ESE's works engine tuner

[Javier Ruda]

several configurations have been tested.

ignition is erratic. clearly visible under the strobe light.


Bonsoir philou, this is how to match flywheel and stator, from rotax 123 service manual. Your layout seems very different, it may be difficult to follow the procedure.

[wobbly]

It does not matter that the CDI is a P2 - just turn off the second channel and it will operate as a single.
The input trigger system I have my doubts it will work.
The CDI input works when it sees a dropping voltage from the trigger pass thru zero volts - and having two magnets side by side with a pair of close signals one after the other
is not what was designed for at all.

In fact all Ignitech DC DCCDI are designed to use a normal reluctor pickup , that has a magnet surrounded by the coil , and a voltage is generated by a non magnetic trigger lobe on the flywheel.
Having magnets inside ( or outside ) only works with Hall Effect sensors , and this setup has to be ordered as a special input from the factory - only 4Ts use this usually.
This input is not switchable between the two systems , its one or the other.
The Ignitech has a similar input setup to a Zeel , except the Ignitech uses a base advance of the actual trigger firing position BTDC - the Zeel must have a base advance greater than the max advance in the curve.

[philou]

it is indeed an inductive sensor that is used. Not hall sensor.

zeeltronic does not want to bother with SEM ignitions.

I guess that the passage of the 2 magnets side by side gives 2 top too close and that the case is lost

I tested all possible configurations and no change

350549



Édit : ignitech provides an add-on for the SEM.



I have to check if I have correctly connected the blue wire of the case with the black ground of the stator.
the load coils being on the same part as the pick-up. maybe my problem comes from there.

[wobbly]

That is very wierd then , as only Hall Effect triggers use a magnet in the flywheel - an inductive trigger will not work correctly using magnets.
There is a way of programming a two lobe / close gap input.
The factory did one for me when splitting the second lobe in 1/2 on an RD400 to get rid of the wasted spark.
But that is on a very old hard drive somewhere - its done by creating a " virtual single lobe ".

[philou]

a gutted SEM stator.

the pickup is just a winding on the same metal frame as the CDI charging coils.

I will check my wiring. maybe i did shit
I retain the idea of the virtual single lobe.



350553

[Muciek]

You will probably need a circuit to convert that pickup signal into the normal like pickup coil ". Friend did work with ktm lc4 with sem ignition and he was fighting with that too (he made cdi replacements with 2 ign curves)

[husaberg]

You will probably need a circuit to convert that pickup signal into the normal like pickup coil ". Friend did work with ktm lc4 with sem ignition and he was fighting with that too (he made cdi replacements with 2 ign curves)

i wouldn't be surprised if he couldn't have put on a later Husaberg with that already.
i know my old 01 501 does. pretty sure it SEM as well.

[Muciek]

i wouldn't be surprised if he couldn't have put on a later Husaberg with that already.
i know my old 01 501 does. pretty sure it SEM as well.He was selling DC CDI replacement for the older SEM ones , because HV charging coils were getting old and failed in the stator (sometimes it was CDI box or both of them ). KTM had 12v rectifier and big capacitor that was enough to get it easily (if you could name it that way) started .

[philou]

an American offers the SEM stator rewinding service.
apparently with success.

his observation is that the quality of the original thread is crap.

ignitech tells me that their boxes work with it.
I explained the problem to them.
at the strobe light, the cdi is lost. ignition timing is completely random, with variations of over 45 degrees leading and lagging.

[Niels Abildgaard]

he second lobe in 1/2 on an RD400 to get rid of the wasted spark.
".

Excuse my ignorance,but what was benefit of getting rid of wasted spark?

[philou]

I think not wasting energy for nothing and having coil filling time

[wobbly]

The wasted spark has two compromises , firstly each plug only sees 1/2 the energy generated by the source coils , and secondly one spark jumps from ground to the electrode
the other one jumps from the electrode to ground to complete the circuit. ie one is reverse polarity causing missfires and power loss at high rpm/power levels..
Setting up two independant CDI's gives a huge increase in spark energy , and both are the same.
When making near on 100 RWHp its mandatory , the stock system simply didnt cope at all.

[F5 Dave]

Actually that's a good point. I never got around to buying separate coils for my RZ, must do that some time . . . along with a billion other things and 98.6hp is enough for the road.

[husaberg]

Other than the RDLC what 2 pot 2T bikes actually had a wasted spark std? i cant really think of any?

[katinas]

Other than the RDLC what 2 pot 2T bikes actually had a wasted spark std? i cant really think of any?

Same for other two parallel twins, Suzuki RG 250 and Kawasaki KR 1.
Once for RG 250 we adapted the old racing ignition with inner rotor (stator molded with blue plastic). Weaker spark and jetting became nightmare until, after two race, spark plug gap was reduced to 0,25 mm. From then works and revs fine, even on richer side.

[wobbly]

Same solution to Selettra on old Rotax 250 Tandem Twins. 1/2 the plug gap and it " functioned " just , when tuned properly.
This is where the R7376 plugs would have been a godsend , way less voltage required to ionise the gap.

[Niels Abildgaard]

The wasted spark has two compromises , firstly each plug only sees 1/2 the energy generated by the source coils , and secondly one spark jumps from ground to the electrode
the other one jumps from the electrode to ground to complete the circuit. ie one is reverse polarity causing missfires and power loss at high rpm/power levels..
Setting up two independant CDI's gives a huge increase in spark energy , and both are the same.
When making near on 100 RWHp its mandatory , the stock system simply didnt cope at all.

My BMW R25/3 single cylinder used a a cam on crank and worked very well(sometimes)
My Citroen Mehari (2CV engine) did the same and had a twin coil and worked well( when dry)
I have not imagined the japanese to be such cheapskaters and use one cam,coil and two plugs in series.
Thank You for a clear describtion of reason for and benefits of modifications.

[Niels Abildgaard]

Same for other two parallel twins, Suzuki RG 250 and Kawasaki KR 1.
Once for RG 250 we adapted the old racing ignition with inner rotor (stator molded with blue plastic). Weaker spark and jetting became nightmare until, after two race, spark plug gap was reduced to 0,25 mm. From then works and revs fine, even on richer side.

Thank You for a nice reading session on high power 2 pot 2 strokes 250-350 from the nineties.
I remember seing a Youtube of a RD350 tuner doing 170 km/h on rearwheel alone on a former east german airfield.
What was best V2 or inline 2?
My dream is to have been a rich man and had used life succesfully to prove that a common crankchamber 350 V2 could beat all competing 250 separate crankchambers on the serious values ,power,price,mass, external volume and vibrations
Will do next round on the circuit

[andreas]

Thank You for a nice reading session on high power 2 pot 2 strokes 250-350 from the nineties.
I remember seing a Youtube of a RD350 tuner doing 170 km/h on rearwheel alone on a former east german airfield.
What was best V2 or inline 2?
My dream is to have been a rich man and had used life succesfully to prove that a common crankchamber 350 V2 could beat all competing 250 separate crankchambers on the serious values ,power,price,mass, external volume and vibrations
Will do next round on the circuit

I remember talking to Ebbe at Eptune here in sweden, about a boxer 250 with joined crankcase project he had had high hopes for, but results were disapointing. The reason is best described by Frits, but basically the distribution of gas to each cylinder becomes uneaven and snowballs to the point where one is too starved to make any power.

[husaberg]

I remember talking to Ebbe at Eptune here in sweden, about a boxer 250 with joined crankcase project he had had high hopes for, but results were disapointing. The reason is best described by Frits, but basically the distribution of gas to each cylinder becomes uneaven and snowballs to the point where one is too starved to make any power.

Not to ever be so bold as to go against what frits has said, but as far as i am aware the Swissauto/Pulse/elf/MZ. etc etc was a shared case design i do not believe it was significantly lacking power. Wob would have some idea of what the output was as BSL leased one i believe.
it did appear it was constrained by the design but i don't think it lacked top end output for its cylinder design anyway
the one pic i seen of the upper crankcease looked like it was heavily shrouded to minimise the charge robbing though.ni believe this was absent on the later versions.
350556350555

i think it was a bit over 100 deg v4


Same for other two parallel twins, Suzuki RG 250 and Kawasaki KR 1.
Once for RG 250 we adapted the old racing ignition with inner rotor (stator molded with blue plastic). Weaker spark and jetting became nightmare until, after two race, spark plug gap was reduced to 0,25 mm. From then works and revs fine, even on richer side.

Cheers for the info

[andreas]

In this configuration there would be a type of seal running on the middle crank web between the two cylinders that are closest, maybe this is what you refer to as "heavily shrouded". Are you sure this is not present in the examples you have given above?

[husaberg]

In this configuration there would be a type of seal running on the middle crank web between the two cylinders that are closest, maybe this is what you refer to as "heavily shrouded". Are you sure this is not present in the examples you have given above?

Positive have a look at the crank.... and the other picture. The shrouded are is where the conrod pokes through.
the two cylinders in the v share a case ,the seal seperates the parrallel cylinders which do not.
the pics are fuzzy but its the best i have sorry
350560
here is a close up of the crank i think wob mentioned 10G
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=300967&d=1410907287
or read the text.
350557
Click on atttachement three times.
the best seal version of what you are attempting to describe would be a ring sealed one was the french v twin Jean bb .... he did with the seal on a disc like a piston ring lab seal. first i seen of these was the DKW v3's
350558350559

[Niels Abildgaard]

I remember talking to Ebbe at Eptune here in sweden, about a boxer 250 with joined crankcase project he had had high hopes for, but results were disapointing. The reason is best described by Frits, but basically the distribution of gas to each cylinder becomes uneaven and snowballs to the point where one is too starved to make any power.

Makes project even more tempting for my next life.
Two honourable experts claiming it cannot work.
Lovely when I succed.
Nuclear fission was first proven in Germany and Werner Heissenberg(Big Gun) calculated that it could not be selfsustaining(Big Bomb)
Normal aeroplane pratice was to make them stable in pitch.Along came F16 that is not pitch stable in the subsonic speed range and it is a well selling thing.
Some kind of squezing the transfer ports in the offending cylinder can maybe do the trick.According to Frits it takes 50 revs to reestablish resonnance after non ignition.
It dot need to react100% within one rev.

[Niels Abildgaard]

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=350559&d=1643897180

This is technology for separating crankchambers on Outboard two stroke V engines more or less.
Made in very big numbers
I dreamt of something lower mass for an aeroplane engine

https://www.homebuiltairplanes.com/forums/threads/side-valved-two-strokes-for-angels.32119/

[philou]

he seems to be very happy with it

https://digilander.libero.it/Crislyfe/My%20Aprilia%20Proto%20250%20/Aprilia%20Proto%20250%20Bicilindrico%20(32).jpg

https://digilander.libero.it/Crislyfe/My%20Aprilia%20Proto%20250%20/Aprilia%20Proto%20250%20Bicilindrico%20(54).jpg

http://www.2t-special.it/forum/viewtopic.php?f=14&t=4378

[andreas]

Yes Husa, it seems to be as you say it is.

[katinas]

Niels, maybe another risk of unit crankcase chamber, could be detonation in overcharged one cylinder, at certain different condition.

For NS 500 3V engine, because of the higher temperature, center lower cylinder compression was reduced in comparison to vertical side cylinders.

Just remember 1991 Hans Becker modified TZ 250 DP4 engine with Hans Hummel big bore cylinders. Huge over-square 67,5 mm bore and std 50,7 mm stroke. 363 cc -91,2 hp at 10668 rpm, 20 hp over std 250 cc
Later 54.5 mm stroke crank was used with slightly smaller pistons, 375 cc.
Big surprise that this kit still available
http://www.geckomotorcycles.co.uk/magento/4dp-3xv-yamaha-tz-375cc-hh-big-bore-kit.html

[speedpro]

350558350559

Reminds me of a Martin Jetpack V4 crankshaft

[husaberg]

Reminds me of a Martin Jetpack V4 crankshaft

oddly i cant remember posting this stuff at all wtf

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131038334#post1131038334



No but on the link above the cylinders in the background of the link above look to be CP industries liger
329705
http://www.cpindinc.com/pub/view_product/63?lm=5&name=3101-9779-144
ie same crowd that does the big bore banshees as well as CR500's

Also the cases apear to have a awesome finish esp the one in the background
looks to me like diecast.
329715
I also note the piston ring crase seal
329706

Here is the staff for ifitech
http://iffitech.com/#staff-module
They even have one of charlies angels.:facepalm:
hes the guy that did this, it looks as if its been rebranded.
http://www.stuff.co.nz/motoring/5614635
http://iffitech.com/wp-content/uploads/2016/04/086-089_Denver-Lawson-Web.pdf

Maybe rob should call in and visit them for a look.

Here is a Konig cranks
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=246575&d=1315566975
350569350568
as well as the modern better made ones
350565350566350567

[Niels Abildgaard]

It has been argued that having a two cylinder boxer two stroke will beunstable in amount of air fuel mixture distribution from an undivided crankchamber.
The Koenig won a lot of races ,was basiclly two independent air/fuel wise boxers with two cylinders each served from an undivided crank case.
Is that fact or fiction?
A picture of the rotary valve face will b very nice if someone has one.Please?
I got a monster McCullough 4 cylinder two stroke drone engine from our Navy once and I seem to remember that it was two crankchambers feed from reed valves from one common carb?

[andreas]

Well it wasn't so informative.

[husaberg]

It has been argued that having a two cylinder boxer two stroke will beunstable in amount of air fuel mixture distribution from an undivided crankchamber.
The Koenig won a lot of races ,was basiclly two independent air/fuel wise boxers with two cylinders each served from an undivided crank case.
Is that fact or fiction?
A picture of the rotary valve face will b very nice if someone has one.Please?
I got a monster McCullough 4 cylinder two stroke drone engine from our Navy once and I seem to remember that it was two crankchambers feed from reed valves from one common carb?

Hi here. its shut though LOL
.https://www.koniggrandprixracers.com/s/cc_images/cache_2454268910.jpg?t=1613660985

here are some others but the one Andreas has found is the best
350589

350592350571350574350575350576

[katinas]

Another unit crank chamber type, copy of Konig, that was made in small series. Both with the same 54 mm stroke, but 45,3 mm bore for 348 cc. Runs on Methanol

Veterok-70 348 cc 70 hp at 9000 rpm
Veterok-100 496 cc 100 hp at 9000 rpm

[husaberg]

i cant recall who did this one.
Frits will though. it was out of some sidecar

okay

here are some pictures of the Stredor, a work of art made by Egbert STREuer and Rinus DORgelo. This machine was on display at the Speedshow in Cafe Hofsteenge in Grolloo
https://www.flickr.com/photos/teamheronsuzuki/albums/72157594456814612
350584350587350588
plus some others one reed aparently based on the yz250
no idea of the internal layout
350586
The other I would like to replicate (as for no other reason it looks frigging cool)
I can't remember what it was called but i think it was three leter E..
350585

[Niels Abildgaard]

Hi here. its shut though LOL
.https://www.koniggrandprixracers.com/s/cc_images/cache_2454268910.jpg?t=1613660985

here are some others but the one Adereas has found is the best
350589

350592350571350574350575350576

Thank You for pictures.
All are common chamber for two opposed boxer cylinders (Me think)
Seem to remember that exhaust pipes was not very prominent and certainely not as big as present ones.

[Niels Abildgaard]

Another unit crank chamber type, copy of Konig, that was made in small series. Both with the same 54 mm stroke, but 45,3 mm bore for 348 cc. Runs on Methanol

Veterok-70 348 cc 70 hp at 9000 rpm
Veterok-100 496 cc 100 hp at 9000 rpm

Thank You for picture.Do You have a picture showing Exhaust arrangement?
It is I think again common crankchamber Boxer

[Niels Abildgaard]

i cant recall who did this one.
Frits will though. it was out of some sidecar

okay

https://www.flickr.com/photos/teamheronsuzuki/albums/72157594456814612
350584350587350588
plus some others one reed aparently based on the yz250
no idea of the internal layout
350586
The other I would like to replicate (as for no other reason it looks frigging cool)
I can't remember what it was called but i think it was three leter E..
350585

Thank You for lovely pictures of mechanical nigthmares.
Most certainely divided/rotary sealed individual crankchambers and intended for 4 full blown resonance exhaust pipes.

[Niels Abildgaard]

Boxers can have common or sealed individual crankcase chambers.
For direct exhaust they can be common

http://miniairboatassoc.com/forum/showthread.php?2360-McCulloch-0-100-1-Drone-Engine

The disappointment Andreas swedish friend had (letter 36519)was most likely trying undivided crankchambers with modern resonnance exhausts.
Modern military drone two stroke boxers do not have tuned exhausts .

[katinas]

Thank You for picture.Do You have a picture showing Exhaust arrangement?
It is I think again common crankchamber Boxer

This is the only other picture that I have of this engine.

Add other outboard racing engine picture from sixties. This is the development of soviet 1962 single-cylinder racing engine "Hurricane-175", developed on the basis of the Zimmermann disc intake engine design, a sample of which was handed over to soviet racers by its designer Daniel Zimmerman.

175 cc 60,5 x 60,5 mm bore/stroke
27 hp on pump fuel
Carb 30mm
Ex 189
Intake 198 opened 52 after BDC
Trans two mains-132 C-129
Exhaust stainless 0,5 mm

[Niels Abildgaard]

This is the only other picture that I have of this engine.

Add other outboard racing engine picture from sixties. This is the development of soviet 1962 single-cylinder racing engine "Hurricane-175", developed on the basis of the Zimmermann disc intake engine design, a sample of which was handed over to soviet racers by its designer Daniel Zimmerman.

175 cc 60,5 x 60,5 mm bore/stroke
27 hp on pump fuel
Carb 30mm
Ex 189
Intake 198 opened 52 after BDC
Trans two mains-132 C-129
Exhaust stainless 0,5 mm

Lovely and shows that Boxer exhaust pipes were not tuned by modern standard.
Do You know power and rpm of Boxer?

[katinas]

Lovely and shows that Boxer exhaust pipes were not tuned by modern standard.
Do You know power and rpm of Boxer?

Boxers Veterok 70 and Veterok 100
348 cc 70 hp at 9000 rpm
496 cc 100 hp at 9000 rpm

Guseppe Rossi made a very nice engines, its like mix of Konig boxers with Jan's type cylinders and reed valve. Looks like was tested two types for 500 cc, with pairing crank chamber and separated for all four. Paired crank chambers version crankshaft with additional outside bearing to prevent deformation. They still produce 350 cc boxer with unit crank chamber, but on 250 cc base, so its over square bore/stroke like RD 350.
Last year they won WC F 500 with Erko Abrams and F 125 with Sanna Aslav Kaasik.

[philou]

The plates in the crankcase are back in fashion.

crankshaft rotates in the normal direction

350602350603350604350605

[acr]

Always thought a 500VTwin would make a cracking roadbike in the 90s. . . . If only someone made one. . . . ;)

https://en.wikipedia.org/wiki/Bimota_V_Due

[husaberg]

Boxers Veterok 70 and Veterok 100
348 cc 70 hp at 9000 rpm
496 cc 100 hp at 9000 rpm

Guseppe Rossi made a very nice engines, its like mix of Konig boxers with Jan's type cylinders and reed valve. Looks like was tested two types for 500 cc, with pairing crank chamber and separated for all four. Paired crank chambers version crankshaft with additional outside bearing to prevent deformation. They still produce 350 cc boxer with unit crank chamber, but on 250 cc base, so its over square bore/stroke like RD 350.
Last year they won WC F 500 with Erko Abrams and F 125 with Sanna Aslav Kaasik.

JPbiplane wasi nterested in making drones esp boxer ones and posted some stuff ages ago

Any idea what engine is it and specs ~1940 production, used by German military.
Scavenging through piston
346564
346565
346566


Like Niels wrote, it seems to be a boxer with Schliha (spelling!) scavenging through the piston. And the shielded spark plug caps suggest aviation use.
I wonder about the drone application though. Drones were mainly used for target shooting practice, but back then the German Wehrmacht and Luftwaffe had no shortage of real targets.
346578 346577

[Javier Ruda]

You could drop the cylinder to get enough material above the A port for more axial angle , but then all the ports BDC edges will be low - and alot of extra grinding needed to restore the other ports.
Better to epoxy the A roof with increasing thickness of fill as it goes around the outer radius - this will keep the timing as needed but give you a proven axial scavenging pattern.
You dont need to go to Italy to see the Leaning Tower , we can all have one in our workshop.

Hello wobbly, finally I found some time and disassembled the cylinder from the engine. I measured roof angles using soldering wire, trying to follow the flow direction. Both ports are 17.1º.
350613

Does anybody knows a suitable epoxy for A-port available in Europe?

[philou]

almost any epoxy is suitable.

easily available in Europe. Loctite epoxymatic 3455

[Frank S.]

Does anybody knows a suitable epoxy for A-port available in Europe?

JB Weld, available at Ebay

[philou]

jbweld also works. have seen it often, because many photos of port transfers with epoxy on the internet are made by Americans.

jbweld and available in any hardware store at home. the product is nothing special.

cylinder is made with quiksteel.

knows the preparation with the degreasing that makes the outfit

350614

350615

[katinas]

Other Loctite hi-temp https://www.ebay.co.uk/itm/194709724508?epid=2320305472&hash=item2d559a9d5c:g:QEUAAOSwGrhh1rLF
And less viscosity for AL repair https://www.ebay.co.uk/itm/113124922258?hash=item1a56c55392:g:cNsAAOSwvApaQMy N
I tried both.

Yes Husa, remember this very interesting topic from Oddball pages two years ago. Maybe in theme, add picture from last weekend trip to Trakai city and was very surprised to "meet" this monument. Firefighter engine.

Third picture again boxer for rc models.

[Javier Ruda]

Thank you all for the answers :niceone:
What a nice forum this is!

By the way, following my new hobby of bending soldering wire, I measured the transfer roof ports of Italkit cylinder for Rotax 122.

They are complete flat!

I guess this is a compromise with the overbore cylinder that they also sell, so that the transfer timings are not lowered on the overbore.

[Frits Overmars]

The plates in the crankcase are back in fashion. crankshaft rotates in the normal direction
350602350603350604350605I would call it a piston stuffer rather than a crankcase plate. It's usually done in order to reduce the crankcase volume, but it can do some good just the same: it can guide the inlet flow to the transfers, and it creates some pumping of fresh mixture inside the piston, to the delight of the small end bearing and the piston crown temperature.

[Flettner]

Other Loctite hi-temp https://www.ebay.co.uk/itm/194709724508?epid=2320305472&hash=item2d559a9d5c:g:QEUAAOSwGrhh1rLF
And less viscosity for AL repair https://www.ebay.co.uk/itm/113124922258?hash=item1a56c55392:g:cNsAAOSwvApaQMy N
I tried both.

Yes Husa, remember this very interesting topic from Oddball pages two years ago. Maybe in theme, add picture from last weekend trip to Trakai city and was very surprised to "meet" this monument. Firefighter engine.

Third picture again boxer for rc models.

We meet some guys in Siberia with a jet boat. An aluminium dingy with twin two cylinder twostroke engines, looked similar. We told them through our interpreter the jet boat was a NZ invention. No they insisted, Russian invention. The jet units looked very much like a copy of a Hamilton single stage jet.
All they wanted to do was have a drink with us, Vodka.
Haha, those were the days.

[wobbly]

The Pulse 500Gp project wasnt a lease deal , it was a completely new bike built by the Roberts Team in England - sponsored by BSL and Hacket the bungy man.
The SwissAuto engine had reworked all but copies of factory Honda RS125 cylinders and pipes , it made around 180 Hp , making it as good as anything on track at the time.
Its crankshaft was hugely expensive to make in special materials to prevent failure of the integral pins conected to the common center wheel, and these proved
reliable if religeously lifed and swaped out.
But the engine was very compact and made for very good chassis dynamics.

The question about a V vs a parallel twin has been very well researched by many , and the consensus now appears to fall in favour of the parallel version.
This gives a completely symetric inlet and exhaust layout , whereas the V is always compromised in this regard - when packaged for racebike use.
The KTM 250 GP engine was the best proponent of this approach , with 90* firing and a balance shaft.
Dr Jeff is drawing a 500 version of this with the cylinders turned around and a balance shaft driving twin RV across the front , with gibs etc thus using all available current sota tech.

[diesel pig]

The Pulse 500Gp project wasnt a lease deal , it was a completely new bike built by the Roberts Team in England - sponsored by BSL and Hacket the bungy man.
The SwissAuto engine had reworked all but copies of factory Honda RS125 cylinders and pipes , it made around 180 Hp , making it as good as anything on track at the time.
Its crankshaft was hugely expensive to make in special materials to prevent failure of the integral pins conected to the common center wheel, and these proved
reliable if religeously lifed and swaped out.
But the engine was very compact and made for very good chassis dynamics.

The question about a V vs a parallel twin has been very well researched by many , and the consensus now appears to fall in favour of the parallel version.
This gives a completely symetric inlet and exhaust layout , whereas the V is always compromised in this regard - when packaged for racebike use.
The KTM 250 GP engine was the best proponent of this approach , with 90* firing and a balance shaft.
Dr Jeff is drawing a 500 version of this with the cylinders turned around and a balance shaft driving twin RV across the front , with gibs etc thus using all available current sota tech.

This makes me hope some one can post some cutaway drawings or disassembly photos from a KTM 250 GP engine or Dr Jeff could show some basic pictures of Dr Jeff,s project.

[husaberg]

This makes me hope some one can post some cutaway drawings or disassembly photos from a KTM 250 GP engine or Dr Jeff could show some basic pictures of Dr Jeff,s project.

ktm photos in an album

https://www.kiwibiker.co.nz/forums/album.php?albumid=4857
from what a few have said it was basically a parallel twin with a copy of works NSR cylinders and pipes
it did have a fuel injector to prevent seizing on overrun

[philou]

on the Swissauto where was the balance shaft located ?

[diesel pig]

ktm photos in an album

https://www.kiwibiker.co.nz/forums/album.php?albumid=4857
from what a few have said it was basically a parallel twin with a copy of works NSR cylinders and pipes
it did have a fuel injector to prevent seizing on overrun

Great I have lost my self into the world of Husaberg's Photo Albums.
annoying interesting mind you.

[husaberg]

Great I have lost my self into the world of Husaberg's Photo Albums.
annoying interesting mind you.

i will open them all.
I just opened a few more
There is 10 pages of albums or about 40 or so which is more than the Beatles, but they did write their own material i guess;)
https://www.kiwibiker.co.nz/forums/album.php?u=28036

[husaberg]

on the Swissauto where was the balance shaft located ?


in the blurb the cases were redesigned to have one my bet is in the bulge above the gearbox behind the cylinders.

350620

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=302045&d=1411636895

https://www.kiwibiker.co.nz/forums/album.php?u=28036

[Frits Overmars]

i will open them all. I just opened a few more.
There is 10 pages of albums or about 40 or so which is more than the Beatles, but they did write their own material i guess;)
https://www.kiwibiker.co.nz/forums/album.php?u=28036Thanks Husa, that will help us Northern-Hemispherers through the harsh winter days.
I even noticed an antique version of my FOS exhaust concept (https://www.kiwibiker.co.nz/forums/album.php?albumid=4854&attachmentid=32676 ).
It's nice to be in there, but it's a bit outdated now. In case you wish to actualize it, here is the latest version.
350621

[philou]

thank you Husa, I had never paid attention to this growth not present on other engine photos.

[lodgernz]

This sounds familiar
https://www.motor1.com/news/565427/mazda-two-stroke-engine-patent/?fbclid=IwAR34NkZK95ZzzIGOwt5j5urV0WMRTiO0FgEQ88lP fy1AHhCdFasp_0CM448

[wobbly]

I aked Dr Jeff to post some CAD shots of the new layout.
Here are a couple.

[OopsClunkThud]

Worked with Dr Jeff on the inner and outer profiles of the transfer ports. The inner wall of the ports is the shape of a logarithmic spiral, so the curvature decreases at a constant rate from the port entrance to the exit.

Here's the CAD friendly approximation that was settled on.

350624

This ZIP contains a CSV file that can be imported into fusion 360 for all the equations.
350625

[diesel pig]

This makes me hope some one can post some cutaway drawings or disassembly photos from a KTM 250 GP engine or Dr Jeff could show some basic pictures of Dr Jeff,s project.

I thought after posting this I thought I would be politely but firmly told to go away by one of the regular posters. So the responses I have got have be great!

[husaberg]

I thought after posting this I thought I would be politely but firmly told to go away by one of the regular posters. So the responses I have got have be great!

what i never mentioned was buried deep in one of the albums is a cut away RS cylinder allegedly a Kit one (but aren't they all now.)....Not sure where it was but don't think it was in the RS album?
that took some finding...


Can anyone ID the Honda cylinder it looks Sand cast with provision for RC valve rougher outside than most of the RS stuff i have seen.
But nowhere as rough and workmanlike as the works stuff i have seen? with gernarally is very rough and milling marks casting flash etc on outside.
350630350631
https://www.kiwibiker.co.nz/forums/album.php?albumid=4394
Not sure why they would bother to put "made in Japan" on a kit cylinder??? although i guess std outer cores?

[philou]

is it the one on ebay that was presented as a Yamaha TZ?

externally it looks like a 4DP of TZ

350633

[katinas]

We meet some guys in Siberia with a jet boat. An aluminium dingy with twin two cylinder twostroke engines, looked similar. We told them through our interpreter the jet boat was a NZ invention. No they insisted, Russian invention. The jet units looked very much like a copy of a Hamilton single stage jet.
All they wanted to do was have a drink with us, Vodka.
Haha, those were the days.

Great story and what a wind blew you into Siberia!!!
I found some other pictures of this engine. Again this 72 mm piston that was used everywhere in Russian engines, motorcycle, tractor starter engines, stationary engines, but actually base is from old DKW engine.
One amazing thing that could be usable for racing from all this stuff, is tractor starter engine dry clutch plates, material is very similar to what was used for racing dry clutches.

Husa, philou, yes this is TZ 250 cylinder. In Husa second picture is actually 1991 3YL cylinder with usual A, B main transfers, but C was divided in two.
DP4 cylinder used from 1992 and B was divided in two, but C narrower and one. Other identification code Y-1 and Y-2 shows port dimensions, Y-2 more tuned with wider transfers (add picture of two for comparison).

[wobbly]

Husa , the left sectioned cylinder is an RS but im sure no one can decipher the codes of factory kit units.
The right pic is a 4DP TZ

[OopsClunkThud]

Another detail on the Dr Jeff transfers.

The outer profile dimensions of the ports are adjusted so that the cross section of the port tapers linearly from entrance to exit.

Here is the approach applied to an (as yet) hypothetical 125 cylinder:
350638
350637

[katinas]

Husa, found these photos with divided into parts NSR 500 cylinder. Third photo of KR3

[Condyn]

I have to ask, and maybe I missed something, what is Dr. Jeff’s engine going in? The LSR bike? Is he casting his own cylinders this round?

Very impressive work to all parties involved.

[wobbly]

Im trying to get my hands on a bare Pulse 500GP chassis I know is here in NZ , but Jeff has another couple of ideas.

[husaberg]

is it the one on ebay that was presented as a Yamaha TZ?

externally it looks like a 4DP of TZ

350633

that expalins why it looks so odd in the PV

i know at least one of the later Cagivas were Bridged ex port like a Honda so it makes sense that there would be Yamaha ones they copied off?
it was years ago i thought that was the one that was propertied to Be Kit or NSR but so many pictures do many years by the code it looks like it was off EBay
I think from the store that sells a lot of RS and TZ stuff whose name i cant recall.
edit:spanking:


oh i just seen wobs post i have photos all mixed up.


Husa , the left sectioned cylinder is an RS but im sure no one can decipher the codes of factory kit units.
The right pic is a 4DP TZ

[41juergen]

Great story and what a wind blew you into Siberia!!!
I found some other pictures of this engine. Again this 72 mm piston that was used everywhere in Russian engines, motorcycle, tractor starter engines, stationary engines, but actually base is from old DKW engine.
One amazing thing that could be usable for racing from all this stuff, is tractor starter engine dry clutch plates, material is very similar to what was used for racing dry clutches.

Husa, philou, yes this is TZ 250 cylinder. In Husa second picture is actually 1991 3YL cylinder with usual A, B main transfers, but C was divided in two.
DP4 cylinder used from 1992 and B was divided in two, but C narrower and one. Other identification code Y-1 and Y-2 shows port dimensions, Y-2 more tuned with wider transfers (add picture of two for comparison).

From my knowledge the Y-1 stands for "cylinder number 1 (left hand side)" and Y-2 stands for "cylinder number 2 (right hand side)" for the Yamaha V engines, the suffix behind 4DP e.g. 01 stands for the different versions / port setups during the whole years the 4DP / 4TW was sold...

[philou]

does anyone have any pictures of the inside of the flowbench superflow SF60 or even better, a copy of the manual?

impossible to find it.

[jfn2]

I have a copy of the SF110/120 manual, if that will help.

[porttiming124]

does anyone have any pictures of the inside of the flowbench superflow SF60 or even better, a copy of the manual?

impossible to find it.

I'm sure I have a hard copy of the manual at home. I will check when I return later.

[porttiming124]

does anyone have any pictures of the inside of the flowbench superflow SF60 or even better, a copy of the manual?

impossible to find it.

Philou give me your e-mail adress .

[katinas]

From my knowledge the Y-1 stands for "cylinder number 1 (left hand side)" and Y-2 stands for "cylinder number 2 (right hand side)" for the Yamaha V engines, the suffix behind 4DP e.g. 01 stands for the different versions / port setups during the whole years the 4DP / 4TW was sold...

Interesting, because I have three DP4 cylinders with same suffix 00, but two cylinders marked Y-1 and one, with wider transfers, marked Y-2.

Add picture with temperature distribution from plug.

[porttiming124]

Philou give me your e-mail adress .

I sent you a scan of the manual.
Hope it can help you.
Patrice.

[philou]

yes well received. thanks again.

husa a photo for your album

350671

[husaberg]

yes well received. thanks again.

husa a photo for your album

350671

Beautiful a 750 one is it?
I think there is a NR album? no there wasnt' but there is now.
i have some stuff to add to it later
I have some stuff on the original and the 750 Malc Campbell rode in one of the Swan series about 89?
edit 87

https://www.youtube.com/watch?v=t841nHoOjIY
plus on the oval piston twin turbo 250 they made up for Freddy
if i still smoked it would make a neat ashtray:2thumbsup

[pete376403]

yes well received. thanks again.

husa a photo for your album

350671
Thats a long crankpin. What went in between? Any pics of the crankshaft?
Edit: belay that, found a pic of the crankshaft - a Main bearing goes in there

[husaberg]

Thats a long crankpin. What went in between? Any pics of the crankshaft?
Edit: belay that, found a pic of the crankshaft - a Main bearing goes in there
https://i.imgur.com/H2pRYyk.jpg

or later
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTBWquLjlY5FWR0pG5pY-dsWZj6CPAypvrrtg&usqp=CAU

https://images.cmsnl.com/img/partslists/crankshaftpiston_bigect7n91e__1300_58d0.gif

350674 350675 350676 350677
clik on them three times;)
https://magazine.cycleworld.com/article/1987/8/1/inside-the-nr

[Frits Overmars]

FOS software download link, valid until February 17, 2022

https://we.tl/t-A61fCirINx

I wrote these programs in the course of over five decades for my own personal use and I never bothered to make them user-friendly, so you may have to do some experimenting on your own, as I will not have time to answer questions.
The lot runs on MS-DOS 6.2 or Windows 98 (I recommend Win98SE) so either dig up an old computer or use an emulator. On my Win10-laptop I use VMWare Player.
I advise against DOSBox 0.74 because that is essentially a stripped-down version of MS-DOS 5; it will run some of the programs, but not all of them.

[JanBros]

thank you Frits

[porttiming124]

Thank you Frits

[Javier Ruda]

Downloaded, thank you Frits!

[OopsClunkThud]

huge thanks Frits

[Javier Ruda]

The lot runs on MS-DOS 6.2 or Windows 98 (I recommend Win98SE)

Hello Frits, the View3d in MS-DOS is amazing, hats off!!!

[Frits Overmars]

Hello Frits, the View3d in MS-DOS is amazing, hats off!!!Thank you Javier. I wrote the first version of View3D about ten years before today's standard, SolidWorks, was introduced :D.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/jvUafsQQwNI" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Making noise on the dyno.

[F5 Dave]

I'm just kinda getting the feeling a bidlot or athena barrel and some time on a dynojet would be a good starting point. From there he has a test engine he could put on his dyno and say 16hp equals. . . Adjust. Adjust. 16hp.

Right.

[husaberg]

I'm just kinda getting the feeling a bidlot or athena barrel and some time on a dynojet would be a good starting point. From there he has a test engine he could put on his dyno and say 16hp equals. . . Adjust. Adjust. 16hp.

Right.

Didn't he initially have a Dyno built from an Electric motor fwith the wheel running directly of the stator?

edit today 8.25 17/2./22


Yep
316720


Thanks!

All I did was tear out the windigs.
316742
316743
316744


2.17kgm2, the plan is to make a detachable flywheel for the axle, bumping it up to around 6-7kgm2 when needed.


I share your concern. The bearings should be fine up to 4500rpm, more with limited lifespan(skf 6316,6319), the rotor at least 3000rpm continuous cause thats what the motor was spinning.
70mph+ with my scooter on it, no vibration or other scary stuff.
It'll be fine!(famous last words...)


80mm shaft.
Same Sketchy_Racer as on the Simple Dyno forum?

[SwePatrick]

I'm just kinda getting the feeling a bidlot or athena barrel and some time on a dynojet would be a good starting point. From there he has a test engine he could put on his dyno and say 16hp equals. . . Adjust. Adjust. 16hp.

Right.

Biggest problem he has is his stubborness och not listening.
I have mentioned early in dyno build to put loadcell on the retarder.
But,, he seems finally to have figured that out by him self now. :)

And if doing that, and later setting up the loadcell as per instructions in his manual for yourdyno is a no brainer, a static pull will show correct power.
A sweep through the rpm band needs him to know the inertia on his whole dyno system and place that data into program.

[porttiming124]

I wonder if it's his goal to stretch the time rather than go straight to the point.

[Condyn]

It is his income so I would say dangling the carrot is definitely in the cards, but at the end of the day he is still developing things that nobody else is.

[wobbly]

The problem with the DynoJet baseline is that you are up against the ( in ) famous fudge factor built into the software.
There have been various attempts at calculating this , but its still just an estimate.
Doing proper calibration with a torque arm and known mass for the load cell is inherently super accurate , as is a stringline/dropping weight test with subsequent friction rundown, accurate for any inertia system.

Seems to me there is a huge mismatch between the retarders " power " capability and the engine , plus not having ( or not using ) a baseline PID loop setup for the power supply , means once again our friend is off on another tangent
that was never going to " work ".
That retarders inherent inertia seems well excessive to give a realistic run time for even the most powerfull 50cc engine , but having said that , gearing correctly can solve that issue.

I worked on the setup of a very expensive SuperFlow retarder control system for an Eddy Current dyno and it was a necessary "workaround " to use large switched resistor banks on the power supply, as it was technically impossible
to accurately control the dyno at low power numbers with sufficient resolution when testing a single cylinder mule engine - and then also using the same system to control the power produced by the completed test engine.
ie a delta factor of 4
As always the Devil is in the detail.

[lodgernz]

FOS software download link, valid until February 17, 2022

https://we.tl/t-A61fCirINx

I wrote these programs...

Frits, thank you for these gems.
I suspect your memory of their details might be hazy, but I'm going to ask anyway: In the squish program, what is the "number of crankshaft degrees"? Is it the exhaust open duration, or the EO point?
Or something else?

[TZ350]

.
Reminds me very much of New Zealand Bucket racers. Great ideas, build a dyno in the garage to test things, clever engineering solutions and lots of enthusiasm. Many world beating ideas tried but not every idea worked out. I like watching him work.

[Frits Overmars]

.
Reminds me very much of New Zealand Bucket racers. Great ideas, build a dyno in the garage to test things, clever engineering solutions and lots of enthusiasm. Many world beating ideas tried but not every idea worked out. I like watching him work.I like to watch the Two-Stroke Stuffing-videos too. I even like to think that from time to time Alex comes up with ideas I put into his mind, so he may be excused for making all the mistakes that I used to make. He is also adding a few of his own. Never mind, it will all lead to KISS-awareness :msn-wink:.
350694

[Frits Overmars]

Frits, thank you for these gems.
I suspect your memory of their details might be hazy, but I'm going to ask anyway: In the squish program, what is the "number of crankshaft degrees"? Is it the exhaust open duration, or the EO point? Or something else?It's the number of crankshaft degrees, and the number of calculation steps, from the start of the squish calculation until Top Dead Center. It should all become clear if you hit the L-key.

While we are on the subject, I prepared two List-screenshots. The first one looks like all the other Maximum Squish Velocity programs you can find on the internet.
I entered the Aprilia RSA-data of 0,7 mm squish clearance and 13000 rpm, but I ignored the dynamic stretch of about 1% of the stroke. The outcome is a maximum squish velocity of 64 m/s at 11° before TDC.
For the second screenshot I included the 1% dynamic stretch. Now the maximum squish velocity has skyrocketed to 144 m/s at 5° before TDC.

Some difference, isn't it? Need I say more about the usefulness of those other MSV-programs?
350696 350695

By the way: you cannot have too much squish velocity. You can have an ignition system that isn't up to it.

[F5 Dave]

My point was he needs a non experimental engine to set up his experimental dyno and see if it will actually give decent numbers over a reasonable range that replicates how the engine will be used.

[lodgernz]

It's the number of crankshaft degrees, and the number of calculation steps, from the start of the squish calculation until Top Dead Center. It should all become clear if you hit the L-key.



Thanks Frits.
I found that the program produces the same MSV no matter what crankshaft degrees I enter, so I'm still unsure how to use that parameter.

Also, one of the parameters is "squish centre gap". Is that the squish clearance at the inner edge of the squish band?

I'm surprised that the Exhaust timing is not a parameter. Wouldn't the starting point of the compression phase be important? What am I missing here?

[wobbly]

Frits is being clever , I think . The squish mid point gap allows for those deluded people who believe a tapered ( diverging ) squish is a good thing.
It isnt , but entering the average squish depth allows for this.
This deviates tho from something I think Neels wrote about that very point .From memory his logic was that with a taper , at the bore the velocity may be higher , but the lowest velocity is at the curtain area around the
bowl edge.
This is where it actually matters ie this is the point where the turbulence is created that increases the flame speed.

I was going to disagree with Frits statement that there is no such thing as too high MSV , as in many experements with squish width and depth it always seemed the best compromise
for MSV was around 40M/s - this being the number generated by the usuall programs that dont allow for rod stretch. Over that MSV level overev is always lost with a comensurate increase in mid power , but if you think about what the real world result is of high MSV is ie increased flame speed across the bowl , this equates directly to the same effect as an increase in spark advance ,
without the attending losses due to excess charge compression whilst its still starting to gain burn speed.

Thus its clear that increasing MSV , while retarding the spark advance where overev power loss begins , is a better power making compromise - very easy with a digital programmable ECU.
This must also overcome the downside of unburnt charge retention in a wide SAR , but if the piston is all but hitting the head , there is no charge retention to speak of.

Nowhere is this effect more evident than in KZ kart engines with a dumb , but easy to tech , straight line ignition.
Any less than 0.8mm squish depth , or any more than 35% SAR , and all the overev power dissapears ( past 14,000 ) - MSV 26.5 M/s
You can easily retard the static advance , to regain the lost power range , but then all the mid power is lost ( down at 10,000 )
As always , no free lunch.

[F5 Dave]

I came home for lunch today. I'm not sure if it was free, but the wife was very accommodating.

[Frits Overmars]

Thanks Frits.
I found that the program produces the same MSV no matter what crankshaft degrees I enter, so I'm still unsure how to use that parameter.
Also, one of the parameters is "squish centre gap". Is that the squish clearance at the inner edge of the squish band?
I'm surprised that the Exhaust timing is not a parameter. Wouldn't the starting point of the compression phase be important? What am I missing here?The number of crankshaft degrees determines how long the list is going to be, in case you wish to print it. The default value is from 20° before TDC to TDC, because that is the only zone where squish effects are going to play a role. But if you wish to see piston position, velocity and acceleration over a bigger part of the stroke, you can enter your desired number of crank degrees.

You are right about the squish centre gap.

The starting point of the compression phase makes me think of those geniuses who insist on using 'effective' versus geometric compression ratios although they have no way of knowing the pressure in the cylinder at the point of exhaust port closure because that strongly depends on what the pipe has been doing.
The squish velocity is independent of the gas density in the combustion chamber. The kinetic energy with which the squish flow blows the ionized molecules between the spark plug electrodes aside, is dependent of the gas density, but that is another story.

Come to think of it: that story deserves to be told, and it would fit right in.

An ignition system, trying to set a combustible mixture on fire, has three enemies: electrode gap width, squish turbulence and compression pressure (actually there are also some secondary enemies, like mixture strength and mixture purity, but we will leave that out for now).
The voltage, required to jump an electrode gap, is proportional to the gap width, like 10.000 Volts per millimeter or something like that.
The voltage between the electrodes ionizes the molecules in between, and once there is a complete path of ionized molecules, a current starts flowing: it sparks.

The problem with squish is that it blows away the ionized molecules, so it takes more voltage to initiate a spark. As I said earlier, you cannot have too much squish, but you can have an ignition that isn't up to it.

Above I said something about the required 10.000 Volt per mm gap. But that is in still, ambient air. If the air pressure rises, so does the resistance of the air between the electrodes.
An engine with a good cylinder filling may have a pressure of 30 bar between the electrodes by the time a spark is due.
An ignition that is not up to the job, may start playing havoc as soon as the engine comes into the power band and the compression end pressure in the combustion chamber rises. Combustion will suffer and the next compression cycle will yield a lower end pressure, so the ignition will function again. The power curve will look like a sawtooth graph.
If you suspect that your engine may be suffering in this way, there is a really simple way to find out: reduce the electrode gap to about 0,2 mm. It that helps, get a better ignition.

Below are two power curves from experiments with a 125 cc KZ kart engine back in 2010: one curve with the ignition system prescribed by the regulations (yes Wob, it was the same brand that you are still compelled to use today) and one with exactly the same engine, nothing changed, except I fitted a better ignition.
350700

PS: a dropping battery voltage in a battery ignition system makes itself noticed in the same way.
The engine will still run OK part-throttle, but when you give it full throttle, the compression pressure will rise and the engine will protest.

[lodgernz]

Thank you Frits and Wobbly. Great information as always.

[husaberg]

257539

Attached to the float bowl is a large adjustable needle jet purchased from a Model Shop.

What was that adjustable needle valve from Rob?

[philou]

350702350703350704

[TZ350]

What was that adjustable needle valve from Rob?

It was just an accessory something in a plastic bag with a lot of other things in bags on a rack at a model shop. No idea what make/model of engine it was for.

[Peter1962]

350702350703350704

some more pictures of the Laszlo Peres Maico

https://www.leguidevert.com/_lgv/img_forum/2011/12/154665_370_heute149a.jpg

https://www.leguidevert.com/_lgv/img_forum/2011/12/154665_994_maicop.jpg

https://www.leguidevert.com/_lgv/img_forum/2011/12/154665_370_heute149a.jpg

https://www.leguidevert.com/_lgv/img_forum/2011/12/154665_1114_heute140.jpg

https://www.leguidevert.com/_lgv/img_forum/2014/03/154665_2245_zweitakt-viertakt-mischung-010.jpg.1709151.jpg

https://www.leguidevert.com/_lgv/img_forum/2014/03/154665_2423_1256.jpg

https://www.leguidevert.com/_lgv/img_forum/2014/03/154665_2550_1258.jpg

http://www.eurospares.com/graphics/engine/fivestrokeengine3mrad068275.jpg

http://up.picr.de/9192015cnw.jpg

http://www.leguidevert.com/_lgv/img_forum/2014/03/154665_2369_1254.jpg

http://www.schotterfun.de/media/Pami/3-Takt.JPG

In this article you can read about the second prototype that he made, in 1983
https://www.motorradonline.de/modern-classic/auf-achse-zwei-viertakt-konzept-mitbegruender-der-bmw-r-80-g-s-bewies-tueftler-qualitaeten/

[philou]

What was that adjustable needle valve from Rob?


dellorto offers one

350708
350709350710

[F5 Dave]

Oh good lord Peter, that looks like Heresy. Burn it.

[andreas]

In the editing room:
-What is diesen Maico, how many takts it got?
Bruno? -Vier, because of the nockenvelle.
Klaus? - Zwei, It fires every revolution.
Well, nockenvelle counts for at least one, must be it's a dreitakter.

[Flettner]

Finally got the aulternator sorted, 14.1V continuous.
Time to find another trail ride, tuning time.

[TZ350]

.

350714

Starting to get there, supercharged nitro 50cc 11hp @ 8k rpm. https://youtu.be/hKaGf_9yMLU

Our Team ESE RG50's need 14k rpm to get 11hp. Sure looking forward to when 2Stroke Stuffing gets his bike running consistently.

[SwePatrick]

.

350714

Starting to get there, supercharged nitro 50cc 11hp @ 8k rpm. https://youtu.be/hKaGf_9yMLU

Our Team ESE RG50's need 14k rpm to get 11hp. Sure looking forward to when 2Stroke Stuffing gets his bike running consistently.

Don´t trust the numbers, a lot of noise and the sensor was calibrated high.
But yes, it will produce quite high numbers at lower rpm compared to a 'piped' engine.
It might never get a big peak later in rpm band thou, just because there isn´t any more breathing than the superchargers capacity.

[Flettner]

Edited....

[andreas]

Indeed. Maybe it can also be an "inverted" type, where the induction happens through the valves, and exhaust at ports in the cylinder. That way it can still have a good pipe.
Talking about the uniflow.

[ken seeber]

Indeed. Maybe it can also be an "inverted" type, where the induction happens through the valves, and exhaust at ports in the cylinder. That way it can still have a good pipe.
Talking about the uniflow.

My suggestion to Alex was to raise the transfers to above the exh port height. Yes there will be blowback into the transfers, albeit resisted by the blower pressure, but it will give the engine the opportunity to supercharge during the "blowup" period , as opposed to the blowdown period. Maybe the pipe will still work as well.

Blowup is still optional or even inevitable though.

[andreas]

At this point I've lost the understanding for what he is trying to do. The uniflow achieved everyting he is after- almost a century ago.

[SwePatrick]

My suggestion to Alex was to raise the transfers to above the exh port height. Yes there will be blowback into the transfers,

It will demand a LOT of pressure from the supercharger to overcome the blowdownpressure(who want´s to blow down into crankcase)
Pressure that high isn´t aviable from that supercharger.
He needs helix lobes and teflonstripe it.
And,, it gets very hard to drive.

[Vannik]

A supercharger like Alex is using is very inefficient and not capable of much pressure if I have his model right. This is its map:

350715

[Frits Overmars]

My suggestion to Alex was to raise the transfers to above the exh port height.... it will give the engine the opportunity to supercharge during the "blowup" period...Alex has got that covered with his rotary exhaust disc, that closes the exhaust before the transfers, so there is no 'blowup' phase.

[husaberg]

A supercharger like Alex is using is very inefficient and not capable of much pressure if I have his model right. This is its map:

350715

I suspect they have Teflon tips and melt before 2 bar. like the Toyota used to.
Roots blowers are inefficient esp with regards to heat compared to screw blowers, but are cheap and cheerful

From memory, on the GM diesels they were only used to scavenge and later turbo was used to give a HP boost and likely make it quieter.
The AMR are 300cc per rotation run to about 14k
i would suspect that's enough flow for north of 45hp.
not sure what it would take to run one though.
but with a AC clutch and a IHI RHb31 it would be pretty spectacular.
there is a slighly bigger AMR500 but surely that's too big?

[speedpro]

I have an AMR300. they are plain jane, no fancy teflon in these babies. Ex suzuki Cappucino

[ken seeber]

Alex has got that covered with his rotary exhaust disc, that closes the exhaust before the transfers, so there is no 'blowup' phase.

Frits, it was a suggestion of some time ago when there was some discussion on the rotary exh valve and perhaps its potential durability.

I understand the comments on the efficiency of the selected blower, but when he gets it running properly then time will be the judge.

More to come...

[Vannik]

Frits, it was a suggestion of some time ago when there was some discussion on the rotary exh valve and perhaps its potential durability.

I understand the comments on the efficiency of the selected blower, but when he gets it running properly then time will be the judge.

More to come...

I know it is easy from a distance but from running a lot of simulations and tests on a land speed bike with a supercharger we learnt a few things. The hunting phenomena which is blamed on fuel starvation is in all probability the high cylinder pressure when it makes power preventing the full inflow of inlet gas leading to a pressurized inlet system, then the power drops, the inlet system discharges and the power climbs again. To be repeated again.

[Pursang]

I know it is easy from a distance but from running a lot of simulations and tests on a land speed bike with a supercharger we learnt a few things. The hunting phenomena which is blamed on fuel starvation is in all probability the high cylinder pressure when it makes power preventing the full inflow of inlet gas leading to a pressurized inlet system, then the power drops, the inlet system discharges and the power climbs again. To be repeated again.

So, Blow-down capability (STA) is still a major factor in determining the power output, no matter how much inlet and transfer potential is provided!

[husaberg]

I have an AMR300. they are plain jane, no fancy teflon in these babies. Ex suzuki Cappucino

No idea google suggests early was uncoated and later it seems were "fluorine resin coated. ."
No idea what the heck that is or if its crap or gospel?

I was only going off what used to happen on the MR2 superchargers when they were speeding up in regards to not running the boost too high.

edit if it does have it It seems to be a plastic coating Mazda made for the wankel.
https://patents.justia.com/patent/4645440


later looks like a similar product to Telflon?
https://www.sciencedirect.com/topics/chemical-engineering/fluorine-containing-polymer
https://www.gunze.co.jp/e/epd/aboutfluoride/

Fluorine resin can be used to various applications like non-stick frying pan, semiconductor, OA equipment, automobiles and general industrial machinery, has been active in a wide range of fields.


https://www.drilube.co.jp/english/product/fluorine.html
In addition, fluorine resin has various chemical resistance, corrosion resistance, heat resistance and electrical insulation properties.
The coefficient of friction of DRILUBE® products containing fluorine resin is in the range of 0.03-0.1. Products utilizing this low frictional property demonstrate excellent lubrication under light load conditions, and a stable sliding performance can also be expected.
DRILUBE® products containing fluorine resin, and utilizing the property of non-cohesion with fluorine resin, can be applied to mold release uses.
DRILUBE® products containing fluorine resin are currently being used in various industrial fields.


Its the net who knows whats real or fake queues


https://www.youtube.com/watch?v=kRY0SbDO-sY

[pete376403]

No idea google suggests early was uncoated and later it seems were "fluorine resin coated. ."
No idea what the heck that is or if its crap or gospel?

I was only going off what used to happen on the MR2 superchargers when they were speeding up in regards to not run the boost too high.

edit if it does have it It seems to be a plastic coating Mazda made for the wankel.
https://patents.justia.com/patent/4645440


later looks like a similar product to Telflon?
https://www.sciencedirect.com/topics/chemical-engineering/fluorine-containing-polymer
https://www.gunze.co.jp/e/epd/aboutfluoride/



Its the net who knows whats real or fake queues

PTFE Polytetrafluoroethylene is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The commonly known brand name of PTFE-based compositions is Teflon by Chemours, a spin-off from DuPont, which originally discovered the compound in 1938.
So it looks like there is fluorine of some sort in there

(message says this is too short and wants 10 characters?)

[Flettner]

In my supercharged Honda 100 I cut dovetails in the tips of the rotors, and slid in a teflon type tip seal. Helped with the delivery pressure for sure. The teflon strip was given to me by some drag racer, a common upgrade.

[philou]

Husqvarna prototyp

350716350717350718

[Frank S.]

Husqvarna prototyp


For those who change their crankshafts frequently :clap:

[Peter1962]

Husqvarna prototyp

350716350717350718


Some very clever ideas in that design !

[Ocean1]

In my supercharged Honda 100 I cut dovetails in the tips of the rotors, and slid in a teflon type tip seal. Helped with the delivery pressure for sure. The teflon strip was given to me by some drag racer, a common upgrade.

I've used teflon round bar before now, worked just as well.
Doesn't help with end clearances though, which is just as much of a problem.
In the end what works best is the same solution that works for the engine: there's no substitute for cubic inches.

[SwePatrick]

I suspect they have Teflon tips and melt before 2 bar. like the Toyota used to.
Roots blowers are inefficient esp with regards to heat compared to screw blowers, but are cheap and cheerful

From memory, on the GM diesels they were only used to scavenge and later turbo was used to give a HP boost and likely make it quieter.
The AMR are 300cc per rotation run to about 14k
i would suspect that's enough flow for north of 45hp.
not sure what it would take to run one though.
but with a AC clutch and a IHI RHb31 it would be pretty spectacular.
there is a slighly bigger AMR500 but surely that's too big?


Don´t forget Alex is running the supercharger 'wet' and by that got lubrication for the seals.
And for Vannik:effiency might rise some when running it wet as the oil seals it up some, not a whole lot thou.

[Vannik]

Don´t forget Alex is running the supercharger 'wet' and by that got lubrication for the seals.
And for Vannik:effiency might rise some when running it wet as the oil seals it up some, not a whole lot thou.

It is not the mechanical efficiency I worry about but the thermal one. The manufacturer only characterize it to 1.8bar while Alex wants to run much higher. Just extrapolating the curves to 3bar will already heat the air to well over 300degC if it can reach that and absorb lots of power. Hopefully I am wrong...

[Frank S.]

Just extrapolating the curves to 3bar will already heat the air to well over 300degC if it can reach that and absorb lots of power. Hopefully I am wrong...

An Intercooler might help

[Flettner]

Heat and methanol, symbiotic relationship.

[Grumph]

I've used teflon round bar before now, worked just as well.
Doesn't help with end clearances though, which is just as much of a problem.
In the end what works best is the same solution that works for the engine: there's no substitute for cubic inches.


Heat and methanol, symbiotic relationship.

Yes and yes. Our locally made "Martin" roots blower used a teflon rubbing strip on the tips of the rotors - but we finished up having to trim about .015in off each end of the rotors due to growth when hot. Only lost 2PSI though.
The main problem historically with roots type though is churning which is a great heat source. Ours had division bars on inlet and output shaped to occupy wasted volume between the rotors. Talking to the guy who designed and developed them, he'd tested them to around 18,000 rpm - bolted to his lathe with a datsun gearbox used as a stepup for rpm. Reckoned they were 80% efficient to about 10,000 rpm but dropped off after that.
We were able to tell him ours didn't drop off boost up to 15,000rpm.

Anything above about 1.5bar you should really look at running a second blower in series - 2 stage blowing. The mathematics of it were proved before WW2.

[Grumph]

So, Blow-down capability (STA) is still a major factor in determining the power output, no matter how much inlet and transfer potential is provided!


My experience is with blown 4 strokes - but yes, if you haven't got enough exhaust duration and flow volume you will hit a wall.

As a side note, I was told by a very experienced - and qualified - engineer, don't try and run a tuned pipe with a blower. Forget returning charge - all you want to do is empty the cylinder as quickly as possible. Let the blower do the work.

[lohring]

The successful way to supercharge a two stroke is to raise the exhaust pressure along with the intake pressure. This was done a long time ago with the Napier Nomad (https://en.wikipedia.org/wiki/Napier_Nomad). Today snowmobiles use a turbocharger after the tuned pipe to do the same thing. The engine pictured below is an extreme example that developed around 800 hp with nitrous injection.

Lohring Miller

350723350724

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/to8E43_456M" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Adding Boost .......

[OopsClunkThud]

glad he's finally added a chain guard

[Flettner]

In door dyno soon, or at least an under cover one.
A major step forward, dyno time, rain hail or shine and I can leave the bike set up for week or months if need be.

[Flettner]

glad he's finally added a chain guard

Safety shmafety, .... 😁

[husaberg]

One thing i picked up from Allen Millyard videos is to put grinders and other dust makers out undercover out of the shop in a lean-to just like that.
Also having it in a cell like that will mean you can potentially line it to keep the noise down for her indoors or them's next doors.
or funnel it directly at the dude that mows his lawns at 7.30am on Sundays.

[F5 Dave]

Wood? Where did you get Wood from?


But seriously, leave fire extinguisher by the exit door.

[Flettner]

Wood? Where did you get Wood from?


But seriously, leave fire extinguisher by the exit door.

Dyno, I always have the extinguisher handy, I dont like sudden unexpected fires.

Wood, yes harder to get these days. The 2 x 8 was dear enough, the poles I bought a couple of years ago on special, all keen and everything...... but nothing happened until now.
Im looking forward to having the dyno set up properly and permantly, under cover.

[PVO]

I'm working on varying snow bike layouts and engine architectures, some of which, the power being transmitted from the engine through a CVT system would need to change by 90 degrees in order to get the power from the shaft the driven clutch resides on to the driveshaft of the track. The two solutions I'm interested in are a pair of bevel gears and using a drive belt that changes the rotational axis of the shaft by 90 degrees. Power output is planned to be in the range of 160 - 240hp. I have zero experience with either type of drive and was wondering if anyone has technical expertise or reference material for either design approach? A twisted belt approach would be preferred since it would be cheaper and lighter to make, however, the bevel gear arrangement could also be made to work and may package better. I'm seeking a better understanding of the feasibility of the twisted belt and how to estimate power loss through each configuration.

350729

350730

[husaberg]

I'm working on varying snow bike layouts and engine architectures, some of which, the power being transmitted from the engine through a CVT system would need to change by 90 degrees in order to get the power from the shaft the driven clutch resides on to the driveshaft of the track. The two solutions I'm interested in are a pair of bevel gears and using a drive belt that changes the rotational axis of the shaft by 90 degrees. Power output is planned to be in the range of 160 - 240hp. I have zero experience with either type of drive and was wondering if anyone has technical expertise or reference material for either design approach? A twisted belt approach would be preferred since it would be cheaper and lighter to make, however, the bevel gear arrangement could also be made to work and may package better. I'm seeking a better understanding of the feasibility of the twisted belt and how to estimate power loss through each configuration.

350729

350730

Car diffs have bevel gears KISS.
Slasher Mowers run space-efficient 90-degree boxes or just the gearing in the hp ranges you want.
they will weigh more then the belt approach
FleTtner designs and builds transmissions for Gyros
For pre made and lightweight i would uses an output bevel gearbox of a CRV or smiiar FWD awd
https://trademe.tmcdn.co.nz/photoserver/plus/1402335681.jpg
https://jdmofsandiego.com/wp-content/uploads/2020/11/K-SERIES-AWD-MT-TRANSMISSION1-scaled.jpg
https://dsportmag.com/wp-content/uploads/159-006-Feat-CasasCivic-Transmission.jpg

[Ocean1]

put grinders and other dust makers out undercover out of the shop in a lean-to just like that.

I can't do that yet, and any sort of partition means I can't handle full lengths of steel. It's a constant battle trying to keep grinding dust away from the machine shop area.
It's surprisingly nasty shit, not just highly abrasive, it gets into anything electronic and kills it dead, cellphones included.

New workshop on the way, will try to manage it better there. Big fuckoff suckymotor maybe.

[Grumph]

I can't do that yet, and any sort of partition means I can't handle full lengths of steel. It's a constant battle trying to keep grinding dust away from the machine shop area.
It's surprisingly nasty shit, not just highly abrasive, it gets into anything electronic and kills it dead, cellphones included.

New workshop on the way, will try to manage it better there. Big fuckoff suckymotor maybe.


Other way around. Machinery area at a positive pressure, maybe 1 -2 psi above grinding/dusty area and the dust won't come in.
That's the easiest way to do a clean room. Needs good doors though.

[ken seeber]

Other way around. Machinery area at a positive pressure, maybe 1 -2 psi above grinding/dusty area and the dust won't come in.
That's the easiest way to do a clean room. Needs good doors though.

Over here in the west of Oz where the climate is relatively dry, approx 25% of all houses are fitted with an evaporative cooler, sometimes known as swampies Work reasonably well until it gets humid.
Typically these, I think, are sized to provide around 30 air changes per room per hour. Something like this would be pretty useful to keep the m/c shop are cooled with, of course, sensible divisions and air paths.
Dunno if ewe lot have them over the ditch.
350733

[husaberg]

I can't do that yet, and any sort of partition means I can't handle full lengths of steel. It's a constant battle trying to keep grinding dust away from the machine shop area.
It's surprisingly nasty shit, not just highly abrasive, it gets into anything electronic and kills it dead, cellphones included.

New workshop on the way, will try to manage it better there. Big fuckoff suckymotor maybe.


Other way around. Machinery area at a positive pressure, maybe 1 -2 psi above grinding/dusty area and the dust won't come in.
That's the easiest way to do a clean room. Needs good doors though.

Sorry i said Milyards it was Paul brodie
Who you will know of Greg but you might not have seen his videos.

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


https://i.imgur.com/lgszxDb.mp4


Over here in the west of Oz where the climate is relatively dry, approx 25% of all houses are fitted with an evaporative cooler, sometimes known as swampies Work reasonably well until it gets humid.
Typically these, I think, are sized to provide around 30 air changes per room per hour. Something like this would be pretty useful to keep the m/c shop are cooled with, of course, sensible divisions and air paths.
Dunno if ewe lot have them over the ditch.
350733
i thought the western oz way was to spray water direct on the tin roof. "redneck air con"
We do that with dairy sheds of over here its 45c plus in the middle of summer at Cow height, on a 30-degree day as each Bovis is 2kw each and the uninsulated roof just seems to superheat it.

ps a swampy just a water cooler Cupola?
https://www.valleyforgecupolas.com/uploads/5/7/2/9/57296727/vfc-feb-20_orig.jpg

[wax]

I Know its probably be done to death but I cant find it in here.
I under stand squish should be set that the piston hit the head 1000 rpm higher than you will ever see. You cant deto whats not there right.
What about squish band width/ratio. Is there a magic number that works best ? On a dome piston should you match the squish to the piston shape/dome with of course a small angle towards the combustion chamber. What should the angle be to over the piston angle
thanks guys

[Frits Overmars]

I Know its probably be done to death but I cant find it in here.
I under stand squish should be set that the piston hit the head 1000 rpm higher than you will ever see. You cant deto whats not there right.
What about squish band width/ratio. Is there a magic number that works best ? On a dome piston should you match the squish to the piston shape/dome with of course a small angle towards the combustion chamber. What should the angle be to over the piston angle
thanks guysA squish band area ratio of 50% is a good general value. Wobbly may be kind enough to explain in more detail why that percentage is smaller on engines with a fixed ignition timing.
Forget about your 'small angle towards the combustion chamber'. The angle of the squish area should exactly match the piston crown, so use a domed squish band on a domed piston.

[wax]

A squish band area ratio of 50% is a good general value. Wobbly may be kind enough to explain in more detail why that percentage is smaller on engines with a fixed ignition timing.
Forget about your 'small angle towards the combustion chamber'. The angle of the squish area should exactly match the piston crown, so use a domed squish band on a domed piston.
Thanks very much
I did chop a piston in half then scanned it and fired it into cad so i could get the measurement perfectly
From here I will 3d print and then it will show me how good i was.
Im reading that a bath tub is a good shape on a dome piston so I will go with that,
These are to go into and existing head and so its becoming hard to get enough length into the spark plug to get the distance I need off the top of the piston.
The old dome was a hemi style with the dome 15mm off the top of the piston with a straight cut squish that really wasn't one

[wobbly]

The basics you have the good info so far.
50% SAR with closest safe squish depth is generally the best place to start.
Conventional wisdom is that a bathtub works on a dome , this was initiated into the common knowledge base by Jan's experiments at Aprilia and I do know he tried a flat top
without any gain.
But this is not the case with a conical dome , and the narrow squish as is used in KZ kart engines.

I did some serious tests in the early 2000's with the conical shaped domed pistons .
At the time a 7* conic was the std shape and the tech rules were ( are ) a strict 13cc to the top of the plug hole.
Several GP teams were using toroidal shapes , especially after unleaded was mandated ( that word again ) to help prevent deto that was all but impossible with Elf Mitso 130 octane rocket fuel.

But A work around the CIK rules , that would normally prevent using a toroid in KZ , was to drill a tiny hole at an angle from the toroids highest point into the plug threads to allow trapped air to escape.
This proved to tech that the chamber volume was legal , when using the simple method of filling to the top of the threads with the piston at TDC.
With the toroid , and the plug ground electrode 4 mm from the top of the dome , this was worth on average 1.5 Hp with a huge gain in deto resistance - allowing much leaner mixtures to be used.
Sadly not long after I started doing this , the CIK instituted a new screw in plug gauge that had exactly 2cc volume , thus preventing the " work around " of a drilling.

The need for a very narrow , and slightly diverging , squish when using a straight line ignition , is that the actual effect of proper squish geometry is to eject high speed turbulent eddies into the
smoothly advancing combustion flame front - and this dramatically increases the speed of the expanding " bubble " of burning A/F mixture.
Thus the time needed around TDC for the combustion to be completed , is reduced - and this effect is exactly analogous to advancing the ignition timing.

In a KZ the static spark advance is a serious compromise between generating sufficient mid power Vs preventing deto in the area between peak torque and peak Hp.
A side effect is that retarding the static advance allows greater overev as well.
So , without the luxury of a proper digital , retarding ignition system , it becomes impossible to generate the power needed at low rpm , as well as achieving overev power when an efficient squish is used.

It appears that Honda and Yamaha were convinced a toroid is the best for a flat top , as all of their "fast " engines used this, and I have proven it works best on a conic.
And based on that , I believe a toroid , in most 2T tuned engines is the best choice .

This was reinforced by another test done for a customer who revived , then remarketed the air cooled Webco head design used on old Yamaha singles and twins.
I back to back tested a normal stock configuration hemispherical , vs a bathtub , vs a toroid . These were all CNC machined with the exactly same squish and cc on a domed piston.
The result was a clear win to the toroid with an average of + 4 RWHp ( in a 250 twin ) , and the bathtub was exactly in the middle with +2 Hp average.
But the real kicker was that the toroid then allowed an extra 2* of static advance to be safely wound in , gaining another + 2Hp with no deto issues at all.
The result was much , much more dramatic when running higher compression for the common 110 octane race fuels available, and allowed in USA.

[wax]

The basics you have the good info so far.
50% SAR with closest safe squish depth is generally the best place to start.
Conventional wisdom is that a bathtub works on a dome , this was initiated into the common knowledge base by Jan's experiments at Aprilia and I do know he tried a flat top
without any gain.
But this is not the case with a conical dome , and the narrow squish as is used in KZ kart engines.

I did some serious tests in the early 2000's with the conical shaped domed pistons .
At the time a 7* conic was the std shape and the tech rules were ( are ) a strict 13cc to the top of the plug hole.
Several GP teams were using toroidal shapes , especially after unleaded was mandated ( that word again ) to help prevent deto that was all but impossible with Elf Mitso 130 octane rocket fuel.

But A work around the CIK rules , that would normally prevent using a toroid in KZ , was to drill a tiny hole at an angle from the toroids highest point into the plug threads to allow trapped air to escape.
This proved to tech that the chamber volume was legal , when using the simple method of filling to the top of the threads with the piston at TDC.
With the toroid , and the plug ground electrode 4 mm from the top of the dome , this was worth on average 1.5 Hp with a huge gain in deto resistance - allowing much leaner mixtures to be used.
Sadly not long after I started doing this , the CIK instituted a new screw in plug gauge that had exactly 2cc volume , thus preventing the " work around " of a drilling.

The need for a very narrow , and slightly diverging , squish when using a straight line ignition , is that the actual effect of proper squish geometry is to eject high speed turbulent eddies into the
smoothly advancing combustion flame front - and this dramatically increases the speed of the expanding " bubble " of burning A/F mixture.
Thus the time needed around TDC for the combustion to be completed , is reduced - and this effect is exactly analogous to advancing the ignition timing.

In a KZ the static spark advance is a serious compromise between generating sufficient mid power Vs preventing deto in the area between peak torque and peak Hp.
A side effect is that retarding the static advance allows greater overev as well.
So , without the luxury of a proper digital , retarding ignition system , it becomes impossible to generate the power needed at low rpm , as well as achieving overev power when an efficient squish is used.

It appears that Honda and Yamaha were convinced a toroid is the best for a flat top , as all of their "fast " engines used this, and I have proven it works best on a conic.
And based on that , I believe a toroid , in most 2T tuned engines is the best choice .

This was reinforced by another test done for a customer who revived , then remarketed the air cooled Webco head design used on old Yamaha singles and twins.
I back to back tested a normal stock configuration hemispherical , vs a bathtub , vs a toroid . These were all CNC machined with the exactly same squish and cc on a domed piston.
The result was a clear win to the toroid with an average of + 4 RWHp ( in a 250 twin ) , and the bathtub was exactly in the middle with +2 Hp average.
But the real kicker was that the toroid then allowed an extra 2* of static advance to be safely wound in , gaining another + 2Hp with no deto issues at all.
The result was much , much more dramatic when running higher compression for the common 110 octane race fuels available, and allowed in USA.
Thanks again Wobbly.
This is where i am at the moment. The squish has the perfect curve to the dome of the piston. The design of the head the dome is going into make it’s hard to get the plug down far enough. I’m thinking I will have to go to long reach plugs im at 19mm on this plug but it’s not enough. This is a dome I trying to produce for the masses and so I can’t be using an expensive race plug.
350734

[wobbly]

Move the top o ring down onto the horizontal face - means the spigot can be shortened to nothing if need be.
Also add a thread cooling slot , you can make it say 6 radial pockets with support bridges if you are concerned with strength , but as the cover supports the plug boss its probably not needed.

[husaberg]

Move the top o ring down onto the horizontal face - means the spigot can be shortened to nothing if need be.
Also add a thread cooling slot , you can make it say 6 radial pockets with support bridges if you are concerned with strength , but as the cover supports the plug boss its probably not needed.

As an aside, i would go with the one piece and make it out of Aluminum.;)

[F5 Dave]

Are you feckin kidding? Blue is Cool. Might want to make it fully round though. I can see you losing a lot of compression as is.

[koenich]

Move the top o ring down onto the horizontal face - means the spigot can be shortened to nothing if need be.
Also add a thread cooling slot , you can make it say 6 radial pockets with support bridges if you are concerned with strength , but as the cover supports the plug boss its probably not needed.
As always, thanks for sharing the knowledge!

Any rule of thumb to design the toroid? There are quite a few ways to achieve compression xy...
- squish area is clear
- h1 depth of spark plug
- h2 height of bowl
- r1 radius starting at squish area
- r2 radius transferring from r1 to spark plug
If r1 starts normal to end of squish area the radius is given by the height of the bowl...plus is r1 = r2?

350739

[wax]

Are you feckin kidding? Blue is Cool. Might want to make it fully round though. I can see you losing a lot of compression as is.
Its a 125 so only half a real engine, This is why i only went for half a dome
the blue is because its a yamaha

[wobbly]

General design comments are that R1 isnt. Its straight @ 60* for about 1/2 H2.
H1 can be varied but I make it such that the ground electrode is around 4mm- 6mm from the dome ( compression dependent ), with the plug body flush.
The flat diameter around the thread end should be a minimum of 17mm or the alloy overheats locally due to no threads on the plug end.

Originally NGK's spec for the old B10EGV type plug was that the unthreaded end should protrude 1.5mm into the chamber.
But im not sure if this is the case now with the latest plugs , and anyway this is specifically not allowed in KZ tech rules , so I havnt done any testing there.
Except I milled the end off a R7232A on a rotary table , the longer plug used in Honda's with the under plug deto sensor , such that the body was flush per the rules , but the ground electrode
was sticking well into the chamber on a small unmachined upstand - made no more power , bugger it.

[SwePatrick]

It is not the mechanical efficiency I worry about but the thermal one. The manufacturer only characterize it to 1.8bar while Alex wants to run much higher. Just extrapolating the curves to 3bar will already heat the air to well over 300degC if it can reach that and absorb lots of power. Hopefully I am wrong...

The thermal rises also if the mechanical seal get better.
Less 'slip n slide' for the air around the lobes makes for colder air.
But in alex case, the high boostnumbers we saw is a fruit of having the piston make a secondary compression of the air in the crankcase.

And i saw some other guy talked about coated rotors, coating will most certanly be destroyed by the fuel.
Autorotor(lysholm) said long ago that you should run no fuel into their supercharger due to coating couldn´t take it.

Teflonstriped as in big fuel classes(and more) in dragracing is the way to go, but needs service, and should never be ran dry.

[lodgernz]

Many times, Wobbly has talked about the dangers of using old fuel that has lost significant amounts of aromatics, and the risks of associated engine damage.

This is a video I took at a recent Ruapuna meeting.
A 4T bucket that is fast enough to beat the best 150 2T, with a matt black tank, sitting in full sun.

Perhaps the lack of aromatics isn't such a huge risk for a 4T, I don't know, but as 2T people, we need to know about this.


https://youtu.be/OWo7OVI6pHQ

[wobbly]

Yes , fuel conservation is a pet fetish of mine.
I cant imagine the number of destroyed pistons/cylinders I have seen that simply would not have happened with fresh fuel.

Anyone I work with in karts or bikes knows rule 1A , all fuel must be stored in 5L containers , with no air space, then mixed and used one at a time.
A 20L pail or a fuel tank left 1/2 empty overnight will degrade from 98 pump unleaded to 91, if you are lucky.

The instant any container is opened the Reid Vapour Pressure that has flashed off the light aromatics into the empty space , will blow out and disappear to atmosphere.
Then the lack of finely atomized fuel droplets that burn quickly in the A/F mix , makes the egt drop ( falsely ) as the big blobs of low octane fuel don't burn ,and as soon as you lean down you deto
if lucky , or seize if not.

When tuned to the edge of deto at all times this is super important for jetting repeatability, where 1 jet too conservative means you may miss pole by 2/1000 of a sec.

Maybe most 4T engines are running such low bmep they are nowhere near the edge of destruction , and this is not such of an issue.

[F5 Dave]

One of my dirtbikes has been sitting almost a year. I might need to drain the gas into the van. Good upper cylinder lubricant. Who know what I'll do with it when I upgrade to fuel injection carrier.

Wonder what people think when they used to follow me smelling of Av Gas and synthetic.

[PVO]

Hi everyone, I'm seeking clarification on a few aspects of crankshaft design and hoping for some input. Another member graciously shared some empirical numbers with me from his twin-cylinder engine and I wanted to get a feel for the analytical side too.


Crank Web Material Required to Support Press Fit Pin - Many pages back Frits noted a good rule of thumb to use for supporting the press-fit of the big end pin is around 1/2 the diameter of the crankpin. A press-fit assembly is relatively simple to set up in an FEA. Is it accurate to believe that if the press fit is FEA'd and there is no yielding of the crank web material around the pin, then there is sufficient material around the pin or are there other considerations I haven't accounted for?
350750
Big End Pin Engagement - Is there a similar rule of thumb for determining how much big end pin engagement is required?
350751
Crankshaft Stiffness and Deflection - If the crankshaft could be loaded and simulated in FEA is there a threshold for the amount of permissible deflection? Presumably, this number would be minimal, 0.025mm (0.001")?
Target Interference Fit - Does the amount of interference fit scale with output power or is it relatively constant across engine size/power output?

The engine I'm working on is an 850cc 90-degree twin (targeting 160hp NA and more later on with boost). Of the many design considerations two of the most critical will be sizing the big end pin and deciding on the crank architecture - no center bearing (like as drawn) or integrating a center bearing.

Husaberg - thank you for your input and ideas on converting the rotational axis. I think I've found a layout that won't require too much complication.

Thanks all for reading!

[Niels Abildgaard]

The engine I'm working on is an 850cc 90-degree twin (targeting 160hp NA and more later on with boost). Of the many design considerations two of the most critical will be sizing the big end pin and deciding on the crank architecture - no center bearing (like as drawn) or integrating a center bearing.



Thanks all for reading!

What engine type will be donor for cylinders,pistons and conrods?

[philou]

Scavening cylinder 125 italkit for Aprilia 125 RS

Radial angle 0°

350754

[wobbly]

The A port front wall is nowhere near angled back enough - it will short circuit badly with a good pipe.
Also no hook on the B port rear wall - doesn't seem very clever at all to me.

[Tim Ey]

Has anyone ever measured the pressure drop over the water circuit of a 125cc race engine? And also water flow would be interesting.
Regards Tim

[philou]

it was indicated 50 liters per minute for the rsa.

taking 1 litre/minute per cv seems relevant

the improvement in performance and adjustments allowed by the cooling, must compensate for the losses caused by the turbine of the water pump.

size the impeller and volute and a job.

[Frits Overmars]

it was indicated 50 liters per minute for the rsa.... Taking 1 litre/minute per cv seems relevant.I seem to remember it was 60 liters per minute for the RSA. 1 liter per minute per crankshaft hp is a good rule of thumb.

[philou]

following the ignition on ignition SEM rotax 123.

the problem is that there are 2 magnets side by side passing in front of the internal sensor.

with the oscilloscope, have noted the 2 top.


350756

ignitech sent me a specific configuration file.

the point of advance becomes completely crazy from 4000 revolutions.

with the oscilloscope, have noted that there are 2 sparks produced by the 2 magnets

350757

[PVO]

What engine type will be donor for cylinders,pistons and conrods?

850 Rotax Etec piston/small end assembly. I intend on making my own cylinders and rods.

[husaberg]

850 Rotax Etec piston/small end assembly. I intend on making my own cylinders and rods.

May i ask why your own rods?

[Niels Abildgaard]

850 Rotax Etec piston/small end assembly. I intend on making my own cylinders and rods.

Very,very interesting that 850 Etec thing
What advantage do You expect going from stock inline to own V2?
Do You have acces to parts for rough measurements or photos?

[Javier Ruda]

Also no hook on the B port rear wall - doesn't seem very clever at all to me.

Hello wobbly, on the Rotax 122 I am widening the b-port to the rear. How should the b-port hook be like? Is it for no interfering c-port flow?

[wobbly]

The B port hooks should intersect the centerline between 1/3 and 1/2 way from the boost port face to the bore center.
With a radius in the corner around 1/2 the depth of the hook.
Depends on how the other ports are arranged.
If you take a cylinder with a hook and run a stream down the duct by holding it upside down under a water tap , you will see the exiting flow is rotated axially , this clears exhaust residuals
from a large area in front of the boost port at BDC.
The C port flow is angled steeply and is attached to the rear wall , thus its not simply a matter of the B port flow being directed away from this exiting column.

[Javier Ruda]

Thank you wobbly! Very clear, I’ll do that hook. 👍

[philou]

piston with the ring lug at the rear.
with the original piston, you will very quickly be limited

[Javier Ruda]

piston with the ring lug at the rear.
with the original piston, you will very quickly be limited

Merci philou, I remember that. The issue is that I have an oversize piston (54.25 mm) and there is no 1-ring version available.

But I already bought a standard size 2nd hand cylinder, so next time it will be 1-ring type.

[philou]

position of the ring pin in relation to the transfert port


350767

[TZ350]

.
Team ESE exploring the possibility of fitting a Suzuki GP125 rotary valve assembly to a Suzuki RG50.

Also in the works is a small turbocharger with a much lighter bespoke 6061 aluminum exhaust turbine housing for turbocharging a 70cc two stroke. Aluminum should be Ok for the turbine housing as the exhaust gas is much cooler on a two stroke than a four stroke. We also want to make bespoke turbine housings so we can get the A/R ratio more suited to the capacity of the engine.

A rotary valve converted RG50 with an over bored turbocharged 70cc water cooled cylinder. With the turbo we plan on a draw through carb, but I am also tempted to fuel inject it directly into the turbo intake or maybe just after the turbo on the discharge side.

350769

[F5 Dave]

Nice collection of potential projects there Rob.

Some (long) while ago I was looking at spare RG cases and thinking "hmm. V-Twin"
Never happen now but,

[ken seeber]

Nice collection of potential projects there Rob.

Some (long) while ago I was looking at spare RG cases and thinking "hmm. V-Twin"
Never happen now but,

Can you guys still find suitable 100 cc 2 stroke bikes to make buckets from? Any over here are rare and sort of valued and held onto by collector types. Maybe you can get them from SE Asian countries I guess.

I often think that the bucket class could include 125 TAG kart engines. Using their clutch driving thru a jackshaft to attain the reduction required, meaning a single gear ratio. Could have them standard as per their karting homologation rules or also have a modified class as well.

Anyways, just a thought from someone 5000 km away.

[F5 Dave]

As an increasing old man exhausted from riding my Beta today I have to say racing looks increasing expensive and unappealing.

I bought a $1300 RS125 with 2 years supply of tyres, sold the engine for $600, instant $500 chassis. Circa 1990.

But I don't know what I'd do if I re entered as an old man trying to emulate my occasionally dominant position which is very unlikely given my trail ride skills I showed today. My 1978 MB100 was, ahh fuk it. There's probably a 150 that could. .

Ok no fuk it I'd still wanker it. I just need to be 20 years younger.

[PVO]

May i ask why your own rods?

Certainly, the main reason is because most snowmobile manufacturers don’t sell the rods individually or the rods they offer are too short. The 850 Etec produced by Rotax, for example, has a rod that would probably work well, however Rotax only sells complete crank assemblies. This is most likely due to the fact the rod is a two piece design that uses a fracturing process to split it. Couple this with the split cage needle bearing and improper assembly and you have a disaster on your hands if it isn't done right.

The other obvious rod options are from Polaris and Arctic Cat. Bore and stroke on these engines are 85mm x 74mm and 85mm x 70mm respectively. My belief is these rods will be too short. I'm still hunting for donor rods but haven't found anything yet and will make one if I have to. I could also concede to having an over square engine but I really don't want to do that.

[PVO]

Very,very interesting that 850 Etec thing
What advantage do You expect going from stock inline to own V2?
Do You have acces to parts for rough measurements or photos?

There are a few big advantages in my application: near perfect primary engine balance, a much narrower package, and an expectation that I can make the V2 lighter than a parallel twin.

I have familiarity and friends with all three major brands. The necessary donor parts will be procured as needed.

[Niels Abildgaard]

There are a few big advantages in my application: near perfect primary engine balance, a much narrower package, and an expectation that I can make the V2 lighter than a parallel twin.

I have familiarity and friends with all three major brands. The necessary donor parts will be procured as needed.

I did a lot of crankshaft speculation for a low mass aircraft engine and a pressed up crank is not low mass.

[URL="https://www.homebuiltairplanes.com/forums/threads/side-valved-two-strokes-for-angels.32119/"]

If You are interested and give me some dimensions I will love to try some alternatives for mass calculation and I know how to balance a V2.

[Condyn]

PVO it seems rods on large bore snowmobile applications are always too short. I think it is because the deck height has constraints to fit in todays tightly packaged chassis.

I have not been following your planning closely, are you wishing to sleeve down the cylinders and increase stroke length to square? I could be wrong, but my gut instinct would tell me In order to achieve a 2:1 r/s ratio with the longer stroke the case volume would rise dramatically, unless you are planning to add to the topside of the cylinder which ends up being a lot of work.
How long are the factory 850 rods?

[TZ350]

.
Next step. Filling the area that the rotary valve is going to go with Knead It polymer repair compound.

Will fill the rest of the case then mill a pocket for the rotary valve back plate.

350776

[wobbly]

Quote " Aluminum should be Ok for the turbine housing as the exhaust gas is much cooler on a two stroke than a four stroke " .
Really TeeZee - I have done two project 2Ts that regularly saw 1280*F , and most all see 1200 all day ?

[F5 Dave]

Interested in what your ignition and power source solution will be Rob.

[husaberg]

Certainly, the main reason is because most snowmobile manufacturers don’t sell the rods individually or the rods they offer are too short. The 850 Etec produced by Rotax, for example, has a rod that would probably work well, however Rotax only sells complete crank assemblies. This is most likely due to the fact the rod is a two piece design that uses a fracturing process to split it. Couple this with the split cage needle bearing and improper assembly and you have a disaster on your hands if it isn't done right.

The other obvious rod options are from Polaris and Arctic Cat. Bore and stroke on these engines are 85mm x 74mm and 85mm x 70mm respectively. My belief is these rods will be too short. I'm still hunting for donor rods but haven't found anything yet and will make one if I have to. I could also concede to having an over square engine but I really don't want to do that.

Hot rods and others sell the bits you need
Making rods as small runs is quite expensive.

http://www.transcanimports.com/downloads/Snowmobile%20Catalogue/Engine%20-%20Connecting%20Rods.pdf
https://www.pro-x.com/prox-connecting-rod-dimensions-brand/
https://www.wandamotor.com/connecting-rods-c-316_2253_2540.html
https://www.kimpex.com/en-ca/products/atv/engine/connecting-rods
http://http://www.samarin.net/?productos (https://www.kevinbreedonracing.co.uk/Products/Conrods/[/URL]
https://www.mitaka.co.uk/MDP.htm
http://catalog.vesrah.co.jp/list/product_parts.asp
http://www.samarin.nl/webshop/index.php?act=viewCat&catId=32
https://www.tkrj.co.jp/product/m-connecting-rod-kit.html
https://www.twsgb.co.uk/hot-rods-con-rods-37-c.asp
[URL="http://www.samarin.net/?productos)
http://www.pvlsverige.se/vrm/index/index22.html

Polaris 700 and 900
C-C 152.1 mm
SE od 27mm
BE od 40mm
SE Width 20mm
BE Width 20mm
SE bearing 22 x 27 x 25 mm

[TZ350]

Quote " Aluminum should be Ok for the turbine housing as the exhaust gas is much cooler on a two stroke than a four stroke " .
Really TeeZee - I have done two project 2Ts that regularly saw 1280*F , and most all see 1200 all day ?

My guess is that 1280*F was seen in the header near the cylinder. I was planning on following these layouts where the Turbo is attached at the stinger. If it is still to hot there I will attach the Turbo to the mid section, where I expect the exhaust gas is at its coolest.

350778350779350780

[TZ350]

Interested in what your ignition and power source solution will be Rob.

At this point I am planning on a DC-CDI Ignitec and total loss 18V 5A/hr electric drill battery. I hate total loss because it so often catches you out with a flat battery but I can't really see what else is possible or practical. Maybe super magnets around the clutch hub. Pole piece with coil fastened outside with the poles reaching through slots in the clutch cover. I think I will start with total loss before this becomes a rainbow bike. You know, the pot of gold at the end of the rainbow. You just never seem to get there.

[husaberg]

At this point I am planning on a DC-CDI Ignitec and total loss 18V 5A/hr electric drill battery. I hate total loss because it so often catches you out with a flat battery but I can't really see what else is possible or practical. Maybe super magnets around the clutch hub. Pole piece with coil fastened outside with the poles reaching through slots in the clutch cover. I think I will start with total loss before this becomes a rainbow bike.

I once seen a mini ignition mag like a KTM 50 rotor mounted on the inside right next to the carb.
it scared me. But your pilot might be braver than me.
350781

I have seen a few with triggers there
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=304753&d=1414574120
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=305408&d=1416113973
or Points
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=305405&d=1416113891

Not sure what Jan did with the Garelli twin Total loss?
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=304414&d=1413876894

THe Exactweld 4 disc tandem Twin no idea how they did the ignition?
https://www.maranello-engineering.com/eshop/images/customers/005/composite.jpg

[Frits Overmars]

Not sure what Jan did with the Garelli twin Total loss?Yep, total loss systems for his Jamathi, Piovaticci, Bultaco, Minarelli and Garelli creations. Most of them carried the battery in the fuel tank.
350783


The Exactweld 4 disc tandem Twin no idea how they did the ignition?Total loss as well.

350782

[Flettner]

Dyno, moved indoors, with the help of Flintstone log rollers.

[JanBros]

as an exhaust pipe does more bad than good at 2/3rd's of rpm of max torque (so before the rpm's the pipe is designed for), is there also such an rpm for the rpm's higher than those the pipe is designed for ?

asking for an idea I have for my moped-MX. standard Honda SKy's are fast to get going from a stand-still/very slow corner's, and I can't seem to keep that good quality while making an engine that's faster once the moped's are moving a bit faster.

So my new idea is : design a pipe that works for a lower rev-range to improve low-speed-acceleration, and since the standard Sky-cylinder has plenty transfer angle area (good enough for over 10.000rpm, rpm's we never reach), and in combination with an 180° exhaust timing, the engine will still (I hope :whistle:) outperform standard Sky's in the highr rev's. Unless the pipe does more wrong than good at a certain rpm above it was designed for. (instead of peaking at 8000, I would want to drop it by about 2.000 to 6.000 rpm)

any idea's ?

[wobbly]

The limiting factors for overev power are three fold - tuned length , rear cone angle , and the length % of the header combined with the angle of the first diffuser cone.

Tuned length basically sets in stone where the peak rpm power will fall.
The rear cone angle is a trade off between peak power ( a steeper cone gives a narrower band of useable power with a high peak number ) , and how fast the power will fall off past its peak.
Finally the shorter ( closer to 30% or less ) and the steeper the initial diffuser angle is , this also enables overev capability - always at the expense of front side power.

In your case simply adding a very shallow ( thus longer ) rear cone will drop the peak power rpm , but then allow the pipe to rev on well past the original designs capability.
There are limitless combinations of course , and never any free lunches to be handed out , but heading out along a reasonably well defined tangent using empirical data is always a good start point.

[TZ350]

.

I am pretty lazy and did not want to dick around with dial gauges to center the rotary table and setup the case on center. So I tapered a length of 1" bright and used the taper to force the job on center.

350789 Centering the Rotary Table with the tapered round bar.

350787 Centering the crankcase half.

350790 Starting to cut the pocket. Depth and inner and outer diameters are critical.

350788 Finished the first half. Depths and diameters worked out perfectly. Now to get the cover sorted.

Suzuki RG50 with a GP125 rotary valve assembly. Maybe it will end up a 50 or I could make a 69cc engine and Turbo Charge it. Such exciting possibilities.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/ZRLK8Gm5DWE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Yep, respirator while working with the Dyno. I understand 2Stroke Stuffings fume problems. I have been using a respirator for a while now as just ordinary fumes from a two stroke can get poisonous after a while. Certainly made me sick.

[Frits Overmars]

as an exhaust pipe does more bad than good at 2/3rd's of rpm of max torque (so before the rpm's the pipe is designed for),
is there also such an rpm for the rpm's higher than those the pipe is designed for?Yes there is Jan, at least in theory. In practice other problems will probably prevent you from reaching that situation.

[lohring]

There are some ways around this problem;they involve changing the length of the pipe. My favorite as a boat racer is water injection into the header. See below. Another is a sliding pipe. I built one where the baffle cone is the moveable part, but sliding headers are more common.

Lohring Miller

350803350802

https://www.youtube.com/watch?v=0odVzSgufjk

[Frits Overmars]

There are some ways around this problem;they involve changing the length of the pipe.... I built one where the baffle cone is the moveable part,
but sliding headers are more common.And more effective.
There are several options in lengthening an exhaust pipe. You can move the end cone, or you can lengthen the header, like a trombone.
The gas pressure generates a force that is proportional to the cross section area of the moving part and proportional to the pressure difference at either side of that area. For a moving end cone this force can be up to 6 times larger than for a sliding header. That is one reason to go for the trombone system rather than the moving cone system.

The second reason: sealing. The circumferential gap that has to be sealed, is three times shorter for the trombone system. That means three times less leakage and three times less friction.

The third reason: say you wish to lengthen the total length of the pipe by 10 %. If you do it by moving the end cone, you will also enlarge the pipe volume by a little over 10 %.
But in a good pipe configuration the header length is about 1/3 of total pipe length, so in the trombone system, lengthening the pipe by 10 % will be done by lengthening the header by about 30 %. That gives a far greater variation in the pipe's Helmholtz frequency than a 10 % volume change.

It is true that the length percentages of all pipe components should be in a rather fixed relation to each other. Varying the lengths of all components by the same percentage would be the theoretical optimum, but that is not feasible.
Lengthening the belly will disturb the optimum relations, as will lengthening the header. So the pipe in its lengthened version will not be the optimum for the low resonance rpm dictated by the length. But it will be a hell of a lot better than using an exhaust power valve that spoils the 180° effective exhaust timing, necessary for true resonance.
And a pipe shortened beyond its optimum may not show the optimum length relations between its components either, but it will be a lot more effective in overrev than artificially raising the exhaust gas temperature by retarding the ignition, or by weakening the mixture strength through closing a power jet, which has the disadvantage that not all inhaled air is used for combustion.

Video courtesy of Rimar Motors:
http://www.youtube.com/watch?v=0odVzSgufjk&feature=youtu.be

[JanBros]

There are some ways around this problem;they involve changing the length of the pipe. My favorite as a boat racer is water injection into the header. See below. Another is a sliding pipe. I built one where the baffle cone is the moveable part, but sliding headers are more common.



I take on a lot of chalenges, but fitting a sliding pipe that survives 4 to 10 hour races on a tiny MX bike (this is for a 50cc moped for MX that cost's about 200 euro race-ready, and that has an engine/transmission combo that is also the swingarm, so the engine moves together with the rear wheel up and down, and the exhaust is entirly curved due to limited space) is a couple of bridges too far ;)


Tnx Frits and Wobbly. I'll built some simple straight pipes and test them on the dyno and see what happens.

[Vannik]

I take on a lot of chalenges, but fitting a sliding pipe that survives 4 to 10 hour races on a tiny MX bike (this is for a 50cc moped for MX that cost's about 200 euro race-ready, and that has an engine/transmission combo that is also the swingarm, so the engine moves together with the rear wheel up and down, and the exhaust is entirly curved due to limited space) is a couple of bridges too far ;)


Tnx Frits and Wobbly. I'll built some simple straight pipes and test them on the dyno and see what happens.

Have you thought of playing with a pipe that has a perforated rear cone as used by karts? It has two tuned lengths which might help, but it is at the expense of peak power?

[husaberg]

Have you thought of playing with a pipe that has a perforated rear cone as used by karts? It has two tuned lengths which might help, but it is at the expense of peak power?

That raises an interesting point or two, multiple outlets controlled by solenoids (pun almost intended)

or variable iris outlets at different points in the stinger, so they rely on different venturis along the stinger to control the length. or even different pipes
https://cdn.dribbble.com/users/839341/screenshots/3279699/iris.gif
https://www.tlv.com/global/images/steam_theory/types-of-valves/0704daiyafuramu.gif
https://3.bp.blogspot.com/-3yz6ssMwepE/VyMpkpEebGI/AAAAAAAABIk/bhRnflpJcsg_SdNmW6oLConPSH7hO6_vwCLcB/s1600/11schuifan.gif

it fails on Kiss and likely reality but putting it out there.

but yes the gp rider should be sacked for being out of the powerband, but lesser mortals on Dirtbikes. Are generally less talented and are self employed

[JanBros]

Have you thought of playing with a pipe that has a perforated rear cone as used by karts? It has two tuned lengths which might help, but it is at the expense of peak power?

no, any design rules ?
* same rear cone but perforated ? in a cylindrical chamber ?
* or steeper perforated cone inside a shallower cone ?
* relationship between perforated and non-perforated surface ? 50-50 ? or is it simply a of less perforated = more emphasis on power at high rev's and visa versa ?

[Vannik]

no, any design rules ?
* same rear cone but perforated ? in a cylindrical chamber ?
* or steeper perforated cone inside a shallower cone ?
* relationship between perforated and non-perforated surface ? 50-50 ? or is it simply a of less perforated = more emphasis on power at high rev's and visa versa ?

I do not know. I only recently understood its workings, thanks to a very kind member that supplied me with pressure traces. The hole size, number and positions are prescribed for the karts in a homologated pipe. So you will have to experiment.

The number/size/position of the holes determine the ratio between the two tuned length pulses.

[lohring]

A 50 cc engine is huge by my standards. Below is a sliding pipe on a 7.5 cc model boat. It was connected to the rudder travel so he pipe was lengthened in the turn when increased drag pulled the rpm down. The silicone tube seals the pipe to the movable section. The sliding joint is sealed by a water cooled o-ring.

Water injection in the turns was so effective that one district outlawed it. We used water injection to be able to launch and accelerate with with larger props to set straight line records. We used a simple, servo actuated on/off valve.

Lohring Miller

350804350805350806350807

[lohring]

"And more effective. "

The pipe with the movable baffle cone also could be moved along the header. We found that the diffuser position had a much smaller effect than changing the tuned length. There was a definite sweet spot that turned out to be close to the designed lengths of the pipe sections. If I had had the wisdom of the people on this forum at the time I wouldn't have spent the time building such a complex pipe. However, It turned out to be really effective on stock engines with low exhaust timing and a restricted intake tract. The high horn coefficient and large volume wasn't needed for modified engines.

Lohring Miller

[TZ350]

.
350808

Outer rotary valve cover and ignition trigger.

[PVO]

I did a lot of crankshaft speculation for a low mass aircraft engine and a pressed up crank is not low mass.

[URL="https://www.homebuiltairplanes.com/forums/threads/side-valved-two-strokes-for-angels.32119/"]

If You are interested and give me some dimensions I will love to try some alternatives for mass calculation and I know how to balance a V2.

Thanks for your offer, I will keep it in mind as the design progresses. I'm not far enough along to provide any solid design parameters.

The big issue in my opinion for a single piece crankshaft for this type of two stroke is the split cage big end bearings and need to assemble the conrod perfectly to ensure the bearings last. The fracture method is preferred by Rotax but those rods aren't sold without being assembled to the crank and it is unlikely I'll be able to replicate their process.

[PVO]

PVO it seems rods on large bore snowmobile applications are always too short. I think it is because the deck height has constraints to fit in todays tightly packaged chassis.

I have not been following your planning closely, are you wishing to sleeve down the cylinders and increase stroke length to square? I could be wrong, but my gut instinct would tell me In order to achieve a 2:1 r/s ratio with the longer stroke the case volume would rise dramatically, unless you are planning to add to the topside of the cylinder which ends up being a lot of work.
How long are the factory 850 rods?

I agree, the rod length manufacturers are selecting has a lot to do with packaging. For me, since I'm designing the package I think I'd prefer to get good rod length, case volume, and reduce thrust loading first and then work the packaging second. I like to design in parallel so I can iterate on both as needed.

Arctic Cat is the only manufacturer with an engine design that has the cylinders made individually in the 800-850cc class. Everyone else uses a mono block cylinder so they won't work.

My plan is to design and cast the cylinders for my engine. They are the heart of a two stroke so compromising on the cylinder is a false step to take early on in my opinion. I've designed two stroke cylinders for others based on the design principles shared by Frits, Jan, Wobbly, Vannik, and others and have achieved good results so I don't feel like this is an overwhelming task and I quite look forward to it.

I don't know the 850 rod length but wish I did to establish a starting point. As I've mentioned to others you cannot purchase 850 rods without buying the crank assembly.

[PVO]

Hot rods and others sell the bits you need
Making rods as small runs is quite expensive.

http://www.transcanimports.com/downloads/Snowmobile%20Catalogue/Engine%20-%20Connecting%20Rods.pdf
https://www.pro-x.com/prox-connecting-rod-dimensions-brand/
https://www.wandamotor.com/connecting-rods-c-316_2253_2540.html
https://www.kimpex.com/en-ca/products/atv/engine/connecting-rods
http://http://www.samarin.net/?productos (https://www.kevinbreedonracing.co.uk/Products/Conrods/[/URL]
https://www.mitaka.co.uk/MDP.htm
http://catalog.vesrah.co.jp/list/product_parts.asp
http://www.samarin.nl/webshop/index.php?act=viewCat&catId=32
https://www.tkrj.co.jp/product/m-connecting-rod-kit.html
https://www.twsgb.co.uk/hot-rods-con-rods-37-c.asp
[URL="http://www.samarin.net/?productos)
http://www.pvlsverige.se/vrm/index/index22.html

Polaris 700 and 900
C-C 152.1 mm
SE od 27mm
BE od 40mm
SE Width 20mm
BE Width 20mm
SE bearing 22 x 27 x 25 mm

Thank you for these references - more stuff to look through and consider!

[TZ350]

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2Stroke Stuffing is getting somewhere. He is now nipping at the heals of the best conventional Dutch racing 50cc engines.

[Muhr]

My guess is that 1280*F was seen in the header near the cylinder. I was planning on following these layouts where the Turbo is attached at the stinger. If it is still to hot there I will attach the Turbo to the mid section, where I expect the exhaust gas is at its coolest.


Glad to see you embark on such a project! Will be interesting to follow.
You gave me motivation to continue my project that has been going on for ages.

[Flettner]

Wobbly, who was the company you deal with to get your dyno load cells and associated softwear?

[ken seeber]

Wobbly, who was the company you deal with to get your dyno load cells and associated softwear?

"Dominik
All Aliexpress. From memory the cells were about $30 and the displays maybe $50 I think. Brett can confirm
Today at 4:19 PM
4:19 PM

Brett
Yep'

[Muhr]

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2Stroke Stuffing is getting somewhere. He is now nipping at the heals of the best conventional Dutch racing 50cc engines.

Does not want to be negative but looked like he was doing a negative RPM pull? which should mean that the power reading is a combination of engine power and and braking power?(If he brakes harder he can have 100hp)

[SwePatrick]

Does not want to be negative but looked like he was doing a negative RPM pull? which should mean that the power reading is a combination of engine power and and braking power?(If he brakes harder he can have 100hp)

The software is smarter than that :)
It measures the amount of power it takes to pull down the engine at a certain rpm per second.
And if breaking it harder it knows the power because the rpm goes down faster.

Totally normal.

[Muhr]

The software is smarter than that :)
It measures the amount of power it takes to pull down the engine at a certain rpm per second.
And if breaking it harder it knows the power because the rpm goes down faster.

Totally normal.

Ok so he has a load cell also on the magnetic brake to equalize the braking force the rotating mass?
Thought the bench was much simpler composition.

[wobbly]

Flett - I have used SportDevices software and their SP1 dyno data pack for over 15 years - the basic data box can do inertia or load cell or both.
After testing everything from Superflow to DynoMite etc , this is by far the easyest to use.
And it has two K type temp inputs on the front I use for egt and water temp.
All the inputs are configurable for stuff like Lambda , fan control etc.
The software is super easy to use , and I have the option of a Hall Effect sensor that reads the 126 teeth on the starter flywheel ( a small Toyota auto flex plate ) that is geared 1:1 to the flywheel.
I have asked them for many upgrades to the software ( free download ) and they do them very quickly.

The latest software versions specifically for Windoze 10 you have to be careful to download a driver to suit the old ( very ) serial port - RS232 that the box uses.
This really is the correct data system for reliable transfer in any noisy industrial applications , but of course nowdays no laptops or desktops have serial anymore
so you need to use an adapter.
Sportsdevices can give you a cable ( oddball ) that has the Serial to USB adapter on the computer end ie the cable is actually Serial wires , this works perfectly.
But maybe the latest version has usb as a default , dunno.

The only thing I would insist on , that many ignore , is to get a one way clutch , as is sold for tractor pto drives for mowers etc.
Then if an engine locks up , the dyno inertia wont keep driving the crank around to complete its destruction.

[Flettner]

Thankyou Wobbly, Ken, Brett

[porttiming124]

Good morning all . I am currently working on an engine that has two rings and I am looking for a piston with only 1 ring that I cannot find. If I remove the bottom ring is that the groove will serve as a bypass between the transfer and the exaust. I think the groove is so small that maybe it doesn't show. what do you think about it? thank you.

[Frits Overmars]

I am currently working on an engine that has two rings and I am looking for a piston with only 1 ring that I cannot find. If I remove the bottom ring is that the groove will serve as a bypass between the transfer and the exhaust. I think the groove is so small that maybe it doesn't show. what do you think about it? thank you.The groove will indeed constitute a bypass. Whether it will actually serve as a bypass, depends on the exhaust and transfer pressures.
As you say, the effect may be small. Just try it; you've got nothing to lose.

[ken seeber]

Good morning all . I am currently working on an engine that has two rings and I am looking for a piston with only 1 ring that I cannot find. If I remove the bottom ring is that the groove will serve as a bypass between the transfer and the exaust. I think the groove is so small that maybe it doesn't show. what do you think about it? thank you.

Over herein Oz around a century ago, there was an engine used in karting for little kids, it was called the Comer S80 or SW80.
It had a chrome bore and a 2 ring piston. The tuning trick of the day was to reduce friction from the second ring. The rules stated that both rings must be in place.
What the "gun" tuners did was to reshape the second ring such that it was tensioned into the ring groove, ie making no contact with the bore, but still there to prevent short circuiting and also satisfy the rules.
To achieve this, the ring was squeezed into an "undersize" ring, such that the ends must have overlapped, ie forming a helix. Then it was heated, presumably to some annealing temperature, maybe 800 - 900 C for cast iron, less for steel.

Then it was fitted to the groove such that it was tight to the bottom of the ring groove. Clever ??

So, if you have old rings to play with, maybe this is the go.

No guarantees though.

[lohring]

"The only thing I would insist on , that many ignore , is to get a one way clutch , as is sold for tractor pto drives for mowers etc.
Then if an engine locks up , the dyno inertia wont keep driving the crank around to complete its destruction. "

Amen to that. I've never seen an engine as completely destroyed as when we seized one at over 10,000 rpm on the way to a 20,000 rpm pull. We had a centrifugal clutch and a square coupler that linked the engine to the wheel, but not a one way clutch. The coupler was twisted 180 degrees before the clutch let go. Fortunately it was a 26 cc engine. A bigger engine would be a lot more expensive.

Lohring Miller

[TZ350]

.

350821

2Stroke Stuffing. Was that really 30hp????? https://youtu.be/MIDaSh3o380https://youtu.be/MIDaSh3o380 I am not sure about the durability of the results but I am very impressed by his energy, honesty and resourcefulness in developing that supercharged 50cc engine.

[KKT]

This may well be really dumb questions.. :)

Looking from the bottom of a cylinder for a two stroke: Is there a relation between the area of the transferducts and the area of the cylinderbore, and the volume of all transfers vs the cylinder volume ?
How do you know if the transferducts are large enough for a given cylinder capacity ?

[ken seeber]

Been thinking about 2 Stroke Stuffing. If we had an in-cylinder pressure trace it would be interesting if there was significant pressure decay prior to exh port opening, as is pretty much normal. Now, to get more power, it’d just so useful to have a higher pressure in the cylinder before EPO.

He has the ability to pump in more charge because he has a blower. This is on the basis that it can provide a greater gas flow than the blower than can be achieved with regular crankcase/exh tuning flow.

Going back to current tuning stuff, the usual thing is to go for a high CR (ie small head volume) to maximise the efficient burn of the available charge, consistent with detonation control etc.

Now if Alex can provide more mass flow thru the cylinder, he is ultimately limited to a total trapped volume of the cylinder trapped volume after EPC plus the head volume.

So, what if he increased the head volume? This would mean more charge mass in the cylinder at EPC and therefore more mass of charge to burn and reduce the pressure decay prior to EPO. This would/could mean more power.

Free lunch ???

[Frits Overmars]

Free lunch ? Pretty much. But first:
He has the ability to pump in more charge because he has a blower. Right, but more importantly, he has the ability to keep in more charge because he has a rotary exhaust disc that closes the exhaust before the transfers, so he can really supercharge the cylinder.
Next: an increased combustion chamber volume makes it possible to pump more mixture in because the pressure rise will be less steep (that is also true for a conventional two-stroke with an expansion pipe).
A lower compression ratio equals a lower expansion ratio which again would be great if he were to use an expansion pipe because the pipe would then be fed with high-energy exhaust gas. But even without such a pipe a low expansion ratio is good for power because it means a smaller pressure drop between maximum pressure and pressure at exhaust port opening, in other words, a higher mean pressure during the expansion stroke (this is how you make 1000hp-per-liter dragsters survive: a verging-on-tolerable peak pressure that hardly drops off).
For Alex however, lunch will not be completely free because in his case the exhaust gas energy is wasted. And with fuel prices these days....
350824350823 350822

[wobbly]

I was recently amazed to learn of a Volvo stern drive boat engine that is supercharged as well as turbocharged.
On part throttle the supercharger is designed to increase mid range power and economy , then when giving it a handful the turbo spools up and uses the " free " exhaust energy
to dramatically increase top end power.
I sure don't want Alex going off on another weird arse tangent , but Frits mentioned the only partial free lunch due to loss of exhaust energy.

[pete376403]

Some big GM diesel two strokes are both turbo and supercharged.

[ken seeber]

I was recently amazed to learn of a Volvo stern drive boat engine that is supercharged as well as turbocharged.
On part throttle the supercharger is designed to increase mid range power and economy , then when giving it a handful the turbo spools up and uses the " free " exhaust energy
to dramatically increase top end power.
I sure don't want Alex going off on another weird arse tangent , but Frits mentioned the only partial free lunch due to loss of exhaust energy.

"The lunch will not be completely free "

I guess that means just another half sandwich (ham, cheese and tomato) then...:weep:

[husaberg]

I was recently amazed to learn of a Volvo stern drive boat engine that is supercharged as well as turbocharged.
On part throttle the supercharger is designed to increase mid range power and economy , then when giving it a handful the turbo spools up and uses the " free " exhaust energy
to dramatically increase top end power.
I sure don't want Alex going off on another weird arse tangent , but Frits mentioned the only partial free lunch due to loss of exhaust energy.

In the 4t world the Nissan march engine that was about 900cc was a super turbo as were a few fire engines in the states
The later Detroits were supercharged scavenges with an additional turbo, which i suspect was also for noise reduction as well.

Surely as its hot a tubo might help burn off unburnt fuel and possibly emissions in a 2t
http://cdn.shopify.com/s/files/1/0196/3764/articles/ST9_1200x1200.jpg?v=1588212507
https://en.wikipedia.org/wiki/Nissan_MA09ERT_engine

https://gomotors.net/photos/f5/83/image-attached_91d09.jpg?i
http://2.bp.blogspot.com/-FEG8qfNY9qA/UH0bj_i--II/AAAAAAAABqo/hibIdWBesus/s1600/MA09ERT.jpg

[vro46i]

Stepped pins can be made to be reliable , but its so much easyer to use a CNC spark errosion process.
A good operator will know what copper electrode size to use and can adjust the current to get a dead straight sized hole on exactly the correct stroke.
Ive done this several tines now , with only one hole being a little tight.

Edit - its really good for destroking , as you make the new hole on center , but oversize , and use a spacer sleeve to re establish the press fit.
That way the actual new hole size is immaterial , as long as they are all the same.
Depending upon the flywheel OD lengthening the stroke this way could make the web too thin above the pin hole.

Hi Wobbly, I have arrived at the stage of destroking the engine from 125cc to 110. Using an oversized big end pin (24mm dia) where previously a 22mm dia. The machinist is going to offset bore it to fit the new big end pin to achieve the required stroke. Can you please tell me, how much of an interference fit does the big end pin to the new crank web hole is acceptable? 2 -3 thou? Thanks in advance.

[Vannik]

I was recently amazed to learn of a Volvo stern drive boat engine that is supercharged as well as turbocharged.


https://deltahawk.com/

One of the lead designers is on this forum :drool:

[husaberg]

https://www.youtube.com/watch?v=3GT8Ueaug7A

[136kg136ps]

I worked on 2 stroke 16V149 Detroits Diesels that had 4 turbos, two bypass superchargers, intercooling, ceramic coated piston tops and chambers to produce just under 1 hp per cubic inch in the 1980s. The piston skirt and top were seperate and they used 4 exhaust valves per cylinder.

Used for industrial and military generators and marine propulsion. They were something to behold. Leaky, noisy and prone to fires caused by oil spray from turbo oil lines soaking lagging and catching fire. I had to rescue a coworker once using a firefighting oxygen unit when he was overcome by fumes from a fire.

The bypass kicking off could be heard through supposedly soundproof enclosures and felt as a pressure change.

I got to thinking about the role crankcase pressures played a part in two stroke operation with them because when all cylinder block leaks were sealed, a catastrophic failure was likely imminent.