhaust duct step at the pipe flange.
Page 1210 Ignition Trigger Woes, EngMod 2T and Blow-Down, Fuelling Curve.
Page 1200 Frits on power spread and the ratio of the maximum and minimum points in the power band.
Page 1190 No data, but a lot of talk about what the Ryger engine might look like.
Page 1180 Frits on 2T fuel consumption. M50 cylinder portmap and EngMod2T analysis.
Page 1170 Engine/Gearbox oils and bearings. Transfer duct shape and optimal Ex port timing.
Page 1160 Frits - Engines need large crankcase volumes, Power vis Handling.
Page 1150 Serious talk about crankcase volume.
Page 1140 Measuring the transfer duct length, Ignitec, Expansion chamber design, Trombone pipe.
Page 1130 Team GPR Edgecumbe Videos …. Cooling 2T’s …. 3xEx vis T port,
Page 1120 Crank Balancing, Ceramic Coating, Plugs, Piston Edge chamfers, RS125 pipe dimensions.
Page 1110 TeeZees progress on the EFI thing with the Beast.
Page 1100 No Data but some talk about pickups and EngMod 2T transducer position in the pipe.
Page 1090 Links about the Detonation Sensor and Temperature Data Logger.
Page 1080 No Data, the plenum is protested, Frits on Blowdown and Transfer window height.
Page 1070 Exhaust Duct shape, Kawasaki and BRC EFI dyno videos.
Page 1060 No Data but talk about Port shape and Flow in a duct on this page.
Page 1050 EngMod2T setup talk about pipes, transfer ports and the TubMax graph.
Page 1040 Basics of pipe design and how to influence where the point of maximum depression occurs.
Page 1030 Racing at Greymouth, its well worth a look to see Team GPR in action.
Page 1020 Pipe dimensions, Seattle Smittys hydroplanes. Husaburgs piston link.
Page 1010 Suspension Tuning.


Page 1000 has a lot of useful information and links. http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1000?p=1130773139#post1130773139








On Page 500, Bucket has links to how Team ESE built their 26, 28 and 31 hp engines:- http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page500

TZ350

This page is what led me to LOTS of reading & Wobblys Post....

My search results have been miserable here & using google, I will try the way you posted next.

Thanks for the help!

[DoldGuy]

I first tried it on a 50 cc in 1074: more power.
Going from 80 to 85
Then at Aprilia in 1996: more power.
Without varying the crankcase volume.
We went from 112 to 113 and 115, later 118 was tried, still better.
For the RSA we had to lengthen the connecting rod from 115 to 120 to improve inlet flow: more power.
It is mainly due to piston friction I think.
NSU already found this in 1953, piston friction was the main source of friction in their 250 4-stroke engine.
It may be different for a reed valve engine, I have not much experience with these.
But the piston friction loss will, of course, be the same in a reed valve engine.

Of course at BDC there is no difference as you have to adjust the cylinder height!
Maybe it is interesting that with a longer connecting rod I could use higher transfer ports on my 50.
Getting still more power!

The crankcase volume also changes, of course, unless you change the position of the piston pin in the piston, as we did at Aprilia
This can be better or worse....
You can change your crankcase volume in many ways.
But always keep in mind that flow is more important than volume.....
On rotary valve engines I found the bigger the better, within reason of course....
The Aprilia engines had very narrow crank wheels, (16mm) so a very big crankcase volume. About 660cc in TDC
A big crankcase volume makes very long inlet timings necessary.
And big carburetors.

This is probably the reason why reed-valve engines need a smaller crankcase volume.
The reeds 'decide' for themselves when to open...
They need some depression.
And because maximum inlet flow is probably determined by the reed block, big carburetors won't work on a reed-valve engine.
They just slow down the flow in the carburetor, making for a difficult carburetor adjustment.

So I think that a rotary valve engine will always give about 3-4 HP more (125cc) than a reed valve engine.
Because of its unrestricted inlet flow and less pumping losses.

If the longer rod has consistently yielded more power, why have some manufacturers gone to shorter rods?

KTM used to use a 132 Rod with a 29.7 compression height piston, then a 129 Rod & now a 125 with a 38 compression height. I would think case volume (and cylinder height) would be the same on these motors based on these numbers. What would be positive about the shorter rod length?

[JanBros]

this search term "" long rod site:https://www.kiwibiker.co.nz/forums/showthread.php/ ''"


I think that the link is not correct... this just shows up the start of the ESE thread ?

you are not supposed to click on the link, you have to copy everything between "" ..... "" and paste that in google. that way google searches the term long rod only on Kiwibiker.

if you want to search something else, you simply change long rod in exhaust duct for exapmle, so you paste exhaust duct site:https://www.kiwibiker.co.nz/forums/showthread.php/ in google (everything that's underlined)

[TZ350]

you are not supposed to click on the link, you have to copy everything between "" ..... "" and paste that in google.

That way google searches only on Kiwibiker.
"" exhaust duct site:https://www.kiwibiker.co.nz/ (https://www.kiwibiker.co.nz/forums/showthread.php/) "".... :Punk: sure makes finding stuff on the ESE thread a breeze.

[wobbly]

The only thing to add re case volume is that a reed engine does not respond well at all to " going bigger " than around 1.3 ratio.
The bigger volume does have a positive effect, just as it does in a RV, but this is badly offset by the change in Helmholtz frequency,that then affects the reed
petals 1st natural resonance.
This requires thinner and thinner petals, to get the resonance working again correctly, and these thin petals ( or less backup pressure ) causes them to go spastic.
They hit the stops and rebound, or simply wave about all over the place with no control, and this creates havoc with power - on the dyno as well as in the sim.
You can see this happening in the sim, with huge differences in the reed lift profile, from iteration to iteration, and overall power drops.
This is why its very difficult to model reed stiffness correctly,you must "guess " the main petal thickness to take into account the backups stiffness/effectiveness.

[Vannik]

you are not supposed to click on the link, you have to copy everything between "" ..... "" and paste that in google. that way google searches the term long rod only on Kiwibiker.

I am constantly surprised to see how few people know about Google Advanced Search https://www.google.com/advanced_search which does it all for you.

[F5 Dave]

What is this bedevilry?!

[husaberg]

"" exhaust duct site:https://www.kiwibiker.co.nz/ (https://www.kiwibiker.co.nz/forums/showthread.php/) "".... :Punk: sure makes finding stuff on the ESE thread a breeze.
I used KB thread search , advanced option, single content and came up with these. for "Long rod" and Mr wobbly.
it took 1/2 second.............
make sure if you are looking for a particuilar phrase to include "" marks...
Otherwise you will find Mr wob uses the word long a rather lot of times.....

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130990445#post1130990445
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130990569#post1130990569
https://www.kiwibiker.co.nz/forums/showthread.php/155907-ESE-s-works-engine-tuner?p=1130481748#post1130481748
https://www.kiwibiker.co.nz/forums/showthread.php/155907-ESE-s-works-engine-tuner?p=1130481699#post1130481699

But using different terms in regards to case volume and jetting gives this which is i assume what he was wanting
https://www.kiwibiker.co.nz/forums/showthread.php/155907-ESE-s-works-engine-tuner?p=1130478507#post1130478507


If you look at CCR in the context of what is accepted as being "normal", then the full range is generally accepted as being a low CCR at 1.3 and a very high CCR at 1.4.
This means a difference of 0.1 from "big" to "small", and the 50cc change in the case, represents 1/2 of the engines swept displacement by the piston in a 100cc bucket..
Aprilias latest engines are in the high 1.2s - and a very fast NZ champ 50 quad I built had 1.42, both on the very outer limits.
Changing from 1.4 to 1.3 would need huge jetting changes, like 4 mains, and this then affects the bsfc, and the pumping efficiency,needing a whole new approach to the transfer designs as well.
It goes on and on.
When you consider what happens when you change say the primary com from 13:1 up to 16:1,then this shows the relativity of the difference created.
But again - even the primary com change has huge effects that are not directly related to the numbers.
16:1 would need Avgas to stop deto obviously and this com would give great jump of the turns but would stop any pipe design from overeving.
Thus a high com engine needs a short pipe, or lots of retard, due to all the heat of combustion being released into the piston and the water - not the exhaust, making it appear longer to the engine. etc etc.
Change one element of a 2T and you are then looking at a whole raft of changes needed to optimise that setup,and it will never "work" if just one other element isnt synergistic with the rest.
And remember a general comment I made a while ago, about crap transfer ducting "liking" higher CCR ratios.

[peewee]

If the longer rod has consistently yielded more power, why have some manufacturers gone to shorter rods?

KTM used to use a 132 Rod with a 29.7 compression height piston, then a 129 Rod & now a 125 with a 38 compression height. I would think case volume (and cylinder height) would be the same on these motors based on these numbers. What would be positive about the shorter rod length?

have you ever tried to ride a 60hp dirtbike around a motox track ? i really doubt even the top pro riders had that much power. the japanese and ktm have been perfectly content for many years with about 45hp, which is quit a bit, considering the new bikes are barely 210lb. the main focus is not at all about power, but rather further development in chassis, suspension and weight loss.

how all the manufacturrs ended up at 66x72 with 125mm rods is a mystery to me. maybe it lends itself well to good packaging and handling.

think about this. for a common 250 dirtbike engine to reach 2.2 rod ratio like the rsa, would require 160mm conrod

[SwePatrick]

Breathing changes also with different rodlengths.
One can optimize certain areas with different rodlengths.

Short rods tend to breath better in lower rpm areas.

[Peter1962]

Wobbly, would the use of a longer rod + spacer plate be high on your priority list for tuning a ktm 250 MX bike ? What rod lenght en which brand would you choose ?

[Frits Overmars]

Wobbly, would the use of a longer rod + spacer plate be high on your priority list for tuning a ktm 250 MX bike ? What rod lenght en which brand would you choose ?Peter, you might also ask Wob about the combination of a longer rod and a higher-placed gudgeon pin. That's what I would be looking for.

[Matt@TYGA]

Hi Guys,

Playing with a 110cc boxer twin with shared crankcase. Measured the case compression ratio at 1.45, which seems a little small to me. But not having much experience with the boxer doesn't help.

For the record; running straight pipes (not expansion chambers) as room is extremely limited, and the owner insists on using straight pipes so that he doesn't have to redesign his board to get them to fit.

The engine's fitted to a surf board. Propulsion is through a jetski style prop etc.

Without messing with the engine geometry it's gone from 35kmh up to 46kmh, mostly by trying many pipe lengths and a bit of reed valve and petal work, and several prop designs and pump diameters.

Anyway, the question I have is regarding the case volume. Anyone have an opinion on the ratio? I'm tempted to try something very different and see what happens.

[Peter1962]

Peter, you might also ask Wob about the combination of a longer rod and a higher-placed gudgeon pin. That's what I would be looking for.

Thank you for the suggestion, Frits !
(I did not even know that pistons for a ktm 250 were available with a higher placed gudgeon pin).

[Frits Overmars]

Neither do I, Peter. But most 250 singles use a 66,4 mm bore nowadays, so if KTM doesn't have them, chances are that you'll find suitable pistons elsewhere.

[wobbly]

The case volume would only need changing alot if you are looking for a big top end boost as I was looking for using a KTM for kart roadracing.
One model of KTM 250 has a 130 rod and I used a Vertex CR250 single ring race piston.
Yes,Frits is right ,all the 250 now have the same bore and stroke so anything will fit.
This combo needed an 8mm plate, and that gave a good case increase along with a plate behind the reed so I could fit in a VF4 from a later model KTM.

[Muhr]

Thanks you guys for valuable comments. I did some computer modeling and realyze that classical V "common finger" good enough and my idea of 90 degree pin offset require more bearing supports on shaft. Smaller torque variation not enough reason then.


Anyone know if intermediate part of jbb crank were one solid part or welding (press fit) of finger and disk?

Finally I am going to make 140cc V with 9500 rpm on max power which should weight below 3000 grammes including fuel injection.
It will be rather long ~4 month project. I think if I will make crancase precisiously then will dont need sealing ring on crankshaft.

This is my take on it.

[speedpro]

I took the RS50 out to Levels on the weekend for the Southern Classic and beat up some 250 4ts, 150 2ts and 150 4ts.
In race 2 I set the 4th fastest time of a grid of 35 bikes. Also got it up to 143km/hr with a wind break, ~136ish without. Pretty chuffed about... until I seized it at the fastest bit of the track and it put me in hospital with a bruised lung and coughing blood...

Well, your 50 is being well used Dave and even looked beautiful until we both ended up in the gravel.
http://www.grandprixmachine.com/blog/2017/12/4/rs50-racing-at-the-southern-classic

https://static1.squarespace.com/static/54f417b0e4b0ba5e061bdebd/t/5a248d178165f5067708d1f2/1512344932290/IMG_7856.jpg?format=1500w

141kmh in 1984 on a Suzuki GT50 bucket. Not much progress speed-wise really

[jbiplane]

This is my take on it.

Great Muhr!!! Me make wery close to your design, just medium part a bit wider. I did some 3d modelling and realyze V twin with common finger can be balanced perfectly. When I virtually rotate crank I achieved 0 centre of gravity fluctuation. Just balance should be relatively heavy compare opposites. May be
The main question now how sturdly fix medium part.

Could you show your assembly "exploded"? Seems pin need step in the center.

[ken seeber]

These look cool..

http://www.cyclenews.com/…/250cc-two-stroke-streetbike-bac…/

Nice colour too.


333854

[tjbw]

These look cool..

http://www.cyclenews.com/…/250cc-two-stroke-streetbike-bac…/

Nice colour too.


333854

Broken link ken?

http://www.cyclenews.com/2017/12/article/250cc-two-stroke-streetbike-back-baby/

More info on the engine would be good.

[Grumph]

141kmh in 1984 on a Suzuki GT50 bucket. Not much progress speed-wise really

I would suspect that Chris could do a bit better in a proper record attempt - Levels back straight is approached via a tightish 180 degree sweeper - and it ain't very long either...

[F5 Dave]

I considered it, although a smaller pilot would be ideal. Sadly it occurred to me bucket rules allow oversize which i had, where speed records won't.

[guyhockley]

Broken link ken?

http://www.cyclenews.com/2017/12/article/250cc-two-stroke-streetbike-back-baby/

More info on the engine would be good.

Don't understand why the race version is 288cc?

[Frits Overmars]

Anyone know if intermediate part of jbb crank were one solid part or welding (press fit) of finger and disk?It was one solid part Valery, as might be clear from the drawing of the latest JBB crankshaft that I recently posted: https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131072807#post1131072807


I think if I will make crankcase precisiously then will dont need sealing ring on crankshaft.You cannot make the diameter difference between the crankcase and the crankshaft small enough to avoid leakage because the crankshaft bends too much; it will hit the crankcase walls. You will need the labyrint, formed by the ring and the groove in the center disc.


This is my take on it.
333865No big end cage? A big end bearing is not only rotating, it is also orbiting. The centrifugal force pushes all needles to the outside of the orbit path; the outermost needles will be pressed against each other by all other needles if there is no cage to keep them separated. Then the friction will generate enough heat to destroy the bearing.

[Muhr]

It was one solid part Valery, as might be clear from the drawing of the latest JBB crankshaft that I recently posted: https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131072807#post1131072807

You cannot make the diameter difference between the crankcase and the crankshaft small enough to avoid leakage because the crankshaft bends too much; it will hit the crankcase walls. You will need the labyrint, formed by the ring and the groove in the center disc.

No big end cage? A big end bearing is not only rotating, it is also orbiting. The centrifugal force pushes all needles to the outside of the orbit path; the outermost needles will be pressed against each other by all other needles if there is no cage to keep them separated. Then the friction will generate enough heat to destroy the bearing.

No, that's right! too lazy to draw the basket, will use standard rollers

[Muhr]

Great Muhr!!! Me make wery close to your design, just medium part a bit wider. I did some 3d modelling and realyze V twin with common finger can be balanced perfectly. When I virtually rotate crank I achieved 0 centre of gravity fluctuation. Just balance should be relatively heavy compare opposites. May be
The main question now how sturdly fix medium part.

Could you show your assembly "exploded"? Seems pin need step in the center.


I made an ellipse with two phases

[Muhr]

It was one solid part Valery, as might be clear from the drawing of the latest JBB crankshaft that I recently posted: https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131072807#post1131072807

You cannot make the diameter difference between the crankcase and the crankshaft small enough to avoid leakage because the crankshaft bends too much; it will hit the crankcase walls. You will need the labyrint, formed by the ring and the groove in the center disc.

No big end cage? A big end bearing is not only rotating, it is also orbiting. The centrifugal force pushes all needles to the outside of the orbit path; the outermost needles will be pressed against each other by all other needles if there is no cage to keep them separated. Then the friction will generate enough heat to destroy the bearing.

Right should be right! Something like that:yes:

[guyhockley]

It was one solid part Valery, as might be clear from the drawing of the latest JBB crankshaft that I recently posted: https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131072807#post1131072807

You cannot make the diameter difference between the crankcase and the crankshaft small enough to avoid leakage because the crankshaft bends too much; it will hit the crankcase walls. You will need the labyrint, formed by the ring and the groove in the center disc.
I saw a prototype microlight engine at an aviation expo that was also a 90 degree v-twin with a common case. They were using a plain centre disc that ran in grooves to separate the 2 halves. A bit like the Trabant disc valves you posted. I've tried googling it but apart from a vague idea the designer was called Camus and they had some sort of regional development grant I can't narrow it down.
The Konig radial 2 strokes may have something similar but I've only seen small photos of them.
http://www.compactradialengines.com/mz430parts.html
Worth noting that most microlight engines are fairly low revving?

[jbiplane]

It was one solid part Valery, as might be clear from the drawing of the latest JBB crankshaft that I recently posted: https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131072807#post1131072807

You cannot make the diameter difference between the crankcase and the crankshaft small enough to avoid leakage because the crankshaft bends too much; it will hit the crankcase walls. You will need the labyrint, formed by the ring and the groove in the center disc.

Hi Fritz. Thanks for valuable comments. I havd same fillings, but need confirmation before cut metal. At moment I doing some balancing deflection and stress estimations. I going to make for "V" central part of disk with grove sealing ring and stepped pin.


Right should be right! Something like that:yes:
YES, with minor variations!



The Konig radial 2 strokes may have something similar but I've only seen small photos of them.
http://www.compactradialengines.com/mz430parts.html
Worth noting that most microlight engines are fairly low revving?
I have numerous photos of this engine interior. Probably worth to place somethere here, says in "odd engines"

[jonny quest]

There's always a way to make a pipe.

Try a straight pipe into a box, then stinger out of box. That would probably be better than a straight pipe. Remember pipe is 30% of a 2 strokes power

This is for Matt@Tyga, sorry missed the quote button

[wax]

has anyone here tried e85 in their bikes and taken the time to jet it in correctly. What was the result. did you get a power gain. was the engine more reliable due to it being a higher octane and a colder burning fuel.
Do you recut the combustion chamber becuase of the new fuel burn properties

[Matt@TYGA]

There's always a way to make a pipe.

Try a straight pipe into a box, then stinger out of box. That would probably be better than a straight pipe. Remember pipe is 30% of a 2 strokes power

This is for Matt@Tyga, sorry missed the quote button

Sorry, I wasn't totally clear. The pipes run into a silencer box and then out again and through a one way valve system so that it doesn't ingest water when things don't go to plan. Tested with and without the valves and it doesn't make any noticeable difference so they're not causing any issues as far as one can tell.

Anyway, the pipes I can figure out, but the main question was regarding the primary compression ratio in a boxer as I don't have any prior experience.

Cheers.

[F5 Dave]

If you wore jandals could you stand on the pipes? Like if they were structural.

[TZ350]

333876 . 333875

Ok, got the pressure transducer sorted and the 4-20mA output across a 250 Ohm resistor should give me 1 to 5 Volts output suitable for an analog pressure signal into the Arduino.

The yellow pressure line will be threaded through a spring for support and the ends clipped so they don't pull of the hose tails.

I am looking forward to the weekend so I can get it back together and see what the signal looks like on the scope.

[Frits Overmars]

There's always a way to make a pipe. Try a straight pipe into a box, then stinger out of box. That would probably be better than a straight pipe. Remember pipe is 30% of a 2 strokes power.There is always a pipe effect too, unless there's no pipe at all.
Straight pipes aren't nearly as effective as expansion chambers, but they too can have favourable or unfavourable lengths and diameters.
Start with a long pipe and keep cutting pieces off until the power decreases; then you will have found were the optimum was. But it was probably a relative, not an absolute optimum, because with a different diameter you'll also need a different optimum length: more diameter usually requires more length and vice versa.
By the way, that goes for the headers of full-blown expansion chambers too.

Regarding those 30% of power I think we need to have a wee chat Jonny.
Jan Thiel tested it twice. The first time was with a 50 cc Bultaco that produced about 20 hp. Without the pipe it gave 4,5 hp.
The second time was with an Aprilia RSW125. In those days it produced 52 hp. With the pipe removed, and with carburation and ignition painstakingly re-optimized for the new circumstances, that engine gave 17,5 hp. So it's safe to say that a good pipe on a good engine can triple its power. That's not 30% more; it's 200% more.

[WilDun]

..................... So it's safe to say that a good pipe on a good engine can triple its power. That's not 30% more; it's 200% more.

Frits, you have convinced me about having a good pipe! but, (even though it isn't relavent within the racing rules here) in the wider world of two strokes, is there a way around the bulky pipework - eg the use of straight pipes, being assisted by forced induction? - I realize of course that there are issues with port timing, (probably needing some careful design, like earlier exhaust closure),for forced induction.

Let's face it, the two stroke racing scene will always be a spinoff from the use of two strokes in the wider world. I believe it is essential in the overall 2T scene (and of course for the continuation of the racing two stroke) to address the use of huge expansion chambers in the bigger size cylinders.
This issue will hinder the sales of larger road machines (as will the 2T smoke)!

[nitro2tfx]

is there a way around the bulky pipework



Maybe. Doubtful if there will be any brainstorm good enough to create a smallish exhaust capable of generating the same power as the huge expansion pipes, but something on the order of 2/3 - 3/4 the power might suit some applications.

[wax]

So no one has tried e85 then

[TZ350]

So no one has tried e85 then

E85 is currently illegal for Bucket racing here in NZ under the no alcohol rule. .... so no, no one here has tried the forbidden fruit right .... :msn-wink: ....... 333877



E85 ... I have no experience with it myself but a Guy who runs it in an air cooled 350cc 2T VMX bike tells me that when the engine gets hotter than 70degC you have to richen up. So you either run around for the first 2-3 laps rich as hell then fine for the rest of the race or you get in 3 good laps and then risk detonation for the rest of the time you are out there, the choice is yours. 4T's with O2 sensors don't seem to have this problem. Temperature switchable power jet might be an answer for air cooled 2T's.

From what I hear, E85 does not make anymore power than petrol but there might be reliability advantages from the extra cooling if a 2T can be run rich, maybe splash in a bit of methanol too if you can because it likes being run rich.

[F5 Dave]

Or an Intelejet system coupled to an Intelligent rider to adjust it.

[2T Institute]

E85 is currently illegal for Bucket racing here in NZ under the no alcohol rule. .... so no, no one here has tried the forbidden fruit right .... :msn-wink: ....... 333877



E85 ... I have no experience with it myself but a Guy who runs it in an air cooled 350cc 2T VMX bike tells me that when the engine gets hotter than 70degC you have to richen up. So you either run around for the first 2-3 laps rich as hell then fine for the rest of the race or you get in 3 good laps and then risk detonation for the rest of the time you are out there, the choice is yours. 4T's with O2 sensors don't seem to have this problem. Temperature switchable power jet might be an answer for air cooled 2T's.

From what I hear, E85 does not make anymore power than petrol but there might be reliability advantages from the extra cooling if a 2T can be run rich, maybe splash in a bit of methanol too if you can because it likes being run rich.

I have found the opposite, as little as 10-15% e85 in ULP will make a air or water cooled engine run far cooler and with the alcohol won't detonate (can still have lean seizures).

[TZ350]

I have found the opposite, as little as 10-15% e85 in ULP will make a air or water cooled engine run far cooler and with the alcohol won't detonate.

I was only relating what I had been told and if a 2T does run cooler that is very interesting, certainly worth looking at.

[DoldGuy]

Peter, you might also ask Wob about the combination of a longer rod and a higher-placed gudgeon pin. That's what I would be looking for.

Frits,

Help a slow learner like me understand why you would prefer the longer rod with the pin higher in the piston.

Is this just for the reduction in angle...longer/ less dwell at TDC / BDC...more leverage?

Again, thanks for sharing your knowledge.

[DoldGuy]

The case volume would only need changing alot if you are looking for a big top end boost as I was looking for using a KTM for kart roadracing.
One model of KTM 250 has a 130 rod and I used a Vertex CR250 single ring race piston.
Yes,Frits is right ,all the 250 now have the same bore and stroke so anything will fit.
This combo needed an 8mm plate, and that gave a good case increase along with a plate behind the reed so I could fit in a VF4 from a later model KTM.

Wobbly,

I have seen / saved pictures of the KTM you have posted & see the massive amount of work you did on the sub exhaust ports, along with the floor (75% of the area?).

Is there any more information available on this build...results / videos of this kart? Currently working on a KTM & gathering as much knowledge as possible, these KTMs have a lot of parts crossover, like the rod selections 135/132/129/125 and would change the case volume a little or a lot depending on rod / piston choices.

Thanks for sharing info.

[Fabio15]

has anyone here tried e85 in their bikes and taken the time to jet it in correctly. What was the result. did you get a power gain. was the engine more reliable due to it being a higher octane and a colder burning fuel.
Do you recut the combustion chamber becuase of the new fuel burn properties

Adegnes has:


https://m.youtube.com/user/TheAdegnes


https://m.youtube.com/results?q=2%20stroke%20stuffing&sm=1

https://m.youtube.com/watch?v=MbfQpjWMQN0

[speedpro]

e85 is ethanol. I only have experiance with methanol but to an extent there are similarities. One of the similarities of interest is the latent heat of evaporation. High performance 2-strokes are fuel cooled. Petrol absorbs a certain amount of heat as it evaporates. Methanol, and probably ethanol, absorbs heaps more. A big blown methanol V8 will have frost form very quickly on the blower and manifiold at idle(3000rpm). The more heat the fuel can remove from the engine the better, obviously, and ethanol absorbs a fair amount more than petrol. Methanol from experiance absorbs heaps.
Run the engine rich and it absorbs even more plus you get the advantage of a buildup of detonation resistance. Trust me it will still detonate if you try hard enough but no worse then petrol in that regard.
2-strokes stand to benefit substantially from being allowed to use ethanol or methanol. Heaps of compression and cooling being the factors. Without pretty much unobtainable compression, or boost, 4-strokes will not gain a similar benefit.

[jbiplane]

Maybe. Doubtful if there will be any brainstorm good enough to create a smallish exhaust capable of generating the same power as the huge expansion pipes, but something on the order of 2/3 - 3/4 the power might suit some applications.

I use 2 (warez can be found on torrents) "Lotus engine simulation" and "Ricardo Vawe" to make small enough exhaust.
Other idea try ro read about 1/4 vawe mufflers (different trade names, like "magic mufflers"). They are 2 times shorter
than classical resonators and produce much wider powerband with a bit less max power.