ESE's works engine tuner

[guyhockley]

:cool:Similar design
...only two stroke in it
More appropriate for this thread

When I lived in Belgium (up to 4 years ago) there was a house nearby that had a collection of 2 stroke cars and vans parked around it, mostly pretty sorry looking examples, sadly.
If you search "Grensstraat 10, 3078 Kortenberg, Belgium" on Google Street View you can see that some of them at least were still there when the Google camera car went past.

[lucf]

After a long time a small update.
First of all, see the new factory that is also a big improvement.
The engines have been reliable and ready for sale for several months.
At the moment enough people who are still very enthusiastic and have also bought an engine, and I'm sure they would not have been if the power was only 35hp.
Their enthusiasm was most intensified after making a test drive, which can take place almost every day by appointment.
The sold engines will certainly participate in competitions this year.

I can't edit my previous post so again with an better link

https://www.facebook.com/photo.php?fbid=10210600872177086&set=a.10210600871137060&type=3&theater

[Haufen]

After a long time a small update

Please don't, you're wasting your breath.

[TZ350]

When I lived in Belgium (up to 4 years ago) there was a house nearby that had a collection of 2 stroke cars and vans parked around it, mostly pretty sorry looking examples, sadly. If you search "Grensstraat 10, 3078 Kortenberg, Belgium" on Google Street View you can see that some of them at least were still there when the Google camera car went past.

I had a look, I guess they are still there but are obscured in the pictures.

[TZ350]

340277 340276

I went to an experimental electric vehicle get together tonight where people talked about their latest projects and all things EV that they were up to.

And by chance I saw this portable go kart dyno that they make here. A very clever piece of kit. Not only the normal dyno functions like rolling road simulation and direct axle coupling it could mimic a track and put the cart through the same demands as if it was racing by simulating the track. Not only can you use this dyno for tuning at the track on race day. By using the computer control system to simulate a circuit you can use the dyno anytime to tune pipe ignition etc for the best lap time and base setup for any particular track.

[jbiplane]

I saw this portable go kart dyno that they make here. A very clever piece of kit.

Is it possible find portable design for 5...50hp to use just for 7000-18000rpm engines?

BTW I am making my variant of kteuzkopf engine. Very differs of Rugers.

[TZ350]

340280340281


Is it possible find portable design for 5...50hp to use just for 7000-18000rpm engines?

This should be the contact email:- tonybankart@gmail.com


BTW I am making my variant of kteuzkopf engine. Very differs of Rugers.

340282

Very interesting motor. I love the position of the fuel injector, I wish I could get mine so directly under the piston so it can squirt onto the under side of the piston crown to cool it.

[Muhr]

Certainly old news here, but think it was entertaining reading about a mechanical push rod injection

first I thought it was united flow design but it just seems to be exhaust

http://capellossiiv.blogspot.com/2015/07/honda-files-patents-for-brand-new-fuel.html?m=1

[guyhockley]

I had a look, I guess they are still there but are obscured in the pictures.
Interesting. Searching from the UK, I could see 3 parked on the street with obscured plates (Trabant, Wartburg and, I think, Barkas van) but the garden was fuzzed out. Assumed it was just my crappy phone...

[katinas]

BTW I am making my variant of kteuzkopf engine. Very differs of Rugers.

Are you tried it, or still in process. On Experimental Aircraft Association forum I saw one, maybe, earlier version (posted photo some time ago )

Last year I prepared for the tests two different pistons, different from previous tested versions, but at the end one looks too fragile, another too heavy, so nothing was tested. Like always, never know what happens tomorrow. Best luck for your projects.

Another two inventions with separated crankcase. Christian Vialette called it Three-stroke.

https://patents.google.com/patent/EP0020806A1/en

https://patents.google.com/patent/EP0337768A2/en

[katinas]

Interesting. Searching from the UK, I could see 3 parked on the street with obscured plates (Trabant, Wartburg and, I think, Barkas van) but the garden was fuzzed out. Assumed it was just my crappy phone...

Another RED twooooo stroke. Barkas.

https://wp.ifaclub.co.uk/the-vehicles/

And crank from Syrena 104 105 car
And 1938 Steinhagen i Stransky engines from Poland, but didnt found the car

[katinas]

Another RED twooooo stroke. Barkas.

https://wp.ifaclub.co.uk/the-vehicles/

http://www.mcnews.com.au/1966-mz-re250-two-stroke-racer/

https://classic-motorbikes.net/bimota-ringhini-350-twin/

http://www.buecker-fliegen.de/motorrad/index.php?option=com_phocagallery&view=category&id=8&Itemid=13

[lohring]

Is it possible find portable design for 5...50hp to use just for 7000-18000rpm engines?

BTW I am making my variant of kteuzkopf engine. Very differs of Rugers.

Below is the picture of our inertial dyno. We've tested 23 to 35 cc engines with 2 to 12 hp at up to 25,000 rpm. It's on a mobile cart.

Lohring Miller

340299

[Frits Overmars]

Is it possible find portable design for 5...50hp to use just for 7000-18000rpm engines?Here is our mobile dyno for 6,5 cc F3D engines. About 5hp; maximum rpm is about 36.000. Note the quick-change pipe mounting :rolleyes:.
340304 340303 340305 340306

[Michael Moore]

A bit OT, but who (besides Nova) is making 2T race transmissions? Do the shifter kart engine manufacturers do them in house or are there a few "standard" sources that provide them to the OEMs?

It used to be that if you wanted a race transmission you could start with an RD/RZ and drop TZ parts in, or go to your local dealer and buy RS125/TZ125 parts, or maybe pick up something from a 125/250 Rotax race engine. But all those engines have been out of production for 10-25 years now.

I've heard that the NSF250R is basically using the late RS125 box, but I don't know how available bits from something like that would be, especially here in the US where GP racing is pretty much dead.

At one time in Italy you could become a m/c manufacturer by shopping at Minarelli/Franco Morini for engine, Dell'Orto for carb, Verlicchi for a frame, Grimeca for wheels, Marzocchi or several others for suspension, CEV/Aprilia for electrics etc etc and then just assemble the parts. Do the modern 2T race engine makers have a race transmission company they shop at who can supply "off the shelf" turn key primary drives/transmissions?

Many of the modern 4T transmissions have plain bearings and need a pressure oil feed to them (but not Ducati, as used in the Tularis 2T twin special) so they are not suitable for easy grafting in to a DIY project unless an oil pump is added. A transmission/clutch sized for the torque spikes of an 1100 Duc twin seems like it might be overkill (though strong) for a 125-250 2T engine. But the Ducati looks like it is about the main option for a readily available and affordable gearbox clutch for an engine project. I suspect there are other options but I'm looking in the wrong places for them.

cheers,
Michael

[Grumph]

Might not be the layout you want Michael - but have a look at TT Industries website. 5 and 6 speed boxes with magnesium cases even...
Sized for good HP and quite light.
Bruce Verdon's a good guy - and open to doing specials if the price is right. More interested if he sees a market.

And not far up the coast from Husa...

BTW, I've yet to see a late 4T gearbox with plain bearings. Got an example ?

[koenich]

TZ250 gear box parts seem still available at Yamaha (www.yamaha-original-teile.de at least has a lot). How about 250 MX stuff? KTM gear boxes are great stuff...

[Larry Wiechman]

Now for something completely different. https://www.youtube.com/watch?v=JxLb3Yqqds4 https://www.youtube.com/watch?v=brT-BafQ-eg

[Michael Moore]

I've got a 2015 KTM 250SX engine and the 5 speed has a larger, instead of smaller, % drop from 4->5. I can put an entire 6 speed from an XC (not the XC-W) in and it would be an improvement but the 3rd through 6th % drops are kind of wide, all of them more than the typical Ducati (and 5->6 looks to be about 25-30% wider than would be appropriate for higher speed track use).

A complete new XC box is about US$900 for the gears/shafts/clips/shims plus the drum/forks add another $100-200. I looked at the 2013 250 SX-F fiche and that 6 speed seems possible on the ratios but it has a few bushings and I don't know if it is a drop in. The 2T 250/350 share transmissions with the 350 4T but I can't find any significant interchange with the 250-F, and later Fs are 5 speed.

FWIW, the 250SX 5 speed drops are 20, 16.7, 14.3 and 16.5% from bottom to top.
A 350 Bultaco/AJR is 25, 17, 15 and 8.
The XC has 24.4, 20, 16.4, 15.8 and 12.6% so 6th could be closer to 5th.
The "small" Duc standard street 6 speed (not the high first gear Corse) is 32.3, 20, 15.2, 11.5 and 7.7. The Duc Corse is pretty much the same but with a 28% drop when shifting to 2nd.
I have a 2003 TZ250 as 25.6, 16.1, 11.9, 8.3 and 7.4%

Those Ducati ratios look pretty good to me and are used in a good 10+ years of recent models and are plentiful on eBay. But that means making new crank cases, which could be a fun project and also let me see about adding a balance shaft, but it pushes a running bike even farther into the already hazy future.


Yes, it may well be that for the few times it gets run as a track day bike (if I get it built) the 5 speed with a fairly standard MX tune (I bought a Pro Circuit chamber that is supposed to maintain the 50 hp peak for another 1000-1500 RPM) will be fine for my mediocre riding skills, and the XC would be better. But even though I'm transitioning to "former racer" I still like to have things the way I think they ought to be. I wish I'd known more about KTM when I bought this engine, and was clairvoyant so I could see that they'd be adding an effective balance shaft in the major engine redesign for 2017. Neil's transfer port injection which is on some new KTMs would be nice to have too. :)

Greg, I was surprised when I looked at late Yam/Kawa/Suzuki 600 part fiches as they were my first though on possible donors. Not only are the idlers generally running on a bush (separate from the gear) but some of those bushes have internal splines to keep them from spinning on the shafts, which I'd never seen before. I looked at some photos of the parts on eBay to verify it wasn't just needle bearing details being left off the drawing. In some you can see the internal oil grooves and drillings to let oil get out to the bush/gear interface.

The TT Industries parts do have a good reputation, but isn't everything they do for pre-unit British stuff?

An XC 6 speed with tighter custom 5th and 6th gears would most likely be fine, if it was possible to get those gears designed and made at an affordable price. But for the price of those gears (and probably for less) I can get a complete Duc lower end and have clutch and primary gears too, as well as no special replacement parts.

A pal sent some primary gear parts to Ellis Moore at Moore Engineering in England to get some parts made but he told me that Ellis had a race crash last year that left him paralyzed from the chest down and he's closed his shop and his parts are coming back. Ellis was keen on one-off stuff (which Nova is not) and appears to have supplied high-quality parts at reasonable prices so his accident is a loss to the industry (as well as being tragic, I know other racers who've ended up in wheelchairs).

A friend who purchased a TZ125 last year has been telling me of some major parts that aren't to be found as NOS, and now that I'm done with vintage bikes I'd like my remaining projects to not involve massive part searches. It is difficult enough to finish things without getting hung up on "wish I could find a new one of these" issues.

So when I saw various cool 125-250 shifter kart motors of modern manufacture it had me wondering what they are doing for gearboxes, and this seemed like the place mostly likely to have someone who knows.

cheers,
Michael

[husaberg]

A bit OT, but who (besides Nova) is making 2T race transmissions? Do the shifter kart engine manufacturers do them in house or are there a few "standard" sources that provide them to the OEMs?

It used to be that if you wanted a race transmission you could start with an RD/RZ and drop TZ parts in, or go to your local dealer and buy RS125/TZ125 parts, or maybe pick up something from a 125/250 Rotax race engine. But all those engines have been out of production for 10-25 years now.

I've heard that the NSF250R is basically using the late RS125 box, but I don't know how available bits from something like that would be, especially here in the US where GP racing is pretty much dead.

At one time in Italy you could become a m/c manufacturer by shopping at Minarelli/Franco Morini for engine, Dell'Orto for carb, Verlicchi for a frame, Grimeca for wheels, Marzocchi or several others for suspension, CEV/Aprilia for electrics etc etc and then just assemble the parts. Do the modern 2T race engine makers have a race transmission company they shop at who can supply "off the shelf" turn key primary drives/transmissions?

Many of the modern 4T transmissions have plain bearings and need a pressure oil feed to them (but not Ducati, as used in the Tularis 2T twin special) so they are not suitable for easy grafting in to a DIY project unless an oil pump is added. A transmission/clutch sized for the torque spikes of an 1100 Duc twin seems like it might be overkill (though strong) for a 125-250 2T engine. But the Ducati looks like it is about the main option for a readily available and affordable gearbox clutch for an engine project. I suspect there are other options but I'm looking in the wrong places for them.

cheers,
Michael

NSR250 has a cassette box and gear oiler. You can fit the alternative ratios from a early RS250
Pretty sure the shifter karts manufacturers make their own
the CR honda based shifter karts use a later engine with a early gearbox
The earlier Husaberg had very compact gearboxs based on Husky's. 4/5/6 options wide and close
one of the stonger gearboxs i have seen with decent ratios is the humble VT250 honda they used the same basic gearbox on the MVX250 triple and the CBR250.
they have a planetary gear mechanism and thin big dia gears hence they are very narrow clusters
340333
i also think BRT make their own gearboxs for their new engines
one gearbox that does have pretty reasonable gear ratios is the GT380 they only changed two ratios for the Barton and one of them is able to be subsituted by using a GT250A second gear
the similar gearset was used over a wide range of Suzukis

[Michael Moore]

Thanks for that information. I should have included that I'm looking for modern stuff. I've sold all my vintage bikes and bits and I don't intend to have them again. Been there, did that, and wasted too many years with "I wonder where I can find one of these?" issues so while it doesn't have to be 2019, parts need to still be readily available off the shelf at a US warehouse.

The Banshee has been out of production for about 10 years now I think (and has ATV-style ratios) so even that is getting a bit on the old side (to match me).

If the kart folks are doing everything in house that sounds like fairly low production quantities with subsequent higher prices, so Ducati is looking like a distinct possibility.

cheers,
Michael

[husaberg]

Thanks for that information. I should have included that I'm looking for modern stuff. I've sold all my vintage bikes and bits and I don't intend to have them again. Been there, did that, and wasted too many years with "I wonder where I can find one of these?" issues so while it doesn't have to be 2019, parts need to still be readily available off the shelf at a US warehouse.

The Banshee has been out of production for about 10 years now I think (and has ATV-style ratios) so even that is getting a bit on the old side (to match me).

If the kart folks are doing everything in house that sounds like fairly low production quantities with subsequent higher prices, so Ducati is looking like a distinct possibility.

cheers,
Michael

Pretty sure the Vt's probably still in production in one form or another somewhere a gearbox doesnt care how old it is only how it works.

[jamathi]

A bit OT, but who (besides Nova) is making 2T race transmissions? Do the shifter kart engine manufacturers do them in house or are there a few "standard" sources that provide them to the OEMs?

It used to be that if you wanted a race transmission you could start with an RD/RZ and drop TZ parts in, or go to your local dealer and buy RS125/TZ125 parts, or maybe pick up something from a 125/250 Rotax race engine. But all those engines have been out of production for 10-25 years now.

I've heard that the NSF250R is basically using the late RS125 box, but I don't know how available bits from something like that would be, especially here in the US where GP racing is pretty much dead.

At one time in Italy you could become a m/c manufacturer by shopping at Minarelli/Franco Morini for engine, Dell'Orto for carb, Verlicchi for a frame, Grimeca for wheels, Marzocchi or several others for suspension, CEV/Aprilia for electrics etc etc and then just assemble the parts. Do the modern 2T race engine makers have a race transmission company they shop at who can supply "off the shelf" turn key primary drives/transmissions?

Many of the modern 4T transmissions have plain bearings and need a pressure oil feed to them (but not Ducati, as used in the Tularis 2T twin special) so they are not suitable for easy grafting in to a DIY project unless an oil pump is added. A transmission/clutch sized for the torque spikes of an 1100 Duc twin seems like it might be overkill (though strong) for a 125-250 2T engine. But the Ducati looks like it is about the main option for a readily available and affordable gearbox clutch for an engine project. I suspect there are other options but I'm looking in the wrong places for them.

cheers,
Michael

Most gears in Italy were made by CIMA at Bologna

[Michael Moore]

Thanks Jan

http://www.cimaingranaggi.it/en

[jbiplane]

Are you tried it, or still in process. On Experimental Aircraft Association forum I saw one, maybe, earlier version (posted photo some time ago )

The customer hecitate few months, now it is the last iteration. CNC machining would start next week. Thanks for interesting patents!


Here is our mobile dyno for 6,5 cc F3D engines. About 5hp; maximum rpm is about 36.000. Note the quick-change pipe mounting :rolleyes:.
Thanks Fritz!


Below is the picture of our inertial dyno. We've tested 23 to 35 cc engines with 2 to 12 hp at up to 25,000 rpm. It's on a mobile cart.
340299
Thanks Lohring!

[Vannik]

Thanks Jan

http://www.cimaingranaggi.it/en

Michael,

Why do you not just make a closer ratio 5th gear? That is what we used to do years ago on another project.

[peewee]

i would use the latest ktm sx trans. if 5th gear doesnt suit then make a new one. 125 version would be even better since theres 6gears

[guyhockley]

Michael, if you search for kart homologation pdf some of them will give you information like gear teeth numbers, centre distances etc, but it's a bit of a lottery. Maybe include engine or motor and, probably, kz to avoid all the carb and chassis stuff. I have a load but I'm away from my computer for a few days.
Check out VM Motors, their production part prices seem way better than the Italian ones (they are Czech).
They also were at a Motorsport trade show a while back saying they would do custom work.

[guyhockley]

https://www.vmmotor.com/www/vmmotor/fs/catalogue-vm125-m02-beng.pdf

[Michael Moore]

Gear making is one of those many subjects where I've read a bit about it but I've never attempted it (other than one small oil pump drive gear in machineable wax CNCd as a test to see how it would come out). If the shaft center distances don't match what my software says is appropriate for a standard gear then I'm at sea on how to proceed on modifying gear profiles. It appears there are a lot of non-standard gears in use in motorcycles. I've already got experience with subjects where I've uttered the phrase "how hard could it be?" and I suspect gear making could easily supply the same answer as the other subjects: "wow, that was pretty hard."

:)

I'm going to pick up a Ducati lower end (offered at a very low price as the person has a literal heap of them) tomorrow for inspection.

I've also got a new 2017 250 crank and a set of lightly used matching counterbalancer and dual pinion primary gear coming and I'll be interested to see how the balance factor is done.

thanks,
Michael

[jato]

Years ago i measured a 95 RS125 crank for its balance factor and from memory it was 47% - i was expecting 50% but i used the top half of the rod as reciprocating although people often use just the top third. I didn't have the balance shaft to measure but surely it would equal the crank.

[husaberg]

Gear making is one of those many subjects where I've read a bit about it but I've never attempted it (other than one small oil pump drive gear in machineable wax CNCd as a test to see how it would come out). If the shaft center distances don't match what my software says is appropriate for a standard gear then I'm at sea on how to proceed on modifying gear profiles. It appears there are a lot of non-standard gears in use in motorcycles. I've already got experience with subjects where I've uttered the phrase "how hard could it be?" and I suspect gear making could easily supply the same answer as the other subjects: "wow, that was pretty hard."

:)

I'm going to pick up a Ducati lower end (offered at a very low price as the person has a literal heap of them) tomorrow for inspection.

I've also got a new 2017 250 crank and a set of lightly used matching counterbalancer and dual pinion primary gear coming and I'll be interested to see how the balance factor is done.

thanks,
Michael

Michael talk to flet and also read Bradleys First book it explains it all.
http://www.tz350.net/images/booksvids/john_bradley_the_racing_motorcycle.jpg

[Michael Moore]

husaberg, as John's former North American distributor for Volumes 1 & 2 I have read his short chapter (with photos) on gears, but I'm sure John would agree there's only so far he can go in approx 10-15 pages, and he finishes with the admonition that once things have been modified seeking specialist help is probably needed. I've got three "home shop machinist" books of 50-150 pages each on gear making and Machinerys Handbook has 211 pages on gears and I have two different gear software packages that allow some pretty strange looking gears to be made, and if it were dead simple people wouldn't spend entire apprenticeships learning about it.

If every gear in use was an unmodified and completely "standard" gear things might be a bit different, but I've been assured by someone who did an apprenticeship as a gear maker that is not the case in the motorcycle industry. Some manufacturers are "pretty good" on using standard Module gears as long as they fit the job, others mix and match DP and Module as they see a need, and others do whatever they please when they please to get what they want.

It is a complicated subject and while I could probably make a basic gear for some application with not very stringent requirements (like the Honda oil pump drive gear I machined from wax that seems pretty close to what Honda did, though it was not a "standard" gear by the time I got things to match under magnification), motorsports transmission gears are likely to be a different kettle of fish. Maybe the KTM gears that would be changed to improve ratios are dead standard unmodified gear forms that can easily be slightly changed on total tooth count for a pair (one up, one down so the total number of teeth remain the same). But on the XC ratios I see total tooth counts for the pairs of 46, 41, 45, 45, 47 and 46 so I'm pretty doubtful everything there is an ideal "standard" gear.

Frames seem easy by comparison.

cheers,
Michael

[husaberg]

husaberg, as John's former North American distributor for Volumes 1 & 2 I have read his short chapter (with photos) on gears, but I'm sure John would agree there's only so far he can go in approx 10-15 pages, and he finishes with the admonition that once things have been modified seeking specialist help is probably needed. I've got three "home shop machinist" books of 50-150 pages each on gear making and Machinerys Handbook has 211 pages on gears and I have two different gear software packages that allow some pretty strange looking gears to be made, and if it were dead simple people wouldn't spend entire apprenticeships learning about it.

If every gear in use was an unmodified and completely "standard" gear things might be a bit different, but I've been assured by someone who did an apprenticeship as a gear maker that is not the case in the motorcycle industry. Some manufacturers are "pretty good" on using standard Module gears as long as they fit the job, others mix and match DP and Module as they see a need, and others do whatever they please when they please to get what they want.

It is a complicated subject and while I could probably make a basic gear for some application with not very stringent requirements (like the Honda oil pump drive gear I machined from wax that seems pretty close to what Honda did, though it was not a "standard" gear by the time I got things to match under magnification), motorsports transmission gears are likely to be a different kettle of fish. Maybe the KTM gears that would be changed to improve ratios are dead standard unmodified gear forms that can easily be slightly changed on total tooth count for a pair (one up, one down so the total number of teeth remain the same). But on the XC ratios I see total tooth counts for the pairs of 46, 41, 45, 45, 47 and 46 so I'm pretty doubtful everything there is an ideal "standard" gear.

Frames seem easy by comparison.

cheers,
Michael

I didn't mean to be flippent What i was meaning is it covers the multiple use common ones used and the way to calculate forms.
Flettner here makes gearboxs for a living, i guess that kind of makes him qualified. But as far as i know he sticks to simple is best. and mostly uses a ready made gearbox
The book includes examples like Honda 750 using 4 diferent modules and the KR1 the same
as you said to lose a tooth or two they mod the profile but often they just use a totally different module,

But using the Nova T20 first gear conversion as an example its possible to go even further.

The first gear, which is too low for racing anyway, I replaced with a brand new higher ratio gear. This can be done quite easily. All you do is replace the 36t gear with a 33t one! The cut angle is different so it allows for only one gear to be changed! Engineers out there will be telling me that this is impossible, but it is a common conversion, it works, and I've done it! These are manufactured in batches of 10 by Nova Racing. Martin Crooks is always prepared to order a new batch to be made up, if he gets sufficient orders (5 or 6). Through this site, we managed to get enough orders (I bought two - one for each engine) and this is now fitted and working.
http://www.t20suzuki.com/racepic/higear.jpg


I spent a fair bit of time once going through Kawaski parts fiches looking for gear ratios for KE/KS 125 there were about 30 or more combinations just through model changes and updates
Bradleys 15 pages is better than anything available on the Net i have ever found.

There was another place that used to do the mix and match gears in the UK but i think Nova took over them.

EDIT i think it was Nova trading as G Dyson previously.

Mr Francis Payart posts occasionally and i assume he makes his own gearboxs you could try him.

i did find this though
https://grabcad.com/library/involute-gear-design-from-scratch-1

https://khkgears.net/new/gear_knowledge/gear_technical_reference/calculation_gear_dimensions.html
https://khkgears.net/new/gear_calculator.html
Toothed belt drive primary and CVT is far more appealing by the minute

here is a KTM125SX i found on Ebay plus the tooth count
340363

[_____]

.. as John's former North American distributor for Volumes 1 & 2...
Michael

Hi Michael,
is there any chance that there will be a reprint of the series? I am happy enough to own Volume 1 & 2 and was recommending it to friends.
Since they are not available anymore the prices on amazon have been skyrocketing. They are billing ten times higher than what I have paid (was ~50-80, cant recall. Now 600€! Each!)

On topic of changing a single gear: That works. I know that from a friend of mine who does Vespa tuning.
They change the primary gear ratio with up to four different small teeth numbers with the same pinion and it works. Profile shift is the keyword.

Cheers
Chris

[Flettner]

I cut my own gears, here a plastic oil pump / water pump drive gear.
A David Brown gear hobb.
Some I make in 4140 and get them nitrided, counter balance drives etc.
Others I do in EN39B and get them case hardened, mostly heavily loaded gears, gearbox and the like.

[fpayart]

Hello,

Indeed, Flettner seems to know what he's talking about.
The design and manufacture of gears, is a very specific job.
We are starting to have a good experience in this activity.

We outsource a part of the production of our gears.
But we buy most of the different ratios at ROTAX.

One of the main difficulties, when designing a gearbox, is that the center distance of the shafts, is contant.
To change the ratio, it is necessary to change the number of teeth and the module and most of the time, to apply a teeth correction factor.
Care must be taken to maintain a sufficient driving rate and to balance the specific sliding of each gear.
Specific software is welcome ...

Then, during manufacture, the painful problem of heat treatments arises.
This is the most difficult point to master.
We had a lot of problems with our subcontractors.

Cheers,
Francis.

[OopsClunkThud]

On topic of changing a single gear: That works. I know that from a friend of mine who does Vespa tuning.
They change the primary gear ratio with up to four different small teeth numbers with the same pinion and it works. Profile shift is the keyword.


Changing a single gear in a set will still mesh, but it changes the angle the teeth contact at and all the forces related to that. Yes many vespa tuners do it, and then when the cases crack they take that as proof of power output...

[lohring]

We solved a variable ratio gearing problem with rear differential quick change gear sets. They are inexpensive and come in various ratios. We used it to increase the motor rpm from around 5,000 to 10,000 rpm that our prop liked. We played with the ratio for the best speed. The electric hydro went 98+ mph in 2008, still the fastest electric boat official record.

Lohring Miller

340369 340368

[Michael Moore]

Thanks for the examples of gears not being a trivial thing the typical home machinist (and I'm not a particularly good one) just knocks out.

Chris, your friends could help John's volumes 1 and 2 get back into print by purchasing a copy of volume 3

http://www.broadlandleisure.com/

John is aware of the demand for the earlier books, but since the printer who did them went bust and the plates were destroyed he's got a fair amount of work in order to do to reprint. Right now he's staying busy selling/packing/shipping the new book, and money from sales of that (and a reduction in the pallets of books cluttering up his house) will be needed for a final print of the other books.

Volume 3 easily equals the quality of the first two books, but it demonstrates that, as with gears, if you want to set up a bike at a "pro" level you need to be prepared to do some study and put in the work.

cheers,
Michael

[yatasaki]

I cut my own gears, here a plastic oil pump / water pump drive gear.
A David Brown gear hobb.
Some I make in 4140 and get them nitrided, counter balance drives etc.
Others I do in EN39B and get them case hardened, mostly heavily loaded gears, gearbox and the like.
Used to work on hobbing mill in secondary school, ten times, at least, faster than milling with index head and module cutter

[DoldGuy]

I've got a 2015 KTM 250SX engine and the 5 speed has a larger, instead of smaller, % drop from 4->5. I can put an entire 6 speed from an XC (not the XC-W) in and it would be an improvement but the 3rd through 6th % drops are kind of wide, all of them more than the typical Ducati (and 5->6 looks to be about 25-30% wider than would be appropriate for higher speed track use).

A complete new XC box is about US$900 for the gears/shafts/clips/shims plus the drum/forks add another $100-200. I looked at the 2013 250 SX-F fiche and that 6 speed seems possible on the ratios but it has a few bushings and I don't know if it is a drop in. The 2T 250/350 share transmissions with the 350 4T but I can't find any significant interchange with the 250-F, and later Fs are 5 speed.

FWIW, the 250SX 5 speed drops are 20, 16.7, 14.3 and 16.5% from bottom to top.
A 350 Bultaco/AJR is 25, 17, 15 and 8.
The XC has 24.4, 20, 16.4, 15.8 and 12.6% so 6th could be closer to 5th.
The "small" Duc standard street 6 speed (not the high first gear Corse) is 32.3, 20, 15.2, 11.5 and 7.7. The Duc Corse is pretty much the same but with a 28% drop when shifting to 2nd.
I have a 2003 TZ250 as 25.6, 16.1, 11.9, 8.3 and 7.4%

Those Ducati ratios look pretty good to me and are used in a good 10+ years of recent models and are plentiful on eBay. But that means making new crank cases, which could be a fun project and also let me see about adding a balance shaft, but it pushes a running bike even farther into the already hazy future.


Yes, it may well be that for the few times it gets run as a track day bike (if I get it built) the 5 speed with a fairly standard MX tune (I bought a Pro Circuit chamber that is supposed to maintain the 50 hp peak for another 1000-1500 RPM) will be fine for my mediocre riding skills, and the XC would be better. But even though I'm transitioning to "former racer" I still like to have things the way I think they ought to be. I wish I'd known more about KTM when I bought this engine, and was clairvoyant so I could see that they'd be adding an effective balance shaft in the major engine redesign for 2017. Neil's transfer port injection which is on some new KTMs would be nice to have too. :)

Greg, I was surprised when I looked at late Yam/Kawa/Suzuki 600 part fiches as they were my first though on possible donors. Not only are the idlers generally running on a bush (separate from the gear) but some of those bushes have internal splines to keep them from spinning on the shafts, which I'd never seen before. I looked at some photos of the parts on eBay to verify it wasn't just needle bearing details being left off the drawing. In some you can see the internal oil grooves and drillings to let oil get out to the bush/gear interface.

The TT Industries parts do have a good reputation, but isn't everything they do for pre-unit British stuff?

An XC 6 speed with tighter custom 5th and 6th gears would most likely be fine, if it was possible to get those gears designed and made at an affordable price. But for the price of those gears (and probably for less) I can get a complete Duc lower end and have clutch and primary gears too, as well as no special replacement parts.

A pal sent some primary gear parts to Ellis Moore at Moore Engineering in England to get some parts made but he told me that Ellis had a race crash last year that left him paralyzed from the chest down and he's closed his shop and his parts are coming back. Ellis was keen on one-off stuff (which Nova is not) and appears to have supplied high-quality parts at reasonable prices so his accident is a loss to the industry (as well as being tragic, I know other racers who've ended up in wheelchairs).

A friend who purchased a TZ125 last year has been telling me of some major parts that aren't to be found as NOS, and now that I'm done with vintage bikes I'd like my remaining projects to not involve massive part searches. It is difficult enough to finish things without getting hung up on "wish I could find a new one of these" issues.

So when I saw various cool 125-250 shifter kart motors of modern manufacture it had me wondering what they are doing for gearboxes, and this seemed like the place mostly likely to have someone who knows.

cheers,
Michael

Michael,

I have a 300xc 6 speed & a 250sx 5 speed. I prefer the 6 speed ratios & feel the 5 speed is limited to just moto and have collected most components to convert it over to a 6 speed. Have spent a bit of time researching what fits (I’m Cheap), if I can help, let me know.

Curious, did you get the EngMod file from Wobbly? If so, how far off is the later model cylinders?

[Michael Moore]

Michael,

I have a 300xc 6 speed & a 250sx 5 speed. I prefer the 6 speed ratios & feel the 5 speed is limited to just moto and have collected most components to convert it over to a 6 speed. Have spent a bit of time researching what fits (I’m Cheap), if I can help, let me know.

Curious, did you get the EngMod file from Wobbly? If so, how far off is the later model cylinders?

Thanks for the offer, I've got all the part numbers for the XC recorded. Online parts fiche are sooooo useful, and the "where does this part fit?" searches often give some interesting information.

I've not taken the SX engine apart so wobbly's EndMod info is sitting, ready to spring to action at some point, and I'll rope Jeff Henise in on the EngMod stuff (he has a 300XC of the Husky flavor).

I now have a 2009 M696 Ducati lower end assembly (crankcase damaged by the side stand) sitting in the garage and I'll start cleaning/disassembling/modeling transmission/clutch/primary drive bits soon. FWIW the dry clutch uses 4 more plates than the SX wet clutch but the friction plates are twice the thickness so the 52.4mm stack is 25mm thicker than the KTM.

I looked at that PowerCDI site mentioned in the Speeduino thread and read some reviews by people who tried it and it sounds interesting, especially since there's going to be (or is) one for the TPI engines. I've got a new 38mm PWK Stryker (which I understand isn't universally liked) on hand but going to Neil's TPI system ;) sounds appealing and I could see buying a PowerCDI if it proves out as I will not be surprised if I have to spend money anyway to get a different ignition curve from the SX for paved track use.

cheers,
Michael

[TZ350]

.
Flettner originally suggested this approach to me.

The 2S-MAP changes from about 0.4bar to 1.40bar, but not very smoothly. As the motor is not running that great. So at this point I can't tell how useful the two stroke pseudo MAP results are going to be.

Still it is great to have something to continue working with and I will know more in a few days hopefully. With any luck I will be able to get the motor running better and be able to log some data. That should tell me if I am on the right track with my ideas about getting a usable two stroke MAP value that indicates real airflow through the motor. It is such hard work making "reality" conform to "theory" ........... :lol:


Ok ...... I now claim for Myself and Flettner this working 2S MAP indication of air flow for 2S EFI, as a world first.
Happy to be proved wrong about being first, but you will have to show a link that includes technical details, and a picture(s).


The difference between high/low 2S crankcase pressure displayed/used as a MAP value for 2S EFI. Time will tell if this is a good useful indicator of air flow like a 4S manifold MAP sensor is for 4S EFI.


<iframe width="560" height="315" src="https://www.youtube.com/embed/Ml7dmxb8ghw" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

A big thanks to Flettner as I managed to get to here by following a path he suggested.

More on this 2S EFI project can be found here:- https://www.kiwibiker.co.nz/forums/showthread.php/185773-Speeduino-2T-EFI-Project
.

[husaberg]

Thanks for the offer, I've got all the part numbers for the XC recorded. Online parts fiche are sooooo useful, and the "where does this part fit?" searches often give some interesting information.

I've not taken the SX engine apart so wobbly's EndMod info is sitting, ready to spring to action at some point, and I'll rope Jeff Henise in on the EngMod stuff (he has a 300XC of the Husky flavor).

I now have a 2009 M696 Ducati lower end assembly (crankcase damaged by the side stand) sitting in the garage and I'll start cleaning/disassembling/modeling transmission/clutch/primary drive bits soon. FWIW the dry clutch uses 4 more plates than the SX wet clutch but the friction plates are twice the thickness so the 52.4mm stack is 25mm thicker than the KTM.

I looked at that PowerCDI site mentioned in the Speeduino thread and read some reviews by people who tried it and it sounds interesting, especially since there's going to be (or is) one for the TPI engines. I've got a new 38mm PWK Stryker (which I understand isn't universally liked) on hand but going to Neil's TPI system ;) sounds appealing and I could see buying a PowerCDI if it proves out as I will not be surprised if I have to spend money anyway to get a different ignition curve from the SX for paved track use.

cheers,
Michael
Ian Cramp used a 851/916 gearbox on Loinheart i know he had the tooth pattern deciphered for the primary drive it was some oddball pressure angle only Ducati used i have his email somewhere,
I think i have the company's name that made the primary gear for Lionheart but i recall it was very spendy even back then. i believe they had to make the tooling to make the gear. I doubt Ducati would have changed the gear designs in the interim.

Here you go
assuming its the same 2.25 modulus 15 degree pressure angle and i guess he might still have the tool still. seeing it was about $800 USD then plus about 1500 us for the two complete small primary gears
Tay Tool work analysed it
M&B gears made them.
Let me know if you want his email
340372340373340374340375340376340377

another to talk to would be The V Two people which i guess Ken will know.
They made primary gears for bevel racing Ducatis but i suspect they might have used a more traditional gear.

[Michael Moore]

This 696 is a wet clutch motor.

The Duc primary pinion gear OD matches a standard Mod 2.32(ish) which seems an unlikely number.

The basket uses 3 rivets to attach it to the clutch primary gear, and that gear has a bearing that runs on the mainshaft. So it might be that the KTM (or other) gear could be substituted as seems appropriate. I haven't gotten the KTM primary pinion in yet so I haven't been able to compare it to the Ducati. If the Duc clutch gear needs to be retained then maybe the KTM and Ducati pinions can be grafted together, or since I think the KTM is a straight plain bore with a key to drive the crank, a straight bore/tapered OD with key slot sleeve (which might be a straight-foward lathe part) could be used between the KTM crank and the Ducati pinion.

Once I pull a KTM clutch plate I'll be able to compare that to the Ducati for effective radius (including the changed primary ratio) to see if the Ducati clutch could be modified to use fewer plates which would narrow it up and save a little weight. The Ducati primary gears might be narrowed up a lot too, the dual gear (cam drive) pinion is a hefty chunk of steel.

There's lots of investigation still to happen.

cheers,
Michael

[_____]

Thanks for the examples of gears not being a trivial thing the typical home machinist (and I'm not a particularly good one) just knocks out.

Chris, your friends could help John's volumes 1 and 2 get back into print by purchasing a copy of volume 3

http://www.broadlandleisure.com/

John is aware of the demand for the earlier books, but since the printer who did them went bust and the plates were destroyed he's got a fair amount of work in order to do to reprint. Right now he's staying busy selling/packing/shipping the new book, and money from sales of that (and a reduction in the pallets of books cluttering up his house) will be needed for a final print of the other books.

Volume 3 easily equals the quality of the first two books, but it demonstrates that, as with gears, if you want to set up a bike at a "pro" level you need to be prepared to do some study and put in the work.

cheers,
Michael

Aw cheez! That are great news! I will buy the third one right away. Thanks a lot!

[Flettner]

Gears, yes, hardening is an issue.
I pre machine the blanks close to size then get them stress relieved
Then cut the teeth to a finished size minus about 0.02mm, in hardening process the blank will grow approx 0.02mm.
If the carborising is done properly ( along with the stress relieveing) the distortion will be very little in the hardening process. Finish is, clock the teeth concentric in the cylindrical grinder then grind to finished size, be it shaft or bore. This is for EN39B, hardness 60 Rockwell.
Or to put in technical terms, fucken hard.

Good to see TZ has cracked the EFI nut, FAB.

[yatasaki]

Flettner, do you use gas or salt? We always use to go in plus for the blanks for outer diameter/gears, then exceed carburising over that plus into the material core, and, after stress relieving grinding to final measure.
We used sodium cyanide.

[Flettner]

don't know if there would be any cyanide baths in NZ still, you know, health and safety.
Carborising done by gas.

[flyonly]

I am interested in people’s opinion on 10mm spark plugs for a 50cc. I was thinking Brisk Silver racing.


Sent from my iPhone using Tapatalk

[husaberg]

don't know if there would be any cyanide baths in NZ still, you know, health and safety.
Carborising done by gas.

There is a great story in George Beggs book about Bert Munro and the Cyanide baths at some engineering firm in Invergiggle
they warned him it had to be 100% dry before he put it back in. Even pointed to the sign that said just that.
he just nodded . As he he used to often call in and use their gear they left him to it
But Bert i guess was in a Hurry
They heard the bang but couldn't find Bert they looked in the toilets here he was in the stink trying desperately to put his on still on fire hair out.

I dont think he quite understood the belts and braces safety philosophy.
He got rid of the belt drive in the 1930's and the braces were for holding up his pants
https://i.ytimg.com/vi/m_L1e2K71uw/hqdefault.jpg

[yatasaki]

Baths were switched off in 1998, for health reasons, salt went solid, chiseled out ,and thrown away...so sad story...
Flettner, do you quench imediatelly after carburising?

[dutchpower]

Neels (vannik )

Can you tell me more about how de design in Engmot of the exhaust pipe calculate ( simulate )
Everytime this shape appear 25 / 50 / 65 / 125 etc. as the best !!!!

[Vannik]

Neels (vannik )

Can you tell me more about how de design in Engmot of the exhaust pipe calculate ( simulate )
Everytime this shape appear 25 / 50/ 65 / 125 etc. as the best !!!!

DutchPower, I do not fully understand your question:


Do you ask why, after a number of simulation runs and development, the best pipe looks like the picture,
Or do you ask why Dat2T always gives the same starting pipe?

[dutchpower]

No 1 Neels

[Vannik]

DutchPower, I do not fully understand your question:


Do you ask why, after a number of simulation runs and development, the best pipe looks like the picture,
Or do you ask why Dat2T always gives the same starting pipe?



No 1 Neels

That is like asking why the optimum is the optimum, I will try:

Our current understanding of the inlet, scavenging, exhaust duct shape and pumping optimums lead us to an engine with a certain type of port layout and size (mostly derived from Jan's work on the RSA125), and this layout requires specific suction and plugging pulses from the pipe with a specific phasing and strength to make it all work together. This basic exhaust layout gives you that.

For a less than optimum engine, for instance the TM KZ10C which has a fixed timing curve prescribed by the rules, we see some deviations from this "optimum" shape, to compensate for the less than optimum condition. I am sure that as scavenging, selective cooling, exhaust ducts etc develops further this optimum shape will drift to a new shape.

Does this answer your question?

[dutchpower]

Oke Neels

Only asking because it works well by some engines ( ktm 65 '19 ) and others not
And the port layout of the ktm are not so good ( wobbly )

[koenich]

out of curiosity - does the program have an optimizer which automatically iterates to the 'best' pipe?

[Vannik]

out of curiosity - does the program have an optimizer which automatically iterates to the 'best' pipe?

No, it is something that is planned but it will have to follow making the software parallel processing, otherwise it will run for weeks.

[peewee]

just a small update. got a new torch and continued on from when the other one broke. next step now is just a bit of grinding it down and put on the outer shell. seems like its taking along time just to make small progress :brick:

[TZ350]

... seems like its taking along time just to make small progress :brick:

I think most of us can relate to that..... :( ...... we are looking forward to the result of all your good work. :niceone:

[2T Institute]

A bit OT, but who (besides Nova) is making 2T race transmissions? Do the shifter kart engine manufacturers do them in house or are there a few "standard" sources that provide them to the OEMs?

It used to be that if you wanted a race transmission you could start with an RD/RZ and drop TZ parts in, or go to your local dealer and buy RS125/TZ125 parts, or maybe pick up something from a 125/250 Rotax race engine. But all those engines have been out of production for 10-25 years now.

I've heard that the NSF250R is basically using the late RS125 box, but I don't know how available bits from something like that would be, especially here in the US where GP racing is pretty much dead.

At one time in Italy you could become a m/c manufacturer by shopping at Minarelli/Franco Morini for engine, Dell'Orto for carb, Verlicchi for a frame, Grimeca for wheels, Marzocchi or several others for suspension, CEV/Aprilia for electrics etc etc and then just assemble the parts. Do the modern 2T race engine makers have a race transmission company they shop at who can supply "off the shelf" turn key primary drives/transmissions?

Many of the modern 4T transmissions have plain bearings and need a pressure oil feed to them (but not Ducati, as used in the Tularis 2T twin special) so they are not suitable for easy grafting in to a DIY project unless an oil pump is added. A transmission/clutch sized for the torque spikes of an 1100 Duc twin seems like it might be overkill (though strong) for a 125-250 2T engine. But the Ducati looks like it is about the main option for a readily available and affordable gearbox clutch for an engine project. I suspect there are other options but I'm looking in the wrong places for them.

cheers,
Michael

Search Roberto Micozzi on FB he speaks and types very good English, very nice work , great prices and service

https://www.facebook.com/MicozziIngranaggi

Thanks for letting us know about Johns new book, these days Italy still seems to be the home of beautiful small scale manufacture of engines. Seen many of the RSA type scooter engines married to CVT's which seem to pump out serious hp, all housed in a old Vespa frame :drool:

[Michael Moore]

The photos on Micozzi's page look nice, and he seems to do work for a wide variety of marques. Thanks for the tip. I'm still in the early stages of looking at this Ducati gearbox.

cheers,
Michael

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/D3Ck0R1Ha_8" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Faces of the Isle of Man ...... :D

[karter444]

Hi Wobbly
is modifying the head on a kx10c to allow cooling over the whole insert better than no direct water cooling at all
great result for you on the weekend at the CIK meeting in hamilton
cheers Richard

[wobbly]

Thanks Richard , yea makes me laugh when all our opposition wreak gear by "tuning" on the stand.
I look at the Density Altitude on my phone and change jets 4 times a day, keeping the egt nailed at 650.
The C model insert can be cooled above the squish and around the plug only, by cutting a slot from front to rear in the cover.
If you think about it hard enough , you will see how not to be cooling the back of the chamber by doing this.

[F5 Dave]

I thought that them (we shared race days with buckets and karts) revving them out like crazy and braking on crotch high stands was an attempt to intimidate and distract other teams while their driver sat up in the car listening to Cyndi Lauper.

It's a wonder they are still allowed to do that as I imagine if a kid or careless person walked into a spinning wheel it would just be horrific.

[Michael Moore]

Honda did that in the 1960s. They'd line up the bikes on their stands with the exhausts aimed at the Yamaha pits and then start/warm them up. An unmuffled Honda 4/5/6 is quite loud.

[Matt@TYGA]

Honda did that in the 1960s. They'd line up the bikes on their stands with the exhausts aimed at the Yamaha pits and then start/warm them up. An unmuffled Honda 4/5/6 is quite loud.

Ho ho ho.

1998 All Jap Championship.......We were at Motegi working in the pit, when the HRC blokes in the pit next door fired up the Honda six for a couple of demo laps on the oval. Blimey!!! I thought an earthquake was upon us! :eek5:

[Frits Overmars]

...the HRC blokes in the pit next door fired up the Honda six for a couple of demo laps on the oval. Blimey!!! I thought an earthquake was upon us! :eek5:Yeah, the 250cc Honda-six was loud but it was musical loud; still one of my favorite engine sounds. It had so little crankshaft intertia that one had to be careful not to let the revs drop too much, even during upshifting:
https://www.youtube.com/watch?v=hjZWrvUGAV8

The 125cc Honda-five, though with only half the engine capacitiy of the six, was offensively loud. It could make you feel sick to the stomach, and that's not just a figure of speech. From a distance, it was quite entertaining though. I tried to attach its soundtrack here, but the forum software wouldn't let me, so I zipped it for ye.
340525 340526 340527

[Michael Moore]

My 216cc Honda twin vintage racer (based on a sloper CB175 engine) was measured at 130+ dB on open megaphones. There was no problem with people in the pits not getting out of the way when I was riding it to the grid.

The other people in the industrial park where the engine was built were used to the roar of race Z1 Kawasakis on the dyno and weren't bothered by that, but when the Honda was running one of the neighbors came over to find out what was making all the racket.

I'm not so keen on noise these days, and a friend's Zero e-moto is appealingly quiet.

[yatasaki]

How do you pick your final ratio for buckets?
One old karter around here told me to have max overrev on the final gear on the half of finish line.

..on the noise talk, once for carnival parade, I took the mufflers off my kr1s and fit megaphones one meter in length and 300mm exit diameter. The noise on the idle was really unpleasent 6m behind the bike.
When the bike was on the KIPS :cool: people from 7 km neighbour village were swearing hearing something like formula 1

[peewee]

determined to get this shit box running by summer so im sneaking to the garage every chance I get :woohoo:. a bit more grinding to do but im trying to have as much water around the passage as possible. extending it 2x the bore was a after thought, other wise I would of done things a bit different from the beginning but ill do the best I can with what I have to work with now without going backward to much

[karter444]

Thanks Richard , yea makes me laugh when all our opposition wreak gear by "tuning" on the stand.
I look at the Density Altitude on my phone and change jets 4 times a day, keeping the egt nailed at 650.
The C model insert can be cooled above the squish and around the plug only, by cutting a slot from front to rear in the cover.
If you think about it hard enough , you will see how not to be cooling the back of the chamber by doing this.

Hi Cheers for the reply , will try and work it out

[F5 Dave]

How do you pick your final ratio for buckets?
One old karter around here told me to have max overrev on the final gear on the half of finish line.

..on the noise talk, once for carnival parade, I took the mufflers off my kr1s and fit megaphones one meter in length and 300mm exit diameter. The noise on the idle was really unpleasent 6m behind the bike.
When the bike was on the KIPS :cool: people from 7 km neighbour village were swearing hearing something like formula 1
I start with max overrev at the end of the longest straight. But I don't stop there. I then consider my change points and relative acceleration compared with opponents as fastest lap time is not the entire picture although a good guide considering the first two points.

[_____]

determined to get this shit box running by summer so im sneaking to the garage every chance I get :woohoo:. a bit more grinding to do but im trying to have as much water around the passage as possible. extending it 2x the bore was a after thought, other wise I would of done things a bit different from the beginning but ill do the best I can with what I have to work with now without going backward to much

For the sake of science!
Could you make the exhaust port cooling seperated from the cylinder? So that you might use two different cooling circuits on the cylinder.
The idea of mine is you test the engine on the bench in two ways:
1. You cool the exhaust and the cylinder hereafter with coolant
2. You only cool the cylinder and leave the cooling circuit of the exhaust filled with air

Benefit: You'll see if it really is good to cool that much of the exhaust pipe or if it is just Ryger-ish snakeoil :cool:

Cheers
Chris

[Michael Moore]

yatasaki, it can be good to have the bike geared a little bit higher than you expect to use (not lose), so that you are able to go faster if you get a tailwind or a tow by slipstreaming a faster rider/bike.

[peewee]

For the sake of science!
Could you make the exhaust port cooling seperated from the cylinder? So that you might use two different cooling circuits on the cylinder.
The idea of mine is you test the engine on the bench in two ways:
1. You cool the exhaust and the cylinder hereafter with coolant
2. You only cool the cylinder and leave the cooling circuit of the exhaust filled with air

Benefit: You'll see if it really is good to cool that much of the exhaust pipe or if it is just Ryger-ish snakeoil :cool:

Cheers
Chris

i dont have a dyno for testing unfortunatly. i was going to use a larger shell around the exh passage but i thought that might cool the exh to much so i decided to use a smaller shell

[wobbly]

Plenty of work has already been done on this with no good results.
Firstly Jan filled in under the Ex duct to reduce the coolant flow - result deto city.
Secondly, I ceramic coated the duct inside surface , result lost power - deto city.
Third,Franco at TM tried the air gap shell idea, result - deto city.
Fourth,TM originally designed the KZ10 with all the coolant flow entering the cylinder under the duct.
This heats up ALL the water ,including that flowing over the transfer tops.
They later plugged the holes and directed all the water into the cylinder , from the side over the top of the duct.
This gave better power.
Lastly I bored a hole into the water jacket above the boost port , so all the cold water flowed over the transfers first.
Then added two 3mm holes thru the plugs under the Ex duct to help cool this area separately.
Result just over 1 Hp in 48 , with alot less deto level when under full power.
But the CIK and NZ techo guys would not allow this " additional " water circuit.
Moral of the ( long ) story is that cooling the duct first is bad , as is not cooling it at all , as you must keep the retained
mixture in front of the piston as cool as is possible to prevent the returning stuffing wave from pushing hot gas back into the cylinder.

[peewee]

Plenty of work has already been done on this with no good results.
Firstly Jan filled in under the Ex duct to reduce the coolant flow - result deto city.
Secondly, I ceramic coated the duct inside surface , result lost power - deto city.
Third,Franco at TM tried the air gap shell idea, result - deto city.
Fourth,TM originally designed the KZ10 with all the coolant flow entering the cylinder under the duct.
This heats up ALL the water ,including that flowing over the transfer tops.
They later plugged the holes and directed all the water into the cylinder , from the side over the top of the duct.
This gave better power.
Lastly I bored a hole into the water jacket above the boost port , so all the cold water flowed over the transfers first.
Then added two 3mm holes thru the plugs under the Ex duct to help cool this area separately.
Result just over 1 Hp in 48 , with alot less deto level when under full power.
But the CIK and NZ techo guys would not allow this " additional " water circuit.
Moral of the ( long ) story is that cooling the duct first is bad , as is not cooling it at all , as you must keep the retained
mixture in front of the piston as cool as is possible to prevent the returning stuffing wave from pushing hot gas back into the cylinder.

good info. my water routing has the duct cooled last. its not show in the photos but i was going to put a exit nipple at the end near where the exh spigot attaches

[yatasaki]

yatasaki, it can be good to have the bike geared a little bit higher than you expect to use (not lose), so that you are able to go faster if you get a tailwind or a tow by slipstreaming a faster rider/bike.
On our last moped race last year I had 10600 rpm on the end of finish straight. This year had new cylinder which gave 600rpm more ie 11200 but for this reason tried front sprocket 12 instead last years 13. Max speed was a bit less but laps 2 seconds better. My opponent had longer (13 instead 12 sprocket) final ratio and couldn't keep up but he was accelerating untill end of straight..
Our last shifter race
https://youtu.be/zP39jrMTOGA
Skip to 08:08, me at the lead
My shifting to fifth(final gear) 08:17
His shifting to final 08:24

[Frits Overmars]

On our last moped race last year I had 10600 rpm on the end of finish straight. This year had new cylinder which gave 600rpm more ie 11200 but for this reason tried front sprocket 12 instead last years 13. Max speed was a bit less but laps 2 seconds better.There are no prices for top speed in road racing :msn-wink:.
Yatasaki, you seem to be riding a Tomos with forced air cooling. I don't know about your regulations, but if it is permitted, removing the fan and the cowling could liberate another HP.

[Michael Moore]

As with so many things, gearing may often be a compromise. As long as your lap times decreased it sounds like you didn't do bad on your gearing choice. It all comes down to the bike/track and weather conditions.

For example, if you gear for max safe RPM in top on the back straight (which at almost 1/2 mile in length is very long on a small bike so you are flat out for quite a while) at Willow Springs in the morning when the air is still, you may find yourself closing the throttle some in the afternoon to avoid floating the valves if (very likely when in the spring) a 20-35 mph tail wind comes along out of the west.

You need to do what works and YMMV.

cheers,
Michael

[yatasaki]

There are no prices for top speed in road racing :msn-wink:.
Yatasaki, you seem to be riding a Tomos with forced air cooling. I don't know about your regulations, but if it is permitted, removing the fan and the cowling could liberate another HP.
I could remove fan and cowling but cylinder head fins
Are to small for this move. Did another thing, as original bike spins around 6000 rpm, I cut every second fin on the fan. Heard from malossi scooter mechanic that every 5000 rpm fan takes around 1 hp.

Michael, on that track that very day we had some in-face excessive wind, when racing centrifugal clutch class. Than you shape yourself as a hedgehog..
Wind issues are more or less clear, but some theoretical/ideal gearing for given track I was wondering somebody has.

[F5 Dave]

Helmet mounted gopro must be worth -0.78kph.

[Frits Overmars]

... if you gear for max safe RPM in top on the back straight at Willow Springs in the morning when the air is still, you may find yourself closing the throttle some in the afternoon to avoid floating the valves if (very likely when in the spring) a 20-35 mph tail wind comes along out of the west. 'Closing the throttle some' may weaken the mixture because the needle will take over from the main jet. Sit up, stick your knees and elbows out, feather the front brake (that's what the MotoGP-jockeys do in order to put some more heat in their front tire) but whatever you do, do not roll the throttle back.
Two-strokes simply run out of breath if revved too high. so unless the gearing is way off, they are self-protecting, unlike some other contraptions I could name.
By the way, what 'floating' valves were you talking about Michael?
340545

[Frits Overmars]

I could remove fan and cowling but cylinder head fins are to small for this move.Your last picture showed engines with normal, unblown cooling fins. Isn't that allowed? And what about fitting a Tomos A55 cylinder? I think it looks quite promising, maybe even better than a Kreidler cylinder.
340547

[yatasaki]

Yep Frits, best aluminium tomos cylinder so far BUT, guy behind me (with the camera) has that cylinder and 50 cc, Slovenians claiming to extract 9 hp with dellorto sha14/12, and you can really see these 9hp on track. While I'm using a35 cast iron cylnder which is 60cc on my bike and can be bored to 46 bore (70+cc). Trick is to convert a35 cylinder (which is having to small Reeds)to piston induction.
More cc and square-easier power getting ..AND a lot of material and space for transfers and exhausts.
That a55 cylinder is on my bench right now as a 2nd engine, preparing for 4h endurance.

[guyhockley]

Laser honing

https://www.gehring-group.com/en-ww/laser-honing

(https://www.gehring-group.com/en-ww/laser-honing) It says: "the laser structuring of the cylinder is currently applied in the range of the upper piston reversal point." In the picture it looks like the right hand cylinder has been treated to a greater depth than the one next to it, where the pattern seems to stop without going full circle.

[F5 Dave]

Reduction in oil consumption
Improvement in emissions
Reduction in friction
Reduction in wear


Well the top one sounds useful. All my 2 strokes seem to use a lot of oil :psst:

[jamathi]

Plenty of work has already been done on this with no good results.
Firstly Jan filled in under the Ex duct to reduce the coolant flow - result deto city.
Secondly, I ceramic coated the duct inside surface , result lost power - deto city.
Third,Franco at TM tried the air gap shell idea, result - deto city.
Fourth,TM originally designed the KZ10 with all the coolant flow entering the cylinder under the duct.
This heats up ALL the water ,including that flowing over the transfer tops.
They later plugged the holes and directed all the water into the cylinder , from the side over the top of the duct.
This gave better power.
Lastly I bored a hole into the water jacket above the boost port , so all the cold water flowed over the transfers first.
Then added two 3mm holes thru the plugs under the Ex duct to help cool this area separately.
Result just over 1 Hp in 48 , with alot less deto level when under full power.
But the CIK and NZ techo guys would not allow this " additional " water circuit.
Moral of the ( long ) story is that cooling the duct first is bad , as is not cooling it at all , as you must keep the retained
mixture in front of the piston as cool as is possible to prevent the returning stuffing wave from pushing hot gas back into the cylinder.

Hello Wayne

Does the TM have a mechanical water pump, or is it rear axle driven?
And what do you use on your dyno?
There may be a big difference in the water circulation speed between TM and RSA.
On the RSA the pump from the 250 was used.
It caused some power loss, but the net result was still positive!
The circulation speed was very high

[Frits Overmars]

Wob, here are the dimensions of the Rotax-129 impeller as used on the Aprilia RSW125, and the Aprilia RSW250-impeller as used on the RSA125,
that circulated 60 litres per minute.
340568

[husaberg]

Wob, here are the dimensions of the Rotax-129 impeller as used on the Aprilia RSW125, and the Aprilia RSW250-impeller as used on the RSA125,
that circulated 60 litres per minute.
340568

Compared to the sound of a swarm of angry bees sound effect you get with the 65/85/125 MX classes here in NZ
The popping and Banging and farting the 250 and 450 Fours stroke MX make as the run on and off the limiter on the start line and over the jumps is hardly melodic

nice pump pics BTW

https://www.youtube.com/watch?v=3jsHjBKHtEk
https://www.youtube.com/watch?v=Mpjumg0t6u4

[wobbly]

Hello Jan, the karts use an axle driven pump , and we use a radiator area ( with an extra unit behind the seat ) sufficient to keep the engine at a max of 40* on the hottest day.
Going colder on the dyno has no effect on power - but does lower the background deto level a small amount.
The dyno has a programmed controller that heats the water to 30* , and then switches a big fan that keeps the water at 40* during a test.
The heat soak and then the temp rise time is sufficient to get the case/crank/gearbox/pipe up to working temp after about 6 all gear WOT runs.

[jamathi]

Hello Jan, the karts use an axle driven pump , and we use a radiator area ( with an extra unit behind the seat ) sufficient to keep the engine at a max of 40* on the hottest day.
Going colder on the dyno has no effect on power - but does lower the background deto level a small amount.
The dyno has a programmed controller that heats the water to 30* , and then switches a big fan that keeps the water at 40* during a test.
The heat soak and then the temp rise time is sufficient to get the case/crank/gearbox/pipe up to working temp after about 6 all gear WOT runs.

Very good system Wayne!
Testing at 40° gives 1-1,5 HP more than the 53° we used at Aprilia.
That is what we saw when testing from 90° to 40° with 5° intervals.
Why more than 50° on track was preferred by Mr Witteveen I don't know.....
I think he was afraid of 'cold seizures'
He considered a piston clearance of 0,04mm as VERY important.
But when I tried 0,06mm the engine gave more power!
I did this without telling anyone, as it was seen as pure heresy at Aprilia…..
Of course, after only one training session, piston clearance was 0,10-0,12mm.
So they kept changing pistons….

[jamathi]

Wob, here are the dimensions of the Rotax-129 impeller as used on the Aprilia RSW125, and the Aprilia RSW250-impeller as used on the RSA125,
that circulated 60 litres per minute.
340568

Hello Frits,

I don't remember if the water circulation was 60 or 160 litres per minute....
As those tests were done at Aprilia while I was still working at DERBI
In any case an electric pump was FAR insufficient with 20 litres per minute!
For a 125cc single.
I have no idea of the water circulation of a rear axle driven water pump.
But you CAN have insufficient cooling with a 40° water temperature I think.
You have to measure the temperature when the water goes into, and comes out of the cylinder to be sure.
The difference should be minimal.

[TZ350]

it´s my two stroke bike with speeduino https://youtu.be/zk55HR6bgO0



Great fuel injection project, I like it..... :drinknsin .... looks like more and more people are trying their hand at 2S EFI.

[Frits Overmars]

Hello Frits, I don't remember if the water circulation was 60 or 160 litres per minute.... As those tests were done at Aprilia while I was still working at DERBI. In any case an electric pump was FAR insufficient with 20 litres per minute for a 125cc single. I have no idea of the water circulation of a rear axle driven water pump.I hate rear axle driven water pumps. While you are on the starting grid, revving the engine, waiting for the flag to drop, there is no water circulation at all!
Kart engine manufacturers know that too, of course. They supply engines for amateur drivers with an engine-driven pump. So it is al the more surprising that their six-speed competition engines have no pump - with one exception: the DEA KZ125 from our friend Andrea degli Esposti. He's also the only one until now with a balance shaft in that type of engine.
340579 340580


Anyway, just look at the way many pumps are driven from the rear axle: with two O-rings. No way can you transmit enough power that way for sufficient pumping.
340578



But you CAN have insufficient cooling with a 40° water temperature I think. You have to measure the temperature when the water goes into, and comes out of the cylinder to be sure.
The difference should be minimal.Agreed. And even then things can go wrong.
I remember a Dutch tuner praising an aftermarket cylinder head set with insert and cover: "the water stays 6° cooler, so cooling must be much better".
I pointed out that the water stayed so much cooler because most of the insert's outer surface was shielded from the water by the head cover.
In other words: the head insert hardly got wet (a problem that still exists today with many of those aftermarket heads).
When he did not immediately get my drift, I pointed out that the water would stay even cooler if it was not pumped through the engine at all...

[katinas]

[QUOTE=Frits Overmars;1131123365] the DEA KZ125 from our friend Andrea degli Esposti. He's also the only one until now with a balance shaft in that type of engine.
340579 340580

Hi Frits, interesting whether the whole cooling liquid enters the cylinder from 'under exhaust' side on this engine. Very nice additional cylinder clamping bolts, but sometimes on multi cylinder engines there is no space to do this.

Looks, that Honda used small cooling hole through narrow EX divider on late Aoyama cylinders and maybe last NSR 500.

[dtenney]

Very good system Wayne!
Testing at 40° gives 1-1,5 HP more than the 53° we used at Aprilia.
That is what we saw when testing from 90° to 40° with 5° intervals.
Why more than 50° on track was preferred by Mr Witteveen I don't know.....
I think he was afraid of 'cold seizures'
He considered a piston clearance of 0,04mm as VERY important.
But when I tried 0,06mm the engine gave more power!
I did this without telling anyone, as it was seen as pure heresy at Aprilia…..
Of course, after only one training session, piston clearance was 0,10-0,12mm.
So they kept changing pistons….

Shoud the cylinder and head both be cooled to the same temp? Assuming one has access to an unlimited supply of water, would it be beneficial to have separate cooling for the cylinder and the head?

[katinas]

The customer hecitate few months, now it is the last iteration. CNC machining would start next week. Thanks for interesting patents!




Hi, from my testing with suction directly to transfers ports on conventional engine, I noticed that power drops with very wide suction duration ( too high piston skirt edge, like in your schematic ). And this effects feels without blocking crankcase space.
Maybe, would be better start with longer skirt ( say, half of exhaust side skirt length ) and then shortening step by step.

[jbiplane]

Maybe, would be better start with longer skirt ( say, half of exhaust side skirt length ) and then shortening step by step.
Thanks for advice Katinas. Easy to follow it! I making big parts for pistons need order correct material like AA2018 AA2218 AA2618
Or may be for CNC mill without forging there is better materials...

BTW want to ask comunity for advice how correctly port Yamaha BWS100 and Suzuki ad 110? May be discussed somethere...

[Pavel Myslik]

I could remove fan and cowling but cylinder head fins
Are to small for this move. Did another thing, as original bike spins around 6000 rpm, I cut every second fin on the fan. Heard from malossi scooter mechanic that every 5000 rpm fan takes around 1 hp.

Michael, on that track that very day we had some in-face excessive wind, when racing centrifugal clutch class. Than you shape yourself as a hedgehog..
Wind issues are more or less clear, but some theoretical/ideal gearing for given track I was wondering somebody has.

I am always setting my gearing so the engine will be overreved in the fastest point of the track or a couple meters before. This is usually at the end of the longest straight. I am racing little 50cc bike with 3 speed gearbox and using the 2nd gear for most of the corners so then I check that in the slowest corner the rpm don't drop from the "powerband" and acceleration from the corner suffers. Then it is simply a compromise.
I have found out that changing the sprocket on the engine by 1 tooth makes too much of a difference so I have a set of rear wheel sprockets which differs only by 1 tooth. When I have final ratio for the qualification I then use 1 tooth bigger = "slower" sprocket for the race because you might be forced to ride at defensive line or somebody will be blocking you and your corner speed will drop and so the rpm. Engine can handle the overrev if you will have clear track ahead.
Setting the ratio litlle longer and using the tow of a faster rider might be a good strategy too but I think this depends on the speed you are racing at. In my case top speed is little over 80 kph.

[Frits Overmars]

the DEA KZ125 from our friend Andrea degli Esposti. He's also the only one until now with a balance shaft in that type of engine.
Hi Frits, interesting whether the whole cooling liquid enters the cylinder from 'under exhaust' side on this engine.Yes, all coolant enters the DEA cylinder under the exhaust; there is no other water connection anywhere on the cylinder.
340586


Looks, that Honda used small cooling hole through narrow EX divider on late Aoyama cylinder and maybe last NSR 500.Yes, that is correct Katinas. I have some better images at home, but I'm not at home. Maybe just as well, because I'm not supposed to have those images :rolleyes:.


Setting the ratio little longer and using the tow of a faster rider might be a good strategy too...That reminds me of a similar remark by a Garelli rider: "Maybe we should gear it one tooth faster; that could be helpful in slipstreaming".
To which Jan Thiel simply replied: "Who do you want to slipstream?" (the Garellis were unbeatable for six years in a row).

[Michael Moore]

To which Jan Thiel simply replied: "Who do you want to slipstream?" (the Garellis were unbeatable for six years in a row).

For many of us the answer to that would be "all those faster people who keep passing me throughout the race".

The needs of a top rider on a top bike may not be quite the same as a mid-pack rider on a mid-pack bike, but I can't say for sure since I've never been a top rider on a top bike.

:)

cheers,
Michael

[wobbly]

Coolant temp is a complex combination of factors and depends alot on how much good technology is being used.
Way back I used a twin route water system on Champ winning Jetski engines.
The block was kept at 40* and the head was kept at 80* , this gave the best power but was very "on the edge " all the time re deto.
But this was before I understood the relative importance of what should be cold , what should be hot , and why.
Running the head hot , was conforming to the idea that the reduced temp delta would keep more energy within the combustion process , thus expanding the gas more and pushing down harder on the piston.
But Jan showed us the way forward , by allowing water close to the plug threads , keeping the sparkplug body cool , and thus reducing deto sensitivity.
The next step was doing the same thing with the squishband area - over cooling this area keeps the boundary layer surrounding the end gases cooler , again keeping deto at bay.
TM's head surrounds the chamber itself with a large mass of " insulator " material as part of the cover.
They even have an air gap , to keep the chamber area even hotter.
It is possible to combine both philosophy's , that is keeping the chamber surface itself hotter , but over cooling the plug threads and the squish area to retard deto sensitivity.
But that is a secret im keeping for now.
I have a pic of an interim solution , i will find it and post.

[wobbly]

Here is pic of partial solution for the TM cylinder.
Cold water is squirted back over the transfer tops, with only small holes under the Exhaust duct cooling that with flow direct from the case below.

[husaberg]

Yes, all coolant enters the DEA cylinder under the exhaust; there is no other water connection anywhere on the cylinder.
340586

Yes, that is correct Katinas. I have some better images at home, but I'm not at home. Maybe just as well, because I'm not supposed to have those images :rolleyes:.

That reminds me of a similar remark by a Garelli rider: "Maybe we should gear it one tooth faster; that could be helpful in slipstreaming".
To which Jan Thiel simply replied: "Who do you want to slipstream?" (the Garellis were unbeatable for six years in a row).

I think he got that from his Aprilia inspired version
340589
You mention the Honda from memory either the NSR250 road bike or the NSR125 had it flowing below the EX port but the racers didn't
340591340592340593
edit i think its both but the water feeds into the crankcase of the 250 and the side of the cylinder on the 125 but that could be fixed

Kennys Roberts designers got it right.
340590

[wobbly]

No, King Kennys boys ( Sinclair et al ) simply copied what Yamaha were doing at the time in GP - even the transfer ducts were carbon copies.
From my testing the best solution is cold water in over the boost port, flowing forward over the transfer tops.
Then the Ex duct cooled from below with small holes , the two flows meeting above the Exhaust duct and into the head.
Old Honda NF4 cylinders had the rear inlet , but no case cooling , so didnt have a separate duct flow.

[husaberg]

No, King Kennys boys ( Sinclair et al ) simply copied what Yamaha were doing at the time in GP - even the transfer ducts were carbon copies.
From my testing the best solution is cold water in over the boost port, flowing forward over the transfer tops.
Then the Ex duct cooled from below with small holes , the two flows meeting above the Exhaust duct and into the head.
Old Honda NF4 cylinders had the rear inlet , but no case cooling , so didnt have a separate duct flow.

I think the NSR250 has the holes at the rear but the NSR125 has none.
340594
The 250 ones have the holes though i think are blind recesses to the crankcase, but without access to a few i am only guessing and relying on memory
340601

the early RS's i think just followed the old CR design like this one they caried over from 84-87 on the cylinder reed and 88 on the case reed which is what i think the NF4 is
340598340600
Too be honest with you they likely did it this way as a production consideration as it saved a few mm of Rubber pipe.
It might also be the same reason the NSR125 goes to the front as that's where the water pump is mounted on them.:niceone:


The later RS125 NX4 though has the plug in the front i guess left over from Machining or might hint at road bike or multi use origins of the moulds.
it could be a core print but i doubt it.
340596340595

Kenny crew basically put Yamaha pipes and port spec into the RGV for JNR it had no more hp which upset Suzuki no end as they couldn't see the point until they showed them it lapped much much faster. that story came from Willing.

I hate rear axle driven water pumps. While you are on the starting grid, revving the engine, waiting for the flag to drop, there is no water circulation at all!
Kart engine manufacturers know that too, of course. They supply engines for amateur drivers with an engine-driven pump. So it is al the more surprising that their six-speed competition engines have no pump - with one exception: the DEA KZ125 from our friend Andrea degli Esposti. He's also the only one until now with a balance shaft in that type of engine.
340579 340580


.
Oddly Vortex do them for the non gearbox karts but not the gearbox class i even thought one of their old ones had them at one stage.
http://www.vortex-engines.com/download/fiche_ROK_GP.pdf

As does the Rotax max

[F5 Dave]

Just been out road testing my 500 in scorching wellington weather (anything over 20 degrees).

You don't know you are born. I have very compromised radiator area.

[F5 Dave]

For giggles;


I had huge bad surging on the 500 test ride last week.

So this weekend id try figure out the 500
Plugged it in to the laptop and revved it. Quickshifter goes Yes No Yes No. Ahhh.

[Frits Overmars]

... either the NSR250 road bike or the NSR125 had it flowing below the EX port but the racers didn't.......The later RS125 NX4 though has the plug in the front i guess left over from Machining or might hint at road bike or multi use origins of the moulds.
340617
The cylinder on the left is not from an RS125 NX4 but from an NF4 that was still strongly based on the CR125 MX-engine, with a hose feed from the pump to the side of the cylinder.
Its successor, the NX4 cylinder, got its water from below, under the exhaust, through internal channels cast in the crankcases, as did all subsequent Honda racers.

I'm still trying to get used to you guys talking about Honda NSR street models. I don't think we ever got any NSR street bikes over here. To me, NSR is the designation for a 250cc or 500cc Honda works racer (there never was an NSR125, only A-kits for a few selected riders and B-kits for riders with more money than talent).
The Honda production racers were called RS.
The cooling channel through the exhaust bridge was exclusively reserved for the late-model NSR cylinders.

[katinas]

340617
The cylinder on the left is not from an RS125 NX4 but from an early-model NF4 that was still strongly based on the CR125 MX-engine, with a hose feed from the pump to the side of the cylinder.


Interesting, on CR 125 mx cylinders, Honda used coolant intake over C transfer over very long period ( and first RS125/250 ND roadracers ), from first 1980 water cooled type to 2004.
On "Final Cut" cylinders from 2005 to 2007 they used under the exhaust flow from crankcase.

[katinas]

Here is pic of partial solution for the TM cylinder.
Cold water is squirted back over the transfer tops, with only small holes under the Exhaust duct cooling that with flow direct from the case below.

On TM 125 MX 2010 engines they use all flow over exhaust ( like on RGV 250 ). Later they used cylinders with all flow under exhaust .

Very interesting, when cooling intake and outlet is on opposite sides how to spread the flow, how much through cylinder and how much through head.

[yatasaki]

Setting the ratio litlle longer and using the tow of a faster rider might be a good strategy too but I think this depends on the speed you are racing at. In my case top speed is little over 80 kph.
In my story I'm more garelli rider:cool:
For that reason I was calculating all possible final ratios ,36 of them, then pick sprocket which would be universal for the rear wheel as it is much harder to change. My question is, (and partly answered by Frits some years ago on this thread) to choose between acceleration from corners AND acceleration to max speed and where max speed point should be .
In some cases you need crucial intermediate gear (let's say between 3rd and 4th) and to adjust that you have to change your final ratio in expense not using final gear 5th or 6th at all.
In your case Pavel I would go for huge 100cc kart overrev

[husaberg]

340617
The cylinder on the left is not from an RS125 NX4 but from an early-model NF4 that was still strongly based on the CR125 MX-engine, with a hose feed from the pump to the side of the cylinder.
Later NF4 cylinders got their water from below, under the exhaust, through internal channels cast in the crankcases, as did all subsequent Honda racers,
including of course the RS125 NX4.

I'm still trying to get used to you guys talking about Honda NSR street models. I don't think we ever got any NSR street bikes over here. To me, NSR is the designation for a 250cc or 500cc Honda works racer (there never was an NSR125, only A-kits for a few selected riders and B-kits for riders with more money than talent).
The Honda production racers were called RS.
The cooling channel through the exhaust bridge was exclusively reserved for the late-model NSR cylinders.

You are correct i just went through and had a look 87,88,89,90, all as per you description the opposite to the CR125 ftrom what it was based on. As detailed from Katinas a few posts ago.
I missed that in my attempt to make sense of it.
Maybe as i said Honda just used the shortest hose to save money and they thought the RS feed was just better
it seems the side feed bung was just a left over from using the same castings. so it would seem late NF$ they made the change to the crankcases but not the Cylinder design. likely again to save money.

When i am talking re road NSR125 they are generally JC22 or JC20, i can't say if they had them in Holland but they did in Europe they also had the CRM125 which had the same engine.
i think They actually made the NSR125's in Italy. for Europe
https://en.wikipedia.org/wiki/Honda_NSR125
looking at this the Netherlands is one of the few countries in Europe who never got the NSR125
https://www.cmsnl.com/honda-nsr125_model1222/

Road NSR MC16,18,21 mc28 (pro arm) these were sold in Europe mostly i think as Grey Imports, no idea who got official imports
These were available with F3 kits for racing and quite a few came factory with Dry a clutch SP models etc etc.
Here is all the models quick details http://www.tso.us.com/parts-book/honda/0250nsr250/id-model/2-index/model-id.asp
https://en.wikipedia.org/wiki/Honda_NSR250R

NZ never got the NSR125 and 150 other than as Grey imports
But we gotthe NSR250 extensively as official and used imports

The first model RS250 Production racer shared design with the NSR250 MC road bikes and many parts gearbox inc swap over.
Later RS250's and NSR250 Racers are different and have the chain on the other side

the NSR road bikes are all Crankcase reed designs and have a RC valve std
I think pretty much any NSR road bike will accept a RS cylinder of some sort, or the late PV Cr125 cylinder

Katinas has a NS250 which i think was MC14 which is more like a 2 cylinder NS400.
They had the in fashion Atac Valve over square bore and stroke.
NS250 and NS400 are cylinder reed designs but Honda cylinder reed Cr125 Cylinders bolt on.
NZ and Aussie were keen on the 250 as we had 250cc learner laws here. plus 250 proddy racing was very popular
Mick Doohan raised to prominence was on a proddy 250 two years later he was on NSR500
Matt from Tyger can correct the stuff i got wrong

[F5 Dave]

Think he'd start with his company name :innocent:

[husaberg]

Think he'd start with his company name :innocent:
http://tyga-performance.com/index.php?osCsid=97tdu0uaekkrqilg4v9m51fb87
I would agree if he spelt it English in the first place.

Awe shucks I had nearly all the letters though . I was at least 45% right.
I am not so sure i even spelt Matt right either now.
Just so we are clear TYGA TYGA TYGA is the company Name.
Purveyors of fine looking Bodywork and Exhausts and many other parts for Exotic sports bikes. Such as the NSR NC and CBR's plus RGV etc etc etc.
Although i also called Katinas a Japanese Sword. or a gay looking Suzuki twice in that post.:psst:

https://www.youtube.com/watch?v=VurBc_QpUbs

[katinas]

Yes Husa, CR 125 cylinders from 1983 to 1986 bolt on NS 250/400 case. NS 250 coded MC 11 and NS 400 NC 19.
I have all CR 125 reed cylinders from 1980 to 1986 and they differs every year. From 1985 they stick to 54mm stroke, but trans and ex windows height on 85 86 cylinders left the same like on previous 50,6mm stroke types. just cylinder was higher.
1980 1981 cylinder had huge transfers port and windows, maybe left from air cooled 1979 cylinder.
But very interesting to see how they changed cooling around EX port on these cylinders. Every year more and more cooling around EX and on 1986 cylinder they let water flow little under EX. In 1987 Honda stick to case reed engine on CR 125.

As about NS engines, both 250/400 with 50.6mm stroke crank, but there is so much differences everywhere.
NS 250 crank same as first RS 250 ND5 1984 1986 racers, crank web dia. 86mm ( on NS 400 93mm), big end 22mm ( NS400 24mm ) and both with same conrod length 109mm. Carbs on 250 28mm, 400 26mm. Ignition CDI on 250 simply goes with huge retarded after 10500rpm, on 400 no restriction.
Cylinders ( bore 250 - 56mm, 400-57mm but 400 for South Africa version 56mm) looks same from outside, but castings in cooling zone differs ( cylinder wall thick on 250-7.5mm on 400-10.5mm. And primary gears are very wide on 400.
All indications on NS 400 shows that maybe Honda engineers started 3 cylinder street project with 500 cc in they minds. But maybe after some tests found too much warm from engine, and decide lower capacity, but this is just guess.

First street NSR 250 MC 16 cylinders had much narrower EX windows than later MC18 21 28, but biggest change on later mC21 28 was bigger and heavier crank with thicker stronger conrods ( mc16 18 96mm dia. big end 24mm, MC21 28 100mm dia big end 25 mm.) F3 crank for mc16 18 goes with stronger RS 250 NF conrods.
And one interesting thing on crankcases - the space between crank web and crankcase upper wall that left for mix flow on front cylinder, on MC21 28 much smaller than on MC 16 18. And not because of the bigger crank web, but castings lower. More flow between crank webs.

[F5 Dave]

Think they just decided that Japan was dominating market and with 400cc barrier that's what they'd sell most of. Suzuki did 400 and 500cc versions. Seemingly Yamaha though a 400cc, 500cc replica was just not a 500, but must have questioned their logic when the others made 400s.

[katinas]

Think they just decided that Japan was dominating market and with 400cc barrier that's what they'd sell most of. Suzuki did 400 and 500cc versions. Seemingly Yamaha though a 400cc, 500cc replica was just not a 500, but must have questioned their logic when the others made 400s.

So for 400cc NS engine had huge material reserve everywhere.

I want to ask you about your project pistons again. As cylinders on your engine is with Boyesen are you tried Wiseco pistons with holes or without.
Thanks.

[husaberg]

Think they just decided that Japan was dominating market and with 400cc barrier that's what they'd sell most of. Suzuki did 400 and 500cc versions. Seemingly Yamaha though a 400cc, 500cc replica was just not a 500, but must have questioned their logic when the others made 400s.

I think Katinas might be onto it with the cooking model rather than full monty 500.
The never released the Fireblade for 2 years as they were worried about lawsuits.
Another reason might be how much trouble the MVX250 gave and how much the NS500 and RS500 vibrated.
i am not really sure how the NS400 is balanced i don't think its like the MVX with the heavy piston and rod in the upper center.
either way Making it a 400 meant it never had to directly compete with the full 500's

[F5 Dave]

So for 400cc NS engine had huge material reserve everywhere.

I want to ask you about your project pistons again. As cylinders on your engine is with Boyesen are you tried Wiseco pistons with holes or without.
Thanks.
Sorry I have no idea what you are asking. My current project is a CPI kit 496 RZ, nothing experimental just kit bits.

[katinas]

340617
Honda works racer (there never was an NSR125, only A-kits for a few selected riders and B-kits for riders with more money than talent).
The Honda production racers were called RS.


I have one cylinder from RS 125 that differs from others. Seller said that this cylinder was used in WGP race, but I didnt know anything more.
All ports looks best that I ever see, but one thing is very interesting. Looks like they added some material to normal production cylinder from C side for bigger B ports.
But I cant understand how they do that, additional casting form or welding on. Add photo

[katinas]

Sorry I have no idea what you are asking. My current project is a CPI kit 496 RZ, nothing experimental just kit bits.

Yes this is about CPI cylinder block pistons. Just interested are pistons inlet skirt with two windows like on most pistons with reed on cylinder configuration.

[F5 Dave]

Ahh. Yes as many holes as you can poke a stick at.

[wobbly]

Just a short note to Frits re the KZ class engines.
We have a blind on rails down each side of the main radiator , and with this in place the red warning light for 40*C comes on after about two racing laps so cooling on the grid isnt an issue.
Also if you rev a KZ on the stand there is a slight discernible vibration in the chassis ( pedals ) under 6000 rpm.
Above that level ( racing rpm ) there are no vibes to speak of at all.
At the 58 % balance factor most of these engines have - a balance shaft violates KISS for no reason ( or Occams Razor as I learnt just recently ).

[katinas]

Ahh. Yes as many holes as you can poke a stick at.
Thanks Dave,
As original Honda NS cylinder intake route is very similar to CPI, just Boyesen arranged downward more blocked from B, so I interested how piston looks like.

[katinas]

I think Katinas might be onto it with the cooking model rather than full monty 500.
The never released the Fireblade for 2 years as they were worried about lawsuits.
Another reason might be how much trouble the MVX250 gave and how much the NS500 and RS500 vibrated.
i am not really sure how the NS400 is balanced i don't think its like the MVX with the heavy piston and rod in the upper center.
either way Making it a 400 meant it never had to directly compete with the full 500's

On NS400 all three crankpins is in one line, so vertical piston work alone, after 90 degrees two horizontal cylinders fired. Just center cylinder crank webs heavier.
Engine is on the rubber, stroke 50.6mm, angle V90, so I think this help eliminate vibrations. Both NS 250 and 400 didnt have any troubles with this.

NS500 and RS500 racers V 112 angle engine, separately 120 degrees firing, 54mm stroke and no silent blocks, so maybe more difficult eliminate vibrations . And double power output.

DRM guys made 500 kits for NS, with two EX ports and dry clutch
https://page.auctions.yahoo.co.jp/jp/auction/g298854497

[husaberg]

On NS400 all three crankpins is in one line, so vertical piston work alone, after 90 degrees two horizontal cylinders fired.
Engine is on the rubber, stroke 50.6mm, angle V90, so I think this help eliminate vibrations. Both NS 250 and 400 no troubles with vibration.

NS500 and RS500 racers V 112 angle engine, separately 120 degrees firing, 54mm stroke and no silent blocks. And double power output.

DRM guys made 500 kits for NS, with two EX ports and dry clutch
https://page.auctions.yahoo.co.jp/jp/auction/g298854497

The MVX250 is also 90 degree two down one up. but the top gudgeon is real big and solid to equal the weight of the other two lower cylinders.
The NS500 also had a balance shaft. With it firing at 120 ntervals it had uneven spacing because of the bigger V i posted some stuff on the RS500 and RS500 eons ago.
The NSR25, NS250, MVX250 and NS400 are all big bang then.

[katinas]

Very interesting about MVX balance
Thanks

[husaberg]

Very interesting about MVX balance
Thanks

it wasnt without it problems ut when it ran it was smooth but i are not entirely sure some of the issues they had with reliability were not related to its very odd set up. not all 250s were thrashed so the rliability issues might be overstated
But it had if i rember right iron cylinders not just the liners

i will find the links
340667340668340669
The story goes early ones had a 13mm or so solid pin that was later replaved by a 17mm hollow one or similar.
Some here
https://www.kiwibiker.co.nz/forums/album.php?albumid=5017

https://www.kiwibiker.co.nz/forums/album.php?albumid=4861

[husaberg]

Wouldn't fit
340674340675340676340677340678

[katinas]

it wasnt without it problems it was smooth but i are not entierely sure some of the issues they had were not related to its very odd set up.

i will find the links
340667340668340669

Some here
https://www.kiwibiker.co.nz/forums/album.php?albumid=5017

WOW....
Yes I know that this is bad thing, but always interesting how factories trying to resolve some problems.

Maybe not in theme, but I still thinking why Suzuki on second generation RGV 250 VJ22 used sooo heavy steel lover triple clamp and heavy front brake disc steel inner part. First idea that this is cheaper (or opposite), but maybe they want more loads on front, or eliminate some high frequency frame vibrations that emerged after all work was done.

[Matt@TYGA]

Matt from Tyger can correct the stuff i got wrong

I'll see if I can add a little....

I have on my knee an NSR250 MC21 and NSR150SP cylinder.

The NSR150SP coolant enters the cylinder under the exhuast duct and flows around to the top of the exhaust duct, then back over the transfers. The head gasket will allow coolant into the head on it's journey, with the biggest passages through the gasket being at the rear of the cylinder. The coolant then exits at the front side of the head.

The 250 cylinder is very similar, however, the coolant enters under the exhaust duct and then flows up and over the transfers. There is a small area above the exhaust duct, but it looks like it'll cool the recess for the exhaust valve, rather than any relevant cooling of the duct. Similar story to the 150SP regarding the head gasket and flow inside the head.

Extra cooling of the exhaust duct would be somewhat easier on the 150SP, as the cooling channels are already there, just needs a little work. Looks to me like something could be done by coming in from the end of the duct (where the manifold would bolt on). Maybe drill some holes, or mill some slots, allowing the coolant to flow right to the end of the duct. The manifold could then be used with some sealant, to keep things from leaking.

Not quite so simple on the 250 cylinder, as there's no meat on top of the duct. But I guess one could weld a plate over this, closing it in, and then using this for cooling. Worth a thought perhaps.

Cheers,

Matt.

[Frits Overmars]

I have one cylinder from RS 125 that differs from others. Seller said that this cylinder was used in WGP race, but I didnt know anything more. All ports looks best that I ever see, but one thing is very interesting. Looks like they added some material to normal production cylinder from C side for bigger B ports. But I cant understand how they do that, additional casting form or welding on.Early Honda RS125 cylinders had a tendency of cracking at the stud mounts, so the first Honda A-kits contained sand-cast cylinders with higher ears.
Several standard NF4 cylinders were modified in the same way by welding, but it is quite possible that your pictures show a genuine early A-kit cylinder.
Later A-kit cylinders were recognizable by their exhaust power valve, something that the standard RS125 never had.
340684

[Pavel Myslik]

In my story I'm more garelli rider:cool:
For that reason I was calculating all possible final ratios ,36 of them, then pick sprocket which would be universal for the rear wheel as it is much harder to change. My question is, (and partly answered by Frits some years ago on this thread) to choose between acceleration from corners AND acceleration to max speed and where max speed point should be .
In some cases you need crucial intermediate gear (let's say between 3rd and 4th) and to adjust that you have to change your final ratio in expense not using final gear 5th or 6th at all.
In your case Pavel I would go for huge 100cc kart overrev

Yes, I always go for the overrev and change the sprockets all the time. I have modified the sprocket mounting system to change them easier.
I don't know which gearbox you use but usually the difference in ratios is smaller with higher gears so maybe you should try using all gears, then if you have to compensate for the "intermediate gear" the trade off will be smaller. Or try to change your line on the track.
I have been told always have the engine overreved at or slightly before the fastest point of the track. It is also more benevolent to rider's error than gearing faster.
But if you are really good, capable of slipstreaming and then passing on the brakes...
If you are interested here is one of my races and if you are not then pardon my narcissism. :innocent: : https://www.youtube.com/watch?v=bk7glKx236c&t=43s
Skip to 12:20, the last laps were interesting.

[wobbly]

Anyone got a TZR250 2MA cylinder - reedblock - manifold I could have a look at.

[Pursang]

Plenty of work has already been done on this with no good results.
Firstly Jan filled in under the Ex duct to reduce the coolant flow - result deto city.
Secondly, I ceramic coated the duct inside surface , result lost power - deto city.
Third,Franco at TM tried the air gap shell idea, result - deto city.
Fourth,TM originally designed the KZ10 with all the coolant flow entering the cylinder under the duct.
This heats up ALL the water ,including that flowing over the transfer tops.
They later plugged the holes and directed all the water into the cylinder , from the side over the top of the duct.
This gave better power.
Lastly I bored a hole into the water jacket above the boost port , so all the cold water flowed over the transfers first.
Then added two 3mm holes thru the plugs under the Ex duct to help cool this area separately.
Result just over 1 Hp in 48 , with alot less deto level when under full power.
But the CIK and NZ techo guys would not allow this " additional " water circuit.
Moral of the ( long ) story is that cooling the duct first is bad , as is not cooling it at all , as you must keep the retained
mixture in front of the piston as cool as is possible to prevent the returning stuffing wave from pushing hot gas back into the cylinder.

Here is a highly efficient insulation that does not retain heat in its body or on the surface.


https://youtu.be/aqR4_UoBIzY

Not sure how long it would last in an exhaust duct, might need to fit a new one for each 'heat'.

cheers, Daryl.

[F5 Dave]

Anyone got a TZR250 2MA cylinder - reedblock - manifold I could have a look at.
I should have the reed and manifold but no cylinder of 1KT which should be the same as 2MA (but totally different to 3MA). UK and probably Europe got 2MA, Japs and us got 1KT

[yatasaki]

Pavel, you have pretty tight ratios for three speed moped, I thought it would be much wider. That green rider's bike is slowing down from lap to lap but he has much less mistakes than you..
Glad to see good moped race.
This is how Slovenians prepare 60cc tomos six speed engne, my friends bike,just love to hear this bike singing from time to time
https://youtu.be/XrjUK2431pk

[katinas]

Early Honda RS125 cylinders had a tendency of cracking at the stud mounts, so the first Honda A-kits contained sand-cast cylinders with higher ears.
Several standard NF4 cylinders were modified in the same way by welding, but it is quite possible that your pictures show a genuine early A-kit cylinder.
Later A-kit cylinders were recognizable by their exhaust power valve, something that the standard RS125 never had.
34Thank yo0684

Thank you Frits, very helpful and interesting how they do things.

I will try to follow with what I have about RS cylinders studs location location at C, with some guess.

First crankcase reed RS 125/250 NF4/5 stud ears height at C side was just 15.5mm, at EX side 20.5mm.
Dimension between studs at EX side 96mm, at C side 80mm ( like on the first NSR500 1984 and 1985 86 with vertical reed block position, maybe because all cylinders exhaust arranged same side and wider studs location at C would be in the way of rear cylinders exhaust manifolds )
Between Ex and C side studs pairs 81mm and looks that this is not changed until the end..

When NX series appears 1995, Honda widened studs location at C on 1998 or 2000 (not sure) 125 NX4 from 80mm to 94mm for more more open space between horizontal reed block and transfers ports ( like on the 1987 NSR 500 new 112 degree engine where exhaust pairs on different sides and left more room for horizontal reed block position with wider studs location and more open directly to transfers ports). Stud ears height at C was rised from 15.5mm to 20.5mm ( like on new NX 250 ) like at EX side.

First RS 250 NX5 appears in 1993, but as both exhaust on the same side, new V 75 angle and cylinders close to each other, no space for wider studs location at C, because of exhaust, so studs position they left unchanged 80mm. But vertical reed block position had no conflict with this. And this configuration left until last 250 season. Just Daijiro special engine, with exhaust on different sides and horizontal reed blocks position, must used special cylinders with wider studs location at C maybe from 500.

I have std RS 125 NX cylinder from 1996 engine and one interesting thing. The B port wall shape near C, changed gradually from lower to upper corner lines. Add drawing. Cylinder not ported.
And add another interesting cylinder, maybe like you write, for NX 125 with power valve, modified (welding everywhere with wider 94mm stud location at C) from nx 250 , I think from All Japan Championship.

[2T Institute]

NF4 never had water under the exhaust, from the factory (had right angled press in inlet) . The cases can be modified to send the water up under the exhaust duct.

[Frits Overmars]

NF4 never had water under the exhaust, from the factory (had right angled press in inlet) . The cases can be modified to send the water up under the exhaust duct.You're quite right; I corrected my post. Below is a standard NF4 engine.
When taking a (too) quick glance through my Honda-stuff, I noticed an NF4 with water from below, but now it turns out to be the modified engine from Dutchman Hans Spaan, one of the very few riders deemed worthy of a Honda A-kit.
Honda used to have the mechanics of those riders come to Japan in order to assemble their bikes under HRC supervision. When Spaan turned up, he was assumed to be such a mechanic. The Honda-people were astonished that he could not only ride fast enough to be vice-world champion, but that he could also work with his hands.
340692

[Michael Moore]

When Spaan turned up, he was assumed to be such a mechanic and the Honda-people were astonished that he could not only ride fast enough to be vice-world champion, but that he could also work with his hands.

Similar to when Sammy Miller was picked up by Honda and at a test ride at the factory rode it a bit and came back and took a hacksaw and modified the frame so it would steer better. The story goes that all the high brass onlookers were horrified/amazed.

[lodgernz]

Pavel, you have pretty tight ratios for three speed moped, I thought it would be much wider. That green rider's bike is slowing down from lap to lap but he has much less mistakes than you..
Glad to see good moped race.
This is how Slovenians prepare 60cc tomos six speed engne, my friends bike,just love to hear this bike singing from time to time
https://youtu.be/XrjUK2431pk

Wow! What a great street race. Fastest bike in that race by a good margin. Any tech details of the engine?

[Michael Moore]

I was recently looking at some information on the Athena GET ECU for the Flettner, excuse me, KTM TPI 2T singles. :) I was surprised to see that in the "Race Kit" they relocate the injectors:


https://transmoto.com.au/product-get-new-2t-ecu-injector-kit/

GET has also released an “ECULMB Race Kit”, which includes the ECULMB control unit and an injector support kit for KTM’s 250/300EXC TPI and Husqvarna’s TE250/300i.

Interestingly, instead of using KTM’s patented TPI technology (where fuel is injected into the barrel’s transfer ports via two injectors, rather than directly into the combustion chamber), the ECULMB Race Kit’s injectors are positioned between the cylinder and the throttle body – a change that, according to GET, helps bolster power across the rev range, but especially at low and medium RPMs to improve rideability.

TPI makes so much sense, I'm having difficulty figuring out why moving the injectors to a more traditional location would give improved power/rideability. Does anyone have an idea on that?

thanks,
Michael

[yatasaki]

Black graph is bike on 2:35 with no.81 tomos 5 gear 60cc cast iron cylinder with dellorto 24
Red graph. 6 gear Tomos 60cc cast iron cylinder,piston ported dellorto 26 bike which was recording. Tuned by same guy.
You can see me as well on 2:35 with no.42, pity, I was leading the race, but piece of clutch ended in gear selector, 3rd at the end but with no clutch problems would be very hard to keep up with bike recording . Very sleazy street track

[husaberg]

I was recently looking at some information on the Athena GET ECU for the Flettner, excuse me, KTM TPI 2T singles. :) I was surprised to see that in the "Race Kit" they relocate the injectors:



TPI makes so much sense, I'm having difficulty figuring out why moving the injectors to a more traditional location would give improved power/rideability. Does anyone have an idea on that?

thanks,
Michael

I have a theory. But not sure i have a clue
Honda pursued Fi for power (with the hope of better economy to boot) as did Cagiva they both ended up with Port or throttle body injection.
Both hoped it may have lead to a more compact engine carbs take up more room between the V and cagiva thought it might have allowed the use of disc valves later on.
340708340709340710340711
Di was also banned in 500 Gps i think anyway
Honda had already tried some sort of Cylinder or crankcase transfer port injection in the 70s on the RC125's but it was crap then( likely mechanical. )I have this from two sources one of them was someone who had to ride it.
340706
You can be pretty confident before they settled on the NSR500 and EXP system they tried hundreds of different ideas but their main aim was power with better economy.
Honda also raced a 250 in the 250 japanese champs for a few years prior to Itos season on the NSR500
Here is the first ever pic i have found of its engine set up. Its called the RS250RW
340707 heres the std one https://blogimg.goo.ne.jp/user_image/54/09/c37114e3fb864117a5292b05dfea357c.jpg
Evitrude and orbitial etc went for emissions and economy etc and ended up DI.
Flettner went for what he could get to work and and decent performance driveabilty.
ktm tried them all, But they were after emissions with the same power they couldn't get DI to make decent power so they just copied fletner.;)

[katinas]

Thanks for advice Katinas. Easy to follow it! I making big parts for pistons need order correct material like AA2018 AA2218 AA2618
Or may be for CNC mill without forging there is better materials...



Long time ago, for pistons we used heat resistant AK-4 alloy ( used in jet engines with Fe and Ni ) very similar to 2618, but of course you must know.
Now I tested only 2618 T6, just what I can get. Made from peace, without forging and after run in, pistons works fine. There is 2618A, but little different composition and little more expansion, but more resist to cracking.
From castings alloys, I remember low expansion AL-26, maybe very similar to 4032, but more fragile than 2618. Of course now days maybe exist better special alloys.

Just remember, long time ago I prepared IZ Planeta Sport 340 for road racing (add photo of original and modified for race ). We got some aftermarket cast pistons made from old bus diesels engines pistons, with much silicon ( from my memory it was from Ikarus bus ). They never seized, even with zero clearance on friends engine ( he must put piston with force to cylinder when assemble and I cant believed that he use this engine without any seize). The best things about this original motorcycle, was that frame was made from CrMo like front fork tubes and upper triple clamp with fork lower legs made from B-95 alloy similar to 7075.

But once, with my race modified version, on the straight, when engine revs up little longer at nearly 10000 rpm (with 76 bore and 75mm stoke) all ended with catastrophe bang. I didnt release what was first, conrod or piston, but conrod flying out of the engine and I left with aluminium- silicon sand in my handful.

Honda, for some GP two stroke pistons, used casting AC8A-T6 alloy with max Si 13 %, Ni 1.5 % and Cu 1.3%. https://patents.google.com/patent/DE60208944T2/en

[katinas]

Honda also raced a 250 in the 250 japanese champs for a few years prior to Itos season on the NSR500
Here is the first ever pic i have found of its engine set up. Its called the RS250RW
340707

Thanks Husa, indeed first ever...

[jbiplane]

Long time ago, for pistons we used heat resistant AK-4 alloy ( used in jet engines with Fe and Ni ) very similar to 2618, but of course you must know.



Honda, for some GP two stroke pistons, used casting AC8A-T6 alloy with max Si 13 %, Ni 1.5 % and Cu 1.3%. https://patents.google.com/patent/DE60208944T2/en

Thanks for so detailed answer. Will educate all stuff you sent :)

[Pursang]

Play-doh seems a bit childish & impractical :baby:
Here is a commercial product that might allow the exhaust gasses to pass right through the duct into the chamber, without leaving behind a lot of heat to warm the fresh charge.


https://youtu.be/VzMbBxJccI8

Unlike a Tin or Ceramic coffee cup, the carbon foam replicates the thermos flask:
Reflective/emissive contact surface, long heat paths and minimal conduction and convection.

And if it all seems a bit too "Space Age" remember that V-2 rockets were using graphite vanes in the exhaust nozzle, way back in 1944.
Aircraft & F1 have been using carbon brakes for around 50 years.

Cheers, Daryl.

[Pursang]

In 1994 Lockheed did some successful development and testing work for NASA on Carbon Carbon Composite pistons.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940031440.pdf

Biggest problem they found was that the air cooled cylinders expanded more than the pistons did.
This opens the opportunity for CCC cylinders, some work has been done on these.
Carbon Carbon matrix has also been used to provide for highly efficient liquid cooling of computer chips.

Once again that was pretty much rocket science back then. Highly specialised and incredibly expensive.
Now we can design & fabricate n-dimensional fibre matrix patterns to achieve whatever physical properties are required for an application.

Items can be molded, printed and/or machined. There are dozens of US & Chinese companies touting on-line for the fabrication work.

cheers, Daryl.

[katinas]

If I remember correctly, CC pistons was used on RC models engines, but some chipping at the top edge, limited using them.

[Pavel Myslik]

Pavel, you have pretty tight ratios for three speed moped, I thought it would be much wider. That green rider's bike is slowing down from lap to lap but he has much less mistakes than you..
Glad to see good moped race.
This is how Slovenians prepare 60cc tomos six speed engne, my friends bike,just love to hear this bike singing from time to time
https://youtu.be/XrjUK2431pk

The gearbox is not original. Fortunately one guy in my country makes these for very reasonable price. The green rider has more experience and even I am able to be faster than him sometimes, he is more consistent and has excelent starts. This was the second race of the day and I managed to beat him in the first so it was a tie. :)
Hats off to your friend, It's really singing nicely.

[guyhockley]

I see the Ryger has moved to the next, logical phase of its development...

https://youtu.be/6M9Yqctk_Tg

http://www.ridders.nu/Webpaginas/pagina_drukgestuurde_tweetakt/druktweetakt_frameset.htm

[F5 Dave]

I thought when the video started i thought it would be some fancy coffee machine.

70hp coffee anyone? Where do I send money to invest?

[Pursang]

Here is a nice overview article from 1994.
https://www.thefreelibrary.com/Engine makers tap carbon-carbon pistons.-a015497837

NASA still has patents over most of this stuff, from around 20 years ago
Perhaps when they lapse, there might be some more progress.

cheers, Daryl

[wobbly]

Now that might be achievable - 30,000 rpm 70Hp coffee machine .
Be a go on Kickstarter for sure.

[yatasaki]

Would be nice to see colour of deto-combustion

[F5 Dave]

Somewhere in the Emerald isles Paddy is working on a Whiskey augmented version.
72.5hp at a reduced 28790 rpm.

[Michael Moore]

Is there a performance reason why 2T exhaust port manifolds generally are placed at an angle to the cylinder axis instead of perpendicular to it? On 4T generally the closer the alignment of the port to the valve stem the better.

I can see the angled manifolds making it easier to get the pipes attached and out of the way/pointed the direction they need to go, and maybe it creates more room above the manifold to fit an exhaust power valve. But if those issues are ignored is there any reason for the angle -- better flow in/out of the port for either escaping exhaust or for reflected waves in the exhaust pushing unburnt mixture back into the cylinder, etc?

I'm not asking about the transition from the port shape to the round exhaust pipe manifold shape, just the angle.

thanks,
Michael

[wax]

Im sorry to bring this up again and yes i have searched for the answer on here and while i can find some information I cant find enough to satisfy me or to make me understand.
Its re the exhaust port actually not going all the way to bdc.
I understand that the exhaust port has done all its or most of its work by the time the transfers open and so its not really doing much. But whats the advantage of not having it go all the way to the bottom. The only thing i am thinking is by keeping it smaller it keeps the velocity up ?

[husaberg]

Is there a performance reason why 2T exhaust port manifolds generally are placed at an angle to the cylinder axis instead of perpendicular to it? On 4T generally the closer the alignment of the port to the valve stem the better.

I can see the angled manifolds making it easier to get the pipes attached and out of the way/pointed the direction they need to go, and maybe it creates more room above the manifold to fit an exhaust power valve. But if those issues are ignored is there any reason for the angle -- better flow in/out of the port for either escaping exhaust or for reflected waves in the exhaust pushing unburnt mixture back into the cylinder, etc?

I'm not asking about the transition from the port shape to the round exhaust pipe manifold shape, just the angle.

thanks,
Michael

Frits and Jan will give a better explanation but as i understand it 25 Degrees downwards exit works best.


The exhaust port isn't canted downward 30°. The flange mounting face is canted downward 30° but the roof of the exhaust duct exits the cylinder at 25°.
The reason is that this angle gives the best flow.



Frits can give a detailed explanation but i suspect it simply due to the fact thats what direction it expanding out to anyway and to make it 90 Degess to the bore would make it change direction

[Michael Moore]

Thanks, I was thinking the downward angle might help control things with the exhaust first starting to exit at the top of the port/roof of the duct, so that makes some sense to me. I hoped that everyone was doing it that way for a reason, not just for "because". :)

cheers,
Michael

[katinas]

Im sorry to bring this up again and yes i have searched for the answer on here and while i can find some information I cant find enough to satisfy me or to make me understand.
Its re the exhaust port actually not going all the way to bdc.
I understand that the exhaust port has done all its or most of its work by the time the transfers open and so its not really doing much. But whats the advantage of not having it go all the way to the bottom. The only thing i am thinking is by keeping it smaller it keeps the velocity up ?

Maybe, would be very nice that bottom part of exhaust port moving down together with the piston top edge, so exhaust gases flow without step and without sudden pressure and energy drop behind the piston in the first phase of exhaust opening at the beginning of ex port.
But as this is impossible, so little higher exhaust window bottom and port bottom first part, maybe can help reduce, too much pressure drop and at the same time restricts some fresh gas from flow to exhaust port. But as two stroke is holistic process, the balance most important. (Add photo of Honda engine exhaust port bottom part shape typical for they racers).

Some time ago, cant remember correctly, about 1987 1990, two Institutes, one in Tallinn Estonia, worked on mathematical model for two stroke engine process and they ended with integral model that mismatched to real world about 5%, except very hardly calculated, at that time, process in the whole exhaust system, at the phase, when exhaust window is closed.
Estonians was always very keen about road racing, riders was always very fast, as they tuned engines.
https://www.youtube.com/watch?v=7HTNxEAJDO8&t=19s

[Michael Moore]

Here's a link to that HOnda patent document

https://patentimages.storage.googleapis.com/fa/7d/5a/a38e65d10a1928/US6129059.pdf

[F5 Dave]

Now That is a Fabulous photo katinas ;)

[TZ350]

Im sorry to bring this up again and yes i have searched for the answer on here and while i can find some information I cant find enough to satisfy me or to make me understand. Its re the exhaust port actually not going all the way to bdc. I understand that the exhaust port has done all its or most of its work by the time the transfers open and so its not really doing much. But whats the advantage of not having it go all the way to the bottom. The only thing i am thinking is by keeping it smaller it keeps the velocity up ?

Yes. That is my understanding too, that keeping the velocity up and reduced short circuiting is the benefit. Radiusing the leading edge also showed a benefit.

[Haufen]

Im sorry to bring this up again and yes i have searched for the answer on here and while i can find some information I cant find enough to satisfy me or to make me understand.
Its re the exhaust port actually not going all the way to bdc.
I understand that the exhaust port has done all its or most of its work by the time the transfers open and so its not really doing much. But whats the advantage of not having it go all the way to the bottom. The only thing i am thinking is by keeping it smaller it keeps the velocity up ?

Think of it like this:

Not having the exhaust port go to BDC belongs to the category of not having the port be the maximum area possible all the way from exhaust port opens to BDC. Let me try an explanation chain:

Why don't you have an exhaust port of the maximum width (area) all the way to BDC? Easy, because at some point the exhaust port will be too big and power will suffer.
Additionally, blowdown area before the transfers open is most important. So when most of the exhaust flow has already happened by the blowdown, where would you put the rest of the exhaust port area?
How would you shape the port? Well, you'd shape it so that it would be most useful, wouldn't you. And how would it be most useful?
By preventing short circuiting in the best possible way.

So if you know the behaviour of the scavenging column and the area where it reaches the exhaust side of the cylinder wall, you can adjust your exhaust port shape accordingly. On the engine I developed I had access to huge CFD capacities simulating the scavenging behaviour under various conditions. When the exhaust port shape had been adjusted accordingly, the engine had more power and less emissions. Unfortunately, most of us don't have CFD simulations of their engines, I know. As a first start, for modern transfer ports like in karts or GP road racing, I'd start with a V-shape of the exhaust, extending to BDC, but very narrow in that area and only increase width there when the area above has been maxed out.

[wobbly]

" understand that the exhaust port has done all its or most of its work by the time the transfers open and so its not really doing much. But whats the advantage of not having it go all the way to the bottom "

You are only thinking about this in a narrow field of view.
First is Blowdown , that we all know is very critical.
Angling the duct downward helps to reduce the eddies/ turbulence created by the flow exiting the just opened piston/port area , and the reduced area ( x Cosine of the down angle ) keeps the velocity profile higher.
This then increases the diffuser efficiency.

But then at BDC the pipe does most of its " work " ,this is when the depression created by the exiting wave does the job of pulling residual Ex gases out of the cylinder .
And a by product of this is that when the cylinder is over scavenged, we get clean air/fuel sitting in the duct - that then subsequently gets pushed back past the closing piston /port area.
Lifting the floor above BDC and filling in the bottom corner rads , not only reduces the duct area , but also help reduce short circuiting from the A port directly.

Thus we have two vital elements at odds with each other - overscavenging to get clean mixture in the duct Vs short circuiting ruining the scavenging pattern ( Frits leaning tower ) within the cylinder.
Getting the two optimized is still where " black art " is present in this time of computerized everything.

[wax]

Ok right got you i think. Cheers wobbly.
I have read the leaning tower of transfer enough times i can nearly recite it. Awesome piece of work.

So I get the exhaust coming heading down the duct towards the diffuser and over scavenging. Having the exhaust port floor higher than bdc then would in effect create a wall to stop the A ports heading straight out the exhaust. That makes sense. These things get more and more and more complicated the more i learn.
I need to put this engine im doing into enginemod and see what it comes back with for me

Thanks

[Frits Overmars]

Ok right got you i think. Cheers wobbly. I have read the leaning tower of transfer enough times i can nearly recite it. Awesome piece of work....
Having the exhaust port floor higher than bdc then would in effect create a wall to stop the A ports heading straight out the exhaust. That's right Wax.
Having the lower part of the exhaust window narrower or non-existent makes it less inviting for the mixture flow coming from the A-ports to turn right into the exhaust. Having the exhaust duct floor higher reduces turbulence in the outgoing exhaust flow during the blowdown phase and it reduces the exhaust duct cross-section,
so the volume of washed-through fresh charge is contained in a longer column, with less contact area with the hot spent gases.
And some time after BDC, that exhaust port puts on a different hat: it becomes a transfer port. The raised exhaust floor guides the fresh charge over the piston top edge, so there is less turbulence here as well. And finally the smaller exhaust window leaves more surface for the piston to lean against, improving load distribution.

[jbiplane]

Simple question
What is correct and optimal gap (clearance) axial and radial crankshaft to crankcase?
How it correlate with rpm? Any study on this?

[Frits Overmars]

What is correct and optimal gap (clearance) axial and radial crankshaft to crankcase? How it correlate with rpm? Any study on this?About 1 mm clearance, both axial and radial, in order to avoid viscous losses.
As the crankshaft should also have some axial play (0,4 mm for a 125 cc engine), this must be taken into account.
I am not aware of any published studies about the subject, only experimental experience.

[jbiplane]

About 1 mm clearance, both axial and radial, in order to avoid viscous losses.
As the crankshaft should also have some axial play (0,4 mm for a 125 cc engine), this must be taken into account.
I am not aware of any published studies about the subject, only experimental experience.

Thanks Frits, I use 1.5mm before. Will try make a bit less :)

[jbiplane]

Estimating correct ways to take system ECU of engine with reservation.

What should be happen in case of improbable, but possible breakdown of the IGBT transistor for ignition or injection.
IGBT of the ignition coil... Brains will heated and burn down. And the pilot will not notice this in time.

Permanently open injector will overflow cylinder and could result hydro shock before pilot manages switch manually to reserve circuit of injection.
I.e. operation of IGBT transistors should be under control by some algorithms.

Exists MC33812 for one channel ingition and injection https://www.nxp.com/docs/en/fact-sheet/MC33812FS.pdf
and MC33814 for two channels / cylinders. Exist simple Found Evolution board for MC33814.
http://cache.freescale.com/files/analog/doc/user_guide/KT33814UG.pdf

Seems use of MC33814 - is a fast way to make the "protected" brains.

Seems AVR industrial + CAN hardware and ISO1050 for a CAN interface should do the job by the best way.

[Frits Overmars]

Thanks Frits, I use 1.5mm before. Will try make a bit less :)Leave it, Valery. 1 mm is just the minimum value. 1,5 mm will be fine.

[peewee]

when installing flywheel on the crankshaft does anyone put grease or oil on the taper ? it never happen to me but i seen people get a seized flywheel

[Frits Overmars]

when installing flywheel on the crankshaft does anyone put grease or oil on the taper ? it never happen to me but i seen people get a seized flywheelNever. On the contrary, I'd wipe it clean with a petrol rag. But then I also omit the key, if any.

[yatasaki]

Putting oil or grease will make a kind of micro hydrolocks on cone surfaces (anyone seen SKF cone coupling will know what I'm talking) and cone would not be self locking any more. Keys are mostly there for positioning and partly for torque/power transmission.
It is the cone that will spread power/torque around circumference of the shaft.

[breezy]

Never. On the contrary, I'd wipe it clean with a petrol rag. But then I also omit the key, if any.

Frits, would you concur that the advise you give would be relevent to the work you helped with the aprilia engine only and that there could actually be other ways of improving engine power. have you been seen or experienced alternative methods? and if so would you expand on such improvements?........

[wobbly]

Having the ignition taper clean and dry , and omitting the key , works perfectly on an Aprilia and a BSA Bantam.
The key is only needed for radial positioning,the taper has sufficient grip to prevent any slip if done properly.
If that is the question you are asking

[peewee]

Putting oil or grease will make a kind of micro hydrolocks on cone surfaces (anyone seen SKF cone coupling will know what I'm talking) and cone would not be self locking any more. Keys are mostly there for positioning and partly for torque/power transmission.
It is the cone that will spread power/torque around circumference of the shaft.

that makes sense. oil and grease may create a thin layer and prevent the tapers from fully seating. flywheel seizing on the taper might be from corosion of the steels

[F5 Dave]

But boy the key saves time.

[TZ350]

But boy the key saves time.

and tears of frustration, bad language and totally ruined race days ........ :facepalm: .... I just love those little keys that make sure you get the timing right on re assembly, especially when you are in a hurry.

[husaberg]

Having the ignition taper clean and dry , and omitting the key , works perfectly on an Aprilia and a BSA Bantam.
The key is only needed for radial positioning,the taper has sufficient grip to prevent any slip if done properly.
If that is the question you are asking

Thats there is something that caused myself endless frustration until i finally sought sage advice from an elder and simp;ly relaped a Mag taper.
If you ever have any issus at all the bloody taper on. You can check with bearing blue but a fine grinding paste will show up any high spots anyway.
i was making stronger keys loctite and all sorts of stupid shit, when quite simply the key was the key is nor for the lock by only the location.



But boy the key saves time.


and tears of frustration, bad language and totally ruined race days ........ :facepalm: .... I just love those little keys that make sure you get the timing right on re assembly, especially when you are in a hurry.

A few shitty old pommy bikes don't have the keys to make up for it you get to do the nut up with a Hammer.
https://villiersservices.co.uk/bmz_cache/c/c21f17212fc5a295458347fa7a12f729.image.640x480.jpg
Many of the old bikes also used tapers for the Crankpins inc manx Nortons
And stupid Harleys
https://i.ebayimg.com/thumbs/images/g/c00AAOSwXepcSi6E/s-l225.jpg

[F5 Dave]

I've moved stuff off key and regretted it having to replicate work. Ignitech makes it so easy to adjust from a known point. Getting back to known is a drag.

[katinas]

with a Hammer.

There is other, 100% guaranty way to remove flywheel, if nothing helps. Tried this once in young days, but think first and last time.

What ever I did, could not remove big flywheel magneto ( 165 mm dia.) from my first project bike with outboard engine (found old pic).
Then simply spin engine to 5000 rpm and flywheel easy moves up, falls on garage wooden floor and was standing without any movement. Only after some seconds I release that this piece not only simply standing, but rotated 5000 rpm at the same time . Only after 10 seconds this monster begun slowly move to the inside of the garage. It was time to do something, I quickly close garage door and the war began...........
When the Peace come after sooooo long time, inside of my friends garage was unrecognizable. It was absolutely colorful, mostly black from old used oil that he was kept in glass bottles. Other colors was from paints cans. All tools, rags, trash, was everywhere, but the bike was not damaged only black.
What was happen if the bike was arranged to outside way in the garage.....
I did not use this flywheel any more, just remember, made total loss ignition with points and battery, later cdi with small rotor.

[_____]

I found out the most important thing for any propper cone connection is to bore the end of the hub cylindric to the end-diameter of the cone plus 0.1mm.

This makes the flywheel suit on the crankshaft like a glove. (or what ever conical shaft-hub connection we are talkin about)
Very fine valve grinding paste is also a good idea, but only if something is very off.

Cheers Chris

[Matt@TYGA]

Also concur on the dry taper for the flywheel.
Made a handful of flywheels for things, with and without key grooves (just hand filed) which were just for a rough guide when fitting.
As long as the taper is a good fit and the correct taper of course then the key does nothing more than help locate.
My ancient Chinese mini lathe in the shed does a reasonable job of cutting internal tapers, but some lapping with fine paste is usually required

[Frits Overmars]

No doubt a key can be helpful in fitting a flywheel in the correct position. My practice of omitting it stems from experience with moped engines that were older than me,
when I was 15 years old.
When trying to build one running engine out of three non-running ones, the male and female tapers did not always match 100% (99,9% is not good enough).
So, in the usual twice-a-week seizure, the flywheel would rotate on the shaft and the key would destroy the tapers.

A second reason for omitting the key is that sometimes you want to set the ignition beyond its built-in limits. And if you can't move the stator far enough, you need to move the rotor beyond what the key would allow. Today we can set the timing wherever we want with a couple of keyboard clicks; in those days we had barely left flintstone ignition.

The third reason: when I started working on the first Rotax 250cc tandem-twins in 1980, I noticed that the crankshaft seals ran on the hubs of the coupling gears,
and air could creep in through the key grooves in the hubs, causing a couple of nasty seizures. That didn't improve my sympathy for keys.


Frits, would you concur that the advise you give would be relevent to the work you helped with the aprilia engine only and that there could actually be other ways of improving engine power. have you been seen or experienced alternative methods? and if so would you expand on such improvements?........I assume that you're not referring to the advise regarding the tapers, as that wouldn't improve power.
I've worked with two-stroke engines for 55 years now, so my advise is not based on Aprilia experience only, though I learned a lot from Jan Thiel, almost as much as from my own countless mistakes. By the way, Jan and I go back way beyond Aprilia; we got together at Bultaco, Minarelli and Garelli, to name a few successful brands.

I have seen a lot of alternative methods, one even more daft than the other, like corrugated crankshafts that should act as ventilators (they would, if they would rotate ten times as fast), golf ball dimpling all over the place, and 'flame channels' in combustion chambers, that greatly improved detonation, as did thermal barriers on chambers and piston domes.
The alternative methods that do work, like supercharging and nitro, are forbidden in most branches of motorsport. With one exception: E85 is considered a regular fuel and it is permitted in many branches of motorsport. It works better than some expensive racing fuels... But don't spread the word.

[yatasaki]

on[/I] the hubs of the coupling gears,
and air could creep in through the key grooves in the hubs, causing a couple of nasty seizures. That didn't improve my sympathy for keys.


Especially when the shaft is non-conical, you have to soak key in silicone to seal.
For each tomos manual gearbox this is a must.

[breezy]

No doubt a key can be helpful in fitting a flywheel in the correct position. My practice of omitting it stems from experience with moped engines that were older than me,
when I was 15 years old.
When trying to build one running engine out of three non-running ones, the male and female tapers did not always match 100% (99,9% is not good enough).
So, in the usual twice-a-week seizure, the flywheel would rotate on the shaft and the key would destroy the tapers.

A second reason for omitting the key is that sometimes you want to set the ignition beyond its built-in limits. And if you can't move the stator far enough, you need to move the rotor beyond what the key would allow. Today we can set the timing wherever we want with a couple of keyboard clicks; in those days we had barely left flintstone ignition.

The third reason: when I started working on the first Rotax 250cc tandem-twins in 1980, I noticed that the crankshaft seals ran on the hubs of the coupling gears,
and air could creep in through the key grooves in the hubs, causing a couple of nasty seizures. That didn't improve my sympathy for keys.

I assume that you're not referring to the advise regarding the tapers, as that wouldn't improve power.
I've worked with two-stroke engines for 55 years now, so my advise is not based on Aprilia experience only, though I learned a lot from Jan Thiel, almost as much as from my own countless mistakes. By the way, Jan and I go back way beyond Aprilia; we got together at Bultaco, Minarelli and Garelli, to name a few successful brands.

I have seen a lot of alternative methods, one even more daft than the other, like corrugated crankshafts that should act as ventilators (they would, if they would rotate ten times as fast), golf ball dimpling all over the place, and 'flame channels' in combustion chambers, that greatly improved detonation, as did thermal barriers on chambers and piston domes.
The alternative methods that do work, like supercharging and nitro, are forbidden in most branches of motorsport. With one exception: E85 is considered a regular fuel and it is permitted in many branches of motorsport. It works better than some expensive racing fuels... But don't spread the word.

Yes your right Frits, not tapers:laugh: thanks for reply:niceone: Have you been able to do any more with regard to your multi port central scavenging concept?

[Frits Overmars]

Have you been able to do any more with regard to your multi port central scavenging concept?At the moment it's proving that my exhaust duct ideas work. Despite the mild 190° exhaust timing, the pipe pulses are the strongest I've ever experienced.
Which is great, except that the torque dip at 2/3 of max.torque rpm is also the worst I've ever seen. We're working on that now, other activities permitting.

[ken seeber]

Ignition advice wanted. A friend has an approx Honda 1990 CR250 engine on his superkart and the ignition CDI is cooked. Is there an alternative (aftermarket etc) to just getting a new Honda part item, which apparently are rare and/or expensive.

Any help would be appreciated....gotta keep the competition alive..

[F5 Dave]

Here's one prepared earlier.


https://www.bikeside.de/IGNITECH_1

I bought a few of these, meant for CR (they put them together in kits, mine just happened to be for CR250 but I didn't use the curve supplied on the disc) but used on my RZ, a TF, MB, GP etc.

Or email them, if can't find the kit, they speak English.

Or buy locally and I'll mail you the curve.


Actually I used CR250 stator and Rectifier Regulator/ Capacitor on a couple of my race bikes. They drive an Ignitech easily.

[peewee]

Ignition advice wanted. A friend has an approx Honda 1990 CR250 engine on his superkart and the ignition CDI is cooked. Is there an alternative (aftermarket etc) to just getting a new Honda part item, which apparently are rare and/or expensive.

Any help would be appreciated....gotta keep the competition alive..

theres a few on usa ebay right now for 150usd. im sure theyll ship worldwide. maybe he could use cr125 box if the connector is the same. theres probly alot of 250 aftermarket stuff but it may cost more. vortex is one aftermarket option but its 550usd.

[husaberg]

Ignition advice wanted. A friend has an approx Honda 1990 CR250 engine on his superkart and the ignition CDI is cooked. Is there an alternative (aftermarket etc) to just getting a new Honda part item, which apparently are rare and/or expensive.

Any help would be appreciated....gotta keep the competition alive..


Here's one prepared earlier.


https://www.bikeside.de/IGNITECH_1

I bought a few of these, meant for CR (they put them together in kits, mine just happened to be for CR250 but I didn't use the curve supplied on the disc) but used on my RZ, a TF, MB, GP etc.

Or email them, if can't find the kit, they speak English.

Or buy locally and I'll mail you the curve.


Actually I used CR250 stator and Rectifier Regulator/ Capacitor on a couple of my race bikes. They drive an Ignitech easily.


The 1990-1996 Cr125 shared the same staor as the CR250 89-92
Dave used a post 98 Stator as did Speedpro not sure re the years think there was a 6 pole and 8 pole with differing outputs but from memory less than 10-25 watts.
They have a real small flywheel same size as CR80. 78mm or so.
I think the KTM kokusan set up is the same setup the bits might be more useful in the future as the Honda parts become scarce.
Husky and others also used the same ignition with different backplates
http://www.cafehusky.com/threads/08-cr125-with-ktm-125-lighting-stator-howd-ya-do-that.2755/
these style stators are cheap moose racing etc
https://www.rmstator.com/en_ww/products/high-output-stator-for-ktm-exc-mxc-sx-sxs-xc-xc-w-125-144-150-200-250-300-360-380-1997-2016-rm01374

[Michael Moore]

Ken, Jeff Henise has been using the hpi.be ignitions on the F37, CT1, YCS1, customer Honda 160/175 twins, etc and seems to be doing well with them.

cheers,
Michael

[F5 Dave]

Hpi is quite expensive. Ignitech is the biz.

[F5 Dave]

I'm using $10 Chinese rec/regs and 2200uf caps these days if not already fitted. If not already sorted let me know and I'll sort you out.

[katinas]

At the moment it's proving that my exhaust duct ideas work. Despite the mild 190° exhaust timing, the pipe pulses are the strongest I've ever experienced.
Which is great, except that the torque dip at 2/3 of max.torque rpm is also the worst I've ever seen. We're working on that now, other activities permitting.

Frits, very interesting and glad to hear about your work results. Thanks.

Maybe this is not help, but simply one interesting idea about flow direction from transfers with two EX on opposite sides.

[husaberg]

At the moment it's proving that my exhaust duct ideas work. Despite the mild 190° exhaust timing, the pipe pulses are the strongest I've ever experienced.
Which is great, except that the torque dip at 2/3 of max.torque rpm is also the worst I've ever seen. We're working on that now, other activities permitting.

Is that resonance if you arre getting the stongest pipe pulse wont you also get the strongest interrupting wave also? or is it not at the right rev scale to be this.
I tried to find a 4T pic to map it out. also not sure if i am using correct term but its the dips you see on a power curve that repeat themselves at regular intervals

[lodgernz]

The difference is that the 40mm Lectron has a 36mm venturi behind the slide.
Thus at 1/2 throttle it acts like a 36mm carb, at WOT it acts like a 40mm carb.
The area change is even greater in a 30mm body as they use in 50cc racing.
At 1/2 throttle it has a 26mm venturi,giving 33% more velocity /fuel signal than a parallel bored 30mm carb.

Wobbly, I'm curious about the venturi behind the slide in the Lectron carbs.
Is it a smaller diameter, so the entire throat is reduced, or is it offset so it is only in the lower part of the throat?

[SwePatrick]

A question(or some questions)

As i have found out that my bike loves the heat in my dyno when i have forgotten to switch on the coolingfan,, yes i has happenened ;)
And everytime when i forgot i set a dynorecord for my engine, it runs on 97% methanol and 3% Shell Advance Racing M oil.

So i drew this paralell, as i have studied methanol needs 64,7degree of heat to boil(or convert to steam) and petrol is variable depending on pressure(boil/steam point, i dunno the correct word).
I figured why not help it get there more quickly as it is a dragrace engine for short distance(1/8mile)
I need my power early in the race.
I have also found that when this happens it needs even more fuel, does it set the oxygen in the fuel free at above boilingpoint?
I can add more fuel with my powerjet when this happens and gain 3-4hp.

So why bother with this?
The engine revs ~13500rpm and make peak power at 13200rpm, this make me think there is very little time to make the fuel convert to 'steam'.

So i came up with this design:
http://forumbilder.se/I4F6I/ribs.jpg

As you can see i have deleted the waterpassages above the camber, but have added surface area next to the squish, to make this somewhat cooled in a small way.

Is there by any chance this will work?

Rgds.
Patrick

[Frits Overmars]

Is that resonance if you arre getting the stongest pipe pulse wont you also get the strongest interrupting wave also? or is it not at the right rev scale to be this. I tried to find a 4T pic to map it out. also not sure if i am using correct term but its the dips you see on a power curve that repeat themselves at regular intervalsI'm not sure if I understand what you're saying Husa, so I'll just write my own eludication.

If the initial pulse entering an exhaust pipe is stronger, so will be all other pulses in the pipe, that is correct. Foul-strokes can show a number of power curve ripples along the rpm scale, usually caused by higher harmonics in their inlet and exhaust systems. But on a pipe-dependent two-stroke there is one big 'dip' at 2/3 of max.torque rpm, caused by the returning pipe pulses arriving back at the cylinder before the appropriate ports are closed by the piston.
The stuffing pulse arrives when the transfers are still open, pushing the fresh cylinder contents back into the crankcase. Next, that stuffing pulse is reflected at the open exhaust port as a suction pulse that sucks whatever mixture was left in the cylinder, out of it, so there will be hardly anything left to ignite. This causes the torque dip at 2/3 of max.torque rpm. And since my cylinder produces beautifully strong initial pulses, the torque dip looks like an abyss.

Of course we tried the usual remedies. There are no exhaust power valves because they would mess up my beautiful exhaust ducts and ditto cooling system.
Water injection or trombone pipes would probably work, but that would be too much effort for now. Besides, it would violate my KISS-principle.
Raising the compression ratio might help a bit but I don't want to make modifications that can't be permanent (the present low comression ratio will be an important factor in achieving power).

Advancing the ignition timing to well before TDC leads to an early onset of combustion and a high expansion rate between the end of combustion and the beginning of exhaust opening. Therefore the spent gases will be cooler when they exit the cylinder, and they'll carry less energy with which they could create chaos.
But in our case even 35° ignition advance wasn't enough to solve the problem. Which makes me think that it's not only the pulses that create a mess, but also the gas flow itself, moving to and fro with a Helmholtz frequency that has the same effect as those too-early pulses.

Next step: cutting the end cones completely off and see what that does to the dip. When we start the engine, you might be able to hear it down under...
If that works, we'll try to recreate proper expansion pipes, using my variable end cone exit.

[husaberg]

I'm not sure if I understand what you're saying Husa, so I'll just write my own eludication.
If the initial pulse entering an exhaust pipe is stronger, so will be all other pulses in the pipe, that is correct. Foul-strokes can show a number of power curve ripples along the rpm scale, usually caused by higher harmonics in their inlet and exhaust systems. But on a pipe-dependent two-stroke there is one big 'dip' at 2/3 of max.torque rpm, caused by the returning pipe pulses arriving back at the cylinder before the appropriate ports are closed by the piston. The stuffing pulse arrives when the transfers are still open, pushing the fresh cylinder contents back into the crankcase. Next, that stuffing pulse is reflected at the open exhaust port as a suction pulse that sucks whatever mixture was left in the cylinder, out of it, so there will be hardly anything left to ignite. This causes the torque dip at 2/3 of max.torque rpm. And since my cylinder produces a beautifully strong initial pulse, the torque dip looks like an abyss.

Of course we tried the usual remedies. There are no exhaust power valves because they would mess up my beautiful exhaust ducts and ditto cooling system.
Water injection or trombone pipes would probably work, but that would be too much effort for now. Besides, it would violate my KISS-principle.
Raising the compression ratio might help a bit but I don't want to make modifications that can't be permanent (the present low comression ratio will be an important factor in achieving power).
Advancing the ignition timing to well before TDC leads to an early onset of combustion and a high expansion rate between the end of combustion and the beginning of exhaust opening. Therefore the spent gases will be cooler when they exit the cylinder, and they'll carry less energy with which they could create chaos.
But in our case even 35° ignition advance wasn't enough to solve the problem. Which makes me think that it's not only the pulses that create a mess, but also the gas flow itself, moving to and fro with a Helmholtz frequency that has the same effect as those too-early pulses.
Next step: cutting the end cones completely off and see what that does to the dip. When we start the engine, you might be able to hear it down under...
Thanks for the explanation.
Atac chamber is in keeping with KISS
Farmaken did a nice one

[Frits Overmars]

Thanks for the explanation. Atac chamber is in keeping with KISSYes, more or less, and we seriously thought about it, I'll give you that. But it too would mess up my exhaust ducts.

[husaberg]

Yes, more or less, and we seriously thought about it, I'll give you that. But it too would mess up my exhaust ducts.
mount it further back

So this is where I am up to so far, Butterfly valve seems to be a long way from the header ID so plan B is to make up a spool valve like a Yamaha power valve and fit it in the same place as the collar which is currently on the header so that the OD of the spool is flush with the header ID when closed .:blink:
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Hi TZ, ran the ATAC this weekend - hard to know how much difference it makes but does seem to work :cool:


Cows are dry, that means more time in the shed

Here is the latest version ; using a jaycar frequency counter/switch to drive a R1 servo motor to operate the spool valve on the header pipe

Using a DPDT switch mounted on the servo to reverse the motor - unless someone can point me at an electronic limit/polarity switch to make use of the servo`s in built potentiometer ??

[Frits Overmars]

mount it further backThanks Husa, I'd just started looking for 'Farmaken'. I'll keep it in mind.

[husaberg]

Thanks Husa, I'd just started looking for 'Farmaken'. I'll keep it in mind.

closer would be better, but the spool valve can go close,closer, than a butterfly, hondas atacs were never that close anyway its only an idea to see if it can be tuned out without running manx norton style megaphones. or should that be 50's DKW's

[Frits Overmars]

...it's only an idea to see if it can be tuned out without running manx norton style megaphones. or should that be 50's DKW'sIt must have been before your time, or you wouldn't ask Husa. A Norton Manx would have been blown off its stand by a DKW.
During the 1998 Centennial TT I was in the pit lane, at least 20 meter behind a DKW. The pulses coming from its megaphones hit me in the chest, taking my breath away. And you could hear it go all around the circuit, no matter how much other traffic there was.
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[Michael Moore]

I recall reading an IoM article in Motorcycle Sport magazine, late 1960s/early 1970s, where for some reason the racer put megaphones on his Yamaha 2T twin. I think there was some surprise that they apparently worked OK, for certain values of "OK".

[karter444]

Hi Wobbly
can i presume that all other things being equal a barrel with the aux exhaust port passages ground out wider all the way into the exhaust manifold will produce more power than one that hasnt been extended
cheers Richard

[Haufen]

I'm not sure if I understand what you're saying Husa, so I'll just write my own eludication.

If the initial pulse entering an exhaust pipe is stronger, so will be all other pulses in the pipe, that is correct. Foul-strokes can show a number of power curve ripples along the rpm scale, usually caused by higher harmonics in their inlet and exhaust systems. But on a pipe-dependent two-stroke there is one big 'dip' at 2/3 of max.torque rpm, caused by the returning pipe pulses arriving back at the cylinder before the appropriate ports are closed by the piston.
The stuffing pulse arrives when the transfers are still open, pushing the fresh cylinder contents back into the crankcase. Next, that stuffing pulse is reflected at the open exhaust port as a suction pulse that sucks whatever mixture was left in the cylinder, out of it, so there will be hardly anything left to ignite. This causes the torque dip at 2/3 of max.torque rpm. And since my cylinder produces beautifully strong initial pulses, the torque dip looks like an abyss.

Of course we tried the usual remedies. There are no exhaust power valves because they would mess up my beautiful exhaust ducts and ditto cooling system.
Water injection or trombone pipes would probably work, but that would be too much effort for now. Besides, it would violate my KISS-principle.
Raising the compression ratio might help a bit but I don't want to make modifications that can't be permanent (the present low comression ratio will be an important factor in achieving power).

Advancing the ignition timing to well before TDC leads to an early onset of combustion and a high expansion rate between the end of combustion and the beginning of exhaust opening. Therefore the spent gases will be cooler when they exit the cylinder, and they'll carry less energy with which they could create chaos.
But in our case even 35° ignition advance wasn't enough to solve the problem. Which makes me think that it's not only the pulses that create a mess, but also the gas flow itself, moving to and fro with a Helmholtz frequency that has the same effect as those too-early pulses.

Next step: cutting the end cones completely off and see what that does to the dip. When we start the engine, you might be able to hear it down under...
If that works, we'll try to recreate proper expansion pipes, using my variable end cone exit.


If your engine is not able to overcome the torque dip alone, why not help it a bit? Rev it into the current max. rpm, then shift a gear or two down and see what it is capable of when in the powerband. Another way would be to use the clutch. Quickly done, and helps with finding the reason for its behaviour, too (besides the smile the result might put on your face).

[guyhockley]

Frits, would it be worth trying perforated end cones a la 100cc kart pipes before cutting them off completely?

[wobbly]

Guy, its surprising how well the perf rear cone works.Varying the diameter and spacing of the holes you can shape the power curve dramatically.
Along with the main body diameter/length/volume over the rear cone.

Richard - that is a reasonable assumption to make - but the issue is that the duct exit is too big anyways.
Thus adding ears down the side produces the exact effect you are after , but this is almost exactly offset by the now even bigger area duct.
But if one was to fill the roof and or floor and CNC the correct shape and exit area then that would be an entirely different matter.
Wouldnt have a clue how to do that at all now would I.

[DoldGuy]

Wouldnt have a clue how to do that at all now would I.


No, not at all...

[peewee]

Hi Wobbly
can i presume that all other things being equal a barrel with the aux exhaust port passages ground out wider all the way into the exhaust manifold will produce more power than one that hasnt been extended
cheers Richard

not to far back it seems like i might of posted some of how i did this for my yam twin, if not i could show how i did it. from engmod i knew the effective area at bore face and from there i figured the area i need at spigot exit , also the area halfway to exit, with the passage length being 2x bore. from there i figure how tall the ears would be and how wide the passage. this told me how much i needed to weld up the floor and how much to weld down the sides in order to create the wings. what helped me alot was i drew a 2d model on 5mm x 5mm graph paper

[husaberg]

Anyone able to translate Japanglish
I was thinking this was about the Honda Bridged port with eyebrows porting deviation that yamaha made around that time?
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[Frits Overmars]

Frits, would it be worth trying perforated end cones a la 100cc kart pipes before cutting them off completely?Great minds think alike, Guy :p. This is how we tried to kill that nasty return pulse. The result (lack of) made me conclude that it wasn't just the pulse that messed things up; it had to be the Helmholtz resonance as well, so more drastic measures were called for. We'll turn those pipes into foulstroke megaphones; that'll teach 'm!
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[speedpro]

The ones I have seen for karts have a perforated cone within the rear cone

[_____]

This is how we tried to kill that nasty return pulse.


Wobbly as well as Jan have stated here, that (having three exhaust ports) rising the auxilaries to the level of the main exhaust creates a power curve with about one HP more but way less powerband. I know from simulation experience as well as dyno work: this is true in oil&fuel as well as in bits&bites.

The Aprilia RSA has enough blowdown with about 199°.
Please teach me: why does your engine with roughly twice as much specific exhaust time area should need only a fraction of lower exhaust opening duration AND a straight exhaust timing edge?
What kind of scavenging scheme did you apply in the engine simulation?

Cheers, the curious
Chris

[guyhockley]

Michael Moore was looking for help identifying a hub centre steering set up. I had a couple of pictures that looked similar and one of them does seem to have helped. The other picture was from a Swiss hill climb, can't find much at all about it except a thread on an Australian forum! Thought TZ350 might find it amusing as the bike is using 6 injectors (on a twin...)

https://www.forum.motorcyclenews.bike/threads/sre-250-efi-seiler.22836/

[guyhockley]

PS. Dunger? Same as "old nail" or heap?

[Frits Overmars]

The Aprilia RSA has enough blowdown with about 199°. Please teach me:
why does your engine with roughly twice as much specific exhaust time area should need only a fraction of lower exhaust opening duration AND a straight exhaust timing edge?
What kind of scavenging scheme did you apply in the engine simulation?Chris, I think teaching should start with defining the correct terminology, so that we all know what I'm on about.
Let's start with a port in a cylinder. That port has a certain area.
We put that cylinder on a crankcase containing a crankshaft with a certain stroke and a certain conrod/stroke-ratio.
Turning the crankshaft will give a certain angle.area for the port in the cylinder. So we can say that a port in a cylinder on an engine has a certain angle.area.
Adding rpm will assign a certain time to that angle which gives us a time.area value. So a port in a cylinder on a running engine has a certain time.area.
And finally dividing that TA value by the cylinder capacity, including the combustion volume (which everybody keeps forgetting) will give the specific time.area, which is an indication of how well an engine can breathe and at what rpm it will run out of breath.
In theory every engine needs the same specific time.area. If one engine has more specific angle.area than another, we can rev it higher, so at the end of the day they will both have the same specific time.area.

My engine does not have roughly twice as much specific exhaust time.area. In fact it has infinite time.area as it's not running right now and with the ports permanently open, the sum total of open area multiplied by open time is infinite.
We need to talk about angle.area instead. But my engine does not have much of that, because the exhaust floor is well above the transfer ceilings, so the total area of the exhaust ports is not that big.
Now let's talk about blowdown angle.area. That it has; quite a lot, because with all of the exhaust port area situated above the transfers, all of it serves as blowdown area. There is so much blowdown area that I can afford to keep the timing low (for a competition engine) at 190°.
By the way, where did you get the idea that my exhaust ports have straight timing edges? They don't, as you can see below, because the piston ring wouldn't like it.
My engine simulation was fed with the applicable transfer layout: six radially aimed transfers, each with a 25° axial angle.
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[TZ350]

Michael The other picture was from a Swiss hill climb, can't find much at all about it except a thread on an Australian forum! Thought TZ350 might find it amusing as the bike is using 6 injectors (on a twin...)

https://www.forum.motorcyclenews.bike/threads/sre-250-efi-seiler.22836/

That is very interesting. He looks to have successfully done what I am still trying to do. I would love to know more about his setup, if anyone comes across any more info I would love to see it.

Six injectors makes sense for the TZ250.

This is my old EFI air cooled cylinder. For low speed there is a small injector in the middle that is fired on its own and for symmetry two injectors in the B ports doing the same amount of work but in less time at higher rpm.

The two injectors in the B ports are fired together as one logical injector. It is the range of RPM that the injectors have to cover and consequently the reduced time to get things done at the top end that makes two different sizes, a small and then a big injector required. Above about 9,000 rpm this sort of staged injection is required. Both the small and big logical injectors spit about the same amount of fuel per revolution but the big injector only gets a very short amount of time to do it.

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[wobbly]

You have to be careful when looking at the STA numbers for the Aprillia.
From direct measurement it would appear that it has way more transfer STA than Blowdown.
This is not the case in reality as with the big radius on the Exhaust timing edge the effective Cd is increased such that the
flow capability is perfectly matched to that of the transfers , without having to resort to even larger timing numbers.
Having been told by " The Great Leader " here is the new pipe, Jan had to do this to the port design simply to make it work.
If the guy doing the pipe engineering knew what he was doing , this may never have been needed.

[F5 Dave]

Well this is cute. This is a picture of me pushing my finger into the UPP Inlet manifold of my CPI Cheetah through a 50mm tear. There’s a matching one on the other side.
Apparently, this isn’t an isolated incident. Some people will be laughing up their sleeve at my optimism.
I guess I wasn’t looking for it, in a somewhat darkened area, but it explains some carburetion issues.
Have to run the same angle so can’t use CR250 from which the Reedblock is sourced, or straighter shot as carbs just wouldn’t fit the tiny RG250 frame (& would overflow at more angle anyway, they like to as it is).
Chariot seem to do a replacement, but any other ideas? I’m only running the smaller PWK35s.
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[wobbly]

Make an alloy adapter angle block - and use oval Mikuni flange rubbers.
Pleny of examples on Ebay for Banshee.

[F5 Dave]

I've done that before for a couple of the race bikes just doing 2 was putting me off when I'm a billion projects behind and wanted to ride it this summer.
Sorry I'm just getting tired of this thing so I'm in whine mode.

[peewee]

upp stuff is garbage from my experience. genuine mikuni ruuber inlets are top notch. beware of imposter brands

[speedpro]

Mikuni stuff isn't all that expensive either, example and possibly useful: https://www.mikunioz.com/shop/mikuni-flange-45-degree-boot-40mm-spigot-58-75mm-stud-centres/?v=8e3eb2c69a18

[F5 Dave]

It's just licking 100hp, I suppose I could throw 30 away;)

[diesel pig]

Mikuni stuff isn't all that expensive either, example and possibly useful: https://www.mikunioz.com/shop/mikuni-flange-45-degree-boot-40mm-spigot-58-75mm-stud-centres/?v=8e3eb2c69a18

And they are really good to deal with as well.

[guyhockley]

Great minds think alike, Guy :p. This is how we tried to kill that nasty return pulse. The result (lack of) made me conclude that it wasn't just the pulse that messed things up; it had to be the Helmholtz resonance as well, so more drastic measures were called for. We'll turn those pipes into foulstroke megaphones; that'll teach 'm!
340859

Someone always has to go one better...

[Muhr]

Is there anyone who has tips on where to buy new power valve servos with potentiometes

[wobbly]

As a huge number of owners fit aftermarket pipes on the R1 Yamaha , there are plenty of the exup servo motors on Ebay.
All of these are of recent manufacture so they are in good condition compared to the old YPVS units.
The only difference is that the plug is part of the body.
R6 and many other models dont work with the Ignitech.

[Muhr]

Thanks Wob! the only new ones i found are:
https://m.ebay.ie/itm/CAGIVA-MITO-125-FRECCIA-NEW-MOTOR-POWER-VALVE-KOKUSAN-TD-5909-ORIGINAL-JAPAN/291357678436?hash=item43d6455b64:g:18wAAOSw32lYuR1 q

[flyincat]

To the pipe guys....what is the impact of a highly curved pipe in regards to measured length vs reality? In the case of a straight pipe, measured and reality being the same thing. Clearly the inside of the curve is a completely different length than the outside, especially when the fatter section is curved. This must cause the pressure wave to do some funny stuff, no?

What is the proper length measurement method for a highly curved pipe? If the proper way is still the center line, is there a better way than eyeballing the center line?

340966

[Haufen]

To the pipe guys....what is the impact of a highly curved pipe in regards to measured length vs reality? In the case of a straight pipe, measured and reality being the same thing. Clearly the inside of the curve is a completely different length than the outside, especially when the fatter section is curved. This must cause the pressure wave to do some funny stuff, no?

What is the proper length measurement method for a highly curved pipe? If the proper way is still the center line, is there a better way than eyeballing the center line?

340966

Measuring the outside and the inside lengths and dividing the value by two should be more accurate than eyeballing the center line.

I have seen very curved pipes act as if they were a tad shorter compared to the straight versions.

[jamathi]

'sad' news from Holland
RYGER seems to have big financial problems and will probably close down.
Bankruptcy very likely.....
Not very strange after failing to sell even 1 engine in 2 years.....
There is only 50% of the announced 70HP and 30.000 rpm.
And maybe even less!
Earlier claims were a bit exaggerated!
Some people even believed it, I never did....
Knowing from experience the effort it takes to make just 54 HP with a 125cc engine.

I just read on a Dutch forum that RYGER BV has been disbanded....
But Ryger is not bankrupt-yet....

[peewee]

what do you think of this head from 2019 ktm250sx carburetor model ? they used this style in 2014 but i thought they went back to common bathtub design

[Frits Overmars]

'sad' news from Holland. RYGER seems to have big financial problems and will probably close down.
Bankruptcy very likely..... Not very strange after failing to sell even 1 engine in 2 years.....
There is only 50% of the announced 70HP and 30.000 rpm. And maybe even less! Earlier claims were a bit exaggerated!
Some people even believed it, I never did.... Knowing from experience the effort it takes to make just 54 HP with a 125cc engine.
I just read on a Dutch forum that RYGER BV has been disbanded. But Ryger is not bankrupt-yet....This announcement from the Dutch Chamber of Commerce would suggest that they are, Jan:
2019-02-12: Wijziging: Per 15-11-2017 liquidatie beëindigd. Per 11-2-2019 is de rechtspersoon uitgeschreven wegens Geen bekende baten meer aanwezig bij rechtspersoon.I suppose it would also mean that you are no longer bound by your Non-Disclosure Agreement ;) .

[Frits Overmars]

what do you think of this head from 2019 ktm250sx carburetor model ? they used this style in 2014 but i thought they went back to common bathtub designIt would be a bit difficult for KTM to go back to a common bathtub design, as they never did use a bathtub design in the first place.
Below left are a couple of KTM head designs, below right is a bathtub head, looking rather like a bathtub, wouldn't you say? :p
340971 340972

[peewee]

i must have my terms wrong frits. i meen the style with flat roof. what is the reason for no defined squish band ? maybe it has more managable power or something