ESE's works engine tuner

[ken seeber]

Piston edges. While the conversation is around radiussing, here’s something slightly different. A dude, who just came in today, over here is running twin KF engines that he sourced out of the UK. These run Dyke rings against the CI bore. Traditionally these just have the square edge on the land above the ring, see pic.

As these engines are not running under any rules, they came modified from the basic 4 deg crown angle. They were flat topped and the edge was chamfered as per pic. While not perfect in terms of carrying the radius to the full diameter, it does look like it would flow better, in that a sharp edge has been removed.

The head, which I haven’t actually seen, does not have any profile to follow the chamfer, but just has a matching 4 deg squish angle out to the bore diameter. This must result in an annular volume at the bore edge. It’s possibly why the piston was replaced, as it was detonated away at the top ring land area above the A/R pin.

337332337333337334.

[wobbly]

53.87mm - wow surely thats not in a 54 nominal bore ?????
And yes, having a large trapped volume in the squish/bore corner is simply asking for Mr Deto to come visit.

[katinas]

And I dont intend on spending the silly money they want for pistons or heads - far rather learn how its done myself , alot more interesting as well.

After testing full rounded piston, interesting tests was with three sharp location on piston edge: near C port and two narrow sharp edges between A and EX. Even without fully matched head, on the road feels better than with full roundness, but if you have possibilities to try this with dyno would be very nice and more clear.

Add pic - rounded piston with black spots where two C ports located

[koenich]

For the 85cc mx engines, they look like this.
Those have no rounded timing edge, rather 12° squish with a flat top - insert looks accordingly.

https://www.vhm.nl/en/catalog/engine-parts/piston-parts/piston-kits/apkt08521707a/properties/g+c+a+nr+view

[katinas]

Cylinder from 84' NSR 500 "low tank position".

[Muhr]

So. . When you are producing the gearbox version in significant numbers as a road- legal bike at a consumer product price. . . Make sure you export a bunch over here won't you? :first:

This is more of a unicorn hopefully, if I not miss something so I have to make another one. Would certainly be interesting to make a geared engine!:yes:

[TZ350]

337343
Cylinder from 84' NSR 500 "low tank position".

That is very interesting, the exhaust port bridge is fatter in the middle.

It looks like that is there to keep the area unchanged going down the duct. Not seen that before but it makes sense.

337344 Fat Ex bridge.

[190mech]

Perhaps the fat bridge has a water passage through it?

[TZ350]

.
Yes, maybe. That would make sense too. Does anyone know for sure?

[RomeuPT]

That is very interesting, the exhaust port bridge is fatter in the middle.

It looks like that is there to keep the area unchanged going down the duct. Not seen that before but it makes sense.

337344 Fat Ex bridge.

If its done no more it was/is probably not better....

[jamathi]

.
Yes, maybe. That would make sense too. Does anyone know for sure?


Yes, they have.

[husaberg]

That is very interesting, the exhaust port bridge is fatter in the middle.

It looks like that is there to keep the area unchanged going down the duct. Not seen that before but it makes sense.

337344 Fat Ex bridge.
That shape a modified teardrop is also the most efficient in terms of drag. Compared to a sharp end first.
https://i.pinimg.com/originals/75/a4/a2/75a4a2bad6530453c39f92bef4a41133.jpg (https://www.google.co.nz/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjds7SX1OPbAhWKEpQKHVUkDu8QjRx6BAgBEAU&url=https%3A%2F%2Fwww.pinterest.com%2Fpin%2F383087 512036354867%2F&psig=AOvVaw2FinTGKQpwtnojzu3um9pa&ust=1529632746749493)

[katinas]

If its done no more it was/is probably not better....

Maybe too much material exposed to hot gases, even with cooling passage. One of the head studs goes directly to Ex divider, maybe help to finish this passage. This was the first NSR 54x54,5 and claimed 142.6 hp/ 11,500 rpm.
But after more than 30 years many things changed and who knows how it works with all new things.
Massive cooling "arc" around exhaust, maybe was first steps to what we have now, con rod -104 mm (NS 500-106mm) - looks like this engine main things became basic for all later NSR/RS models.

Interesting Yamaha late 2 Ex 7 Trans ( 2001).

[Muhr]

That shape a modified teardrop is also the most efficient in terms of drag. Compared to a sharp end first.
https://i.pinimg.com/originals/75/a4/a2/75a4a2bad6530453c39f92bef4a41133.jpg (https://www.google.co.nz/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjds7SX1OPbAhWKEpQKHVUkDu8QjRx6BAgBEAU&url=https%3A%2F%2Fwww.pinterest.com%2Fpin%2F383087 512036354867%2F&psig=AOvVaw2FinTGKQpwtnojzu3um9pa&ust=1529632746749493)

Think that the problem here is that the flow speed is so high that you get flow separation even though the shape is optimized

[RomeuPT]

Maybe too much material exposed to hot gases, even with cooling passage. One of the head studs goes directly to Ex divider, maybe help to finish this passage. This was the first NSR 54x54,5 and claimed 142.6 hp/ 11,500 rpm.
But after more than 30 years many things changed and who knows how it works with all new things.
Massive cooling "arc" around exhaust, maybe was first steps to what we have now, con rod -104 mm (NS 500-106mm) - looks like this engine main things became basic for all later NSR/RS models.

Interesting Yamaha late 2 Ex 7 Trans ( 2001).


Much lower port timings on the 2001?!

[Muhr]

Think that the problem here is that the flow speed is so high that you get flow separation even though the shape is optimized

just wanted to add that blue is low pressure and red high

[RomeuPT]

Some pictures from seel cylinder.

Any idea why studs place is so high? Does it not look to have high porosity?

337350337351337352337353337354337355

[jbiplane]

Recently we made new version of 2-cylinder boxer using Yamaha RD-350 reed valves. Using carburetor without filter we saw fuel spraying out in atmosphere...

Then we make simplest experiment: install inside short tube, see red colored and problem completely disappear.

Anyone had similar experience? If no could be useful for community.

http://www.reaa.ru/cgi-bin/yabb/YaBB.pl?action=downloadfile;file=Big.jpg

http://www.reaa.ru/yabbfiles/Attachments/Small.jpg

In any case we are publishing articles in academic press and applied for invention.

[Tim Ey]

I'd put a stuffer into the RD350 reed (the cross sectional area on the bog standart reed block at its flange is ridicolously big compared to the reed opening area). And would make the connecting tubes smaller with less bend. Probably angle the reeds a bit so that they point more underneath the piston?

At the moment you got very big volume between carb and reed. And also the flow will seperate from the outside wall, hence the change in direction is too harsh.

If you change the diameter of the connecting tubes your eigenfrequency will rise --> higher "spit back" rpm.

I like your tube diode - a totaly KISS approach.

[JanBros]

Any idea why studs place is so high?

337350337351337352337353337354337355

the creator probably has experience with cylinders cracking arround low stud-holes.

[wobbly]

The stud pads are up high so that big pockets are not needed low down in the casing to enable a ring spanner onto the hex nuts.
These pockets would likely restrict the transfer duct wall positions.

Here is the interim dyno result of my cylinder testing.
The 3 port Exhaust duct exit area is reduced to my recommended 75% and the Aux duct ears are enlarged right down to the end of the spigot.
No other changes to the tune at all.
Next step is a 1.5mm radius on the IAME piston shape , and to find the correct cylinder height to use with that radius , maybe get 50 Hp for the first time.

[RomeuPT]

The stud pads are up high so that big pockets are not needed low down in the casing to enable a ring spanner onto the hex nuts.
These pockets would likely restrict the transfer duct wall positions.

Here is the interim dyno result of my cylinder testing.
The 3 port Exhaust duct exit area is reduced to my recommended 75% and the Aux duct ears are enlarged right down to the end of the spigot.
No other changes to the tune at all.
Next step is a 1.5mm radius on the IAME piston shape , and to find the correct cylinder height to use with that radius , maybe get 50 Hp for the first time.

Just that change and more then 2 hp gain, you do miracles :weird:
How you think that happens, the ears allow for much bigger exit speed of the gases on blowdown?

[Matt@TYGA]

The stud pads are up high so that big pockets are not needed low down in the casing to enable a ring spanner onto the hex nuts.
These pockets would likely restrict the transfer duct wall positions.

Here is the interim dyno result of my cylinder testing.
The 3 port Exhaust duct exit area is reduced to my recommended 75% and the Aux duct ears are enlarged right down to the end of the spigot.
No other changes to the tune at all.
Next step is a 1.5mm radius on the IAME piston shape , and to find the correct cylinder height to use with that radius , maybe get 50 Hp for the first time.

That's a pretty huge result there Wobbly. Anyway that you can cool some of the spigot to see what happens? You're probably not allowed due to silly regulations, but just in the interests of science :-)

[jonny quest]

I didn't realize how bad those kart motors are down low, 7ish hp at 8k? They must really hit hard coming on the pipe

[1948rod]

Hi in Jan 2016 nick gill posted that he was making a ex. Spigot for a parilla tag engine. Was this as successful as I imagine it would be as the original header leaves a lot to be desired. Thanks for any info.

[wobbly]

I do cool the back of the spigot Mat, with slots thru the casting into the water.
The pic is an old version done by hand as a test - also shows the smaller exit now being used in red line.
The extended Aux ducts have a huge effect on the Blowdown Cd, Jan said he saw this extra flow pattern right up the diffuser on an Aprilia pipe when it was cut open.
Cant wait to test the bigger radius piston on the new cylinder ,the insert wont match exactly at the bore as it should ,but if the power is good then I will CAD up a new one.

[katinas]

Yesterday friend tested KTM SX 65 rounded piston with sharp edge at C.
On dyno 0,4 hp more than with full roundness. Same matched head like on full rounded piston, just modified to match piston shape at C.
They even had no time to test on track , just packing all and rush to this weekend race in Poland

[F5 Dave]

I think I'm going to vomit. The amount of dyno runs I've done trying shit that didn't work and was supposed to.

[TZ350]

I think I'm going to vomit. The amount of dyno runs I've done trying shit that didn't work and was supposed to.

I hear you, sounds familiar ..... :laugh:

[TZ350]

Recently we made new version of 2-cylinder boxer using Yamaha RD-350 reed valves. Using carburetor without filter we saw fuel spraying out in atmosphere... Then we make simplest experiment: install inside short tube, see red colored and problem completely disappear.

337367

Anyone had similar experience?

Maybe similar.....

Changing the rotary valve timing did not have a beneficial affect on a blow back problem. But I got rid of the Blarrs by lengthening the inlet tract.



337364

When I first made the plenum I made it with a very short inlet. I had brought into the, shorter the better inlet idea. But this proved wrong and to be a problem. It was the source of the Blarrrs thing at 4-5,000 rpm. and I wrongly thought the inlet duration needed shortening but that had only marginal effect. Lengthening the inlet was the answer.

337363

Lengthening the inlet tract was what cured the blarrrs.

And another successful experiment was putting a divider in the inlet so one half could be closed off effectively changing the inertia and resonance to get rid of a pesky resonance hole.



337365 337366

Video of the V Tec in action http://www.youtube.com/watch?v=FeB9O6rtLXQ

[oxracer]

Some pictures from seel cylinder.

Any idea why studs place is so high? Does it not look to have high porosity?
337350337351337352337353337354337355 Hi Romeu, that cylinder has been re-plated by Racing Cylinder Services in the UK, as denoted by the RCS serial number. The other serial number starting with A denotes APTEC who are also in the UK. I've been told by my local kart tuner that RCS use a very aggressive solution for stripping the old plating off that eats certain elements out of the aluminium which leaves those tiny holes everywhere. He won't use them for that reason though I don't know if it's such a bad thing!?
Mark

[RomeuPT]

Hi Romeu, that cylinder has been re-plated by Racing Cylinder Services in the UK, as denoted by the RCS serial number. The other serial number starting with A denotes APTEC who are also in the UK. I've been told by my local kart tuner that RCS use a very aggressive solution for stripping the old plating off that eats certain elements out of the aluminium which leaves those tiny holes everywhere. He won't use them for that reason though I don't know if it's such a bad thing!?
Mark

On the transfer passages etc might be :/

This is not Langcourt you are mentioning!?

[Frits Overmars]

Some pictures from seel cylinder. Any idea why studs place is so high?That's an oldie. Later Seel cylinders had slightly lower ears with some ribbing, a power valve and auxiliary exhaust ports instead of the central bridge.
The ears on your picture were so high to prevent them from bending or breaking off, like used to happen on various Kawasaki, KTM and Honda cylinders when fitted onto too may paper gaskets by ham-fisted mechanics.
337368



I didn't realize how bad those kart motors are down low, 7ish hp at 8k? They must really hit hard coming on the pipeAny 125 cc engine making 50ish hp without the benefit of a power valve, power jet and variable ignition, is just waking up at 8 o'clock. It's the nature of the beast.
Sure, it will hit hard coming onto the pipe, but this will only be a bother if you'll allow it to drop out of the power band. That's about the first lesson you learn when operating one of those power houses: staying in the power band is safer than dropping below it and opening the throttle.



Recently we made new version of 2-cylinder boxer using Yamaha RD-350 reed valves. Using carburetor without filter we saw fuel spraying out in atmosphere...
Then we make simplest experiment: install inside short tube, see red colored and problem completely disappear.
Anyone had similar experience? If no could be useful for community. In any case we are publishing articles in academic press and applied for invention.With that short red tube you effectively created a Tesla diode.
The fuel spray you were seeing, may have been bounce-back rather than blow-back. Here is a text I wrote some time ago about the subject.
=================================================
In all inlet systems the inlet flow accelerates as long as the pressure upstream of the inlet tract is higher than the downstream pressure.
When both pressures are equal the flow has reached its maximum velocity and because mixture keeps entering the crankcase, the case pressure rises above the upstream pressure and this rising pressure gently slows the flow down to a standstill (or suddenly instead of gently if the inlet port closes too soon, which can happen in both piston port and rotary induction systems).
In any case, the pressure at the crankcase side of the inlet tract will then be higher than the pressure at the bellmouth, and mixture will start flowing back towards the free world. The extend of this backflow may be so small that it is not noticeable at the bellmouth, but it is happening nevertheless. Reed valves do it just as much as other inlet control systems.

I call this phenomenon bounce-back and it should not be confused with the blow-back that occurs when an inlet port closes too late.
Bounce-back mixture never really made it into the crankcase; it returned at the closed door.
Blown-back mixture initially entered the crankcase but then reversed its flow direction because of the rising case pressure before the case was closed.
This rising case pressure resulting in flow reversal has rather little to do with the piston moving down after TDC. It can even happen before TDC if the Helmholtz frequency of the inlet system is too high for the engine revs (low revs, big carb diameter, short inlet tract, small case volume).

By the way, bounce-back may be hardly noticeable, but on the other hand it can be even more vicious than blow-back.
As an experiment I once put a 200 mm elongation tube between the carb and the rotary inlet cover of a 125 cc Rotax.
It lowered the Helmholtz frequency of the inlet system so much that inlet flow velocity was still near its maximum when the inlet disc closed. Bounce-back was so severe that within seconds the dyno room was completely fogged up with mixture. It frightened me to death; a spark would have been enough to blow the roof off.
=================================================

[jbiplane]

Maybe similar.....
And another successful experiment was putting a divider in the inlet so one half could be closed off effectively changing the inertia and resonance to get rid of a pesky resonance hole.
Thanks, interesting input :)

[jbiplane]

With that short red tube you effectively created a Tesla diode.
The fuel spray you were seeing, may have been bounce-back rather than blow-back. Here is a text I wrote some time ago about the subject.

Hi Frits thanks fo so detailed description !!! Agreed. Will play out with intake geometry.

[peewee]

hey guys i was wondering if someone knows the reason nitro engines explode ? i figured the ign system fails to fire and a buildup of raw fuel hydraulically explodes

anyways i found a good way to richen lectron needles. just determine what spot you need more fuel . measure current thickness with calipers. mark it with red or some colored pen. grind with small diamond bit. remeasure thickness . mark with color pen again and grind as needed. works a treat. i did that procedure and now have the needle working well for 20% nitro mix with plenty of adjustment remaining so i think it can take the mix up near 40%. tomorow im testing it to see

[husaberg]

hey guys i was wondering if someone knows the reason nitro engines explode ? i figured the ign system fails to fire and a buildup of raw fuel hydraulically explodes

anyways i found a good way to richen lectron needles. just determine what spot you need more fuel . measure current thickness with calipers. mark it with red or some colored pen. grind with small diamond bit. remeasure thickness . mark with color pen again and grind as needed. works a treat. i did that procedure and now have the needle working well for 20% nitro mix with plenty of adjustment remaining so i think it can take the mix up near 40%. tomorow im testing it to see

AFAIK A lot of nitro 4t explode as the nitro contaminates the oiling system, I understand that's why a lot of drag racers run total loss oiling.

[wobbly]

Ha Ha Dave, you want to vomit - well join the club.
After the euphoria of the new cylinder duct geometry, today had to be a fail day.
The factory have made special manifolds in the past where the bottom matches the oval floor, but the roof has a big 1/2 moon step.
I took the CNC part I made that matched the entire cylinder exit face and ground out the top , into a step.FAIL
This gained a little mid, but killed the overev.

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.

All perfectly normal way to waste a day on the dyno , and have no idea what the hell is going on - yet.

[SwePatrick]

I think I'm going to vomit. The amount of dyno runs I've done trying shit that didn't work and was supposed to.

And most funny is, things that don´t work with 'this' setup might work if altering setup with a second mod or third mod........ and so on.

[JanBros]

Is there any correlation between effective transfer area and effective blowdown area ?
(effective as is flow area)

And when you do know the blowdown area, it is better to have the blowdown area at 1.5*bore distance in the exhaust duct instead of 75/90% of total exh area ?

[katinas]

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.



Similar results was on KTM sx 85, with bigger radius ( from 0.8mm to around 1.3mm). Remember, we decide not overcome 1mm. rad, but very likely, that with sharp edge on piston at C, all changes.

But really, yesterday was strange day. On NS tested piston with sharp edge at C and first time with matched head. I think it was bests results from my 3 months intensive tests. Engine pulls very hard from 10000 to 12000rpm, top left the same to 13000. But then suddenly engine lost power in third gear and stop.
First time in six years I lost one of Denso IA01 spark plug. Half of ceramic falls in to engine, but I cant say why - piston touch the head or deto or spark plug tired.

[oldjohnno]

hey guys i was wondering if someone knows the reason nitro engines explode ? i figured the ign system fails to fire and a buildup of raw fuel hydraulically explodes



The most common failure mode seems to be burnt pistons. If you watch top fuel cars go down the strip you'll notice they sometimes blow greyish smoke over the last 50m or so before they cross the line. This is vapourised aluminium from the pistons. If the piston burns right through and they're lucky they might just lose a cylinder or two but often the blower pressurises the entire crankcase with fuel/air and this ignites, possibly also igniting the fuel diluted oil in the sump. This all results in a spectacular unintended disassembly and fire.

Another common failure results from ignition of the pressurised mixture in the manifold and blower, because of a backfire or stuck or damaged intake valve or spring. When this happens the blower is usually popped right off in a brief fireball but thankfully blower restraining straps are mandatory. In the early days there were spectator deaths as a result of blowers etc. being launched into orbit and coming down in the crowd.

Hydraulic damage can occur but the big fuelers run two plugs per cylinder and two magnetos rated at 44amps each, so they can damn near light tap water.


https://www.youtube.com/watch?v=XpsN9T-bf7I

[F5 Dave]

Ha Ha Dave, you want to vomit - well join the club.
After the euphoria of the new cylinder duct geometry, today had to be a fail day.
The factory have made special manifolds in the past where the bottom matches the oval floor, but the roof has a big 1/2 moon step.
I took the CNC part I made that matched the entire cylinder exit face and ground out the top , into a step.FAIL
This gained a little mid, but killed the overev.

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.

All perfectly normal way to waste a day on the dyno , and have no idea what the hell is going on - yet.
Ok I feel a bit better.
My most notable fail was going from a bent inlet to a straight with a lot of dicking around to get the throttle to work past obstacles. It had to be better! But. .
Maybe I needed more time to try other stuff in conjunction.

[RomeuPT]

Ha Ha Dave, you want to vomit - well join the club.
After the euphoria of the new cylinder duct geometry, today had to be a fail day.
The factory have made special manifolds in the past where the bottom matches the oval floor, but the roof has a big 1/2 moon step.
I took the CNC part I made that matched the entire cylinder exit face and ground out the top , into a step.FAIL
This gained a little mid, but killed the overev.

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.

All perfectly normal way to waste a day on the dyno , and have no idea what the hell is going on - yet.

I am not sure yet what you mean or did on the piston, radius recut, is just putting a small radius on the edge and push the cylinder down to keep port timings!?

[nine-thirtysix]

Hi there.

I'm thinking right now about to change my power valve control from a mechanical govenor system to a direkt servo.
There it would be better for me out of package reasons and weight to fit a servo motor directly to the engine. May be with rubber bushing or something like that and also not with gears but with a pushrod system like RC-cars have for servos.

I haven't read or seen about anyone using anything else than a cable driven system.
Is it because these cable servos are really cheap or because a servo boltet to the engine gets ratteld apart?

And a question I came over with Ignitech is what happens with a engine without battery? Does the servo pulls out the power from the system while kicking or is the start up check time delayed?

Thanks for your answers!

[Muhr]

just wanted to add that blue is low pressure and red high
Here you have a more familiar port arrangement. Is a great difference in flow




The stud pads are up high so that big pockets are not needed low down in the casing to enable a ring spanner onto the hex nuts.
These pockets would likely restrict the transfer duct wall positions.

Here is the interim dyno result of my cylinder testing.
The 3 port Exhaust duct exit area is reduced to my recommended 75% and the Aux duct ears are enlarged right down to the end of the spigot.
No other changes to the tune at all.
Next step is a 1.5mm radius on the IAME piston shape , and to find the correct cylinder height to use with that radius , maybe get 50 Hp for the first time.

Nice result !:niceone:.. have you added material to the cylinder?

[wobbly]

As I think I said, the piston I used for the radius testing was 0.5mm higher,so with a 1mm radius on the piston edge the taller piston
had the same effect as dropping the cylinder 1/2 the radius.
This gave an increase in front side power, but killed the overev power.
Then I recut the radius to 1.5mm, this killed the midrange and gave the same power in the overev as before.
Maybe I need to try a smaller 0.75 rad - but to lower the cylinder enough I would have to then cut the base gasket face if i used stock pistons.

Re the duct geometry change in the TM cylinder.
Yes, material was added to the floor and the roof, starting at nothing where the Aux tunnels enter the main duct side, and at the other end the oval exit height was reduced by 4mm.
With the ears added on the side of the exit, this gave 76% area total.

[TZ350]

I haven't read or seen about anyone using anything else than a cable driven system.
Is it because these cable servos are really cheap or because a servo boltet to the engine gets ratteld apart?

And a question I came over with Ignitech is what happens with a engine without battery? Does the servo pulls out the power from the system while kicking or is the start up check time delayed?

We use a cable driven system because it is pretty easy/cheap to get good second hand servos, RGV, NSR, RZ etc.

We also have a push and go PV servo bike with an Ignitec DC ignition and no battery. It starts Ok, no obvious servo delay, the servo just seems to do its sweep thing once the generator starts turning over and making some power.

We modify a 150cc Lifan magneto to fit. Strip off the high voltage magneto winding's and use the 12Volt lighting winding's with a 12V voltage rectifier/regulator and a 25V/2500 uF capacitor for the DC power supply. All easy stuff to find on the net.


337384
How to make a decent light weight racing 12 Volt generator stator for the Suzuki GP/TF/TS RG50 from a Lifan after market magneto kit. We have spun these to 14,000 rpm plus on the dyno and they have proved reliable on the track.

Go to the original post to see all the "how to" details and pictures.

[peewee]

hey guys this is video from today with 30% vol. nitro mix. the tuning isn't perfect but I think its not too far off. a couple times the idle would slightly hang so I think 1/2 turn or so richen on the needle will fix that. the crankcase sounds like theres alot of excess fuel building up but once theres a load onto the engine it seems to run clean at full throttle so I think the jets are close to where they need to be. two jets are full open and the third is 1.5 turn open. ive been checking the fuel and ambient temp each riding session then recording it in a book for future reference. probly this week im planning to also buy a hydrometer and test a batch of fuel mix then see how it compares to mixing it by volume, ill report back once I have a answer to this.


https://youtu.be/odxN1fQinco

[TZ350]

.
Sounding Good!

[karter444]

The stud pads are up high so that big pockets are not needed low down in the casing to enable a ring spanner onto the hex nuts.
These pockets would likely restrict the transfer duct wall positions.

Here is the interim dyno result of my cylinder testing.
The 3 port Exhaust duct exit area is reduced to my recommended 75% and the Aux duct ears are enlarged right down to the end of the spigot.
No other changes to the tune at all.
Next step is a 1.5mm radius on the IAME piston shape , and to find the correct cylinder height to use with that radius , maybe get 50 Hp for the first time.

Hi Wobbly
during this test are the aux exhaust ports still standard or have they been ground.
Did you change the entry angle into the aux ports and did you grind any alloy from the port entry area where it turns into the aux duct passages .
re the exhaust u bend . thanks for the info way better with the short u bend and better again with an insert added
I am about to modify an existing mandrel to do the bends and hopefully can bend some 28 x 1.2 wall tube ,if they turn out ok with no tube distortion do you want a 1.2 wall bend to test
cheers Richard

[wobbly]

The Aux ports and ducts in the test cylinder were to the "factory selected " numbers but were not modified.
The ducts were changed in that they started to widen right where they intersect the
main duct , and then ended up as the big ears at the exit face.
If you change the geometry of the Aux ports at the bore, or deepen the pocket where they enter the duct, the port linking area increases and you loose almost as much power
as you gain - and the short circuiting makes it run richer.
This is due to the rear edge of the port being well past the front edge of the small end hole.
The only mod is to lift the Aux port, but again this looses mid big time, and you have to completely change the tune to get this back without loosing the overev power just gained.
Unless of course you are running Torlon small end plugs.

I have got 28 X1.2 stingers - these are made by ELTO who do the pipes.NFG as the stock TM ones are 1mm wall and this gives a greater step to the exit of the nozzle.
This works better.

[karter444]

I do cool the back of the spigot Mat, with slots thru the casting into the water.
The pic is an old version done by hand as a test - also shows the smaller exit now being used in red line.
The extended Aux ducts have a huge effect on the Blowdown Cd, Jan said he saw this extra flow pattern right up the diffuser on an Aprilia pipe when it was cut open.
Cant wait to test the bigger radius piston on the new cylinder ,the insert wont match exactly at the bore as it should ,but if the power is good then I will CAD up a new one.

Hi Wobbly
do you have a dyno result for this test barrel compared to the new barrel you have done .it would be interesting to see what and where in the curve the difference between having the duct at 75% area with the ears and having the ears with a standard duct
do both those slots go into the water jacket or are they just feed by the 2 holes at each end
cheers Richard

[wobbly]

Richard, the original duct ear tests I did were on an old KZ10 for Hamilton - that cylinder won 4 titles and with all the mods made very close power to the
Franco factory selected C cylinder shown in the dyno sheet.

With all the mods done to Kinsmans C model , it is about 1/2 way between the Franco ,and the new version just tested, but his engine result has the factory special
#5 pipe on it.
That generates a shit ton of overev, so I have retuned it to push up the front side power, as the track data shows that this is around 3/10th faster than using the extra grunt past 14,500.

But the new cylinder makes way better power everywhere than the best I can do, modifying everything in site.

Before I sent it back , I put the #5 on the new cylinder ,but that setup would be far more suitable to the very fast Euro layouts like Sarno, not goat tracks like TePuke.
DeConto and Franco are away testing exactly that right now.

The water cooling slots go right thru the flange face into water,the full length, as this cools all of the duct as well as the back of the spigot.

[TZ350]

337427 337432 All three injection ports.

Posted because someone asked what the "B" port injectors looked like.

And how much of a gap there was between the fly wheel halves.

337428 337429 337431 original Suzuki GP100 crank.

The fly wheels are 12mm further apart than standard and have been heavily skimmed on the inside faces. With the wider, slimmer flywheels and the 20mm longer Yamaha RD400 connecting rod the crankcase volume has been increased significantly.

The increased crankcase volume is there to provide as much air/fuel mixture as possible for the pipe to suck up into the cylinder in the hope of improved transfer efficiency. The pipe is designed to deliver it's suction pulse around BDC.

I am not sure what it is, but the crankcase compression ratio must be quite low compared to the traditional 1.5:1 to 1.3:1. Maybe it is as low as 1.2:1 so it relies very heavily on the pipe to draw mixture through. And with the big case volume there is plenty of mixture available. Low CC ratios seem to work better with rotary valve and piston port engines than they do with reed valve ones.

337430

The flywheels can be 12mm further apart because I fitted a 12mm spacer plate between the case halves so I could replace the 5 speed gearbox with a 6 speed one.

[TZ350]

337236

The Arduino uses a MAP sensor to measure crankcase pressure and looks for the maximum and minimum pressure and outputs the difference as a simulated MAP value to the EFI's CPU.


Too many ups and downs in the graphic. There are RPM's that are up, and RPM's that are down, close to each other, looks like a bandwith measurement problem. Try to get a datasheet of the MAP sensor, look at the response time and find out if you can take like 8-10 samples per revolution. Choose the 8-bit resolution ADC conversion off the Arduino to speed the software part up. Get rid of noise: sample deeper.

If I look at it filtered, I see the data increasing with rpm ,without significant spike.

Bandwith is just like: I want to look into this at let's say 12000 rpm, thats 200/sec, so you sample sort of valid at 2000/sec.

Thanks for the heads up.

Map sensor tech sheet says <2ms. other data sheets I have seen say 1ms so I expect it is somewhere between 1-2ms for the sensor to settle to 90% value of the change in the difference of pressure.

So not fast enough. It could easily miss the high and low point of a cycle. Certainly can't reliably make 8-10 measurements per cycle. If I can't time the measurements to be taken at predetermined points in the cycle I will have to think of something else.

337433

When I attach a large volume (50cc) to the crankcase with a small diameter hose and measure the MAP value I get a clean average reading.

I am thinking of using the average MAP reading and adding the difference between the high and low pressure each cycle as measured by a fast Piezo sensor.

That way I could maybe make 20-30 measurements per cycle even at 12,000 rpm. The Piezo would only see the relative difference between high and low but with some math it could be dialed in to show a suitable maximum amplitude.

Adding them together, average map and the piezo measured difference between the high and low pressure each cycle could give a clean pressure curve that represents mass air flow through the motor.

I am not sure how fast the Arduino Nano is, but hopefully fast enough to manage 10-20 or so readings per cycle at 12,000 rpm.

[peewee]

hey guys I have info for anyone interested. my hydrometer showed up today and I did a few tests. I still plan to mix my nitro by volume but I wanted to see how volume compared to weight and if the online charts were bullshit or not. turns out theyre not bullshit. the online chart I have says a 30% volume is about 38% by weight and that's almost dead on what I got with the hydrometer. so moral of the story, if you mix by vol, the percent by weight will by a fair bit higher. something to keep in mind

the other thing I read was, theres a chemical reaction when nitro and methanol are mixed. its true indeed. once the fuels are mixed theres a immediate temp reduction. my 30% vol mix dropped about 8.5F immediately and it was about an hour before it returned to 72F ambient temp. so to start with, the nitro was 72F, the methanol was 73.6F, once mixed it dropped to 64.5F (-8.5F). supposedly 50% mix drops the most, at nearly 15F.

unfortunatly I don't have a methanol hydrometer so I couldn't do a pretest purity test on it but I did pretest the nitro at 72F, it was 95%. my hydrometer is calibrated at 60F so that would put the nitro somewhere around 100% at 60F

after a hour or so when the fuel mix returned to ambient 72F, I put it outside at night to cool it down as close to 60F as possible, since that's where my hydrometer is calibrated. I couldn't get it much lower than about 64F so I took the reading at that temp. was 36%. which like I said before, it corresponds with online charts that say 30% vol is about 38% by weight, at the calibrated temp of the specific hydrometer. had I been able to get the fuel mix another 4F colder it would of registered about 38% on the hydrometer.

im real happy with how this old shitbox ktm has been holding up so far but I think 30%vol is as far as im going for now, atleast until I upgrade the fuel system. im afraid It may not be able to supply the float bowl sufficiently if I go any higher and I don't want to see what disaster might happen :laugh:

heres some photos
1- methanol pretest temp check
2- nitro pretest temp check
3- pretest of the 72F nitro. ( 95% )
4- temp check of the mixed fuel immediately after mixing. 64F
5- test of the fuel mix at 64F (36%). it returned to ambient 72F then it was cooled back down outside to 64F for the test

[husaberg]

im real happy with how this old shitbox ktm has been holding up so far but I think 30%vol is as far as im going for now, atleast until I upgrade the fuel system. im afraid It may not be able to supply the float bowl sufficiently if I go any higher and I don't want to see what disaster might happen :laugh:

I was thinking about your bike the other day why not plumb in a remote float bowl as well something like a SU one would work they are pretty cheap. there are plenty of different types.
337439
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over in the states there has likely been other car carbs that had remote floats as well. or just simple extensions
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its not as silly as it sounds as Mazdas used to run extended and remote flotas on tuned 13BS with IDA webbers.
http://members.ozemail.com.au/~derrwint/extfloatd.jpghttp://members.ozemail.com.au/~derrwint/extfloatb.JPG

[SwePatrick]

Or just run electronic powerjets feeded directly from fueltank.

[peewee]

whats a remote floatbowl ?

[Michael Moore]

one that isn't integral to the carb body like the SU float chamber with this AMAL GP5:

cheers,
Michael

http://www.eurospares.com/graphics/garage/ForSale/AMALGP_DSC_1676.jpg

[oldjohnno]

Or just run electronic powerjets feeded directly from fueltank.

Good idea, bypass all the damn floatbowl issues altogether.

SU floatbowls are pretty awful, they can't take much fuel pressure and don't like vibration. I've had very good results using a remote Holley bowl; they have a high flow capacity, can take at least 6psi fuel pressure and will withstand being shaken a little. I used soft rubber mounts and an additional weight to keep it steady. But if you can do without a remote bowl altogether that's ideal.

[husaberg]

Good idea, bypass all the damn floatbowl issues altogether.

SU floatbowls are pretty awful, they can't take much fuel pressure and don't like vibration. I've had very good results using a remote Holley bowl; they have a high flow capacity, can take at least 6psi fuel pressure and will withstand being shaken a little. I used soft rubber mounts and an additional weight to keep it steady. But if you can do without a remote bowl altogether that's ideal.

I was more meaning just yo have it there as a extra reserve of fuel but still plugged onto the std float bowl.
Never seen a holley remote bowl.
But they all have to be mounted so vibes dont make em worse.
Some of the Amal ones are worse than others they used to hang them off a top mount.

okay here is a pic of someone using a bodged up Holley one Yeah you are right though Su's are low pressure, probably not as available as holleys in the USA either.
http://i1195.photobucket.com/albums/aa399/Blowncbr/PowerJet_zps631eda6e.jpg

[peewee]

you saying use a float chamber from a race car holley carb ?

[speedpro]

Or just run electronic powerjets feeded directly from fueltank.A tiny FI fuel pump could feed it on demand with a simple controller to turn it off and on, Or just leave it on depending on the power supply of the bike. I used a similar idea on my methanol turbo race bike except the "powerjet" was controlled by a cast valve that could be adjusted for start by spring preload, progression by spring rate and needle taper and initial fuel flow by a standard brass jet. The fuel tank was pressurised by boost through another valve. Maybe even a small pressurised reservoir filled by the FI pump. 3bar would make a nice little jet of fuel through a fuel injector. nitro might be hard on the seals though

[Reckless]

you saying use a float chamber from a race car holley carb ?

If you want to keep it very simple?
On our meth karts we just used a car fuel filter
like this
337452

We cut them open at the top join - removed the filter then Re araldited them together.
Mounted them vertically above the carb inlet so they sat just clear of the top of the carb.
Very simple added enough reserve for the pump to catch up after a long straight.

Just adding an Idea.

[Carel H]

Thanks for the heads up.

Map sensor tech sheet says <2ms. other data sheets I have seen say 1ms so I expect it is somewhere between 1-2ms for the sensor to settle to 90% value of the change in the difference of pressure.

So not fast enough. It could easily miss the high and low point of a cycle. Certainly can't reliably make 8-10 measurements per cycle. If I can't time the measurements to be taken at predetermined points in the cycle I will have to think of something else.

337433

When I attach a large volume (50cc) to the crankcase with a small diameter hose and measure the MAP value I get a clean average reading.

I am thinking of using the average MAP reading and adding the difference between the high and low pressure each cycle as measured by a fast Piezo sensor.

That way I could maybe make 20-30 measurements per cycle even at 12,000 rpm. The Piezo would only see the relative difference between high and low but with some math it could be dialed in to show a suitable maximum amplitude.

Adding them together, average map and the piezo measured difference between the high and low pressure each cycle could give a clean pressure curve that represents mass air flow through the motor.

I am not sure how fast the Arduino Nano is, but hopefully fast enough to manage 10-20 or so readings per cycle at 12,000 rpm.

It looks like all pressure sensors (Infineon, NPX) are created equal. Full scale response 1 ms. Piezo sensors I don't know. They will have like problems as the MAP sensors: scale, size, pressure, temperature compensation etc. And they call an MAP sensor "automotive", which certainly is an advantage, in contact with fuel.

The Arduino is fast, but how fast is the program? And what are the possibilities with the compiler? I work with the exact same processor, only here it is called AVRMega and I program in assembly.

My approach for 2 measurements per revolution would be (I actually made an ignition program like this):

Have a trigger (I used a Hall sensor as ignition trigger) and use the Time Capture Pin.

If the pin is triggered then:

Calculate rpm (time now minus last revolution time).
Calculate time to TDC at this rpm and set the timer.
If the timer goes off, start ADC conversion and add half rpm now time.
If conversion is ready, read it.
Wait till the timer goes off at BDC, start conversion.
If conversion is ready, read it.

Do it again.

And of course you are free to decorate your flywheel with stickers, indicating to a dedicated sensor:

"This is where I want to start my conversion". Both versions still have the 1 ms grey area, so I would try this one first. Always nice to have a processor doing almost nothing.

I like your curiosity.

[SwePatrick]

Good idea, bypass all the damn floatbowl issues altogether.

SU floatbowls are pretty awful, they can't take much fuel pressure and don't like vibration. I've had very good results using a remote Holley bowl; they have a high flow capacity, can take at least 6psi fuel pressure and will withstand being shaken a little. I used soft rubber mounts and an additional weight to keep it steady. But if you can do without a remote bowl altogether that's ideal.

I´m going to run a electronic powerjet modded to be easily adjusted by a variable jet and electronically controlled by Ignitech.

As someone spun further on this idea with a fuelpump, i won´t try that as i recon the desired fuelflow will dynamicly adjust itself some, due to airspeed.

[TZ350]

The Arduino is fast, but how fast is the program? And what are the possibilities with the compiler? I work with the exact same processor, only here it is called AVRMega and I program in assembly.

My approach for 2 measurements per revolution would be (I actually made an ignition program like this):

Have a trigger (I used a Hall sensor as ignition trigger) and use the Time Capture Pin.

If the pin is triggered then:

Calculate rpm (time now minus last revolution time).
Calculate time to TDC at this rpm and set the timer.
If the timer goes off, start ADC conversion and add half rpm now time.
If conversion is ready, read it.
Wait till the timer goes off at BDC, start conversion.
If conversion is ready, read it.

Do it again.

"This is where I want to start my conversion". Both versions still have the 1 ms grey area, so I would try this one first. Always nice to have a processor doing almost nothing.

Great, thank you for the heads up.

It is going to be little while before the engine is backup and running so plenty of time for me to learn some more about programming. Assembly, well that will be a challenge. I hope I can get away with a high level language.

[Frits Overmars]

Assembly, well that will be a challenge. I hope I can get away with a high level language.Must be your sense of humour, TeeZee; assembly is about as low as you can get. No 'high' operating systems getting in the way and deciding what's good for you and what isn't; with assembly you talk directly to the processor. I love it. OK, I'm definitely old-school; I grew up with Algol, Fortran, Pascal and of course Basic :p.

[diesel62]

Great, thank you for the heads up.

It is going to be little while before the engine is backup and running so plenty of time for me to learn some more about programming. Assembly, well that will be a challenge. I hope I can get away with a high level language.Before it all gets to hard why don't you just put an oscilloscope on the map sensor. You will soon see if it is going to work or not.
No programming required.

Sent from my SM-P555 using Tapatalk

[lodgernz]

Must be your sense of humour, TeeZee; assembly is about as low as you can get. No 'high' operating systems getting in the way and deciding what's good for you and what isn't; with assembly you talk directly to the processor. I love it. OK, I'm definitely old-school; I grew up with Algol, Fortran, Pascal and of course Basic :p.

Actually, machine language is as low as you can get, unless you want to program the microcode in ROM. Assembler is, strictly speaking, a high-level language, but the instructions correspond pretty much one-to-one with the machine code, so it is very efficient.

C language is quite efficient though, for a HLL, so you might not need to learn assembler. It's fun of course, but a bit tedious.

TeeZee, if you do want to use assembler, PM me, I have some docs you'll need, if you don't already have them.

[TZ350]

Before it all gets to hard why don't you just put an oscilloscope on the map sensor. You will soon see if it is going to work or not.

Yes, good idea, I will try that.

Have scoped things before but the rapid changes in Frequency (read RPM) makes it hard to adjust the time base so I can see the trace properly.

It is very hard to hold the RPM steady and synch the scope. Maybe I need to work it the other way around by setting the time base for 200 Hz and then revving the bike around 12,000 RPM. That way the trace will steady up at the target point instead of continuously running to the left or right across the screen. Either way its hard work and the trace is only readable over a narrow RPM band. Synchronization becomes a continuous moving target and has me working like the proverbial one armed paper hanger.

Anyway your suggestion makes very good sense and I will try it. Maybe there are more suitable scopes ........ :scratch:

[diesel62]

I'm hearing you. Need a good quality laptop based scope not little screen old electronics scope.

Sent from my SM-P555 using Tapatalk

[TZ350]

Need a good quality laptop based scope

Tell me more. What should I look for?

[Flettner]

Frits Overmars, do you have some news on your new baby?

[diesel62]

Tell me more. What should I look for?https://www.aecs.net/products/productCategory.php?catId=2

This is what we use at work. Lots of workshops around NZ are using them. About as good as you can get
I'm not sure where you are based.

Sent from my SM-P555 using Tapatalk

[TZ350]

https://www.aecs.net/products/productCategory.php?catId=2
I'm not sure where you are based.

Auckland NZ. Great looking gear but way out of my price range but it has got me thinking, thanks.

I see there is a free sample of software to trial that can use the computers audio card. May be useful for developing the Arduino's MAP simulation software.

[Frits Overmars]

Frits Overmars, do you have some news on your new baby?Nah, waiting for a con rod that got lost in the mail, a proper ignition system and some other things. We revved it to 14.500 rpm and then opened it up for inspection. Everything looked fine, but with the present con rod I wouldn't even dream of exploring the full rpm potential.
Besides, I'm paying for the use of parts and facilities by working on a Volvo engine. I can hardly believe it myself, but seeing my buddy Jeffrey Wiesner wrestle with that lump of Swedish steel is quite rewarding.
337454 337455

[peewee]

frits i didnt know you spend your free time fixing 4t engines :laugh:

[Frits Overmars]

frits i didnt know you spend your free time fixing 4t engines :laugh:There's more in my free time that I wouldn't want you to know about, Peewee. Anyway, don't spread the word; it would ruin what's left of my reputation :p.

[wobbly]

Thats OK Frits we dont mind cross dressing 2T tuners, not so sure about those with a 4T fetish as well.

[husaberg]

Much the same ilk as KTM's GP bike injection
only for different reasons
https://www.knfilters.com/eci
https://www.knfilters.com/images/img/eci-electronic-carburetor-injection.jpg

The K&N Electronic Carburetor Injection, or ECI, is a bolt-on system that adds a supplemental fuel source to your engine. The system consists of a carb spacer plate with a fuel block and injector, an ECU, and a wide band O2 sensor. The plate has a provision for the fuel injector. When needed, the injector squirts atomized fuel into the air stream passing through the spacer plate.
In a way, the ECI system works like an EFI system that reads the air/fuel ratio fed to it from an included O2 sensor that you install in your exhaust. Where this differs from EFI, is that it is used in conjunction with the carburetor. Any time the system detects a lean condition, the injector will kick on to bring the AFR back to spec, but the engine is still fed primarily by the carb. The ECI acts as a supplement to your existing carburated setup, rather than a complete replacement system such as EFI or TBI.

[breezy]

Nah, waiting for a con rod that got lost in the mail, a proper ignition system and some other things. We revved it to 14.500 rpm and then opened it up for inspection; everything looked fine. But with the present con rod I won't even dream of exploring the full rpm potential.
Besides, I'm paying for the use of parts and facilities by working on a Volvo engine. I can hardly believe it myself, but seeing my buddy Jeffrey Wiesner wrestle with that lump of Swedish steel is quite rewarding.
337454 337455.

What are you hoping for in terms of rpm/bhp.....30000rpm... 70 bhp..

(:

[Frits Overmars]

Much the same ilk as KTM's GP bike injection only for different reasons https://www.knfilters.com/eci

the ECI system... reads the air/fuel ratio fed to it from an included O2 sensor that you install in your exhaust... Any time the system detects a lean condition, the injector will kick on to bring the AFR back to specAnd how is this system going to detect a lean condition? An O2-sensor cannot do that; it can only detect the presence of unused oxygen in the exhaust gases.
If the mixture is so rich that the engine misfires, that O2-sensor will detect O2 and then this wonderful system will enrichen the mixture even more. Been there....




Nah, waiting for a con rod that got lost in the mail, a proper ignition system and some other things. We revved it to 14.500 rpm and then opened it up for inspection. Everything looked fine, but with the present con rod I wouldn't even dream of exploring the full rpm potential.
Besides, I'm paying for the use of parts and facilities by working on a Volvo engine. I can hardly believe it myself, but seeing my buddy Jeffrey Wiesner wrestle with that lump of Swedish steel is quite rewarding.
337459 337458

What are you hoping for in terms of rpm/bhp.....30000rpm... 70 bhp..70 hp wouldn't be a problem, but 30.000 rpm might be a bit too much for a Volvo...

[katinas]

Interesting difference between RGV 500 70 and 80 degree engines.
On 70, W- reeds is partly masked the way to C on one pair of cylinders.
The last RGV, with 80 degree engine was symmetrical - free way to C on all 4. cylinders.
As I understand correctly, first time they tried W-type reed block was around 1990 on RGV 250 racer.

About rounded piston - tried it on my RGV 250 ( left sharp edge at C) and still walking with feelings that left after tests - front wheel hanging in 4 gear.

[wobbly]

Katinas, what was radius size - and did you move the cylinder ?
The un radiused C port seems to be the real trick to this, but of course if you move the cylinder then the C port timing is then " wrong " compared to
the other ports seeing the radius as effectively opening them sooner.
I want to move on and test some more, but cant see a way forward until this C port and cylinder position is clear.

[_____]

Katinas, what was radius size - and did you move the cylinder ?
I want to move on and test some more, but cant see a way forward until this C port and cylinder position is clear.
How about reducing the c port height?

[wobbly]

Yea I could do that with epoxy, as a test.
But to do it properly would involve dropping the cylinder another increment, then having to grind all the other ports up - a hideous job and ultimately not repeatably accurate.
Especially maintaining the axials.
Or secondly taking off the chrome and welding the boost port roof - again a hideous job.
Very few customers would want to spend the time ,money and effort.

[husaberg]

And how is this system going to detect a lean condition? An O2-sensor cannot do that; it can only detect the presence of unused oxygen in the exhaust gases.
If the mixture is so rich that the engine misfires, that O2-sensor will detect O2 and then this wonderful system will enrichen the mixture even more. Been there....
.
In fairness as a concept it would work better than a holley 4 barrell alone with a guy with a mullet tuning it though Frits.
The way i seen it is some idiot could still set it far to lean and it would auto correct to a correct mixture.

[husaberg]

Interesting difference between RGV 500 70 and 80 degree engines.
On 70, W- reeds is partly masked the way to C on one pair of cylinders.
The last RGV, with 80 degree engine was symmetrical - free way to C on all 4. cylinders.
As I understand correctly, first time they tried W-type reed block was around 1990 on RGV 250 racer.

About rounded piston - tried it on my RGV 250 ( left sharp edge at C) and still walking with feelings that left after tests - front wheel hanging in 4 gear.

Where did you get the drawings i have never seen those?
Yamaha went backwards and forwards heaps of times with the V angle.
On a lot of occasions it was to do with room for airbox and change with the acceptable design compromise between power and chassis design

[katinas]

Wob, this RGV engine (VJ22) was assembled 5 years ago and I rarely used it, because, ironically, concentrated on less powerful NS engine.
So I almost forget what I done on this RGV engine and before testing radiused pistons I found this:
No gasket between cylinders and block, heads original with angled sparkplug was modified - 0,7mm squash, vol 13cc., piston original flat top skimmed.
At TDC, piston top equal with cylinder top.
At BDC, piston top 0,8 mm higher than transfers lower edge, so just made 1.3mm radi on pistons with sharp edge at C location. No other modification.
So C timing left as before ( 0,8mm less than std.), just EX with A,B opens earlier but now nearly like std must be. Not measure timing, but now have electronic gauge that you recommended. Very nice thing.

And yes playing with unradiused C timing its important, so need more time, but generally very interesting at which timing "radiused" starts to overcome "sharp" power or how differs timing between "radiused" and "sharp" with equal max power.
And if "radiused" help generate more flow, then maybe bigger head volume needed.

After 3 rounds of MX 65 championships in NE zone boy left in 2nd place with radiused piston ( last round with sharp edge at C and matched head). So he have opportunity to participate in final race after 3 weeks in Czech Republic with all quickest boys from Europe. Frits, thanks again.

[katinas]

Where did you get the drawings i have never seen those?
Yamaha went backwards and forwards heaps of times with the V angle.
On a lot of occasions it was to do with room for airbox and change with the acceptable design compromise between power and chassis design

From RACERS vol.32. Other interesting thing from drawings is about EX configuration: looks like one big EX with satellites ,but maybe two big with sat. like on VJ23.
And 3 stages power valve.

Mat Oxley
https://www.motorsportmagazine.com/opinion/motogp/yamaha-motogp-bike-you-never-knew-existed
“Maybe 50 years from now…”

[husaberg]

From RACERS vol.32. Other interesting thing from drawings is about EX configuration: looks like one big EX with satellites ,but maybe two big with sat. like on VJ23.
I have yet to see a v23 port map. i looked the other day.
Suzuki and yam works bike had single and two aux EX ports back to the early 80's maybe before then they went away from them Who knows why.
Is racers a Magazine?

Wob actually made inquires about one about 4 years ago as he had herd they were a bridged twin ex port one with 2 auxs.

Edit 6 years ago

Have just found out that the Suzuki VJ23 cylinder is a T port ( like the older models and also Aprilia RS250) but it has sub ports as well.
This may be an even better choice for sitting on a RG bottom end and sleeving to 50mm.
Anyone got one I can look at.

[F5 Dave]

Yeah that's right. A mate has one (currently in his kitchen, no room in lounge for RZ500). Forgot to take a pic bit bridged with 2 aux. Odd. Also barrel seated twisted in relationship to crank a little.

[Flettner]

Ok, Rob, time to abandon that ecotrons bull shit.

Link is an NZ based company that has been in the EFI business for years. Their tech guys are readily available (during business hours) and very knowledgeable. I use the link ECU and without their input I would not have been able to bring the YZ 250 TPI to success. Yes their units are expensive but in my opinion well worth the outlay, if nothing else in terms of help over the phone.
I also use a company call EFI NZ, will sell you any thing EFI sensors, injectors etc, all good quality stuff. I just bought a tiny nippon denso fuel pump, ethanol capable as an example.
And I use a guy in Tauranga, Dave, at DTECH. Knows the Link ECU inside out, but not for free. He is helping me with my 360 mark two TPI.
Don't battle with people (ecotrons) that are only intetested in money and don't want to help.

[TZ350]

.
Hi Flettner, thanks for that, it is very tempting.

:brick:

Because it has been another frustrating few days banging my head trying to get some simple help from the Ecotrons support team.

All I want is for the VE table in my EFI software to be turned on, how hard can that be.

I have no doubt these Ecotrons guys are really really smart pointy heads when building EFI systems but are so totally inept and completely shit to deal with when it comes to simple support for their product.

I am not looking for them to solve my tuning issues. I just need them to flick the secret switch that allows my CPU to run both Alpa-N and VE volumetric efficiency maps. The software is there, it is just a switch flick that is a normal part of other brands of EFI software.

I have posted my 2T EFI adventures and persevered with Ecotrons because it is easily affordable for myself and anyone else who might like to experiment with 2T EFI too.

But as much as I like Ecotrons hardware I am seriously looking to kick Ecotrons to touch because their poor support makes it so hard to work with.

And today following Flettners suggestion I had a chat with the Link support team, great bunch of enthusiastic guys. Easy to talk with and very helpful.

The quality of Link's support team is making a Link G4+ look very attractive.

I put a proposal to Ecotrons and will wait a few days to see their response, if its not helpful I will be binning their system which is pretty useless without cooperative help for the simple but important things.

[katinas]

Yeah that's right. A mate has one (currently in his kitchen, no room in lounge for RZ500). Forgot to take a pic bit bridged with 2 aux. Odd. Also barrel seated twisted in relationship to crank a little.

Kawasaki used it on KX 125 in 1986. VJ23 aux looks modest, but maybe with bigger main EX.
Interesting staggered reed cage of RSW 250, partly to copy crank web.

[katinas]

Few days thinking about 2000 Estonian Tallin TT event, exactly 18 years ago.
We arrived late on friday at the end of fist 125/250 training. I was pushing my bike to tech inspection when they return from track and suddenly stopped in thinking where I see this helmet before. I turned and can't believed, it was Joey Dunlop.
On saturday he wining everything on four strokes, it was amazing how nice was his riding style.
On Sunday it was veterans race, some drizzle before start and doubts about tires. After first 2 laps Joey on RS 125 and Lembitt Tessalu ( add photo) on TZ 250 was in front. They always battle - after straights before corners, Tesallu was at the front, but after exit Joey see clear track. This always repeat at corner where I was standing.
All ended at very fast left hand on full gas before main straight with trees all around.
Still remember saturday evening, when Joey was siting in folding chair with some drink in hand and his eyes wandering somewhere between trees. Estonian TT was like old style GP, vans, tents, all riders together in the forest, amazing atmosphere.

My own race ended after warm up lap before race, when engine lost some power. At the morning training engine seized at fastest place on start finish line and I was very busy with restoring everything in time, at the same time trying to resolve cdi problems on mate RG 250 and simply forget to fill the water in to my NS 250 before race. So with 1:19 compression on 98 RON and without cooling, engine said enough after more than 6 km first warm up lap, but not seized.

Estonians and Latvians always be very clever about 2T and was fastest when we where isolated from all world in s... union. Estonians produce "Vihur "road racing motorcycles with CZ, Rotax and Yamaha engines and Latvians Riga mainly 50cc. But most racers deal with useless Iz, Minsk, Kovrov engines, they simply made miracles extracting impossible powers. So much energy to such bad engines. There was one class only for womens, with 175cc Kovrov 1 cylinder engine.
Most interesting was racers from Cuba. They arrived from airport to tracks with suitcases full of metal and assembled motorcycle in 1 hour or so, mainly with CZ cross engines adapted to road racing. It was amazing.

Add video Estonian Tallin TT 1958 https://www.youtube.com/watch?v=eLLjkogKZxE
Track was used from 1933 until 2006 motorcycle race but was abandoned due to worsened road surface and lack of money to repair it.

[TZ350]

.
Very interesting memories, thanks.

[katinas]

.
Very interesting memories, thanks.

Just remember other man from Great Britain Michael Sutton on Honda RS 250 , he was very fast at Tallin TT, but after 2 laps his engine seized, and this repeated 2 or 3 times at this event on the same cylinder. After one year, when I meet him again and asked about this, he smiled and said that later found very small invisible crack on that cylinder head.

[TZ350]

.
Such small things that conspire to defeat us...... :laugh: .... the 60's, 70's and 80's to me are the golden era of motorcycle racing.

An era when a guy and a couple of mates could cobble something together in the shed and go racing and mix it with the best. A bit like F4 and F5 Buckets is here in New Zealand now. I know Buckets is a pale shadow, but for me it brings back the memories and has the same sort of feel as that golden era.

[TZ350]

Kawasaki used it on KX 125 in 1986.

I am not sure of the year but here are some more pictures of the Kawasaki KX125 auxiliary exhaust ports.

337479 337480

[TZ350]

.
Shean Roberts and Hartog

<iframe width="560" height="315" src="https://www.youtube.com/embed/a1tGIgox3kM" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

[TZ350]

.
Munro. Someone I had the good fortune to spend an afternoon chatting with at his shed in 1970.

Here are some clips that someone put together about him.

<iframe width="560" height="315" src="https://www.youtube.com/embed/m_L1e2K71uw" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen=""></iframe>

<iframe width="560" height="315" src="https://www.youtube.com/embed/m-7juUCcSoU" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen=""></iframe>

<iframe width="560" height="315" src="https://www.youtube.com/embed/1lf3CaFj6K8" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen=""></iframe>

<iframe width="560" height="315" src="https://www.youtube.com/embed/5U1o-6OZ6Hs" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen=""></iframe>

[katinas]

Hartog riding style very different. Thanks Rob.

Maybe it would be interesting, found T. Harada TZ-M 1993 championship engine chart: head volumes 8,2cc from first to last 14 round, but fuel from 5 to 11 round ELF 130 ( all fast tracks). ELF 124 from 1 to 3 round and last part from 12 to 14

Add Yamaha OWH1 rotary valve engine pic, angle 60 and looks like firing is at the same time in both cylinders.

[guyhockley]

Yes, good idea, I will try that.

Have scoped things before but the rapid changes in Frequency (read RPM) makes it hard to adjust the time base so I can see the trace properly.

It is very hard to hold the RPM steady and synch the scope. Maybe I need to work it the other way around by setting the time base for 200 Hz and then revving the bike around 12,000 RPM. That way the trace will steady up at the target point instead of continuously running to the left or right across the screen. Either way its hard work and the trace is only readable over a narrow RPM band. Synchronization becomes a continuous moving target and has me working like the proverbial one armed paper hanger.

Anyway your suggestion makes very good sense and I will try it. Maybe there are more suitable scopes ........ :scratch:
Maybe you should give up all this nonsense and go to the next stage of induction technology...

[TZ350]

.

.....:scratch:... well it is tempting because we do have some of those Tillotson pumper carbs.....:eek:

337491

Like this the old Suzuki GP125 made 28 rwhp. Just need to attach another two and we would be onto a winner. .... :laugh:

[chrisc]

Took 6th and 5th at Assen this weekend in the Freetech championship which I'm over the moon with considering the pace of the bikes around me. And met some more really awesome Dutch racers. A number of the 2 stroke nuts have commented on visiting the kiwibiker forums when they hear I'm from New Zealand. For both this thread, the chassis thread and the foundry thread which I think is so damn cool.


https://www.youtube.com/watch?v=p1Qhv442FjM&t=503s

[F5 Dave]

That looks fun Chris.

[chrisc]

It really, really was Dave. I drove up from Croatia where I missioned down to in the long June break between events and the whole drive back I thought maaaaan I'm going to get my ass kicked. You see how much of that track is full throttle? And there are some faaaaaast 50s in that field. The challenge was fun and blowing my low expectations to pieces made it even more fun. Tonight we pulled an old Honda MB 50 out from under a shelter style shed which had been shitting for around 5 years. It has the paris dakar style body work to it and my team mate Roland rallied it around a grass track circuit back in the day. Started 3rd push! Thought about you and Malcolm the whole time. The only nuts still willing to fettle one of those slugs.

[husaberg]

It really, really was Dave. I drove up from Croatia where I missioned down to in the long June break between events and the whole drive back I thought maaaaan I'm going to get my ass kicked. You see how much of that track is full throttle? And there are some faaaaaast 50s in that field. The challenge was fun and blowing my low expectations to pieces made it even more fun. Tonight we pulled an old Honda MB 50 out from under a shelter style shed which had been shitting for around 5 years. It has the paris dakar style body work to it and my team mate Roland rallied it around a grass track circuit back in the day. Started 3rd push! Thought about you and Malcolm the whole time. The only nuts still willing to fettle one of those slugs.MT50?
https://i.pinimg.com/originals/b7/85/3b/b7853b219d959798e0efb219de69da30.jpg (https://www.google.co.nz/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjU-82Vh5PcAhVGlZQKHWxiAHwQjRx6BAgBEAU&url=https%3A%2F%2Fwww.pinterest.com%2Fpin%2F576108 977318851645%2F&psig=AOvVaw28C9KVTWiYLtjydpf772xa&ust=1531261329945392)

[chrisc]

337499337500

Unsure what the original pipe looked like as this one has been raced. I think it might have been a Holland only fairing model. But yeah probably MT50 not MB50. Same turd of a thing which only a wellingtonian would polish :Pokey:

[Muhr]

337499337500

Unsure what the original pipe looked like as this one has been raced. I think it might have been a Holland only fairing model. But yeah probably MT50 not MB50. Same turd of a thing which only a wellingtonian would polish :Pokey:

MB5 was quite popular when I grew up here in Sweden

http://japan.webike.net/moto_news/honda-mb50/

[F5 Dave]

Ha. I had a few MB50s. Went real well.

[SwePatrick]

337501

This new 50cc cylinder from Bidalot has reached 20hp according to this videoblog:

https://www.youtube.com/watch?v=LIk71wFp1nc&feature=youtu.be

[TZ350]

Took 6th and 5th at Assen this weekend in the Freetech championship which I'm over the moon with considering the pace of the bikes around me. And met some more really awesome Dutch racers. A number of the 2 stroke nuts have commented on visiting the kiwibiker forums when they hear I'm from New Zealand. For both this thread, the chassis thread and the foundry thread which I think is so damn cool.
https://www.youtube.com/watch?v=p1Qhv442FjM&t=503s

Hi Chris, great to watch your adventures in Europe.

Awsom video, thanks, and it is interesting to hear that people are reading some of the Bucket threads and enjoying them.

[husaberg]

Took 6th and 5th at Assen this weekend in the Freetech championship which I'm over the moon with considering the pace of the bikes around me. And met some more really awesome Dutch racers. A number of the 2 stroke nuts have commented on visiting the kiwibiker forums when they hear I'm from New Zealand. For both this thread, the chassis thread and the foundry thread which I think is so damn cool.


Hydraulic clutch as well? tre chic......


337499337500

Unsure what the original pipe looked like as this one has been raced. I think it might have been a Holland only fairing model. But yeah probably MT50 not MB50. Same turd of a thing which only a wellingtonian would polish :Pokey:
that pic is def a MB5
well at least, wheels, forks. and shocks
but the bodywork is all its own.

[Grumph]

Hartog riding style very different. Thanks Rob.



Hartog's riding style was indeed very different. Mike Sinclair in his book mentions that they could use very hard brake pads on Will's bike as, coming from an agricultural background, he had exceptional hand strength. To the point where he bent brake levers. They put a wide 16in front on his RG to get the most out of his braking ability.
Apparently when Sheene tried Wil's bike he couldn't get on with the high lever pressures needed.

[chrisc]

337501

This new 50cc cylinder from Bidalot has reached 20hp according to this videoblog:

https://www.youtube.com/watch?v=LIk71wFp1nc&feature=youtu.be

One of the Freetech racers is a test and development rider for Bidalot. Given what I’ve seen on track and spoken with him, I’d believe that. Keep in mind it requires all the other parts balanced properly to make it happen too.

[sispeed]

I also raced there in GP250 S1 with my modified Yamaha RD. Was very impressed by laptimes of the freetech class.
Thought to my self why are they so fast and I am so slow :eek5: My best laptime was 2:16,1

Regards Siggi

[katinas]

Hartog's riding style was indeed very different. Mike Sinclair in his book mentions that they could use very hard brake pads on Will's bike as, coming from an agricultural background, he had exceptional hand strength. To the point where he bent brake levers. They put a wide 16in front on his RG to get the most out of his braking ability.
Apparently when Sheene tried Wil's bike he couldn't get on with the high lever pressures needed.

Thanks, very interesting story.

I am very surprised when found this photo, that shows how Honda was keen about carbon comstar wheels, even after some Spencer's era problems. One of many changes that E. Lawson tried in 1989 was comstar "2nd version" front carbon wheel and AP brake discs. Carbon 3.75x16 =2.5kg, magnesium=2.6kg, but 17in version carbon= 2.83kg magnesium=2.81kg.

[wax]

I was looking at a 250 for a project im looking at doing
I find it interesting that the 125 is a square engine ( 54 x 54) but the new 250 mx bikes are longer stroke.
What gives is this to make more torque, is this a mx thing. On a circuit style engine would you still want a square engine ??

[husaberg]

Thanks, very interesting story.

I am very surprised when found this photo, that shows how Honda was keen about carbon comstar wheels, even after some Spencer's era problems. One of many changes that E. Lawson tried in 1989 was comstar "2nd version" front carbon wheel and AP brake discs. Carbon 3.75x16 =2.5kg, magnesium=2.6kg, but 17in version carbon= 2.83kg magnesium=2.81kg.

Even further back back Spencer on the threes ran a carbon wheel as did the NR500 before that only they had one explode pitching him off which is never a good look. the NR also had small wide wheels and slipper clutches and all sorts of common place stuff now.
Even with Erv fettling and chopping and changing the frame Lawson rode the 89 bike with the steering damper wound onto full.

[wobbly]

Wax, the 72 stroke that every 250MX uses is a best compromise between rpm capability and power band width.
Going shorter allows higher revs , and also higher power ,but comes with a corresponding reduction in usable band width.
The 250 MX bikes dont need any more outright power , except for the very , very few super expert riders , and that is easy enough to achieve.
The Honda 500V twin was close to 68 square as that is the best compromise for outright power capability and extended overev rpm.
The factory version was reported as 140Hp at the sprocket, and reved to 10500 all day, but exploded very quickly when taken to 11,000.
Its relatively heavy , high inertia flywheels , created havoc with speedshifting and the factory specifically highlighted in the manual not to fit one as
the gearbox would self destruct real fast due to the ignition cut cut not slowing the crank enough.

[wax]

Wax, the 72 stroke that every 250MX uses is a best compromise between rpm capability and power band width.
Going shorter allows higher revs , and also higher power ,but comes with a corresponding reduction in usable band width.
The 250 MX bikes dont need any more outright power , except for the very , very few super expert riders , and that is easy enough to achieve.
The Honda 500V twin was close to 68 square as that is the best compromise for outright power capability and extended overev rpm.
The factory version was reported as 140Hp at the sprocket, and reved to 10500 all day, but exploded very quickly when taken to 11,000.
Its relatively heavy , high inertia flywheels , created havoc with speedshifting and the factory specifically highlighted in the manual not to fit one as
the gearbox would self destruct real fast due to the ignition cut cut not slowing the crank enough.
Thanks Wobbly so it would stand to reason then that an engine converted to run in a kart would be better off as a square bore as you can deal with the peaky power more ??

[wobbly]

Dealing with a 250 in a kart is not easy in sprint racing due to the huge torque off corners.
The fastest here is a modified 125KZ engine on one side and a 100cc reed direct drive on the other.
In road racing the big issue is that all of the modern MX engines are long stroke so favor torque over high rpm power, but when tuned
the issue then becomes the huge gap to 5th gear ( no 6 speeds any more ).
Thus they are tuned to rev past 11,000 so they drop back near the torque peak, and will still accelerate.
Older YZ250 had 68 square , but old fashioned port layout that would take a huge effort to update.

[katinas]

Even further back back Spencer on the threes ran a carbon wheel as did the NR500 before that only they had one explode pitching him off which is never a good look. the NR also had small wide wheels and slipper clutches and all sorts of common place stuff now.
Even with Erv fettling and chopping and changing the frame Lawson rode the 89 bike with the steering damper wound onto full.

They have very radical steering geometry in 89: most marginal version, rake- 20.58, trail-74.6mm, wheelbase-1358mm, but engine changed for torque, maybe first time not for peak: 165 hp -12000rpm. (163 hp 12500rpm 88') Looks like HRC experimenting very hard between 88-90, twin-crank 500, fuel injected NSR 250.
For chassis Honda chose strong 7000 Zn series good welding properties (very small or zero Cu) 7003 T4 alloy. Welding zone strength, after temper, remains 90 percents of main structure.
I'm not sure, but looks like 7003 alloy was used for NS 250/400, as I cut rear frame (prepare bike for racing) and put some pieces in lathe, after some cuttings welding zone looks same like main material, feels really like 7000 and stronger than RGV 250. Maybe for RGV, Suzuki used 6000 series alloy, but I'm not sure.

[mclarengp]

Hey guys
Great thread I’m only at the start but making my way through and hopefully have my gp singing with some of the great ideas!!! I’ll be racing against the old mc22 which I previously raced and I’ll probably get lapped hahahahaha I’ve link a few imagines of bike so far , will also be getting it logged booked to race classic and keeping original forks and will have to get tricky with internals

[TZ350]

.
Great, I love those GP's .... :niceone:

The team GP's would flap all about the place when pressed hard so we beefed up the frames with all sorts of bracing but found that the more we "improved" the frame the handling got worse. never figured that out. The GT185 forks with gold valves and bracing were an improvement and so were a good set of inexpensive medium weight rear shocks.

We ran a RG250 chamber at first and that was quite good and a great place to start then later ran a Honda NF4 RS125 chamber which worked very well and was quite easy to fit.

[Matt@TYGA]

The Honda 500V twin was close to 68 square as that is the best compromise for outright power capability and extended overev rpm.
The factory version was reported as 140Hp at the sprocket, and reved to 10500 all day, but exploded very quickly when taken to 11,000.
Its relatively heavy , high inertia flywheels , created havoc with speedshifting and the factory specifically highlighted in the manual not to fit one as
the gearbox would self destruct real fast due to the ignition cut cut not slowing the crank enough.

Had the pleasure of riding two NSR500V's at Donington. The first a 2001 spec with kit parts. Made just shy of 140 at the wheel I believe and was an absolute missile. Surprisingly (thankfully?) not as difficult to ride as I thought it would be. Revved to around 11,500 and occasionally 12k and seemed happy to do it. Twas frightfully rapid. The next one was a '98 version. Around 130 ish ponies, wrapped in a TSR chassis (TSR AC50). Wasn't quite as fast and was hooking gears at around 10,500rpm, but it was beautiful in the handling department. Same day was also granted a couple of laps on an RS500 triple. That was a shock to the system! Not sure exact year/model, but guess late 80's. Handling?....interesting....brakes?....what brakes?....engine?....was jetted way to rich but cleared up around 8k and was clicking cogs at 10k.

Trying to keep two wheel on the ground on a 500 is no easy task :eek:

https://www.youtube.com/watch?v=ooqeQ2Jmgt0&t=64s

[SwePatrick]

My weldproject as arrived from nicasilplating.
This is my downstroked kx250 engine, from 72mm down to 61mm
My other cylinder has dynoed 68hp at 13100rpm on the rear wheel, i´m hoping for stepping above 70hp with this one.
If not? i will blend in some nitro in the fuel.


337546

[TZ350]

.
Nitro ....... :2thumbsup ... love it.

[peewee]

looks like nice work Patrick. I was testing mine alittle more today with the 30%. I made the needle 1 turn richer from last time but it still has alittle zing when clearing the crankcase. maybe it needs 1 more turn rich but really its not a big problem I guess.



https://youtu.be/JCl3n7Bxlc4

[F5 Dave]

My weldproject as arrived from nicasilplating.
This is my downstroked kx250 engine, from 72mm down to 61mm
My other cylinder has dynoed 68hp at 13100rpm on the rear wheel, i´m hoping for stepping above 70hp with this one.
If not? i will blend in some nitro in the fuel.


337546

I was assuming you'd be blending more vodka into your beverage.

[TZ350]

Need a good quality laptop based scope not little old small screen electronics scope.

Following Diesel62's suggestion I went looking for a PC scope. I was not able to afford the real deal but was able to find a free ware PC based scope and signal generator.

337555

This is good enough for what I need. A signal generator to simulate an ignition trigger signal and crankcase pressure wave from 1,000 to 13,000 RPM, 16 to 220 Hz. I can use the signal generator to simulate my engine while developing the Arduino program.

The EngMod 2T simulations show crankcase pressure traces from 5-100% throttle and interestingly all the peaks are at the same crank angle.

Because the MAP sensor is slow compared to the short time available Flettner suggested, instead of making a continuous pressure measurement to find the high and low point like I have been trying to do. Just make one or two at the critical points.

Flettners suggestion looks like a great idea.

337554

As I am only looking for the relative difference between the High and Low pressure points then I could just chose an arbitrary low point and compare the relative magnitudes of the peaks from there. That would be a reliable indication of changes in air flow and only one measurement per cycle would be required, much easier.

The Ecotrons 2T EFI software has the VE map (RPM vis MAP) disabled and only allows for an Alpha-N map (RPM vis TPS) and this is totally useless for variable changes in airflow at the same RPM/TPS points on the Alpha-N map.

So I also need a 4T style VE map (RPM vis MAP) as the MAP indicates variations in airflow. But I have so far been unable to persuade Ecotrons to enable the VE map in my tuning software, "Because they don't recommend it". They might be great at writing software code but I am not sure they are 2T experts.

I was talking with Marsheng today and he suggested that if I can't use the MAP input on a VE table to indicate the reduced airflow then I could use the TPS input on the Alpa-N table. The idea is to indicate an artificially low TPS for the actual throttle position when I wanted to tell the EFI CPU that the air flow was momentarily reduced.

Makes sense, get the Arduino to read the TPS signal and the crankcase pressure and then simulate a reduced TPS value for the EFI CPU when the peak crankcase pressure is reduced because of reduced airflow due to reduced wave energy in the expansion chamber.

This way we can have a full normal TPS signal when the motor is on song and the pipe is strongly sucking air through the motor and the TPS signal can be artificially reduced to indicate reduced airflow and fuel requirement when the wave action in the pipe has collapsed and there is less air being drawn through motor.

Brilliant ideas, thanks Diesel62, Flettner and Marsheng.

[Flettner]

i think the latest Link has a built in oscilloscope in the softwear.

[speedpro]

Strangely enough this is more or less where I've gone with the Link system on my turbo 100(cough).
Off boost the fuel is determined in the main fuel table by TPS vs RPM. Without the turbo this would be sufficient to make the motor run fine. I have however enabled what Link call a 4d table which acts to modify the fuel requirement calculated by the main table. I've configured the 4D table to use MAP vs RPM. The lowest MAP value is 0BAR or atmospheric so below 0BAR it has no effect. Any increase in pressure(boost) causes the value in a cell to be used to modify the fuel. The cell and therefore the value is determined by boost at any particular RPM. The 4D table can be used to add or subtract fuel. I could add a 5D table as well if there was some other value I wanted to monitor and use to modify the amount of fuel. Any Link fuel table can have any variable designated on any axis. The main fuel table could be MAP or TPS or a few other variables.
There will of course still be variation in air flow below 0BAR dependent on whether the turbo is spooling up or not but just having it a bit rich seems to cover that transition period where the turbo is spooling up. If I found that just below 0BAR there was a fuel problem with the turbo spooling up I can simply change the first value on the Y-axis to something below 0BAR.
The "Help" function on the Link is very good with suggestions on how to configure the system depending on a number of variables such as cams, weak or erratic vacuum, turbo or supercharged, and others.
Shame I haven't had time to work on it over the last month or more.

[speedpro]

i think the latest Link has a built in oscilloscope in the softwear.
It doesn't on my Atom but later and greater systems it does. You can check for instance the trigger waveforms.

[Flettner]

As i said, the link is very versatile.

[JanBros]

I was able to find a free ware PC based scope and signal generator.


can we have a link ?

[husaberg]

Following Diesel62's suggestion I went looking for a PC scope. I was not able to afford the real deal but was able to find a free ware PC based scope and signal generator.

337555

This is good enough for what I need. A signal generator to simulate an ignition trigger signal and crankcase pressure wave from 1,000 to 13,000 RPM, 16 to 220 Hz. I can use the signal generator to simulate my engine while developing the Arduino program.

The EngMod 2T simulations show crankcase pressure traces from 5-100% throttle and interestingly all the peaks are at the same crank angle.

Because the MAP sensor is slow compared to the short time available Flettner suggested, instead of making a continuous pressure measurement to find the high and low point like I have been trying to do. Just make one or two at the critical points.

Flettners suggestion looks like a great idea.

337554

As I am only looking for the relative difference between the High and Low pressure points then I could just chose an arbitrary low point and compare the relative magnitudes of the peaks from there. That would be a reliable indication of changes in air flow and only one measurement per cycle would be required, much easier.

The Ecotrons 2T EFI software has the VE map (RPM vis MAP) disabled and only allows for an Alpha-N map (RPM vis TPS) and this is totally useless for variable changes in airflow at the same RPM/TPS points on the Alpha-N map.

So I also need a 4T style VE map (RPM vis MAP) as the MAP indicates variations in airflow. But I have so far been unable to persuade Ecotrons to enable the VE map in my tuning software, "Because they don't recommend it". They might be great at writing software code but I am not sure they are 2T experts.

I was talking with Marsheng today and he suggested that if I can't use the MAP input on a VE table to indicate the reduced airflow then I could use the TPS input on the Alpa-N table. The idea is to indicate an artificially low TPS for the actual throttle position when I wanted to tell the EFI CPU that the air flow was momentarily reduced.

Makes sense, get the Arduino to read the TPS signal and the crankcase pressure and then simulate a reduced TPS value for the EFI CPU when the peak crankcase pressure is reduced because of reduced airflow due to reduced wave energy in the expansion chamber.

This way we can have a full normal TPS signal when the motor is on song and the pipe is strongly sucking air through the motor and the TPS signal can be artificially reduced to indicate reduced airflow and fuel requirement when the wave action in the pipe has collapsed and there is less air being drawn through motor.

Brilliant ideas, thanks Diesel62, Flettner and Marsheng.
It occured to me the other day you could just use a dirty old tech vane type airflow meter.
https://www.youtube.com/watch?v=Xkyfjo7spFc

[TZ350]

can we have a link ?

https://www.zeitnitz.eu/scope_en

337556

[TZ350]

It occured to me the other day you could just use a dirty old tech vane type airflow meter.
https://www.youtube.com/watch?v=Xkyfjo7spFc

A vain looks great for steady uniflow air. And could be just the ticket if I was running a big plenum, which was my original reason for getting into 2T EFI.... :scratch:

I have not tried a vane because, apart from the unwanted extra length to the inlet tract I suspect a performance 2T's changes in air flow will be violently flapping the vane up and down and that will confuse the CPU right up to the point where the 2T finally rips the vane right off and swallows it.

Still that is just my suspicions and a vane may be worth looking at. I have seen what look like small scooter sized ones on a Japanese auction sight.

But if someone wants to temporally tape a car one to the bellmouth of their carb and scope the signal I would love to see how consistent the trace is.

[TZ350]

As i said, the link is very versatile.

The Arduino thing is still a useful line of inquiry because whichever unit I use I still need to solve the problem of identifying changes in air flow.

337557

Your idea of only reading the MAP sensor at a set crank angle looks very promising.

Time is running out for Ecotrons, a Link is looming large on the horizon.

[TZ350]

337558

Blue line = RPM. Brown line = LamWO2. Pink line = Injection pulse width. TPS = 100%

Cursers are both at the same TPS, RPM, Alpha-N load, and Injection PW.

On the left the engine is coasting down with the throttle held open and steady, LamWO2 a little lean, engine picks up at about 7,000rpm when air flow matches Alpha-N fueling and accelerates back to full power and rpm.

A little lean in reality can be an indication it is too rich to fire.

Left and Right sides both pass through the same Alpha-N map cells. Nath88 clued me into this. The air flow is different, there is much more air flow on the right than the left. After shutting the throttle as would when peeling into a corner the exhaust wave has collapsed it does not re-establish until the motor has been firing properly again for a bit. The motor coasts down until the airflow matches the fueling at some point on the Alpha-N map (TPS/RPM) and the motor starts firing again and after a bit it re establishes the wave action in the pipe.

337559

For the same RPM and TP throttle position you can have very different air flows through the motor. It all depends on the strength of the wave action in the pipe. The wave action collapses when you throttle off for a corner and takes some time to re establish itself after throttling on again. This is where those pesky 4T's get the jump on you at the track.

Alpha-N is a bit ridged as it only works with RPM and TPS so it cant flexible adjust the fueling because it cant see changes in airflow.

VE volumetric efficiency works with RPM and MAP or MAF and so it can flexibly adjust fueling because it can see changes in air flow.

But the problem is that all the EFI systems I have seen are aimed at 4T's and all of them don't have an easy way to identify changes in air flow through a high performance two stroke motor. Ie a 2T motor that is heavily dependent on its pipe for its performance.

A work around is required to marry a 4T EFI system to the needs of a 2T. Traditional 4T ways of measuring air flow are not appropriate for 2T's so some other way of doing it is required.

Some sort of work around is required.

[husaberg]

A vain looks great for steady uniflow air. And could be just the ticket if I was running a big plenum, which was my original reason for getting into 2T EFI.... :scratch:

I have not tried a vane because, apart from the unwanted extra length to the inlet tract I suspect a performance 2T's changes in air flow will be violently flapping the vane up and down and that will confuse the CPU right up to the point where the 2T finally rips the vane right off and swallows it.

Still that is just my suspicions and a vane may be worth looking at. I have seen what look like small scooter sized ones on a Japanese auction sight.

But if someone wants to temporally tape a car one to the bellmouth of their carb and scope the signal I would love to see how consistent the trace is.
Bulky yip,but if you ran a closed intake they could be part on the inlet for this, not sure how they will go in a 2t single but the RX7's had them?

[speedpro]

Get with technology guys. Flaps haven't been used for Mass Air flow sensors for ages. The last time I checked, a heated wire was used, no moving parts. Just a controller to maintain the current through the wire at a constant value. The amount of voltage to maintain the current is proportional to the air flow cooling the wire. It could be done the other way - applying a constant voltage and measuring the current. You could add a bit of mass to smooth out the variations.
Another way, but probably a bit less responsive than required, would be to use a bimetallic junction to heat or cool a small mass and a temp sensor to measure the temperature. At high airflow the mass would have heat removed requiring current to be applied to the bi-metallic junction to heat it. Again current would be proportional to mass air flow. Depending on the bi-metallic junction you could operate it in the crossover region where current reversed and it went from cooling to heating though probably simpler to have it in the heating only direction.

[husaberg]

Get with technology guys. Flaps haven't been used for Mass Air flow sensors for ages. The last time I checked, a heated wire was used, no moving parts. Just a controller to maintain the current through the wire at a constant value. The amount of voltage to maintain the current is proportional to the air flow cooling the wire. It could be done the other way - applying a constant voltage and measuring the current. You could add a bit of mass to smooth out the variations.
Another way, but probably a bit less responsive than required, would be to use a bimetallic junction to heat or cool a small mass and a temp sensor to measure the temperature. At high airflow the mass would have heat removed requiring current to be applied to the bi-metallic junction to heat it. Again current would be proportional to mass air flow. Depending on the bi-metallic junction you could operate it in the crossover region where current reversed and it went from cooling to heating though probably simpler to have it in the heating only direction.
Problem with the heated wire is it doesn't like lead and it is a bit more restrictive than it seems by the name.
http://www.onlinecarparts.co.za/487-1306-thickbox/nissan-almera-primera-mass-air-flow-meter-maf-5-pin-oe-22680-5u400.jpg
But yes most are this set up now if not MAP some are both like the EVO's

[diesel62]

337558

Blue line = RPM. Brown line = LamWO2. Pink line = Injection pulse width. TPS = 100%

Cursers are both at the same TPS, RPM, Alpha-N load, and Injection PW.

On the left the engine is coasting down with the throttle held open and steady, LamWO2 a little lean, engine picks up at about 7,000rpm when air flow matches Alpha-N fueling and accelerates back to full power and rpm.

A little lean in reality can be an indication it is too rich to fire.

Left and Right sides both pass through the same Alpha-N map cells. Nath88 clued me into this. The air flow is different, there is much more air flow on the right than the left. After shutting the throttle as would when peeling into a corner the exhaust wave has collapsed it does not re-establish until the motor has been firing properly again for a bit. The motor coasts down until the airflow matches the fueling at some point on the Alpha-N map (TPS/RPM) and the motor starts firing again and after a bit it re establishes the wave action in the pipe.

337559

For the same RPM and TP throttle position you can have very different air flows through the motor. It all depends on the strength of the wave action in the pipe. The wave action collapses when you throttle off for a corner and takes some time to re establish itself after throttling on again. This is where those pesky 4T's get the jump on you at the track.

Alpha-N is a bit ridged as it only works with RPM and TPS so it cant flexible adjust the fueling because it cant see changes in airflow.

VE volumetric efficiency works with RPM and MAP or MAF and so it can flexibly adjust fueling because it can see changes in air flow.

But the problem is that all the EFI systems I have seen are aimed at 4T's and all of them don't have an easy way to identify changes in air flow through a high performance two stroke motor. Ie a 2T motor that is heavily dependent on its pipe for its performance.

A work around is required to marry a 4T EFI system to the needs of a 2T. Traditional 4T ways of measuring air flow are not appropriate for 2T's so some other way of doing it is required.

Some sort of work around is required.Good to see scope working for you
Could you just run Egt and tps. Wouldn't that tell you all you need to know.
It doesn't really matter what is happening in the crankcase
100% tps egt must CONTINUE to climb to 620 C ish.
If you had a lookup table tps /rpm/egt.
Or acceleration sensor to tell if on or off throttle

Sent from my SM-P555 using Tapatalk

[husaberg]

A view of a YZR500 i have never seen before
337566

[Frits Overmars]

The last time I checked, a heated wire was used, no moving parts. Just a controller to maintain the current through the wire at a constant value. The amount of voltage to maintain the current is proportional to the air flow cooling the wire.Problem: the wire can't tell inflowing air from outflowing air. The same mass of air might even pass the wire four times during the inlet phase and still end up outside of the crankcase.
Shielding one side of the wire does help a bit, but not enough. A second wire downstream of the first one, and some clever software, might be a solution, but at the cost of increased inlet tract length.

[TZ350]

.
A spit of fuel on the wire confuses things too.

[speedpro]

I thought we were considering port injected 2 strokes. But yes, I see the problem. Surely at the entrance to an airbox the flow would essentially be one way.
The multidirectional airflow would be a problem with any measuring device. The flapper valve would become a multipurpose reed valve. That sort of sounds like disc valve defeat.

[TZ350]

I thought we were considering port injected 2 strokes.

True, but vertically down the B port. Not as much but sadly some fuel still finds its way out of the inlet. An air flow meter on a large airbox is a good idea, and maybe the way the RONAX and SUTER do it, who knows? but it is not my plan, I think there is a better less cumbersome and more direct way.

[Frits Overmars]

An air flow meter on a large airbox is a good idea... but it is not my plan, I think there is a better less cumbersome and more direct way.Yes, I think you're on the right track with your approach, TeeZee.

[SwePatrick]

looks like nice work Patrick. I was testing mine alittle more today with the 30%. I made the needle 1 turn richer from last time but it still has alittle zing when clearing the crankcase. maybe it needs 1 more turn rich but really its not a big problem I guess.



https://youtu.be/JCl3n7Bxlc4

Nice.
IT seems to shovel a lot of dirt =)

[SwePatrick]

First startup with the new cylinder, the rattling is the clutch, no springs, dragrace setup.
Overall it went nice.
Kickstarter rubbed against the frame and a blindnut in the floatbowl got loose therefor it died on me, and the fuel on the floor.
The blindnut is blocking a hole in the bowl as i haven´t got the powerjet mounted yet, it is on one of my other carbs.


https://youtu.be/jqN4IyCDQpU[/QUOTE]

[Carel H]

Some sort of work around is required.

Why not see it as a standard event?

You close the throttle and the average (blip filter) TPS position drops, the exhaust cools. If the average position drops below a certain threshold a timer is started. The timer stops at the time the pipe is considered "cold".

If the average TPS position then exceeds a threshold you can use a formula such as (for simplicity assuming cooling time equals heating time):

TPS input - (Cooled time/Cold time * Injection correction) = TPS output.
Cooled time = Cooled time - 1 till cooled time = 0

It'sa KISS bandaid. No sensor problems.

[SwePatrick]

I have mentioned it before, a L-jetronic air meter should probably work without mods, just alter the springtension.

http://www.gomog.com/allmorgan/afmdiag.jpg

[Flettner]

pretty sure this is a fuel injected twostroke, single cylinder too. Hot bulb type, ie squirt the fuel at the hot bulb in the combustion chamber. Thought about that TZ? :msn-wink:
https://youtu.be/psSkJ5K709o

[TZ350]

Yes, I think you're on the right track with your approach, TeeZee.

Well actually it was Flettners original idea to measure the crankcase pressure at a set point. He suggested a sample and hold approach and tried it with a small rotating valve timed to the peak crankcase pressure. It showed promise on his 360. I am just trying to refine it a bit by using a small PLC.

[ken seeber]

Tzee, I reckon that any device like a vane style air flow meter, or even a hot wire, if it has an adequate damping volume downstream to ensure a nett one way flow to the engine, will be so slow to respond that it’s out of the question. You need a indicative signal every rev.

As you suggest, sampling crankcase pressure at some suitable fixed point might be the go, even with Fletto’s opening valve. Either way, it’ll need a presure sensor with good response.

Brett suggested some time ago an IR sensor that was set into the top of a transfer port, aimed into the cylinder. With this, essentially sampling at a fixed crank angle, one could infer the temp, hence whether combustion took place or not, then inject the right amount of fuel possible for the same cycle (by altering the injector closing angle point), or certainly the next cycle.

[TZ350]

As you suggest, sampling crankcase pressure at some suitable fixed point might be the go, even with Fletto’s opening valve. Either way, it’ll need a pressure sensor with good response.

For good response I am going to try a MAP sensor (which we know are relatively slow) to get the ambient outside air pressure for a base line and use a Piezo for the positive crankcase pressure pulse. Piezo's are fast in comparison. All I am looking for is relative changes in maximum crank case pressure.

The evolution of KTM's EFI cylinders. In conversation maybe about 2012 Flettner advised them go for vertically down the B ports like he has on the BigHorn. They told him they would do something more sophisticated.

337583

Cylinder on the left is their sophisticated effort, direct injection, middle is direct port injection, cylinder on the right is vertically down the B ports just like Flettner suggested and it must be what works best as they are currently running them on their ""revolutionary"" fuel injected bikes.

Flettner is certainly worth listening too.

[jonny quest]

A view of a YZR500 i have never seen before
337566

Looks old. Rotating drum powervalve?

[jonny quest]

For good response I am going to try a MAP sensor which we know are relativly slow to get the ambient outside air pressure for a base line and use a Piezo for the positive crankcase pressure pulse. Piezo's are fast in comparison. All I am looking for is relative changes in maximum crank case pressure.

The evolution of KTM's EFI cylinders. In conversation maybe about 2012 Flettner advised them go for vertically down the B ports like he has on the BigHorn. They told him they would do something more sophisticated.

337583

Cylinder on the left is their sophisticated effort, direct injection, middle is direct port injection, cylinder on the right is vertically down the B ports just like Flettner suggested and it must be what works best as they are currently running them on their ""revolutionary"" fuel injected bikes.

Flettner is certainly worth listening too.

The cyl on left is Orbital design. Frits can chime in... uses direct air injection along with direct fuel injection.

[SwePatrick]

Some new testing today.
I´m testing my sliderclutch.
This is the first time ever i have been in contact with this, i designed it myself, it works, but it seems from video it is somewhat light weights, further testing will need to be done.
Still i´m happy it works, a small step for human kind, but a big step for me ;)


https://youtu.be/NH3S86STmRA

[peewee]

Nice.
IT seems to shovel a lot of dirt =)

yes it can shovel plenty of dirt :2thumbsup. It seems the nitro gives extra torq for some reason but im not sure why, maybe because the quantity of fuel put in the cylinder can be increase alot, just a guess. even with just 30% you can double the fuel through the powerjets. with methanol at 80F I could use just one powerjet full open. now at 30% I can use atleast two powerjet full open and the third jet half open. what I plan to do next testing is continue to open the third jet and fourth jet to see if the engine gets to a point where it drowns in the fuel and can barely run. then atleast I can know the limits of the AFR

[SwePatrick]

It´s easy,, Nitro brings its own oxygen.
More oxygen = capable of burning more fuel.

[Frits Overmars]

The cyl on left is Orbital design. Frits can chime in... Thanks for the flowers Jonny, but I'll leave this one to Ken Seeber; he used to work at Orbital.


It seems the nitro gives extra torq for some reason...
337590

[Flettner]

my Kawasaki has a what i call a read and hold device for crank case sampling.
crude and mechanical (my style) a small pneumatic valve, 12V . Its switched on for a short time every cycle to read the crank case pressure at a given crank point every cycle, 'read and hold'.
I could not belive that the valve could cycle at engine frequency but apparently it can. TZ is much cleverer, hes making an electronic version.

[TZ350]

It´s easy,, Nitro brings its own oxygen. More oxygen = capable of burning more fuel.

True Nitro brings its own oxygen and even more fuel. So if you inject Nitro into an already correct air/fuel mixture then the mixture with added Nitro goes slightly rich. Nitro has a lot of oxygen and even more fuel, so richer not leaner, very handy.

[peewee]

True Nitro brings its own oxygen and even more fuel. So if you inject Nitro into an already correct air/fuel mixture then the mixture with added Nitro goes slightly rich. A lot more oxygen and fuel but richer not leaner, very handy.

i wish there was more info about nitro in 2t engines. oil content in rc fuel ranges from 10%-22%. i havent figured out why. maybe parts last longer with more oil. ive been mixing 30% nitro, 16% oil, 54% methanol. if i lower the oil to say 12% and raise the methanol to 58% i wonder if i would gain power. maybe the engine would wear out faster. i dont know

[TZ350]

i wish there was more info about nitro in 2t engines. oil content in rc fuel ranges from 10%-22%. i havent figured out why. maybe parts last longer with more oil. ive been mixing 30% nitro, 16% oil, 54% methanol. if i lower the oil to say 12% and raise the methanol to 58% i wonder if i would gain power. maybe the engine would wear out faster. i dont know

When I was running a TZ back in the day. Castrol R or Shell M was 12:1 running in and 16:1 or 18:1 racing. We wound up using 20:1 because it was an easy mix ratio. 1l oil pack into 20l fuel tin, hard for the pit bunny to cock that up but they often gave it an honest try. Back in the day the rule of thumb was more oil made more power.

[TZ350]

you can double the fuel through the powerjets. with methanol at 80F I could use just one powerjet full open.what I plan to do next testing is continue to open the third jet and fourth jet to see if the engine gets to a point where it drowns in the fuel and can barely run. then at least I can know the limits of the AFR

My experience with methanol and 2T's (Suzuki TR250R and Yamaha RD's) is that you can run them so rich that raw wet fuel runs out of the exhaust pipes wetting any riders that are close behind.

In fact you can take a correctly jetted methanol motor with the correct rich AF, increase the methanol and the motor runs cold, and then does not evaporate the fuel and the AF goes lean, more fuel makes it worse.

You have to strike a balance by blending the fuel to get the motor to run at a reasonable temperature. My favorite blend was 50/50 Methanol Acetone. But you could use other fuels. And even though we were pumping a lot more fuel through we still used 20:1 oil ratio.

[SwePatrick]

increase the methanol and the motor runs cold, and then does not evaporate the fuel and the AF goes lean, more fuel makes it worse.



Spot on!
But if one is able to get the engine hot enough to evaporate the fuel even thou you are running huge amounts of fuel, then it will be a good powerboost.
Here´s where nitro comes in, i dunno exactly where nitro 'takes' over.
But at smaller amount like 15-30% blend in methanol i call the nitro 'activator'.
You got all the good parts from methanol AND activates the heat so it can burn even more fuel, this with the added oxygen in nitro.

Another way to activate the 'heat' is to decrease the cooling in the head when running methanol, this lets you burn more methanol also.

337596

This is simple physics actually.
Boilingpoint of methanol is 64,7c
Boilingpoint of petrol is more funny, it depends on pressure, ca 30-190c

[TZ350]

.
I like it ....:niceone:

[husaberg]

Some new testing today.
I´m testing my sliderclutch.
This is the first time ever i have been in contact with this, i designed it myself, it works, but it seems from video it is somewhat light weights, further testing will need to be done.
Still i´m happy it works, a small step for human kind, but a big step for me ;)


https://youtu.be/NH3S86STmRA

Slider Like a Ktm50?

[SwePatrick]

Slider Like a Ktm50?

Almost, but with huge possibilites with adjustment.

337597

[husaberg]

Almost, but with huge possibilites with adjustment.

337597

looks kind of similar to the Tomar ones for the KTM50 just many more plates
http://www.tomarengineering.com/media/catalog/product/cache/14/image/435x375/9df78eab33525d08d6e5fb8d27136e95/5/6/560013_6.jpghttp://www.tomarengineering.com/media/catalog/product/cache/14/image/435x375/9df78eab33525d08d6e5fb8d27136e95/4/8/482055.jpg

[SwePatrick]

Yes, very similar =)

here´s a video of what happens when adjusting.

https://www.youtube.com/watch?v=STrAI5Xz0vw

[ken seeber]

TZee you got me interested, particularly when I should be doing other stuff.

Ultimately, under most conditions, we possibly want an engine that has combustion every cycle, certainly eliminating the “ring…ding” nature of a carb’d 2 stroke under light load.

At Orbital, I remember at around the mid 90s when we first fitted the OCP system to a 50 cc Piaggio scooter. This used a 2.5 cc compressor that was driven by a spring loaded piston that was actuated via a roller running on an eccentric on the outside diameter of the engine crank, ingesting its air (and oil) from the crankcase. Once satisfactorily mapped, the thing combusted every cycle. To me it was almost annoying, especially at idle, in that it sounded so busy compared to a (misfiring) carb engine at the same speed.

Anyways it is clear, that a 2 stroke can be fuelled to provide reliable “cycle to cycle” combustion under all load & speed conditions, in this case with direct injection (no air flow measurement, just TPS).

Back to a carb engine, what happens when an engine isn’t going “ding”, when the engine is well off the exhaust providing any useful tuning effect, say at idle. Assuming a reed valve engine, one would think that the air/fuel charge per cycle would be very consistent. So, if we are pumping this repeatable air/fuel mass into the upper cylinder every cycle, why does it misfire?

Possible reasons are:
1. The fuel entry into the cylinder could be so stratified (due to low gas velocities) that the majority short circuits out the exhaust. This continues until the percentage of fuel increased until such time that as combustible mixture is present at the time of ignition. Then the “ding”.
2. That the exhaust gradually cools, altering the timing of a possible positive/negative pulse.
3. Ring leakage is such that the pressure in the cylinder, under non firing conditions, is less at EPO than EPC, back flowing some exhaust gas diluted charge in the cylinder.
4. Dunno
5. Dunno etc

Considering point 1. it could be argued that the scavenging gas flow from the injected B ports would take a shorter path out to the exhaust than say the C port, which one could imagine in the Schnurle scaving system would have the longest path. So, it’d be interesing to inject into this alone rather than the B ports.

As an aside, if we are dumping all this nice combustible mix into the exhaust for a number of cycles, why don’t we get a decent bang in the exhaust, similar to a “key bang” in a 4 stroke car, most usually blowing the muffler to bits. Dontchaeverrememberingdoingthisparticularlyinsomeo neelsescar???

I do recognise that this is a bit away from the sub 25% control problem, but there are some commonalities.

[husaberg]

TZee you got me interested, particularly when I should be doing other stuff.

Ultimately, under most conditions, we possibly want an engine that has combustion every cycle, certainly eliminating the “ring…ding” nature of a carb’d 2 stroke under light load.

At Orbital, I remember at around the mid 90s when we first fitted the OCP system to a 50 cc Piaggio scooter. This used a 2.5 cc compressor that was driven by a spring loaded piston that was actuated via a roller running on an eccentric on the outside diameter of the engine crank, ingesting its air (and oil) from the crankcase. Once satisfactorily mapped, the thing combusted every cycle. To me it was almost annoying, especially at idle, in that it sounded so busy compared to a (misfiring) carb engine at the same speed.

Anyways it is clear, that a 2 stroke can be fuelled to provide reliable “cycle to cycle” combustion under all load & speed conditions, in this case with direct injection (no air flow measurement, just TPS).

Back to a carb engine, what happens when an engine isn’t going “ding”, when the engine is well off the exhaust providing any useful tuning effect, say at idle. Assuming a reed valve engine, one would think that the air/fuel charge per cycle would be very consistent. So, if we are pumping this repeatable air/fuel mass into the upper cylinder every cycle, why does it misfire?

Possible reasons are:
1. The fuel entry into the cylinder could be so stratified (due to low gas velocities) that the majority short circuits out the exhaust. This continues until the percentage of fuel increased until such time that as combustible mixture is present at the time of ignition. Then the “ding”.
2. That the exhaust gradually cools, altering the timing of a possible positive/negative pulse.
3. Ring leakage is such that the pressure in the cylinder, under non firing conditions, is less at EPO than EPC, back flowing some exhaust gas diluted charge in the cylinder.
4. Dunno
5. Dunno etc

Considering point 1. it could be argued that the scavenging gas flow from the injected B ports would take a shorter path out to the exhaust than say the C port, which one could imagine in the Schnurle scaving system would have the longest path. So, it’d be interesing to inject into this alone rather than the B ports.

As an aside, if we are dumping all this nice combustible mix into the exhaust for a number of cycles, why don’t we get a decent bang in the exhaust, similar to a “key bang” in a 4 stroke car, most usually blowing the muffler to bits. Dontchaeverrememberingdoingthisparticularlyinsomeo neelsescar???

I do recognise that this is a bit away from the sub 25% control problem, but there are some commonalities.
Have you seen this one Ken
its a tiny high ultra pressure pump.
https://www.popularmechanics.com/cars/hybrid-electric/a9263/the-20-device-to-replace-dirty-carburetors-15682450/
https://news.engin.umich.edu/2012/09/cleaner-motorcycle-engines-student-startup-inspired-by-growing-emissions-in-asia/
have a look at the fuel spray

https://www.youtube.com/watch?v=UB34NMoBRGA
kind of reminds me of a hilborne system only electric
http://www.freepatentsonline.com/20140117121.pdf

[SwePatrick]

I mentioned earlier to raise heat in the head with methanol.
This is my coolant scheme:

337600

Original waterpump(increased flow) is drawing cool water from radiator as it should.
It is pumping the cool water into the cylinder above the exhaustduct in a 20mm line.
Then purple line is 12mm and is going directly to the radiator.
The red 12mm line from the head is controlled by a 90c thermostat, and then flowing into radiator.
The cylinder has restricted flow in the deck so there are a smaller flow than std going through the head.

If it is working?
Dunno yet, i´m testing clutch back and forth to get some baseline of what´s working.
Later this week i´m guessing i´ll put it on the dyno.

[lohring]

i wish there was more info about nitro in 2t engines. oil content in rc fuel ranges from 10%-22%. i havent figured out why. maybe parts last longer with more oil. ive been mixing 30% nitro, 16% oil, 54% methanol. if i lower the oil to say 12% and raise the methanol to 58% i wonder if i would gain power. maybe the engine would wear out faster. i dont know

I've been racing model boats a long time. In 3.5 to 15cc glow ignition engines we run 50 to 60% nitro with around 20% synthetic oil. Castor oil doesn't mix with high nitro, but castor/synthetic blends are also used. The oil is more for sealing the ringless pistons than for lubrication. Record setting engines often run up to 80% nitro. Other exotic chemicals like propylene oxide have been added in small amounts in the past. Raising the nitro % requires different head volume and some pipe length adjustment. It doesn't increase the rpm, but the boats can run bigger props at the same rpm. As was pointed out before, the nitro increases MEP and therefore torque.

In 26 to 36cc spark ignition, gasoline engines it was found that doubling the recommended oil mix increased power. Again, I suspect most comes from improved sealing of the single ring piston. By the way, it was common with older style 2 ring pistons to remove the bottom ring for more power.

We did a series of dyno tests on a 26cc engine with various fuels. See below. We found that it was hard to beat the standard pump gasolines even with added nitro and/or ethanol and methanol. Nitro mixes very well with ethanol containing "gasoline". Even Coleman fuel at 50 octane ran well. The reason was we didn't/couldn't change the combustion chamber volume, pipe, or ignition timing. All we did was richen the needle settings for peak power. Methanol and nitro fuels have a lot lower exhaust temperatures and need a different pipe. Nitro burns slower and probably could use more advance. The compression ratio of these industrial engines with one piece head and cylinder designs already have too low compression ratios. Head button engines have more power out of the box. We ran some nitro/methanol fuels in a head button engine briefly. The engine ran fine on 15% nitro, but burned off the plug electrodes on 40% nitro. Again we didn't try to optimize the engine for the different fuel since the race rules specify "gasoline". We did run VP's U-2 for record setting. That fuel was pretty far from pump gasoline.

Lohring Miller

337601

[Nath88]

At Orbital, I remember at around the mid 90s when we first fitted the OCP system to a 50 cc Piaggio scooter. This used a 2.5 cc compressor that was driven by a spring loaded piston that was actuated via a roller running on an eccentric on the outside diameter of the engine crank, ingesting its air (and oil) from the crankcase. Once satisfactorily mapped, the thing combusted every cycle. To me it was almost annoying, especially at idle, in that it sounded so busy compared to a (misfiring) carb engine at the same speed.


I think that at closed throttle, with only the crankcase pumping, on each cycle a relatively small amount of air and fuel enters the cylinder, it's then mixed thoroughly with the exhaust gas by piston movement. It can takes a few cycles before the concentration of fresh mixture to inert exhaust gas is high enough to allow combustion.

What I found is that at closed throttle the intake vacuum doesn't vary much with RPM, so the pressure across the throttle plate and throttle orifice are both constant, therefore you get a constant flow rate with respect to time. So at higher rpm you'll see a lot more missed cycles than at idle, but the time between dings is not that different.

With the orbital system you were probably achieving a stratified charge, 2.5cc of air premixed with fuel, in a small pocket not mixed with the exhaust gas. Injection at the top of the cylinder means the pocket would be concentrated at the spark plug, allowing for fire every cycle.

I've almost finished porting my cylinder, it'll be receiving Uncle Flettner's B port TPI system. I'll be intercepting the injection pulses from the Microsquirt ECU with a separate controller which will read TPS, RPM and MAP to roughly calculate airflow through the intake, it will then skip injection pulses as required until the cylinder has enough fresh air in it to support combustion. The idea is to induce the engine misfires instead of trying to react to them in real time.

It will also interleave the 2 injectors at low pulsewidths for extra precision and control the oil and fuel pumps.

The only problem I see is when the injector does fire, a very rich mixture will be delivered through the transfers at the bottom of the cylinder, hopefully it will mix with the cylinder mixture and be combustible.
Even if it takes an extra cycle or 2 to mix it at low throttle % it's probably not a big deal.

[TZ350]

it could be argued that the scavenging gas flow from the injected B ports would take a shorter path out to the exhaust than say the C port, which one could imagine in the Schnurle scavenging system would have the longest path. So, it’d be interesting to inject into this alone rather than the B ports.

I have recently tried these combinations.

C for idling and low speed/power and B+B for high power.
B+B for idling and low speed/power and C for high power.
B one side for power B the other side for idling and low speed/power.
From one side of the crankcase firing directly into the inlet air stream for idling and low speed/power, B+B for high power.
From one side of the crankcase firing directly into the inlet air stream for high power and C for idling and low speed/power.

337602 337603 piston at TDC

C for idling and low speed/power and B+B for high power seems to work best for me.

With the C port on its own for high power it seems to drown when fuel demand gets up. But C works very well for idling and low speed/power.

With C port injection it idles smoothly at 2,000 rpm and with a carb it had to be 3,000rpm .... :scratch:.... another mystery.

[Myles]

In 26 to 36cc spark ignition, gasoline engines it was found that doubling the recommended oil mix increased power. Again, I suspect most comes from improved sealing of the single ring piston. By the way, it was common with older style 2 ring pistons to remove the bottom ring for more power.

Lohring Miller


How much is a doubled amount of oil for those engines?

[Flettner]

may i ask, you ethanol / methanol junkies, what reeds are you running?

[lohring]

How much is a doubled amount of oil for those engines?

The factory recommends 25 to 40 to 1. That's around 3 to 5 US fluid ounces per US gallon. We ran 4 ounces per gallon in the past, but now run 8 to 10 ounces per gallon. Higher than 8 ounces didn't improve power in our dyno testing, but might help the big end bearing live at over 20,000 rpm.

Lohring Miller

[lohring]

If you were asking me, our engines are mostly piston port with a few disk valve specialty engines. The small nitro engines all have rotary valves.

Lohring Miller

[SwePatrick]

may i ask, you ethanol / methanol junkies, what reeds are you running?

Oem Kawasaki KX250 with mods and Polini petals ;)
New V-force is bad,, the petals are getting soft, the resin dissolves.

I tried a boyesen cage with polini petals, no good.
There´s no rubber coating so the petals lands so hard it smashes them.

[Flettner]

Oem Kawasaki KX250 with mods and Polini petals ;)
New V-force is bad,, the petals are getting soft, the resin dissolves.

I tried a boyesen cage with polini petals, no good.
There´s no rubber coating so the petals lands so hard it smashes them.

thats the main reason I switched to the F9 RV engine from the DT360 I was using. Ethanol played havoc with the reeds on the DT.
But now with TPI I'm not sure what might happen?

[husaberg]

thats the main reason I switched to the F9 RV engine from the DT360 I was using. Ethanol played havoc with the reeds on the DT.
But now with TPI I'm not sure what might happen?
Pretty sure i have a 6 petal origional SS IT175 reed valve here Neil.
I can't say if the rubber coating will last though.
Pretty sure it will be the same bolt pattern.

[Grumph]

Pretty sure i have a 6 petal origional SS IT175 reed valve here Neil.
I can't say if the rubber coating will last though.
Pretty sure it will be the same bolt pattern.

YZ reed manifolds held up in 250 kart engines running Methanol/Toluene/Benzole blends. Aftermarket reeds didn't - so got changed frequently.
I believe the "rubber" is the same on all the yamaha reed blocks I've seen.

[TZ350]

Have you seen this one Ken
its a tiny high ultra pressure pump.
https://www.popularmechanics.com/cars/hybrid-electric/a9263/the-20-device-to-replace-dirty-carburetors-15682450/
https://news.engin.umich.edu/2012/09/cleaner-motorcycle-engines-student-startup-inspired-by-growing-emissions-in-asia/
have a look at the fuel spray

https://www.youtube.com/watch?v=UB34NMoBRGA
kind of reminds me of a hilborne system only electric
http://www.freepatentsonline.com/20140117121.pdf

The Uni students all in one motorcycle EFI system looks pretty good, brilliant even and the voice coil injector is a great idea, I love it.

[SwePatrick]

Still testing clutch, now i´m happy.
This tune is good as now i can add springs or loose weights on the clutchfingers to gain different results, more rpm, harder engage etc etc.
The tune in the video is a grandma tune ;)

Yes i have been lazy,, tied up the silencer with a rope, it got loose.
And in front the shiftcut box is hanging by the loom.
I´ll fix that tomorrow.
And this weekend i´ll try to tune the engine some also(dyno)
It is last years tune that i did for the old setup.



https://youtu.be/T6OxnBYPIho

[wobbly]

Using a voice coil system to create the injection fuel pressure ( amplitude and frequency controlled by an ECU ) will infringe a key part of
the Etec patent.
This is the basis of the whole system as used by Evinrude and SeaDoo , im sure they will spit the dummy if their mega expensive licencing is infringed
by attempting to use this commercially.

[husaberg]

Using a voice coil system to create the injection fuel pressure ( amplitude and frequency controlled by an ECU ) will infringe a key part of
the Etec patent.
This is the basis of the whole system as used by Evinrude and SeaDoo , im sure they will spit the dummy if their mega expensive licencing is infringed
by attempting to use this commercially.
Unlikely a patent has been issued.
http://www.freepatentsonline.com/20140117121.pdf
https://patents.justia.com/patent/9500170

I cant see Etec in citation either i assume you are refering to this one?
If it is the one Etec is Piezo?
<dt style="width: 150px; text-align: left; color: rgb(146, 146, 146); text-transform: none; line-height: 21.76px; text-indent: 0px; letter-spacing: normal; overflow: auto; clear: left; font-size: 13.6px; font-variant: normal; margin-right: 5px; word-spacing: 0px; white-space: normal; text-overflow: ellipsis; box-sizing: border-box; orphans: 2; float: left; -webkit-text-stroke-width: 0px; background-color: transparent;">
US 4610427?<strike></strike>
</dt><dd style='background-color: transparent; box-sizing: border-box; color: rgb(0, 0, 0); font-family: "Roboto",sans-serif; font-size: 13.6px; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 21.76px; margin-left: 170px; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px;'><strike></strike>
</dd>
was it patented by
Yoshinaga, T. (https://www.osti.gov/search/author:%22Yoshinaga,%20T.%22); Igashira, T. (https://www.osti.gov/search/author:%22Igashira,%20T.%22); Sakakibara, Y. (https://www.osti.gov/search/author:%22Sakakibara,%20Y.%22); Abe, S. (https://www.osti.gov/search/author:%22Abe,%20S.%22); Natsuyama, Y. (https://www.osti.gov/search/author:%22Natsuyama,%20Y.%22) ?
<dt style='background-color: transparent; box-sizing: border-box; clear: left; color: rgb(146, 146, 146); float: left; font-family: "Roboto",sans-serif; font-size: 13.6px; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 21.76px; margin-right: 5px; orphans: 2; overflow: auto; text-align: left; text-decoration: none; text-indent: 0px; text-overflow: ellipsis; text-transform: none; -webkit-text-stroke-width: 0px; white-space: normal; width: 150px; word-spacing: 0px;'></dt><dd style='background-color: transparent; box-sizing: border-box; color: rgb(0, 0, 0); font-family: "Roboto",sans-serif; font-size: 13.6px; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 21.76px; margin-left: 170px; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px;'>
</dd>

[peewee]

Still testing clutch, now i´m happy.
This tune is good as now i can add springs or loose weights on the clutchfingers to gain different results, more rpm, harder engage etc etc.
The tune in the video is a grandma tune ;)

Yes i have been lazy,, tied up the silencer with a rope, it got loose.
And in front the shiftcut box is hanging by the loom.
I´ll fix that tomorrow.
And this weekend i´ll try to tune the engine some also(dyno)
It is last years tune that i did for the old setup.



https://youtu.be/T6OxnBYPIho

nice work mate. let me know where you sort out the clutch. I also have a finger style that im installing on my Yamaha. I understand the idea how it works but ive never spent a day tuning one. my biggest hurdle might be finding the correct initial weight for the fingers. after that, I shouldn't have much trouble. ive only got weight to worry about, no springs

if you give some nitro a go, you may never go back to straight methanol again :laugh:. even if everything isn't perfectly tuned, you still gain power. but take caution because it can be explosive even at just 10%. it nearly blew my decompression valve off my other head

[Flettner]

Oem Kawasaki KX250 with mods and Polini petals ;)
New V-force is bad,, the petals are getting soft, the resin dissolves.

I tried a boyesen cage with polini petals, no good.
There´s no rubber coating so the petals lands so hard it smashes them.

what are the polini petals made of?
Vforce ? cage get soft also?

[lohring]

For no particularly good reason I've been exploring the idea of a piston ported cylinder with a boost port for a 26 cc engine. I know it's been done before, see below. My design looks weird and simulations don't show any power gains over a cylinder with no boost but a wider B port. Of course scavenging isn't being modeled. Any thoughts or other ideas?

Lohring Miller

337615 337616 337617

[Haufen]

Any thoughts or other ideas?

Don't do it. The BP is the least useful port of all. Focus on B instead if you can choose. I once blocked the BP out of curiosity, and other than half a horse or so (which could be related quite well to the then reduced transfer TA) nothing happened.

[SwePatrick]

what are the polini petals made of?
Vforce ? cage get soft also?

Just petals got soft, but i actually never checked the cage carefully.
It´s the resin in V-force petals that becomes soft, i mailed them and asked, they confirmed.

I dunno what resin polini uses, but they work,, good enough ;)

[SwePatrick]

Today´s progress: FAIL!

Well, one should always be prepared for disaster, and luckily i am so no tears here.

I finally put it on the dyno, engine felt really crisp and fresh, good throttleresponse etc etc after a long warmup.
I made some smaller pulls with no recording just to feel how it behaved with the clutch.
All seemed fine so i was about to make a 5000-11000rpm pull to let it cool down and do it again a couple of times.

But,, at the first pull i noticed at about 10500rpm that it had a small waterleak around a headstud.
BAM!!!! just the tenth of a second later a hose i have plugged to be able to vent out the air when filling with water as the radiator is lower than the cylinder came loose.
I got myself a hot shower on my chest and face, luckily no damage on me,, just hot.
But engine coasted down as i was spitting out the water from my mouth.

It had protruded water into the cylinderbore, and made some smaller scoring on the fresh nicasil.
Maybe it is possible to diamondhone it and use it again, i´ll check that later.

Why did it happen?

i got three enginemounts the lower one underneeth the engine had cracked and when engine hit the torque the engine tilted upwards, the only thing that kept it from rotating was the upper mount, this is mounted in a bracket on the head.
It had actually 'moved' the head some, this probably because i torqued the head only with 15Nm as i was about to torque it again after this pull when it was hot.

337618


Well well,, i´ll be back, it sounded just to good to give up now ;)

[TZ350]

Sorry to hear about the disaster...... :(

When we have disasters we say to ourselves, at least we know the formula because the formula is often more valuable than the damage discovering it.

[peewee]

may i ask, you ethanol / methanol junkies, what reeds are you running?

for atleast a year i been using carbontech. i think its a subsidiary of boyesen. already 1gal nitro and many gallons methanol and they still seem fine . they can also make custom orders
https://www.carbontech.com/

[TZ350]

337622

I have been making progress with the simulated MAP idea.

I have abandoned my original idea of using a MAP sensor to see the high and low pressures because MAP sensors are too slow and instead will use a piezo element.

337619 EngMod2T simulated crankcase pressure traces.

Because all the peak pressures all line up at the same crank angle I have embraced Flettner's idea of "sample and hold" by making only one timed measurement at peak pressure and using that for the complete cycle.

337621

I have been able to use some PC based software to generate a simulated ignition trigger pulse and crankcase pressure trace for my software's test and development purposes.

337620

The code is pretty simple, an interrupt triggered by the ignition trigger pulse at which time it waits about a third of the duration between pulses and then samples the crank case pressure. The loop writes the simulated MAP output signal that then goes to the EFIs CPU.

Simple code but it took a while to get it and my test setup to work reliably over the full RPM range.

[Flettner]

diesel is dead to me. Are we allowd to talk diesel here?
Last diesel ute I had would do just on 1200 km on a tank full of fuel. New diesel ute (same ute just new) gets just on 900 km per tank full, same size tank. Turns out new ute has a partical filter where as the previous one did not. 300 km worth of fuel per tank wasted just to run this filter. WTF?
How soon before Mazdas HCCI are here? How soon before we see HCCI powered utes, I'll be trading this bugger on one.
So what about all the extra CO2 released just to run this filter? Good for the enviroment, I don't think so.

[speedpro]

Less particles, more CO2

[lohring]

Don't do it. The BP is the least useful port of all. Focus on B instead if you can choose. I once blocked the BP out of curiosity, and other than half a horse or so (which could be related quite well to the then reduced transfer TA) nothing happened.

Thanks, that's starting to be my thought as well. Should the B port be angled up around 5 degrees like the traditional design or should it be changed to scavenged the rear wall of the cylinder better? Should the B port hook be the same as with a boost port or should the flow collide straight across with the opposite B port? A successful piston port design I've raced has the B port with a flat top and no hook. Something like the images below.

Lohring Miller

337632 337633

[SwePatrick]

Sorry to hear about the disaster...... :(

When we have disasters we say to ourselves, at least we know the formula because the formula is often more valuable than the damage discovering it.

Now i have taken it apart and measured it.
I cannot actually measure any damage so it´s worn under 0.005mm as max.
So i think it is possible to save it, i will have a engineshop diamondhone it and put a new ring into it, piston is ok.

Some kind of luck in all the bad luck ;)

[wobbly]

If an engine looses only a tiny amount of power if the scavenging regime is changed by blocking the B.P than all that means is the A & B scavenging system was very wrong to start with.
Running a modern setup with near flat ,huge B ports with a rear wall hook, along with smaller A ports that effectively axially jump over the B port columns, there is no way that
flow regime can create a correct " leaning tower " up the back wall with no B.P directional control included.
By definition a 4 port must have greater axial up angles and no way could you use a front B port wall that is radially perpendicular - like Jan developed at Aprilia.
What we regard as normal axial and radial angles nowdays in a 5 port were slowly and meticulously changed over time to give the highest scavenging efficiency along with a high
trapping ratio - simply deleting the B.P in this setup ( and thereby assuming it does nothing due to no power loss ) would be saying in effect that all that development was a complete waste of time
and a huge effort should have been directed at 4 ports all along - dont think so.
If a B.P makes so little difference to a good 5 port scavenging system, why does it make a huge impact when you cut a radius on the piston timing edge.
I havnt done the test of leaving the edge in front of the B.P uncut , but reports are that it works very well.
All I do know so far from tests is that a radius big enough to make the B.P flow attach to the piston ( and thus less to the rear wall ) kills power badly.

[ken seeber]

ETec Direct injection.
OMC (Johnson & Evinrude) first released the Ficht DI system in 1996. This turned out to be a techo disaster with OMC filing for bankrupcy in 2000. Taken over in 2001 by Bombardier, the Evinrude was released in 2004 with a refined & properly developed Ficht system called Etec.
So, 22 years later, I reckon it’d be reasonably safe to have a play without having lawsuits or just suits arriving with the 2nd Amendment behind them. I think patent life in the US if 20 years and Oz it is 17.

337638337639

[Haufen]

If an engine looses only a tiny amount of power if the scavenging regime is changed by blocking the B.P than all that means is the A & B scavenging system was very wrong to start with.
Running a modern setup with near flat ,huge B ports with a rear wall hook, along with smaller A ports that effectively axially jump over the B port columns, there is no way that
flow regime can create a correct " leaning tower " up the back wall with no B.P directional control included.
By definition a 4 port must have greater axial up angles and no way could you use a front B port wall that is radially perpendicular - like Jan developed at Aprilia.
What we regard as normal axial and radial angles nowdays in a 5 port were slowly and meticulously changed over time to give the highest scavenging efficiency along with a high
trapping ratio - simply deleting the B.P in this setup ( and thereby assuming it does nothing due to no power loss ) would be saying in effect that all that development was a complete waste of time
and a huge effort should have been directed at 4 ports all along - dont think so.
If a B.P makes so little difference to a good 5 port scavenging system, why does it make a huge impact when you cut a radius on the piston timing edge.
I havnt done the test of leaving the edge in front of the B.P uncut , but reports are that it works very well.
All I do know so far from tests is that a radius big enough to make the B.P flow attach to the piston ( and thus less to the rear wall ) kills power badly.

You are right, that cylinder of mine was not really state of the art. And neither is lohring's from what I can see at his pictures. I'd still give it a try.

The loop scavenged engines with the best trapping efficiency (by far) are 4 port and used in gardening and forresting. These can reach up to 96% without an expansion chamber pushing the charge back. If they wanted to have a BP, they could. But they don't.

I assume that the radiused edge on the BP area increases scavenging losses by directing part of the BP charge directly out of the exhaust port as it attached to the crown. This would be very likely not to come back by the exhaust port as it is lost very early in the cycle. Were there any clues (max EGT for peak power difference?, jetting etc? - anything that indirectly hints to trapping efficiency) this might have happened? So to answer your question on "why does it make a huge impact when you cut a radius on the piston timing edge": because it allows for more scavenging losses as you allow charge to shoot throug the basement of the tower. If you just close the BP, that is a different mechanism: the tower may lean a bit more away from the exhaust port - which has the potential for very high trapping efficiency (see chansaws, blowers, trimmers etc.).

As the development direction has made the BP smaller and smaller over the years. Why not max this out by trying something a bit brave? Compared to the other ports, the BP offers far less TA vs. the bore area it uses. If you could block the BP on the TM with a gasket, and rejet if necessary, to get a first impression on a modern 2T, that'd be really cool. To verify or falsify my hypothesis on the working mechanism, you could then also try a blocked BP in combination with the radiused piston if the results turn out well with the blocked BP and normal piston. What do you think?

[Greg85]

Hi Jan, I have been flat out building test pipes for TM, as well as doing the record breaking 350cc Pre 81 Land Speed Project at Bonneville.
Thus I have not been able to remove the test cylinder from the dyno to get it coated.
Franco is way too secretive to tell me I think, if his non cooled duct was a failure or not.
But i will ask, as soon I have a result to show him - wont be long.
I had originally been obsessed with getting over 50 Hp along with plenty of overev power, but the 30mm carb seems to prevent any real
extra peak power.One pipe made 49.6 and had 6 more at 14500, but on track that was barely faster.
So I have been hard at work trying to get more front side power, ie going up to the peak.
Here is where I am at now, and building/dynoing this pipe today.

hi wobbly I just bought engmod 2t I would like to have some info if possible of course, about a simulation of the engine tm kz10b stock,a reference value in hp you find how much engine stock simulate?default values to enter combustion,temperature,thank you

[wobbly]

I dont have a B model TM on this computer, it was stolen from my workshop several years ago.
But here is a C model pack.The modelling is all but identical apart from the pipe - easy to change.
It uses the step updated function correctly for the header and the stinger.

Blocking the C port isnt on the radar, as it would be illegal to change the number of ports in the cylinder.
I may get away with a gasket blocking it though.
But I dont understand how a 4 port creates a " better " trapping efficiency, as I said before to create a good scavenging loop the radial and axial angles
must be steeper ( as you dont have a boost port attaching the flow to the rear wall).
Thus with the steeper axial angles , the loop length is shorter, giving more short circuiting opportunity in the time frame from EPO to EPC.
And again with no rear wall flow attachment , the loop would tend to angle more toward the Ex port, unless the radial angles are very steep, creating again a shorter loop time.
My belief would be that the scavenging efficiency would be far more compromised, so even with a really good trapping efficiency, less power would be the result - due to the trapped charge being Ex gas diluted..
Yes you are right the bigger radius on the piston had lower EGT,and with a 2 jet change it came back, but the power didnt.
Repeatably CNC cutting a radius on the piston, with a gap left stock, needs a radius form tool in a 5 axis , way too much time, money and effort at this stage - especially with the huge gains
I found by simply doing the Ex duct correctly.

Bugger I cant post a .pack file , can this be changed or do I have to keep .zip it.

[lohring]

I just got a much better idea on another forum. If I run a divided intake port I can feed the boost port with a hole in the piston. See below.

Lohring Miller

337660

[Flettner]

just as an aside I guess but I did once change my DT360 so as to have no boost port as such. The port was changed so as to point forward straight towards the exhaust port, flat delivery and timed slightly less than the other ports. The idea being that the A ports flow would catch this C port flow and send it up the back of the cylinder with everything else.
Did it go any better? Seat of the pants dyno so who knows ulitamtely but it feel like it had more power and wider power spread, certainly didn't have any less.

[Greg85]

I dont have a B model TM on this computer, it was stolen from my workshop several years ago.
But here is a C model pack.The modelling is all but identical apart from the pipe - easy to change.
It uses the step updated function correctly for the header and the stinger.

Blocking the C port isnt on the radar, as it would be illegal to change the number of ports in the cylinder.
I may get away with a gasket blocking it though.
But I dont understand how a 4 port creates a " better " trapping efficiency, as I said before to create a good scavenging loop the radial and axial angles
must be steeper ( as you dont have a boost port attaching the flow to the rear wall).
Thus with the steeper axial angles , the loop length is shorter, giving more short circuiting opportunity in the time frame from EPO to EPC.
And again with no rear wall flow attachment , the loop would tend to angle more toward the Ex port, unless the radial angles are very steep, creating again a shorter loop time.
My belief would be that the scavenging efficiency would be far more compromised, so even with a really good trapping efficiency, less power would be the result - due to the trapped charge being Ex gas diluted..
Yes you are right the bigger radius on the piston had lower EGT,and with a 2 jet change it came back, but the power didnt.
Repeatably CNC cutting a radius on the piston, with a gap left stock, needs a radius form tool in a 5 axis , way too much time, money and effort at this stage - especially with the huge gains
I found by simply doing the Ex duct correctly.

Bugger I cant post a .pack file , can this be changed or do I have to keep .zip it.
Hi wobbly thanks a lot for the file, with you I saved time ,however I would like to know how you have done to measure all the ignition data?you are on new engine project at this time?TM new approval?in any case a big thank you for your help and all your posts every time very interesting

[Haufen]

Blocking the C port isnt on the radar, as it would be illegal to change the number of ports in the cylinder.
I may get away with a gasket blocking it though.
But I dont understand how a 4 port creates a " better " trapping efficiency, as I said before to create a good scavenging loop the radial and axial angles
must be steeper ( as you dont have a boost port attaching the flow to the rear wall).
Thus with the steeper axial angles , the loop length is shorter, giving more short circuiting opportunity in the time frame from EPO to EPC.
And again with no rear wall flow attachment , the loop would tend to angle more toward the Ex port, unless the radial angles are very steep, creating again a shorter loop time.
My belief would be that the scavenging efficiency would be far more compromised, so even with a really good trapping efficiency, less power would be the result - due to the trapped charge being Ex gas diluted..
Yes you are right the bigger radius on the piston had lower EGT,and with a 2 jet change it came back, but the power didnt.
Repeatably CNC cutting a radius on the piston, with a gap left stock, needs a radius form tool in a 5 axis , way too much time, money and effort at this stage - especially with the huge gains
I found by simply doing the Ex duct correctly.

It would be really good to have a calibrated CFD model now. Do TM happen to have one? When I was working on low emission two-stroke engines (I am sure you'd excel at it, as it is just like tuning for power, just the other way round: keep the power the same and improve trapping efficiency), I had access to all the results from the CFD supercluster computer in Italy and spent part of my time at work to "watch" scavenging videos of different engines at various configurations and engine speeds, analysing the scavenging pattern, cutting the model into sections, playing back and forth etc., until I was sure I had learnt everything there was to learn from. You could even see the small wave from the back wall of the box exhaust returning at the exhaust port. From what I learned I'd say that steeper axial angles might not even be necessary as the bulk flow starts at around BDC and the upward moving piston then supports the scavenging regime on the way up.

I found the side view of a 4 port scavenging on youtube - if you stop the video at 4s, you can see the column leaning to the left before starting the loop. If there were a BP, then the column would be more straight and hence closer to the exhaust port. Depending on the engine speed and loop speed (and pipe geometry), this may or may not be beneficial, but even if you had the same amount of charge inside the cylinder after EPC, the charge which had not taken the trip into the exhaust port and back (no matter how well it is cooled), will likely be cooler.

And because of this, and because decades of scavenging developments point to making the BP smaller and smaller, and because it can be done rather quickly by just blocking it with a gasket, I think this is worth giving a try. Of course it won't be perfect at first try, but it might already show some potential (e.g. by losing less power than what might be expected from the TA difference).

4 port scavenging on youtube
https://www.youtube.com/watch?v=3F_0PvbKo44

exhaust port view for completeness:
https://www.youtube.com/watch?v=M53nersJJ3o

[wobbly]

Generating the combustion file is easy to do - the ignition timing is fixed, as is the A/F ratio.
Run your model as completed in Turbulent Model mode - very slow as the crunching is huge.
Then in Post, open that last file to choose what parameters you want to see, you will then see on the right hand side a radio button
for " Write Combustion File ".Activate that, and save it with a new name ( I always call it Turb ).
Make sure it ends up in 2Stroke folder, not in the project one.
Then you can choose that new Combustion file when opening the project.
This then uses all the data generated by the Turbulent run, but now you can run Prescribed every time - way way faster.

I was given the job of developing the next TM homologation pipe in secret , away from Italy , as it costs them a fortune to have 1 offs made , and nothing is secret if enough money changes hands.
That job I completed with a really big gain, on the dyno , and Franco/DeConto track tested it as well.
Elto have made test pipes from my CAD patterns , but no one has seen the actual straight line drawing - and no one will untill the homologation papers are signed off.
Slowly I have gained enough credibility with them to get more detailed work, but there are very big ego's involved of course as they are the current World Title holders ( so dont need me involved ).
But I keep making more power than they do , so I just keep on doing it to annoy them.

Haufen, no TM dont have a CFD setup, they should as they use NX as a CAD platform.I have their full solid model of the C cylinder so I could use it in the SolidWorks
CFD package, but hell I find it hard to keep up with work as it is , without trying to learn a new platform as well.
But for sure I will try a blanking gasket and see the changes in the dyno data , and go from there.

[Nath88]

I'm almost done porting my 2.1mm overbore YZ250 cylinder, the port windows are where I want them, using a laser cut port template, Main exh: 190, Aux exh: 185, A:122, B:121 and C:119.
Exhaust is widened to the full width of the powervalve blade. The A ports are about 2mm wider toward the exhaust port to get the required transfer TA. I smoothed the Boyesen passages and kept the septums rounded.
Tidied up casting flash everywhere but left the intake and transfers with a rough finish.
Main and aux exhaust ducts cleaned up and blended, not quite polished but smooth.

I've left the radial transfer angles as standard.
I measured the standard axial angles as A:16 and B:14. After porting I have angles of A:22 and B:15. Frits' calculation gives values of A:26 and B:12

Looking for some advice on where to go from here, should I:

Flatten out the A ports to 16 degrees to return to standard configuration,
Flatten out the B ports to 12 to closer align with Frits' values, or;
Leave them how they are right now, as some sort of compromise?

What would be the effects of the above options?
My goal is to move the power curve up about 800rpm, powerband width is important since it's a street motor with a 5 speed box.

337666337664337665337663

[wobbly]

I would lift the A port to increase the angle and the duration.
More stagger = wider bandwidth.
If you want more Blow STA to match, then the Aux port roofs can go alot closer to the main.

[husaberg]

I would lift the A port to increase the angle and the duration.
More stagger = wider bandwidth.
If you want more Blow STA to match, then the Aux port roofs can go alot closer to the main.

I have been meaning to ask you wob just how big were the reeds on the BSL I looked at a pic the other day and they seemed to fill the whole gap between the bore centers?
I was looking at a pic of the NSR500 the other day and even that was compromised In the effective width as they were still offset which I never expected with there wide centers dud to the single crank.
I am picking they were much larger than the RS125s other wise there should have been more room.
The BSL on the other hand looks symmetrical.

[wobbly]

The BSL had late model TZ250 reed blocks, that were not symmetrical pyramids - but angled upward under the cylinder.
From memory they had nearly 40% more port area than the CR/RS125.
I tried VeeForce as they were keen to sponsor us, but the petals fretted in no time.

[husaberg]

The BSL had late model TZ250 reed blocks, that were not symmetrical pyramids - but angled upward under the cylinder.
From memory they had nearly 40% more port area than the CR/RS125.
I tried VeeForce as they were keen to sponsor us, but the petals fretted in no time.

Cheers by symmetrical I was meaning the reed cavity were all the same shape and position and layout. only reversed for the lower cylinder of course.
pics to follow.
bugger I cant find the decent pic of the engine in the frame I seen the other day.
V angle 110-120?
337671337672 BSL500

337669337670NSr500
337667YZR500
337668Added the Roberts three just cause I could, looking at it. it looks like it has the reds spun 90 degrees like a NSR250
this version below of the Roberts three has the pump around carbs and pretty low tech fabricated rubbers plus either they swapped the two up one down or this ones carbs are upside down
my moneys on it being upside down
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=321627&d=1463388722

[Muhr]

Haufen, no TM dont have a CFD setup, they should as they use NX as a CAD platform.I have their full solid model of the C cylinder so I could use it in the SolidWorks
CFD package, but hell I find it hard to keep up with work as it is , without trying to learn a new platform as well.
But for sure I will try a blanking gasket and see the changes in the dyno data , and go from there.

I would have loved to put my hands on that file and see what one can find out

[lohring]

Below is an article I edited to help explain two stroke scavenging. It includes a series of CFD pictures of Aprilia 125 cylinder scavenging flow.

Lohring Miller

337673

[guyhockley]

337668Added the Roberts three just cause I could, looking at it. it looks like it has the reds spun 90 degrees like a NSR250
this version below of the Roberts three has the pump around carbs and pretty low tech fabricated rubbers plus either they swapped the two up one down or this ones carbs are upside down
my moneys on it being upside down
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=321627&d=1463388722

In the Mike Sinclair book he talks about the early KR triples being a flying web v-twin with the third pot added on, then he left when they redesigned it as a Honda style v3. Can't remember if they changed the 2 up or 2 down configuration but I think, maybe, the picture you linked to is the "mark 1" and the picture you posted is a "mark 2"?

[wobbly]

The BSL reeds were 68mm wide ( this is the size that VeeForce make for most 250cc cylinders ).
But as it turned out the TZ250 reeds were just right.
The engine was designed around having these reeds across in line , and the cylinder centers were based on keeping symmetry.
As it turned out I should have made the whole thing 15mm wider , and not used an integral crank pin , as this proved impossible to build reliably without forging or NASA steels.
The reason being that for the best compromise between rotating mass , and balance force reduction , the firing order was No1 LH at 0* then the middle down and
RH upper together 120* later ( 120 Vee angle ).
This produced a torque harmonic across the driving crank pins , and even with big rads and bead peining , they cracked.
Using all press fits fixed it immediately.
With a balance shaft driven of a gear between the common firing pair ( also went out to the clutch ) there was no resultant primary imbalance , only a constant radial force on the mains.
It had no vibes at all, and as the always forthright King Kenny said to his team whilst hanging onto a footrest - you cunts aint got no clue , these guys can do balancing , you dont.

[husaberg]

In the Mike Sinclair book he talks about the early KR triples being a flying web v-twin with the third pot added on, then he left when they redesigned it as a Honda style v3. Can't remember if they changed the 2 up or 2 down configuration but I think, maybe, the picture you linked to is the "mark 1" and the picture you posted is a "mark 2"?
I typed a reply but it wouldn't save
Lozza posted something about the two models or both were designed by a Japanese one was okay the other wasn't
i came across these pics from Kenny ranch either they are mock up or he had some plastic cases i guess its a mock up engine.
they look to be CNCed rather than cast resin
337678337679


The BSL reeds were 68mm wide ( this is the size that VeeForce make for most 250cc cylinders ).
But as it turned out the TZ250 reeds were just right.
The engine was designed around having these reeds across in line , and the cylinder centers were based on keeping symmetry.
As it turned out I should have made the whole thing 15mm wider , and not used an integral crank pin , as this proved impossible to build reliably without forging or NASA steels.
The reason being that for the best compromise between rotating mass , and balance force reduction , the firing order was No1 LH at 0* then the middle down and
RH upper together 120* later ( 120 Vee angle ).
This produced a torque harmonic across the driving crank pins , and even with big rads and bead peining , they cracked.
Using all press fits fixed it immediately.
With a balance shaft driven of a gear between the common firing pair ( also went out to the clutch ) there was no resultant primary imbalance , only a constant radial force on the mains.
It had no vibes at all, and as the always forthright King Kenny said to his team whilst hanging onto a footrest - you cunts aint got no clue , these guys can do balancing , you dont.
Cheers Wob

[wobbly]

The first engine was designed by the Honda engineer that did the Freddie tripple.
It was a disaster , too long ( gearbox shafts on the horizontal split line ) and Bud Askland had to grind huge amounts out of the case ( right down to the main bearings )
to get close to the correct volume.
It vibrated like hell , I simply could not hold the throttle with a bare hand it hurt so much.
The later engines were done at the Roberts facility in England using much better technology.

[lohring]

I like this version of the piston port with boost port better.

Lohring Miller

337681 337680

[ken seeber]

Lohring,
The one thing to be considered here is that if the piston skirt length is set to suit the inlet timing, then this skirt length would be wrapped around to the side of the piston, into the area normally left open as the cutaway to feed the transfers. From what I can seem the B port and some of the A would have the piston skirt interfering with the crankcase to transfer passage entry flow. Of course, this might be dependent on the overall engine design though in terms of the designed piston length.

[husaberg]

The first engine was designed by the Honda engineer that did the Freddie tripple.
It was a disaster , too long ( gearbox shafts on the horizontal split line ) and Bud Askland had to grind huge amounts out of the case ( right down to the main bearings )
to get close to the correct volume.
It vibrated like hell , I simply could not hold the throttle with a bare hand it hurt so much.
The later engines were done at the Roberts facility in England using much better technology.

I found Lozzas post which covers the second version.
I must admit i am struggling to get my head arround your description of the BSL crank layout but i might have to draw it.
Honda had formula they used on the narrow angle offset crankpin twins like the bros Hawk and VT500.
If i recall corectly it went along the lines of 1/2 the v angle -90 dregrees equals the crank pin offset to make it think its a 90 degree v twin.
I am not sue but i think for over 90 degrees it might work out to be 180 - the v angle?
I could never figure out how Two bros used to get those cranks which are effectively flying web, to last a big revs, well it turns out they couldn't no mater what they tried they just threw a new one in every race. Pretty sure Hondadid the same with the RS750 that used to run flat track.


Okay maybe not here is the formula they used in the sales ads

he XRV 650 engine is a V twin-cylinder, with the pistons at the angle of 52o (see the picture bellow). According to the formula “V= 180-(2 x 52) = 76”, invented and applied by Honda, the corresponded angle between the piston-rods is of 76o. That means a crankpins offset of 76o, resulting in a better mechanical balance and subsequently reducing vibration and other stresses. Thus compensates the mechanical design compared to a V-twin engine with an angle of 90°, which inherently gives a very good mechanical balance. Due to specific crankpins offset, applied on the engine of Africa Twin, no balance shaft is required. The elastic collars of the engine mounting are adequate for the amortization of the inherent to motor’s design
337683


Roberts fell flat on his arse when he had a go of making his own engine. Wasn't until he hired (ironicaly) Oguma-san and ex Yamaha GP engineer Yoda-san(I forgot his firstname) they redesigned the engine to be shorter, narrower and increased the V angle and incorporated a balance shaft did that Modenas start to go like a GP bike. The shorter and narrower engine allowed a longer swing arm which gave better traction made it handle like a GP bike. That all came to naught when the 4T rules were announced a short while later . In which the cycle began again, best results were with the HRC V5 and some pointers on frame flex.
HRC always seem to perform best when there is a stern hand on the rudder, though with a smart cookie like Nakamoto they should be winning for some time to come.

.

[lohring]

Lohring,
The one thing to be considered here is that if the piston skirt length is set to suit the inlet timing, then this skirt length would be wrapped around to the side of the piston, into the area normally left open as the cutaway to feed the transfers. From what I can seem the B port and some of the A would have the piston skirt interfering with the crankcase to transfer passage entry flow. Of course, this might be dependent on the overall engine design though in terms of the designed piston length.

You're right, but I haven't got that far along into my layout. We do cut away the piston skirt around the wrist pin area with the normal 4 transfer design, but the inlet port is much smaller. The power level I'm looking for, over 10 hp at 18,000 rpm or so, needs a big inlet port. It probably means I'll need a custom piston and a rethinking of the transfer entries in the crankcase. I'm also wondering what is a good way to model the profiled intake port in EngMod. At present I'm using two trapezoid shaped ports with the same area and similar top and bottom lengths. However, this gives a smooth transition from beginning to full opening.

Lohring Miller

[wobbly]

Husa , put simply the LH cylinder fires first, then the other two fire together 120 later.

[wobbly]

Tried a trick on the 30mm Dellorto carb off the KZ2 engine.
We used to do this on Rotax kart engines before it was banned and a measuring tech tool introduced.
Lowering the height of the emulsion tube shroud , works great in classes where the jetting is limited or fixed.

This is supposed to reduce the low pressure vortex created behind the shroud , thus leaning out the mixture as air flow increases.
The dyno showed it did exactly that , but in this case when the jetting is changed to replicate the egt at peak Hp there is no advantage to be had.
Bugger.

[flyincat]

Hi all, first post here! Greetings from the far side of the pond. Number one, amazing thread and unreal info sharing. Thank you!!

These parts of the world are snowmobile country, so I hope you can forgive me for bringing non-bike material. I've been interested in resurrecting some 70's, 80's, and 90's vintage twin cylinder 2T snowmobile engines, which somehow lead me to the endless 2T info here.

Lohring - having searched and searched for piston port info, I was excited to see you post something recently about a piston port project. Here are some pictures you might find interesting, or not. This is from a Arctic Cat (Suzuki) 500cc twin, case reed, single exhaust port, non power valve motor, ~85-90hp @ ~7800-8000rpm. Not much for performance, but I've seen references that it is intentionally limited in design, and power, to race in a 85hp class. Anyway, the lack of boost port, aside from being case reed, looked quite similar to one concept you proposed. Maybe the port layout is helpful? Just an FYI, but performance shops are porting these engines, along with supporting tuning adjustments, and making 105+hp @8200-8500rpm. I wish I could see a picture of a ported cylinder. There may be a hint in the rear of the cylinder, where it is boxed off. This is the same as the big brother motors (600cc & 800cc), except this boxed in area on the bigger engines houses a boost port along with coolant passages to the crankcase. In this 500 cylinder, there are two coolant passages and a lot of space between them, and space between B ports. Perfect place for a boost port?

[TZ350]

.
Hi Flyincat, very interesting cylinders. Being a temperate climate and not much snow we don't usually see 2T snowmobile engines here. So its very interesting to see what people do with them.

[husaberg]

Hi all, first post here! Greetings from the far side of the pond. Number one, amazing thread and unreal info sharing. Thank you!!

These parts of the world are snowmobile country, so I hope you can forgive me for bringing non-bike material. I've been interested in resurrecting some 70's, 80's, and 90's vintage twin cylinder 2T snowmobile engines, which somehow lead me to the endless 2T info here.

Lohring - having searched and searched for piston port info, I was excited to see you post something recently about a piston port project. Here are some pictures you might find interesting, or not. This is from a Arctic Cat (Suzuki) 500cc twin, case reed, single exhaust port, non power valve motor, ~85-90hp @ ~7800-8000rpm. Not much for performance, but I've seen references that it is intentionally limited in design, and power, to race in a 85hp class. Anyway, the lack of boost port, aside from being case reed, looked quite similar to one concept you proposed. Maybe the port layout is helpful? Just an FYI, but performance shops are porting these engines, along with supporting tuning adjustments, and making 105+hp @8200-8500rpm. I wish I could see a picture of a ported cylinder. There may be a hint in the rear of the cylinder, where it is boxed off. This is the same as the big brother motors (600cc & 800cc), except this boxed in area on the bigger engines houses a boost port along with coolant passages to the crankcase. In this 500 cylinder, there are two coolant passages and a lot of space between them, and space between B ports. Perfect place for a boost port?
Some models of Suzuki artic cat cylinders bolt onto RGV250's. I think its the 660ZRT triple or similar, is it possible to measure the stud spacing to see if it cross pollinates with the say RM250?

[tdc211]

I been playing with pipes and b ports. More so the b port in these pics. Me and a friend had a discussion on the scavinging of this engine. So less B port width was talked about and tried. . It surly was not optimal pipe/head But here is back to back pulls on b port width. Wider b port (no epoxy)
Waz best . But obviously there is a sta difference as well.

Over a year ago. I was building this eng at 34hp with a 790mm pipe. Not big in diameter . Lots comp. Was a easy pipe to obtain and lengthen easily. Always was 20hp at 9000.
One time i decided to mold the b ports better. I always widened them. And epoxy in inner and outer walls in them.
But this one time i added more epoxy in b port. And checked with molds. It was pretty much the same width and length (skinny) till the bore than it got wide. Lots epoxy! It added 3hp at 9000rpm. 23hp @ 9000. More than you can sim with that pipe. I honestly thought dyno was broke. Or the weather station was broke. And hurt peak by 2hp. Same peak rpm. Clutch confirmed dyno result as it had a very hard time holding the pwr. In the mid. i even turned off weather station and inputed the weather. Same thing. Had light detno so i added some export width. Not much diff iin pwr. Probably needed stinger open up. Or head change
Wish i had more time to play with it and see what could be done with it.

Now a year later i know it takes 830mm pipe to make that mid.
With normal looking ports tunnels/with wide ports at bore. And that pipe hurts rpm. Idk. Just a experience i had.

[flyincat]

As a followup to the 500cc snowmobile cylinder pics I posted, here are some of the 'big brother' 600cc cylinder pics. In comparison, note the 600cc cylinder has boost port, powervalve, triple port, 'semi' direct injected cylinder (boost port injected), ~120hp in stock form. It does look like the B port takes up more real estate on the 600 cylinder with the boost port. Just to clarify, both the 500cc and 600cc cylinders are off late models, 2011'ish-present.

TZ350 - you may have seen this video already, but it shows an animation of the boost port injection. It's interesting how the oil is injected into the fuel and runs through the injector. https://www.youtube.com/watch?v=OTGS9kuztcg

[lohring]

I believe the picture I posted as my inspiration was possibly for a snow mobile cylinder. It came from up north ( in North America, not New Zealand). I will need to narrow up the intake port bottoms and increase the intake timing in my cylinder layout. I'll play around with some ideas and lay out the complete engine.

Lohring Miller

[Dutch Fisher]

.......... Other interesting thing from drawings is about EX configuration: looks like one big EX with satellites ,but maybe two big with sat. like on VJ23.
And 3 stages power valve.



As far as i can tell its been a single main ex with 2 aux since the start of the V-4, here's a 1993 cylinder attached, with curious narrowing of the top of the port which could be 'filled' with the static blade of the PV




Honda had formula they used on the narrow angle offset crankpin twins like the bros Hawk and VT500.
If i recall correctly it went along the lines of 1/2 the v angle -90 dregrees equals the crank pin offset to make it think its a 90 degree v twin.



The formulas are : The optimum angular crank pin offset is simply: ( 2 x Av - 180 ) where Av is the angle between the V.
The optimum balance factor is equal to: ( sin(Av) )


Examples: V2 90* = 0* + 100% TZ250(with balancer for rocking couple) RGV VJ22(without balancer)
V2 75* = 30* + 96.5% RS250R nx5/nxa(with bal for RC)
V2 100* = 20* + 98.5% NSR500V(with bal for RC?)
V2 70* = 40* + 94% RGV VJ23(with balancer)***

*** However the VJ23 is 30* offset and has a balancer with an amount of primary? counterbalance on it, with is a might bit strange.


Anyone got the details of the XR95-XR98 Gp250 bike that the marketing hype says the 23 is 'based' on?

[husaberg]

As far as i can tell its been a single main ex with 2 aux since the start of the V-4, here's a 1993 cylinder attached, with curious narrowing of the top of the port which could be 'filled' with the static blade of the PV





The formulas are : The optimum angular crank pin offset is simply: ( 2 x Av - 180 ) where Av is the angle between the V.
The optimum balance factor is equal to: ( sin(Av) )


Examples: V2 90* = 0* + 100% TZ250(with balancer for rocking couple) RGV VJ22(without balancer)
V2 75* = 30* + 96.5% RS250R nx5/nxa(with bal for RC)
V2 100* = 20* + 98.5% NSR500V(with bal for RC?)
V2 70* = 40* + 94% RGV VJ23(with balancer)***

*** However the VJ23 is 30* offset and has a balancer with an amount of primary? counterbalance on it, with is a might bit strange.


Anyone got the details of the XR95-XR98 Gp250 bike that the marketing hype says the 23 is 'based' on?
there was a write up in classic racer about 3-4 months ago
I have a copy but i havent scanned it yet. Not a scan but this will do for now.:laugh:
Pretty sure i have some period pics.
337721337722337723337724

[Norman]

Hi,
In this Racers magazine (No 25) about RGV250 (includes XR95-XR98) there is also some technical information. However, it's in japanese, but to me the pictures looks nice anyway.. I have attached some. Maybe possible to use a "text in picture translation app". I tried that but was not so successful at the time.





As far as i can tell its been a single main ex with 2 aux since the start of the V-4, here's a 1993 cylinder attached, with curious narrowing of the top of the port which could be 'filled' with the static blade of the PV





The formulas are : The optimum angular crank pin offset is simply: ( 2 x Av - 180 ) where Av is the angle between the V.
The optimum balance factor is equal to: ( sin(Av) )


Examples: V2 90* = 0* + 100% TZ250(with balancer for rocking couple) RGV VJ22(without balancer)
V2 75* = 30* + 96.5% RS250R nx5/nxa(with bal for RC)
V2 100* = 20* + 98.5% NSR500V(with bal for RC?)
V2 70* = 40* + 94% RGV VJ23(with balancer)***

*** However the VJ23 is 30* offset and has a balancer with an amount of primary? counterbalance on it, with is a might bit strange.


Anyone got the details of the XR95-XR98 Gp250 bike that the marketing hype says the 23 is 'based' on?

[Dutch Fisher]

Hi,
In this Racers magazine (No 25) about RGV250 (includes XR95-XR98) there is also some technical information. However, it's in japanese, but to me the pictures looks nice anyway.. I have attached some. Maybe possible to use a "text in picture translation app". I tried that but was not so successful at the time.



I can translate with Japanese OCR software, however the pages have to scanned (not photo'd) at hi-res (1920x1080 600dpi) as the jap kanji and kana tend to 'bleed' on anything lower.

[Frits Overmars]

For no particularly good reason I've been exploring the idea of a piston ported cylinder with a boost port for a 26 cc engine. I know it's been done before, see below. My design looks weird and simulations don't show any power gains over a cylinder with no boost but a wider B port. Of course scavenging isn't being modeled. Any thoughts or other ideas?
337615 337616 337617<aside class="ipsComment_author cAuthorPane ipsColumn ipsColumn_medium ipsResponsive_hidePhone" style="box-sizing: border-box; display: table-cell; position: relative; vertical-align: top; padding-right: 0px; padding-left: 0px; width: 200px; text-align: center; color: rgb(53, 60, 65); font-family: Roboto, &quot;Helvetica Neue&quot;, Helvetica, Arial, sans-serif; line-height: 18px; padding-top: 15px !important; padding-bottom: 15px !important;">



</aside>Lohring, we once tried the Aermacchi system of a C-port, fed from the crankcase through a fat intake divider:
http://www.pit-lane.biz/t7437p75-oldies-les-aermacchi-deux-tempsAfter testing it, we filled the lot with Devcon, removed the divider and gained power.
337732
I'd like to suggest staying with your original four-transfer layout. There will be less problems in finding sufficient intake area, less need for additional material, asier to produce, more guidance at the piston ring gap, less wall friction and less heat-excanging surface.
337733


I think this is the post Frits tried to put up - MT (http://twostroketech.com/index.php?/topic/5661-26-cc-cylinder)

Lohring, we once copied the Aermacchi system of a C-port, fed from the crankcase through a fat intake divider: http://www.pit-lane.biz/t7437p75-oldies-les-aermacchi-deux-temps
After testing it, we filled the lot with Devcon, removed the divider and gained power.

I'd like to suggest staying with your original four-transfer layout. There will be less problems in finding sufficient intake area, less need for additional material, asier to produce, more guidance at the piston ring gap, less wall friction and less heat-excanging surface.