ESE's works engine tuner

[Condyn]

Our company www.flame-power.com made new REAL TIME engine management units with ARM processor based on Open Sourse RUSEFI.
It so fast that can calculate ammount of fuel and ignition advance angle each RPM for 1...4 cylinder engines

CAPABILITIES

Primary VR or Hall input (configurable with few resistor changes)
Secondary Hall input
x4 analog thermistor (temperature) inputs
x10 analog voltage inputs (0-5v)
x4 high-Z injector outputs
x2 high-current low side outputs for IAC/VVT/other solenoids
Dedicated main relay control output
x4 low-current low side outputs for relays or warning lights
x4 5v logic-level ignition outputs
x2 5v/12v configurable logic level outputs (requires resistor changes)
Electronic throttle body (drive by wire)
CAN connectivity on the plug
USB connectivity on the plug
https://www.homebuiltairplanes.com/forums/attachments/iso-jpg.98807/
https://www.homebuiltairplanes.com/forums/attachments/top-jpg.98808/
Sounds similar to a megasquirt. What control strategies are supported? I’ve been dipping my toes in the world of 2t efi. Currently have mine set up as alpha-n but adding a mass air flow sensor when time permits.

[polcat88]

I have my 3D printer up and running and am continuing on with my snowmobile drag racing cylinder development project. My hope is to design and build a cylinder using the best design features of proven high output engines, notably the Aprilia RSA and Wobbly's further development from there. There are some design parameters that have to be taken into account. My plan right now is to build a 508cc twin with a bore and stroke of 68 X 70mm. If this produces good results an inline four cylinder of 1016cc would follow. I have tentatively chosen a Honda CR250R flat top piston and would move the ring locating pin to the centre of the c port. The 70 mm stroke was chosen because it is stock in a couple of manufacturer variations and allows close to a square engine at the displacements I am interested in. This setup would target max HP at 9500 RPM and due to the use of a CVT belt drive system which will hold the engine at peak power RPM throughout the run requires no overrev power. Snowmobile engines are conventionally inline twin or triple cylinder designs with the intake on the back side of the engine and the exhaust exiting forward. I will be using stock crankcases and crankshafts and this limits the width of the cylinder. In my case the base of the cylinder is approximately 137.5mm wide. I have scaled up and printed an RSA cylinder at a 68 mm bore and unless I have screwed up, which is entirely possible, the base of this cylinder is approximately 173mm wide. Obviously, I do not have the room to include the large sweeping radii of the transfer passages of the Aprilia cylinder. I have attached a couple of pics to hopefully clarify the situation. I can design the exhaust port and ducting and transfer ports themselves inline with Frits' FOS calculations but am concerned that the transfer passages will be a limiting factor. What is the minimum radius that I can get away with? Or am I fighting a losing battle?

[monkeyfumi]

https://www.mahle-powertrain.com/en/experience/mahle-jet-ignition/

Frits, or Wobbly, to your knowledge, has this (or competitors similar systems) ever been trialed in a two-stroke engine? Seems it would bring similar benefits as in a four stroke.

[wobbly]

Polecat - FYI , have a look at the work already done by CPI making cylinders for the TRX250R ( based on CR250 ). http://www.cpindinc.com/pub/view_product/7?lm=2&name=6101-6872-1303
The smallest version has a 72 stroke with 68 bore - this would translate to a 1046cc 4 cylinder.
What they call a long rod is 130mm , but thats bullshit. If you use a CR500 rod at 144 that puts a very different light on things , with a 72mm stroke.

It is alot more beneficial to add stroke than it is to add bore in this case as it is much easyer to construct better duct geometry , plus getting sufficient Blowdown STA ( in a full house tune situation ) with undersquare , is much
easyer than going away from the idealogically correct square bore/stroke - with a bigger overbore.
The only downside is piston speed , but at this time all the MX engines at 250cc use 72 stroke and have proven to be race reliable at 10,000 rpm all day , in kart roadrace scenarios.

The other thing that is a bit of a hobby horse of mine at the moment is to optimize the cooling circuit , especially if it can be done at the design stage..
All the cold water should ( after cooling the case ) enter the cylinder each side of the boost port - travel across the transfers , cool the Ex duct area , then go up into the head.
If this isnt possible , then a single entry above the boost port , directly into the water jacket has the same effect.

[polcat88]

Polecat - FYI , have a look at the work already done by CPI making cylinders for the TRX250R ( based on CR250 ). http://www.cpindinc.com/pub/view_product/7?lm=2&name=6101-6872-1303
The smallest version has a 72 stroke with 68 bore - this would translate to a 1046cc 4 cylinder.
What they call a long rod is 130mm , but thats bullshit. If you use a CR500 rod at 144 that puts a very different light on things , with a 72mm stroke.

It is alot more beneficial to add stroke than it is to add bore in this case as it is much easyer to construct better duct geometry , plus getting sufficient Blowdown STA ( in a full house tune situation ) with undersquare , is much
easyer than going away from the idealogically correct square bore/stroke - with a bigger overbore.
The only downside is piston speed , but at this time all the MX engines at 250cc use 72 stroke and have proven to be race reliable at 10,000 rpm all day , in kart roadrace scenarios.

The other thing that is a bit of a hobby horse of mine at the moment is to optimize the cooling circuit , especially if it can be done at the design stage..
All the cold water should ( after cooling the case ) enter the cylinder each side of the boost port - travel across the transfers , cool the Ex duct area , then go up into the head.
If this isnt possible , then a single entry above the boost port , directly into the water jacket has the same effect.


Thanks for the link Wobbly.I suspect even that cylinder may be too wide. Do you have any idea of verified full race HP numbers for this setup? What size carbs do they use?

[husaberg]

I have my 3D printer up and running and am continuing on with my snowmobile drag racing cylinder development project. My hope is to design and build a cylinder using the best design features of proven high output engines, notably the Aprilia RSA and Wobbly's further development from there. There are some design parameters that have to be taken into account. My plan right now is to build a 508cc twin with a bore and stroke of 68 X 70mm. If this produces good results an inline four cylinder of 1016cc would follow. I have tentatively chosen a Honda CR250R flat top piston and would move the ring locating pin to the centre of the c port. The 70 mm stroke was chosen because it is stock in a couple of manufacturer variations and allows close to a square engine at the displacements I am interested in. This setup would target max HP at 9500 RPM and due to the use of a CVT belt drive system which will hold the engine at peak power RPM throughout the run requires no overrev power. Snowmobile engines are conventionally inline twin or triple cylinder designs with the intake on the back side of the engine and the exhaust exiting forward. I will be using stock crankcases and crankshafts and this limits the width of the cylinder. In my case the base of the cylinder is approximately 137.5mm wide. I have scaled up and printed an RSA cylinder at a 68 mm bore and unless I have screwed up, which is entirely possible, the base of this cylinder is approximately 173mm wide. Obviously, I do not have the room to include the large sweeping radii of the transfer passages of the Aprilia cylinder. I have attached a couple of pics to hopefully clarify the situation. I can design the exhaust port and ducting and transfer ports themselves inline with Frits' FOS calculations but am concerned that the transfer passages will be a limiting factor. What is the minimum radius that I can get away with? Or am I fighting a losing battle?

To get around the width problem make it a v4 or V2. they allow more room for tranfers at a narrower width.
either single or twin crank gives you extra room without excessive width.

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[pete376403]

Seen this?---https://www.cycleworld.com/story/motorcycle-news/kawasaki-to-design-supercharged-two-stroke-hybrid/

[Frits Overmars]

Seen this?---https://www.cycleworld.com/story/motorcycle-news/kawasaki-to-design-supercharged-two-stroke-hybrid/70% efficiency - yeah right. And what about those radical technologies?
A cross-plane crank? Helmut Fath used that in the '70s.
Direct fuel injection? Mercedes did it in the '40s and I wouldn't be surprised if it has been around for about a century.
Overhead inlet and exhaust valves for a two-stroke?
Toyota built a six-in-line DOHC two-stroke with this exact layout, right down to the deflector ridge # 25a between the valves, some 20-odd years ago.
346340
This Kawasaki may become a wonderful machine yet. I just wish that marketing people in general would behave more like responsible historians and less like Donald Trump.
346339

[jbiplane]

Sounds similar to a megasquirt. What control strategies are supported?
All existing fuel strategies are supported. Processor about 10 times more fast than MegaSquirt and it baced on open source project.

[lohring]

346339[/ATTACH]

Our great leader has sent his best general and faithful troopers to quell these outbreaks. May the floss be with you. You'll need it.

Lohring Miller

346341

[Haufen]

70% efficiency - yeah right.

Come on Frits, it's 'experts' that 'believe' that, it must be true! :laugh:

I can imagine such a concept achieving efficiencies in the high fourties, after some development, though. More than double of that of a typical chainsaw engine.

[wobbly]

Polecat - I had CPI make a special Sphynx cylinder with stock bore and stroke = 250cc.
On Avgas this made 68.5 Hp @ 10200 rear wheel on a Dynojet. I would opine that the 68 overbore cylinder on 110 Leaded would easily do 75 and more if using the CR500 rod
as even at 130 the so called "long rod " TRX250 is still way too short.
The Spynx casting has provision for a PV , but with CVT this may not be needed - thinking back to an Aprilia GP though, this made peak power at 13,000 but the PV wasnt fully up till 12,000
thus aiding the front side power all the way up very close to peak.
The gasket width is same as CR250 , I think I have one here , I will have a look.

[ceci]

(Herr Schneurle?) would turn in his grave if he saw that we were still using his system today - he would have moved on!

Although the Schnuerle scavenging is very nostalgically interesting as an iconic 2S model.
The current trend is that of the 3 models in the photo:
https://static-assets.imageservice.cloud/7898476/not-all-two-stroke-engines-are-created-equal-achates.jpg
1st Kawasaki (https://www.cycleworld.com/story/motorcycle-news/kawasaki-to-design-supercharged-two-stroke-hybrid/).
2nd Renault, has spent years researching and developing.
3º This type of motor is the most advanced, is Flettner, its prototype is one of the best solutions for motorcycles

[WilDun]

OOH! this is good!! - I was beginning to think that I was pissing upwind with my beliefs! - now I'm noticing some of my thoughts being vindicated! - maybe it's a bit early for me to be suggesting all these things??

AND yes, I do realize I'll probably never achieve anything myself, but it's great to see all of this stuff coming up - the only way to save the two stroke !! (even if it means using poppets) - but poppets are probably perfectly good for most of the applications mentioned (except OP)! - the good old poppets have managed to survive for a very long time. ......

70%? - I dunno about that!

[ken seeber]

Kawasaki & 70% thermal efficiency.

I've always believed that huge marine externally scavenged 2 stroke diesels were the best in thermal efficiency of around 50%. The main reasons being a very low surface area/volume ratio (= less energy lost to cooling circuit). Supposedly Mercedes claim 50% for their F1 engine, but not sure if this is in conjunction with KERS (or some other regen function). Maybe they had to do it so they could save on fuel costs to be able to pay for Hamilton's totally moderate $72M salary demand.

So, as I understand it, it will:
1. Be comparatively small in capacity = unfavourable surface area/volume ratio
2. Have to drive an external blower = losses need to be accounted for
3. Have friction losses of running camshafts etc at crank speed.

Running at constant speed is in its favour or there is some other bottoming cycle feature that didn't come to light..

Got my doubts. Anyways, it's a wait and see thing. Hope it is true though.

[Flettner]

Isn't this a Toyota thing, didn't I read about this ten years ago?

[WilDun]

I don't think that there are many things today which haven't been tried or at least proposed! - big breakthroughs came in the last century.

As I said before somewhere, it's a matter of fishing them out of the great pool of failures, sifting through them and reassembling them into different configurations, then refining them to suit the times we are in.

All good fun for enthusiasts to try everything, but for manufacturers a very dicey business - the status quo is safer! - good practice to leave the ideas to the enthusiasts, then pick their brains and rob them when the time is right!

[Peter1962]

I don't think that there are many things today which haven't been tried or at least proposed! - big breakthroughs came in the last century.

As I said before somewhere, it's a matter of fishing them out of the great pool of failures, sifting through them and reassembling them into different configurations, then refining them to suit the times we are in.

Alll good fun for enthusiasts to try everything, but for manufacturers a very dicey business - the status quo is safer! - good practice to leave the ideas to the enthusiasts, then pick their brains and rob them when the time is right!


That sounds about like the tentative by KTM to patent Neil's TPI concept...

Good thing that there are open forums on the internet like Kiwibiker, twostrokemotocross.com, deraceheldenvanweleer.nl or pit-lane.biz or thumpertalk.com.

If idea's have been published there, maybe even with working proof of concept, it will be very hard for a manufacturer to take that idea and claim it theirs and file a patent request.

Now, TPI is for everybody.

Same thing with Frits idea of a variable tailpipe. It has been published, there is a timeline as proof. No manufacturer can claim the intellectual property of this concept.

[lohring]

http://strangedevelopment.com/ for more old ideas combined into a new package.

Lohring Miller

[WilDun]

That sounds about like the tentative by KTM to patent Neil's TPI concept...

Good thing that there are open forums on the internet like Kiwibiker, twostrokemotocross.com, deraceheldenvanweleer.nl or pit-lane.biz or thumpertalk.com.

Not really clued up on the details about the laws around it all, but I did know about a couple of small companies who were doing ok selling successful stuff who had to shut down when someone BIG in the world copied their design and called it something else! - Laws are only good against those agree to abide by them! - as they say, "padlocks only stop honest people".

[ken seeber]

http://strangedevelopment.com/ for more old ideas combined into a new package.

Lohring Miller

Lohring, all I could see is lots of nice CNC machining and promises....

[WilDun]

Lohring, all I could see is lots of nice CNC machining and promises....

Yes, same here .... Promising what?

[lohring]

My observations exactly. If you need to improve the simple two stroke's performance, either use a tuned pipe or a turbocharger. Both are well proven and tested solutions. Before that nearly everything you can think of has been tried. See below for a few of the better ideas.

346352

Lohring Miller

[ceci]

My observations exactly. If you need to improve the simple two stroke's performance, either use a tuned pipe or a turbocharger. Both are well proven and tested solutions. Before that nearly everything you can think of has been tried. See below for a few of the better ideas.


Lohring Miller

Which is to improve performance?, get more HP.
And if you did not get more HP but you would avoid hydrocarbon losses. Isn't that improving performance?

[WilDun]

Which is to improve performance?, get more HP.

And if you did not get more HP but you would avoid hydrocarbon losses. Isn't that improving performance?

That is where everything starts to go in different directions! - the racing boys (which this thread is really all about) need as much performance, (ie HP and speed) as is possible, but for the two stroke to get back to universal use by the masses, then a very different type of performance is required - probably much more complicated in order to be used in all sorts of situations!
My belief is that the hybrid type of setup with an engine running within the most efficient rev range but without charging a massive battery pack (as in cars) can fulfill that role much better than trying to get an engine to perform those duties efficiently all over the rev range!

The interest in motorcycle racing is kept alive only by the fact that there are motorcycles on the roads! - racing and everyday use are two entirely different things - (admittedly there are a few dummies who can't see the difference! ):rolleyes:

Lohring , that NACA document was worth reading!

[Pursang]

https://www.mahle-powertrain.com/en/experience/mahle-jet-ignition/

Frits, or Wobbly, to your knowledge, has this (or competitors similar systems) ever been trialed in a two-stroke engine? Seems it would bring similar benefits as in a four stroke.

Hi Monkey, don't know about any 2 stroke use, but has been done before, for four strokes, back in the 1930's, by Packard. I will post what I know in the "Oddball Engines" Thread.
( Forum - Bike mechanics - Engine - Clutch - Transmission - Oddball engines and prototypes )

Cheers, Daryl

[TZ350]

.
NITRO METHANE
.
To days dyno experiments were with my Suzuki RG50 powered Bucket Racer and raw Nitro.

I have always theorized that with a correctly jetted two stroke running properly on race gas or similar one can just squirt raw Nitro Methane into the bell mouth and you will see a power increase with out any air fuel mixture issues. The reason is, that raw Nitro carries just a little more fuel than oxygen so as well as adding oxygen for more power it effectively richens the ingested mixture too.

346359 346358 346357

The experiment was a bit crude. Just squirted the Nitro in. Blue line is Av Gas only and correctly jetted for max power. The red line is with Av Gas and Nitro squirt. The red line shuts of early as it goes over rich. For Nitro to be useful you would need ignition and mixture control. So the conclusion is that with a digital ignition and power jet control Nitro could be a very viable option, pity Nitro is illegal in our racing class.

But anyway if you have ever wondered if Nitro could be a good thing with two strokes then this experiment suggests there are real possibilities there.

[RZ350]

Good to see you never give up Rob.... Well done

[RZ350]

Wobbly, I have a 350RZ motor you built as a <good> road motor for a Napier man in my racebike. A bit down on power but pulls like a school boy.......
I have the top end open for new rings after 3 seasons and a few track days.. ..... Can i contact you regarding the internals of this motor?

cheers Martin

[koenich]

Gents, whats the rule of thumb/experience on piston ring gap? 0,5% of the bore?

346361 346362

Broke this Vertex piston ring (40 mm bore, 0,05 mm bore clearance, 0,15-0,2 mm ring gap, exhaust port chamfered) before 4h of usage...50cc Bidalot.

[F5 Dave]

.
NITRO METHANE
.
To days dyno experiments were with my Suzuki RG50 powered Bucket Racer and raw Nitro.

I have always theorized that with a correctly jetted two stroke running properly on race gas or similar one can just squirt raw Nitro Methane into the bell mouth and you will see a power increase with out any air fuel mixture issues. The reason is, that raw Nitro carries just a little more fuel than oxygen so as well as adding oxygen for more power it effectively richens the ingested mixture too.

346359 346358 346357

The experiment was a bit crude. Just squirted the Nitro in. Blue line is Av Gas only and correctly jetted for max power. The red line is with Av Gas and Nitro squirt. The red line shuts of early as it goes over rich. For Nitro to be useful you would need ignition and mixture control. So the conclusion is that with a digital ignition and power jet control Nitro could be a very viable option, pity Nitro is illegal in our racing class.

But anyway if you have ever wondered if Nitro could be a good thing with two strokes then this experiment suggests there are real possibilities there.


Illegal? Are you sure? Geez I hardly had any av gas in my av gas. Was that wrong?:Oops:

[ceci]

That is where everything starts to go in different directions! - the racing boys (which this thread is really all about) need as much performance, (ie HP and speed) as is possible, but for the two stroke to get back to universal use by the masses, then a very different type of performance is required - probably much more complicated in order to be used in all sorts of situations!




True this thread is more about obtaining HP.
That is why the work carried out by Mr Jan Thiel and Mr Frits Overmars are more important.
Than those made by GORDON P. BLAIR and Timothy Carl Hickox.
The former try to trap as much fuel air mixture, the latter that the fuel does not come out without burning through the exhausthttps://patentimages.storage.googleapis.com/10/96/82/2821a0c38290ae/imgf000083_0001.png

[2T Institute]

https://www.mahle-powertrain.com/en/experience/mahle-jet-ignition/

Frits, or Wobbly, to your knowledge, has this (or competitors similar systems) ever been trialed in a two-stroke engine? Seems it would bring similar benefits as in a four stroke.

It has...................all top secret at the moment a fellow who has been at it a long while is making good progress

[katinas]

I do use an Autolube pump to deliver to the crankshaft. The crankshaft is hollow with some volume. As the oil pump suddenly delivers more oil as required by load the pump may take time to fill this cavity to a point where oil is flung out via internal drilling to the bigend pin. So I figured if air was continuously flowing it would help carry this oil much quicker to where its needed.
Much like delivering oil to the air inlet stream as almost all normal Autolube systems.
Thats my story and Im sticking to it.

Its about 4t, but maybe in theme. When first type of Honda NR500 engine was tried (with a very high oil consumption and all major rotating parts on rolling bearings), it noticed that the engine power increased when the oil level dropped to the point, when air entered the pump along with the oil. Later, the semi-dry crankcase principle was applied.

[WilDun]

True this thread is more about obtaining HP.
That is why the work carried out by Mr Jan Thiel and Mr Frits Overmars are more important.
Than those made by GORDON P. BLAIR and Timothy Carl Hickox.
The former try to trap as much fuel air mixture, the latter that the fuel does not come out without burning through the exhaust

There is a lot of very interesting stuff coming in here, but it would be sad to see the subject of this thread change too much. - think it was started for the purpose of bringing all the bucket racing guys together with ideas about modifying existing road going machines in order to extract as much power as possible from them for racing purposes.

Covid has sure stopped things for the moment in the direction of competition!

But small road going machines (especially two strokes) are becoming more rare! and if they do make a comeback they will come back in a very different form! - scooters are thriving of course but often they are four strokes and really are quite different to the traditional bucket racer!

The type of racing machine used for Buckets is always a spin off from ordinary small road going machines (which are disappearing fast). Karting seems to be the nearest area where horsepower gaining ideas will come from these days - four strokes didn't seem to thrive there!

I'm not sure whether this thread was ever intended to be specifically for two strokes, but it sure seems to have gone that way!
So it looks like light aircraft two strokes, maybe outboards and of course snowmobiles (both usually too large) will offer some development ideas, but karts are probably the ones to look to for performance improvement ideas!

As I said, racing and road going machines are two very different things but if small road going two strokes (and four stroke) disappear from the roads, then Buckets will have to relax the rules to survive surely?

I think that development of road going two stroke machines (ie motorcycles) will either die out or they will have to improve dramatically (in order to keep the environmentalists, lawmakers etc. happy) but it'll be an uphill battle and manufacturers are there to make money, not to keep us peasants happy, but they do depend on peasants to buy their road going products at the moment!!

[ceci]

I think that development of road going machines (ie motorcycles) will either die out or they will have to improve dramatically (in order to keep the environmentalists, lawmakers etc. happy) but it'll be an uphill battle and manufacturers are there to make money, not to keep us peasants happy, but they do depend on peasants to buy their road going products at the moment!!

If the future is hybrid motorcycles, two-stroke engines may have a place in it, provided they overcome their pollution problems.
But how to overcome these polluting problems, there is no intention to invest in research by manufacturers.

[WilDun]

If the future is hybrid motorcycles, two-stroke engines may have a place in it, provided they overcome their pollution problems.
But how to overcome these polluting problems, there is no intention to invest in research by manufacturers.

Yes, that's how I see it anyway, but I'm sure that others don't see it that way! - (motorcycles are definitely not a priority for vehicle manufacturers).

[Haufen]

If the future is hybrid motorcycles, two-stroke engines may have a place in it, provided they overcome their pollution problems.
But how to overcome these polluting problems, there is no intention to invest in research by manufacturers.

I assume (fear) that motorcycles will go straight to being electric only. There are electric scooters available already, and some motorcycles, too. Hybrids would be heavier for sure and also more expensive due to the double amount of technology.

And with one of the worlds leading two stroke R&D companies recently being closed (Evinrude), my view on the future of two-strokes has recently become darker.





However, the type of propulsion system the manufacturer chose does not matter if you convert your motorcycle to two-stroke afterwards, anyway.

[ceci]

I assume (fear) that motorcycles will go straight to being electric only. There are electric scooters available already, and some motorcycles, too. Hybrids would be heavier for sure and also more expensive due to the double amount of technology.

And with one of the worlds leading two stroke R&D companies recently being closed (Evinrude), my view on the future of two-strokes has recently become darker.





However, the type of propulsion system the manufacturer chose does not matter if you convert your motorcycle to two-stroke afterwards, anyway.

From the rest of the world, as the situation is, I do not know, in my country the main motorcycle manufacturer (Gas Gas) was bought by Torrot, which has its current production of electric scooters, the national manufacturer of automobiles (Seat) is also producing scooters. electrical.
The question is that the useful life of the batteries has limitations that over time lose storage capacity and this can lead to their owners turning them into hybrids when incorporating small combustion engineshttps://upload.wikimedia.org/wikipedia/commons/d/d6/Torrot_Muvi_Lateral_01.jpghttps://www.seat.com/content/global/seat-website/en/casa-seat/es/mo/escooter-125/_jcr_content/par/features/card0_0/cardimage.resizedViewPort.noscale.featureImage.jpg

[Haufen]

From the rest of the world, as the situation is, I do not know, in my country the main motorcycle manufacturer (Gas Gas) was bought by Torrot, which has its current production of electric scooters, the national manufacturer of automobiles (Seat) is also producing scooters. electrical.
The question is that the useful life of the batteries has limitations that over time lose storage capacity and this can lead to their owners turning them into hybrids when incorporating small combustion engines

When my colleague at work complained about the long charging duration and short lifetime of his bicycle battery, I told him about my revolutionary idea for the C-BIKE. Compared to a conventional electric bicycle, it comes with improved passive safety and it can be recharged in under a minute by filling in some sort of 'magic juice'. Also, power and range do not become smaller with lifetime. If you look at it from that perspective, a small two-stroke engine would solve all of his problems.


I think Torrot / GasGas was recently bought by KTM, which might save us from more of those not overwhelmigly sexy scooters :-)
https://www.cyclenews.com/2019/09/article/ktm-buys-gasgas/


Its a shame really, Evinrude were the pioneers of two-stroke direct injection engines and a leader in low emission two-stroke technology. The technology used in the E-Tec snowmobiles was initially a takeover from Evinrude.

On May 27, 2020, BRP announced that they would be retiring the Evinrude brand and would exit the outboard boat motor market [4]. The modern Evinrude E-TEC motors were among the lowest emission and highest power-to-weight ratio outboards produced.
https://en.wikipedia.org/wiki/Evinrude_Outboard_Motors

[wobbly]

Haufen , the real issue is that the Evinrude E tec system , that worked superbly cost a fortune to licence from Bombardier , who use it in all their Snow and Water Ski engines.
Its patented to hell and back - and Bombardier have the money/lawyers to nail anyone trying to copy it commercially , thus there is no available injection system that even comes close in performance
at any cost.
These two sad facts ( performance and cost ) is what is holding back all 2T development around the use of injection , especially allowing an efficient/programmable stratified charge capability.
Niels TPI in some form is a big step forward , but the needed R&D around being able to control the ECU via new some added variable , to track the highly changing pipe efficiency factor , is still in its infancy as far as I know.
The only way for 2T to make it back into mainstream production ( ie the millions of scooters in use daily ) is a simple /cost effective injection system , and or some new mechanical layout development.
NoLuc / Ryger was a giant red herring , so we need something that uses 2Ts inherrent attributes but ameliorates the emmissions downsides.

[WilDun]

Haufen , the real issue is that the Evinrude E tec system , that worked superbly cost a fortune to licence from Bombardier , who use it in all their Snow and Water Ski engines ...................
The only way for 2T to make it back into mainstream production ( ie the millions of scooters in use daily ) is a simple /cost effective injection system , and or some new mechanical layout development.
NoLuc / Ryger was a giant red herring , so we need something that uses 2Ts inherrent attributes but ameliorates the emmissions downsides.

Wobbly, very well said ! - at least you know, I just manage to offer vague suggestions (hunches!) and wait to be blasted by someone I've offended! :rolleyes:

[WilDun]

When my colleague at work complained about the long charging duration and short lifetime of his bicycle battery, I told him about my revolutionary idea for the C-BIKE. ............... a small two-stroke engine would solve all of his problems.

Or maybe both together? - belts/chains/change gears all gone! and perhaps just enough battery to cope with regenerative braking.

[Haufen]

Haufen , the real issue is that the Evinrude E tec system , that worked superbly cost a fortune to licence from Bombardier , who use it in all their Snow and Water Ski engines.
Its patented to hell and back - and Bombardier have the money/lawyers to nail anyone trying to copy it commercially

I agree, that's sad of course. But on the other hand that's what any other company would have done, too. They're in to maximize profits, can't really blame them for that (although the profit thing seems not to have worked out in recent times as can be seen by the closure of Evinrude).


thus there is no available injection system that even comes close in performance at any cost. These two sad facts ( performance and cost ) is what is holding back all 2T development around the use of injection , especially allowing an efficient/programmable stratified charge capability.

I disagree. With automotive DI being the mainstream technology for about a decade now, and the standard being at around 250 bar nowadays, this technology should offer many advantages over the E-Tec at comparable or lower cost. After all, the E-Tec is capable of around 35 bar injection pressure. This means that at higher loads and revs, it has to start injecting when the exhaust port is still open. At low(er) loads like during certification it is very clean, but on full beam it's more or less just as dirty as any other two-stroke. With automotive DI and 250 bar you can inject much more within a given time period. And you have better homogenization before the burn due to the higher injection pressure.



The only way for 2T to make it back into mainstream production ( ie the millions of scooters in use daily ) is a simple /cost effective injection system , and or some new mechanical layout development.

I agree. To make a comeback, the two-stroke has to be (really really) clean and yet still quite simple (and hence cheap).
If one were to combine automotive DI with a rotating exhaust valve drum, that would set the benchmark in clean two-stroke technology, easily.


@all: I am thinking about opening a 'clean two-stroke thread' where we can collect and brainstorm ideas, technologies and the latest news on the market. Does anyone have a proposition in which category such a thread would be put best? There are so many brilliant and capable people on here, I am sure that once it's up and running, we might even get quite far in creating our own clean two-stroke concept. I know that's a long path, but if the option is no more two-strokes in the future, then I am all in.

[TZ350]

I am thinking about opening a 'clean two-stroke thread' where we can collect and brainstorm ideas, technologies and the latest news on the market. Does anyone have a proposition in which category such a thread would be put best?

Clean 2T and 2T revival is very interesting. My two cents worth. Continuing here is OK or adding to this thread https://www.kiwibiker.co.nz/forums/showthread.php/185773-Speeduino-2T-EFI-Project might be interesting or a new one altogether but still within the Bucket forum where most of the inventiveness with new ideas is done.

[Flettner]

Yes a separate thread might be good. But are the best ideas going to be published? Just to get used by industry with no recognition as to where the concept came from. I was / am all for publishing everything but if its any good it will get pinched. We will all need to understand this up front, and that 'industry' will try to patent it for themselves, so we will have to keep a good eye on provisional patents. Rats run 'industry'.
You can actually provisionally patent stuff relatively easily and cheaply, but you will only have 12 months after that, full patent, or let it go. And the buggers (rats) know this.

Edit, you can get up to eighteen months protection but that will cost a little extra.

[WilDun]

I am thinking about opening a 'clean two-stroke thread' where we can collect and brainstorm ideas, technologies and the latest news on the market. Does anyone have a proposition in which category such a thread would be put best? There are so many brilliant and capable people on here, I am sure that once it's up and running, we might even get quite far in creating our own clean two-stroke concept. I know that's a long path, but if the option is no more two-strokes in the future, then I am all in.

Most of the younger guys on the forum probably won't even remember two strokes on the roads (it's that bad!) and if it's not competition oriented they won't become interested (nor will it be if we are gunning for economy and cleanliness).

Those who are interested in the engineering of it all, young or old of course, will be keen!

Everyone interested in bikes, especially four stroke need to take notice too, because four strokes will most probably go down the same path the two strokes have gone down and eventually all motorcycles will be legislated off the roads (unless they have roll cages or something else ridiculous) by the powers that be - we didn't think at first that sort of thing could possibly ever come up, but it was proposed - by a politician in America way back! - however they will still find some dumb ass safety regulation to apply to complete the job!

I think that you'll have to spend a bit of time going over all the other threads and find out just who your interested people really are - or try and get some interest started! - difficult one - do your best. :niceone:

BTW we don't know if you are a Kiwi or not! - some possibly do.

[Niels Abildgaard]

I agree. To make a comeback, the two-stroke has to be (really really) clean and yet still quite simple (and hence cheap).
If one were to combine automotive DI with a rotating exhaust valve drum, that would set the benchmark in clean two-stroke technology, easily.


@all: I am thinking about opening a 'clean two-stroke thread' where we can collect and brainstorm ideas, technologies and the latest news on the market. Does anyone have a proposition in which category such a thread would be put best? There are so many brilliant and capable people on here, I am sure that once it's up and running, we might even get quite far in creating our own clean two-stroke concept. I know that's a long path, but if the option is no more two-strokes in the future, then I am all in.

Please go ahead and start a new thread with clean two strokes.The game of wringing more power out of a given amount of cubic is dying.
Two strokes can improve environmental issues on small aircraft engines.There is no catalyst demand and some of the pigs use leaded petrol.

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

[lohring]

I think opposed piston two strokes have a future. They have a long history and seem to have advantages. I'm waiting for Flettner's latest impatiently.

Lohring Miller

[Flettner]

I think opposed piston two strokes have a future. They have a long history and seem to have advantages. I'm waiting for Flettner's latest impatiently.

Lohring Miller

Me too, waiting impatiently.

[F5 Dave]

start a Givealittle page so Neil can give up paid work and do some serious development. I think Speedpro had mentioned something along these lines previously.

[WilDun]

start a Givealittle page so Neil can give up paid work and do some serious development. I think Speedpro had mentioned something along these lines previously.

Yeah! ..... and backed up by a "think tank" second to none on this forum - wow! - sort of like "way to go" open source - gotta be the last chance for a 2T future! ...... wait a minute, isn't a camel really a horse, designed by a committee?

We'll need to have a president, a vice president, a treasurer/pay clerk /financial adviser, mechanical adviser, expert on the law regarding patent rights, somewhere to have discussions, someone to make the coffee and generally tidy up, plus a couple of dogsbody designer/draughtsmen (if required) - and possibly someone who knows what he is doing! that's the daunting part of it all! :facepalm: - sounds like the "Men's Shed"! :msn-wink:

Seriously though, a thread along the lines of what is being considered would be great and all we really need to do is listen to those who have "been there" but at the same time, have the ability for everyone to put forward some proposals, (good or bad), accepting the fact that we might be talking crap and get crucified for it! (I do!) - BTW no place for PC crap here!.
The clean two stroke should be the big focus, with minimal digressing from the subject - now lots of other threads around here for that!

- go for it Haufen! :niceone:

[andreas]

Instead of digging filthy pits and Bangladeshian kids recycling metals for those stupid batteries- why isn't the hydrogen combustion engine utilized again?

[Flettner]

Instead of digging filthy pits and Bangladeshian kids recycling metals for those stupid batteries- why isn't the hydrogen combustion engine utilized again?

Or ethanol, works for me.

[WilDun]

Or ethanol, works for me.

Ethanol probably, but not in cities - (dangerous fumes in large concentrations I'm told), it's probably the most accessable, but would
we then be depriving the poor of food? (might be more profitable for energy than for food). Also, imagine a pub with no beer - very lonesome!.

Yes the question of what to do with used batteries is not often broached!

Japan is persevering with Hydrogen - might save the Wankel concept - don't think Mazda have given up on it yet!

[Flettner]

Will D, you are thinking methanol, its the dangous one, quite different fuels.

[husaberg]

Will D, you are thinking methanol, its the dangous one, quite different fuels.

i dont know, the ethanol is responsible for some dubious decisions also.

https://static.tvtropes.org/pmwiki/pub/images/ten_with_a_two.jpg
https://i.pinimg.com/originals/84/1d/6b/841d6b036efc271c0308b7dd108a0220.gif

[Vannik]

Hydrogen is not dead:

https://www.h2-view.com/story/hyundai-ships-first-hydrogen-trucks-to-switzerland/

[WilDun]

Will D, you are thinking methanol, its the dangous one, quite different fuels.

Yeah, sorry Neil, ......... slow learner! - I was told that before but forgot!
BTW they say that the common "meths" which you can get everywhere, no longer contains any methanol at all, but the blue dye in it (which makes you violently ill) is now impossible to distill out of it! - it's now pure ethanol! (that's how it is in this country anyway).

Vannik,
I had no idea that the fuel cell was already up and running! - if it continues (and I don't doubt it will), I wonder where the combustion engine (both 2 and 4 stroke) will stand? - Looks like they will soon be left out of the equation entirely! - that's going to piss a lot of people off and may force many of them to drink ethanol instead, just to dull the pain! so the Hydrogen and Ethanol producers have a rosy future - and the Greenies will no longer have any gripes - what a wonderful world! :rolleyes:

Interested to find out if the fuel cell's life is any different to that of a "normal" battery.

Husa,
It's amazing how a big glass of alcohol can change your perception of things!

[ceci]

Sorry for being the video in Spanish.
This is one of the reasons why I think they will see hybrid bikes in the future.


https://www.youtube.com/watch?v=RR2U3dTpUrg

[Frits Overmars]

Sorry for being the video in Spanish.This is one of the reasons why I think they will see hybrid bikes in the future. Agradable de Mercedes que el generador está incluido. ¿Pero por qué ese auto no tiene una barra de remolque?:confused:

[ceci]

Agradable de Mercedes que el generador está incluido. ¿Pero por qué ese auto no tiene una barra de remolque?:confused:

Hi Frits.

I know you have understood the audio of the video, and the owner of the car complains that it will take a day to load.
BMW on this bike will also include the gift generator?


https://youtu.be/oW0ShDRggts

[Frits Overmars]

Hi Frits. I know you have understood the audio of the video, and the owner of the car complains that it will take a day to load.
BMW on this bike will also include the gift generator?

https://youtu.be/oW0ShDRggtsI will hold back my opinion on the aesthetics of that vehicle, but for heaven's sake, how can a motorcycle manufacturer like BMW release a promotional film for motorcycling without a helmet? Not even Harley-Davidson would be so daft.

[WilDun]

I will hold back my opinion on the aesthetics of that vehicle, but for heaven's sake, how can a motorcycle manufacturer release a promotional film for motorcycling without a helmet?

Methinks the next hundred years will be very different to that! - and anyway, dickheads really shouldn't be wearing helmets!

[jonny quest]

I have a fuel injected 2 stroke scooter. 2001 Aprilia SR50 Ditech. I bought it not running. Was at 2 shops that couldn't figure out how to fix it before I bought it. It sat for 2 years in my possession before I decided to look at it last weekend. Got it running in an hour.

Runs pretty good until the fuel pressure regulator starts acting funny. I'm pretty sure this was the original culprit of problem for previous owner. Regulator isn't available for separate purchase.

I'm installing an external adjustable regulator and then doing some mods, and having a little fun with trying performance mods

[ceci]

I have a fuel injected 2 stroke scooter. 2001 Aprilia SR50 Ditech. I bought it not running. Was at 2 shops that couldn't figure out how to fix it before I bought it. It sat for 2 years in my possession before I decided to look at it last weekend. Got it running in an hour.

Runs pretty good until the fuel pressure regulator starts acting funny. I'm pretty sure this was the original culprit of problem for previous owner. Regulator isn't available for separate purchase.

I'm installing an external adjustable regulator and then doing some mods, and having a little fun with trying performance mods


I guess if you can't find it it's because it's no longer being marketed

https://www.canplastics.com/features/polyphthalamide-replaces-aluminum-in-fuel-air-rail/

[Condyn]

Posting here due to lack of general activity on the EngMod thread. What is the best way to accurately measure the crankcase compression ratio for the program? At first I thought it was straight forward, but now I am questioning my sanity. My thought was to first stick my burette into each transfer window at BDC (large bore perk) to make sure they were actually full (or as close to full as possible without spilling over the piston) then bring the piston to TDC and fill the rest of the way through the hole I drilled in the piston. Already I created an air pocket in the pin and the roofs of the transfer ducts. I know the Fluid level will equalize itself to an extent, but I cannot see a logical way to get the air all out.

And finally I have a wretched piston port, so how am I to seal the inlet port, and where is the proper place to seal it for this measurement?

[wobbly]

CCR is easy - drill a small hole in a piston , sit it at TDC and fill to the top. This number is an option in the EngMod CCR input and of course includes the transfer volume.
Seal the inlet port using plastercine - oil the piston with it covering the port , push the plastercine into place using the skirt as a former.
Then run the piston up to TDC.
You can seal Aux ports the same way if they are exposed at TDC ( they shouldnt ).

[Condyn]

Thanks for the advice. I will try plastercine. I have a matching piston with a hole drilled in it. I am concerned about having air pockets in the ducts.

[andreas]

If the ports arn't cleared under the piston at tdc- just make sure they are.

[wobbly]

You can easily drill holes in the piston skirt to eleiminate pockets of air trapped in the ducts.

[ken seeber]

Yes a separate thread might be good. But are the best ideas going to be published? Just to get used by industry with no recognition as to where the concept came from. I was / am all for publishing everything but if its any good it will get pinched. We will all need to understand this up front, and that 'industry' will try to patent it for themselves, so we will have to keep a good eye on provisional patents. Rats run 'industry'.
You can actually provisionally patent stuff relatively easily and cheaply, but you will only have 12 months after that, full patent, or let it go. And the buggers (rats) know this.

Edit, you can get up to eighteen months protection but that will cost a little extra.

Totally agree with creating a dedicated thread. Something simple like: "A clean 2 stroke". Probably under Buckets, though Oddball is another option.

[Flettner]

Twin rotary valves.
Ive changed my mind on the induction, these cases are now out dated.

[F5 Dave]

Unlike the tablecloth, which in Kermit green, I think everyone will agree is a classic.

[Frits Overmars]

This could become be a high and mighty engine Neil. Are you contemplating a chin-rest on the upper crankcase?:msn-wink:
346393

[jfn2]

My question is about the shape of the transfer runners. My question is do I trim some of the bottom off or is it better to leave it alone? The red lines show where I would taper the runner. Should I make it more of a 2 1/2 finger teacup handle rather than a 4 finger "D" handle?
346394

[katinas]

Hi, with this Kx 65 cylinder is good opportunity to round the cylinder wall inner edge (green) only and leave the entrance to trans edge as it is, before the first test.

[jfn2]

Katinas:
Yes, thank you for reminding me of that. I have to run the bike in stock form first, which I plan to do the first of next week on the dyno. I will post all results.

[katinas]

Katinas:
Yes, thank you for reminding me of that. I have to run the bike in stock form first, which I plan to do the first of next week on the dyno. I will post all results.

It would be really interesting.
Other thing to worth to try, milled spark plug, that Frits and Jan advice to try, is very helpful.
With this year Huqvarna TC 85 we ended at 31,53 hp with std spark plug.
Then milled plug 31,1 hp
Then retard ignition with woodruff key (approx 3mm retard at lobe) 32.06 hp 11876 rpm (from rear wheel with triangular 16 inch woody 1992 GP Dunlop front slick tire)
Std plug with retarded ignition 31.45 hp and lower everywhere except at over 12500rpm.
Looks like milled plug shortens the burning time, maybe due to the plug inserted deeper into the chamber, closer to piston and/or due to the more open ceramics.

[Flettner]

This could become be a high and mighty engine Neil. Are you contemplating a chin-rest on the upper crankcase?:msn-wink:
346393

Yes it is tall, but who cares for the moment, test. It fits in the 2010 YZF frame I have.

If I find the layout works I can build a new version with the cylinder laying down / inclined to fit a motorcycle better.

My other passion, autogyros, this type of engine is ideal, wide not a problem, short front to back ideal. The central crank joining gears come in handy for prop reduction, like Junkers. I also have a surprise there.

[wobbly]

Tapering down the green area will effectively reduce the transfer duct volume , this it may not like.
Remember back to the old TZ cylinders , where it proved that the A port duct shortened by 10mm with the B port duct left stock length made a good increase.
Putting the bore edge radius on the duct entry has worked every time for me.

[wobbly]

Katinas , can you post a pic of the " milled " plug nose please.

[jfn2]

Wobbly is this what you mean?

346396

[F5 Dave]

Tapering down the green area will effectively reduce the transfer duct volume , this it may not like.
Remember back to the old TZ cylinders , where it proved that the A port duct shortened by 10mm with the B port duct left stock length made a good increase.
Putting the bore edge radius on the duct entry has worked every time for me.
So it draws from that duct like reservoir ready to be used you are perhaps implying? So even though it will continue to draw from the cases that plug ready is beneficial, even if in some cases there is reverse flow first.

When I modified my MB100 I lowered the port floor to match at BDC, possibly 2mm, then glued a curved section onto the inner wall and worked for ages to get it even and checked shape with moulding rubber again and again so the passage didn't contract then expand at the port.
Lost 1.5hp out of 27.5.

I suspect that I did some good things but then took 2 steps back by reducing the volume, and my next step was to be to grind more area in the outside of the cup handle. . . . and then I had a bout of gravity and development stopped. Need to urge the new owner to let me loose on the barrel when its next off.

Does that make sense?

[ceci]

Totally agree with creating a dedicated thread. Something simple like: "A clean 2 stroke". Probably under Buckets, though Oddball is another option.

Hi Ken. Excuse me for the nonsense that I am going to suggest, but I am beginning to wonder if we have not gone in the wrong direction regarding the anti-pollution solution.
The denial of the manufacturers to the use of an auxiliary piston pump (attempt to keep the 2S as simple) to carry out a load stratification (solution to the short-circuit effect) led the researchers to choose the lines of research in which the crankcase only can have clean air, this research line begins with "Multi-Layer Stratified Scavenging (MULS)" by Blair G. P, until the rest of the investigations both with auxiliary compressor (pre-pneumatic injection system) and without it.
And why not twirl he omelette "a typical Spanish saying", instead of using the air from the compressor to create the mixture of air and fuel, we use it to create a wall as a solution to the short circuit


I have a fuel injected 2 stroke scooter. 2001 Aprilia SR50 Ditech. I bought it not running. Was at 2 shops that
couldn't figure out how to fix it before I bought it. It sat for 2 years in my possession before I decided to look at it last weekend. Got it running in an
hour.

Runs pretty good until the fuel pressure regulator starts acting funny. I'm pretty sure this was the original culprit of problem for previous owner. Regulator isn't available for separate purchase.

I'm installing an external adjustable regulator and then doing some mods, and having a little fun with trying performance mods

In case you do not end the problems of the fuel pressure regulator and decide to change to the use of a carburetor (something very common "if you look in the Aprilia forum there are many cases").
Why not try something different, keep the air injection system (create the "avoid short circuit" wall) together with a carburettor supplyhttps://www.apriliaforum.com/forums/attachment.php?attachmentid=227541&d=1374601693&thumb=1

[katinas]

Wob, add plugs from testing with NS engine, all milled on lathe, but my friend doing the same with a grinder, even on 10 mm plugs for sx 50/65.
Its good to use 22mm deto type plugs and after milling 3 mm, use them like 19mm with std washer. Otherwise some correction on the head is needed.

With fixed advance timing on kart engine, maybe you noticed that, resistor plug together with bigger gap, little bit delay ignition and opposite, non resistor plug with small gap, advances ignition. I am not sure, but sometimes, engines react that way. Testing with Suzuki RGV 250, that sapc stock ignition timing is set at safe retarded zone and pick ups is fixed. I try non resistor plug with small gap and non resistor plug cap. Engine goes more aggressive. But maybe this is just coincidence.

[WilDun]

Hi Ken. Excuse me for the nonsense that I am going to suggest, but I am beginning to wonder if we have not gone in the wrong direction regarding the anti-pollution solution.
The denial of the manufacturers to the use of an auxiliary piston pump (attempt to keep the 2S as simple) to carry out a load stratification (solution to the short-circuit effect) led the researchers to choose the lines of research in which the crankcase only can have clean air, this research line begins with "Multi-Layer Stratified Scavenging (MULS)" by Blair G. P, until the rest of the investigations both with auxiliary compressor (pre-pneumatic injection system) and without it.
And why not twirl he omelette "a typical Spanish saying", instead of using the air from the compressor to create the mixture of air and fuel, we use it to create a wall as a solution to the short circuit

In case you do not end the problems of the fuel pressure regulator and decide to change to the use of a carburetor (something very common "if you look in the Aprilia forum there are many cases").
Why not try something different, keep the air injection system (create the "avoid short circuit" wall) together with a carburettor supply

I am fairly certain that Neil (Flettner) did use a plug of fresh air between the charges in his earlier OP engine - but he can speak for himself! - (Blair was using it in a conventional cylinder).
Also, using the crankcase as an (under piston) pump has the disadvantage of preventing the use of four stroke type lubrication (either wet sump or dry sump) will have oil suspended in the air, being burnt with the charge and not addressing the problem of a smoky exhaust, which was really the cause of the whole road going two stroke versus public 'misconception' in the first place!

I hope I have not misunderstood it all!

Sorry Ken, I only butted in because I'll be going to bed soon! ..... :yawn:

[Frits Overmars]

My question is about the shape of the transfer runners. My question is do I trim some of the bottom off or is it better to leave it alone? The red lines show where I would taper the runner. Should I make it more of a 2 1/2 finger teacup handle rather than a 4 finger "D" handle?Radiusing the bore edge, like Katinas and Wobbly suggest, works every time. A radius of 6% of the bore would be a good value.
346413 346414

As for the remainder of the transfer duct inner walls, it should be noted that the smallest radius will be decisive for flow detachment. It's no use making that radius big in some places when it reduces the radius in other places, so go for a the biggest constant radius that can be fitted in within the available space.
346415

[katinas]

DiTech
Remember the Aprilia manufacturer's strong recommendation for dealers. Before selling DiTech, after the first start of the engine run it as soon as possible at maximum speed, so that the preservative oil would not burn into the nozzle and the spray system would be cleaned as soon as possible.
DiTech biggest problem was not properly atomized fuel spray and because of that, fouled small 10 mm nearly up side down located plug. Maybe bigger 14 mm vertical located plug resist better.

Honda RS 500 with Hans Humel's cylinders. Just want to take under the armpit.

[jonny quest]

On a Ditech SR50 the fuel is injected through the head as piston closes exhaust port.

It still has a standard looking cylinder with case reed.

I'd like to get more performance out of cylinder, but transfers are just moving air.

I'd like to hear some of your ideas on how to increase performance with the cylinder porting

[Haufen]

Thank you all for your encouragement, I just created a new thread under Buckets.

https://www.kiwibiker.co.nz/forums/showthread.php/188376-the-clean-two-stroke-thread?p=1131166129#post1131166129

I am looking forward to many interesting discussions!



Clean 2T and 2T revival is very interesting. My two cents worth. Continuing here is OK or adding to this thread https://www.kiwibiker.co.nz/forums/showthread.php/185773-Speeduino-2T-EFI-Project might be interesting or a new one altogether but still within the Bucket forum where most of the inventiveness with new ideas is done.

Thanks, I was thinking back and forth over the last couple of day and then went for a seperate thread under buckets. Let's see how that goes.


Yes a separate thread might be good. But are the best ideas going to be published? Just to get used by industry with no recognition as to where the concept came from. I was / am all for publishing everything but if its any good it will get pinched. We will all need to understand this up front, and that 'industry' will try to patent it for themselves, so we will have to keep a good eye on provisional patents. Rats run 'industry'.
You can actually provisionally patent stuff relatively easily and cheaply, but you will only have 12 months after that, full patent, or let it go. And the buggers (rats) know this.

Edit, you can get up to eighteen months protection but that will cost a little extra.

I fully agree, and I have also experienced the same as you with one of my ideas in the past. The company was not as big as KTM in my case, but it made me much more attentive to intellectual property and the behaviour in the industry. Good thing is, once something has been published, it is free for everyone to use. Other (cheaper) variants to a patent are for example sending some new stuff to one's self in a sealed parcel or envelope and best with a post stamp showing the date directly on the seal. But these are problems we yet have to have, although it's never too early to keep this in mind.



I think that you'll have to spend a bit of time going over all the other threads and find out just who your interested people really are - or try and get some interest started! - difficult one - do your best. :niceone:

BTW we don't know if you are a Kiwi or not! - some possibly do.

if you happen to know some people that you think might be perfect contributors to the thread, please give them an hint.

I am from Europe, but if I ever happen to move to NZ, one of the first things on my list is getting a bucket, that's for sure!


Please go ahead and start a new thread with clean two strokes.The game of wringing more power out of a given amount of cubic is dying.
Two strokes can improve environmental issues on small aircraft engines.There is no catalyst demand and some of the pigs use leaded petrol.

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

Absolutely, even if two-strokes might not get 'car engines clean' in the end, every bit cleaner than now will open up new possibilities in other areas.



Seriously though, a thread along the lines of what is being considered would be great and all we really need to do is listen to those who have "been there" but at the same time, have the ability for everyone to put forward some proposals, (good or bad), accepting the fact that we might be talking crap and get crucified for it! (I do!) - BTW no place for PC crap here!.
The clean two stroke should be the big focus, with minimal digressing from the subject - now lots of other threads around here for that!

- go for it Haufen! :niceone:

Yes, let's see what happens. Worst case is we learn something


Totally agree with creating a dedicated thread. Something simple like: "A clean 2 stroke". Probably under Buckets, though Oddball is another option.

Just what I thought.

-------

The starting post in the new thread is not yet completed (emissions part still in progress), but please just start right away, no need to wait.

[JanBros]

I don't think I'd be interested in a 2-stroke without exhaust port(s) and without an expansion chamber, even if it's very clean.

[Flettner]

Twin rotary valves, although these cases are for a uniflow project, they are able to be set up as a twin rotary valve. Crank can be 48 up to 58, so plenty of room to make it a 100cc bucket engine. Gearbox is 175 Kawasaki. Clutch is 250F. Bit of paint and a sand next.

[jamathi]

It would be really interesting.
Other thing to worth to try, milled spark plug, that Frits and Jan advice to try, is very helpful.
With this year Huqvarna TC 85 we ended at 31,53 hp with std spark plug.
Then milled plug 31,1 hp
Then retard ignition with woodruff key (approx 3mm retard at lobe) 32.06 hp 11876 rpm (from rear wheel with triangular 16 inch woody 1992 GP Dunlop front slick tire)
Std plug with retarded ignition 31.45 hp and lower everywhere except at over 12500rpm.
Looks like milled plug shortens the burning time, maybe due to the plug inserted deeper into the chamber, closer to piston and/or due to the more open ceramics.

We tried this at Aprilia about 20 years ago. It gave about 0,7 HP more. The problem was that we could not possibly modify hundreds of plugs to satisfy all our customers. Asking the plug manufacturer to produce plugs that way would have meant to throw our advantage away...… So it was never done anymore.... Another interesting thing: a plug was returned to us after a race with the earth electrode completely broken off. But it had finished the race, so it was tried on the dyno: about 1HP more! Very nice, until after a couple of runs the ignition coil failed.... It might have worked with a better ignition coil.... Which we didn't have!

[jamathi]

Radiusing the bore edge, like Katinas and Wobbly suggest, works every time. A radius of 6% of the bore would be a good value.
346413 346414

As for the remainder of the transfer duct inner walls, it should be noted that the smallest radius will be decisive for flow detachment. It's no use making that radius big in some places when it reduces the radius in other places, so go for a the biggest constant radius that can be fitted in within the available space.
346415

The Aprilia cylinders had a constant inner and outer radius in the transfer ducts. Doing this gave a really big improvement!. The narrowest point of the duct was the port itself, 12,25mm. Transfer timing remained the same for all 12 years of development. Maybe I should have tried a shorter timing, now I regret that I never did.... One of the biggest improvements came from making the port UNDERSIDE being made exactly as high as the piston in BDC! Many cylinders are wrong in this respect, the piston top causing severe disturbance to transfer flow, and detonation.... The most sensitive point in the cylinder proved to be the A-port front side, the nearest to the exhaust port. It's direction was machined to be very much angled away from the exhaust, as far as material thickness allowed. In this way it could be made wider, giving good improvements. Wall thickness was 1,5mm between water passage and duct.

[katinas]

Jan, it is very interesting, thank you for your words.
Denso racing plugs side platinum electrode is pressed in, so it is possible to adjust gap or even can be easily pulled out. NGK side platinum electrode is solid with plug body.
With Denso IA, two times ceramic falls down and every time when the engine goes very well.

[jamathi]

Jan, it is very interesting, thank you for your words.
Denso racing plugs side platinum electrode is pressed in, so it is possible to adjust gap or even can be easily pulled out. NGK side platinum electrode is solid with plug body.
With Denso IA, two times ceramic falls down and every time when the engine goes very well.

We had the same problem, seems to be caused by plug overheating. We solved it by getting the cooling water closer to the plug. After that it never happened again.

[katinas]

Another interesting thing: a plug was returned to us after a race with the earth electrode completely broken off. But it had finished the race, so it was tried on the dyno: about 1HP more! Very nice, until after a couple of runs the ignition coil failed.... It might have worked with a better ignition coil.... Which we didn't have!

Very interesting. With so big gap, maybe is some delay of spark moment, but faster burning because of more waiting electrons, accumulated on the electrode, burst during the same time interval. Just a guess

[jfn2]

Thank you Jan, Frits and Katinas for answering my question about the transfer tunnel. Right now I don't see much I can do about the outer tunnel wall radius, but I can reshape the inner wall beginning radius after I radius the bore edge. I will try the other mods as I go along.

[jonny quest]

That's definitely an option, keeping air pump and going with a carb.

I also made a post asking for thoughts on porting an air only cylinder that is of typical 2 stroke configuration.

In a sir/fuel cylinder we're trying to fill bore as much as possible, but keep fuel away from exhaust port.

In an air only cylinder is it still an advantage to have a Schnuerle style transfers? Should the transfer roof angle just be really steep in an air only cylinder?


Hi Ken. Excuse me for the nonsense that I am going to suggest, but I am beginning to wonder if we have not gone in the wrong direction regarding the anti-pollution solution.
The denial of the manufacturers to the use of an auxiliary piston pump (attempt to keep the 2S as simple) to carry out a load stratification (solution to the short-circuit effect) led the researchers to choose the lines of research in which the crankcase only can have clean air, this research line begins with "Multi-Layer Stratified Scavenging (MULS)" by Blair G. P, until the rest of the investigations both with auxiliary compressor (pre-pneumatic injection system) and without it.
And why not twirl he omelette "a typical Spanish saying", instead of using the air from the compressor to create the mixture of air and fuel, we use it to create a wall as a solution to the short circuit



In case you do not end the problems of the fuel pressure regulator and decide to change to the use of a carburetor (something very common "if you look in the Aprilia forum there are many cases").
Why not try something different, keep the air injection system (create the "avoid short circuit" wall) together with a carburettor supplyhttps://www.apriliaforum.com/forums/attachment.php?attachmentid=227541&d=1374601693&thumb=1

[katinas]

On a Ditech SR50 the fuel is injected through the head as piston closes exhaust port.

It still has a standard looking cylinder with case reed.

I'd like to get more performance out of cylinder, but transfers are just moving air.

I'd like to hear some of your ideas on how to increase performance with the cylinder porting

Hi, we never play with DiTech, but maybe modifications similar like with the carb. Or even more attention on things that prevent losses air to exhaust, as the air is less inertial than mix and it is even harder to hold high density air streams in the compact shape, coming from the transfers. And less resistance for reverse flow. And no cooling effects for transfers. But less drag on pumping. Interesting about DiTech injection rpm limit. Maybe all works must be done for mid rpm.

I remember funny DiTec repair, fifteen years ago. Accidentally, two Ditec Rs50 had to be repaired at the same time. One does not have a spark and the spray system does not work, other with air leakage from crankcase pump. I swapped cdi from other and everything worked. I wanted to call the client to order a new cdi, but before that decide to connected the old cdi again and everything worked. It was the fastest repair.

[wobbly]

I forgot to reply to you F5 Dave - the volume of mixture in the transfer duct total is in excess of that getting into the cylinder , so in reality there is no flow from the
case ,thru the duct and out the port at BDC.
Thus in many cases the duct volume may be too big , and maybe this is a downside due simply to inertia effect.
Some are too small , and the energy needed to try and move mixture from the far end of the duct is too great - again a down side on power.

I will try the milled spark plug idea on a KZ2 as soon as I can , we have a tech rule about no plug body intrusion into the combustion space past the end of the head threads.
But with the nose sticking out 3mm , and the body flush , this puts the ionizing spark gap way closer to the middle of the chamber - and its legal as.
Will post dyno graph as soon as its done.

[lodgernz]

This is interesting, the long-dreamed-of "Free Piston" engine at last appears to work.
This iteration of it appears to make no attempt to drive wheels, but uses the motion of the rods to produce electricity, which obviously can then drive wheels or whatever.

https://www.aquariusengines.com/technology/

[F5 Dave]

I forgot to reply to you F5 Dave - the volume of mixture in the transfer duct total is in excess of that getting into the cylinder , so in reality there is no flow from the
case ,thru the duct and out the port at BDC.
Thus in many cases the duct volume may be too big , and maybe this is a downside due simply to inertia effect.
Some are too small , and the energy needed to try and move mixture from the far end of the duct is too great - again a down side on power.

. . .
Ok thanks, gee ill have to measure that. I've seen some enormous cavity transfers. These in comparison are small so to measure volume and compare with something less pedestrian should give me a ratio vs cc of engine.

So why would bore to duct radius help so much? As the plug of gas is blown then sucked into the cylinder it needs to be replaced i guess with least resistance.

[husaberg]

I forgot to reply to you F5 Dave - the volume of mixture in the transfer duct total is in excess of that getting into the cylinder , so in reality there is no flow from the
case ,thru the duct and out the port at BDC.
Thus in many cases the duct volume may be too big , and maybe this is a downside due simply to inertia effect.
Some are too small , and the energy needed to try and move mixture from the far end of the duct is too great - again a down side on power.

I will try the milled spark plug idea on a KZ2 as soon as I can , we have a tech rule about no plug body intrusion into the combustion space past the end of the head threads.
But with the nose sticking out 3mm , and the body flush , this puts the ionizing spark gap way closer to the middle of the chamber - and its legal as.
Will post dyno graph as soon as its done.


Ok thanks, gee ill have to measure that. I've seen some enormous cavity transfers. These in comparison are small so to measure volume and compare with something less pedestrian should give me a ratio vs cc of engine.

So why would bore to duct radius help so much? As the plug of gas is blown then sucked into the cylinder it needs to be replaced i guess with least resistance.

Frits or Jan gave a very elegant answer on the dutch site to that question

i cant find it and clearly lack the wisdom to paraphrase it either but he gave a rule of thumb or an indication of the size for transfer volume vs cylinders

Jan said this though
One thing I am sure about is: always give priority to flow over crankcase volume!

[Frits Overmars]

I will try the milled spark plug idea on a KZ2 as soon as I can , we have a tech rule about no plug body intrusion into the combustion space past the end of the head threads.
But with the nose sticking out 3mm , and the body flush , this puts the ionizing spark gap way closer to the middle of the chamber - and its legal as.Milling the spark plug puts the spark gap closer to the middle of the camber. It also promotes access of the mixture to the gap between the electrodes, helping it to replace the burned gases with stuff that still wants to burn. And it cools the plug.
346431

Speaking of tech rules: the above rule seems so simple; what could possibly go wrong? Well, I would claim that the mass electrode is part of the plug body, so this simple rule simply renders all present-day spark plugs illegal :devil2:.

[TZ350]

Interesting about DiTech injection rpm limit.

If they are doing all their injecting after the exhaust is closed then they have very little time to get the fuel in there before the compression pressure becomes greater than the injectors fuel supply pressure. Even if they had enormous injector pressure they still have very little time because the distance between exhaust closing and ignition would only be 60-70 crankshaft degrees at most.

A fuel injector takes time to open and start flowing fuel and then there has to be some time left for all the injected fuel to evaporate. All this severely limits the rpm possible with direct injection. Vertically downwards B transfer port injection overcomes a lot of those time limits because it can inject for 360 crank degrees but eventually it hits its own time ceiling.

346435 Direct Injection. (very time and therefor RPM limited)

346434 B port injection. (not so time and RPM limited)

346432 346433 The father of B port injection.

The modified Yamaha YZ250 cylinder above was running well before KTM's EFI bike. In fact KTM went down several wrong roads before copying this YZ250.

<iframe width="560" height="315" src="https://www.youtube.com/embed/hOGZ5llowoU" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

[andreas]

If they are doing all their injecting after the exhaust is closed then they have very little time to get the fuel in there before the compression pressure becomes greater than the injectors fuel supply pressure. Even if they had enormous injector pressure they still have very little time because the distance between exhaust closing and ignition would only be 60-70 crankshaft degrees at most.

A fuel injector takes time to open and start flowing fuel and then there has to be some time left for all the injected fuel to evaporate. All this severely limits the rpm possible with direct injection. Vertically downwards B transfer port injection overcomes a lot of those time limits because it can inject for 360 crank degrees but eventually it hits its own time ceiling.

346435 Direct Injection. (very time and therefor RPM limited)

346434 B port injection. (not so time and RPM limited)

346432 346433 The father of B port injection.

The modified Yamaha YZ250 cylinder above was running well before KTM's EFI bike. In fact KTM went down several wrong roads before copying this YZ250.

<iframe width="560" height="315" src="https://www.youtube.com/embed/hOGZ5llowoU" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Is there any advanage pre-heating the fuel?

[katinas]

And it cools the plug.
.

Yes, after the first test on the track we were surprised that electrode color indicated cooler run than before.

[Vannik]

Milling the spark plug does put the spark gap closer to the middle of the camber.It also promotes access of the mixture to the gap between the electrodes, helping it to replace the burned gases with stuff that still wants to burn. And it cools the plug.
346431

Speaking of tech rules: the above rule seems so simple; what could possibly go wrong? Well, I would claim that the mass electrode is part of the plug body, so this simple rule simply renders all present-day spark plugs illegal :devil2:.

Frits, maybe this is of interest?

346442

[katinas]

Rob, I found this video with Sr 50 DiTech max rpm, but maybe this is not a limit, because of cylinder/pipe/reed restrictions.
https://www.youtube.com/watch?v=1kj1rcnFDpo

If it is a limit for Ditech injection, so cylinder/pipe/reed must adapted for 6000 to 10000 rpm interval.

[jonny quest]

And then we have the pipe design aspect of a fuel injected engine where fuel is only above the piston.

Pipe will react the same on EO, but transfer opening... I think it would benefit from steep angles on header and diffuser.

What are your thoughts?

TZ350, the Ditech uses high fuel pressure, along with an air injector in head. They actually run really well when the multitude of harmonious fuel and air delivery system is working properly.

[Frits Overmars]

Frits, maybe this is of interest?
346442It is, thank you Neels :niceone:

[jfn2]

Neels, what is the little curlique at the bottom of the ground electrode in the first diagram?

[Vannik]

Neels, what is the little curlique at the bottom of the ground electrode in the first diagram?

I have no idea, I assume it is a shadow as it does not show up anywhere else in the thesis.

[TZ350]

TZ350, the Ditech uses high fuel pressure, along with an air injector in head. They actually run really well when the multitude of harmonious fuel and air delivery system is working properly.

I don't doubt they run really well. I have seen Video of the Ditech and it looks very good. But real God's given "Time" is their enemy and limits their possible RPM compared to a carburetor engine.

I think there is no amount of mechanical or pipe design that can make any more real "Time" for direct injection to get things done. This "Time" limit is much less of a problem with B port injection and B port engines can more than compete with carburetor engines for outright performance and RPM.

https://youtu.be/wUleM_8LoP4

https://youtu.be/aIyDOmalP1U

A standard Ditech runs up to about 8,000 rpm and surprisingly, un restricted to about 10,000 which is good but I think about their limit. A single injector also limits things to 10,000 RPM or less. Simply because an injector small enough to allow good low speed tuning becomes to small to get things done in the limited "Time" available at higher RPM. A really well tuned B port injected or carburetor-ed 50 should run 15,000 RPM. 50% more RPM 50% more power possibility.

Currently my carburetor 50 only manages 12,000 RPM ( a better pipe might improve that). My B port EFI 110cc engine with the right fueling and ignition curve can run to 14,000 rpm which is a truly frightening experience. When I am standing beside it on the dyno at full noise I am acutely aware its con-rod comes from an old RD400.

[jfn2]

Thank you Neels:
Does this mean that a it is better to have a pin ground electrode rather then a ground electrode with a small hole drilled into its' center? Did the thesis say what the pin length should be?

[Wos]

Thank you Neels:
Does this mean that a it is better to have a pin ground electrode rather then a ground electrode with a small hole drilled into its' center? Did the thesis say what the pin length should be?

There are double iridium on the marked...with pin of iridium on the mass electrode ...or from beru ...with embedded iridium in the mass electrode. ..

Advantage should be higher livetime with more constant gap

[Vannik]

Thank you Neels:
Does this mean that a it is better to have a pin ground electrode rather then a ground electrode with a small hole drilled into its' center? Did the thesis say what the pin length should be?

I must still work my way through the thesis, its name is in the name of the picture, do a search and download it.

[katinas]

http://autosign.ps/brand-item/ngk-spark-plugs/ Interesting Cross slit type for rotary engine

[katinas]

I think it would benefit from steep angles on header and diffuser.

.

The easiest way would be to adapt two radically different existing race pipes from 50/65 cc, just correct header length for 6000- 10000 rpm. and see reactions.
As air is little easier to catch up to exhaust than mix, maybe more shallow angle is needed for front part of the pipe and steeper baffle. But maybe I am wrong.

With direct intake to transfers tests, simultaneously tried four different exhaust pipes.
Honda Rs copy (stainless 0.8 mm 121mm belly),
Aprilia Rsw simplifier copy (stainless 0.8 mm 128 mm belly),
Sugaya (specifically developed for this engine cylinder port dimensions, steel 0.8 mm 105 mm belly and longest)
BMB kart (steel 1mm 121 mm belly)
BMB kart modified (steel 1mm with baffle from stainless 1 mm 121 mm belly)

Honda and Aprilia both works in the good way, difference is just that Honda pipe always has sharper character from 10500 to 11500 rpm., but stops little earlier than Aprilia. Until 8000 rpm Aprilia pipe feels little stronger and fells more linear through rev range on this reed type engine.
But they both works very well and for this engine, after so many back to back tests still can't say which is more appropriate. Same was with RGV 250 engine, modified to 1 cylinder . Aprilia and Honda pipes was winners overall.

With BMB pipe engine revs highest, until 15000 rpm, but max power is lower than with Aprilia and Honda. Baffle is the same like on Honda, and whole pipe is more straight and accurate welded. Tried to extend header with 22 mm and 44 mm insert. With 22 mm engine stops at 13800 rpm, with 44 mm at 12500 rpm, but in both case max power was again lower than with 0,8 mm stainless Honda and Aprilia. is the barrier, the rise and fall time of the temperature is longer for BMB 1 mm steel , but maybe barrier is different oscillation amplitude of 0,8 mm sheet. On the second BMB pipe I will try to do baffle from 0.8 mm stainless.

[wobbly]

The kart pipes with the perforated reverse cone are specifically designed not to generate peak power , but rev like hell , with a very flat torque curve - as you discovered.
Lengthening the header will lower the peak rpm , but then the pipe proportions will be wrong , and anyway it still wont make any better peak power.
The only reason to use this design would be if you had a 4 speed gearbox , or no gears at all , like the karts the pipe design came from.

[katinas]

Thank you Wob.
I expected such a reaction from BMB pipe with a perforated part. So decide to cut rear perforated cone with outer cylindrical part and made usual rear cone from 1 mm stainless, with expectation to lose the bottom, but increase the top power.
Results, lower bottom and only just a little better top.
I have another, the same BMB pipe, so this time I will try to make thinner 0.8 mm rear cone see if there will be a difference.

Add dyno with exhaust pipes. BMB is modified, with usual rear cone.

[jonny quest]

Do you have the tuned lengths of the pipes Katrina's?

I enjoy reading your posts. Are you retired, and just enjoy playing with your toys? Or do you just not sleep?

[wobbly]

The best sparkplug for a racing 2T engine is the NGK R7376 - or the exact same plug with a short ceramic body designed for the RS125/250 from HRC - but you pay more for the cap than the plug itself.
Thats a R7282 ( A - being the longer thread version for use with a deto ring sensor ).
This was determined by a very detailed dyno session comparing many 10 range plugs all at one time.
The worst was a BR10EGV , next was the Denso version as was the later part number from Honda , then the best was R7376/R7282, same same.
All were resistor plugs , as my dyno goes spastic without them , as do the digital ECUs used on racebikes.

These NGK race plugs have a very small Irridium center electrode , and a fine wire Platinum ground ( mass , as I see others using ) electrode.
They are expensive due to the very small batch numbers , plus the special nose ceramic , special resistor element , and the fine wire mass electrode is laser welded.
Never , ever , had one fail .
The power difference best to worst , was 0.75 to 1.5 Hp - with the Denso almost exactly in the middle.

Frits , your Devil impersonation is well noted , but as NGK and Brisk plugs with huge sized ground electrodes are already confirmed as legal , having the nose flush with the chamber and then a small upstand
with the Platinum wire hanging off that , would be an easy argument to win in any Tech situation.

Machining the R7282A is easy to do with a rotating chuck 4th axis CNC , so I am having some done now.

[andreas]

Thank you Wob.
I expected such a reaction from BMB pipe with a perforated part. So decide to cut rear perforated cone with outer cylindrical part and made usual rear cone from 1 mm stainless, with expectation to lose the bottom, but increase the top power.
Results, lower bottom and only just a little better top.
I have another, the same BMB pipe, so this time I will try to make thinner 0.8 mm rear cone see if there will be a difference.

Add dyno with exhaust pipes. BMB is modified, with usual rear cone.

Your modified BMB pipe seems to be shorter than the rs- possibly 30mm? That is causing the power loss, not the thicker metal.

[jfn2]

That darn Wobbly, wouldn't you know he would name the exact plug that I'm using as the worst one of the lot. Right before I go on the dyno. Oh well!:wacko:
Thanks Wobbly. Does anyone have a part number for the cap?

[katinas]

Sugaya pipe length, from piston skirt to the end of rear cone (connection with tailpipe), about 900 mm
Honda Rs copy about 815- 820 mm ( needed to check again)
Modified BMB about 45 mm shorter than Rs.

Andreas, yes modified BMB pipe is about 45 mm shorter than Honda Rs (mainly at the header) and the engine response is not unexpected. Unexpected was that when BMB length was equalized to Rs (with a 44 mm length header insert), the BMB stopped at 12500 rpm and again with lower power and nearly 1500 rpm less than RS.
This is why I want to try 0,8 mm thick baffle and compare two identical BMB pipes, just one with 1 mm, other with 0,8 mm thick rear cone, without any header inserts.

Jonny, don't know why but at the moment I feel, that untested 2t ideas leave like painful wounds. That's why you always want to finish all the monetary works as soon as possible in order to get back to 2t things. I think most of the members of this great forum feel similar.
I am still thinking that piston ported intake, with staggered side intake windows and some accommodation from inside reed valve directly to A at ex side must be tried. This eliminate big reed cage housing. Simplicity, without any additional moving parts and compactness is still biggest advantage of 2t. If only we weren't limited in time .......

Ngk cap for short plug TRS 1225, Add photos of Honda RSW 250 A kit generator, similar to NSR 500 pre 1992 big bang 292-68

[jfn2]

Thank you Katinas.

[andreas]

Katinas, yes that is strange.

[husaberg]

Add photos of Honda RSW 250 A kit generator, similar to NSR 500 pre 1992 big bang 292-68

Almost a Japanese Krober.

[WilDun]

Two questions :
Has bucket racing resumed since Covid?
Where does Bucket Racing happen in Auckland these days since Mt Wellington was confiscated?

[F5 Dave]

1. yes. In the civilised areas.
And
2. It doesn't.
I posted a while back news article

[WilDun]

1. yes. In the civilised areas.
And
2. It doesn't.
I posted a while back news article

And now a question I had meant to ask previously, but stopped myself asking (in the interest of national unity amongst strokers,) why are there so many Wellingtonians and Cantrabians in this neck of the woods? is it the lack of 2 strokes here? or does something else bring them here? :msn-wink:

[crbbt]

with getting the spark plug to protrude further into the chamber,

couldn't the cylinder head be machined down where the spark plug washer meets the head rather than machine the plug itself?
where the rules permit :laugh:

[wobbly]

Machining the head sealing face to drop the plug into the chamber , as I see it , only does half the job - that is the spark gap is closer to the chamber center , but that gap isnt exposed any more than " stock ".
The R7376 type plugs with the Platinum ground electrode are very " shrouded " by the threaded body end in this respect , so using the longer body and machining off an annular ring does a very good
job of exposing the ionising gap to the surrounding A/F mixture.
But I believe the real issue with dropping in the plug will be that you end up with a bunch of exposed threads , that are not surrounded by the head alloy taking away heat.
This problem was addressed years ago by NGK with their race plugs , they had about 3mm of the threads removed , and i remember seeing a bulletin by them saying the plug body should be intruding
1.5mm into the chamber.
But all this is conjecture , in my case the rules dont allow the body to intrude at all, threaded or not , so I hope the machined body idea is one of the few free lunches I am allowed.

[crbbt]

whoops I thought the machine work was only happening to the bottom side of the should under the spark plug hex

[jfn2]

Has anyone tried this spark plug? NGK 7282-10 2000346528

[katinas]

Racing plugs for 2t with 14 mm thread, 19 long. Like Wob said, all is far better than, say, semi-racing types, not only because of ground platinum tip, but different ceramic. They are very reliable.

NGK three on the edge of their list (not adjustable gap and all resistor type)
R6205 -platinum/platinum, short ceramic 15 mm, TRS-1225 plug cap, (R6205A-22 mm long) 16 mm hex
R7282 -iridium/platinum ground, short ceramic 15 mm, TRS-1225 plug cap, (R7282A- 22 mm long) 16 mm hex
R7376- iridium/platinum ground, usual long ceramic 38mm, std. plug cap, 21 mm hex (R7436 - 16 mm hex and smaller diameter of long ceramic, for smaller eye plug cap)

Denso all iridium/platinum ground (adjustable gap)
IAE01- short ceramic 15 mm, TRS-1225 plug cap, 16 mm hex
IA01- short ceramic 15 mm, TRS-1225 plug cap (22 mm long) 16 mm hex
IW01- usual long ceramic 38 mm, std. plug cap, 21 mm hex
IW06- usual long ceramic 38 mm, std. plug cap, (plug without resistor) 21 mm hex

Champion (not adjustable gap and without resistor)
N721- platinum/platinum, semi short ceramic - 26 mm long, 21 mm hex

[wobbly]

The 7282 short or long thread is the same as 7376 in its construction , just with a short body and a stupid price for it and the cap.
In testing they performed identically.

[lodgernz]

Two questions :
Has bucket racing resumed since Covid?
Where does Bucket Racing happen in Auckland these days since Mt Wellington was confiscated?

As Dave said, bucket racing has resumed in Wellington, New Plymouth and Christchurch.
The Aucklanders raced at Hampton Downs Club Track last Sunday, and will be at Tokoroa next month.
Those two venues are the closest to Auckland now, and they may use Edgecumbe as well.
Once we are racing electric buckets, we will have the possibility of several other venues that we have lost through noise complaints from people with no lives.

[190mech]

Maybe moving back to parking lots,using electric mobility scooters..WOW!that sounds exciting!!:bash:

[Pursang]

Maybe moving back to parking lots,using electric mobility scooters..WOW!that sounds exciting!!:bash:

It's already a 'Thing'! :facepalm:
.
346531

[WilDun]

As Dave said, bucket racing has resumed in Wellington, New Plymouth and Christchurch.
The Aucklanders raced at Hampton Downs Club Track last Sunday, and will be at Tokoroa next month.
Those two venues are the closest to Auckland now, and they may use Edgecumbe as well.
Once we are racing electric buckets, we will have the possibility of several other venues that we have lost through noise complaints from people with no lives.

These people are not interested in bikes/buckets ..... or birds having a life either - they are prepared to cut down the trees to silence them! (the birds, not the trees!).
They would also object to the whine of electric motors if still in Auckland!
Hampton Downs / Mercer might suit the guys from Hamilton as well - quite a way out (from both places) but ideal area really for motorsport.
I'm surprised that Pukekohe didn't look ahead (- look at Bathurst!).

PURSANG
I should be doing that "facepalm" thing! - I have just sold two mobility scooters! (which I no longer need) - if you had told me about this earlier, I'd have been in! - (only because I can no longer throw a leg over a bike of course!).

[Flettner]

It's already a 'Thing'! :facepalm:
.
346531

And we already know how this will end. Would almost be worth watching, as the engines ( sorry, motors ) get ever more powerful.

[Muhr]

Hey all hope it's good with everyone in these covid times!
I have started to look at inconel exhaust. we have made 2 systems from the same file one in 0.5 inconel and one in 1mm steel. When we dyno 1mm exhaust, we ended up with an exhaust temp of 645 C. Then switched to the 0.5 system, we passed 690 C after half a pull and then cut the run. Then started tinkering with both jetting and stinger diameter but feel that it takes far too much to bring down the exhaust temperature. My question now is if anyone has encountered something similar and if one can accept a significantly higher exhaust temp (above 700C) without ending up with a hole in the piston, that the temp increase is isolated to exhaust?:confused:
Unfortunately, I cant blow up an engine in the next few weeks, in an attempt to find out.

[koenich]

This is only partially related to Inconel IMO. two factors come into play...

main factor for your observation is the thermal mass of your 0,5 mm pipe is lower than the one of the 1 mm variant. it's up to temp much faster and doesn't pull as much energy from the exhaust gas as the thicker variant. the 1 mm pipe on the other hand will need more energy to heat up, therefore the exhaust gas is cooler.

the thermal conductivity of Inconel is very similar to stainless steel (1.4301 for eg), but much lower compared to mild steel. means it doesn't transport as much heat to the environment as an mild steel one also increasing exhaust gas temp.

I'm curious why you used Inconel? The only advantage I see is yield strength at really high temperatures (> 1000 °C), which is not necessary for our application.

[Muhr]

This is only partially related to Inconel IMO. two factors come into play...

main factor for your observation is the thermal mass of your 0,5 mm pipe is lower than the one of the 1 mm variant. it's up to temp much faster and doesn't pull as much energy from the exhaust gas as the thicker variant. the 1 mm pipe on the other hand will need more energy to heat up, therefore the exhaust gas is cooler.

the thermal conductivity of Inconel is very similar to stainless steel (1.4301 for eg), but much lower compared to mild steel. means it doesn't transport as much heat to the environment as an mild steel one also increasing exhaust gas temp.

I'm curious why you used Inconel? The only advantage I see is yield strength at really high temperatures (> 1000 °C), which is not necessary for our application.

Hi thanks koenich the reason is just like you say lower mass which is the hope should be able to lead to a faster recovery in exhaust temp after longer off throttle. What I did not expect, however, was the significantly higher exhaust temperature.

[Frits Overmars]

This is only partially related to Inconel IMO. two factors come into play...

main factor for your observation is the thermal mass of your 0,5 mm pipe is lower than the one of the 1 mm variant. it's up to temp much faster and doesn't pull as much energy from the exhaust gas as the thicker variant. the 1 mm pipe on the other hand will need more energy to heat up, therefore the exhaust gas is cooler.
the thermal conductivity of Inconel is very similar to stainless steel (1.4301 for eg), but much lower compared to mild steel. means it doesn't transport as much heat to the environment as an mild steel one also increasing exhaust gas temp. Here is a graph in addition to Koenichs explanation, showing the results of three exhaust pipes with identical dimensions, all tested on the same engine with the same settings on the same day in the same atmospheric conditions.
346552

[wobbly]

Having a pipe made in Inconel wouuld have almost identical results as doing it in Titanium ie the wall temp would be significantly higher than one done in Mild Steel.
Add into that you have 1/2 the wall thickness , again increasing the temp of the gas by not removing energy to heat up the material.
If the original pipe was matched perfectly to the engine , then an Inconel or Ti pipe will need redesigning to suit the higher gas temp.
You are reading EGT , that is the temp of the gas in the header pipe - if 650 was fine before , then 700 will be fine now as there is no extra thermal load directly into the piston.
But as I said above , the higher egt number will automatically increase the local wave speed thru the gas molecules in the pipe .
This will either give you a ton of overev power at the expense of front side , maybe a good thing if thats what is needed , but if not then the design needs attention.
Rejetting to lower the egt means you are using fuel to cool the pipe , not using fuel to make Hp , thus compromising the ideal bsfc numbers - doomed to failure.

[marsheng]

I've done a search but not found much on Ignitech faults.

A Suzuki GT250 race bike with a battery, switch, inductive pickup coils, 12 HT coils, nothing else. After 10 or so dyno runs, stopped communication with PC. Ignitech fried.
Replaced with new Ignitech, programmed it, 5 or so runs later, box fried again.

I have done this conversion on another bike some time back with pit bike coils and it worked fine. Changed the 12v coils to pit bike ones, added a few more earth wires, programmed a new unit, 5 or so runs later, box fried again. Turn on the ignition and it sparks (both plugs) at about 800 RPM without the motor even turning.

I'm running out of units and thoughts.

Anyone have an idea on what is wrong ?

[marsheng]

Hey all hope it's good with everyone in these covid times!
I have started to look at inconel exhaust. we have made 2 systems from the same file one in 0.5 inconel and one in 1mm steel. When we dyno 1mm exhaust, we ended up with an exhaust temp of 645 C. Then switched to the 0.5 system, we passed 690 C after half a pull and then cut the run. Then started tinkering with both jetting and stinger diameter but feel that it takes far too much to bring down the exhaust temperature. My question now is if anyone has encountered something similar and if one can accept a significantly higher exhaust temp (above 700C) without ending up with a hole in the piston.
If you are going to ask this question, you need to add, and using a 0.5 mm probe. The piston temp remains the same with 1 and 0.5 mm probes, just the 0.5 reads 45 deg higher.

The next thing is, how long are the runs, short run, the piston doesn't have time to heat and melt, long runs, now you could have a problem.

[koenich]

Hi thanks koenich the reason is just like you say lower mass which is the hope should be able to lead to a faster recovery in exhaust temp after longer off throttle. What I did not expect, however, was the significantly higher exhaust temperature.
makes sense. the transient response of the pipes is very similar as you can see in the inclination of the logged temps, I would have expected the thinner one would react faster. likely the 1 mm variant contains more energy due to the higher thermal mass, which adds energy to the exhaust gas off throttle. transient behavior is always hard to judge up front.

It's important to use the same thicknesses of thermo couples for both tests, a thinner one will react faster and lead to wrong conclusions.

Side note - I do car manifolds/exhausts for a living at a Tier 1 supplier, and have some inside about material choice/properties/behavior. Personally I'd stay away from Inconel, it's only necessary for really high temp applications like supercar manifolds to maintain some sort of strength on full load. If the welding process and penetration are not absolutely perfect you get all kind of funny failures (cold cracks, hardened weld seams,...). Just use some 1.4301, very similar thermal properties and fraction of the price.

[JanBros]

I have done this conversion on another bike some time back with pit bike coils and it worked fine. Changed the 12v coils to pit bike ones

are the pitbike coils from an AC or a DC ignition ? if from AC and you use them in a DC-system like your ignitech, the primary circuit is basicly in short-circuit because the primary resistance is too low.

[wobbly]

The primary resistance of the coils that work best with DC CDI Ignitech should be as low as possible - 0.3Ohm.
The only 3 things that kills Ignitechs are - One ,continuous over voltage condition from the regulator not working properly.There is a voltage crowbar circuit that shuts the box down over 15V
but if you keep on doing it , they fail.
Two , not using a 5K resistor plug , AND a 5K resistor plug cap.This fries the com circuit due to EMI contamination.
Three , same effect really , but if the input wires , that is the trigger or power or PV sense circuit wires are not physically seperated enough from the output ( coil ) wires , both primary and secondary , the EMI
noise contamination runs back up these inputs and fries the ECU computer.
Good luck with sending tham back to be fixed , I sent 4 failed units to them 3 years ago , and even though I had sold over 100 units for them , suddenly they refuse to even acknowledge I exist. Arseholes
of the first order.

[Ns1Montesa]

Hi everybody,

this is my first post in this forum. I want to say thank you to all you people sharing their knowledge, ideas, experiences and pictures about two strokes in this thread. I would say this is the best place to expand your knowledge about two stroke engines in the WWW.

I am from Germany, so please excuse my bad english. I hope it is good enough to ask some questions and participating in this great thread.

At the moment I am working on a Honda NS1 Engine. It is a 75cc single engine, reedvalve in cast iron water cooled cylinder. Should be the same as mbx80 and close to the air cooled honda engines like mtx80, mb8, mb100 and so on.

I do not race this bike/engine. I just want to know how much reliable HP I can get out of it. It is just for fun.

At the moment I am a little bit stuck at around 16hp at the wheel. My thinking was that the inlet is the most restricting part in the engine. So I decided to drill some Boyesen ports from reed case to B transfers to get more port area linked directly to the crank case.
Today I tested it on the Dyno and I was very disappointed. I did not change anything, just added the Boyesens and the power dropped about 0.5HP. After setting the carb leaner, from 135 to 125 mainjet the peak power was close to the old power, but the low end power is still worse than before.
Is it normal that I need to rejet the carb after adding Boyesen ports? And what is the reason for the power loss in low and mid range? Is it because I increased the volume of the crank case or are the ports disturbing the flow of the B transfers?

The engine is running with Ignitec, PWK28, homebuild expansion chamber, CR around 12,5 to 1, EX duration 192° Transfers 128°


Would be awesome if somebody knows how to solve this issue or can explaine why boyesens are not working for me. And If someone knows more about getting power out of these honda engines, please let me know:cool:

cheers

josh

[husaberg]

Hi everybody,

this is my first post in this forum. I want to say thank you to all you people sharing their knowledge, ideas, experiences and pictures about two strokes in this thread. I would say this is the best place to expand your knowledge about two stroke engines in the WWW.

I am from Germany, so please excuse my bad english. I hope it is good enough to ask some questions and participating in this great thread.

At the moment I am working on a Honda NS1 Engine. It is a 75cc single engine, reedvalve in cast iron water cooled cylinder. Should be the same as mbx80 and close to the air cooled honda engines like mtx80, mb8, mb100 and so on.

I do not race this bike/engine. I just want to know how much reliable HP I can get out of it. It is just for fun.

At the moment I am a little bit stuck at around 16hp at the wheel. My thinking was that the inlet is the most restricting part in the engine. So I decided to drill some Boyesen ports from reed case to B transfers to get more port area linked directly to the crank case.
Today I tested it on the Dyno and I was very disappointed. I did not change anything, just added the Boyesens and the power dropped about 0.5HP. After setting the carb leaner, from 135 to 125 mainjet the peak power was close to the old power, but the low end power is still worse than before.
Is it normal that I need to rejet the carb after adding Boyesen ports? And what is the reason for the power loss in low and mid range? Is it because I increased the volume of the crank case or are the ports disturbing the flow of the B transfers?

The engine is running with Ignitec, PWK28, homebuild expansion chamber, CR around 12,5 to 1, EX duration 192° Transfers 128°


Would be awesome if somebody knows how to solve this issue or can explaine why boyesens are not working for me. And If someone knows more about getting power out of these honda engines, please let me know:cool:

cheers

josh

Hi Josh send a picture of the reed valve and intake port

[wobbly]

Two conflicting issues going on there.
First is that ,yes , the hole thru from the inlet into the B port entry is affecting the flow regime into the duct.
Second , Boyesen ports were developed as a "quick fix " when cylinder mounted intake flow became the restricting bottleneck in an engines tune.
When this happens the increase in bulk flow , due to more unrestricted intake area , has a much greater positive effect on the Delivery Ratio than it has a negative effect on the B port duct entry.
It would seem in your case that the intake bulk flow capability isnt the bottleneck you thought it was.
You may find that the intake capability doesnt become the weak link until you approach , im guessing ,say 20 Hp.
It has been seen many times with lower Hp engine setups that the so called " Power Porting " approach ie no holes in the piston that then forces higher reed box pressure /flow to enter the cylinder via the boost port
makes more power.
But this quickly has reduced positive effect as the need for outright bulk flow , to support much higher power , takes precedence.

[F5 Dave]

Time to break out the devcon.

[Ns1Montesa]

Two conflicting issues going on there.
First is that ,yes , the hole thru from the inlet into the B port entry is affecting the flow regime into the duct.
Second , Boyesen ports were developed as a "quick fix " when cylinder mounted intake flow became the restricting bottleneck in an engines tune.
When this happens the increase in bulk flow , due to more unrestricted intake area , has a much greater positive effect on the Delivery Ratio than it has a negative effect on the B port duct entry.
It would seem in your case that the intake bulk flow capability isnt the bottleneck you thought it was.
You may find that the intake capability doesnt become the weak link until you approach , im guessing ,say 20 Hp.
It has been seen many times with lower Hp engine setups that the so called " Power Porting " approach ie no holes in the piston that then forces higher reed box pressure /flow to enter the cylinder via the boost port
makes more power.
But this quickly has reduced positive effect as the need for outright bulk flow , to support much higher power , takes precedence.

Thanks for your reply wobbly.

Bad news, but there is something positive about it. Now I know the stock intake port should be good enough for more power.

Is there any good method to determine where the bottleneck of an engine is? I tested various exhausts, but none of them gave more than around 10nm of torque. Changed the carb from 24mm to 28mm. That only made the powerband broader and gave very little increase in peak power. Tested a Vforce3 reed from a KTM sx50, made aboslultely no difference.
How much can I expect from pointing the transfers more upwards? Untouched they are close to 90 degree in relation to the bore axis.



Hi Josh send a picture of the reed valve and intake port

Here is the reed I am using and the Intake. The reeds are the size of the Minarelli AM6 ones.

Cheers

Josh

[husaberg]

Here is the reed I am using and the Intake. The reeds are the size of the Minarelli AM6 ones.

Cheers

Josh

Wow,Far better than a H100 or MB5.
The CR85 has a slightly bigger looking one with single reeds and a stuffer. its a bolt on with maybe only the cavity requiring work if the MB engiges are anything to go by.
346581346582

[Frits Overmars]

Hi everybody, this is my first post in this forum. I want to say thank you to all you people sharing their knowledge, ideas, experiences and pictures about two strokes in this thread. I would say this is the best place to expand your knowledge about two stroke engines in the WWW. I am from Germany, so please excuse my bad english.Hi Josh, herzlich willkommen. I wish my German was as good as your English. But as I keep saying, German is a much richer language than English: if offers far more opportunities to make mistakes :whistle:


Is there any good method to determine where the bottleneck of an engine is? I tested various exhausts, but none of them gave more than around 10nm of torque. Changed the carb from 24mm to 28mm. That only made the powerband broader and gave very little increase in peak power. Tested a Vforce3 reed from a KTM sx50, made aboslultely no difference.You can compare a two-stroke engine with a 10-digit combination lock. Even if you get nine out of those ten digits correct, you won't know because nothing happens. Only when you have all ten correct, you may sing and dance.
How do you determine the bottleneck? Work, lots of work. And experience, lots of experience.
346584


How much can I expect from pointing the transfers more upwards? Untouched they are close to 90 degree in relation to the bore axis.Raising the axial angle of the A-ports to about 25° can give a nice improvement. Better leave the axial angles of the B- and C-ports alone for the time being.
If you can find the time, visit one of the German SimsonGP races; free admittance if you give them my regards (and also if you don't :D).
Several riders there use your type of engine, and a good one produces about 22 hp, even with the cast-iron cylinder.

[Condyn]

First:
I am trying to source a longer connecting rod for an engine to get the r/s ratio to 2:1. The only rods I have access to that will meet this requirement are 3mm more narrow on the big end. I assume there is a slight strength compromise. Is it ok to source thicker thrust washers for this scenario? Having trouble finding them too, but might be easier than the rods I am after.

Second:
The engine I am working on/designing is a piston port with only A and B transfers. I have been thinking about adding a boost port from the intake duct. Is there a proper way to do this on a piston port? Add to the main intake window like a boost port on an old cylinder reed engine, or tap back into the port to leave a horizontal bridge between the two? The ring end gap is offset to one side and will definitely catch the proposed window and horizontal bridge if I do that. I understand the pipe does the pulling, but would something like this even work?

[katinas]

Hi Josh, like Husa said, it would be interesting to see more photos of the cylinder with all ports and piston.

Looks like original cylinder designed to concentrate intake flow mass directly to crankcase, through main intake windows/piston skirt together with another port arranged downward to crankcase, so there is no high flow through this additional holes, from piston movement (just from on-pipe) and its even better for back flow to reed space.

Rising piston side cutouts as high as piston construction allows, helps to rise flow velocity through this boyesens, as A and B opens longer at TDC and send stronger pulse to reed space, directly through this holes. And together with some original intake flow restrictions (base gasket with smaller cuts for down side intake) or piston without holes, mix velocity through boyesens could rise even more.
We noticed, modifications that concentrated intake mass flow more to transfers, require leaner mix.
Add photo of kit version for NSR/NS/mbx, and pistons, that could sing in a duet with the big boyesens, but not with piston ported or rotary valve type engines.

[peewee]

First:
I am trying to source a longer connecting rod for an engine to get the r/s ratio to 2:1. The only rods I have access to that will meet this requirement are 3mm more narrow on the big end. I assume there is a slight strength compromise. Is it ok to source thicker thrust washers for this scenario? Having trouble finding them too, but might be easier than the rods I am after.

Second:
The engine I am working on/designing is a piston port with only A and B transfers. I have been thinking about adding a boost port from the intake duct. Is there a proper way to do this on a piston port? Add to the main intake window like a boost port on an old cylinder reed engine, or tap back into the port to leave a horizontal bridge between the two? The ring end gap is offset to one side and will definitely catch the proposed window and horizontal bridge if I do that. I understand the pipe does the pulling, but would something like this even work?

if something doesnt fit you have to make your own parts. many pages back i showed some small end thrust washers i made. seems like was 4130 1mm thick

[yatasaki]

First:
I am trying to source a longer connecting rod for an engine to get the r/s ratio to 2:1. The only rods I have access to that will meet this requirement are 3mm more narrow on the big end. I assume there is a slight strength compromise. Is it ok to source thicker thrust washers for this scenario? Having trouble finding them too, but might be easier than the rods I am after.

Second:
The engine I am working on/designing is a piston port with only A and B transfers. I have been thinking about adding a boost port from the intake duct. Is there a proper way to do this on a piston port? Add to the main intake window like a boost port on an old cylinder reed engine, or tap back into the port to leave a horizontal bridge between the two? The ring end gap is offset to one side and will definitely catch the proposed window and horizontal bridge if I do that. I understand the pipe does the pulling, but would something like this even work?
You mean from or through intake port? If through you can connect crankcase with pipe which will pass through the middle of the inlet or with two pipes which will pass through corners of the inlet port. It depends of the configuration of the cylinder, studs and crankcase base but usually single center pipe is better option cause of bigger pipe cross section and inlet side walls are formed to follow cross section of the inlet port with transfer pipe in center.
CZ bikes used to have this kind of arrangement.

[wobbly]

Simple answer to the bottleneck question , is you need to use a port calculator to ascertain the relationship between the intake/transfer/blowdown STA numbers.
The engine will always hit a wall as soon as one of these is out of sync with the other two.
You now know its not the intake that prevented better ( if they actually were better ) pipes from working as intended.

A perfect example of this was an LC350 I analysed during lockdown.
It had been ported by a well known English "name " tuner , and he had actually done a very nice job of giving the staggered transfers the capability of 52 Hp/cylinder , but sadly the Blowdown STA was down at 34 Hp.
This was why several sets of pipes made no difference at all - and the worst/skinnyest most horribly made pipes worked OK.
Banshee VF4 didnt work, 34mm carbs didnt work , more com didnt work , long rods didnt work etc etc.

[F5 Dave]

First:
I am trying to source a longer connecting rod for an engine to get the r/s ratio to 2:1. The only rods I have access to that will meet this requirement are 3mm more narrow on the big end. I assume there is a slight strength compromise. Is it ok to source thicker thrust washers for this scenario? Having trouble finding them too, but might be easier than the rods I am after.

Second:
The engine I am working on/designing is a piston port with only A and B transfers. I have been thinking about adding a boost port from the intake duct. Is there a proper way to do this on a piston port? Add to the main intake window like a boost port on an old cylinder reed engine, or tap back into the port to leave a horizontal bridge between the two? The ring end gap is offset to one side and will definitely catch the proposed window and horizontal bridge if I do that. I understand the pipe does the pulling, but would something like this even work?

So first question, can you use the matching pistons to the new rods? I found out the hard way when my new piston was a few mm wider. The std piston was tapered at the top to retain the bearing and I never spotted it being too obsessed with moving ring peg, etc. OK i was a Klutz.
I used some hardened thrust washers which worked well but needed replacing every year racing.


2nd, and most obvious, can you fit a reed cage? Then you can fashion a straight std boost port in conventional style above reed cavity.

I used to cut the back 20mm off a scrap barrel and tack each corner so its strong without warping things, dig out the cavity and devcon the gaps. That gives you matching reed and manifold to use.

Or if your case, and desire to make things difficult for yourself, add the reed to the crankcases. Done that twice.

[husaberg]

First:
I am trying to source a longer connecting rod for an engine to get the r/s ratio to 2:1. The only rods I have access to that will meet this requirement are 3mm more narrow on the big end. I assume there is a slight strength compromise. Is it ok to source thicker thrust washers for this scenario? Having trouble finding them too, but might be easier than the rods I am after.


what size length and widths are you wanting?

[andreas]

Hi everybody,

this is my first post in this forum. I want to say thank you to all you people sharing their knowledge, ideas, experiences and pictures about two strokes in this thread. I would say this is the best place to expand your knowledge about two stroke engines in the WWW.

I am from Germany, so please excuse my bad english. I hope it is good enough to ask some questions and participating in this great thread.

At the moment I am working on a Honda NS1 Engine. It is a 75cc single engine, reedvalve in cast iron water cooled cylinder. Should be the same as mbx80 and close to the air cooled honda engines like mtx80, mb8, mb100 and so on.

I do not race this bike/engine. I just want to know how much reliable HP I can get out of it. It is just for fun.

At the moment I am a little bit stuck at around 16hp at the wheel. My thinking was that the inlet is the most restricting part in the engine. So I decided to drill some Boyesen ports from reed case to B transfers to get more port area linked directly to the crank case.
Today I tested it on the Dyno and I was very disappointed. I did not change anything, just added the Boyesens and the power dropped about 0.5HP. After setting the carb leaner, from 135 to 125 mainjet the peak power was close to the old power, but the low end power is still worse than before.
Is it normal that I need to rejet the carb after adding Boyesen ports? And what is the reason for the power loss in low and mid range? Is it because I increased the volume of the crank case or are the ports disturbing the flow of the B transfers?

The engine is running with Ignitec, PWK28, homebuild expansion chamber, CR around 12,5 to 1, EX duration 192° Transfers 128°


Would be awesome if somebody knows how to solve this issue or can explaine why boyesens are not working for me. And If someone knows more about getting power out of these honda engines, please let me know:cool:

cheers

josh

Although your engine has the long cylinder studs, it seems someone has managed to have aux ex-ports in it. Might be worth looking into.

[Condyn]

You mean from or through intake port? If through you can connect crankcase with pipe which will pass through the middle of the inlet or with two pipes which will pass through corners of the inlet port. It depends of the configuration of the cylinder, studs and crankcase base but usually single center pipe is better option cause of bigger pipe cross section and inlet side walls are formed to follow cross section of the inlet port with transfer pipe in center.
CZ bikes used to have this kind of arrangement.

From the intake

[Condyn]

So first question, can you use the matching pistons to the new rods? I found out the hard way when my new piston was a few mm wider. The std piston was tapered at the top to retain the bearing and I never spotted it being too obsessed with moving ring peg, etc. OK i was a Klutz.
I used some hardened thrust washers which worked well but needed replacing every year racing.


2nd, and most obvious, can you fit a reed cage? Then you can fashion a straight std boost port in conventional style above reed cavity.

I used to cut the back 20mm off a scrap barrel and tack each corner so its strong without warping things, dig out the cavity and devcon the gaps. That gives you matching reed and manifold to use.

Or if your case, and desire to make things difficult for yourself, add the reed to the crankcases. Done that twice.

This particular engine has to remain a piston port. I have quite a bit of devcon in this engine already. Any more would make me cringe.

I may have found thick washers but not certain they will work yet. Is it not advised to stack thrust washers on the big end bearings to make up for a more narrow rod?

[Condyn]

what size length and widths are you wanting?

Ideally:
C-C=120mm
Width both ends= 20mm
Big end bore= 31mm
Small end bore= 22 or 23mm both bearings avail

There is a rod that’s 17 wide on both ends that is readily available but would need to find oddball thrust washers. The bottom rod/bearing is offset on the pin to one side

[husaberg]

Ideally:
C-C=120mm
Width both ends= 20mm
Big end bore= 31mm
Small end bore= 22 or 23mm both bearings avail

There is a rod that’s 17 wide on both ends that is readily available but
need to find oddball thrust washers. The bottom rod/bearing is offset on the pin to one side

TS-250ER
B.E.BEARING DIA (mm)：Ａ 31.0
S.E.BEARING DIA (mm)：Ｂ 23.0
B.E.& S.E. PITCH (mm)：Ｃ 120.0
B.E.THICKNESS (mm)：Ｄ 19.8
S.E.THICKNESS （mm)：Ｅ 23.8
CRANK PIN DIA (mm)：Ｆ 25.0
CRANK PIN LENGTH (mm)：Ｇ 58.0
Ts250ER a little wider in the small end.


Dt250 5mm to long
MODEL
DT-250/YZ-250
B.E.BEARING DIA (mm)：Ａ 31.0
S.E.BEARING DIA (mm)：Ｂ 22.0
B.E.& S.E. PITCH (mm)：Ｃ 125.0
B.E.THICKNESS (mm)：Ｄ 20.0
S.E.THICKNESS （mm)：Ｅ 20.0
CRANK PIN DIA (mm)：Ｆ 25.0
CRANK PIN LENGTH (mm)：Ｇ 60.0

i will have a proper look tomorrow

[Condyn]

TS-250ER
B.E.BEARING DIA (mm)：Ａ 31.0
S.E.BEARING DIA (mm)：Ｂ 23.0
B.E.& S.E. PITCH (mm)：Ｃ 120.0
B.E.THICKNESS (mm)：Ｄ 19.8
S.E.THICKNESS （mm)：Ｅ 23.8
CRANK PIN DIA (mm)：Ｆ 25.0
CRANK PIN LENGTH (mm)：Ｇ 58.0
Ts250ER a little wider in the small end.


Dt250 5mm to long
MODEL
DT-250/YZ-250
B.E.BEARING DIA (mm)：Ａ 31.0
S.E.BEARING DIA (mm)：Ｂ 22.0
B.E.& S.E. PITCH (mm)：Ｃ 125.0
B.E.THICKNESS (mm)：Ｄ 20.0
S.E.THICKNESS （mm)：Ｅ 20.0
CRANK PIN DIA (mm)：Ｆ 25.0
CRANK PIN LENGTH (mm)：Ｇ 60.0

i will have a proper look tomorrow

I appreciate it. I don’t know if machining the rods width down is advised, but if that’s a possibility I would be willing to go that route.

[jonny quest]

I appreciate it. I don’t know if machining the rods width down is advised, but if that’s a possibility I would be willing to go that route.

You can narrow rods on a belt sander. Just do one side at a time and keep checking how square it is to original side. After you have half your intended width removed on the one side and it's still square to within .001", do the other side and keep that square.

Just be honest with yourself, this new rod from a performance engine, or heavier piston than what you have.... it's usually ok to take off some width.

You can also press your crank together a little more if you need to take up rod to cheek space. .5mm is a good gap. A bigger gap between cases and cheeks are usually preferred over what stock was

[WilDun]

You can narrow rods on a belt sander. ...........

Doesn't the removal of the outer hardened shell affect the strength? I tend to think it might! - but of course, if it works ........!

[Ns1Montesa]

Hi Josh, herzlich willkommen. I wish my German was as good as your English. But as I keep saying, German is a much richer language than English: if offers far more opportunities to make mistakes :whistle:

You can compare a two-stroke engine with a 10-digit combination lock. Even if you get nine out of those ten digits correct, you won't know because nothing happens. Only when you have all ten correct, you may sing and dance.
How do you determine the bottleneck? Work, lots of work. And experience, lots of experience.
346584

Raising the axial angle of the A-ports to about 25° can give a nice improvement. Better leave the axial angles of the B- and C-ports alone for the time being.
If you can find the time, visit one of the German SimsonGP races; free admittance if you give them my regards (and also if you don't :D).
Several riders there use your type of engine, and a good one produces about 22 hp, even with the cast-iron cylinder.

Hello Frits,

yes, the german language is difficult, sometimes even for native speaker:laugh:

Already thought about visiting the SimsonGP. Maybe I find the time for it. There are two events left for this years season.
22 Hp, thats a good number. Would be happy if I reach 20.

You are right about the bottleneck. There are too many variables in a two stroke engine to give a good answer to my silly question.



Hi Josh, like Husa said, it would be interesting to see more photos of the cylinder with all ports and piston.

Looks like original cylinder designed to concentrate intake flow mass directly to crankcase, through main intake windows/piston skirt together with another port arranged downward to crankcase, so there is no high flow through this additional holes, from piston movement (just from on-pipe) and its even better for back flow to reed space.

Rising piston side cutouts as high as piston construction allows, helps to rise flow velocity through this boyesens, as A and B opens longer at TDC and send stronger pulse to reed space, directly through this holes. And together with some original intake flow restrictions (base gasket with smaller cuts for down side intake) or piston without holes, mix velocity through boyesens could rise even more.
We noticed, modifications that concentrated intake mass flow more to transfers, require leaner mix.
Add photo of kit version for NSR/NS/mbx, and pistons, that could sing in a duet with the big boyesens, but not with piston ported or rotary valve type engines.


Keeping the transfers open for a longer time via piston cutouts to get some more sucktion to the boyesens is a smart idea. I will keep that in mind. But for now I will leave the piston untouched.



Simple answer to the bottleneck question , is you need to use a port calculator to ascertain the relationship between the intake/transfer/blowdown STA numbers.
The engine will always hit a wall as soon as one of these is out of sync with the other two.
You now know its not the intake that prevented better ( if they actually were better ) pipes from working as intended.

A perfect example of this was an LC350 I analysed during lockdown.
It had been ported by a well known English "name " tuner , and he had actually done a very nice job of giving the staggered transfers the capability of 52 Hp/cylinder , but sadly the Blowdown STA was down at 34 Hp.
This was why several sets of pipes made no difference at all - and the worst/skinnyest most horribly made pipes worked OK.
Banshee VF4 didnt work, 34mm carbs didnt work , more com didnt work , long rods didnt work etc etc.


Bigger/more holes are not always better. Thats what I learned from my boysen drilling mistake.
I will take the cylinder off, measure the ports, calculate the STAs and check if the transfers and the exhaust are capable of giving more power.


Although your engine has the long cylinder studs, it seems someone has managed to have aux ex-ports in it. Might be worth looking into.

hi andreas,

your picture shows the port map of the Italkit cylinder. Katinas picture shows a similar one. I think the only difference is the exhaust port.
The standard honda cylinder has got a bridged exhaust port.
The italkit cylinders are no longer produced and used ones are rare.

Katinas, I added a picture of the cylinder I am using(Honda). Portmap(sloppy one) and picture from the underside. Left is stock cylinder. Right is slightly modifyed. Only removed the sharp edges of the intake ports and transition from bore to transfers. Exhaust is widened a bit.


Thanks everybody

cheers

josh

[husaberg]

Doesn't the removal of the outer hardened shell affect the strength? I tend to think it might! - but of course, if it works ........!

Hi Will, The widths of the rods are the last things machined on the rods there is no hard skin remaining on this part of the rod that i have noticed.
On a belt sander they thin down like butter.

[katinas]

Josh, with additional boyesens, try to close crankcase intake port ( fully or partially, red line) , this is very easy to do with the base gasket. It was like, close the door when another opened.
Port map looks like really capable for 20hp.

[lodgernz]

Would be awesome if somebody knows how to solve this issue or can explaine why boyesens are not working for me. And If someone knows more about getting power out of these honda engines, please let me know:cool:
josh

Hi Josh. I believe that grinding away (i.e. raising) the separator between the A & B ports a few mm allows some of the charge coming through the Boyesen ports better access to the A port. Without this, only the B ports benefit from the Boyesen flow.
Also, there are a lot of sharp edges on the lower cylinder outer that can impede flow. If you look into the reed cavity you'll see that the incoming charge has a lot of disturbance from these sharp edges and corners. Easy to smooth these off.

Although you can't get any really nice after-market cylinders any more for these engines, you can get a 44mm stroke Italkit crank, and you can of course bore them up to 54mm. You might be able to find a Malossi 53mm cylinder, which are cast-iron but with quite nice transfers. The exhaust timing on these is mild, but as it is cast-iron, easy to improve.

And if you really want to spend some money, get a VHM head with insert. They work well.

After all that, it is really matching the pipe to the cylinder that will determine the power.

[Greg85]

Milling the spark plug puts the spark gap closer to the middle of the camber. It also promotes access of the mixture to the gap between the electrodes, helping it to replace the burned gases with stuff that still wants to burn. And it cools the plug.
346431

Speaking of tech rules: the above rule seems so simple; what could possibly go wrong? Well, I would claim that the mass electrode is part of the plug body, so this simple rule simply renders all present-day spark plugs illegal :devil2:.

Hello frits, wobbly,
then yes indeed with this type of spark plug the ignition and much better!! its even corrects the carburations a little more fat.
I tested a spark plug for ngk 105 for rotary engine rx7 a 21mm body, is indeed it works because you bring the spark plug close to the piston but is illegal in kz2.
However, I wondered at that time when Max Verstappen at the 2013 World Cup in France didn't have a short spark plug but a standard spark plug for the ngk br10 but apparently, I think it was beneficial for the carburettor set-up because this track on the Varennes allier is very complicated to find a good carburettor setting. jos Verstappen himself said in a kartmag interview that it was difficult for the carburettor set-up here.
franco drudi tm in any case does not use long spark plugs but short ones...
so he must have a good carburettor set-up for everyone because he never breaks an engine! I saw in a post at wobbly that franco runs with a bigger cylinder head volume of 13.6cc so I think it helps from a detonation point of view that this works at the 13.02cc limit.

346639346639346640346641

[Condyn]

Question regarding pipe wall temp and EngMod2t inputs.. I can’t afford to dyno test regularly so improvising is a necessity right now. We run cvt drive snowmobiles over here and I have devised a plan to test once we have snow. Since the engine rpm is influenced by the cvt system that uses a primary drive clutch and a secondary driven clutch. In order to determine when the engine is starting to get on the pipe I have manufactured this spacer (which I intend to replace with a safer quality unit) to stop the primary drive from closing completely. It limits how much the spring can close and is set so there is just enough belt pressure to move the machine. If I slowly roll into the run and ramp the rpms up my thought is that by watching the tachometer I will be able to tell when the engine begins to get on and then off the pipe. Also included is a photo of CHT thermocouples that I intend to fasten to the pipe wall at various places during this test. By facing a go-pro video camera at the gauges I effectively have a usable datalogger. I understand inner wall temp is used in the program, but could this method be accurately used?

[wobbly]

I have done exactly as you are proposing to do , this info was needed by Neels when he was implementing the wall temp varying with rpm option.
But I data logged the temp after doing several all gear runs , then 3 pulls in top gear averaged.
In all of the race engines I have modelled , produced a pipe , built it and dyno tested it , much the same wall temps work in testing as in the sim.
With the final header egt reaching 620*C every time, the average pipe wall temp starts at 325 under the pipe ( 8,000 for a KZ engine ) and reaches 425 at peak power ( 13500 for the KZ again ).
The problem with measuring the wall outer temp is that the header is hottest , but has a very small area comparred to the mid section temp.
The end of the rear cone ( about 1/3 up from the stinger ) is 1/2 way between those two temps , and that too is of much smaller surface area than the cooler mid section.
Those average numbers I found were worked backwards from the dyno result of existing pipes, and gave identical powerband shape and peak power rpm in the sim.

[Condyn]

Re wall temps *edited*
So you are saying that every race engine you have tested with 620° C EGT in the header, your prescribed wall temps of 325° and 425° have been spot on? I am a bit confused as to if your findings while performing the test I am proposing worked or if you ended up plugging numbers in until things lined up in the sim and dyno test? I guess my main question would be; if I install 4 outside wall thermocouples on the pipe in the proper places, will I end up with 325° start of powerband and 425° peak?

[wobbly]

Short answer is no , because it way difficult to calculate the average wall temps due to the temp/area problem , plus you are measuring outside.
As I have such a huge database of pipes and engines that have been thru the sim , build , dyno process , it was easy to check backwards from the dyno result to see what
average wall temps were being generated with my self impossed "tuning target " of 620*C in the header.
Some engines made best power at 650 in the header , but using a simple ratio increasing by 650/620 worked just as well.
In the case where using really good fuel ( 110 leaded ) allowed 680*C on track ( SKUSA ) the pipes designed for 620 simply reved to the moon , but this proved to be a huge tuning aid in that we could use
the gained rpm range to go faster on the same gear , or re gear it to gain off corner acceleration with identical terminal speed.

[flyincat]

Wobbly - thanks for sharing about the pipe temp. I'm still a little foggy on measurement locations for your average wall temp method. Do you measure outside wall temp at center section and at rear cone 1/3 up from stinger? Just two measurements? I assume your header measurement is an internal EGT and not used in the average?

Would it make any sense to put an open tip EGT into the pipe towards the end of the rear core or maybe even in the stinger? I'm thinking it would give you a one point snapshot of how hot the gases were after running the whole course of the pipe?

[pete376403]

Where you do your best thinking, a bit of inspiration:
https://www.facebook.com/172666339851420/videos/671403630379114/?t=3

[Condyn]

I will attempt to simplify. It is becoming evident that Neels and Wobbly have developed variables that work, so we do not need to measure up and down the pipe. Doing so without the proper equipment and technique would just add headaches. If the pipe was say 80mm diameter the entire way through, we could perhaps gather the temp data easily and accurately. But since the header is smaller than the center section and so on, it adds more math to the dynamics of what is already going on temp wise in the pipe. Lastly the number relies on inner wall temp and not outer wall temp. Wall temp and EGT are not one in the same. Wobbly knows what his target EGT was for every engine he has tested, (typically 620°) so they developed inputs (325° and 425°) for us to use. If the engine made better power at 650° you would use the simple math noted above to adjust your wall input variables. It is my best guess that the extra options were added to Data2t for completeness. If I am not understanding this I wish to be corrected.

[Frits Overmars]

As I have such a huge database of pipes and engines that have been thru the sim , build , dyno process , it was easy to check backwards from the dyno result to see what average wall temps were being generated with my self impossed "tuning target " of 620*C in the header.
Some engines made best power at 650 in the header , but using a simple ratio increasing by 650/620 worked just as well.Wob, the ratio in your example would be 650 / 620 = 1,048 . But wouldn't it be better to determine the ratio using absolute temperatures?
Then we would find (650 + 273) / (620 + 273) = 1,034.
Not much of a difference, I'll admit, but still a difference.

[TZ350]

.
Passed through Greymouth the other day and visited my favorite hardware shop.

346656 Loved the OHS Occupational Health and Safety sign.

346657 If only.

346653346654346655346658

Such an amazing example of early West Coast ingenuity. Absolutely love it.

Link to a previous visit and a lot more photos of other bikes and interesting things.
Work had me in Greymouth the last week.

[flyincat]

Wobbly knows what his target EGT was for every engine he has tested, (typically 620°) so they developed inputs (325° and 425°) for us to use. If the engine made better power at 650° you would use the simple math noted above to adjust your wall input variables. It is my best guess that the extra options were added to Data2t for completeness. If I am not understanding this I wish to be corrected.

Condyn, thanks for the reply. The reason I ask is because I believe the snowmobile application, especially drag racing, won't be using these wall temps. While you may see the 620-650C at the header EGT, I seem to get wildly unrealistic results using 425C at peak power. This gets back to my original inquiry of measurement points to create a temp profile for a very different application. I know Wob did some drag racing (Banshee?) work where pipe wall temps might be more comparable to snowmobile application.

[Condyn]

Condyn, thanks for the reply. The reason I ask is because I believe the snowmobile application, especially drag racing, won't be using these wall temps. While you may see the 620-650C at the header EGT, I seem to get wildly unrealistic results using 425C at peak power. This gets back to my original inquiry of measurement points to create a temp profile for a very different application. I know Wob did some drag racing (Banshee?) work where pipe wall temps might be more comparable to snowmobile application.

We almost need to take an engine that works very well at 425C with matching curves on both dyno and the sim, with the same egt in the header that we are using in our snowmobiles, measure the outer wall temp on that engine in many specific places, and measure the outer wall temp on our engines the same way. Maybe with the correct math we can then create a scale that makes the outer wall temp measurements useful? We would likely also need to add a volume to surface area ratio calculation. It really is frustrating isn’t it?

[wobbly]

Frits , yes absolutely correct if I was supervising another PhD thesis , but using Kelvin the difference is 5.9*C and this is totally insignificant such that I doubt any change would be visible
in any of the sim outputs.
And yes , trying to ascertain the average inner wall temp is a math logistical nighmare , easy to datalog as I did with PK screws holding K thermocouples in place, but quickly shown the
too hard basket when trying to use the data.
For the very specific Snow application , you only need one dyno session to get the best power egt , then using the power curve that gives you , input the start and end wall temp numbers in the sim
to generate an identical shape and peak rpm correlation.
These numbers will then work ad infinitum to enable you to rely on the results given by new pipe geometries.

[senso]

Although your engine has the long cylinder studs, it seems someone has managed to have aux ex-ports in it. Might be worth looking into.

The NS1 cylinder has a bridge port exhaust and not the single oval as the 50cc, or the older MBX air cooled cylinders.

[andreas]

Yes, I had the impression it was just one port.

[lodgernz]

The NS1 cylinder has a bridge port exhaust and not the single oval as the 50cc, or the older MBX air cooled cylinders.

The NS-1 75cc engine was just a slightly underbored NSR80 engine.
I'm guessing that the reduced capacity was to meet a European learner bike limit.
The original NS-1 was Japan-only and a 50. Otherwise the same bike.

[Ns1Montesa]

Josh, with additional boyesens, try to close crankcase intake port ( fully or partially, red line) , this is very easy to do with the base gasket. It was like, close the door when another opened.
Port map looks like really capable for 20hp.

I will test that!



Hi Josh. I believe that grinding away (i.e. raising) the separator between the A & B ports a few mm allows some of the charge coming through the Boyesen ports better access to the A port. Without this, only the B ports benefit from the Boyesen flow.
Also, there are a lot of sharp edges on the lower cylinder outer that can impede flow. If you look into the reed cavity you'll see that the incoming charge has a lot of disturbance from these sharp edges and corners. Easy to smooth these off.

Although you can't get any really nice after-market cylinders any more for these engines, you can get a 44mm stroke Italkit crank, and you can of course bore them up to 54mm. You might be able to find a Malossi 53mm cylinder, which are cast-iron but with quite nice transfers. The exhaust timing on these is mild, but as it is cast-iron, easy to improve.

And if you really want to spend some money, get a VHM head with insert. They work well.

After all that, it is really matching the pipe to the cylinder that will determine the power.


Hi lodgernz,

the ns1 engine is already a very short stroked engine (bore x stroke 48 x 41.4). Thats why I dont wont to go any further with the bore.
The italkit crankshaft looks nice. Maybe I buy one.
VHM head looks nice as well. But I want it low budget. Modified my head for 50 percent squishband and 1mm gap. Maybe there is some power to gain, if i test some different shapes and CR`s. Added a pic of a head I cut in halfs for research. I think there is plenty of meat for different shapes.

Next step is to test Katinas idea. If I am not abel to get the boyesens working, I will close them with expoxy. Also I am working on some test pipes. But I am not the most experienced sheet metal worker, so it takes a while :bash:

cheers

josh

[Frits Overmars]

Modified my head for 50 percent squishband and 1mm gap. Maybe there is some power to gain, if i test some different shapes and CR`s. Added a pic of a head I cut in halfs for research. I think there is plenty of meat for different shapes.Josh, why the 1 mm gap? 0,4 mm should be safe, and it will give a far better squish action and combustion velocity.
There is plenty material in that head, but you can't afford to remove much of it. It needs all of its stiffness, because the studs are so far apart and there are only four of them. Keeping the head gasket in place could become a problem.

[Ns1Montesa]

Hi Frits,

I already tested 0,45mm by accident. Used base gasket made of 1mm sealing paper. After I tigthened it up the gap was at 0,8mm. After testride the gap was at 0,45mm, because the paper could not stand the pressure. Luckily I noticed bad noises comming from the engine early enough. The result is shown in the picture:brick:
I used thick sealing paper because I wanted to geht rid of aluminium plate + liquid sealing.
Now I know that the crank is stiff enough for 0,45mm gap. But for some reason my engine is prone for detos.:wacko:

Hopefully I find a small lathe in near future, so I am able to do some heads.


cheers

josh

[Frits Overmars]

Hi Frits, I already tested 0,45mm by accident. Used base gasket made of 1mm sealing paper. After I tigthened it up the gap was at 0,8mm. After testride the gap was at 0,45mm, because the paper could not stand the pressure. I used thick sealing paper because I wanted to geht rid of aluminium plate + liquid sealing. Now I know that the crank is stiff enough for 0,45mm gap. But for some reason my engine is prone for detos.Josh, 0,45 mm squish should make the engine more deto-resistant, but because of the squeezed base gasket the compression ratio will have risen quite a bit. Moreover, the squish geometry on many Honda engines is less than perfect, with mixture entrapment in the outer part of the squish area.

You were lucky to experience the base gasket squeezing with that Honda cylinder with its long studs. Many cylinders with short studs and ears would show their displeasure by having an ear break off. Kawasaki and KTM are notorious in this respect. If you need to raise the cylinder more than 0,2 mm, better use a metal gasket, sandwiched between the thinnest paper gaskets you can find. Or do it the quick and dirty way and apply liquid sealing. And do not overtighten the stud nuts.
346694

[Muciek]

Ditch paper gaskets and go with (gambit af oil 0,3; 0,5; 0,8;
1,0;1,5; 2,0; 2,5;
3,0; 4,0; 5,0; 6,0 ) or reinz rs gasket material (this starts at 1mm thickness)... It should be available in Germany.
346695346696

[andreas]

0.7 squish on this 64.8 stroke. 3 1-mm alu spacers and four gaskets because of ebay piston suppliers.

[wobbly]

What Frits said.
The closer squish will increase the com as well as increase the squish turbulence - that has the same effect as advancing the ignition by lifting the flame speed.
You can pull out some advance if running a digital ignition , or simply retard the stator some.
And yes , check that the squish band is not the many times stupid reverse taper , whereby the end gases are trapped at the outer edge , near the bore.
With the exact result you have shown , piston edge deto.

[Vannik]

I know a lot do not follow the 50cc pages on Pitlane but there are some very interesting threads, in English!

http://www.pit-lane.biz/t8449-dtt-gp50#442165

http://www.pit-lane.biz/t6610-50cc-peugeot-103-and-ktm50-tuning

[andreas]

Two points re pipe design and CVT.
Firstly is that " fat " pipes are only effective on porting layouts that have good transfer duct geometry , and good radial port geometry.
If the ducts are not " teacup " and the most important A port front wall is not pointing back to just in front of the boost port , then the efficient diffuser section easily overcomes
the transfer stream coherency , giving huge short circuiting directly out the Exhaust duct.
This makes the jetting appear rich , but in actuality the mixture within the cylinder may be burning at near optimum temperature.Lean this scenario down at your peril.
A good example being a TZ350 that will simply refuse to make more power with anything past 110mm belly diameter

Secondly , the clutching setup.
As Frits alluded to , the clutching setup seems at odds with keeping the engine at peak power continuously.
My experience with CVT is nill , but for many years we raced KT100 Yamaha with centrifical clutches and specially designed pipes to make alot of power over a narrow range.
In this scenario the fastest setup was to have the clutch springs and weights " just lockup ", and allow the engine to sit at peak torque rpm under full load.
Then from this start point , the gearing was selected to give peak speed just as it dropped over peak Hp.
The clutch lockup rpm was critical to within 100rpm and was typically 10400 rpm , and the pipe was over the top at just past 14,000.


Because of A-port entry angle, this cylinder (as is) can't benefit from a modern style wide diffuser?

[wobbly]

Plenty of room to change the angle with a hook as the duct goes around the corner.The Exhaust duct is WAY too short as well , weld on a cooled extension to stop hot gases from being shoved
back past the rising piston by the rear cone.

[andreas]

Thanks Wobbly

[jfn2]

Has anyone completed or even started a EngMod2T file on the Kawasaki KX 65cc engine? I just picked up a Kx65 and want to build a file on it. I do not have the engine apart yet, and probably won't be able until the grandson is done running it, to check any measurements. I hear it is blowdown defeicant. Any knowledge from anyone? I am pretty sure it is stock. I checked with Vannik and he doesn't have a file so I'm asking in the forums. Thanks for any help. Jeff

[andreas]

Playing with my new slip roller.

[Condyn]

Make a cone guide so you can quickly roll accurate cones without further manipulation.

[diesel pig]

Make a cone guide so you can quickly roll accurate cones without further manipulation.

That would be very interesting to see that working. Please let us know how you get on with it. Cheers

[andreas]

Make a cone guide so you can quickly roll accurate cones without further manipulation.

Yes, I have to make one.

[flyonly]

Make a cone guide so you can quickly roll accurate cones without further manipulation.

How does the cone guide work please


Sent from my iPhone using Tapatalk

[andreas]

It's a rest for the inner curv of the metal to make it rotate around y axis while being rolled- maybe easier to see in a video.

[Ns1Montesa]

Josh, with additional boyesens, try to close crankcase intake port ( fully or partially, red line) , this is very easy to do with the base gasket. It was like, close the door when another opened.
Port map looks like really capable for 20hp.

I made a dyno run with duct direct to crankcase completely closed. Only Boyesens and ports in the cylinder bore open. I am suprised, engine makes exactly the same power. I will no longer spend time trying to optimise the intake. I think in my case it is not worth the time and effort. Thanks anyways Katinas!


Josh, 0,45 mm squish should make the engine more deto-resistant, but because of the squeezed base gasket the compression ratio will have risen quite a bit. Moreover, the squish geometry on many Honda engines is less than perfect, with mixture entrapment in the outer part of the squish area.

You were lucky to experience the base gasket squeezing with that Honda cylinder with its long studs. Many cylinders with short studs and ears would show their displeasure by having an ear break off. Kawasaki and KTM are notorious in this respect. If you need to raise the cylinder more than 0,2 mm, better use a metal gasket, sandwiched between the thinnest paper gaskets you can find. Or do it the quick and dirty way and apply liquid sealing. And do not overtighten the stud nuts.
346694


What Frits said.
The closer squish will increase the com as well as increase the squish turbulence - that has the same effect as advancing the ignition by lifting the flame speed.
You can pull out some advance if running a digital ignition , or simply retard the stator some.
And yes , check that the squish band is not the many times stupid reverse taper , whereby the end gases are trapped at the outer edge , near the bore.
With the exact result you have shown , piston edge deto.



Frits and wobbly, you are right. Shape of the head is not following piston dome perfectly. I pushed the piston against the head and twisted it. You can see the "ring" on head and piston.
If my calculation is correct, comp was around 14:1. In combination with bad shape this was a bit to much, as I am using 98 octane gas from petrol station.
I have to fix the shape issue and lower the gap.

Thanks.

cheers

josh

[Frits Overmars]

Nothing to do with two-strokes, but I think you may want to see this anyway: footage from yesterday's Austrian MotoGP, the most spectacular GP, fortunately with a happy ending, that I have ever seen.

Moto2 crash
https://www.youtube.com/watch?v=muEW5EwHl08

MotoGP crash
https://www.youtube.com/watch?v=UGPrHj1nPt0

https://www.youtube.com/watch?v=q2oVM2SAIfM

[yatasaki]

When you find yourself for few weeks in city of Pesaro first what you think of are two strokes.
TMracing closed for ferragosto...
Morbidelli museum not existing any more..
Benelli museum..now we are getting started, one floor is reserved for motoBi buckets and found piovaticci 125 (air cooled head and watercooled barrel) and mba250 piston ported air cooled.

Lazzarini bmw store...offers 12 gp bikes from kreidler, iprem (looks like kreidler to me) and piovaticci 50 to125 garelli, morbidelli and mba which could tell a lot of stories at least technical..if Italians would or could talk english. A pleasant guy gave me some notes about Lazzarini bikes..on dutch
Some pictures tomorrow

[Frits Overmars]

When you find yourself for few weeks in city of Pesaro first what you think of are two strokes. TMracing closed for ferragosto... Morbidelli museum not existing any more. Benelli museum..now we are getting started, one floor is reserved for motoBi buckets and found piovaticci 125 (air cooled head and watercooled barrel) and mba250 piston ported air cooled. Lazzarini bmw store...offers 12 gp bikes from kreidler, iprem (looks like kreidler to me) and piovaticci 50 to125 garelli, morbidelli and mba which could tell a lot of stories at least technical..if Italians would or could talk english. A pleasant guy gave me some notes about Lazzarini bikes..on dutch
Some pictures tomorrowTM racing closed for ferragosto? Make that 'Italy closed for ferragosto'; Italians are pretty resolute about summer holidays. I remember trying to get some work done in a racing department in August; I couldn't even buy an M6 bolt in Italy in August. Until I mentioned 'Reparto Corse', then suddenly anything became possible. Nice people. And they are quite willing to talk English, if only they could.
If you run in to Eugenio Lazzarini, please give him my regards. He is one of the nicest guys you can hope to meet.

[yatasaki]

Didn't mean to be annoying to no Italian in ferragosto. If Mr. Lazzarini would be present at the time I would ask him for half an hour of his time.
Very nice people and place indeed.
TM opens on monday but we're gone tomorrow. Corona is uprising again..Have missed twelve bucket races this month because of Pesaro but let's say it was worth it.

[Frits Overmars]

Didn't mean to be annoying to no Italian in ferragosto. If Mr. Lazzarini would be present at the time I would ask him for half an hour of his time. Very nice people and place indeed. TM opens on monday but we're gone tomorrow. Corona is uprising again..Have missed twelve bucket races this month because of Pesaro but let's say it was worth it.The pictures you took at the Museo Lazzarini brought back memories. The cylinder sleeve is from Lazzarini's Maico-engined 125cc Piovaticci. Jan Thiel, who just had joined Piovaticci in 1975, had a brief look at it, after which it was one of the fastest Maico-engined bikes of its time. Funny that its 27 hp was exactly half of what Jan later extracted from the Aprilia RSA125.

Lazzarini naturally wanted to show the internals of the Garelli 125cc twin on which he was very successful. He would have been a multiple 125cc world champion on that bike, if it hadn't been for a bloke named Angel Nieto, who happened to be in the same works team and took the title six years in a row.

Lazzarini took his racing job very seriously, keeping fit during the off-seasons by doing a lot of sport, eating healthy, no smoking and no drinking. Nieto on the other hand spent his off-seasons at Ibiza, smoking and drinking all he could, while his sporting activities mainly consisted of multiple push-ups. Multiple meaning: he wasn't alone while doing 'm. Then, when the racing season started again, Nieto went on winning and Lazzarini kept collecting second places.

But I was talking about the Garelli innards in the Museo Lazzarini. The carburettors are genuine but the cylinders are not; the real deal had four additional head studs. But I can understand that Lazzarini displays a couple of lookalikes because the originals are really rare (I've got one at home :msn-wink:).

Below Jan and Eugenio at the Piovaticci dyno in 1975, Nieto and Lazzarini on the unbeatable Garelli 125cc twins, the internals of the Garelli twin, and the parts in the Museo Lazzarini.
346927 346926 346925 346924

[yatasaki]

There, few more to come

[jbiplane]

One interesting topic to discuss. Classical tuning pipe could be to bulky for many applications.
Rc model helicopters use different compact expansion chambers which are lightweight and compact.
http://www.os-engines.co.jp/90824/images/pb05.jpg
I trying to make design of tuning pipe screwed to spiral. Any other ideas or experience?

[yatasaki]

Frits whats the story with van Veen and iprem kreidler?

[Frits Overmars]

Frits whats the story with van Veen and iprem kreidler?I couldn't say. For all I know it was a Van Veen production racer, tuned and ridden by Lazzarini and sponsored by Iprem. Eugenio should be able to tell you all about it if you see a chance to meet him before you leave Pesaro.

[SwePatrick]

Long time no see ;)
I´ve been busy building.
A friend of mine sent me a TZR250 engine from Greece.
I bought an old TZ spondon frame.

It´s built for 'moped dragracing' biggest class.
This is second startup, still a lot to adjust, is a very mild ignitioncurve in video.
But it sounds promising.

It is a Hybrid, newer 3xv jugs(ported) on an old 1kt engine.
Further on after testing it will be downsized in bore to meet up with classrestrictions(212cc)
it is 250cc now, searching for pistons, 50mm bore and 16mm wristpin, one ring, gap at 6 o´clock.
Feel free to point me in right directions if there are any ;)


https://www.youtube.com/watch?v=_x0XLijeSUk

[Muciek]

Will You use ignitech to control the airjets on the carb or there will we fixed ones used?

[husaberg]

Long time no see ;)
I´ve been busy building.
A friend of mine sent me a TZR250 engine from Greece.
I bought an old TZ spondon frame.

It´s built for 'moped dragracing' biggest class.
This is second startup, still a lot to adjust, is a very mild ignitioncurve in video.
But it sounds promising.

It is a Hybrid, newer 3xv jugs(ported) on an old 1kt engine.
Further on after testing it will be downsized in bore to meet up with classrestrictions(212cc)
it is 250cc now, searching for pistons, 50mm bore and 16mm wristpin, one ring, gap at 6 o´clock.
Feel free to point me in right directions if there are any ;)


https://www.youtube.com/watch?v=_x0XLijeSUk

Nore sure re the peg but YZ100 is all of those but might have windows.
F5dave might have one left to measure.
fctory was 1 ring i think and wiesco was 2 ring

[SwePatrick]

Will You use ignitech to control the airjets on the carb or there will we fixed ones used?

There are no elecric valves at all on these carburetors, they are from rgv250 and bored out to 35.5mm(as i will run less volume in engine later on)
And i figure there aren´t need for any as i only run 201m(1/8th) and running either methanol or e85.

But i could use it if wanting to make things more refined and difficult ;)

[F5 Dave]

I might have bits of one. Yeah factory was 1 ring. Did it have big 1/2 moon in the back? Jeez seems like a lifetime ago.

Edit. Yeah that's right. Peg was at 7 o'clock though.
Have a look on Evilbay.

[andreas]

Swepatrik, Yz 100 pistons meet your specs, but for the rings. Ok, this is brought to attention allready.

[husaberg]

https://www.youtube.com/watch?v=jdn7VHt6sgA

[SwePatrick]

I have ran in to some misfires thou,, a question for you ignitech users:

Is it possible for misfire to develop if having wrong plugwires?
I have measured the original cable that came with my ignitech, it measures about 27Kohm
And plug wires i have right now measures way lower, only 26.5ohm

My ignitech is from the beginning bought for one cylinder.
But i use two sparks per revolution and double lobe triggerwheel.
Now when i bought a new double coil i didn´t have plugwires so i made new ones from MSD cables, never thought about the low resistance.
New coil has the same values as the old.

Rgds.

[wobbly]

Neither measurements make sense .
Normal solid copper wire leads will measure almost nil resistance over say 300mm.
MSD say that their Super core wire should be 50 ohms / per ft , and the Street Fire about 500 ohms / ft , this type of EMI suppressor wire is used for MSDs CDI high power digital systems.
Ignitechs must be run with a 5K plug resistance AND a 5K resistor cap , again to supress EMI from giving false triggering and misfires.
I have never used high resistance supressor wire , just high quality solid copper with the correct cap and plug - never had any issues with missfiring.

[SwePatrick]

My msd cables are about half a feet, so 26.5ohm would be about correct.
And for the other value it´s magnecor cable, AND my multimeter is cheap ;)
And,, add that i´m no genious at understanding my multimeter *lol*
(My magnecorcable is probably set up with a resistorcap already)

Got ansver from Martijn that low resistance cables can disturb the ecu.

So i´ll test some other cable this evening.

[husaberg]

My msd cables are about half a feet, so 26.5ohm would be about correct.
And for the other value it´s magnecor cable, AND my multimeter is cheap ;)
And,, add that i´m no genious at understanding my multimeter *lol*
(My magnecorcable is probably set up with a resistorcap already)

Got ansver from Martijn that low resistance cables can disturb the ecu.

So i´ll test some other cable this evening.

'Sweden still metric isn't it
despite what trump knew happened.


https://www.youtube.com/watch?v=ak3-YHxoKyc

[andreas]

It's a twin.

[wobbly]

The other thing to consider is that with a double ended secondary coil you only get 1/2 the spark gap energy per side.
Try dropping the gap down to 0.4mm.
Also it requires much less energy to fire the modern Platinum/Iridium plugs like R7376.

[SwePatrick]

'Sweden still metric isn't it
despite what trump knew happened.


Haha =)
World leaders sometimes...

[SwePatrick]

The other thing to consider is that with a double ended secondary coil you only get 1/2 the spark gap energy per side.
Try dropping the gap down to 0.4mm.
Also it requires much less energy to fire the modern Platinum/Iridium plugs like R7376.

I found the problems, First i changed the plugwires and added 5k hats.
Then i had the 'baseadvance' way wrong, somehow the ignitech lost it´s memory, didn´t think of it.
But i saw the curve was like a 4 stroke curve to begin with, i changed that before first start, but missed that base advance had 21degrees to it.
My triggersetup should always have zero degrees.

Now it starts to sing.
But nowhere near to be fully tuned yet, as i have searched misfires, the fun stuff begins now ;)


https://www.youtube.com/watch?v=-SFP0JemAXU

This was yesterday, like a huge rock dropped from my shoulders, finally no pops and bangs. :D

Edit: i run iriduim plugs, but these: ngk br9ecmix (oem ktm sx125)

[F5 Dave]

Well it sounds nice

[Pursang]

Reports of the Death of 2 Strokes have been Greatly Exaggerated!:yes:

22-year-old-honda-cr500-two-stroke-takes-on-450-four-strokes-at-the-british-amca-championship

https://motocrossactionmag.com/22-year-old-honda-cr500-two-stroke-takes-on-450-four-strokes-at-the-british-amca-championship/

Not to mention... Neville Bradshaw is a 37 Years Old Privateer racing against 22yo Kids on Factory kitted 450's.

Worth watching to the end for MX fans. 3 Heats: 5th, 3rd and ???

Cheers, Daryl.

[andreas]

He's been doing it for a while, this time on a -89. And as we know the cr 500 gets better the older it is.
https://www.youtube.com/watch?v=pvFuZFeTbIQ

[SwePatrick]

Was meant to tune the bike today, i did a couple of dynoruns, but clutch slipped badly, REAL badly, expected clutch to be a weak point but this was really a LOT.

However i filmed a little warmup and then took two screenshots of the bad slip.
when dyno is flashing zero rpm, it is the rpm limiter that is hit, (13000rpm), no signal to coil = no reported rpm in dyno.

First the clip:

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

First pull(the best of three):
https://forumbilder.com/images/2020/08/29/slip1.jpg
Just out of the box, really really bad slip, 35hp,, nothing to brag about *lol*

Second pull(the best of three):
https://forumbilder.com/images/2020/08/29/slip2.jpg
Before this pull i shimmed the springs in the clutch and also lowered the oil level in gearbox as i noticed it was way to much even though i put one litre in as it says on the clutch cover.
In this series of pulls the clutch started to slip and then it kind of jerked and let go again, really bad, but i got 44.8hp to the wheel with still insanly slipping clutch.
Yellow lines is engine rpm, and it starts to slip at about 7500rpm

So a question, Are there any good clutch upgrades for 1kt engines?

Rgds
Patrick

[F5 Dave]

Never seen one but on my RZ with machining of hub and washer I got another plate pair in. More area is always the best. You can skim the steels but too thin and they will warp. I'd be favouring the gearbox lubrication over any perceived reduction of slip.

[SwePatrick]

I´m looking at 3ma clutch, it got 5 springs, 1kt has 4 springs.
The clutch discs are the same between them.

Need to know if the splines is clutchcenter are the same.

[wobbly]

What dyno software is that , seems wierd to have rpm on the Y axis.
Doesnt the software have the ability to input the actual speed drop ratio from the dyno shaft ( once you have done one pull ) thus you dont need to smooth the rpm chanel and then this can
be shown on the X axis as is normal ?

[SwePatrick]

It is sportdyno 4.1
I just made this screen to show how badly the clutch slips.
Normally i just show hp and torque
but theese two screens show hp and engine rpm.
I forgot to show dynoroller speed, but it is a straight line in both runs, slightly leaning upwards to the right as the speed increases, not as the engine rpm, who just hits the roof and sits there.

I thought it was crystal clear ;)

I can also add more filtering, but that just smoothes everything out, i wan´t to see jerks peaks and valleys.

[TZ350]

It is sportdyno 4.1 I thought it was crystal clear ;)

Me too, unusual layout but easily readable. RPM and HP relates Ok. The slipping clutch gives the HP curve that CVT look.

[speedpro]

If you machine the steel clutch plates only reduce the thickness of the plain part that the friction plates rub on. Leave the tooth part that engages the clutch centre part full thickness so the standard thickness is engaging. Easier on the alloy bit that way.