ESE's works engine tuner

[wobbly]

The issue with any offset to a chamber in a 2T is that no matter what, you end up with the MSV off the scale on the wide squish side, and no MSV on the other.
This was a huge issue in the old TZ250G model, that would detonate as soon as the jetting was even close.

[Haufen]

One of the ideas I've pondered experimenting with, is to offset the chamber to the exhaust side. That approach is proven to work very well in 4-strokes allowing a lot more compression and reduced ignition lead, but can't say what to anticipate in 2-stroke. Should at least improve the piston cooling and charge vaporization somewhat. Easy to try though.

I can confirm your statement for an industrial engine with no proper utilization of the squish effect. As soon as there is some charge motion by SV, it was superior to have the chamber in the middle as already written by wobbly (and to have a MSV as high as possible).

[dutchpower]

Dutchpower - the Transfer STA being so huge ( as they are very wide obviously ) in comparison to the Blowdown STA, means that if the Delivery Ratio is sufficient to
actually flow enough air to make 38.9Hp via the transfers,then you will get the classic scenario of a huge residual combustion pressure at TPO.
The nowhere near sufficient Blowdown will create a large reverse flow down the A transfer ducts, as they open first, creating havoc with the scavenging regime.
So I believe that when you have a fatally flawed scavenging setup like that, lifting the Ex duct floor for sure wont be able to increase power.
The perfect example was shown by Jan when developing the Aprilia, that lifting the duct floor only made power once the Blowdown was optimally matched to the Transfer STA.

Thanks Wobble


I made transfer time area as big as possible ( Jan Always say every square mm counts )

[wobbly]

Again in this case the Blowdown is still a mismatch with the Transfer STA.
This would be OK if the duct geometry is compromised, and then its normal to increase the Transfer area to help with the
bad effect the ducts have on flow capability.
What scavenging regime are you inputting with these huge transfers, and why is the Blowdown still limited ?

[dutchpower]

Again in this case the Blowdown is still a mismatch with the Transfer STA.

Can you explain this more




Thanks Wobbly

[Muhr]

If anyone thinks it's interesting with water CFD:blink:

blue is weak circulation

The exhaust duct above the exaust flanch is the hot spot Iam working on ringt now.

[wobbly]

In the new file we have a Blowdown Power Capability of 30.4 Hp and a Transfer Power Capability of 34 Hp.
The original file showed the Inlet as capable of 33.71Hp so that is close to the new transfers.
What you now need to do is increase the Aux Exhaust port area or timing to get up around 34 Hp as well for the Blowdown.
If you dont,then the low Blowdown will have all the bad consequences I explained before.
The actual overall Ex port effective area is redundant,and is usually low, meaning in practical terms the duct volume will be lower - a good thing..
Another thing I noticed is that you have conventional port stagger ie A port opening first - but the boost port is up at the same timing as the B port.
To get the mid power advantage of this scavenging regime the boost needs to be lower as well.

[ken seeber]

Makes me wonder why Aprilia went with the intake side offset cylinder head for ditech, as it's already proven not to be that great. To get the plug to the hot side?

One of the ideas I've pondered experimenting with, is to offset the chamber to the exhaust side. That approach is proven to work very well in 4-strokes allowing a lot more compression and reduced ignition lead, but can't say what to anticipate in 2-stroke. Should at least improve the piston cooling and charge vaporization somewhat. Easy to try though.

Jannen,
To locally contain the vertically downward injection stream, it was very clear (at Orbital) from the start that having some sort of bowl in the piston “reflected” the spray. This was key to low load type settings to achieve stratification, hence reduced HCs and increased BSFC.
At higher loads, this “reflection“ wasn’t required, as we were even injecting before BDC, particularly at higher rpm.
The sequence of development was to start off with an axisymmetric arrangement (referred to as Type 25), as per the central piston. Then, with time, the Type 23 (on the left) was developed, offering much improved characteristics for the 3 cyl, 85 hp, 1.2 litre automotive engine application (circa 1990). Unfortunately I don’t have any pics of the head shape, but it was flat with a well radiussed rectangular bowl above the bowl in the piston, this being above the inlet or transfer side.
As Wob has pointed out, the MSV difference from one side to the other is all over the place and, even knowing very little about this subject, can see it not conducive for a max power shape. However, as it was an auto engine where we were focussed on emissions and fuel consumption.
In setting the engine maps, particularly at high loads, we used a term MBT. This, within Orbital, meant minimum advance for best torque, slightly different to the alternate meaning of maximum brake torque. One tool was apply a realtime statistical analysis to the combustion pressure trace (we used Kistler 601 pressure transducers. Then, knowing a predetermined allowance for the onset of detonation, this determined the ignition timing at this point.
I wasn’t close to the Aprilia Ditech project, this was mostly conducted from Italy, but am pretty sure the same general combustion chamber shape & piston bowl were used, albeit scaled down. Have no idea of swapping the head around might achieve. One thing to be aware of is that it’d definitely be undesirable for the protruding piston bowl to run into the flat head face.
Just for a giggle, I have included on the RHS an early cross flow scavenged piston (probably ex Mercury or OMC). This should offer you the worst of everything, although I do believe the idling and low speed operation wasn’t too bad.
Disclaimer: As all this was around 30 years ago, putting me into dementia territory, there could be a touch of bullshit in the above.


335498

[F5 Dave]

Dementia aside I've been looking forward to hearing about your previous vocation even if it isn' directly racebike related

[Jannem]

The issue with any offset to a chamber in a 2T is that no matter what, you end up with the MSV off the scale on the wide squish side, and no MSV on the other.
This was a huge issue in the old TZ250G model, that would detonate as soon as the jetting was even close.

Did it loose power going with less ignition lead?

[Muhr]

If anyone thinks it's interesting with water CFD:blink:

blue is weak circulation

The exhaust duct above the exaust flanch is the hot spot Iam working on ringt now.

Port flow



vimeo.com/257472853 (http://vimeo.com/257472853)

[shnaggs]

Port flow



vimeo.com/257472853 (http://vimeo.com/257472853)


Muhr, What are you using for the coolant CFD? Still Fusion360?

[Muhr]

Muhr, What are you using for the coolant CFD? Still Fusion360?

In a sense, I'm using a plugin called Simscale. Fusion does not have CFD

[SwePatrick]

Muhr, What are you using for the coolant CFD? Still Fusion360?

Add a moving piston to the simulation =)
Edit: and decreasing pressure in crankhouse as the pistons moves.

[SwePatrick]

I have stumbled upon a problem.
To shape the B-transfers as i want i need more material above the transfers next to the 'water'.
At the outside of cylinder i can just add with welder, no problems.
But inside the waterjacket above the transfers is a problem.

I had this idea first with just wash with some acids and pour down a epoxi to build some material to grind in above the transfers.
But, then i got the next idea, how about do the same cleaningwork but then melt aluminium and pour down raise 'bottom' of cooling jacket.

This method has been used to save old ironheads for fourstroke engines when needing more meat to grind in.

Will it 'stick' to the surface good enough to secure a seal between the materials?

Rgds

[shnaggs]

In a sense, I'm using a plugin called Simscale. Fusion does not have CFD

Thanks, I didnt think Fusion had CFD, although it does have some sim stuff, so thats why I was asking.

[jonny quest]

Ken Seeber, the DiTech SR 50 has a domed piston.

[Tim Ey]

I have stumbled upon a problem.
Will it 'stick' to the surface good enough to secure a seal between the materials?

Rgds

Nope. It will have air to the barrel because of the thermal shrinking.
But if you pour in Aluminium, remove it afterwards and screw it in place with 2K glue in between it is dead serious.

[wobbly]

Simple solution to adding alloy above the transfers,within the waterjacket,is to acid clean it then use alloy stick weld repair rods.
The trick is to weld upward , so the molten flux runs down hill away from the weld pool.

The TZ250G had to run retarded timing to stop the det, and this did loose power but allowed leaner jetting so it would at least rev out as it should.
Then when you got it to rev, the pistons would fall into the idiot designed inlet port and would destroy themselves in about 100Km - the whole team that designed that piece of shit
cylinder should have been shot.

[SwePatrick]

I tried almost your way wobbly, just a couple of minutes ago.
I didn´t reach as you describe so i just started to weld,(material was about 1mm thick) and i pushed in a lot of weldingrod and heated and heated so it 'sinked' down into the waterjacket, had the cylinder upside down.

In middle of progress:
335502

[Frits Overmars]

The TZ250G... when you got it to rev, the pistons would fall into the idiot designed inlet port and would destroy themselves in about 100Km -
the whole team that designed that piece of shit cylinder should have been shot.That's one way of looking at it Wob. I'd say the TZ250G had by far the best gometry of all the 2-in-1 cylinder blocks.
You'd only have to shoot the Jap that fitted it the wrong way around. With the carbs up front all piston problems were gone.
335505

[peewee]

I tried almost your way wobbly, just a couple of minutes ago.
I didn´t reach as you describe so i just started to weld,(material was about 1mm thick) and i pushed in a lot of weldingrod and heated and heated so it 'sinked' down into the waterjacket, had the cylinder upside down.

In middle of progress:
335502

have you a tig welder ? ive found it to be a priceless tool and you can make many things

[wobbly]

Yes I agree Frits the duct geometry was well ahead of any other parallel twin,and that is why we started the LSR 350 engine with one.
Once you turn it around ( as we did for years in Superkart racing } as well as the LSR then the intake issue is null,as well as making really nice pipes easy to fabricate.
Luckily the earlier F model heads bolt straight on, and or hoovering out the G cover and adding inserts got rid of the dumb arse Dr Joe money making enterprise of offset combustion.
The last thing to try on the LSR 350 is to use 400 cases, shunting the case volume thru the roof, as well as NO chance of flywheel parasitic radial drag.

[husaberg]

Yes I agree Frits the duct geometry was well ahead of any other parallel twin,and that is why we started the LSR 350 engine with one.
Once you turn it around ( as we did for years in Superkart racing } as well as the LSR then the intake issue is null,as well as making really nice pipes easy to fabricate.
Luckily the earlier F model heads bolt straight on, and or hoovering out the G cover and adding inserts got rid of the dumb arse Dr Joe money making enterprise of offset combustion.
The last thing to try on the LSR 350 is to use 400 cases, shunting the case volume thru the roof, as well as NO chance of flywheel parasitic radial drag.

How move bigger volume are the cases?
I actually thought that once you go over 1-2mm clearance between the crnk wheels and the cases you will get boundary friction drag.
I ask this as i assume the crankwheels on the RD400 are quite a lot bigger than the 250/350 DS7/TZ/rd cases but i always thought most of the volume was from the taller deck cases.

[Haufen]

Port flow



vimeo.com/257472853 (http://vimeo.com/257472853)


Looks like it would be a good idea to make the duct straight and angle it more downwards. The RSA is at 25° iirc (for a square engine, that is. will be less for a big bore and vice versa).

[ken seeber]

Ken Seeber, the DiTech SR 50 has a domed piston.


Johnny, you're right. I googled for a pic and came up with this one of the head. Certainly spherical, but does feature the characteristic offset bowl and varying squish areas.

335507

[Muhr]

Looks like it would be a good idea to make the duct straight and angle it more downwards. The RSA is at 25° iirc (for a square engine, that is. will be less for a big bore and vice versa).

I think so too! I would like to use a shorter conrod i have as I get 13g less balanced weight. Perhaps it was a bad decision.
Tried to adjust some angles and get a little bit better, but I don't know.

https://vimeo.com/257676319

https://vimeo.com/257789800

[SwePatrick]

have you a tig welder ? ive found it to be a priceless tool and you can make many things

Yes, since i bought my first tig welder the old MIG/MAG is left dusty in a corner =)

[Frits Overmars]

Yes I agree Frits the duct geometry was well ahead of any other parallel twin,and that is why we started the LSR 350 engine with one....
The last thing to try on the LSR 350 is to use 400 cases, shunting the case volume thru the roof, as well as NO chance of flywheel parasitic radial drag.With the bigger case volume, your porting layout and the really fat pipes on the LSR bike, it should fly, Wob!


How move bigger volume are the cases? I actually thought that once you go over 1-2mm clearance between the crnk wheels and the cases you will get boundary friction drag. I ask this as i assume the crankwheels on the RD400 are quite a lot bigger than the 250/350 DS7/TZ/rd cases but i always thought most of the volume was from the taller deck cases.Boundary drag between crank wheels and cases rises steeply when you go under 1 mm clearance, Husa. But that's not the case here; the crankwheel diameter of the RD400 may be quite a lot bigger, but when you put a TZ350 crank in the RD400-cases, everything is fine.

[peewee]

Yes, since i bought my first tig welder the old MIG/MAG is left dusty in a corner =)

you can also get micro torch for weld inside exh port. i got this one new helmet yesterday. optrel made in switzerland :2thumbsup

[Frits Overmars]

you can also get micro torch for weld inside exh port. i got this one new helmet yesterday. optrel made in switzerlandCareful now, Peewee. If you carry on like this, you cannot blame the equipment any longer :D.

[SwePatrick]

you can also get micro torch for weld inside exh port. i got this one new helmet yesterday. optrel made in switzerland :2thumbsup

I´ve got a Speedglas helmet with my own graphics on it, had it for 15years i guess.
Must be the most quality weldinghelmet ever, never lets me down =)

Yes, i´ve seen those microtorches, i just about reached with my wp9 with stubby setup into exhaustport also, i welded up the floor a bit. :)

[Muhr]

If try continue from where Jan stopped, why not to try exhaust bottom at transfers upper edge level, and then grinding in small steps.
Interesting how bottom exhaust duct shape should look like with this configuration, parallel with upper and oval cross-section or something different,
of course with ......G, H,.......

Haufen had a point! maybe this is the way to go even from start.

[wobbly]

Looking at the latest 125 TM kart cylinders I have been working on,the best power is had from using the Aprilia 25* down angle on the roof that ends in a hump
just past where the Aux port exits into the duct.
The floor is horizontal to the same point,than ramps down.
This is keeping the duct volume down, especially where the Aux ducts intersect with the main duct.
As far as lifting the floor above BDC is concerned, just remember that Jan found power I believe at 2mm,then the tests ended.
So this is as far as has been dyno proven in a really well developed cylinder like this.
Another point re the water - after my tests on the ceramic coated duct I believe that you should have water right up to the flange face,and I go one further
and mill slots thru the flange face to cool the back of the bolt on spigot.

[husaberg]

Boundary drag between crank wheels and cases rises steeply when you go under 1 mm clearance, Husa. But that's not the case here; the crankwheel diameter of the RD400 may be quite a lot bigger, but when you put a TZ350 crank in the RD400-cases, everything is fine.
Hanks Frits Well i sure had that backwards.
I remember you mentioning the TZ with RD400 previously, so how much extra power are you talking here?

[Muhr]

Looking at the latest 125 TM kart cylinders I have been working on,the best power is had from using the Aprilia 25* down angle on the roof that ends in a hump
just past where the Aux port exits into the duct.
The floor is horizontal to the same point,than ramps down.
This is keeping the duct volume down, especially where the Aux ducts intersect with the main duct.
As far as lifting the floor above BDC is concerned, just remember that Jan found power I believe at 2mm,then the tests ended.
So this is as far as has been dyno proven in a really well developed cylinder like this.
Another point re the water - after my tests on the ceramic coated duct I believe that you should have water right up to the flange face,and I go one further
and mill slots thru the flange face to cool the back of the bolt on spigot.

Thanks wobbly I'll look into it. Just raise the bottom made surprisingly little change on the flow image

[SwePatrick]

Looking at the latest 125 TM kart cylinders I have been working on,the best power is had from using the Aprilia 25* down angle on the roof that ends in a hump
just past where the Aux port exits into the duct.
The floor is horizontal to the same point,than ramps down.
This is keeping the duct volume down, especially where the Aux ducts intersect with the main duct.
As far as lifting the floor above BDC is concerned, just remember that Jan found power I believe at 2mm,then the tests ended.
So this is as far as has been dyno proven in a really well developed cylinder like this.
Another point re the water - after my tests on the ceramic coated duct I believe that you should have water right up to the flange face,and I go one further
and mill slots thru the flange face to cool the back of the bolt on spigot.

Yes, I have drawn a pic of how i´m designing my new cylinder, it is very similar to your drawing actually.
Then i drew that idea of water all into the flange, roostcylinders for scooters have this design.

Then also another thing, i altered the auxports on picture to be more similar to my porting.
I don´t want the wristpin to pass over the port to much as it is expensive to laserweld the wristpin shut in the ends like Aprilia did.

335523

[Frits Overmars]

I don´t want the wristpin to pass over the port to much as it is expensive to laserweld the wristpin shut in the ends like Aprilia did.The wristpin passing over the auxiliary exhaust windows need not be a problem Patrick. The problem arises when the wristpin passes over those aux windows and the transfer windows simultaneously, as indicated by the yellow circle in the first picture. That is why the aux ports in the Aprilia cylinders have sloping undersides in order to minimize the port area in the 'danger zone'.
Laserwelding the wristpin ends is not the most effective solution. You might want to try the type of synthetic plug that I developed.
They are closer to the cylinder bore and fairly easy to produce, although the necessary material, Torlon, is not cheap.

[SwePatrick]

Nice Info Frits, Thanks.

I had the problem in an earlier build, long time ago, thereby my caution.
It was like a handgrenade in the crankhouse, it flew reedpetals all over the garage, and it actually chopped off the needle in the carb =)

[Frits Overmars]

I remember you mentioning the TZ with RD400 previously, so how much extra power are you talking here?I don't remember Husa; it was about 40 years ago, when the TZs still came with 34 mm Mikunis. In combination with the bigger crankcase volume we fitted 38 mm carbs to the TZ250 and 40 mm to the TZ350. With hindsight that should have been about 44....

[JanBros]

someone asked me if it was possible to switch of the wobbly-duct for 2/3stage in my FOS excel. it wasn't so I changed it now.
also added volumes.

http://users.telenet.be/jannemie/FOS%20PIPE%20black.xlsm

[lodgernz]

Never seen this before. Usually it's the rear skirt that breaks, as it's the thrust face.
From my 50 after 10.2 hours thrashing at race pace. Not all at once of course. Over a year or so.
Any comments? Looks a bit like fatigue.

335533

[Muhr]

Thanks wobbly I'll look into it. Just raise the bottom made surprisingly little change on the flow image

I can not manage to get any circulation when I try to approach the flange, I've tested a lot of different variations but the only thing that gives results is area and that's something I haven't got. It's easy to forget how small it is when sitting in CAD:wacko:

[husaberg]

Never seen this before. Usually it's the rear skirt that breaks, as it's the thrust face.
From my 50 after 10.2 hours thrashing at race pace. Not all at once of course. Over a year or so.
Any comments? Looks a bit like fatigue.

335533
Why is the gudgeon bore so black? Actually looks sooty.

[tjbw]

Never seen this before. Usually it's the rear skirt that breaks, as it's the thrust face.
From my 50 after 10.2 hours thrashing at race pace. Not all at once of course. Over a year or so.
Any comments? Looks a bit like fatigue.

335533

Looks brittle! Is there a polished fatigue surface in the shadow?

[F5 Dave]

Measure bore wear Roger. Usually takes out inlet but vould gave been weak in that piston front.

[katinas]

.........
Laserwelding the wristpin ends is not the most effective solution. You might want to try the type of synthetic plug that I developed.
They are closer to the cylinder bore and fairly easy to produce, although the necessary material, Torlon, is not cheap.

Yellow Torlon plugs looks nice, simple and effective.
Long time ago, made wirstpin plug in more complicated way. Found 25 year old piston with this plugs.
Torlon is fantastic material. Once made thrust washers for small end bearing from Black Torlon and they work fine.

[lodgernz]

Why is the gudgeon bore so black? Actually looks sooty.
No, just sort of cast-piston-grey.


Looks brittle! Is there a polished fatigue surface in the shadow?
Well spotted! Looks like a very slight polish there. Maybe where the breakage started?
335538335539


Measure bore wear Roger. Usually takes out inlet but vould gave been weak in that piston front.
Bore is all good I think, 0.06mm clearance at the bottom. I'll check it all around in case there's an ovality somewhere.

[katinas]

Never seen this before. Usually it's the rear skirt that breaks, as it's the thrust face.
From my 50 after 10.2 hours thrashing at race pace. Not all at once of course. Over a year or so.
Any comments? Looks a bit like fatigue.

335533

Maybe, squash gap is too small and sometimes piston touching the head.

[Muhr]

Never seen this before. Usually it's the rear skirt that breaks, as it's the thrust face.
From my 50 after 10.2 hours thrashing at race pace. Not all at once of course. Over a year or so.
Any comments? Looks a bit like fatigue.

335533

I've seen it before on cast iron sleeve cylinders probably because of pistonclerence. I have thought it was because of curb jumping

[F5 Dave]

0.04 would be better for 40mm bore but it's certainly not doing somersaults in there.
There's not much back to that piston so replacement schedule may have to decrease

[lodgernz]

Maybe, squash gap is too small and sometimes piston touching the head.

No sign of contact, apart from where a few bits of the skirt have made their way up the transfers and out the exhaust. Squish gap was 0.75mm.


I've seen it before on cast iron sleeve cylinders probably because of pistonclerence. I have thought it was because of curb jumping
The cylinder is cast iron, but piston clearance seems OK. Kerb jumping is unavoidable in bucket racing. For me anyway.


0.04 would be better for 40mm bore but it's certainly not doing somersaults in there.
There's not much back to that piston so replacement schedule may have to decrease

Back face is in really good order, but yeah, agreed.

[Grumph]

Have you got access to dye penetrant crack test gear ? I've reached the stage of life/cynicism where I automatically test pistons esp if they're NOS.

Surprising what you find too...

[jonny quest]

Is that a $6 China piston from Ebay? There's your answer.

[lodgernz]

Have you got access to dye penetrant crack test gear ? I've reached the stage of life/cynicism where I automatically test pistons esp if they're NOS.
Surprising what you find too...

I'll check around.


Is that a $6 China piston from Ebay? There's your answer.

Ha ha, no, USD70 Kitaco piston made in Japan. Chinese one wouldn't have lasted 10 tough hours.

[Jannem]

Is there a reason why the atac valve should be in the header. Would it work in the side of the expansion chamber the same?
Or at the end of it?

[TZ350]

Is there a reason why the atac valve should be in the header.

Good question, to find out, try this search:-

atac valve site:www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner (http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner)

335557

[Jannem]

Thanks, tried it already.

I guess the question could also be formulated differently:
Does the main benefit from atac come from the volume change or or out of phase standing wave at a specific point in the pipe near ex flange)?
All previous discussion is about the location in the header.

The reason I’m asking is an idea about combining adjustable volume and stinger size at the end of the pipe, which would be simple to implement.

It would be adjustable for stinger separately for valve open and valve closed and would also increase pipe length for open. Only one simple moving part with no sealing issues.

[Frits Overmars]

... an idea about combining adjustable volume and stinger size at the end of the pipe, which would be simple to implement.Something along these lines Jannem?
335558

[Peter1962]

Something along these lines Jannem?
335558

Frits, to your knowledge, has anyone allready tried & tested this design ?

[wobbly]

My understanding of the ATAC sitting near the cylinder exit is that the stuffing pressure wave returning up the header at the wrong time ( due to the pipe length being mismatched to rpm)
is reduced in amplitude when it encounters the relatively large side volume by the opened valve.
Several manufacturers use this idea in concert with the power valve,in that when it is down,the Exhaust duct is connected to a volume within the sides of the cylinder via a hole in the
PV drum or blade.
When the PV rises,this hole is blocked of.
Killing the return wave pumps up the lower end power by reducing the pipes efficiency, exactly the same effect as opening up the stinger area at low rpm does.

[TZ350]

Frits, to your knowledge, has anyone allready tried & tested this design ?

Maybe not exactly like Frit's design but gives some idea of the possibilities. My experiment had much the same effect of increasing the chamber bleed area and lowering the residual working pressure in the chamber.

Need to click back to the original post to view all the related work.


The mid chamber bleed re visited as it might be useful for some low end boost...... Ok the mid pipe bleed didn't work for me as an over rev detonation suppressant but it did show a useful low end boost. The interesting thing was that there was very little noise from it.

286902

Red line is the bleed in the open position, Blue is closed.

286903286904

And there was those who scorned me for trying this ....... :D

I will re visit this again sometime, maybe with a bleed system like Frits suggested.

[Frits Overmars]

Frits, to your knowledge, has anyone allready tried & tested this design ?I designed this system in 2007 for Jan Thiel, who retired at the end of that same year, so the professional tests I had hoped for never took place.
After Jan and I decided to reveal our ideas, one or two tuners informed that they were going to try the moving tailpipe system, but I have no data.


My understanding of the ATAC sitting near the cylinder exit is that the stuffing pressure wave returning up the header at the wrong time ( due to the pipe length being mismatched to rpm) is reduced in amplitude when it encounters the relatively large side volume by the opened valve. Several manufacturers use this idea in concert with the power valve,in that when it is down,the Exhaust duct is connected to a volume within the sides of the cylinder via a hole in the PV drum or blade. When the PV rises,this hole is blocked of.
Killing the return wave pumps up the lower end power by reducing the pipes efficiency, exactly the same effect as opening up the stinger area at low rpm does.+1

[TZ350]

All previous discussion is about the location in the header.

The reason I’m asking is an idea about combining adjustable volume and stinger size at the end of the pipe, which would be simple to implement.

Interesting idea. Yes, when you think about it, it has all been at the header end and the benefits trumpeted by the Marketing dept. Just because it was done that way and popularized in the 70's and 80's does not mean its the only way, or even the best way.

Maybe out of phase wave disruption could be better achieved by disrupting it at the reverse cone.

....... interesting ... :niceone: ... not conventional but makes sense, thanks jannem for the ideas, you have got me thinking.

Because the reverse cone works by capturing pressure from the travailing wave and reflecting it back. Maybe disrupting the pipe action during its out of phase period would work best if the pressure in the reverse cone was not allowed to build up at all by bleeding it off into a side chamber or over sized stinger. The good thing is that unlike a conventional system with the ATAC in the header the front header/diffuser section of the pipe would still assist with scavenging if the disruption was in the reverse cone.

And maybe something like a Yamaha Exup valve could be used to open a side chamber or to activate something like Frit's idea.

<iframe width="560" height="315" src="https://www.youtube.com/embed/hcsbR4M23RI?rel=0" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen=""></iframe>

[oldjohnno]

A couple of years ago I was experimenting with different silencers in an attempt to quieten a 360 single street bike. One of the mufflers I made was a baffled design rather than an absorption type with packing; it was too loud and reduced peak power a bit though it very noticeably filled in the hole in the torque curve just under the powerband. I made the openings in the muffler a little smaller in an attempt to make it quieter and this worked to some extent but I also lost the torque it previously had under the pipe. At the time I thought the combination of a servo-operated belly bleed with a conventional rear stinger and silencer might work well but never tried it.

[Jannem]

Interesting idea. Yes, when you think about it, it has all been at the header end and the benefits trumpeted by the Marketing dept. Just because it was done that way and popularized in the 70's and 80's does not mean its the only way, or even the best way.



Packing the IP to the engine may partially also be a business decision. Protecting IP against few big engine manufacturers is better business that gazillion independent pipe builders. Having IP in the pipe may also reduce the aftermarket support and lose sales.

[Jannem]

I've got to admit I'm beginning to have heretic thoughts in this environment and wondering if there would be any value left in the 2-stroke world for IP... I'm thinking there is one aspect not directly addressed in any of these previous ideas and discussions, which would (with reasonable expectation) have a significant positive impact to the performance.

Now that I just got the ignitech, I've got to try this out.

And it's also somewhat possible, that simple crudeness of the solution will just look wrong and ridiculous for everyone when presented without the results.

[TZ350]

I've got to admit I'm beginning to have heretic thoughts in this environment.

This is definitely the place for thinking outside of the box with heretic type thoughts followed by experiments however crude.

[Jannem]

This is definitely the place for thinking outside of the box with heretic type thoughts followed by experiments however crude.
That’s definitely what this is and I’m grateful for it. This is also about open sharing of ideas, which is why I feel a little guilty about this one.
But let’s see if it even works as it should first...

[Frits Overmars]

Packing the IP to the engine may partially also be a business decision. Protecting IP against few big engine manufacturers is better business that gazillion independent pipe builders. Having IP in the pipe may also reduce the aftermarket support and lose sales.Jannem, I just re-read the last five pages and I still have no idea what IP stands for, honestly.
Remember this?
Jannem, abbreviations can easily lead to misunderstandings. When you mention a T-port, most people think of something like the yellow port below.With that T-port I could still deduce that you meant a transfer port instead of a T-shaped exhaust port. But IP? It's an Italian petrol brand (ItaliaPetroleum),
but I don't suppose you're talking about fuel and I can't think of anything else that IP could stand for. I'm all for thinking outside of the box and you may be on to something, but...
335566

[Haufen]

I thought he meant

Intellectual Property

with IP

[senso]

I'll check around.



Ha ha, no, USD70 Kitaco piston made in Japan. Chinese one wouldn't have lasted 10 tough hours.

I have been using Vertex pistons for a long time, they have some pretty nice ones for the CRM/NSR engines, large back cutout, single ring,I have ran one for 2 years(at least 900 litres of gas), always beating the snot out of the engine, what failed was the bottom end con-rod bearing.

They cost around 40€ here.

[Jannem]

I thought he meant

Intellectual Property

with IP

Yes, bad habits die hard, it seems.

[katinas]

Interesting, Suzuki used independent control for power valve and for torque chamber (ATAC) on they last years RGV 500. Very likely that they used two different servos.
Yamaha and KR3 used one shaft to control chamber and power valve at this time.

[husaberg]

Interesting, Suzuki used independent control for power valve and for torque chamber (ATAC) on they last years RGV 500. Very likely that they used two different servos.
Yamaha and KR3 used one shaft to control chamber and power valve at this time.
The later cagivas used an Atac chamber and a PV in tandem as well.
335575
The Kenny Roberts JR era Suzukis were tuned as a YZR Yamaha same pipe design etc.
This was done with Suzukis approval.
They made no more power on the dyno but they lapped seconds faster.
Pretty sure Wob mention one version of the BSL500/3 had both Atac and power valves as well.
looking at the pics of the late RGV it looks like there might have been a chamber build in to the blade PV cavity using a cavity system of atac like they used on the early RG500 road bikes mixed with their two stage blades
335577335578
The Honda beat scooter of the 80s had a foot pedal operated (to close atac chamber) The bike was ugly and looked like it was styled by Darth Vadar.They called it Vtacs

https://en.wikipedia.org/wiki/Honda_FC50
https://en.wikipedia.org/wiki/Two-stroke_power_valve_system#Honda_V-TACS

[katinas]

[QUOTE=husaberg;1131088335]The later cagivas used an Atac chamber and a PV in tandem as well.
335575
The Kenny Roberts JR era Suzukis were tuned as a YZR Yamaha same pipe design etc.
This was done with Suzukis approval.
They made no more power on the dyno but they lapped seconds faster.
Pretty sure Wob mention one version of the BSL500/3 had both Atac and power valves as well.
looking at the pics of the late RGV it looks like there might have been a chamber build in to the PV like a early RG500 road bike
335577

Thanks,
Interesting, how looks from inside KR3 cylinders. Yamaha, Honda or other way.

[husaberg]

Interesting, how looks from inside KR3 cylinders. Yamaha, Honda or other way.
the pic a was refering to was on Kenny Jrs RGV it could have a cast alloy chamber like the RG500 it looks a lot more Bulky than the earlier cylinders.
Actually it looks maybe like a seperate bolt on Cast alloy chamber?
https://www.kiwibiker.co.nz/forums/album.php?albumid=4848
Ps the round stubs on the headers are Det Buttons the cagiva had those as well as the Yamaha
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130434380#post1130434380
335581late RGV500

335584Earlier RGV500

Kenny KR3 from memory had a couple of very different engine designs
here is some stuff.
https://www.kiwibiker.co.nz/forums/album.php?albumid=5025&attachmentid=321627

other pics of RG500 Saec which is a cast in Atac system
335589335588335590

[katinas]

Second time found this cylinder, from very old Russian chainsaw "Druzba", in my friend's garage. First time, it was 30 years ago, I didn't notice anything interesting, except chromed bore. But this time ........

[Lightbulb]

Many years ago, I made a test tuned pipe that had the header geometry that we wanted. Then at the high point or parallel portion, was where the tailcone end connected. This could be moved back and forth with the engine running at around full power for adjustment. The stinger was a size that worked from other test examples , and one of the stingers had like a collet geometry on it. So it could effectively reduce the area to change the internal pipe pressure.
As it did not close uniformly it kind of looked like a garden hose connection with gaps. Yes it did what we wanted to do at the time. But for the torque aspect we found out something different that was not directly related to the pipe on the front induction model engine that increased the torque similar to moving the tail cone back. That was a large radius in the ramp of the crank shaft in the induction tract. The other aspect that effected the torque, was accidentally having a matching a stinger at 8X the diameter that created a helmholtz resonance. It was not designed that way, it was learnt after it was made.
Having the outlet hole change and getting the pressure to 95 inches of water, resulted in a better overall performing pipe, than a pipe with a larger diameter stinger that was choked down to give 95 inches of water average pressure. Adding a restrictor to the stinger size that we liked to help gain torque, did not seem to give any gain in torque that we could measure, but did reduce the power at the top end, even though it still had the 95 inches of water average pipe pressure. The response time for the pipe length change for what we were doing at the time, it was not warranted to make an adjusting tailcone length pipe. We found it was easier to just make pipes with the same header geometry, and then make different length tailcone sets, and use them. But even that was confusing on race day, so just kept with the one that made the most torque, with acceptable top end power. looking back now, we really to work on a pipe that gave us more power in the over rev side of peak that did not drop off in power as drastically as the current one does. But there is always lots of 20/20 hindsight in pipe design and research that is for sure.

[Lightbulb]

On another note, This youtube video clip is from our onboard model engine flying in circles at about 275 km/h on control lines. Not fast really, but shows the head temp in deg C. For the model engine when it stopped it got to about 218C or so, but during the run is in the 203C range. The glow plug was looking like new. Anyway just want to show what micro electronics can do, and it is a real time screen capture of an Android phone using an external WiFi aerial on the model. Here is a picture of the data board with 2 thermistor and thermocouple K type inputs, but only using 1 thermistor for the head temp from a 0.8mm glass thermistor bulb, glued with JB weld and has artic silver thermal grease down the little hole. We have a pipe with a ktype thermocouple but have run out of time testing it so far. The engine only got to the low 39k rpm. When we get it correctly sorted it should be doing in the 295 km/h speed range with the engine in the 40k rpm to 40.3k
If no one is interested in this, just remove.

https://youtu.be/ttqQS0CMO1o

335585335586335587

[Frits Overmars]

This youtube video clip is from our onboard model engine flying in circles at about 275 km/h on control lines. Not fast really, but shows the head temp in deg C.
For the model engine when it stopped it got to about 218C or so, but during the run is in the 203C range. The glow plug was looking like new.How about the glow plug temperature modulation Neil? Any news?

[Lightbulb]

Sorry Frits, just had too much trying to get this all working and fitted to a model. There is a circuit plan and another hall effect backplate made. Still have to make the new backplate data board that is adjustable to see where the timing of it needs to be etc. We have tested that on the bench we can augment the wire of the glow plug. On the bench it is difficult if it is actually doing anything, as it looks a continuous glow, bit like a filament lightbulb.
Neil

[wax]

This is the piston from my reed cylinder and some ideas from other people. i notice wobbly a while back you said to make the holes as low as possible n the skirt. Im trying to figure out why you said that and which configuration you would go with as a starting point if this was your cylinder you were setting up
thanks

[peewee]

i believe you want the piston windows low because the intake phase doesnt start until the piston is well on its way up from bdc. perhaps around TPC or even alittle later. at bdc if you put the piston windows in full view of the cylinder inlet, the windows will already be to far up the stroke by the time inlet starts. draw imaginary windows with a pencil and rotate the piston and you can see what happens. im not for sure but i think the faster the cyl pressure drops during the exh phase, the sooner the inlet phase can start.

[Frits Overmars]

We have tested that on the bench we can augment the wire of the glow plug. On the bench it is difficult if it is actually doing anything, as it looks a continuous glow, bit like a filament lightbulb.It will be a continuous glow; the thermal mass of the plug filament is much too big to expect anything else. But I think you should be able to keep the glow somewhere between red-hot and yellow-hot.

[wobbly]

+1 what peewee said.
Most engines the reeds have only just started to lift,between BDC and TPC.
What opens the reeds initially is the case going below atmospheric and the intake wave going + at the same time.
Depending upon what harmonic is active in the inlet pipe and at what rpm, the + wave can be closer to BDC or closer to TPC.
The two actions together + the rising piston dropping the case pressure opens the reeds.
Thus the lower the piston cutouts the better, and the flow requirement of the intake to make the power needed will dictate how much piston cutaway
and skirt hole area is needed.
As power rises it is first better to be looking at floor ports and or Boyesens down the side into the case, before doing the piston, as any holes create the oportunity
for destruction.
Here is a 66mm Wossner as used in my RZ400, I made the ports a little smaller as the skirts were just starting to crack at 500Km of 12,000 rpm racing.
No issue since then.

[wax]

Thank you , once again you guys have been very helpful

[Muciek]

Hey Wobbly, did You finished the engine with that special casting of the ex port?(400cc racer)

[katinas]

This is the piston from my reed cylinder and some ideas from other people. i notice wobbly a while back you said to make the holes as low as possible n the skirt. Im trying to figure out why you said that and which configuration you would go with as a starting point if this was your cylinder you were setting up
thanks

Have experience only with big Boyesens Reed Cylinders (Honda NS 250/400). Original pistons have two holes very low, but when I put the piston without any holes, mid power goes up, acceleration much better without any dip and very linear throttle response (very nice to ride), did not notice difference on top. Even without ATAC feels stronger than original pistons with ATAC. And every time when made any holes in pistons, especially on upper skirt side (cylinder with Boyesens) always was worse bottom and mid. I think, that size of cutaway on piston intake side, depends on how big Boyesens are and the holes in piston weakens flow through A B at low and mid revs.

Honda from 1980 to 1986 playing with Boyesens on CR 125 reed cylinders and piston intake side cutaway. They try bigger and smaller Boyesens, and smaller arrangement looks more like help for C than for additional suction. On first RS 125/250 with reed cylinders, they used big Boyesens, but with CR125 ended with small ones for better bottom and mid.

With Reed Cylinders without Boyesens (or with very small), there is no other way for additional mix and better flow in C, just through piston, so for more power, holes are necessary, but I do not have experience with that type of cylinders.

If your cylinder is with big Boyesens and you need mid power, would be interesting to try piston without any holes, and later try cutaways or holes in small steps and write.

Interesting, how C port influence engine power at low and mid revs. Maybe closing/opening valve on C duct, will work in simillar way like powervalve?

[TZ350]

335601

Started to make progress with a piezo amp and getting a clean usable signal. The ignition trigger pulse is on the bottom line as a marker. The just before exhaust port opening pressure peak (top line) was in the right place and of the right amplitude to be useful as an input for the Arduino. Worked well for a while then turned to mush.

I suspect the piezo crystals are getting hot and giving up. Know more tomorrow night when I try again after they have cooled down.

335602

Jaycar op amp kit KC5531 setup as a single channel and for piezo input.

[husaberg]

Started to make progress with a piezo amp and getting a clean usable signal. The ignition trigger pulse is on the bottom line as a marker. The just before exhaust port opening pressure peak (top line) was in the right place and of the right amplitude to be useful as an input for the Arduino. Worked well for a while then turned to mush.
I suspect the piezo crystals are getting hot and giving up. Know more tomorrow night when I try again after they have cooled down.
Jaycar op amp kit KC5531 setup as a single channel and for piezo input.
Rob did you know they have water cooled Piezo's they are more stabe in regards to drift.

[Norman]

Have experience only with big Boyesens Reed Cylinders (Honda NS 250/400). Original pistons have two holes very low, but when I put the piston without any holes, mid power goes up, acceleration much better without any dip and very linear throttle response (very nice to ride), did not notice difference on top. Even without ATAC feels stronger than original pistons with ATAC. And every time when made any holes in pistons, especially on upper skirt side (cylinder with Boyesens) always was worse bottom and mid. I think, that size of cutaway on piston intake side, depends on how big Boyesens are and the holes in piston weakens flow through A B at low and mid revs.

Honda from 1980 to 1986 playing with Boyesens on CR 125 reed cylinders and piston intake side cutaway. They try bigger and smaller Boyesens, and smaller arrangement looks more like help for C than for additional suction. On first RS 125/250 with reed cylinders, they used big Boyesens, but with CR125 ended with small ones for better bottom and mid.

With Reed Cylinders without Boyesens (or with very small), there is no other way for additional mix and better flow in C, just through piston, so for more power, holes are necessary, but I do not have experience with that type of cylinders.

If your cylinder is with big Boyesens and you need mid power, would be interesting to try piston without any holes, and later try cutaways or holes in small steps and write.

Interesting, how C port influence engine power at low and mid revs. Maybe closing/opening valve on C duct, will work in simillar way like powervalve?

Katinas, I find your posts about new flow paths and so on very interesting. Hopefully you will be able to do some real testing as the snow goes away..? About the "c-port powervalve", your thought is that the c-port shall be blocket up until about mid-range?

[wobbly]

Musiek, yes that has been done for a while.
The owner is very busy with a new bike shop business,but has been making cold air intakes and Titanium axles etc.
It will be on the dyno soon.

[wax]

Have experience only with big Boyesens Reed Cylinders (Honda NS 250/400). Original pistons have two holes very low, but when I put the piston without any holes, mid power goes up, acceleration much better without any dip and very linear throttle response (very nice to ride), did not notice difference on top. Even without ATAC feels stronger than original pistons with ATAC. And every time when made any holes in pistons, especially on upper skirt side (cylinder with Boyesens) always was worse bottom and mid. I think, that size of cutaway on piston intake side, depends on how big Boyesens are and the holes in piston weakens flow through A B at low and mid revs.

Honda from 1980 to 1986 playing with Boyesens on CR 125 reed cylinders and piston intake side cutaway. They try bigger and smaller Boyesens, and smaller arrangement looks more like help for C than for additional suction. On first RS 125/250 with reed cylinders, they used big Boyesens, but with CR125 ended with small ones for better bottom and mid.

With Reed Cylinders without Boyesens (or with very small), there is no other way for additional mix and better flow in C, just through piston, so for more power, holes are necessary, but I do not have experience with that type of cylinders.

If your cylinder is with big Boyesens and you need mid power, would be interesting to try piston without any holes, and later try cutaways or holes in small steps and write.

Interesting, how C port influence engine power at low and mid revs. Maybe closing/opening valve on C duct, will work in simillar way like powervalve?

Thanks for that, the boysens are not to bad on this cylinder. Interesting you found a gain with no piston holes

[chrisc]

I brought a carving blade to a gun fight back in December at the Southern Classic! Riding against 250cc 4t, 150cc 2t and 150cc 4t production bikes, I wheeled out my 1991 Honda RS50 for some fun in the twisty bits. With only 15hp, she goes alright... enough to put me 7th on a grid of 36 bikes in qualifying! This was the first race and unfortunately my GoPro failed in the next race so didn't get any video where I actually hustled a few 250s. The 3rd race I overheated the poor little thing and seized it at 143km/hr all the way to the hospital with a bruised lung hahaha. I did set the 5th fastest time overall up to when I crashed though. A 1:20.751 was my best time.

It's clear I stuffed up and overrevved the poor girl a few times at the start of the race. It was my first time riding the bike there so was still figuring out how to get it around the circuit. I'm eager to try again when she's going. I think a sub 1:20 is possible which would be faster than most the 250s.


https://youtu.be/oVQ0cPpinAA

[lodgernz]

Cool video Chris. RS125 frame I assume, but what's the engine?

[timg]

Cool video Chris. RS125 frame I assume, but what's the engine?NF4 & Derbi 50 I believe.

[husaberg]

Cool video Chris. RS125 frame I assume, but what's the engine?
Ex Honda Dave Aprilia RS50 engine isn't it?

[F5 Dave]

Derbi

Thanks Chris, I watched it all. Miss that bike.

[katinas]

Katinas, I find your posts about new flow paths and so on very interesting. Hopefully you will be able to do some real testing as the snow goes away..? About the "c-port powervalve", your thought is that the c-port shall be blocket up until about mid-range?

Yes Norman, would be interesting how engine respond with blocked C, until higher rpm, before pipe goes on and this is would be not difficult to try. If torque at mid revs rise up, then possible connect adjustable C valve to Ex PV through linkages.

Now revert my engine to rygerised shape, but very different from last year, and maybe fire it in two weeks time. So I am not sure which type try first on the road, when snow goes away. If all pieces is in place, then would be possible revert engine, from one type to other, in one day.

[katinas]

Thanks for that, the boysens are not to bad on this cylinder. Interesting you found a gain with no piston holes
First time, it was four or five years ago, when I made two 7mm holes, on std. NS 400 piston with two big holes on lower skirt side, directed upwards just below second ring in arrange with two small C ports. On the road, some engine sharpness disappeared from 6000-8000 rpm. And then I try so many different combinations, add photo with tested pistons, from last year post. But again, piston without holes work just with Boyesens, without them, maybe arrange of pistons would be in opposite way.
Even last year, when tested piston with pockets, I drill two 8mm holes (add photo),to communicate space over the small end and side piston pockets. And again, some sharpness gone. Then put plugs with 9 mm tread and power restored. Now I am scared about additional holes on pistons skirts.

Add photo of cylinders with the biggest Boyesens I ever see. Don't know engine performance capability with this cylinders, but if for some reasons reed cylinder continued exists, this type looks reliable for pistons and promising for power.

[wobbly]

What are those cylinders ?

[ceci]

https://youtu.be/XP8tmtONnGY

Solo muestro , no comento nada,

[ken seeber]

Flashy vid, but something of interest. Look at the chamber shape in the stills.

https://snowmobiles.polaris.com/en-us/snowmobile-engines/850-patriot-engine/

[SwePatrick]

Don't know engine performance capability with this cylinders, but if for some reasons reed cylinder continued exists, this type looks reliable for pistons and promising for power.

Looks like snowmobilecylinders(Rotax)?

If around 800cc they often produce around 130-140hp OEM, and a whole lot more in tuned versions, up against 180hp.

[katinas]

What are those cylinders ?

Yes, this cylinder block from SKI-DOO-ROTAX-800. Saved this photos from ebay.

[Muhr]

First time, it was four or five years ago, when I made two 7mm holes, on std. NS 400 piston with two big holes on lower skirt side, directed upwards just below second ring in arrange with two small C ports. On the road, some engine sharpness disappeared from 6000-8000 rpm. And then I try so many different combinations, add photo with tested pistons, from last year post. But again, piston without holes work just with Boyesens, without them, maybe arrange of pistons would be in opposite way.
Even last year, when tested piston with pockets, I drill two 8mm holes (add photo),to communicate space over the small end and side piston pockets. And again, some sharpness gone. Then put plugs with 9 mm tread and power restored. Now I am scared about additional holes on pistons skirts.

Add photo of cylinders with the biggest Boyesens I ever see. Don't know engine performance capability with this cylinders, but if for some reasons reed cylinder continued exists, this type looks reliable for pistons and promising for power.

Rotax max cylinders doesn't use piston windows either.335626

[SwePatrick]

I have seen good results with just a small window as high as possible underneeth the pistonring, aimed upwards into boost runner together with huge boyesens.
The port is about 6mm high and 18mm wide, aimed about 50-55 degree upwards.

But this might be because cylinder has the C-port wide open into reedhouse.
I think it helps push the mixture upwards into the short runner there is.

And if having holes lower down in piston might disturb reedpetals.
And maybe even blow away mixture that should have gone upwards into c-port, due to ejector.

A bonus is that you get some cooling effect underneeth the pistoncrown.

[peewee]

Yes, this cylinder block from SKI-DOO-ROTAX-800. Saved this photos from ebay.

that large boyesen port must make the B passage extremely short. is that no concearn ?

[katinas]

I have seen good results with just a small window as high as possible underneeth the pistonring, aimed upwards into boost runner together with huge boyesens.
The port is about 6mm high and 18mm wide, aimed about 50-55 degree upwards.

But this might be because cylinder has the C-port wide open into reedhouse.
I think it helps push the mixture upwards into the short runner there is.

And if having holes lower down in piston might disturb reedpetals.
And maybe even blow away mixture that should have gone upwards into c-port, due to ejector.

A bonus is that you get some cooling effect underneeth the pistoncrown.

Thanks, and this is why so interesting to have a deal with 2 stroke engines.

Other things, like powervalve or reed house petals seat angle, can make a difference. Honda NS cylinders is without powervalve, and some torque drop always persists around 7000 rpm, but pistons without holes eliminate this, its like with powervalve.
On the other hand, with powervalve cylinders maybe not so big difference and holes can help add some power at high revs.

[wobbly]

I have seen all manner of varying results from piston holes and Boyesens and floor ports etc etc.
But what I know now is that I can totally trust the result from the STA calculation made by EngMod.
The need for holes in the piston are totally dependent on the power ( read air flow requirement ) level being achieved.
For example the 400cc Banshee based cylinder from CPI does not need any holes at all until you approach 50 Hp ( crank ) per cylinder.
Under that and there is enough flow available thru the rising piston skirt area and Boyesens, over that and the extra flow inertia thru the reedblock
will work in concert with the piston cutouts to fill the case as is needed to make the extra power..
Things like the NS400 dont need big holes as the power level, thus bulk flow needed, is so low.

[SwePatrick]

I also think it´s depending on rpm.
The more rpm you want, the more easy you need to make it for the air to completely fill the crankhouse, even thou you have the same carb size.

[diesel62]

I have seen all manner of varying results from piston holes and Boyesens and floor ports etc etc.
But what I know now is that I can totally trust the result from the STA calculation made by EngMod.
The need for holes in the piston are totally dependent on the power ( read air flow requirement ) level being achieved.
For example the 400cc Banshee based cylinder from CPI does not need any holes at all until you approach 50 Hp ( crank ) per cylinder.
Under that and there is enough flow available thru the rising piston skirt area and Boyesens, over that and the extra flow inertia thru the reedblock
will work in concert with the piston cutouts to fill the case as is needed to make the extra power..
Things like the NS400 dont need big holes as the power level, thus bulk flow needed, is so low.So why don't KZ2 have holes in their piston?

Sent from my SM-G900F using Tapatalk

[wax]

Thats interesting you say that wobbly. I am looking to get to about 90 out of the cylinder im using. I will maybe look at cutting the skirts up to start with in the mill.
It would make a more reliable piston and hey im interested in that. We are going to the world finials in havasu and the last thing i need is a damaged piston while i am over there.
My boysen ports are small compared to the ones shown before but the cpi are closer, I will look into making my boysen ports flow better. I also notich these cylinders have a large lump in the sides by the side of the reed block. I did read before where you were talking about flow from the side of the reed and I was thinking how this may effect it

[F5 Dave]

Jeez mate! What kind of cpi barrel is that?, certainly not a Cheetah.

[wobbly]

Not sure of the reason behind such a dumbarse question,but I will bite.
A KZ2 is a case reed setup, so no flow thru the piston at all.
And yes i have tried cutting a hole thru the boost port inner duct wall to align with a slot in the piston skirt.
This worked years ago on the original Rotax tandem twin, but the TM has a much better duct entry geometry, so no free lunch there.

[diesel62]

Not sure of the reason behind such a dumbarse question,but I will bite.
A KZ2 is a case reed setup, so no flow thru the piston at all.
And yes i have tried cutting a hole thru the boost port inner duct wall to align with a slot in the piston skirt.
This worked years ago on the original Rotax tandem twin, but the TM has a much better duct entry geometry, so no free lunch there.Thanks that is where I was heading. Just didn't word correctly

Sent from my SM-P555 using Tapatalk

[peewee]

i wonder if anyone has done piston window tests on engines using methanol or nitro where there might be 2-4 times more fuel passing through the engine ?

[katinas]

I have seen all manner of varying results from piston holes and Boyesens and floor ports etc etc.
But what I know now is that I can totally trust the result from the STA calculation made by EngMod.
The need for holes in the piston are totally dependent on the power ( read air flow requirement ) level being achieved.
For example the 400cc Banshee based cylinder from CPI does not need any holes at all until you approach 50 Hp ( crank ) per cylinder.
Under that and there is enough flow available thru the rising piston skirt area and Boyesens, over that and the extra flow inertia thru the reedblock
will work in concert with the piston cutouts to fill the case as is needed to make the extra power..
Things like the NS400 dont need big holes as the power level, thus bulk flow needed, is so low.

Yes, std. NS 250/400 power level not very attractive, around 24 hp. from one cylinder on crank. Tuned versions around 30 hp. Bad thing is that this cylinders reeds house is very limited.
Some time ago, I write off this cylinders and bought TZ 250 DP4 01 02 ones for this engines, because studs mismatch with NS just 0,5 mm! And TZ barrels are very short from plane to plane, so it is possible to made 22-25mm spacer plate with big reed house. I prepare all things for this work, but suddenly, I don't know why, return to NS barrels, maybe because feels that not finished work from my racing days with Honda NS-250. I consciously restrict myself with this restricted barrels, and trying found something.

Honda NS 250 was my first Japanese motorcycle that, I bought in 1998 with Sugaya racing pipes. Engine was seized so I have no opportunity to try how it works. Prepare NS just for racing , but made some very big mistakes. It's pity, that was not two stroke man around to clear some things, at this time.
Made new pistons with holes, and modifying cylinders cooling with additional tube directly under exhaust duct (add photo of this old modified cylinder and piston), where Honda, for some unknowing reasons, left free space for air under ex duct .
The biggest mistake was compression, and this is very clear seen on piston dome and of course too much skimmed heads. Four big seize, nearly max speed, and one ended badly because of the rain, no time left to react. Later when I measured head volume, found 1:19 compression with RON 98!!! Until now I can't understand how I finished some of races, maybe additional cooling under duct help, and very rich mix. Remember, that speed was very similar to standard street Aprilia RS 250. But it was long time ago.

Maybe it's difficult to imagine, but the first Japanese motorcycle that I saw on the road in Lithuania, was around 1994, and this was Suzuki GSX-R 400

[F5 Dave]

Keep posting. I just love your passion.

[SwePatrick]

i wonder if anyone has done piston window tests on engines using methanol or nitro where there might be 2-4 times more fuel passing through the engine ?


My experiance was with methanol, i forgot to mention =)

[SwePatrick]

I also notich these cylinders have a large lump in the sides by the side of the reed block. I did read before where you were talking about flow from the side of the reed and I was thinking how this may effect it

This lump kills dead volume, good things happen =)

[acr]

Adding a 0.47mfd/200V cap across the trigger will create around 1*/1000 rpm retard.
So with around 6mm static I think it stared at 35* and by 10,000 it had 1.6mm = about 17*from memory
Thus the old pretty much straight line became a crude retarding unit, with extra mid advance for drive, and extra retard over the pipe for overev.

Wobbly is the cap an AC version or a DC cap and would a adjustable cap work to dail in the value needed

[peewee]

wob today im making new exh spigot. where it mates to the cylinder face is oval hole. do you maintain the oval shape through the spigot to the exit or you transition the oval into a round shape at the exit ?

[wobbly]

The cap I used was a Mylar ie DC type.
The value has to be fixed as you need to strobe the running system and create a reference set of marks to give you
the correct advance at one particular rpm.
On a TZ the original timing was 1.6mm and the original marks lined up at 10,000 rpm
The .47 on a TZ trigger worked the best, any bigger didnt retard any more /1000 and less gave less retard.
With the varying trigger inductance and static resistance of other model bikes, you would need to use s strobe on a variable rpm test bench like I did.

Re the add on spigot - yes transition from the oval port exit to the round header entry.

[Jannem]

Capacitance is often expressed in microfarads ufd or Mfd.
The cap you mentioned is in millifarads mfd, so 470Mfd?

Just checking as upper or lower case makes a difference. Neat trick I’d like to try.

[dutchpower]

Why lost of power

When changing blowdown data to 34
Bring it back to 31 .99 get the power back

[Haufen]

Why lost of power

When changing blowdown data to 34
Bring it back to 31 .99 get the power back

Need more info to tell you what exactly happened. Looking at the curves, I'd try 30 and then widen the port to the max in the blowdown area.

[acr]

Capacitance is often expressed in microfarads ufd or Mfd.
The cap you mentioned is in millifarads mfd, so 470Mfd?

Just checking as upper or lower case makes a difference. Neat trick I’d like to try.

0.47uf = 470nf is the same value its like kg and grams . Wobbly it looks like the mylar cap is a ac/dc cap like the main cap in the CDI units 1.0-1.5uf so there is no possitive or negative terminal on it i tried a .47uf DC cap and it moved the retard approx 10 degrees total with the + terminal conected to the trigger and - terminal to earth when i turned it around there was no reaction to the retarding i shall try a mylar type and see if the movement is the same with both types


Thank you for sharing this info Wobbly

[Jannem]

0.47uf = 470nf is the same value its like kg and grams.


Yes, the SI system is what we use here. :)
You could also express that as:
0.00047mf=0.47uf=470nf

Based on your results it sounds like .47uf is in the right ballpark.

Thanks.

[Lbracing]

Question here away from piston holes , I know the ideal rod ratio is said to be ideal around 2.1 times stroke but what if for fitment reasons I have to go upward in the 2.22 range ? Is it detrimental ?

Thanks again !

[Frits Overmars]

I know the ideal rod ratio is said to be ideal around 2.1 times stroke but what if for fitment reasons I have to go upward in the 2.22 range ? Is it detrimental ?I didn't know that.... And I'd prefer 2,2 over 2,1 :D.

[wobbly]

The mylar type cap ( 470nf )I used has no polarity, I would imagine that a polarized type would only work one way around.
I fitted the cap across the trigger wires ( inside the loom to hide it ) as most triggers are floating ( not connected to earth ).
Just to remind you - this trick is only used to make an analogue straight line ignition ( as is an old TZ ) into a retarding type.
It works by advancing the hell out of the spark at lower rpm, then retards it at a pretty much constant rate/1000 rpm.
So you need to set up a pair of reference strobe marks that align at a set rpm, then working from this base advance you can work out
what advance curve ( line ) you actually have.
As I said, the TZ350 ignition was checked by the factory as 2mm BTDC @ 10,000, but we could never run more than 1.6 when modified from stock.
From memory this was 17*, so with the mod in place I set up new marks that aligned at 17* @ 10,000.
Thus it had alot more advance before this, and less after, that increased the power dramatically, especially down low where the piston
port really struggled.

[wobbly]

Re the blowdown power loss, Dutchpower - could be any one of a hundred things that would cause that,so I have no idea.
Post the pack file so we can have a proper analysis.

[peewee]

You're joking, aren't you Peewee? Please tell me you're joking.
Methanol flow should be 16 cc per hp per minute. That's easy enough to check, but you must flow all relevant parts simultaneously, starting with the tank breather and certainly including the float valve. And if you add nitromethane, the flow requirement increases steeply, depending on the nitro percentage of course.

.

hi frits I think its just a couple weeks and the engine will run once again :wings:. I checked everything in the fuel system to make sure .

heres what I know today.

tank breather is plenty large enough
tank valve flow is 1L per 15sec
3.5mm float valve flow is .24L per 15sec
bowl capacity is .24L. its actually much more than .24L but the cylinder inlet makes the carb tilt alot forward so .24L is the limit while the bike is on level ground.

heres what I figure for full throttle fuel consumption in 15sec, which is the very most the engine will have to endure. mostly I think its over estimated to be on a safe side

delivery ratio of 1.5
525cc engine capacity
afr of 4:1
8k rpm
.001261 g/cc air density

with this numbers it seems fuel consumption will be approx .5L per 15sec. the bowl already holds .24L at minimum and the float valve will supply .24L per 15sec, atleast when its fully open. I think everything is ok. what do you think frits ?

[wobbly]

On every engine that I have changed to methanol I have used the optional float valves as supplied by Dellorto,Keihin etc.
These are always 4.2 or 4.5mm for gravity feed systems.

[Frits Overmars]

hi frits I think its just a couple weeks and the engine will run once again :wings:. I checked everything in the fuel system to make sure .
heres what I know today.
tank breather is plenty large enough
tank valve flow is 1L per 15sec
3.5mm float valve flow is .24L per 15sec
bowl capacity is .24L. its actually much more than .24L but the cylinder inlet makes the carb tilt alot forward so .24L is the limit while the bike is on level ground.
heres what I figure for full throttle fuel consumption in 15sec, which is the very most the engine will have to endure. mostly I think its over estimated to be on a safe side
delivery ratio of 1.5
525cc engine capacity
afr of 4:1
8k rpm
.001261 g/cc air density
with this numbers it seems fuel consumption will be approx .5L per 15sec. the bowl already holds .24L at minimum and the float valve will supply .24L per 15sec, atleast when its fully open. I think everything is ok. what do you think frits ?According to your data the fuel flow bottleneck is the float valve with 0,24 L per 15 sec, or 960 cc/min. That's good for 960/16 = 60 hp.
A 525 cc engine running on methanol should produce way more than 60 hp, so you're in trouble.
Don't fool yourself regarding the fuel volume in the float bowl. The fuel level will drop as soon as the engine starts to produce power; it will run leaner and leaner.
You may get lucky and reach the finish line before the engine seizes, but this is not the way to go.

[peewee]

thnx for the advice frits. wob these lectrons use mikuni float valves. 3.5mm seems to be the largest they make. I can drill out a 3.5 to a larger hole but im wondering how I could accurately recut the taper so the needle seals correctly ? maybe adegnes knows how. seems he might of drilled out his keihin float valve

[wobbly]

Trust me, a 3.5 Mikuni float valve will NEVER be enough as I have run 250cc MX engines on Meth in karts making over 60 Hp
and they absolutely for sure need the 4.5 valve as is made by Dellorto for this purpose or instant seizures is a given.
Keihin make a 4.2 for FCR on Meth.
On gravity the bowl will drain empty in no time with smaller needles.
I have had shit fights with Lectron about this over petrol carbs, and was only then I found out that they do make a " high flow " needle
that is 3.5.
I needed them for the 485 cc RZ engines I made that had over 60 Hp ( crank ) per cylinder.
Lectron were adamant that the std 3mm float would be fine - but the first run on the dyno , as it clicked 3rd gear at 8,000 the bowls were all but empty.
The 400cc RZ racebike engine has 3.5 floats on 40mm Lectrons and at full noise in 6th making 96 RWHp the level drops over 3mm.
Scary, but as it is consistent, it can be jetted reliably by having very high static levels in the bowls.
Having a bike tank sitting on top of the carbs is VERY little pressure head to keep high flow rates going - more especially when the fuel is getting low.

[TZ350]

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

Bit of Sundays Mt Wellington action, shot from a drone piloted by Wil Killip.

[pete376403]

I used a 38mm Mikuni on a 500 jawa speedway engine (four stroke, forgive me) on methanol. As far as I know the float valve was standard size but there was a horizontal slot cut between the inside of the bowl just below the valve seat. The theory was that the tapered valve flowed enough, but the bottleneck was between the triangular valve shaft and the round hole - the slot bypassed this. Whatever, the engine could run 4 laps at full throttle without starving.

[190mech]

I made a short vid of Wobbly's capacitor mod on a test bench a while back,the results can be seen;
https://www.youtube.com/watch?v=qIf4loTFeiw

[SwePatrick]

I used a 38mm Mikuni on a 500 jawa speedway engine (four stroke, forgive me) on methanol. As far as I know the float valve was standard size but there was a horizontal slot cut between the inside of the bowl just below the valve seat. The theory was that the tapered valve flowed enough, but the bottleneck was between the triangular valve shaft and the round hole - the slot bypassed this. Whatever, the engine could run 4 laps at full throttle without starving.

I use this one:
http://www.mikunioz.com/wp-content/uploads/2015/02/Mikuni-needle-valve-VM-38-11-6-hole.jpg

But i still had some issues, probably due to to much angle on the carb.

[husaberg]

I made a short vid of Wobbly's capacitor mod on a test bench a while back,the results can be seen;
https://www.youtube.com/watch?v=qIf4loTFeiw

you can add a variable one. Almost every old transistor radio has one.
As outlined here.
https://www.kiwibiker.co.nz/forums/showthread.php/142498-MB100-development?p=1130181478#post1130181478
#its in the attachments,click on them three times :)

[acr]

I made a short vid of Wobbly's capacitor mod on a test bench a while back,the results can be seen;
https://www.youtube.com/watch?v=qIf4loTFeiw

Yes 190mech i first saw your you tube video and thank you for taking the time for making and putting up the video, the the reason i started playing with this cap mod is because we have alot off the suzuki GT80l and suzuki GT80 x3 1980-1982 mod engines / bikes we have imported from Germany .The Germans have been very busy to keep the power down to 6hp and max 80kmh they have removed the piston port from the cylinder so it only has a small reed to feed the engine, the ignition on these bikes has the CDI system but with a pickup inside the flywheel but it still sparks every 180 degrees 19deg BTDC and 19deg BBDC i have marked up the flywheel with degree markings and when running from 1000rpm up to 10000rpm there is no movement at all not even a wobble , very constant at 19deg and with the Cap mod i get the same 9-10 deg retard as you did these CDI systems are very rare /exspensive used and not sold by Suzuki any more .So i buy some sets from jaycar the motorcycle CDI kit KC5466 soldered up 1 last Sunday and tried it on the Suzuki and it started and i have not moved the stator plate at all but the Jaycar CDI runs at 25 degrees advance on idle and on high rpm it goes down to around 17degrees advance then i had to play with the cap mod again it idles at 25degrees and at 2-3000rpm it goes up to 30degrees advance after that it starts to retard down to 20 degrees this was with the DC cap with the ac/dc cap little happened i will look more into it later this week so it looks like the Jaycar KC5466 is a good/better replacement for our GT80s than buying an used old CDI unit :yes:

[jbiplane]

some sets from jaycar the motorcycle CDI kit KC5466 soldered up

I tried for years different ignition solutions from known brands including
Italian Seletra, IDM
German PVL, 3W
Chez Imsoft, Vape, MZ
Belgian HPI
I used EFI solutions of Ecotrons MotoEFI Microsquirt NanoEFI and had a bunch of specific problems of components compabilities.

So finally, my team created universal EFI + ignition solution, which can use wide range of easy to get components and tune up everything from laptop including multidimensional fuel maps, ignition maps.
It can manage any 2stroke or 4stroke with any cylinder layout (inline, V, boxer ...) using the same circuit board.
It can use very different fuel pumps, fuel nozzles, ignition coils to get max of any engine. Its possible write complete engine history in logs for analyzing.
It don’t require expert knowledge to setup and operate.
We tested it for UAV (in air) and interesting to try it somethere else

[peewee]

I used a 38mm Mikuni on a 500 jawa speedway engine (four stroke, forgive me) on methanol. As far as I know the float valve was standard size but there was a horizontal slot cut between the inside of the bowl just below the valve seat. The theory was that the tapered valve flowed enough, but the bottleneck was between the triangular valve shaft and the round hole - the slot bypassed this. Whatever, the engine could run 4 laps at full throttle without starving.

heres the one I use, which appears to be the same one swepatrick uses. so you made a slot like in this pic so more fuel can go past the needle ? well I also discovered today that I don't think drilling the 3.5mm hole larger will do any good. the diam at the base of the needle taper is barely over 3.5mm. so enlarging the hole beyond 3.5 would just meen the needle would go into the hole instead of the needle taper sealing it. if that make sense

[pete376403]

It was long ago (about 35 years) but IIRC the slot was cut where I have marked in the picture. Not sure if this is the correct model carb, it had a round slide.

[Jannem]

Got the bike up and running with Ignitech and roads are beginning to melt. :) Hopefully I can soon begin to test stuff.

I just seem to come up with more wacky ideas than realistically have time to test, so here's one:banana:... 24/7 reeds have been confirmed to work, but slightly tough to implement in your garage, unless very well equipped one.
Thought about getting some very small gauge ptfe-tube which is available for transformer insulation from the Chinese web shops for peanuts and putting multi filament fishing line (which doesn't stretch much) through it. Something like .2-.3mm line can take several kg of force. Simply make tiny cables (close fit and long tubes to minimize possibility of vacuum leak), which you can fish through a small channel ground into the reed block, between the block and the carb. Epoxy tubes in place, glue line ends to the petals and use a Ignitech triggered solenoid to pull the fish home at desired rpm. :)
No return springs needed as the petals are springs themselves and the line doesn't really add any real weight to the petals.

Which gets me to the question part:

Any tips on solenoids to use with Igni not requiring extra resistors to limit current either for the box or solenoid itself?

[Muhr]

Got the bike up and running with Ignitech and roads are beginning to melt. :) Hopefully I can soon begin to test stuff.

I just seem to come up with more wacky ideas than realistically have time to test, so here's one:banana:... 24/7 reeds have been confirmed to work, but slightly tough to implement in your garage, unless very well equipped one.
Thought about getting some very small gauge ptfe-tube which is available for transformer insulation from the Chinese web shops for peanuts and putting multi filament fishing line (which doesn't stretch much) through it. Something like .2-.3mm line can take several kg of force. Simply make tiny cables (close fit and long tubes to minimize possibility of vacuum leak), which you can fish through a small channel ground into the reed block, between the block and the carb. Epoxy tubes in place, glue line ends to the petals and use a Ignitech triggered solenoid to pull the fish home at desired rpm. :)
No return springs needed as the petals are springs themselves and the line doesn't really add any real weight to the petals.

Which gets me to the question part:

Any tips on solenoids to use with Igni not requiring extra resistors to limit current either for the box or solenoid itself?



http://www.pjme.co.uk/acatalog/Aprilia_Powervalve_Parts_.html might work?

http://www.pjme.co.uk/acatalog/RS125-POWER-VALVE-SOLENOID.jpg

[Greg85]

Well finally boys and girls here is the evidence of what happens when you ceramic coat an Exhaust duct.
The duct was coated with TBC ( Thermal Barrier Coating ) by HPC as is used to coat 4T piston crowns and exhaust pipes.
It was masked off about 10mm into the duct such that the surrounding metal of the port itself would not overheat and create bore distortion.
The result is a drop of about 1Hp all the way up the front side, but more importantly the egt at lower rpm is about 50*C hotter.
From this area upward the deto level was over double that of the stock uncoated cylinder, and under normal test conditions I would have richened the jetting
to try to get back to the same deto level - obviously to the detriment of an extra power loss.
But this test shows that the actual top end jetting was all but identical.

Based on this I now firmly believe in changing the cylinder cooling regime ( TM KZ10C ) to increase the water flow under the duct, and to extend that cooling right out
to the back of the pipe spigot flange face.
I am permitted to machine say 5mm off the cylinder duct exit - and increase the flange thickness by the same amount, allowing a water passage within the fixing flange
to lengthen the cooled length of the exit flow.

i wobbly here are the crankcase335721 of the last tmkz10c black look at the picture they have machined a small part of the crankcase or there is the crankshaft to put more volume, why this place? it is not better to concentrate the volume under the transfers ? thanks

[wobbly]

There are two things in play here.TM have machined the case with enough diametric clearance between the wheels and the rod to reduce parasitic
viscous drag around the surfaces.
And the slot across the covers over the crank starting from the reed exit is there to allow flow outward of mixture trapped within the crank and the machined clearance area.
In the pic the crank spins clockwise,throwing mixture out under the piston.
It has nothing to do with increasing case volume,as I have machined 5mm off the reed mounting face, run that on the dyno and lost power.
Then I added a 5mm spacer plate, this increased power as per the stock baseline ,then I added another 5mm spacer ( making the case bigger than stock ) and lost power big time.
The reed, when fully in has no obstructions, or lift issues, and it does not compromise the boost port entry.
The engine simply does not like a case volume change - end of story.
I tried making the petals softer, to suit the bigger case, and stiffer to suit the smaller case - no free lunch to be found.
Really pissed as this test took days of work to complete with no result at all.

[wax]

There are two things in play here.TM have machined the case with enough diametric clearance between the wheels and the rod to reduce parasitic
viscous drag around the surfaces.
And the slot across the covers over the crank starting from the reed exit is there to allow flow outward of mixture trapped within the crank and the machined clearance area.
In the pic the crank spins clockwise,throwing mixture out under the piston.
It has nothing to do with increasing case volume,as I have machined 5mm off the reed mounting face, run that on the dyno and lost power.
Then I added a 5mm spacer plate, this increased power as per the stock baseline ,then I added another 5mm spacer ( making the case bigger than stock ) and lost power big time.
The reed, when fully in has no obstructions, or lift issues, and it does not compromise the boost port entry.
The engine simply does not like a case volume change - end of story.
I tried making the petals softer, to suit the bigger case, and stiffer to suit the smaller case - no free lunch to be found.
Really pissed as this test took days of work to complete with no result at all.
Ahh but any data is good data. At least you know not to bother looking there anymore.
You should have machined it 5mm shorter as you did then anodised the spacer you used to bring it back to std. Every one would have looked at the spacer and made one not knowing the intake was shorter.

[wobbly]

Ha, thats exactly what I did, we even got protested but sadly for them 1 : the rules allow intake modification 2 : we won the Nationals 3 times with that spacer in.
That was on the B model, now I run C models they all ask where the trick spacer went - I say Franco changed the case volume ( which he didnt ) to get more top end, just to add to the confusion.
PS - changing the case vol gave big differences in egt , this was when Jan had told me about making sure to rejet for any change to restore the egt to be equal.
I would have been really up the garden path if I hadnt done as he suggested.
Its completely second nature now when testing anything.

[wax]

Ha, thats exactly what I did, we even got protested but sadly for them 1 : the rules allow intake modification 2 : we won the Nationals 3 times with that spacer in.
That was on the B model, now I run C models they all ask where the trick spacer went - I say Franco changed the case volume ( which he didnt ) to get more top end, just to add to the confusion.
PS - changing the case vol gave big differences in egt , this was when Jan had told me about making sure to rejet for any change to restore the egt to be equal.
I would have been really up the garden path if I hadnt done as he suggested.
Its completely second nature now when testing anything.

I love doing that, putting something on that makes no difference to take the attention away from what you're really doing the makes the difference

[motogpdriver]

Quote Originally Posted by 190mech View Post
I made a short vid of Wobbly's capacitor mod on a test bench a while back,the results can be seen;
https://www.youtube.com/watch?v=qIf4loTFeiw

I have a question about a cdi curve testbench.
If I build 1 how can I read the ignition curve the best way?
I mean you need an rpm meter/degree disc/timing light.
is it possible to note the rpm and timing degree by eye sight or is there an other way/tool that can draw the actual curve in rpm vs degrees in let say 50rpm steps?
many thanks,

[41juergen]

Quote Originally Posted by 190mech View Post
I made a short vid of Wobbly's capacitor mod on a test bench a while back,the results can be seen;
https://www.youtube.com/watch?v=qIf4loTFeiw

I have a question about a cdi curve testbench.
If I build 1 how can I read the ignition curve the best way?
I mean you need an rpm meter/degree disc/timing light.
is it possible to note the rpm and timing degree by eye sight or is there an other way/tool that can draw the actual curve in rpm vs degrees in let say 50rpm steps?
many thanks,

That's how I build up mine CDI tester. The rpm is read via the data logger on the connected computer, the timing read via the strobe lamp. I did that for the 3XV / 4DP stuff by increasing 500 rpm each step...

335741

[Frits Overmars]

That's how I build up mine CDI tester. The rpm is read via the data logger on the connected computer, the timing read via the strobe lamp. I did that for the 3XV / 4DP stuff by increasing 500 rpm each step...Many strobe lamps are designed for about 3000 rpm and at high revs they can suffer from an unknown amount of delay, or they overheat and perish, or both.
But you don't need a strobe lamp at all.
My setup (still in Italy, alas I have no pictures of it) looked a lot like yours but instead of a degree wheel I used a nylon spool of 114,6 mm diameter with a metal measuring tape glued around it. Figure out the necessary length of tape and you'll understand.
The spool with the measuring tape was stationary, the spark plug cable was connected to the tape, and the rotating shaft carried an indicator needle that ran
close to the tape. In order to avoid the spark current from pitting the bearing races, a carbon brush made up the connection between the rotating shaft and earth.

[Michael Moore]

I need to make something to let me map the curve in the stock box on my 2015 KTM 250SX engine, since I've been unable to find that information anywhere and I suspect it may not be suitable for pavement use.

I've hopes of figuring out how to use an Arduino and sensors to capture both the RPM and the spark event, but since my small amount of programming is 30 years in the past I've got a lot to learn.

It sounds like it might also be possible to use a signal generator to trigger the box and not have to build a mechanical test bed, but electronics are magic to me since I can't see the electrons moving. I bought a digital USB o-scope but I need to get one of my EE friends to walk me through how to use it.

[Frits Overmars]

It sounds like it might also be possible to use a signal generator to trigger the box and not have to build a mechanical test bed.Provided the ignition system has a separate trigger pickup, it is very well possible to trigger the CDI via a signal generator instead of via a mechanical test bed.
That way you'll avoid the risk that the frequency regulator for the electromotor rpm will play havoc with all nearby electronics.
Frequency regulators and high-frequency welding equipment can even blow up computers. Been there...
The only remaining unknown factor when using a signal generator instead of the original pickup will be the pickup behaviour: is its trigger position rpm-independent?

[motogpdriver]

Many strobe lamps are designed for about 3000 rpm and at high revs they can suffer from an unknown amount of delay, or they overheat and perish, or both.
But you don't need a strobe lamp at all.
My setup (still in Italy, alas I have no pictures of it) looked a lot like yours but instead of a degree wheel I used a nylon spool of 114,6 mm diameter with a metal measuring tape glued around it. Figure out the necessary length of tape and you'll understand.
The spool with the measuring tape was stationary, the spark plug cable was connected to the tape, and the rotating shaft carried an indicator needle that ran
close to the tape. In order to avoid the spark current from pitting the bearing races, a carbon brush made up the connection between the rotating shaft and earth.

thank you Frits,
now I remember again,you mentioned this setup some time before:eek:
Saw something the same on youtube yesterday but at the moment can't find it again.
Still a datalogger or something like 41juergen used would be nice to draw the exact curve in degrees vs rpm.
I wonder if (without the use of a datalogger) and watch degreewheel and rpm together you can get a correct measurement?
as rpm will fluctuate from electro motor?

[wobbly]

Yes you are onto it Frits, all reluctor type triggers have a rpm dependent change in the actual " firing " point of the output ,be that a leading or trailing edge of the waveform.
ECUs compensate for this as the design of this type of trigger is pretty much universal, and they all react very similarly.
So an electronic waveform generator must be programmed to use the same rpm dependent change in the wave form crossing zero, or the results are erroneous.
I have a test bench that is simply a vacuum cleaner motor driving a secondary shaft thru a cog belt.
The variable speed is a lamp rheostat on the secondary winding of the motor - with a dpdp switch that swaps the winding's around for directional control..
And as long as you use a super cheap " inline " strobe there are no timing delays in the flash.

[wax]

Yes you are onto it Frits, all reluctor type triggers have a rpm dependent change in the actual " firing " point of the output ,be that a leading or trailing edge of the waveform.
ECUs compensate for this as the design of this type of trigger is pretty much universal, and they all react very similarly.
So an electronic waveform generator must be programmed to use the same rpm dependent change in the wave form crossing zero, or the results are erroneous.
I have a test bench that is simply a vacuum cleaner motor driving a secondary shaft thru a cog belt.
The variable speed is a lamp rheostat on the secondary winding of the motor - with a dpdp switch that swaps the winding's around for directional control..
And as long as you use a super cheap " inline " strobe there are no timing delays in the flash.
Do they also go up to a decent rpm Wobbly
I hate those things but if it works then ok

[Frits Overmars]

Do they also go up to a decent rpm Wobbly. I hate those things but if it works then okThose inline strobes don't contain any electronics, so they have zero timing delay. They are nothing more than a neon tube in series with the plug lead.
They can handle all the revs you throw at them and they are indestructible unless you drop 'm.
On the dark side, they emit only a very weak flash of light. I used to use them with a blanket covering myself and the bike in order to shut out the daylight.
That was about a century ago but sometimes I think I can still smell the smoke and the stand-off in my clothes and in my hair...

[Carel H]

This was my solution. A couple of white leds flashing at sub millisecond times at the actual ignition point. The moment you mention "time", although being minimal, for visual feedback, you know there is an error in reading. More Leds--> less flash time --> at the same time acknowledging an engine compared to a computer is a very slow thing.

[wax]

Those inline strobes don't contain any electronics and so they have zero timing delay. They are nothing more than a neon tube in series with the plug lead.
They can handle all the revs you throw at them and they are indestructible unless you drop 'm.
On the dark side, they emit only a very weak flash of light. I used to use them with a blanket covering myself and the bike in order to shut out the daylight. Sometimes I think I can still smell the smoke and the stand-off in my clothes and in my hair...
Sounds like fun. and a great way to get burnt

[Frits Overmars]

This was my solution. A couple of white leds flashing at sub millisecond times at the actual ignition point. The moment you mention "time", although being minimal, for visual feedback, you know there is an error in reading. More Leds--> less flash time --> at the same time acknowledging an engine compared to a computer is a very slow thing.I never thought of LEDs Carel. Surely they now must be cheaper than neon tubes, let alone amplified strobes. What can you tell us about their delay?

[F5 Dave]

Last week setting up my 496 RZ base advance with Ignitech. was looking good but started jumping around. Uh-oh. Which one of Wobblys commandments have I broken? .
Stood back a second to review my wiring. Then realised I'd been playing around the night before entering potential ignition and PV curves.
Course I'd forgotten about that and not put the straight 15* curve back in and it was jumping up the steep initial rise as I blipped it. :lol:

[wobbly]

Me 2 Frits, at Lake Havasu running the Jetski Worlds i had a blanket over me looking at the timing with my trusty old neon.
Then I had to use one to see the old Win 98 laptop screen as well.
The team decided as I was ugly and a cripple to boot, the blanket should remain in place wherever we went cheeky bastards.

[Matt@TYGA]

Here's what I use for bench testing. In this case it's a new one that I'm building for my NX5, so not finished yet. I have the same for the NSR250 and it works great.

I first built one so that I could simply bench test all the components of the NSR250 to check that they actually worked. Then build the basic map of the ignition, exhaust valve and air solenoid timing/curves.

It just plugs straight into the 4P connector from the pickups and I've used it many times to check various things and the best bit is the neighbours never actually know what you're up to as it's quiet as a mouse.

The rotor is driven by a simple radiator fan motor, controlled by a PWM motor controller. It'll spin up to around 12,500rpm. Not exactly the safest tool in my box, but oh well ;-)

My first box was built out of an old speaker box and some plastic hacksawed to size. The rotor was again plastic, with steel lobes screwed in. The whole arrangement balanced very scientifically......spin it up, cut a bit off or add a screw until it didn't vibrate LOL.

As for the strobe, yes this is an issue at high rpm and I've busted a couple. Oops. Rather interested in looking into the neon/xenon or LED arrangement, then I can permanently mount the light directly where it needs to be on my box.

I'll have to get some bulbs and have a play. Already have a box full of LEDs but neon/xenon bulbs are a bit thin on the ground in my toy box.

Anyway, I thought that I'd share that with you.

Matt.

[lodgernz]

I need to make something to let me map the curve in the stock box on my 2015 KTM 250SX engine, since I've been unable to find that information anywhere and I suspect it may not be suitable for pavement use.

I've hopes of figuring out how to use an Arduino and sensors to capture both the RPM and the spark event, but since my small amount of programming is 30 years in the past I've got a lot to learn.

It sounds like it might also be possible to use a signal generator to trigger the box and not have to build a mechanical test bed, but electronics are magic to me since I can't see the electrons moving. I bought a digital USB o-scope but I need to get one of my EE friends to walk me through how to use it.

Try this: https://kokoraskostas.blogspot.co.nz/2013/12/arduino-inductive-spark-plug-sensor.html

[Brett S]

I need to make something to let me map the curve in the stock box on my 2015 KTM 250SX engine, since I've been unable to find that information anywhere and I suspect it may not be suitable for pavement use.

I've hopes of figuring out how to use an Arduino and sensors to capture both the RPM and the spark event, but since my small amount of programming is 30 years in the past I've got a lot to learn.

It sounds like it might also be possible to use a signal generator to trigger the box and not have to build a mechanical test bed, but electronics are magic to me since I can't see the electrons moving. I bought a digital USB o-scope but I need to get one of my EE friends to walk me through how to use it.


Check out the BRC Racing Facebook page, Riley put up the 250 SX 2012 timing curve a few weeks back.

[Michael Moore]

Thanks Brett, the 250SX curve shown by BRC is a 2012 ignition that may be different from what my 2015 engine has but that is 1000% more information than I had before. It appears the stock ignition may not be bad at least as a starting point.

cheers,
Michael

[Jannem]

Having read here about the painstaking efforts of equalizing flow across the reed petals I came up with an idea that I decided to implement to the case I’m working on. A vertical reed channel splitter sandwhiched to the case halves between the reed and crankcase. Haven’t seen that done, but it should put the biggest pressure differentials right in the middle of the 2-petal reed openings and also direct the bulk of the flow around conrod after it has exited the reed block. I’ll post pics when I’m done, but wont test it separately as it’s pain to remove. Thought about attaching to the reed block exit and may test that in the current case, but not confident about the attachment being good enough to keep it from being digested by the engine in the long term.
Anyway, thoght I’d share fwiw.

[41juergen]

Many strobe lamps are designed for about 3000 rpm and at high revs they can suffer from an unknown amount of delay, or they overheat and perish, or both.
But you don't need a strobe lamp at all.
My setup (still in Italy, alas I have no pictures of it) looked a lot like yours but instead of a degree wheel I used a nylon spool of 114,6 mm diameter with a metal measuring tape glued around it. Figure out the necessary length of tape and you'll understand.
The spool with the measuring tape was stationary, the spark plug cable was connected to the tape, and the rotating shaft carried an indicator needle that ran
close to the tape. In order to avoid the spark current from pitting the bearing races, a carbon brush made up the connection between the rotating shaft and earth.

Frits, of course you are right. I use a strobe without any electronics and it looks like it works ok up to 12500 rpm. I had some detailed discussions with Borut from Zeeltronic how he had setup the tester he is using for his CDI development. And as I'm an mechanical engineer I went the less elecrtonical way....:laugh:

And of course physics is the same in Germany and the Netherlands (or Italy :D ) the strobe heats up and I have damaged 2 lamps trying to run the whole curve from 2000 up to 12500 rpm in one shot...:facepalm:

[wax]

Me 2 Frits, at Lake Havasu running the Jetski Worlds i had a blanket over me looking at the timing with my trusty old neon.
Then I had to use one to see the old Win 98 laptop screen as well.
The team decided as I was ugly and a cripple to boot, the blanket should remain in place wherever we went cheeky bastards.
Im off to lake Havasu this year to race the world finials in vintage wobbly

[motogpdriver]

Frits, of course you are right. I use a strobe without any electronics and it looks like it works ok up to 12500 rpm. I had some detailed discussions with Borut from Zeeltronic how he had setup the tester he is using for his CDI development. And as I'm an mechanical engineer I went the less elecrtonical way....:laugh:

And of course physics is the same in Germany and the Netherlands (or Italy :D ) the strobe heats up and I have damaged 2 lamps trying to run the whole curve from 2000 up to 12500 rpm in one shot...:facepalm:

found these:
https://www.youtube.com/watch?v=JkMFbGb6hEs

http://www.magnet-valreas.fr/style/modelisme-kart-competition/banc-allumage-karting.jpg

http://www.magnet-valreas.fr/style/modelisme-kart-competition/banc-allumage-kart.jpg

[Frits Overmars]

Me 2 Frits, at Lake Havasu running the Jetski Worlds i had a blanket over me looking at the timing with my trusty old neon. Then I had to use one to see the old Win 98 laptop screen as well. The team decided as I was ugly and a cripple to boot, the blanket should remain in place wherever we went cheeky bastards.It's a cruel world Wob. I hope you insisted on a set of custom-made company blankets :D.

[Carel H]

I never thought of LEDs Carel. Surely they now must be cheaper than neon tubes, let alone amplified strobes. What can you tell us about their delay?

Being semiconductors, they're instantaneous on and off. A quick Google search mentions nanoseconds, not microseconds. And of course you are free to use as many leds as you wish and with short pulses: overvoltage.

[Frits Overmars]

Being semiconductors, they're instantaneous on and off. A quick Google search mentions nanoseconds, not microseconds. And of course you are free to use as many leds as you wish and with short pulses: overvoltage.At 12000 rpm a 1 nanosecond delay equals a deviation of 0,000072 crankshaft degrees. I think I can live with that :D. Even a 1000 nanosecond delay would be fine.

[TZ350]

.
I have been trying to figure out a way of determining the relative air flow through my 2T motor.

From previous experience we know mass air flow meters don't work and that using the Ecotrons MAP sensor to measure the pressure in the crankcase or pipe just wound up with an average that slightly reduced below ambient as the motor came onto the pipe and flow through the motor increased.

I tried measuring the residual pressure pulse in the cylinder just before exhaust port opening. That worked well but did not tell me anything meaningful about air flow and fuelling requirements. Only whether the motor had fired or not. The best I could do with that information was to arbitrarily reduce fuel on the next cycle.

335751

My new line of thinking is to use a pressure sensor and an Arduino to determine the difference between the maximum and '
\minimum crankcase pressure each cycle and feed this value as a MAP signal to the Ecotrons EFI CPU for processing. I am picking this difference in pressures will be a good indication of mass air flow and therefor fuelling required.

335754 335753 Dyno runs taken in reducing 10% throttle position steps.

If the pressure difference idea works then I might be able to use the Volumetric efficiency VE map with the Ecotrons EFI system for the troublesome area below the 20% TPS region and the Alpha-N map for power. From experience I know that Alphan-N works well above 20% TPS.

Determining an indication of the mass air flow by finding the difference between maximum crankcase pressure as the piston descends and the minimum pressure as the pipe sucks the air/fuel mixture from the crankcase. This pressure difference must say something about the mass air flow and therefor the fuelling required, and I am guessing the pressure differential will follow the torque curve.

Hopefully, anyway if this does not work, there is always booze .... :drinkup:

[F5 Dave]

We live in the country with possibly the best Sav in the world. And for a starter maybe the best craft beer.
Yup. There's plenty to be said for drowning your sorrows.
Geez must get to the Dyno.

[SwePatrick]

.
I have been trying to figure out a way of determining the relative air flow through my 2T motor.



I had a thought when reading your post, what type of airmass sensor did you use?
Heated film or hot wire?

Why not go 'backwards' and use the older ones cars used, with a 'flap' inside that turns a potensiometer:

http://www.tav-autoverwertung.de/shop/bilder/produkte/gross/4501_1.jpg

These are almost mechanical and quite easy to build a smaller one if needed.
Thare are older japanese cars with quite small ones.
The one on picture is about 3" where you clamp the hose.

[F5 Dave]

We live in the country with possibly the best Sav in the world. And for a starter maybe the best craft beer.
Yup. There's plenty to be said for drowning your sorrows.
Geez must get to the Dyno.
Oh yeah
Panhead (Yeah I know) XPA. Fantastic.
followed by Spy Valley Sav.
With bbq smoked eye fillet steak and chicken bacon sausages
Life doesn't get much better.
Well. . Depending how the rest of the night goes. . .

[F5 Dave]

Oh. Where are my manners?

Saturday night musical interlude.

https://youtu.be/3lw6MZBmY-U

[jasonu]

And for a starter maybe the best craft beer.
.

I call bullshit on that Dave.

[F5 Dave]

I said maybe because I was a bit drunk and I haven't tried much overseas stuff lately. But beer here has improved enormously in even the last 5 years. Of course you can still get th e usual bus drivers swill, but the supermarkets carry a huge range of diverse beers as a sideline.

Well, probably not so much in Fonganui.

[wobbly]

Well here is one the you cant call bullshit in in shape or form.
Wild Earth, Central Otago, Pinot Noir - best red wine in the world at the biggest international competition.
Goes fairly well with Wakanui Brisket on the smoker for around 12 Hrs.

[ceci]

5 component completed, evolution progresses,

[jasonu]

Did somebody say brisket?????

[Flettner]

5 component completed, evolution progresses,

I've not been keeping up to date on this thread, what are we looking at here?

[ceci]

there is no thread here of this project, some of you know where this thread comes from and you know what is shown, how it works (basic concept), and what it is for

[Frits Overmars]

5 component completed, evolution progresses,
I've not been keeping up to date on this thread, what are we looking at here?
there is no thread here of this project, some of you know where this thread comes from and you know what is shown, how it works (basic concept), and what it is forSo, what about the rest of us?

[husaberg]

So, what about the rest of us?
Well Dave has vino?

[ceci]

Some of you know that it comes from a facebook page in which I have shown more photos and I have explained my ideas, this is the last 20% corresponding to the 5th component, if the one that has to avoid the loss of hydrocarbons

[ken seeber]

Some of you know that it comes from a facebook page in which I have shown more photos and I have explained my ideas, this is the last 20% corresponding to the 5th component, if the one that has to avoid the loss of hydrocarbons

Ceci, I looked up your name in FB, but I could find nothing.

It’d be nice if you could give us more details, given that your interesting design is in the public domain.

From what you have said, it appears that there is some focus on emissions and reduction, which is always good for the 2 stroke.

The cylinder appears to have 2 exhaust outlets each feeding from 2 cylinder ports, not unlike other FOS style arrangements.

The crankcase looks interesting, with what appears to be a mounting flange for an oval shaped catalytic converter. Can this be right?

Assuming I’m wrong, we’d love to have more details of the concept.

Cheers.

[katinas]

Obviously. But that is true for all piston shapes. And as the piston edge is radiused all-around, matching the combustion chamber to it is a piece of cake.

How do you figure that? A radiused piston timing edge at the transfer ports greatly promotes flow attachement to the piston dome, which does wonders for both the flow coefficient and the piston cooling.
334949

Flow from the cylinder into the transfers must of course be discouraged, so the top edges on the transfer windows must indeed be sharp. But a radiused piston top edge has very little influence on flow in that unwanted direction.
The nozzle effect that we hoped to achieve at exhaust opening, does not play a role at transfer opening because, even if the blowdown time.area has been insufficient and the cylinder pressure is still higher than the pressure in the transfer ducts, the pressure ratio will be subcritical, so the flow will be subsonic.
The benefits of a radiused piston top edge for better transfer flow into the cylinder and better piston cooling are far more important.

Friend tested KTM SX 65 radiused piston top edge and without any head matching modification, power rise 0,8 hp.

I have never seen a better school class room than this, Frits.

[wobbly]

So 0.8Hp with a piston edge radius, but where ?
Did it lose 2 Hp at another point in the powerband.

[ken seeber]

Some of you know that it comes from a facebook page in which I have shown more photos and I have explained my ideas, this is the last 20% corresponding to the 5th component, if the one that has to avoid the loss of hydrocarbons

Ceci,
It has been pointed out that the oval feature has a moving piston, so nothing to do with the catalyst. Dumb me.

So, as its movement appears to be in close phase with the piston, then it may provide some sort of extra crankcase pumping capacity, something like DKW etc have done.

Still interested.

[WilDun]

Ceci,
It has been pointed out that the oval feature has a moving piston, so nothing to do with the catalyst. Dumb me.

So, as its movement appears to be in close phase with the piston, then it may provide some sort of extra crankcase pumping capacity, something like DKW etc have done.

Still interested.

At first I did have the idea that it was the same as a diapraghm pump (but using a piston instead of a diapraghm), ie driven by crankcase pumping in order to keep the fresh charge from the crankcase.
I thought someone would explain but it seems that everyone else is in the dark as well!

Why all the mystery in the replies? - not a wind up I hope!:rolleyes:

[speedpro]

Given the evasive responses I wondered if he was related to Wobbly's mate.

[Muhr]

Friend tested KTM SX 65 radiused piston top edge and without any head matching modification, power rise 0,8 hp.

I have never seen a better school class room than this, Frits.

what did he do with blowdown / duration during the test?

[Tim Ey]

Friend tested KTM SX 65 radiused piston top edge and without any head matching modification, power rise 0,8 hp.


The main question on this topic is: Does your engine perform "better" due to the better discharge coefficent of your ports, or does it perform "better" because it has higher timings?
I'd love to see the compared dyno sheets of
-the original setup
-radiused edge
-original piston with the cylinder raised 0,25 / 0,5 / 0,8 mm.


Because what I have seen on the radiused piston topic is similar to the "piston shamrock"
as used by...
http://www.mofapower.ch/viewtopic.php?t=13366&start=1160
...basic tuners.

[katinas]

So 0.8Hp with a piston edge radius, but where ?
Did it lose 2 Hp at another point in the powerband.

Yes, it lose 1,5-2 hp at mid, add 0,8 hp on top, add 3-4 hp over peak. This tests done without any other modifications, so trans/ex duration little higher and head shape not modified for radiused piston.
All would be more clear with lowered cylinder (for same duration) and adjusted head shape/volume.
For me its very interesting too and if he do some tests again, I write something

[Frits Overmars]

Yes, it lose 1,5-2 hp at mid, add 0,8 hp on top, add 3-4 hp over peak.That can be either good or bad. I'd like to do a power range comparison. Can you post rpm-hp or rpm-kW listings of the original and the modified engine Katinas?

[ceci]

I am rookie in the forum and I will not answer as you do. Better that the images speak, being of parts of 2T engines you understand them without words335790

[Flettner]

I am rookie in the forum and I will not answer as you do. Better that the images speak, being of parts of 2T engines you understand them without words335790

does it run? or is it still just a picture.

[ceci]

does it run? or is it still just a picture.


for now it's just a picture, does it run? God and time just know it

[Flettner]

for now it's just a picture, does it run? God and time just know it

we are all rookies, no problem, speak up.

[WilDun]

"Pictures are worth 1000 words" - (that's what they say anyway) but not here! - here pictures and words always work well together...... prove that it's not just a silly guessing game.

[husaberg]

I am rookie in the forum and I will not answer as you do. Better that the images speak, being of parts of 2T engines you understand them without words

Ceci What they are asking is if you will you post a link to your facebook page?
por favor haga un enlace a disposición de su página de facebook

[Neal]

wobbly please get in touch with me .

[Neal]

So 0.8Hp with a piston edge radius, but where ?
Did it lose 2 Hp at another point in the powerband.

Wobbly please get in touch with me

[katinas]

We have some doubt about rpm., maybe this needed some dyno calibration and more practice with this new thing , but for comparison tests its no mater.

Before tests - engine Ktm SX 65 2016, cylinder tuned, head - 4,8 cc with spark plug, gasket under cylinder 0,8 mm.

1. Black: std piston, head- 4,8 cc, squash - 0,65 mm, max ign advance, RON 98.

2. Green: rounded piston (0,8 mm X 0,8 mm), no other adjustments , so head- 4,8 cc plus volume of skimmed piston material (not measured) Ron 98.

3. Red : rounded piston, head matched to piston, head volume - 4,5 cc, max ign advance, squash - 0,65 mm, Ron 102.

4. Blue: same like 3. just ignition retarded to middle point (like std).

Black and Blue very similar at mid.

Power very sensible to engine temperature, so this graphs more or less bests from all tests. Of course, would be more informative test, if Ex/Trans duration and head volume (with matched to piston) be the same like with std piston, but maybe, later after track tests.

Add my drawing graphs for quicker comparisons.

[katinas]

[QUOTE=Tim Ey;1131090210]The main question on this topic is: Does your engine perform "better" due to the better discharge coefficent of your ports, or does it perform "better" because it has higher timings?

This is the main most interesting question, but I don't know, because he did not lowered cylinder and want to try on track with this little higher timing duration.
This is not my engine and I just can say thanks for him, about this all tests info.

[Frits Overmars]

it lose 1,5-2 hp at mid, add 0,8 hp on top, add 3-4 hp over peak.
That can be either good or bad. I'd like to do a power range comparison. Can you post rpm-hp or rpm-kW listings of the original and the modified engine Katinas?
We have some doubt about rpm., maybe this needed some dyno calibration and more practice with this new thing , but for comparison tests its no matter... Add my drawing graphs for quicker comparisons.I'd really need the listings, not the graphs, for a range comparison. But your last graph is already conclusive: the red and blue curves, and the green curve when rescaled along the rpm-axis, will completely enclose the black curve.
335818

[katinas]

Frits, thank you for fine-adjustment.

[ceci]

I apologize for the inconvenience, just looking for a little motivation, to overcome a creative crisis. Having overcome it, now it's time to take care of my mental health (it would be best to turn off the personal computer and turn on the TV).
Excuse me if I'm absent for a while, I hope you understand it

[lodgernz]

335821

A 2:1 gearing without gears. Interesting...

[peewee]

hey guys ive almost finished my reducer spigot. i wanted to do a more round shape but since the spigot was a after thought, i had to maintain the roof and floor angles that were already established in the cylinder. still i think it will work ok

[F5 Dave]

I can’t believe I’m asking for foul stroke advice, but there has been some input into Fuel injection here so perhaps there are some reference sources people are aware of.

My issue is tuning my 675 triple roadbike. I’ve wideband lamba/FA Meter run though the range ninetity zillion times on the dyno & happy with how it runs with the exception of a rev range 4-5000rpm & less than 10% throttle.

I found on the inertia dyno, closed & low throttle operation was nonsensical. Possibly with a brake dyno it might give reasonable readings, but I don’t have one. I'e
Given the meter back and due to position running it on the road would likely have seen it ripped out of the pipe.

Symptoms on the road are uneven running in this rev range/throttle position/and a sudden death response to closing the throttle slightly (ok nowhere near that bad but best way to describe it).
Which turns out to be surprisingly often if you are in traffic, but you might not notice it on a spirited ride.

I’ve tried progressively richening the mixture. This seemed to fix other ranges which I'm now happy with, but I now feel like I’ve gone too far in last problem area without fixing the issue & fuel consumption now drops with every increase.

All the sites I’ve found are aimed at “Should I get my bike tuned?”/ How does fuel injection work? Not much use.

None I’ve found are aimed at tuning symptoms. Rob etc, - through your searches have you found a decent site in your quest for FI perfection??

The Triumph ECU allows 3d map changes on this older model.

[speedpro]

I've got my FZR on my rolling road which has a large disc brake and Brembo caliper. It's perfect for running it up to certain loads and rpm and setting fueling. Recently tried it with "Quick tune" on the Link G4+ and it worked Ok but a bit hard to hold an exact cell for the 3 seconds required to calculate the ratio and then automatically adjust. I have found that making manual adjustments works fine however. I've decided to relocate to a less noise-sensitive area as even only going to 10,000rpm it's a bit noisy. Max revs and full boost will certainly get the neighbour's interested. I'm using the Ecotrons ALM which works great. The test output resulted in a perfect match with the Link.

[Grumph]

I got talked into sorting a bigger/older Triumph triple while things were in flux here post quakes.

It had symptoms very like you describe, Dave. What I did find was that they seem to be very sensitive to throttle synchronisation.
And checking the base settings on the TPS was rewarding too.
So try a good old fashioned vacuum synchronisation before anything else.

[F5 Dave]

Hmm I'll recheck but can do that in TuneECU software, last time is was bang on after tiny adjustment with the screwdriver to bring one cylinder in line from near, to perfect. Injectors are matched for flow.

[husaberg]

Hmm I'll recheck but can do that in TuneECU software, last time is was bang on after tiny adjustment with the screwdriver to bring one cylinder in line from near, to perfect. Injectors are matched for flow.
could be a resonance effect with the intakes and exhausts, if it is there will be progessively smaller shadows of the same dips and gains at different revs on the dyno curve over the rev range?
If so, try what honda does and vary (in your case one of the intakes length) to mitigate.
This is why CBR400's cbr600's etc and so forth have different trumpet lengths, two long two short.
335839335840

[TZ350]

Symptoms on the road are uneven running in this rev range/throttle position/and a sudden death response to closing the throttle slightly (ok nowhere near that bad but best way to describe it). Which turns out to be surprisingly often if you are in traffic, but you might not notice it on a spirited ride.

All the sites I’ve found are aimed at “Should I get my bike tuned?”/ How does fuel injection work? Not much use. None I’ve found are aimed at tuning symptoms. Rob etc, - through your searches have you found a decent site in your quest for FI perfection??

The Triumph ECU allows 3d map changes on this older model.

The symptoms you describe are very familiar but the causes maybe different to mine. Mine are because the EFI system can't see large drops in air flow when the pipe is not sucking very hard. Or maybe our problems are similar with your system suffering from something like megaphone-its at the troublesome spot.

My engines running always improved when the length of injection covered the transfer window open time and it could run like a bag of poo if the injection timing was shorter or not at the right time. Maybe there are parallels with your inlet valve open time.

Other than basic EFI information I have not found anything on the net that goes into any real and intelligent depth.

Flettner told me that the timing of the end of injection is important on a 2T and this seems to be very true. Maybe that would be worth a look at on your bike too.

Your injection time is maybe only 40 deg at 4000 rpm 10% TP and where that injection end point happens in the total 720 degrees of a 4T cycle is going to be important too.

And the best injection end point will change with rpm, Ecotrons has a map for it. No point in firing fuel into air that is being blown back out of the inlet tract. In that case it wouldn't matter how much fuel was fired in it would mostly all get blown back out or maybe because of timing its just getting sucked straight through and blown out the exhaust and the cylinder is just left with random air fuel ratios.

Another thing to look at if enriching the map did not help, could the injector be too big. And with its minimum on time it cant be dialed down enough time wise to get into the correct air fuel range.

All injectors have a minimum on time, the trick with EFI is to run the smallest injectors possible to give yourself the widest tuning range possible. You can tell if an injector is to big because it flat lines at small throttle openings and runs rich.

[katinas]

"Rounded piston" tests with KTM SX 85 engine.

Black graph - std piston with small roundness on edge, from previous detonation.

[Grumph]

Hmm I'll recheck but can do that in TuneECU software, last time is was bang on after tiny adjustment with the screwdriver to bring one cylinder in line from near, to perfect. Injectors are matched for flow.

On some models the trigger on the cam is adjustable. Reading Rob's response reminded me as this adjustment changes injection timing. The air gap to the pickup can change response also.

[Frits Overmars]

"Rounded piston" tests with KTM SX 85 engine. Black graph - std piston with small roundness on edge, from previous detonation.Very clear results Katinas :niceone:.

[41juergen]

We have some doubt about rpm., maybe this needed some dyno calibration and more practice with this new thing , but for comparison tests its no mater.

Before tests - engine Ktm SX 65 2016, cylinder tuned, head - 4,8 cc with spark plug, gasket under cylinder 0,8 mm.

1. Black: std piston, head- 4,8 cc, squash - 0,65 mm, max ign advance, RON 98.

2. Green: rounded piston (0,8 mm X 0,8 mm), no other adjustments , so head- 4,8 cc plus volume of skimmed piston material (not measured) Ron 98.

3. Red : rounded piston, head matched to piston, head volume - 4,5 cc, max ign advance, squash - 0,65 mm, Ron 102.

4. Blue: same like 3. just ignition retarded to middle point (like std).

Black and Blue very similar at mid.

Power very sensible to engine temperature, so this graphs more or less bests from all tests. Of course, would be more informative test, if Ex/Trans duration and head volume (with matched to piston) be the same like with std piston, but maybe, later after track tests.

Add my drawing graphs for quicker comparisons.

Katinas, only to make sure: in your printouts from the dyno the temp, ambient pressure and humidity is the same for all tests. Do you have the "weather" station connected to the dyno software, does it get the actual pressure, temp and humidity for each individual run?
Thank's
Juergen

[katinas]

Katinas, only to make sure: in your printouts from the dyno the temp, ambient pressure and humidity is the same for all tests. Do you have the "weather" station connected to the dyno software, does it get the actual pressure, temp and humidity for each individual run?
Thank's
Juergen

Juergen, do not pay attention to all atmosphere parameters, they are left from previous dyno owner tests.
This tests just for comparisons and interval between Black/Green graphs - 2 hours. Red/Blue tests on second day.
All tests done until power goes down, when engine temperature reached 70-80 C.

[karter444]

Hi Wobbly
in regard to coolant flow through a kz10 engine which option do you prefer to use
a. bypass hose removed and plugged with crankcase to barrel plugs removed or
b. bypass hose fitted and crankcase to barrel plugs fitted
I see that you posted a pic of the coolant flow entering through the front of the barrel ,
is this a mod that can be done under the rules .
regards Richard

[EssexNick]

F5 Dave. Have you checked it's not something as simple as a crappy TPS?

[F5 Dave]

Thanks Nick. TPS is quite consistent in diagnostic test, can see readout as you wind it back and forward.

[lucf]

Derby readvalve engine 72cc bore 47.6 stroke 40mm
Result 32.75 hp this means 97% of Aprilia level
150m dragrace 6.62sec with total weight 130kg

If there exist a breeding ground for horsepower in motorsport, than it is the NSSC dragrace competition. Several experienced tuners prepare there engines every year to the limit close for the new season at 150 meter distance competition. The accompanying example shows that the Aprilia RSA level was almost achieved in 2017. Moreover, it was a reedvalve engine of which up to now it was assumed that approaching the power up to 3% would be impossible. Maybe we should adjust our opinion on this now! Or is it the advance of 4x cranckshaft bearing, which were not on the Aprilia RSA.

More information and pictures: https://www.deraceheldenvanweleer.nl/index.php?topic=2007.0

[jasonu]

Derby readvalve engine 72cc bore 47.6 stroke 40mm
Result 32.75 hp this means 97% of Aprilia level
150m dragrace 6.62sec with total weight 130kg

If there exist a breeding ground for horsepower in motorsport, than it is the NSSC dragrace competition. Several experienced tuners prepare there engines every year to the limit close for the new season at 150 meter distance competition. The accompanying example shows that the Aprilia RSA level was almost achieved in 2017. Moreover, it was a reedvalve engine of which up to now it was assumed that approaching the power up to 3% would be impossible. Maybe we should adjust our opinion on this now! Or is it the advance of 4x cranckshaft bearing, which were not on the Aprilia RSA.

More information and pictures: https://www.deraceheldenvanweleer.nl/index.php?topic=2007.0

https://www.facebook.com/photo.php?fbid=10208986539539779&set=pcb.10208986716384200&type=3&theater

1st link no good unless you have log in information.

[Muhr]

Derby readvalve engine 72cc bore 47.6 stroke 40mm
Result 32.75 hp this means 97% of Aprilia level
150m dragrace 6.62sec with total weight 130kg

These results raise many questions

Type of dyno crank / weel?
32.75 hp crank / weel (Bhp)?
Fuel?
Octane?
4x cranckshaft bearing?

if above is comparable, pV is startling with less than 20ms

Regards Muhr

[Jannem]

1st link no good unless you have log in information.
That and the second one doesn’t look like dyno data, what is it?

[F5 Dave]

Oh god, here we go again. Piss off.
Don't you understand? Why do you keep coming back? You should seek help.

[Frits Overmars]

More information and pictures: https://www.deraceheldenvanweleer.nl/index.php?topic=2007.0
https://www.facebook.com/photo.php?fbid=10208986539539779&set=pcb.10208986716384200&type=3&theaterThank you very much Lucf.
There is just one small problem: I cannot see that Facebook-page because Lucf has blocked me. I am not sure why, because I never wrote anything about him on Facebook. Maybe he does not want me to see what he writes about me...

I asked Jan Thiel to take a look at that Facebook-page, so he might tell me what it was all about.
Jan's answer: "I cannot see it either; Lucf has blocked me too."
I seem to remember a Ryger-argument in which Lucf publicly accused Jan Thiel of not understanding how a two-stroke works....

[jellert]

Looks like he calculated the power output using time vs distance and the weight of the bike. Fun as a little hobby MatLab project, but you can never account for every variable. So again some arbitrary calculated power curve... Also even if the 97% figure was accurate, I bet that last 3% is insanely hard to get.

Come back when you have an independent dyno result. Or don't...

[Jannem]

Suppose this is just a comparison table between RSA and given set of 72cc numbers...

https://i.imgur.com/uuhuqbT.jpg

[Vannik]

Do not confuse the sterling work of Sietse and Gerard with Luc's calculation, if you have an issue with one do not also make the other off as the same. My reading Dutch is not so good but it seems in the first post on the topic they measured on a Tovami dyno 31.9hp at 13200rpm, it made more at higher rpm but starts wheel spinning.

[Jannem]

Do not confuse the sterling work of Sietse and Gerard with Luc's calculation, if you have an issue with one do not also make the other off as the same. My reading Dutch is not so good but it seems in the first post on the topic they measured on a Tovami dyno 31.9hp at 13200rpm, it made more at higher rpm but starts wheel spinning.

I suppose you were able make that first link work to see the dyno data?

[SwePatrick]

Thank you very much Lucf.
There is just one little problem: I cannot see that Facebook-page because Lucf has blocked me. I am not sure why, because I never wrote anything about him on Facebook. Maybe he does not want me to see what he writes about me...

I asked Jan Thiel to take a look at that Facebook-page, so he might tell me what it was all about.
Jan's answer: "I cannot see it either; Lucf has blocked me too."

I seem to remember a Ryger-discussion in which Lucf accused Jan Thiel of not understanding how a two-stroke works....


He´s in 'keyboardwar' with your supposed lie about the FOS cylinder project.
He writes about he was before you etc etc.

A small person he is.....

[SwePatrick]

Enjoy!
5 minutes of portwork, still rough cutting :eek5::eek5::innocent::Punk:

https://www.youtube.com/watch?v=yyJS0EctzEY&t=200s

[wobbly]

Quote " This tests just for comparisons and interval between Black/Green graphs - 2 hours. Red/Blue tests on second day.
All tests done until power goes down, when engine temperature reached 70-80 C."
The big problem there is that a set of tests "on the second day " could easily be 3-5% wrong due to just a change in RAD.
And I know very well that the difference in power of a 125 race engine at 45*C and 65*C is over 1.5HP - going as high as 80* makes the test completely invalid.

In answer to 444, the water circuit change was a test for Franco at TM , to show that cooling the transfers first with cold water made better power.
This was part of the Exhaust duct cooling saga.
My test was trying to convince him to run the cold water (that enters the engine between the crankcase and the gearbox ) across above the mains, and into the cylinder
each side of the boost port.
The test had small drillings in the plugs under the Exhaust duct,to cool that area,and the head cover was modified with equal size slots for water entry at the front and rear.
The Tech team at Kartsport NZ have deemed the hose in the front of the cylinder as illegal.
I dont accept this ruling, as in the homologation papers there is no hose at all, thus with that logic all engines, with any hose ,must then be illegal.
And nowhere in the CIK rules does it say anything about " stock appearing ".
But I am not going to chance a protest, so I have found another way to direct the cold water back over the transfers ( keeping the small drillings as well ).

As far as LucF is concerned, I wont even comment, as I cant access any of the links.
But if he comes on here with more bullshit app generated so called "dyno " printouts,then I think he should be blocked,as he has done to many others.

[136kg136ps]

LucF replying to whether it was dyno or app .Using FB translate feature from Dutch

"Jan that is based on weight and time at the 150 meters. And I've really stayed on the thrifty side with the variable. I've been using this program since 2000 to analyze sprints when I was driving 400 m. The program was made by my son to the tudelft."

[TZ350]

.
Now that shifting premises at work has been done and things are beginning to sort out and find their new homes and life is starting to get back to normal. I can begin thinking about my EFI project again.

335874

Ok my other EFI airflow ideas have not worked out that well, but maybe the Max Min Difference thing will be the ticket.

335864

My last effort was to try and tell if the motor had fired or not and therefor how much fuel was required on the next cycle. For that I developed a pulse sensor and Arduino Nano program to look for a cylinder pressure pulse just before exhaust port opening. The concept worked Ok but it did not help that much with refining the fueling required.

335867 335868

4T's often divide the fueling into a volumetric efficiency VE map for throttle settings below 25% and an Alpha-N map for power settings.

The Alpa-N map only needs to know throttle position and rpm. Alpha-N is easy enough to get working well above 25% throttle.

A VE map requires some way of knowing what the airflow is and Automotive hot wire and flapper valve type systems don't work well on tuned 2T because of all the air reversion and fuel spit back.

For a 2T there needs to be another way to determine air flow if we want to use a VE map.

From experience I have learn't that the average pressure (Red line) does not vary much over the total power/rev range of the motor so that is pretty useless.

But there must be a maximum as the piston descends and minimum as the pipe sucks mixture from the crankcase (Black Lines).

I expect these maximum and minimum pressures to become more pronounced as airflow through the motor increases and the difference between them could be a usefull indication of air flow.

335866

My plan is to determine the Difference (Blue line) between the maximum and minimum pressure on each cycle and present it as a pseudo MAP value to the EFI CPU.

The crankcase pressure will be read by a 2.5bar MAP sensor. The Arduino will just be an interface between the MAP sensor and EFI CPU.

Why a MAP sensor and not a pressure sensor. A MAP sensor because it measures absolute pressure and can tell the EFI's CPU if the throttle is closed or the pipe is boosting air flow through the motor. A normal pressure gauge measures gauge pressure Ie., any pressure that is above atmospheric pressure.

Here is my initial code for finding the max and min values. It compiles but as yet untested. There will need to be a little extra bit of code added to match the Difference value to real world MAP numbers expected by the CPU.

The pulse from the ignition pickup is used to mark the end and start of each cycle.

It is counter intuitive that the code starts with Max=0 and Min=1024 but it becomes obvious when you think about it.


// MaxMinDifference

// Arduino Nano Routine.
// The routine is for providing a MAP value to a volumetric efficiency (VE) map for a high performance EFI 2T engine.
// By using a MAP sensor to determine the difference between Maximum and Minimum pressures in the crankcase for each cycle.
// And then calculating the Difference and outputting this as a MAP signal to the EFI's ECU.
// This difference should be a useful representation of the volume of air being drawn through the motor when at < 25% throttle opening.
// From experience, the Alpha-N methodology works well at throttle setting > 25%.
// The ignition trigger pulse is used to signal the completion of each cycle.


int CrankCasePressure = (16); // analog input pin for crankcase pressure as read by a MAP sensor.
int Maximum = 0; // Variable
int Minimum = 1023; // Variable
int Difference = 1023; // Variable
int MAPout = (17); // analog output pin for pressure difference as a MAP value to the EFI CPU.
const byte EngIgn = 2; // the number of the ignition pulsar interrupt pin.
boolean IgnPulse = false; // Boolan - using the ignition pickup pulse as a marker for a completed cycle.


void setup()
{
pinMode(16, INPUT); // initialize analog pin A3 as an input.
pinMode(17, OUTPUT); // initialize analog pin A2 as an output.
pinMode(2, INPUT); // initialize digital interupt pin D2 as an input.
analogReference(DEFAULT);
attachInterrupt(digitalPinToInterrupt(2), IgnitionPulse, RISING); // ignition pickup pulse.
}


void IgnitionPulse () {IgnPulse = true;} // we have seen a pulse from the ignition pickup.


void loop()
{do
{CrankCasePressure = analogRead(16); // read CrankCasePressure value from the MAP sensor analog input.


if (CrankCasePressure > Maximum)
{Maximum = CrankCasePressure;} // increasing high crankase pressure.


if (CrankCasePressure < Minimum)
{Minimum = CrankCasePressure;} // decreasing low crankase pressure.


Difference = Maximum - Minimum;
if (Difference > 0)
{MAPout = Difference;} // MAPout becomes an indication of air flow through the motor.


}while(IgnPulse != true); // keep looping until there is an ignition pulse.


analogWrite(17, MAPout); // pressure difference as a MAP value sent to the EFI CPU.
int Maximum = 0; // Reset the Maximum Variable so as to find the next crankcase maximum pressure.
int Minimum = 1023; // Reset the Minimum Variable so as to find the next crankcase minimum pressure.
(IgnPulse = false); // reset IgnPulse for the next cycle.
}

[katinas]

Quote " This tests just for comparisons and interval between Black/Green graphs - 2 hours. Red/Blue tests on second day.
All tests done until power goes down, when engine temperature reached 70-80 C."
The big problem there is that a set of tests "on the second day " could easily be 3-5% wrong due to just a change in RAD.
And I know very well that the difference in power of a 125 race engine at 45*C and 65*C is over 1.5HP - going as high as 80* makes the test completely invalid.


My test was trying to convince him to run the cold water (that enters the engine between the crankcase and the gearbox ) across above the mains, and into the cylinder each side of the boost port.


"Second day" tests indeed can be doubtful, but after 2 days with SX65 and 3 days with SX85 and so much dyno graphs, feels, that rounded piston, together with other head/cylinder adjustment, reach std piston mid power, better on top and very nice over revs power. Maybe track tests and words from little boy would help to understand more.

I really like your idea about outside transfers cooling, flow from crankcase all around cylinder - looks very promising.
Interesting, on NSR 250 cylinders, there is two cooling passages on each side of the C port, but as the crankcase without any holes, there is no flow in these passages (add pic).