ESE's works engine tuner

[TZ350]

349429

Thanks to everyone for the helpful suggestions, they all made sense.

349430349431

I have now modified the air correction and idle air on the carb with replaceable jets to make it easier to find the optimum air correction. I also now have a programmable digital ignition so I can bend the ignition curve for a bit of drive out of the corners and pipe heating for over rev.

Once I get the ignition installed I will get it on the dyno to see what the effect is and if I can duplicate the Red line in the over rev area.
.

[speedpro]

A combination of the power curves will be nice, the good bits of course.

[TZ350]

A combination of the power curves will be nice, the good bits of course.

Yes. Going to see what can be done. I am currently converting a Chinese magneto thing to a generator to power the programable ignition. Basically it will be just a push and go system. No battery just generator, voltage rectifier/regulator, capacitor and DC-CDI programable ignition that creates its own CDI charge from the 12V DC power supply.

Making a decent ignition from a Chinese aftermarket thing:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1681?p=1131033289#post1131033289

[Muhr]

Hey all! Bought a chainsaw today. wanted double the price if I would get one with 3hp instead of 2hp. started it and did not feel so fun, maybe I can fix it a bit (did I sketch on an exhaust) ... Are there any here who have fumbled with chainsaws? Also had carburetor lying around. It's a 35cc.

[F5 Dave]

I'd tune it for max power ignoring the fact if what it has to interface into.

I'm a bit stupid that way.:banana:

Can you put a clutch on it to fan the revs up a bit?

[TZ350]

2 Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/kMhL8xbOLnk" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[pete376403]

Something like this?

[lohring]

Hey all! Bought a chainsaw today. wanted double the price if I would get one with 3hp instead of 2hp. started it and did not feel so fun, maybe I can fix it a bit (did I sketch on an exhaust) ... Are there any here who have fumbled with chainsaws? Also had carburetor lying around. It's a 35cc.

We modified a 35 cc race engine to give almost 12 hp. We changed to a high rpm pipe and lost 2 hp but could run the engine to its mechanical limit around 23,000 rpm. See https://www.modelgasboats.com/magazine/tech-articles-mainmenu-608/244-cmb-35-record-engine for the details of our testing and modifications.

Lohring Miller

[Muhr]

The stuff is not the most robust on the market so it will not be any 15000k, but what can you expect for 300 €. Exhaust, I think it should get at least. Was out and used it today and it is quite weak. Disassembled it when I was done outdoors. The port geometry and engine design are almost made to be able to adjust (or not) ..:rolleyes:
If I manage to squeeze out 3-4 hp, I am more than happy

[jonny quest]

The stuff is not the most robust on the market so it will not be any 15000k, but what can you expect for 300 €. Exhaust, I think it should get at least. Was out and used it today and it is quite weak. Disassembled it when I was done outdoors. The port geometry and engine design are almost made to be able to adjust (or not) ..:rolleyes:
If I manage to squeeze out 3-4 hp, I am more than happy

Tighten up squish and raise compression, raise ports back up to where they were, a little more intake area... and that's it.

A full expansion chamber you'll need to rev it more, and I don't think you'll have as widen of a powerband without a lot of pipe development. The stock cans on engines like this are really good for the powerband they need to run in.

[jonny quest]

I thought you could base mill cylinder to tighten up squish and compression, just looked and that's part of case too.

Best bet is make a longer rod.

[lohring]

I thought you could base mill cylinder to tighten up squish and compression, just looked and that's part of case too.

Best bet is make a longer rod.

What do the transfer passages and head look like. It might be easier to increase the stroke to tighten the squish if there is a squish area. Otherwise the pipe with high enough exhaust port timing will be the easiest. Rpm equals easy power. The limit will be crankshaft flex and the big end bearing. it looks like the crankshaft isn't an overhung design, so that should hold up.

Lohring Miller

[Muhr]

Thanks guys for the suggestions!
The problem i se with an engine like this, which relies on crankcase compression the more port time the less compression. Together with the fact that it has a piston-controlled intake, it makes a bit of a Catch 22 without a proper exhaust.
It has both a traditional piston-controlled intake port and a port through grooves in the piston to the transfer ports (which I have never seen before, perhaps common in these applications)
I tried porting a bit and I can not say that I noticed any big difference. It is 1 mm in squish so you could do a little there, but it is not a quick fix to stroke it or make a new connecting rod ...

[lohring]

My articles on what we do to our industrial 26 to 30 cc piston port, race engines are here:

http://namba.com/content/library/propwash/2015/October/#6
http://namba.com/content/library/propwash/2016/April/#5/

Lohring Miller

[SwePatrick]

, but it is not a quick fix to stroke it or make a new connecting rod ...

Make new lower plate that holds the crank, offsetbore the mainbearings to alter to desired squish.

[husaberg]

Get rid of crap cylinder replace with noncrap one.
later on, realise i should have just brought a bigger saw.
Divorce wife get a younger girlfriend and central heating.
give saw to wife in the settlement.

[Pursang]

https://i.gifer.com/g39h.gif

[TZ350]

.
I just love that chain saw.

<iframe width="560" height="315" src="https://www.youtube.com/embed/57oejQbyJR0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

2Stroke Stuffing. Includes a brief run with the 24/7 on the dyno. Sounds much better with the longer inlet tract. Progress.

[Joshua_]

Kia ora,

I am wonder where I should go to read up on some modern 2T theory. I have read the performance tuning graham bell & tuners handbook but they seem mighty old - one suggested I buy a fancy scientific calculator.
I've been following Alex on 2T stuffing youtube channel for years.

[Frits Overmars]

Kia ora,
I am wonder where I should go to read up on some modern 2T theory.Kia ora to you too, Joshua.
HERE would be a good start.
I can also recommend http://www.pit-lane.biz/t117p246-gp125-caracteristiques-aprilia-rsa. It's a French forum, but the Aprilia-thread is largely English-spoken (Maori not so much, yet)

[lohring]

I've written many articles on high performance two strokes, especially for our small racing two strokes. One series is below:

Lohring Miller
PS The links in these articles don't work any more.

349459
349456
349457
349458

[Joshua_]

I've written many articles on high performance two strokes, especially for our small racing two strokes. One series is below:

Lohring Miller
PS The links in these articles don't work any more.

349459
349456
349457
349458


Thank you very much - I'll read over these today :> I really appreciate the help. I accidentally asked the same question in a facebook group called moped army. I had seen a heap of cool projects on there but no one seemed to have much in depth theory going on. More bolt on go fast parts.

[TZ350]

Kia ora, I am wonder where I should go to read up on some modern 2T theory.

Kia ora Josh. Mostly stuff posted by Wobbly and Frits. Some Team ESE stuff.

General secret 2S tuning stuff:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page2000

Some of the SuzukiGP-NSR110 info:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1680

A whole lot more good stuff:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1850?p=1131071959#post1131071959

110cc Crank Shaft half way down the page:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1750?p=1131050937#post1131050937

Making a decent ignition from a Chinese aftermarket thing:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1681?p=1131033289#post1131033289

[lohring]

A lot of what I know that I summarized in those articles was stolen from Frits and Wayne (wobbly).

Lohring Miller

[Frits Overmars]

A lot of what I know that I summarized in those articles was stolen from Frits and Wayne (wobbly).We all have the same goal here: promoting two-strokes. So spread the word Lohring; the more the merrier.

[ken seeber]

Isn’t life so interesting. A couple of centuries ago when I was a kid, having twin carbies on your old pommy Morris or Prefect, you were hot.

Well nothing has changed. Yep, I’m hot. Moving onto twin carbies for the DCI engine, or even triple if you count the original.

Finally got them and made up some adapter blocks and some fiddly throttle shaft arms and connected these to a cable splitter. Good to know is that the Chinese supplier has pre-set the jet screws to the correct DCI requirements. No worries there.

In between times, made a shitty vid of some action. https://www.youtube.com/watch?v=iAf1gbWztT8

The DCI passage does in fact communicate with the cylinder in two ways:

1. Direct to the upper cylinder, with, in this case, the same duration as the original transfers and the existing B ports with a duration of around 120 degs.

2. Connecting to the crankcase when the piston is near TDC. This was unavoidable with a standard piston with the usual side cutaway that exposes the transfer port to the crankcase. In this case the duration of the DCI connection to the crankcase is a mild 114 deg, compared to the original piston port inlet duration of 160 deg.

Some possible subtle interactions going on, but there you go. Maybe do a piston with filled in sides to prevent the crankcase communication.

Anyways for now, give the two carbs a try.

More to come.

349466

[Frits Overmars]

...Moving onto twin carbies for the DCI engine, or even triple if you count the original.
The DCI passage does in fact communicate with the cylinder in two ways:

1. Direct to the upper cylinder, with, in this case, the same duration as the original transfers and the existing B ports with a duration of around 120 degs.

2. Connecting to the crankcase when the piston is near TDC. This was unavoidable with a standard piston with the usual side cutaway that exposes the transfer port to the crankcase. In this case the duration of the DCI connection to the crankcase is a mild 114 deg, compared to the original piston port inlet duration of 160 deg.

Some possible subtle interactions going on, but there you go. Maybe do a piston with filled in sides to prevent the crankcase communication.What's wrong with crankcase communication Ken ? You'll need it anyway, you wouldn't have to find a special piston (although that wouldn't be too hard in your position) and you could omit the original carburetor. KISS, you know?

Come to think of it, a fully closed piston skirt might be helpful in establishing whether opening the DCI carbs increases the revs due to the increased transfer time.area or due to the increased intake time.area, or both.

[jonny quest]

KTM puts the injectors in the throttle body on their factory race bikes. Apparently they're leaving the TPI in place to give the impression that they are still running them.

[lodgernz]

I should know the answer tothis:
My 2T goes noticeably better out of corners on a cold race day than a warm one. What does that say about my carb settings?

[diesel pig]

I should know the answer tothis:
My 2T goes noticeably better out of corners on a cold race day than a warm one. What does that say about my carb settings?

Your mid range carburate setting is a bit lean? I may be wrong I have been before.

[Frits Overmars]

My 2T goes noticeably better out of corners on a cold race day than a warm one. What does that say about my carb settings?Not much. A two-stroke with perfect carburation for cold circumstances will produce more power in those cold circumstances than a two-stroke with perfect carburation for warm circumstances will produce in those warm circumstances. Yes, two-strokes like cold air.

Cold air is denser than hot air; even if the mixture is too rich for cold air, the engine will burn a larger percentage of this fuel and thus produce more power in cold circumstances.
In your case the mixture can be too rich for cold air, perfect for cold air, or too lean for cold air but still too rich for hot air. In any of those cases cold power will be higher than hot power.
Only when the mixture is too lean even for hot air, the differences between cold power and hot power will disappear (and your engine will notify you by refusing to start when cold).

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/lwak84q9Ag4" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

2Stroke Stuffing. A bit of CNC action in this one. The supercharged engine is taking shape.

[TZ350]

.

349473349471349472
My original issue was, that when I shut the throttle after a hard run in top gear with fixed ignition and WOT. The engine picked up for a bit after I partly closed the throttle. I was able to replicate it on the dyno. WOT = Blue line, partly closed = Red line. The consensus seemed to be that the fuel curve went rich at WOT and needs straightening and the ignition retarding at peak RPM to enjoy the benefits of some over rev power.

I have modified the carb for replaceable air correction jets. And have wired in an Ignitec ignition. Ignitec's are available here in New Zealand from "Fast Bike Gear" in Auckland.

I have a DCCDIP1-Race version. https://www.ignitech.cz/en/vyrobky/dccdip1_race/dccdip1_race.htm

The great thing about these DCCDI units is that they generate their own CDI spark from 12Volts. So they can be powered by a 12-14 or 18Volt battery. Mine draws only mA's when idling and about 1.25A at full RPM.

My version can also be powered direct from the bikes AC generator.

349474

The Ignitec I have has a mapping option to pulse a solenoid power jet, PWM at 10Hz. So I got one of these little air solenoids, hopefully it can handle fuel without melting. The plan is to use it as a power jet to richen up the mid range and lean off the over rev.

I have finished the wiring and got the bike running ready for fiddling with on the dyno. Just in time for New Zealand to be plunged into "Lock Down". The Govt went hard and early, hopefully we can beat the virus again and get back to enjoying our freedom soon and the relativly good economy we have.

Anyway I am now confined at home and will have to wait a week or three before I can get back to work to work on the bike.

[lodgernz]

Not much. A two-stroke with perfect carburation for cold circumstances will produce more power in those cold circumstances than a two-stroke with perfect carburation for warm circumstances will produce in those warm circumstances. Yes, two-strokes like cold air.

Cold air is denser than hot air; even it the mixture is too rich for cold air, the engine will burn a larger percentage of this fuel and thus produce more power in cold circumstances.
In your case the mixture can be too rich for cold air, perfect for cold air, or too lean for cold air but still too rich for hot air. In any of those cases cold power will be higher than hot power.
Only when the mixture is too lean even for hot air, the differences between cold power and hot power will disappear (and your engine will notify you by refusing to start when cold).

Thank you Frits.
So basically, the higher you go the fewer, and the rest of the other the same, as my mother used to say.

[ken seeber]

All plumbed up and ready to go. Made up a blanking plate (good idea Frits) for the original inlet for when that carb is removed for part of the initial trials. Included a phallus, attached to the inside of the plate, to fill up most of the inlet passage volume..

[ken seeber]

The pics:

349495349496349497349498

[TZ350]

2Stroke Stuffing

<iframe width="560" height="315" src="https://www.youtube.com/embed/rMAN2lQ4RcM" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

First Start. As Dr. Frankenstein said to Igor, "IT'S ALIVE".

[HalfStrokes]

2Stroke Stuffing


This would be my favourite watch on Youtube, this guy and what he has tried and thinks about has to have 2stroke oil for blood.

[TZ350]

KTM puts the injectors in the throttle body on their factory race bikes.

If you can find a photo or two I would love to see them as I am very much interested in 2S EFI.

[husaberg]

If you can find a photo or two I would love to see them as I am very much interested in 2S EFI.

You just look in Neils pics form a few years ago if you wannt to see what KTM will do next:msn-wink:

[Peter1962]

If you can find a photo or two I would love to see them as I am very much interested in 2S EFI.


On ktmtalk.com there is a huuuuge thread on this subject, lots of controversy also.
https://ktmtalk.com/showthread.php?560509-2022-New-Fuel-Injection-System/page46
The opinion of Jeb, the administrator (see posting nr 434) :


Extremely unlikely. KTM has said TBI is too dirty to meet Euro4 specs, and it's doubtful they will make a Euro only version bike. If they were going to do that, they could have just stayed with carbs for the non-Euro bikes to begin with. But then you'd have massive threads like this one pining away for TPI.

For the folks that are reading this thread and thinking that TPI is junk, please know that the vast, vast majority of TPI owners never do these kinds of mods and are perfectly happy with the way the bike runs. I know one guy personally that tried the GET on his TPI and removed it after a few months. Every other TPI owner I know has left them stock. It's nice there are options for folks that love to tinker or are unhappy with TPI, just as there were in the carbed days. These forums tend to concentrate that kind of thing and make it seem like everyone is doing these mods, when in reality, very few are.

I agree with him, TPI is here to stay.

[Flettner]

I was on KTM talk for a while, started a twostroke injection thread to discus TPI and other injection methods, pros and cons, I got savaged. So I keep my opinion to myself, Ill let there 'intellectuals' fight it out amongst themselves. I might add, experts who had done nothing themselves.

[TZ350]

2012, YZ250. Took KTM a while but they eventually caught up:msn-wink:

Flettner was running TPI before KTM. Basically KTM dismissed Flettner's experienced input and they pursued other more complex EFI ideas that ultimately did not work. Before trying to copy and then patient for themselves Flettner's TPI system. KTM's patent application failed because it was Flettner's original idea and he had proven its viability.

349563349564 .... KTM's progression of development.

349565 ..... Flettner's TPI system, maybe about 2 years before KTM's.

[Flettner]

Tried to patent it for themselves.
TM stopped them, prior knowledge.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/zRq7I9HuqLw" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Turbo small bore 2stroke.

<iframe width="560" height="315" src="https://www.youtube.com/embed/5Hbhvq3nldY" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Fun with 2strokes does not have to be expensive. 8's on a mini bike!!! I think that would be faster than the Kawasaki 500 triple I had.

[Peter1962]

Tried to patent it for themselves.
TM stopped them, prior knowledge.

Neil, do you happen to know if Fabio from PowerCDI is still working on the project to make a specific version for the TPI ?
And also a question more oriented to yourself : has the MK2 version of TPI shown progress ? What about comparing it to TPI 'classic' ?

[TZ350]

.
349545

I wanted to refine my EFI Pseudo MAP program and have been spending some of my time in CV19 lockdown developing an Arduino Nano setup to simulate the crankcase pressure wave I recorded from bike.

Common MAP pressure sensors display their reading in discreet 1ms output's not as a continuous analog line. I needed to simulate this so that I can then use the simulated 1ms output to develop and test the new crankcase pressure reading Pseudo MAP program.

349547

This is the reading I recorded from the crankcase pressure sensor on my bike at 4k RPM. The yellow dot is the ignition trigger and the highest crankcase pressure is at BDC, the lowest at TDC. The idea is that changes in mass air flow through the motor can be determined by changes in the Delta between highest/lowest pressures.

349546

This is the simulation program at 4k RPM. The simulation sweeps from 1k RPM to 13k RPM and at 12k there is only five 1ms pressure readings.

The aim is to use this simulator so I can refine my Pseudo MAP program without having to run the bike.

[TZ350]

.
349566349567349568

Actual crankcase MAP sensor readings at idle 1.8k rpm, and 4k rpm and 10k rpm.

MAP sensor, Blue line. 500mV a division. 0-5V = 0-2.5 bar MAP sensor. The MAP sensor has a 1ms settling time which is common for these types of sensor.

Interestingly, at idle the crankcase pressure rapidly drops at TPO transfer port opening but at higher rpm and load this is not happening.

[Flettner]

Neil, do you happen to know if Fabio from PowerCDI is still working on the project to make a specific version for the TPI ?
And also a question more oriented to yourself : has the MK2 version of TPI shown progress ? What about comparing it to TPI 'classic' ?

Ive not heard from Fabio for some time. At one point he was not very well.

Mk2? Work gets done on it when time and money are available, slow lately. Although this latest lockdown has meant some progress. Apart from finishing an air filter system its ready for some track time somewhere.

[jonny quest]

I can't seem to find picture now.

There was a picture of the team bike where the throttle body was just hanging there, clearly showing 2 injectors mounted to bottom of TB. The stock TPI injectors are still in place, but apparently have a dummy hose connecting the two together.

The TPI I believe currently works decent for a few reasons. "A" port doesn't receive the bulk of fuel, less short circuiting. Downward position in B helps with mixture motion.

TPI for 50% and under, TBI FOR 50% and over may be the best power solution. 4 injectors for each cylinder

[Flettner]

I can't seem to find picture now.

There was a picture of the team bike where the throttle body was just hanging there, clearly showing 2 injectors mounted to bottom of TB. The stock TPI injectors are still in place, but apparently have a dummy hose connecting the two together.

The TPI I believe currently works decent for a few reasons. "A" port doesn't receive the bulk of fuel, less short circuiting. Downward position in B helps with mixture motion.

TPI for 50% and under, TBI FOR 50% and over may be the best power solution. 4 injectors for each cylinder

DI also run TBI to assist with high speed operation, perhaps thats what KTM are trying.
Im all in for four injectors but in the A and B ports. Blend the A injectors in, as appropriate, when gas inertia warrants it. Way more accurite fueling and easier to impliment 'skip cycle' injection traction control. True traction control not just shitty retarding the ignition. Way more likely to waste unburt fuel out the exhaust with only TBI.

[Peter1962]

I can't seem to find picture now.

There was a picture of the team bike where the throttle body was just hanging there, clearly showing 2 injectors mounted to bottom of TB. The stock TPI injectors are still in place, but apparently have a dummy hose connecting the two together.

The TPI I believe currently works decent for a few reasons. "A" port doesn't receive the bulk of fuel, less short circuiting. Downward position in B helps with mixture motion.

TPI for 50% and under, TBI FOR 50% and over may be the best power solution. 4 injectors for each cylinder


The MK2 idea of Neil seems more logic : combine the existing TPI with two aditional TPI injectors, activated at a certain RPM. Why combine it with TBI in the first place ?

[Flettner]

The MK2 idea of Neil seems more logic : combine the existing TPI with two aditional TPI injectors, activated at a certain RPM. Why combine it with TBI in the first place ?

To me Mk2 TPI makes sense but Im no motorcyle manufacturer. Im looking further ahead with this skip cycle, I guess they are concerned with charge cooling into the crankcase and perhaps better oil transmission to the bigend. I believe Ive sorted the bigend oiling / bearing cooling issue and heavily water cooled crankcase.

[peewee]

I was on KTM talk for a while, started a twostroke injection thread to discus TPI and other injection methods, pros and cons, I got savaged. So I keep my opinion to myself, Ill let there 'intellectuals' fight it out amongst themselves. I might add, experts who had done nothing themselves.

they dont have a frits or jan or wobbly so what could a person even learn there :weird:

[Flettner]

Fu$%king rubbish carburetors, who needs them.

[Peter1962]

Fu$%king rubbish carburetors, who needs them.

What we need is a MK2 kit, for the ktm-husqvarna-gasgas 250 and 300 TPI's. That is where the two stroke market is. They sell more than 50.000 of those TPI's per year. In fact, the KTM group is selling more 2 strokes then 4 strokes, not counting the 50cc mopeds.

In the hard-Enduro world championship, more than 50 % of the field are ktm-husky or gas-gas two strokes.

There are now a couple of firms who do a 'refllash' of the existing TPI chip, but that is not real evolution...

[ken seeber]

Below is a consolidated update on the DCI project. Taken a while, but lots of other stuff going on.

Like all good things, there is a happy ending.

Was pointed out that you need to pause on the various text cards to fully read them.


https://youtu.be/ae8qOvGoWgM

[jonny quest]

That is really cool Ken!

I'll re watch video when I have more time... but

Ultimate goal is heating air to expand.

Why do you think it seemed to rev quicker and higher with such a small carb via DCI? How is it getting enough VE through such a small hole compared to standard carb arrangement?

Are we wasting that much airflow through tunnels? Are we creating too much VE under piston to cause pumping losses?

[Flettner]

Below is a consolidated update on the DCI project. Taken a while, but lots of other stuff going on.

Like all good things, there is a happy ending.

Was pointed out that you need to pause on the various text cards to fully read them.


https://youtu.be/ae8qOvGoWgM

There is so much to still to be learnt, 'Ken the doer'. This is real intetesting. Keen to see the next step.
Might be interesting with a form of TPI.

[Flettner]

https://youtu.be/av-pdf2Gt5g

[Muhr]

.
349566349567349568

Actual crankcase MAP sensor readings at idle 1.8k rpm, and 4k rpm and 10k rpm.

MAP sensor, Blue line. 500mV a division. 0-5V = 0-2.5 bar MAP sensor. The MAP sensor has a 1ms settling time which is common for these types of sensor.

Interestingly, at idle the crankcase pressure rapidly drops at TPO transfer port opening but at higher rpm and load this is not happening.

interesting reading

https://www.diva-portal.org/smash/get/diva2:962216/FULLTEXT01.pdf

[Frits Overmars]

interesting reading
https://www.diva-portal.org/smash/get/diva2:962216/FULLTEXT01.pdfIt certainly is. Thanks Muhr :niceone:

[philou]

I cannot find the messages concerning the injection on the aprilia 250.

according to a certain Francesco who would have worked on it. It worked very well with 2 podiums.

with only one injector per cylinder, that seems weak.

[Frits Overmars]

I cannot find the messages concerning the injection on the aprilia 250.
according to a certain Francesco who would have worked on it. It worked very well with 2 podiums.
with only one injector per cylinder, that seems weak.To the best of my knowledge no fuel-injected Aprilia 250 ever achieved a podium finishing, or any finishing for that matter. And unless I'm very mistaken, the picture in the left shows an Aprilia-500, not a 250. The RSW500 had four injectors: two in the throttle bodies and two in the crankcases. So I suppose your Francesco may have some explaining to do...

[philou]

I was wrong, he talks about the rsw 2 which is indeed the 500.

he maintains that there is only one injector. I do not believe it. one cannot be enough to feed properly

[TZ350]

.
349632

I would much prefer to work with fuel injection but for now my 50 has a 30mm carburetor. A bored out 24mm OKO.

349630349631

I hesitate to call my modification a pulsed power jet. But here is my attempt at a fuel enrichment device that can be PWM. The Ignitec ignition allows for mapping the pulse width against rpm. So if it works I can enrichen the fuel curve at peak torque and lean it off for over rev.

349633

I am using a small air solenoid. Here is hoping that the fuel does not melt the seal and plastic parts.

[jamathi]

To the best of my knowledge no fuel-injected Aprilia 250 ever achieved a podium finishing, or any finishing for that matter. And unless I'm very mistaken, the picture in the left shows an Aprilia-500, not a 250. The RSW500 had four injectors: two in the throttle bodies and two in the crankcases. So I suppose your Fransesco may have some explaining to do...

It was unrideable, so they went back to carburetors...
No 250 Aprilia was ever raced with injection!
Injection was tried on the dyno, on the 125 engine, with no positive results...

[JanBros]

.
for now my 50 has a 30mm carburetor. A bored out 24mm OKO.


so is there any venturi left at WOT ?

[Condyn]

Looking for some guidance in understanding the fundamentals of two stroke ignitions and their relationship to compression. I know its a vague request, however even after much reading I am still questioning whether an engine with say 11:1 compression would be happy with the same advance as its 15:1 counterpart.

[Frits Overmars]

Looking for some guidance in understanding the fundamentals of two stroke ignitions and their relationship to compression. I know its a vague request, however even after much reading I am still questioning whether an engine with say 11:1 compression would be happy with the same advance as its 15:1 counterpart.The seemingly simplest questions often require the most in-depth answers, Condyn. In today's two-strokes much depends on the exhaust pipe. A higher compression ratio before TDC means a higher expansion ratio after TDC; a greater part of the energy in the combustion gases is used in pushing the piston down. In itself this is fine, but it also means that less energy is left in those gases when they enter the exhaust pipe. And if that pipe is not fed with energy, it won't do anything useful in charging the cylinder for the next combustion cycle.
So a high compression ratio may give a stronger push on the piston, but the next cycles will suffer and the nett result depends on how efficient the pipe deals with the available energy.
Personally I am in favour of a low compression ratio for a competition two-stroke. A good pipe can triple the power of such an engine, as Jan Thiel has proven, so let's give that pipe something to work with.

Where does the ignition timing come in? The later you ignite, the later the combustion phase will be complete and the less expansion will take place between the end of combustion and exhaust port opening. So retarding the ignition is another way of transfering energy to the pipe.
An 11:1 compression ratio with early ignition may well behave just like a 15:1 compression ratio with late ignition, but once again it depends on the efficiency of the pipe.

If we were talking four-stroke, all would be clear. A poppet exhaust valve opens with an initial velocity of zero, so the initial exhaust pulse coming from a four-stroke is quite weak in comparison to a two-stroke pulse, where the exhaust port opens with an initial velocity of about 1,5 times the mean piston velocity, releasing a mighty big bang.
A four-stroke does not depend nearly as strong on pipe effects as a two-stroke does, so it needs all the compression ratio that can be built into it. But it will never be a match for an equal-capacity two-stroke.

[Condyn]

Dynamics, dynamics, dynamics. Thank you very much Frits. Makes perfect sense.
I might guess that a greater amount of energy translates to a greater amount of heat in this case? Maybe the pipe could be longer to accommodate a lower compression ratio or a later ignition. (Given the 2.4 million other variables stay the same)

[Frits Overmars]

Dynamics, dynamics, dynamics. Thank you very much Frits. Makes perfect sense.
I might guess that a greater amount of energy translates to a greater amount of heat in this case? Maybe the pipe could be longer to accommodate a lower compression ratio or a later ignition. (Given the 2.4 million other variables stay the same)Whilst writing my previous post I had considered including the correlation of ignition timing, exhaust gas temperature, speed of sound and pipe length, but I decided not to make things too complicated right away. But you are perfectly right Condyn: pipe length is an important factor when meddling with compression ratios and ignition timing.

[TZ350]

.
More adventures and two stroke fun at 2Stroke Stuffing:- https://youtu.be/7B64Nhldbe4

[TZ350]

.
now my 50 has a 30mm carburetor. A bored out 24mm OKO.



so is there any venturi left at WOT ?

I am suspicious you might be right and will be looking into it some more.

349636 Suzuki RG50. 30mm carb. WOT blue line, partially closed red line. Issue simulated on a DynoJet dyno.

I am not sure about that 30mm carb. The bike runs well enough but after a hard run down the straight it picks up speed if I close the throttle a bit. My first thought is that by the end of the straight it is running in the over rev area and the smaller throttle setting is leaning the mixture off and heating the pipe for a bit more rpm.

The carb has been fitted with replaceable jets for air correction. I have also replaced the straight line MX80 ignition with an Ignitec DCCDI programmable one and also made a PWM power jet thing.

You could be right about that 30, and what it really needs is a smaller carb. I have a spare 24mm to try too.

But I can't test anything until we are out of lock down. There is a major vaccination drive going on in the country and the city I live in is completely closed. The rest of the country less so as there is no sign of CV19 there.

[wobbly]

Many very fast 50cc Freetech etc use 30mm HV Lectron carbs , the trick here is that this particular carb , like its bigger brothers has a venturi radius behind the slide that is 4mm smaller than the nominal bore.
Thus at 1/2 throttle it operates like a 24 Dia , and if the flow bench tests are the same as the bigger versions , they flow more air at WOT than the equivelant bore sized Keihin/Mik/Dell.
Of interest as well is that the Lectron can be run up around 50* downdraft to straighten out the inlet duct without spewing fuel thru the pilot circuit under brakes , as all other carbs do except the
actual rare carbs designed with an angled bowl.

[JanBros]

Personally I am in favour of a low compression ratio for a competition two-stroke.

I know you probably do not like this kind of questions as their is no simple answer, but I'm gonna ask it anyway :
what would you consider low and is there some sort of correlation with BMEP ?

[Frits Overmars]

More adventures and two stroke fun at 2Stroke Stuffing:- https://youtu.be/7B64Nhldbe4Alex' latest video prompted me to react and although I value the technical level of the Kiwibikers infinitely higher than the average Fakebook level, maybe I can avoid some mishap by posting it here as well.
Hei Alex, as you know I like the way you promote the two-stroke engine with your videos and I am well aware that you have thousands of followers. Not everyone of those will be as experienced as you are, and I noticed a 'dangerous ten seconds' from 06:52 to 07:02, where you set the piston position with a depth gauge and then tighten the ignition nut with an air wrench. Those unexperienced followers might follow your example and ruin the depth gauge because they never saw you removing it before tightening the nut...



I know you probably do not like this kind of questions as their is no simple answer, but I'm gonna ask it anyway :
what would you consider low and is there some sort of correlation with BMEP ?If I come across a question that I don't like, I can always pretend I didn't see it Jan. You learn these things on Fakebook, you know :msn-wink:.
What would I consider low? That is a question I never asked myself; I prefer numbers over expressions like low and high. But in order to try and answer your question let's say that a compression ratio lower than 10 is definitely low. And I am talking geometrical compression ratio, not the nonsensical Japanese 'trapped' compression ratio that is meaningless unless the exhaust timing is also mentioned (which it never is).

Of course there is a correlation with BMEP, although I cannot confirm that it is linear. I like these low compression ratios because I get more power with them, and since power comes from BMEP x rpm, and since the optimum rpm is pretty much defined by the angle.areas of an engine, which are not influenced by the compression ratio, the power must come from the BMEP.

To be absolutely precise, although the angle.areas of an engine are not influenced by its compression ratio, the specific angle.areas are because the volume that has to be scavenged, increases when the combustion volume is increased. So arithmetically the achievable rpm becomes smaller for a lower compression ratio. But this influence is negligible, as long as you do not go really low with your compression ratio, like 4:1 or so:nya:.

Am I joking? Now that I write it, I wonder why I never tried it; the exhaust pipe would love it! And I have nothing to lose; a 4:1 compression ratio can't possibly damage an engine, and replacing a head if it doesn't work is a matter of minutes.

One more thought to crank your brain:
After the piston has closed the transfer ports on his way up, the exhaust pipe tries to shove washed-through fresh mixture back into the cylinder before the exhaust port closes.
This shoved-back mixture raises the pressure in the cylinder and at some point this pressure has risen so high that the pipe is no longer able to shove back any more mixture.

Now if the volume above the exhaust port is bigger, there is more room for shoved-back mixture and the cylinder pressure will not rise quite so quickly.
The pipe can then cram more mixture into the cylinder before exhaust closure, which is good for power.
How can we make the volume above the exhaust port bigger? By fitting a head with a bigger combustion chamber volume....

[Condyn]

I have built 8 different pipe designs for a specific vintage air cooled engine, and think I have arrived on something usable. I was stuck on long headers (around 35%) for a few designs with the thought of delaying the diffusers action on the bad transfer geometry. The first pipe I built with a 33% header worked WAY better instantly. (Random tangent I know)

I think that I am sold on trying a lower compression ratio on my next engine with much efforts in making the pipe suit.
The compression ratio is currently 15:1. Being that it is air cooled I am gathering a lower ratio might be beneficial in more than one way.

This is an interesting perspective/logic Frits. I have always associated a high exhaust port with bad trapping and lower cylinder pressures, without thinking of the pipes roll.

Another thought I have is the extra spilling that my vintage engine likely has, and the effect that has on this theory. I have read and think I understand Neels literature on contact discontinuities. If an engine has a garbage trapping efficiency, a lower compression ratio with a larger area in the cylinder for the smeared up pipe to be pounded back into, it may wasted space?

My thought process is probably wacky.

[Vannik]

The pipe can then cram more mixture into the cylinder before exhaust closure, which is good for power.
How can we make the volume above the exhaust port bigger? By fitting a head with a bigger combustion chamber volume....

Or running a lower exhaust port.....

[Frank S.]

An 11:1 compression ratio with early ignition may well behave just like a 15:1 compression ratio with late ignition, but once again it depends on the efficiency of the pipe.


Hi Frits,
would the pipe in these two cases be of the same shape? Of course this depends on the exhaust gas temperature,
so the question is, what happens to the EGT by lowering the compression ratio?
I wonder what pipe a 4:1 cr requires?

Btw I am doing 50cc endurance racing (mainly a 8h race in Germany) and I am reading this threat (and on Pitlane) for some years now, but all the answers I had were already asked and answered. Thank you for sharing your knowlege. It is better than all the 2T books I have bought.:Punk:

[TZ350]

.
349639349640349641

Before I take anymore material out of the combustion chamber I am looking for some suggestions from people with more up to date experience with 2 strokes and methanol than my clumsy 1970's experience with Meth and RD's.

The engine is an air cooled 1971 Kawasaki F81M rotary valve 250 with a 70mm bore being prepped for post classic road racing.

Un corrected compression ratio is currently 15:1, squish 1mm. Fuel 25% Methanol, 5% Acetone, 70% 96 petrol. The plan is to keep adding Methanol until the cylinder head temperature hovers around 70deg C.

The question is, what is a sensible compression ratio and the sort of spark plug heat range to use with Meth.

[wobbly]

Wow , a sudden burst of interest over one small comment - but its a big can of tasty worms.
To jump in on the first question , yes there is a direct correlation between BMEP and static compression.
As BMEP rises so is the Delivery Ratio , and or Trapping / Scavenging Efficiency. These variables all ultimately increase the amount of clean A/F in the cylinder prior to EPC.
Thus as these effects become more efficient the dynamic compression increases , and the law of diminishing returns begins to affect the optimum static compression that can be used.

Then the next influence is fuel quality/octane and makeup.
A general approach is that leaded race gas is optimised by lots of com , minimal advance and very lean mixtures.
Unleaded /pump low octane fuel is the dead opposite - it hates com , likes advance and makes best power when on the richer side.
Thus the old Elf 130 was run up at 18.5:1 and was combined with minimal advance and around 700* + in the header ( not in the spigot like the Aprilia had )
The later GP bikes on FIA unleaded were fastest with a max of around 15:1 , way more advance and richer jetting , simply due to the fuels characteristics.
This approach lowered the pipes bulk average wall temps , and thus those designs changed to suit.

Low com does increase the available cylinder volume above EPC , and does lower the compressing losses BTDC , but these elements pale into insignificance compared to the detonation resistace
that is set by the compound effect of the com and the extra advance this lower com number will allow.
Programmable ignitions make finding the optimum advance relatively easy on the dyno , but then finding the best power com involves the nighmare of making a bunch of inserts with nothing changed
but the cc , and then having to reconfigure the ignition for each change.

But sadly even in the case of changing from 12:1 to 16:1 there will be a huge difference in chamber geometry - and thats another can of worms as well.
Nothing is easy when operating on the outer limits.

Edit - the other question was related to the effect on EGT by dropping com - in this case EGT will rise as more of the finite energy within the trapped fuel is released into the header instead of heating the piston/water.
But this is directly offset the other way by adding timing , so its an endless circular function trying to find the best combination.

[wobbly]

TeeZee , having done tons of work using Meth before I had grey hair , I wonder mainly why you are using Meth as an aditive to petrol.
By far the best results for an aircooled is to maximise the natural cooling effect of huge amounts of rich Meth mixture going thru the engine.
Using 90% Meth , 5% Acetone , 5% petrol means you can run identical com to Avgas as you would in a watercooled cylinder , and have no heat soak related power loss.
The effective octane of this mixture is around 130 , but you must have a cold ( 11 ) plug and as much grunt as you can get with the ignition if running +20% rich with high com.
Nowdays this is easy , run the ignitech at 14.2 charging volts and parallel up the outputs of a DC CDI P2.
I used a huge Crane ignition coil designed for CDI use in NASCAR race engines as it has the only two things that will increase spark energy in a DC CDI , very low primary resistance and high inductive reactance.
Ive got one if you want to give it a shot.
This setup pulled nearly 5 Amps from a P2 that previously ran at around 1.5A on a normal single coil - a massive increase in ionisation and burn time energy.
Do it right and 16:1 is a walk in the park for your application.

[JanBros]

TeeZee , having done tons of work using Meth before I had grey hair , I wonder mainly why you are using Meth as an aditive to petrol.
By far the best results for an aircooled is to maximise the natural cooling effect of huge amounts of rich Meth mixture going thru the engine.


because the bike is used in endurance racing and he does not want to pit every 15 minutes for refueling ?

[F5 Dave]

Nah we dont do much endurance over here, and Rob isn't getting any younger for that sort of malarkey. None of us are.

[jonny quest]

When the RSA went to unleaded fuel I understand after engine was adjusted for this fuel peak HP went up slightly.

What happened to lower rev range? Do it suffer slightly compared to the high compression leaded engine?

[Frits Overmars]

The RSA never went to unleaded fuel Jonny. Grand Prix Motorcycle Racing went to unleaded fuel long before the RSA was born.
Let's talk Aprilia RSW then. These ran a 19,5:1 compression ratio on 130 octane leaded fuel. When the stuff was banned, they initially ran a 14:1 compression ratio on unleaded, which made the engine lose bottom power but at the same time let it rev more freely to the pleasure of the riders. Then the compression ratio was gradually restored to 15,5:1. At the same time other paths of development were explored, so after a while the unleaded power was better than the leaded power had ever been.

[TZ350]

TeeZee , having done tons of work using Meth before I had grey hair , I wonder mainly why you are using Meth as an aditive to petrol. By far the best results for an air cooled is to maximize the natural cooling effect of huge amounts of rich Meth mixture going thru the engine. Using 90% Meth , 5% Acetone , 5% petrol means you can run identical com to Avgas as you would in a water cooled cylinder , and have no heat soak related power loss.

Thanks for your reply. When I first ran 100% meth the engine ran to cold to evaporate the fuel properly for good air/fuel mixture. It was so cold and leaner the more meth I pored in. Wound up so rich raw fuel was dribbling out the stingers. Bore wear from the bore wash was dreadful too. Ran warmer and better with 50/50 mix of meth and acetone.

The current approach of starting with 25% meth is to more scientifically with trial and error keep adding meth until I get the balance right between engine temp and heat soak. The bike will also have a head temperature sensor that adds fuel when the engine gets above a pre determined level. Again trial and error.


... but you must have a cold ( 11 ) plug and as much grunt as you can get with the ignition if running +20% rich with high com. Now days this is easy , run the ignitech at 14.2 charging volts and parallel up the outputs of a DC CDI P2.

I was unsure about this part, hotter or cold plug with a cold meth setup. Thanks for confirming the plug heat range. I have a good handful of NGK 9's and 10's but no 11's or 12's and they are expensive and harder to get.

I have one new really cold surface discharge plug. They are more available than 11's and 12's. Before I get any more, would surface discharge be Ok?


... Now days this is easy , run the ignitech at 14.2 charging volts and parallel up the outputs of a DC CDI P2.
I used a huge Crane ignition coil designed for CDI use in NASCAR race engines as it has the only two things that will increase spark energy in a DC CDI , very low primary resistance and high inductive reactance. This setup pulled nearly 5 Amps from a P2 that previously ran at around 1.5A on a normal single coil - a massive increase in ionisation and burn time energy. Do it right and 16:1 is a walk in the park for your application.

Thanks for confirming the com ratio possible. my 15:1 should be good. Interesting about the DC CDI P2 and the Crane coil. I was planning on using a P1 I brought from FastBike gear. I guess I will be getting a P2. Unfortunately they use different looms so it is a re wiring job now too. And I will have to re jig the charging system so that the voltage rectifier/regulator with capacitor holds output at 14.2 Volts at 5 Amps.

If I am going to run a P2 I was wondering about using one of those old twin plug heads. You know the kind that were popular in the 70's so that the off road boys could have a hot and cold plug and burn holes in their pistons. Because they did not understand that a hot plug was hot regardless if it was the one sparking or not.

Would a Hemi chamber, squish and firing two plugs be worth while power wise?

Wob. Thanks for your help and encouragement.

[wobbly]

I ran 90/5/5 for years in the MX only 125 National ( water cooled TM/Husky ) class karts , with many National titles and lap records.
Never had any issues with it being too cold or over fueling out the stinger - it ran 19:1 with a normal race petrol ignition curve , and the carb was jetted calculating 2.2 X the area of petrol
1 - pilot jet , 2 - std needle parrallel with drilled tube , 3 - drilled tube/ needle end annulus thinned at WOT and 4 - main jet area , split into 3/4 area of jet + 1/4 area of screw adjustable PJ.
This ran best at 800*C and no more than 1/8 turn on the PJ was ever needed to keep it there on the fly - but the pipe was very much shorter.
Running the Mega ignition setup a surface gap would be great - always wanted to but never tried that.
A cold plug is needed running the super high com setup as I believe the actual burn temp in the chamber is super high , even thou a ton of fuel is dumped into the pipe.
Using a 10 plug the exposed body would over heat causing pre ignition and holes in the piston.
I have tried a twin plug setup in a CR250 - made no difference at all - the chamber shape in a 2T is damn near perfect in any form for max flame front propogation.
Will send coil asap if needed.

[speedpro]

If you suspect problems with over-cooling could you shroud the engine and limit air flow to the fins?

[Grumph]

i've quoted it here before - but the only experience I've had with a surface gap plug could at least have been worse.
Stinking hot day at Ruapuna - over 30C - and my Mach 3 ran on when I came into the pits.
Under stress the plating on the plug faces had lifted and the slivers of plating became a glow plug.

If i used one in extreme circumstances as you propose, i'd take a light cut off the faces in the lathe before use. It's only a cosmetic layer.

[TZ350]

... ran best at 800*C and no more than 1/8 turn on the PJ was ever needed to keep it there on the fly - but the pipe was very much shorter.

I understand the need for a shorter pipe when running meth. But 800*C ? is that 800*C in the pipe EGT or was that meant to be 80*C ECT engine coolant temperature?.

[wobbly]

Sorry TeeZee that was a typo , should have been 800*F EGT in the header.
The engine on petrol was 1260 * F and was hard to keep at 120* F water temp , but on Meth it ran at 100 all day.

[jonny quest]

Latest generation Honda CR125. Right side crank seal pops out randomly.

Cases are in good shape, I've tried using 3m bond 1211. Didn't help. I know my piston ring is ready for a change, but it's not horrible... could that be the cause?

Suggestions for a bonding agent? I really don't want to use a punch and peen cases.

[Larry Wiechman]

Latest generation Honda CR125. Right side crank seal pops out randomly.

Suggestions for a bonding agent? I really don't want to use a punch and peen cases.

Three #6-32 Button Head Socket Cap Screws arranged in a bolt circle pattern that positions the heads to overhang the seal bore diameter.

[TZ350]

Sorry TeeZee that was a typo , should have been 800*F EGT in the header.
The engine on petrol was 1260 * F and was hard to keep at 120* F water temp , but on Meth it ran at 100 all day.

Great, thanks. I was wondering about ECT and EGT.

So I could get my head around the values I did some conversions to *C.

800*F EGT = 427*C
1260F EGT = 682*C
120*F ECT = 49 *C
100*F ECT = 38 *C

Thanks again, now I know what I am looking for.

[jamathi]

The RSA never went to unleaded fuel Jonny. Grand Prix Motorcycle Racing went to unleaded fuel long before the RSA was born.
Let's talk Aprilia RSW then. These ran a 19,5:1 compression ratio on 130 octane leaded fuel. When the stuff was banned, they initially ran a 14:1 compression ratio on unleaded, which made the engine lose bottom power but at the same time let it rev more freely to the pleasure of the riders. Then the compression ratio was gradually restored to 15,5:1. At the same time other paths of development were explored, so after a while the unleaded power was better than the leaded power had ever been.

The 'unleaded' power was better than the 'leaded' within 3 month's, mainly because a much better combustion chamber was used. There was no power loss at low rpm, and much better overrev... And spark plugs no longer cracked...

[jonny quest]

Was a lower compression head tried with leaded fuel?

Or, because "thermodynamics " says 18:1 is best... let's build everything around that and not make it a variable

[wobbly]

Simple really - the engine made best power at 19: 1 , at 18:1 it never made more even with added advance.
There is always a narrow window of variables that work in synergy with the fuel characteristics , and everything is arranged to extract the max power without detonation causing the need to compromise
egt or advance just to control this issue.
Its also amazing as Jan alluded to , is that the chamber shape shows big changes in performance with samll changes in geometry.

[sniemisto]

14mm stinger is very small.
For a 50 cc I never go below 16 mm

I'm back on this Derbi project. I haven't fixed yet the issue with low EGT on dyno. I got 10ml burette for compression volume measurement, I'm going to measure it soon.
We had race last weekend and I was forced to deal with exhaust and stinger first, as I had EngMod developed pipe plans to make more power. Other pipe dimensions changed at same time, so its not pure stinger diameter comparison. My last pipe had 14mm venturi and this new is straight 15,9mm without venturi.

I got good drop on EGT, it went down to 630*C on long wot run, as it was 670-680*C with smaller stinger. I was able to jet down main from 128 to 120 and ended up with 670*C. Bike was nice to ride with wide power and it was able to go on higher gearing that it used to before.

349652

Next I will proceed with compression ratios.

[F5 Dave]

That's a lot of revs for not very much power. Geez I wish I'd chanced over 13500 over rev. Just my old engine would destroy much after 12000, so I was conservative

[sniemisto]

Dave, you are right. I’m not happy with power level and it seem that max power is not going higher with current transfer and exhaust port design.
Our dyno hasn’t been calibrated against any other dyno, just with with weight dropping 5 meters and pulling roller to acceleration with rope wrapped around circumference.
It seems to be pessimistic against competitor bikes that have been measured in commercial dynos.
It leaves 14rwhp bikes behind on track.
This is only speculation of course, bike needs to be measured in commercial dyno to really know the power level.

There is also some effect from fact that EGT doesn’t go high enough in dyno. One plan is to use disc brake from car and run bike shortly against it to rise EGT. Then release brake and do the run.?

I think that tuning issues with current cylinder are:

-Auxiliary exhaust ports have timing (191) too close to main (192).
-Too big exhaust passage, passage to window ratio 96%
Too long transfer duration, 131.
Tranfers doesn’t have enough axial angle (8, 6, 59).
B-transfers not wide enough, there is big space between B and C.

I need to redesign these now as my EngMod model starts to be ok

[philou]

which cylinder do you use ?

[sniemisto]

It is modified Athena power valve 50cc. I also have one untouched new one in the box waiting.

[F5 Dave]

And as I awake a little more sober, I have to apologise for my post, that was out of line to criticise so I am sorry.

[wobbly]

Dave , you may have been pissed but you were right - never happens with me sadly.
Snie , the inertia measurement system with wound string and drropping weight is a good one , but the slow drum speed makes friction a bigger component.
You need to do a run down test to fix this.

14,500 is not alot of revs though , with good components its not stressing anything at all.
But yes , most of the specs you have revealed so far tell straight away what is wrong, as does the steep drop off after peak power.
The Ex/Aux split is way too small and the timings way , way low. Especially with not very wide transfers up at 131 , the Blowdown must be badly compromised.

As its a power valve cylinder you should be running reverse stagger as well like the Aprilia - as this scavenging system dramatically helps peak and overev power ,and the PV gives back more in the mid than the transfers loose.
My guess would be to fix the wierd axials ( why 59* - use Frits bore/stroke formula to get all the angles correct ) widen the B and then probably lift just the main Ex to get more split and correct the blowdown.
This also would go some way toward correcting the miles to big duct exit % as well .

The big stinger will be naturally helping mid power and will allow leaner jets to get the egt up , but I would go bigger and use a slip in tophat nozzle like I introduced in the TM R1 as this always makes better power.

Probably a bunch of other details way off the mark , but revealing the sim file is the only way to fix that.

[andreas]

I was assigned to care for a fleet of Suzuki rm 85's, and possibly tune a few of them; Anyone that has done any tuning on these? 04-19.

Also, I need better top end performance out of my yzf 1000r. I've read the yzf 750 cams are higher/longer and is a direct swap, but I'm poorly oriented with these engines. Same question: Anyone knows how to tune them, or where to look for information?

[Frits Overmars]

the inertia measurement system with wound string and dropping weight is a good one , but the slow drum speed makes friction a bigger component. You need to do a run down test to fix this.I don't think a coast-down run will be the solution just yet, Wob.
My dyno software has a calibration option that uses the dropping weight-system. The drum has to start rotating before the Hall-sensor receives its first pulse, so the stationary stick-friction is eliminated before the measurement starts. Then the drum has to perform two complete revolutions, wherein the time for each revolution is measured in microseconds, just like during a normal power run.
Then the weight is substituted with a different weight and the two-revolutions measurement is repeated, after which the software has sufficient information to calculate the inertia and the friction, assuming the friction is constant during these ultralow drum rpm values.

Once these values are known, we can perform a coast-down run. This is especially important if the dyno is equipped with an eddy current retarder. These retarders usually have cast-in cooling fins and their centrifugal ventilation function can absorb a consideral amount of power at high revs. The sum of friction and centrifugal pumping losses can be as high as 6 hp,
as I once measured by putting a turbo-bike on the dyno, accelerating it to 300 km/h and then lifting the rear wheel one centimeter off the drum. The coast-down time allowed us to put the kettle on and have several cuppas.
349660 349659

[TZ350]

Our dyno hasn’t been calibrated against any other dyno, just with with weight dropping 5 meters and pulling roller to acceleration with rope wrapped around circumference. It seems to be pessimistic against competitor bikes that have been measured in commercial dynos. It leaves 14rwhp bikes behind on track.
This is only speculation of course, bike needs to be measured in commercial dyno to really know the power level.

I have seen two well constructed home made dynos here. Both read lower than the Dynojet we use. We even did back to back tests between the home brew dyno's and the Dynojet.

The home brew dyno's calibration was checked in various ways. Calculation, Rope pull and run down. I cant remember the difference but it was significant, maybe 10-12% lower than the DynoJet. The conclusion from these results and after a bit of reading about other commercial dynos. Was that commercial dynos deliberately over read to flatter the customers ego. But it seems results between different DynoJets are consistent. And anyway, if you have a reliable dyno you can develop your bike whatever the real or imagined hp result may be. I suspect your dyno may be more "accurate" in real terms than our DynoJet.

[wobbly]

Right on TeeZee . When the DynoJet was being developed they were of course using a Harley and of course it made fuck all power.
Thus a fudge factor of 12% I believe was added right at the start so as not to piss off their largest customer base.

[F5 Dave]

When Chris set up the first dynojet, and first proper dyno business in lower north he started to get hardleys trickling in. I saw a few of the runs. There were some grumblings. But fortunately WMCC bought a dyno and that was producing the Real mens type numbers (at least 15% up on his) so he got no more Harley work after.

[husaberg]

Internal stinger or just what the heat actually does?



https://www.youtube.com/watch?v=q5FhK4Mar_E
Its PM07-18 from Panthera Motorsport
$6,340.00 USD – $6,980.00 USD

Volume/Bore/Stroke: 548cc / 94mm / 79 mm

Power : 92–102 HP *

Torque: 65–72 lb-ft *

Weight: 72lb / 32.7 kg

Transmission: 6 speeds

Exhaust control: Piston power valve
looks like they are also doing a 700cc version as well.

[Frits Overmars]

I have seen two well constructed home made dynos here. Both read lower than the Dynojet we use. We even did back to back tests between the home brew dyno's and the Dynojet. The home brew dyno's calibration was checked in various ways. Calculation, Rope pull and run down. I cant remember the difference but it was significant, maybe 10-12% lower than the DynoJet.You're quite right TeeZee. I did a comparative test at Ten Kate (multiple Supersport world champion) on their Dynojet with my hard- and software attached to that same dyno,
so each dyno run was registered simultaneously on both systems: Dynojet lies 11%.

[philou]

Extrude hone might be a good idea for transfer ports.
by smoothing the pressure drop zones


https://youtu.be/2QBc59YZYxA

[Frits Overmars]

Extrude hone might be a good idea for transfer ports.Not just for transfer ports. We could push it in at the carb (that's the bellmouth for you, Fletto) until it comes out again at the tailpipe. OK, that's exaggerating it, but in theory we could.

I happened to see something similar happen when someone dropped his bike during a race. The bike stripped itself of its fairing and came to rest on its side, rotary inlet side down,
in the sand next to the track, with the engine still running. For a short while anyway...:facepalm:

[sniemisto]

Thanks a lot for everybody’s input.

I prepared this cylinder time before I started reading pit-lane and this thread. I will now proceed with good info shared in here.

I do final matching of sim file power level to dyno result with adjusting combustion efficiency. In my case its as low as 0.72. I’m not sure if that is the best way. That way false dyno results have effect on combustion efficiency factor. That is affecting at least EGT of sim run. Maybe not that big issue in this case..

[TZ350]

I do final matching of sim file power level to dyno result with adjusting combustion efficiency. In my case its as low as 0.72. I’m not sure if that is the best way.

EngMod2T's sim is power at the crankshaft. It was a good idea but instead of abusing "combustion efficiency" I think EngMod2T has a dedicated adjustment method for adjusting your sim results to match your dyno and the power losses in the drive train.

Anyway I just look at the sim's KW line instead of the HP one. I have found that for my engine the EngMod2T's sim KW curve pretty much predicts the DynoJets HP curve. Lazy, crude and rude but works a treat.

[wobbly]

As TeeZee said EngMod is power at the crankshaft , and the difference from many , many racebike tests is that the DynoJet reads 12 to 15% lower than the crank number due to losses
in the transmission/chain and tyre contact patch - even though its already fudged upwards..
Dont adjust the Combustion Efficiency to fudge the crank number to be lowered to equal to the dyno result.
Take the dyno numbers , add a factor and create an EngMod dyno curve as the comparrison - this is in Post 2T.
Your real CE would lie somewhere between .85 for a low bmep and .95 for a real full house engine build - in a smaller bore high com on good fuel.

Extrude Hone was tested by Kevin Cameron many years ago when it first came onto the market - it lost power in every case with a two stroke.
I think DynoTech magazine found the same result , years ago as well.

[Condyn]

Extrude Hone was tested by Kevin Cameron many years ago when it first came onto the market - it lost power in every case with a two stroke.
I think DynoTech magazine found the same result , years ago as well.

I believe Dynotechs technical editor was Kevin Cameron.

[Brett S]

Internal stinger or just what the heat actually does?



https://www.youtube.com/watch?v=q5FhK4Mar_E
Its PM07-18 from Panthera Motorsport
$6,340.00 USD – $6,980.00 USD


It looks to be more just the welds affecting the thermal imaging camera rather than an internal stinger?
IR temp guns often have a refractive? index adjustment to allow for different metals/finishes/emmisivity etc.
In this case the dull weld area is showing hotter, when you would think with its extra themal mass would make it look colder when getting heated up.

[wobbly]

DynoTech Research - independant testing facility doing main Snowmobiles with an on line magazine subscription service.
I visited them when researching dyno facilities for the BSL500 - a very professional setup .
They were the first to actually document the real bad issues around loss of a fuels Vapour Pressure.
This is now why I insist on storing all fuel in 5L containers with no air space , and adding oil then using one at a time to prevent loss of the light front ends.
Amazing how much difference it makes. , not having blobs of un atomised fuel running thru an engine , making every apperance of being rich , when in reality its lean as hell.

[husaberg]

It looks to be more just the welds affecting the thermal imaging camera rather than an internal stinger?
IR temp guns often have a refractive? index adjustment to allow for different metals/finishes/emmisivity etc.
In this case the dull weld area is showing hotter, when you would think with its extra themal mass would make it look colder when getting heated up.

You are of course right son of Ken.
I was far too busy getting mesmerised by all the pretty colours that i never even noticed the massive enteral weld it loos like the chamber was made like an FMF or similar out of two large pressings
349664

that said it still doesn't explain the grid-like pattern.
Unless they are dolly marks?
349665

[husaberg]

I believe Dynotechs technical editor was Kevin Cameron.
Looks like some Kevin gems are here all right
http://www.dynotechresearch.com/blog/archives.asp?chosenMonth=5&chosenYear=2012



Extrude Hone was tested by Kevin Cameron many years ago when it first came onto the market - it lost power in every case with a two stroke.
I think DynoTech magazine found the same result, years ago as well.

I remember something about it years ago it was being used by the likes of some after market head producer for production stuff but could match a decent dude with a dye grinder
it was reminded by about the rig made by peter Wiliams dad to flow test a G50 or 7R head.
They were not allowed to buy a flow bench as it wasn't made by MAtchless AJS AMC or whoever they were at the time.
So he made a bench with a venturi out of an airbrush and it sicked through only and blotted on the areas of the head with no flow
He got (I think) a 10% increase out of a well-developed engine.

i googled and it looks like he was adding ink upstream of the fuel-air mix.


He was spraying ink into the airstream of the air/fuel mix going into the combustion chamber, and dynoing the results on an actual engine (using fuel/air, not air/ink !)
He found that if he could swirl the mix into the combustion chamber such that he didn't get any ink on the walls in the process, the bhp went up and up.
This added hp after hp on their already existing engine, all it needed was suitable gas flowing direction to achieve this - the porting specialists art.
The output rose from ~30 bhp to over 40 bhp over the years, although the engine was short stroked at some stage

That said Duckworth had some quip about how he could tell as much with an educated finger.

“Just by sticking my finger in the hole I can tell immediately whether air would like to go through it”.


https://www.motorsportmagazine.com/archive/article/january-1970/41/keith-duckworth
plus this

In complete contrast with the tape-operated automatic equipment, there is still no substitute for the human eye when it comes to “fettling” cylinder heads and inlet ports. Duckworth himself modifies the first of the chamber designs from his own knowledge, after which a man with a steady eye and a hand tool makes each one just like the last one. A Tracemaster copy milling machine is another recent arrival, capable of copying a pattern to plus or minus less than one thou " Duckworth says they're “hoping to rough combustion chambers out” with it, although it doesn’t mean the end of the hand-work."






Unrelated by still fun
Ford’s association with Cosworth became even closer in 1966, when a joint project was announced, not only for a new Formula Two engine designed to the 1,600-c.c. limit (a production block being required by the regulations this time), but also for a Formula One unit. This time FordÂ’s investment was an announced £100,000 and there is the added bonus of what Duckworth calls “encouragement”, not to mention the use of metallurgical laboratory facilities.
There is the oft-quoted remark that although £100,000 may sound like a lot of money, it had cost Ford £1m simply to put synchromesh on the bottom gear in the Cortina range.

[Pursang]

Oops! Redundant comment. (Always refresh before posting)

[koenich]

You are of course right son of Ken.
I was far too busy getting mesmerised by all the pretty colours that i never even noticed the massive enteral weld it loos like the chamber was made like an FMF or similar out of two large pressings
349664

that said it still doesn't explain the grid-like pattern.
Unless they are dolly marks?
349665

As already mentioned to some extent such a camera is measuring infrared radiation, which is highly depending on the surface finish/angle of capturing if it's a shiny surface. To do it right you'd need to black out the whole pipe and best case calibrate your camera with some surface temp couples...

[Brett S]

You are of course right son of Ken.
I was far too busy getting mesmerised by all the pretty colours that i never even noticed the massive enteral weld it loos like the chamber was made like an FMF or similar out of two large pressings

that said it still doesn't explain the grid-like pattern.
Unless they are dolly marks?



The black cylinder head is also very hot when they turn on the thermal imaging, which cannot be correct.

No idea on that dot matrix, i've never used a thermal imaging camera, only IR temp guns.
The dots don't seem to move when the exhaust moves relative to the camera, so must be something to do with the camera?

Edit: you can also see the white panther logo on the black clutch cover. They are the same temp.

[Brett S]

DynoTech Research - independant testing facility doing main Snowmobiles with an on line magazine subscription service.
I visited them when researching dyno facilities for the BSL500 - a very professional setup .
They were the first to actually document the real bad issues around loss of a fuels Vapour Pressure.
This is now why I insist on storing all fuel in 5L containers with no air space , and adding oil then using one at a time to prevent loss of the light front ends.
Amazing how much difference it makes. , not having blobs of un atomised fuel running thru an engine , making every apperance of being rich , when in reality its lean as hell.

Since you've said this in the past, i've always wondered if (depending on how the racing rules are written) you could pressurise your fuel with say propane to keep the light fractions from leaving the fuel? Might need a stronger fuel container though? It could even saturate the fuel with good stuff?

[Condyn]

https://www.drumpreserve.com/mobile/Section.aspx?code=featured

Take a look here. I think Jim (from dynotech) owns this company as well. Use nitrogen. It has been cited that Isopentane can be used to restore the lost Reid Vapor Pressure due to its high RVP number. I remember searching for other chemicals with high numbers and think acetone was very high as well. Always wondered if that would work.

We always RVP test our fuel after learning about the terrible fuel storage practices. Many VP 5 gallon cans are stale upon first opening and testing. C12 VP has always been good for me. Also seems to be the most common fuel at the track. (Snowmobiles I am talking) 114 is usually terrible.

Wobbly is indeed right, storing the fuel in small containers instead of cracking open your pail after every race to top off would be highly beneficial. An RVP test after every time you open the can will result in a lower number.

[wobbly]

I have always used dry nitrogen ( as we use for tyre pressure ) on my dyno fuel drum to maintain the RVP.
But I dont understand how using Isopentane or Acetone could be used unless there are no regs on fuel additives .
The vast majority dont get that leaving a fuel ( pumpgas even more than leaded ) if left in the bike or kart tank overnight , open to atmosphere , is virtually fucked the next day.
Using 1/2 a 20L drum after opening it several times , then opening the airspace to woosh away the next day, is also useless , I hate to think how many engines have been lost due to this small factor.
The lead in race fuel/Avgas doesnt evaporate away , so that can be restored somewhat even by adding some 98 pumpgas to aid in lifting the RVP and thus atomisation.

[SwePatrick]

A question!, version one vs version two(stinger/end of pipe).
I have done this change as version one was from 'taking what i had', now i have optimized it to be like version two, and now it suddenly want a lot more fuel.(from 220 main and 45 pilot to 240 main and 58 pilot, alcohol fuel)

Would a twostroker be that sensitive?

349673

[F5 Dave]

Diameters?

[wobbly]

The way you have drawn them both are impossible to build ( with zero wall thickness ) but version 2 with a step opposing reverse waves going up a larger diameter stinger, is what i have found makes best power when used as a short nozzle restrictor placed at the rear cone exit. It also needs more fuel.
How do you know the jetting was optimum to start with, as Methanol will run exactly the same , and making the same power , when up to 20%
rich over a huge range of flow numbers.

[SwePatrick]

Diameters?

Is that even a valid point?
My question is if the rubber forms a little volume(plenum) behind the stinger, it may create odd effects?

[SwePatrick]

The way you have drawn them both are impossible to build ( with zero wall thickness ) but version 2 with a step opposing reverse waves going up a larger diameter stinger, is what i have found makes best power when used as a short nozzle restrictor placed at the rear cone exit. It also needs more fuel.
How do you know the jetting was optimum to start with, as Methanol will run exactly the same , and making the same power , when up to 20%
rich over a huge range of flow numbers.

I shouldn´t comment, but do you think it is zero wall thickness? for real? :weird:
Not methanol, E85 this time.
Way more sensitive to jetting than methanol.(i´ve got huge experiance of methanol tuning)

Marked text is valid answer, my answer to that, is that i always build like so, but i was in a hurry and just took a hose i had(to large) and clamped it hard with hoseclamps, and it formed a little 'plenum' behind the restriction before entering the exhaustpipe.
I have dynoed it 86.7whp in my tough roller, (tzr250) with that weird setup, and now when fixed there is a loss.

[wobbly]

I only commented about the drawing having zero wall thickness , because as is usual in a 2T every small detail makes a difference.
As it stands i have no idea which way the steps go in each join - except for the stepped short nozzle version , but even thats not drawn with a bigger main stinger tube. Also one minute we are dealing with Methanol - next its E85 , how can anyone give helpful advice if the basic info is unclear.
Having a small plenum at the entry to the stinger may work like the stepped nozzle , creating same odd restriction to waves that are returning back up the stinger. I will give it a go by expanding a short section of plug in stinger tube and see what happens.

[F5 Dave]

Is that even a valid point?
My question is if the rubber forms a little volume(plenum) behind the stinger, it may create odd effects?
My point was to ask if they were different between drawings, they look different and is that part of the effect? But it wasn't clear. It looks like wall thickness is much more on bottom.

[SwePatrick]

Also one minute we are dealing with Methanol - next its E85 , how can anyone give helpful advice if the basic info is unclear.


I distinctly remember i wrote alcohol fuel..


A question!, version one vs version two(stinger/end of pipe).
I have done this change as version one was from 'taking what i had', now i have optimized it to be like version two, and now it suddenly want a lot more fuel.(from 220 main and 45 pilot to 240 main and 58 pilot, alcohol fuel)

[SwePatrick]

My point was to ask if they were different between drawings, they look different and is that part of the effect? But it wasn't clear. It looks like wall thickness is much more on bottom.

No diameter differences, silly me that guessed people would get that by my non precise drawing.
If i wanted to make a statement of it was different diameters i would have given that info.

The drawing is just a three minute sketch.

[Condyn]

Everyone wants insert nozzles. I prefer doing them out of sheet metal like the rest of the pipe to keep things more simple and less cumbersome.

[jonny quest]

Pump E85 is not 85. It's sometimes 83, 78, 93... you get the idea

[Muhr]

Hey all!

when we are on the subject, (in a way) maybe there is someone who has some smart solutions on jigs for welding exhaust pipes. We did this last night, felt like a smart solution when we discussed it, unfortunately I can now say that it was a pretty bad one ....

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/977BWjCMC8E" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

<iframe width="560" height="315" src="https://www.youtube.com/embed/v5jLX4KtpXs" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Flettners sliding gib throttle control.

<iframe width="560" height="315" src="https://www.youtube.com/embed/mS0cyt7F9js" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

360cc Mk2 TPI , Sliding Gibs throttle, first start up.

[wobbly]

Muhr , all the weld jigs I have seen or used , have the axis vertical with 3 sprung loaded pincer legs fixed to the 3 jaws.
That way by adjusting the 3 jaw diameter any pipe section can be gripped . Having the weld run horizontally past you gives a much better view of the seam approching the arc.

[teriks]

Pump E85 is not 85. It's sometimes 83, 78, 93... you get the idea
Even worse here, where there's "Winter E85" with even less ethanol to ensure cold weather starts.
I have so far never seen anything indicating what quality is sold.

Swedish standard SS155480:2006
• 70 – 86% etanol
• 30 – 14 % bensin
• MTBE, iso-butanol

[Condyn]

Muhr, I saw this on the fakebook a few years back. Always wanted to cut a hole in my bench and run the three jaw manually with a foot wheel with some drag on it. (I gas weld so no tied up foot)

[Flettner]

Just buy straight ethanol and mix your own.That way you get just what you want.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/av-pdf2Gt5g" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Flettners MK2 360 TPI.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/p1eoYLKlon0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

2Stroke Stuffing's latest adventure.

Its great to see people getting their projects running.

[Muhr]

Muhr , all the weld jigs I have seen or used , have the axis vertical with 3 sprung loaded pincer legs fixed to the 3 jaws.
That way by adjusting the 3 jaw diameter any pipe section can be gripped . Having the weld run horizontally past you gives a much better view of the seam approching the arc.


Muhr, I saw this on the fakebook a few years back. Always wanted to cut a hole in my bench and run the three jaw manually with a foot wheel with some drag on it. (I gas weld so no tied up foot)

Thank you! I had hoped to be able to make something that can withstand when it is loaded at an angle when it begins to twist. I'll try to do something as below.

[Flettner]

Took the 360 out for a tuning run yesterday, didnt go as planned, charging system stopped working bugger it.
It had moments of brilliance.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/sO-3ukNQW04" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Flettner. The 360 Lives .......:scooter:

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/sPd6VJQeSYw" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

How a two stroke sleeve valve engine works.

<iframe width="560" height="315" src="https://www.youtube.com/embed/bwsu5td6nko" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Flettners two stroke sleeve valve engine running.

349723349720349721349722

[wobbly]

Anyone know of where a TZ250 H J may be hiding here in Aotearoastan.
There was one in the Morley Engineering Superkart , and another that came out of Gingers kart and went into a YamaGamma built by John Reid.
Cheers

[husaberg]

Anyone know of where a TZ250 H J may be hiding here in Aotearoastan.
There was one in the Morley Engineering Superkart , and another that came out of Gingers kart and went into a YamaGamma built by John Reid.
Cheers

pretty sure that was john reids old yamagamma chassis that wa sold a few weeks ago wasnt it.
349728

looked like a TZ rad and a Dymag rear and.

[wobbly]

Yep trying to find the engine for that chassis.

[husaberg]

Yep trying to find the engine for that chassis.

Have you tried the Wiltons
if its around i would say they might know where it was.
Ps Did it was with that 16 front wheel?

[jbiplane]

Our very small 50x50mm open source boards (Speeduino compatible can be programmed) are manually soldered and ready for testing. Pressure, air temperature sensor and non-contact magnetic position of the throttle valve are on the board, but it is possible to connect external ones. Both inductive and Hall crankshaft and camshaft sensors are supported. A bit more extended version will have CAN support + temperature control under spark plug and exhaust gases.https://reaa.ru/attachments/speeduino-compatible-in-drossel-jpg.486520/

[diesel62]

Well done

Sent from my SM-P555 using Tapatalk

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/r1CUbIYnlPI" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

2Stroke Tuning. When things go wrong .......

<iframe width="560" height="315" src="https://www.youtube.com/embed/2hYUBM4iLuw" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

2Stroke Tuning supercharged 50 is running better now ........

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/pCnbBYp96Gk" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Hill climbing with a H2 750 Kawasaki, great sound of a 2Stroke ripping it up.

[ken seeber]

For the DCI engine, which seems to work, the next thing is to find out if it offers anything in terms of increased power. So, need a dyno. Decided to make one that fits directly onto a kart, swinging off the LHS of the rear axle. So, with a couple of Ø40 bearings and a Commodore front disc and caliper and some bits in between, the thing is now sort of in place. The torque reaction will be measured by a 50 kg strain gauge, which with a readout, was kicking around from another ongoing project.
Once working, the plan is to fit a standard ARC piston ported inlet cylinder to the engine and then do a baseline power run. After that run the DCI engine, firstly with the pissy little snipper carbs we have been using and then fit some larger Tillotson ones….this will be the real test.
Being a friction brake, I hope we can control the thing, manually, such that we can hold it at constant speed points, enough to optimise the mixture (which could be anywhere at present) and get a torque reading. If we used an inertia dyno it’d take years to get a decent clean carburation operation over the rpm range.
Also, I can use it to test the unfinished slider engine project, which fits straight onto the kart.

349751349750349752349753

[TZ350]

For the DCI engine, which seems to work, the next thing is to find out if it offers anything in terms of increased power. So, need a dyno. Decided to make one that fits directly onto a kart, swinging off the LHS of the rear axle.

Great work. I am totally looking forward to the comparative dyno results.

[jonny quest]

Beef up your torque arm. That will flex way too much for consistent readings

[Muhr]

I am thinking 15-20 kgf which is gradually applied with a caliper, should it handle or? or is it something I do not understand?

[F5 Dave]

Another Commodore out of commission. I applaud your efforts even before we know if the engine is a grunter.


Can you take out a few Fiord Rangers too? :laugh:

[ken seeber]

Dyno brake disc thoughts:

In my case, am considering an engine of say 15 kW @ 10k rpm. Doing the mathS, this equated to a torque of 14.4 Nm. With a chain reduction ratio of 8:1, this means the axle is seeing 116 Nm.
With the current setup as in the pics, the strain gauge is aligned to be tangential to the axle at 300 mm. So the force it will be seeing is 116/0.3 = 386 N. The strain gauge is rated at 50 Kg = 491 N.
Compare the forces for the brake arrangement in a car. 1500 kg, 0.5 g de-acceleration and a wheel rolling radius of 330 mm. Force to slow the car is 1500 *9.81/2 = 7358 N. Say if all 4 wheels share the braking, then each wheel sees a tangential force at the ground of 1839 N. The torque at each wheel is 1839 * 0.33 = 607 Nm. Well safe.

Weight. Weighed all the major individual bits, totalling at 19.2 kg. Thought it’d be more when my dainty, but aging body had to lift them up and down all the time when making them. Thus the load on the axle is low when compared to a kart weight of 160 kg with a 60:40 distribution = 48 kg per rear wheel.

Will it shake due to flex? Dunno. The arm is certainly strong enough rotational inertia of the disc will act as a juicy flywheel, so I think the thing will be relatively smooth.

It is what it is.

Dave, everyone loves a grunter….:laugh:

349756349757349758

[Muhr]

Dyno brake disc thoughts:

In my case, am considering an engine of say 15 kW @ 10k rpm. Doing the mathS, this equated to a torque of 14.4 Nm. With a chain reduction ratio of 8:1, this means the axle is seeing 116 Nm.

I built my assumption closer to 4: 1 eg 11-44.
Just want to say that I did not try to be a dick regarding the potential success of the project!

[ken seeber]

I built my assumption closer to 4: 1 eg 11-44.
Just want to say that I did not try to be a dick regarding the potential success of the project!

Muhr,

You are a contributor and absolutely NOT a dick. Keep on keeping on.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/QdHSZz2IysA" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

I just love the sound of this ........

[wobbly]

I really hate it when U Tubers do dyno runs like this and dont simply turn the camera around and show the graph on the screen.
Suter must have done 20 videos showing the thing screaming thru the gears - not one dyno graph I can find anywhere.
Rant over.

[philou]

Sorry, vidéo in french.

he uses a sheet of paper to visualize the scavenge


https://youtu.be/t1b3MpWFtOo

[husaberg]

cool idea, i give up, why is the frenchmans septums so sharp?:scratch:

Is it as fast as a F104
349780
https://qph.fs.quoracdn.net/main-qimg-77b857355e8c8587f16b92078a54d50f-c

[JanBros]

cool idea i give up, why is the frenchmans septums so sharp?:scratch:


he says he didn't touch the original concept of the engine, he just wanted to optimise/even out the flow of the original concept. not a bad result.

[Hoebra]

If you like triple or twincylinder sound, here`s a clip of a twin project a friend of mine and me build last saeson, just for dyno competition where 88cc was the limit:

https://youtu.be/A6qjmcgAO1Q

The frame is a dutch replica of an privat eastgerman selfmade chassis of the late 70`s, the engine in base is from a Simson S51, in serial condition 50cc, 38/44 bore/stroke, aircooled, pistonported 3,7CHP.
We changed it to 180° twin, shortened te stroke to 37,8mm, added reedvalves (rotary disc was forbidden), turned the cylinders 180°. Still with iron sleeve inside, no nicasil or other ceramic coating. Carbs are 28mm Keihin clones.
So its 42,9ccm per cylinder, 85,7cc in common.

We createt a header with variable length to enlarge the powerband. Unlfortunatly the servo was to weak to manage the planed way of 90mm, so we had to reduce it to 30mm 2 days before Competition. While Tuning a bord of a inner bearing ring broke and damaged 1 piston/cylinder/crank. In legg of oversize piston we coated an new piston an honed the cylinder +0,1mm. it "worked", but the coated cylinder gave constantly 2 PS less over the whole powerband than before, so in best condition it should be round about +2PS (and about 1000rpm earlyer starting power band if the servo woud work the whole way).

The dyno curves have some dimples, because the dyno we used for tuning has much less inertia then ne one which was used in Competition, so time for acceleration and heating changed a lot. Hope you like the sound.

edit: pictures now visible on next page.

[andreas]

Sorry, vidéo in french.

he uses a sheet of paper to visualize the scavenge


https://youtu.be/t1b3MpWFtOo

Seems like such an unscientific method, and it's up 5-6 Nm over a wide range. Is just bogus?

[Frits Overmars]

If you like triple or twincylinder sound...
https://www.simsonforum.net/download/file.php?id=31424&mode=view
https://www.simsonforum.net/download/file.php?id=31422&mode=view
https://www.simsonforum.net/download/file.php?id=31423&mode=view
https://www.simsonforum.net/download/file.php?id=31427&mode=view
https://www.simsonforum.net/download/file.php?id=31428&mode=view
(https://www.simsonforum.net/download/file.php?id=31428&mode=view) Hope you like the sound.I did like the sound Hoebra, but I could not see anything on those simsonform.net links.

Du hast keine ausreichende Berechtigung, um die Dateianhänge dieses Beitrags anzusehen.I would be grateful if you could show your pics right here.

[Hoebra]

349783349784349785349787349786

I tried this before but failed, I think now they should be visible?

[Hoebra]

two more pictures.

[wobbly]

Husa its well known that the YZ125 transfer flow is above supersonic , NASA has had this in their Mars lander for years ,so sharp septums ar de rigueur in this case.

[Frits Overmars]

I tried this before but failed, I think now they should be visible?Yep, thanks. Interesting pictures :niceone:

[DoldGuy]

Husa its well known that the YZ125 transfer flow is above supersonic , NASA has had this in their Mars lander for years ,so sharp septums ar de rigueur in this case.

Wobbly, I’ll be the one with the dummy questions as I didn’t know, what effect does this have on the divider/septum? And can you offer a simplified understanding of the intake resonance/ frequency and the need of different lengths of intake tracts?
Thanks in Advance.

DoldGuy

[wobbly]

The septum is there really only as the A/B port duct walls are differing radial angles , and having a knife edged entry to both these ducts creates eddies or turbulemce that can only disturb the flow
regime.The Aprilla septum was about 10mm wide on the outer wall ( a flat ) with radius edges into both ducts , as the wall angles were very different.

Re intake tuning. The two scenarios we are interested in are RV and reed.
The RV intake has to be made as short as is physically possible , this takes precedence over any sonic tuning , in that we have the issue of resonant waves bouncing off atmosphere - firstly as a closed ended
tube when the RV is shut , then in helmholtz resonance with the case .This can cause the same air/fuel mixture to pass the emulsion tube/needle up to 3 times, in and outward.
Creating havoc with trying to get a useable tune.

In a reed we have a completely different scenario.
Intake tuning in this case is easily seen to be working in EngMod . We have the case gradually going into a negative pressure ratio around BDC due to the pipe and then the piston starting to rise.
As well as this we also have the intake tract seeing a cyclic wave travel up and down its length , from just past the bellmouth , and to ,on average about 2/3 of the reed port length ( as this varies as the petals lift ).

If you tune this intake length to give a 3rd harmonic positive pressure ratio arriving at the reeds , at the same time as the case goes negative , around the rpm you want , this pulls the petals off the ports as fast as is possible.
This + and - pressure ratio point slowly moves away from around BDC as rpm rises , and the result is that the reeds are giving usefull flow into the case at around TPC , much earlyer than would be the case without both
elements working together.

Here is a running EngMod file showing the case going negative at the same time as the intake goes positive , in this engine @ 10,000 rpm

This tuning makes a mockery of what we see on MX bikes , where due to room constraints , the exact same intake length of reed/manifold rubber/carb are used on a 125 as well as a 250.
How can the intake tune be correct for both - it isnt.

[husaberg]

Wobbly, I’ll be the one with the dummy questions as I didn’t know, what effect does this have on the divider/septum?

DoldGuy


What never ceases to amaze me is the inner curvature of the Honda transfer ducts. Even in their most recent race engines it was only 12 mm at its tightest point,
compared to a constant 22,6 mm radius for the Aprilia's inner curvature - that's almost twice as big, which makes a big difference in flow attachment.
336552
349792349794349795349796349793

[speedpro]

So, with a couple of Ø40 bearings and a Commodore front disc and caliper and some bits in between, the thing is now sort of in place.
Being a friction brake, I hope we can control the thing, manually, such that we can hold it at constant speed points, enough to optimise the mixture (which could be anywhere at present) and get a torque reading. If we used an inertia dyno it’d take years to get a decent clean carburation operation over the rpm range.

I built a similar setup with the brake for my fuel injected bike as I too needed to hold a load at set revs to see what the fueling was doing. In my case I used a roller and frame and mounted the bike to it. It wasn't too hard to hold the revs at set points with a long handle operating the brake. You will have problems where the engine is coming on pipe and power is increasing quickly. A little too much brake will drop it off power and too little will have the engine screaming. A bit of practice will help. I found it easier to have the engine rev over the rpm you were interested in and to pull it down with the brake. One person doing both brake and throttle although once you sort it out it works with 2 people as well. Data logging is a big help. Disc and caliper both retrieved from the scrap bin of the vehicle compliance centre.

349797349798

[Frits Overmars]

Here is the simple version, for on-site minibike tuning at the track. The drum has enough inertia so it can also be used as an acceleration dyno. The small brake disk and caliper have their limitations however; long runs would quickly overheat them.
349800 349799

When we first used a disk brake for power measuring (in 1972 I think it was), we had the disk run partly submerged in a water basin. That solved both the thermal problem and the dust problem in our dyno shed :msn-wink:.

[TZ350]

When we first used a disk brake for power measuring (in 1972 I think it was), we had the disk run partly submerged in a water basin. That solved both the thermal problem and the dust problem in our dyno shed :msn-wink:.

Water basin for cooling the disk and dust suppression. Great idea. Thanks.

[Larry Wiechman]

I've used a machinist's coolant spray mister to cool a vented truck rotor. Aim the spray inside the rotor so the coolant exits through the interior vents and does not affect the friction coefficient of the brake pads. Properly adjusted, there is no mess. https://www.amazon.com/Coolant-Lubrication-Spray-System-Milling/dp/B01C74DL98/ref=asc_df_B01C74DL98/?tag=hyprod-20&linkCode=df0&hvadid=312244744965&hvpos=&hvnetw=g&hvrand=5304498010637502943&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9021874&hvtargid=pla-524764684955&psc=1

[jfn2]

Wobbly or Frits
Sometime a while back one of you guys were talking about getting more HP by running a lower compression ratio. I came across a setup that runs very good and uses lower compression. I was wondering what parameters' you would want to change to run a lower compression engine? Say from a 180-200 psi cranking pressure to 130-145 psi pressure. This is in a 350cc TZ (old school engine). Thank you.

[Frits Overmars]

Wobbly or Frits
Sometime a while back one of you guys were talking about getting more HP by running a lower compression ratio. I came across a setup that runs very good and uses lower compression. I was wondering what parameters' you would want to change to run a lower compression engine? Say from a 180-200 psi cranking pressure to 130-145 psi pressure. This is in a 350cc TZ (old school engine). Thank you.In principle I do not want to have anything to do with cranking pressures. The only thing they're good for, is a comparison between what your partical engine had before, and what it has now. If it's become worse, your piston ring, or the sealing between the ring and its groove, may have reached the end of their useful life.
I hear rumours about engines with inlet and exhaust valves, the so-called foul-strokes, and cranking pressure measuring may have its uses in such cases, but let's not go there.
And while we're at it, I don't want anything to do with so-called effective compression ratios either.

The idea behind more power from a lower compression ratio is, that the lower compression ratio before TDC equals a lower expansion ratio after TDC, which leaves more energy in the combustion gases by the time they enter the exhaust pipe. If that pipe is really effective, you may see your power gain. If the pipe is not, don't bother. And I'm pretty sure that Wobbly will feel the same about it.

[wobbly]

I agree with Frits , part of a power gain to be had resides in how efficient the pipe is - and in the TZ350 case the pipe is not.
But of more importance is the relationship between ignition advance and compression.
There is a fairly narrow range for both , and max power available from whatever combination is totally dependant upon the fuel.
The optimum for leaded race fuel is tipped heavily toward high compression , minimum advance , and lean as hell to get heat in the pipe without deto.
Unleaded fuels are the opposite , lower compression , more advance and a richer mixture are the direction that gives best power , again just short of deto.

So , just concentrating on compression is a mistake - there will be gains to be found by varying the ignition advance.
But as always , no free lunch , as you wind in advance , you will be reducing the energy transferred to the pipe , so its a balancing act to get the overev rpm and a higher power level, thats dictated by the fuel characteristcs.
And unless you have a modern ignition , the old factory setup only allows static to be wound in , and this automatically restricts overev.

The TZ350 has a modest BMEP ( partially due to the pipe limitation ) so the dynamic compression is not that flash. Thus for the fuel being used , more power is to be had by having a higher static compression.
Also in this case , having a lower compression , that will allow more pipe heat energy and thus more overev , will be of limited value , as overving the TZ with porting/pipe that simply wont support high rpm power will end
up reducing the mid , more than it gains up top.

[SwePatrick]

<iframe width="560" height="315" src="https://www.youtube.com/embed/QdHSZz2IysA" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

I just love the sound of this ........

My build :love:
Not me filming, it was the owner of the bike the engine belongs to, who filmed it(and a dutch stole the vid and earned a lot of money on it)
It runs even harder now, but i have changed the dynosetup from performance trends to sportdevices so numbers aren´t comparable.
But we have run into problems, we need to modify the clutch as the one´s we tested can´t take the power.
We dynoed 68hp in new dynosoftware WITH slipping clutch.

I am impressed by the engine so far, NOTHING has happened to rotary assemble(crank,conrod,piston)
We ran with huge clutch problems low 8´s in quarter mile this summer, we ran about 30runs, no issues at all besides that clutch.

We actually run quite small carburetors(lectron downdraft 34mm)
We have a 38mm setup also, but we need to figure out the clutch first and make use of the power it produces as is first =)

At the very dynoday of 68hp we ran locked cvt to figure out how the powerband looked like.
The last pull of the day when i have freshened up the clutch and washed it with vinegar essence(old trick) it actually hold the clutch, for a while until the belt broke..
That pull just before the belt said goodbye the powerband was 13hp higher at the point where it happened.
So dreaming of that 13hp could be all through the whole powerband it might have been 81hp

And,, it runs HARD!!
Just need to dial it in, but covid has taken out a lot of races in Sweden this summer so we only had one to go to.

[jfn2]

Thank you very much, wobbly and Frits for your reply's. Do I have it right in saying..... If I come up with a good pipe design and I have the ignition correct and I use lower octane gas I will get a power increase if I use lower compression. But if I came up with a good pipe design and I have the ignition correct and I use higher octane leaded gas I will get a better power increase because compression is power? The engine I am working with is a 340cc twin for a snowmobile. Bore is 62mm, stroke is 55.6mm and con rod length is 112mm, so it is very close to a TZ 350 Yamaha. I understand about the TZ pipes. I have been trying the dimensions in Greg Bennett's book on Yamaha racers but have yet to come across one that gives very good power. I set my rev limit to 11-12250 rpms for peak in Engmod2T but still working on it. Again thanks. Jeff

[Condyn]

Try closer to 10,000 rpm for that Polaris 340. Try a TL of around 1040-1050mm with a 32-33% header 66%ish diffuser and see where that gets you. I run 15:1 compression on my twin Yamaha sled engines right now but also plan to try to develop something closer to 12.5-13:1 on the next build. The only reason I have not done that yet is the large amount of pipes I have built for the 15:1 engine.

[wobbly]

The TZ350 pipes are limited by being able to find room on the bike and to stop corner grounding.
Also the fromt wall of the A port isnt angled back enough and anything like a good pipe would short circuit like hell.
The 350 bikes/pipes I have built using modern ignitions are all done by 11000 @ 80 odd Hp on Avgas , but in Dr Jeffs LSR engine it ran 110 octane with 17:1 and would redline at 12,000 all day
with fat pipes ( 128 ) and 1280* on the egt with over 100 Hp.

[jfn2]

Condyn
Yes I have been working with 33% and 66% pipes on 950mm pipes and they seem to be coming up pretty good. The 950mm pipes seem to max at 10500rpm and I have ran a pipe with 40% and 66% at 950mm and it tops out at 10250 and it pulls strong. But I feel the motor should pull around 11750rpm. But if wobbly said he could get good power at 11,000rpm that's good for me. The problem is I'm not getting near 80 hp but I'm working on it. Thank you for your reply. I saw the pic of your sled you posted. Nice looking pipes. What does the plaque say on the pipe?

Wobbly
Thank you for your reply about the 350 Yamaha's. I'm going to have to go with reeds on this engine if I'm to get much more power out of it. I did one of these engines back in 1973 and it dyno'ed at 66 hp and I thought that was good with what we knew back then. But I installed reeds then. Who is Dr Jeffs? And what is a LSR engine? Thank you for all your help. And I will look into the 'A' port angle.

[wobbly]

The TZ350 engines in racebikes will rev to 11,000 but the 80 RWHp is down at 10500.
Here is all the info ( short of seeing the EngMod file ) on getting 100+ Hp from a TZ350.

https://www.facebook.com/jhenise/posts/10158657273846228

This has reeds fitted on it so is really relevant to what you are wanting.
Its Dr Jeff Henise's Land Speed Record holding TZ350 , at Bonneville it broke the speed record @ 170.519 mph on petrol , non streamliner , stuck in 5th gear pulling 12,000 - 200mph is achievable in 6th.
That engine used a bored TZ250 G cylinder with a Banshee 58mm stroker crank.

The other point is that you will never get any race engine to make decent peak power , and to have overev , with anything like a 40% header.
If anything nearly all the conventional pipes I do these days are closer to 30%.
The header and short first diffuser length total ,heavily influence peak and overev performance , the diffuser end cones length and angle shapes the front side power.

Edit - to help you out here is nearly the final pipe version , Lt 925 peak power @11250 - this was 3 years ago and I would do it somewhat better now.

[Condyn]

Jeff, 11,000 is not out of the question for the 340 if you can somehow get enough blowdown. 10,600 rpm is typically what the highly developed champ 440s run at with 990-1025mm pipes. Not sure if that is because the CVT limitations orÂ…?
When I dynod my 36% header pipes with the idea of delaying the diffusers pull on the bad transfer geometry which includes a bad A wall angle, shallow (less than 3 degree Angle headers) simply would not rev off its arse. Most all snowmobile pipes from vintage engines that I have measured from builders supposedly in the know have 29-31% headers. I have not tried anything that low in engmod or real life yet. Now that Wobbly mentions it, I will order some metal pronto and build the same pipe with a stubby header and same diffuser percentage.

The tag is just a way for me to keep track of them. No business name or anything like that.

[wobbly]

I did several engine/pipe setups for winning Champ 440 engines many years ago , and yes 10500 rpm with a 1000 pipe.
I do remember being told to keep it at 10500 but not why , most likely CVT tuning as you say Condyn.

That was one of the first times I had used the 75% duct exit idea on a customer engine , and when I published the drawing of my pipe setup along
with the reference Jaws pipe , and the dyno result , it created a huge stink.

Even though my pipe made way better power , some people got their panties in a real knot because I had published their medeocre " IP ".
They then swiftly said they now had a better design , but when I challenged them to "show me the money", nothing but silence errupted.

[Condyn]

Are you surprised? Americans are more likely to buy snake oil from a silver tonged devil salesman with a big name like RK TEK than to take a premium bone tossed in their direction. Modern 2t tech is hard to push on the dynomation crowd.

[Flettner]

Are you surprised? Americans are more likely to buy snake oil from a silver tonged devil salesman with a big name like RK TEK than to take a premium bone tossed in their direction. Modern 2t tech is hard to push on the dynomation crowd.

Isn't that the truth..... RK with their potato chip head.

[F5 Dave]

Nah that's old tech, we need something new to sell. But what? Thinking.

Got it! Concentric grooves! :devil2:

But which way?

I know. :banana:

Clockwise for the northern hemisphere and anti clockwise for southern. You know because. . .

You machine some up and I'll start on the Farcebook page.

[crbbt]

But what if you live near the equator?

[F5 Dave]

Clearly you need a twin cylinder with one each way. . . . If you are heading East.

Send your money to. .

[TZ350]

.

https://youtu.be/Xm6xxV6lFS8 somewhere in here is a Nitrous H2 Kawasaki.

https://youtu.be/PSq33KMwZn8 Super Bowl of two stroke motorcycle drag racing.

https://youtu.be/9XWKXNQqa-Q Kawasaki H2 750 of Bill Baxter and Alex “HRP” Hughes take on the wild nitrous oxide two stroke Kawasaki H2 750 of Jim Chongris.

https://youtu.be/eRItqiCFuQE The fuel injected Kawasaki H2 750 of Bill Baxter's.

[jfn2]

Wobbly
Again thanks for the pic's and pipe diagram and for the % info. I see that the center pipe dim is way up at 130ish. I though the only way you could use that high of center area draw was if you had a very good scavenge setup. I think the engine I'm working on has only 120mm center to center bore distance with a 62mm bore. That doesn.t leave a whole lot of room for the inside transfer port duct curvature. I also can use a monobloc set of cylinders to help with the inside transfer duct curvature. What scavenging model do you use with a TZ350? I've been using Yamaha 14.

Condyn
Yes I agree with you, the blowdown is the big problem. I intend to resleeve and use a T-port exhaust. I think I can use a 4mm thick sleeve out of alum and nicasil it. I don't have much of an option. And yes I also believe the cvt is a problem. The factory uses clutches made out of magnesium, both front and back. And I have a race sheet from the factory that names what specs to use and in big bold letters say not to exceed 12500 rpm. I believe this is for the magnesium clutches. And It was signed. But I can't confirm it.

[TZ350]

349839

The PS92N Crain coil, DCCDIP2Race Ignitec ignition and Champion C53VC 694 surface gap spark plugs have just arrived for my 250cc rotary valve methanol burning Post Classic pre72 Kawasaki. Should be fun.

Wob tells me that dumping both sides of the twin cylinder Ignitec CDI ignition unit at the same time into the low impedance Crain coil and a very cold plug is the hot go for my single cylinder methanol engine.

349840

Not my bike, but it gives you an idea of what I am aiming for.

[wobbly]

The TZ350 has maybe being kind , Yam 6 in stock form , but when using a bored/stroked TZ250G with reeds/boost ports , and reworked angles its for sure Yam 14.
And that allows fat pipes to make serious power - no reason yours could not have the same , if the A port front wall is re angled.
The RD/TZ series has 102 bore centers , way worse than yours with near the same bore .
We would kill to have 120 , and yes a monoblock can help dramatically - as we have using CPI cylinders on the YPVS / Banshee with only 102 centers.
But fitting anything bigger than just over 120 diameter is brain damage on a YPVS or post classic racebike.

[SwePatrick]

I use a simple PVL dual coil and NGK br9ecmix plugs in my total loss ignitech system(just a 4amp lithium battery, dragracing) same system as you TZ350, but for one cylinder, with dual coil to fire two cylinders.
I run e85 in my TZR250 engine, no hickups no nothing.
I also ran the system with single coil(PVL) in my kawasaki engine(1cyl methanol) and dynoed almost 70hp from that one(same sparkplug), no problems at all.

Sometimes i wonder if the interwebs is recommending the expensive stuff just to make it hard for people to reach their goals ;)

The dual coil.
349841


https://youtu.be/-iEvQKSIVTw

[TZ350]

I also ran the system with single coil(PVL) in my kawasaki engine(1cyl methanol).

I have a single trigger and would be greatfull for any tips on setting up the Ignitec software to fire both sides like you do with your Kawasaki single.

I love the sight and sound of your TZR250. https://youtu.be/-iEvQKSIVTw .

[philou]

Sometimes i wonder if the interwebs is recommending the expensive stuff just to make it hard for people to reach their goals ;)



not necessarily

we with ignitech are seeing a loss of power on the rgv and nx4.

bridging of the 2 outputs, big coil and voltage of 16 V minimum. to achieve the same power as the original cdi.

ignitech has a badly matched converter or capacitor or too low capacity to deliver enough milli joules

many have abandoned them to return to the original cdi, or to turn to other manufacturers for race use.

it is not a racing cdi, the electric power collapses after 10,000 laps.
good replacement for road bike.

349842349843

[wobbly]

All DC DC CDI ignition systems are extremely sensitive to matching of the output impedance of the voltage converter to the inductive reactance/resistance of the coil. Many have tried to simply replace the NX4/5 ecu with an Ignitech and use the stock coil - it doesnt work ,end of. As its inductive reactance is too low and its static resistance is too high , this is not a fault with the Ignitech, it is simply an operating hardware mismatch.
Honda chose a very different converter operating window for their version of a DCDC CDI system.

There are limited choices to increasing the ionizing voltage and or increasing the plug gap burn period and " power discharged " - lower the primary series resistance ( under 0.2 Ohms ) , increasing the coils inductive reactance and finally increasing the power supply voltage.
Using both CDI capacitors in parallel is a simple brute force way of doubling the available discharge energy , but this does not address the impedance mismatch that sets the burn period of the system.

The Crane coil as is used in NASCAR cdi systems , when used with the twin outputs pulled over 4.5 Amps compared to just under 1,5A with a single cdi and conventional coil - the burn period was tripled on the scope app, exactly what is needed for high compression and very rich Methanol mixtures , required when trying to emulate the natural operating parameters of a water cooled engine with an air and chemically cooled two stroke.

[philou]

1.5 A in my opinion is not sufficient for racing use.
this should hardly exceed 30 millijoules spark plug. Road utility

with 4.5 A it's ok. it must be over 50 millijoules. which must be a minimum for an engine compressed with a high msv and overred.

the Crane coil and in my list of things to try. the resistance and impedance characteristics are very interesting.

[jfn2]

Wobbly
I just measured the bore centers on the engine I have and I was wrong, instead of 120mm they are only 115 center to center. I'm sorry I must wrote down the wrong number when measuring the first time.

[TZ350]

.

Keeping up with 2Stroke Stuffing's progress with his supercharged nitro 50cc two stroke https://youtu.be/HRSmWfsvS2I

.

[Condyn]

Pardon my ignorance to machining, I understand how the squish band gets cut in a lathe but how is the concave radius of the dome cut in a manual lathe? I watched one video of a round boring bar being rotated up with the bar holder for cutting a similar part. Is this the common method? I also seem to remember Dr. Jeff cutting a toroid chamber with a manual machine too but cannot find that anywhere. Sick of paying for my head work. It is time to buy a lathe and some tooling and learn.

[wobbly]

In all the RD/TZ and YPVS/Banshee race bike engines I have built - probably 20 in total, I have used DC DC CDI P2 into cheap knock off Ebay , Aprilia RS125/250 coils ( never had a failure )
This draws about 1.5 amps per cylinder into the ECU, and the most powerfull was a Banshee based CPI 400 engine in a Pre 82 Post Classic road race bike with 96 RWHp at 11,000 rpm.
That bike won the Sheene Post Classic TT champs, and broke the lap record by 2 seconds.
All the bikes used CR250 DC type stators that gave 14.2 battery charging voltage ECU input. Using R7376 plugs I have never once had a problem with ignition related power loss.

I tried a DC DC CDI P4 with the paired outputs paralled into the the two same coils on a 82 RWHP TZ twin, this gave exactly the same power on the dyno. - proving to me that ignition milli joule supply was not a limiting
factor in that case at all.
And a TM KZC big bore 152cc that made over 62 Sprocket Hp @ 13800 rpm on pump gas - no spark breakdown issues there either.
Recently I tried , simply out of interest , swapping The Ignitech P2 on the Banshee 400 CPI bike , for a Zeel VPCD20 - programmed exactly the same it gave 2 Hp less but on a different dyno , so good enough for me but also
alot more expensive .The hand held programmer box with no laptop to drag about is a real help at the track though , so I would choose that if the customer was happy to pay for the convenience.

Also a KTM250 road race engine making 70 RWHp at 10500 on Avgas - so I really do dispute anyones statement that the Ignitech is only good for road use as its not " powerfull " enough.
The Crane coil with paired outputs was developed for 125cc offshore hydro use , running 20:1 compression on Methanol at 14000 rpm , a really extreme case.

[Flettner]

This one runs an Ignitech single cylinder, on E85, toridal head, 8mm plug. Seems so far to run alright.

[wobbly]

Condyn , here is a toroid setup for a 66mm domed Banshee setup.
The straight squishband with 0.9mm squish at the bore has virtually no ( 0.34mm ) taper when transitioning into the bowl.
This is a wide squish with a fairly big dome and imho using a tool post rotation device to match the piston dome radius is simply not worth the effort.
The actual insert was CNC machined , but even then I didnt bother doing a radiused squish.

[OopsClunkThud]

Pardon my ignorance to machining, I understand how the squish band gets cut in a lathe but how is the concave radius of the dome cut in a manual lathe? I watched one video of a round boring bar being rotated up with the bar holder for cutting a similar part. Is this the common method? I also seem to remember Dr. Jeff cutting a toroid chamber with a manual machine too but cannot find that anywhere. Sick of paying for my head work. It is time to buy a lathe and some tooling and learn.

a hemisphere of any radius can be cut on a mill with the spindle set at an angle and rotary table. you are cutting the edge of a spherical cap and by rotating the part it cuts the hemisphere. Not hard to sort out in CAD what the angle and diameter should be, I can dig up my notes.
349846


I think the good Dr. did the toroid with a large ball endmill, again with the rotary table but no need to angle the head.

[Condyn]

Thanks for the replys.

Wobbly, I actually have a toroid drawing for my heads that you drew for me a few months back. I plan on having my friend CNC it when the machine is free. ( NEVER )

OCT, Interesting. That seems like a nice method. I would be interested in any additional info you can dig up. Much appreciated.

[husaberg]

In all the RD/TZ and YPVS/Banshee race bike engines I have built - probably 20 in total, I have used DC DC CDI P2 into cheap knock off Ebay , Aprilia RS125/250 coils ( never had a failure )
This draws about 1.5 amps per cylinder into the ECU, and the most powerfull was a Banshee based CPI 400 engine in a Pre 82 Post Classic road race bike with 96 RWHp at 11,000 rpm.
That bike won the Sheene Post Classic TT champs, and broke the lap record by 2 seconds.
All the bikes used CR250 DC type stators that gave 14.2 battery charging voltage ECU input. Using R7376 plugs I have never once had a problem with ignition related power loss.

I tried a DC DC CDI P4 with the paired outputs paralled into the the two same coils on a 82 RWHP TZ twin, this gave exactly the same power on the dyno. - proving to me that ignition milli joule supply was not a limiting
factor in that case at all.
And a TM KZC big bore 152cc that made over 62 Sprocket Hp @ 13800 rpm on pump gas - no spark breakdown issues there either.
Recently I tried , simply out of interest , swapping The Ignitech P2 on the Banshee 400 CPI bike , for a Zeel VPCD20 - programmed exactly the same it gave 2 Hp less but on a different dyno , so good enough for me but also
alot more expensive .The hand held programmer box with no laptop to drag about is a real help at the track though , so I would choose that if the customer was happy to pay for the convenience.

Also a KTM250 road race engine making 70 RWHp at 10500 on Avgas - so I really do dispute anyones statement that the Ignitech is only good for road use as its not " powerfull " enough.
The Crane coil with paired outputs was developed for 125cc offshore hydro use , running 20:1 compression on Methanol at 14000 rpm , a really extreme case.
out of interst as i know you have a scope Wob, how long does the spark actually last, it must be in a normal 2t nearly still going on past tdc? (at high rpm.)
just idle curiosity as i seem to recall one of the Rd's (lc i think had a wasted spark)

[Flettner]

Clearly you need a twin cylinder with one each way. . . . If you are heading East.

Send your money to. .

Seems Kels from RK tech lurks here. Gave me a telling off for calling his head the 'potato chip' head, on another forum. Ive invited him over to give us a presentation on his head design. I did warn him to be prepared for a debate but Im sure he knows that.

[F5 Dave]

Thanks for the replys.

Wobbly, I actually have a toroid drawing for my heads that you drew for me a few months back. I plan on having my friend CNC it when the machine is free. ( NEVER )

OCT, Interesting. That seems like a nice method. I would be interested in any additional info you can dig up. Much appreciated.

I just ground some curved tools.

[speedpro]

I was given some bar with tool steel welded to it and ground. There'll be people reading this throwing their hands up in despair but it worked pretty good. Very hard to stop chatter in the lathe but I finished it with a bit of sandpaper. Nowadays I might still do it with the same tool but I would profile the tool steel part in a CNC to get the exact right curve to cut the chamber I wanted. My mate Kev machined a piece of carbide the other day using a CBN endmill I think, so machining tool steel is easy in comparison. It wouldn't be hard to get proper rake and backcut etc.

[flyonly]

In all the RD/TZ and YPVS/Banshee race bike engines I have built - probably 20 in total, I have used DC DC CDI P2 into cheap knock off Ebay , Aprilia RS125/250 coils ( never had a failure )
This draws about 1.5 amps per cylinder into the ECU, and the most powerfull was a Banshee based CPI 400 engine in a Pre 82 Post Classic road race bike with 96 RWHp at 11,000 rpm.
That bike won the Sheene Post Classic TT champs, and broke the lap record by 2 seconds.
All the bikes used CR250 DC type stators that gave 14.2 battery charging voltage ECU input. Using R7376 plugs I have never once had a problem with ignition related power loss.

I tried a DC DC CDI P4 with the paired outputs paralled into the the two same coils on a 82 RWHP TZ twin, this gave exactly the same power on the dyno. - proving to me that ignition milli joule supply was not a limiting
factor in that case at all.
And a TM KZC big bore 152cc that made over 62 Sprocket Hp @ 13800 rpm on pump gas - no spark breakdown issues there either.
Recently I tried , simply out of interest , swapping The Ignitech P2 on the Banshee 400 CPI bike , for a Zeel VPCD20 - programmed exactly the same it gave 2 Hp less but on a different dyno , so good enough for me but also
alot more expensive .The hand held programmer box with no laptop to drag about is a real help at the track though , so I would choose that if the customer was happy to pay for the convenience.

Also a KTM250 road race engine making 70 RWHp at 10500 on Avgas - so I really do dispute anyones statement that the Ignitech is only good for road use as its not " powerfull " enough.
The Crane coil with paired outputs was developed for 125cc offshore hydro use , running 20:1 compression on Methanol at 14000 rpm , a really extreme case.

So if you were wanting to run methanol on a single cylinder setup. How would you configure it?


Sent from my iPhone using Tapatalk

[lodgernz]

I just ground some curved tools.

Me too ! .

[wobbly]

Flett , I have slung serious shit at RK on another forum as well , as he spouts on about how effective his design is , but not once have we seen a direct back to back dyno sheet with equal
CC and MSV. I seem to remember a snake oil line about it only works as it allows higher com without deto - my reply was why then does a normal toroid chamber make more power in a back to back , and then
makes more power again with higher com and no deto - no answer.

Fly , many years ago when we had what was called 125 National ( MX motors only ) in karting , those motors made high 40 sprocket power on Methanol.
Thus the bmep was similar to what we have now in KZ2 on pump gas ( just on 50 Hp ) - and as I said before the 152cc KZ2 engine was over 60 Hp @13800 rpm on a single DC DC CDI
I used a single cdi in a DC DC CDI P2 as at that stage the P1 didnt have a PV servo controller and I had no idea about paralleling outputs back then.
That setup worked just fine with the cheap Ebay Aprilia RS125/250 coil and R7376 -11 plug on 17:1 compression.

Using twin paralleled CDI and a very low primary resistance coil with very high inductance , only became necessary with super high com and super rich Methanol mixtures.
I suggested that to TZE for his Aircooled engine as running high com with very rich Methanol mixtures virtually eliminates the heat soak power loss issue , and allows way more power
from the flawed thermal efficiency of aircooling compared to the same spec in a water cooled engine.

EDIT - forgot the burn period of the Crane coil - it increased from around 50uS to near 150uS

[Myron]

I did several engine/pipe setups for winning Champ 440 engines many years ago , and yes 10500 rpm with a 1000 pipe.
I do remember being told to keep it at 10500 but not why , most likely CVT tuning as you say Condyn.

That was one of the first times I had used the 75% duct exit idea on a customer engine , and when I published the drawing of my pipe setup along
with the reference Jaws pipe , and the dyno result , it created a huge stink.

Even though my pipe made way better power , some people got their panties in a real knot because I had published their medeocre " IP ".
They then swiftly said they now had a better design , but when I challenged them to "show me the money", nothing but silence errupted.

Wow!! Amazing story....

[wobbly]

Yea well Myron I still havnt " seen the money " from that particular stouch.
What would help solve the mystery would be to replicate a shootout that was held even more years ago on a Forum , where the same setup file was used
by all participants in the same software ( Dynamation 2T ).The idea was to see who could design the best pipe for a stock RD250 I think it was.
It went on for months , until someone came up with alot more power , way more than anyone else - impossible numbers in my opinion , even ignoring the fact that fat pipes overscavenge and short circuit.
to hell that a single dimensional code cant account for.
This severely dented my narcisistic ego , till I figured out they were transplanting Methanol into the combustion file instead of 91 pump.

[Myron]

Yea well Myron I still havnt " seen the money " from that particular stouch.
What would help solve the mystery would be to replicate a shootout that was held even more years ago on a Forum , where the same setup file was used
by all participants in the same software ( Dynamation 2T ).The idea was to see who could design the best pipe for a stock RD250 I think it was.
It went on for months , until someone came up with alot more power , way more than anyone else - impossible numbers in my opinion , even ignoring the fact that fat pipes overscavenge and short circuit.
to hell that a single dimensional code cant account for.
This severely dented my narcisistic ego , till I figured out they were transplanting Methanol into the combustion file instead of 91 pump.

I enjoy lurking and perusing all the discussion here, and also enjoy your posts Wobbly. I was disappointed to see this whole thing resurrected from the 10 plus year grave.
Im not sure I know about this "dynomation shootout" to be honest, and thats fine. I have little interest in Sim shootouts which prove zilch.

The whole champ thing should have definitely gone away. To be honest, that whole episode cost a close friendship that had spanned almost a lifetime. It was very unfortunate. It cost someone a sunk livelihood FYI. . About the actual attempt at champ, I admire your attempt. I actually ran a sim on your pipe just to remind myself from so many years ago. I have my opinion on the pipe, but that matters little. I have nothing negative publicly to say about it. There have been several Jaws pipes stamped for champ. At this level, these stamps are tailored to individual bore/stroke ect. settups. To call this one stamp as mediocre is somewhat naive. It is by no stretch mediocre. It has won its share on the track. Your claim of your pipe exceeding the previous best was in sim only. Your comment of 30 or whatever more hp at 11 grand is again not useful to the application. Cvt efficiency wont allow it. Smooth left side curve with a spread of torque/hp is much more valued than huge overrev. To spend a day at Jaws and observe the amount of pipes being produced, and further, to pick the brain of Greg would leave anyone very inspired. The dyno room itself with twin eddy current dynos is intoxicating.

Two other observations if I may. As far as sims, I have a pile of them, I love Vanniks and would highly recommend to anyone. I wore my keyboard out on Dynomation years ago. That was after wearing out another keyboard using a custom program. I will say this about the "outdated" dynomation, if used correctly, I'm not at all afraid to design a full mod pipe for most any application from 70cc to 600 plus cc per cylinder, roll it, and head straight to the dyno with high expectations.

Second observation as regards heads et al. I know its fashionable to unload on RK, I'm not about to defend him, thats his job and prerogative. I will only say that a race head really becomes very application specific. To simply dismiss a certain design ect for all race motors is not warranted imo. Thats all. I will sit back and continue enjoying the discussion as it continues.

[Condyn]

Myron, why sit back when you can aid in development with your experiences. I am a newbie to two strokes and would love to hear your knowledge with snowmobile engine and pipe design. I have built many pipes for my Yamaha GPX and have been getting onto something good as of late. Tested my pipes once on an eddy current dyno and synced the dyno results to simulation results in post2t. Getting very close to my goal in real life and sim as they are now close to one in the same.
At first I put garbage in to the sim I got garbage out.


Myron, were you developing cylinder reed engines or case reed? What were your findings on different pipe designs? Where did the header percentages trend on your champ? I would love to see and hear what you learned.

Last time I will throw stones at rk tek. The reason we all think it is snake oil is the lack of evidence with logical proof of anything. That and the shady webpage that consistently over exaggerates everything in an attempt to shmooze unsavvy buyers with a product that only sells because it has a different appearance. If you are in fact lurking Kelsey, please throw some stones back. I am sure we would all love to get some sense slapped into us. That is all.

[F5 Dave]

The good thing about this thread, if Rob will allow me to speak for him in a legally binding way: is that its intention is to share knowledge. I think that is why it has kept going so long.

Slinging with a couple of exceptions tends to Peter out quickly. Sorry any Peters.

PS a few carriage returns would aid ability to read a clump of text, much appreciated.

[wobbly]

Good on ya Myron for making your enlightening post.

Gotta remember as you point out though that was 10 years ago , and when I made the error of generating shit tons of power at the wrong overev rpm it was simply me showing off ,
and with a major ignorance of the application requirements at the time.
This was quickly pointed out to me , and the fix was easy implemented and then dyno proven, but very non public after the first shit fight that occurred.

But you have an inherent flaw in your comments I must point out - the pipe I designed and then published the back to back result of , against a reverse engineered Jaws effort was shown in a sim result ,
and you imply a distain of that sim only result as being an unreliable proof of superiority.
You then go on to say you have no problem using that sim to regularily design and then produce superior dyno results directly - surely cant be both can it.

I spent years ( like you ) using and working with , and on the hundreds of code changes needed for Dynomation with the owner, whom I met before he started HotRods.
But Neels code has been for a long time now , also after years of refinement , light years ahead in being able to a: replicate a dyno result and b: accurately predict the result of tiny changes in an engines specification.
As as always though , with this level of computational accuracy - but a single dimensional codes inherent limitations , even a tiny bullshit input in = an even greater bullshit output.

And I fully suport TZE's original brave intent , as its something I really believe in , is passing on our 2T knowledge as much as possible - including the fuckups.
TZE gets really pissed with people as he puts it , happily eating at the dinner table but contributing nothing.

[OopsClunkThud]

cutting hemispheres on a knee mill

the best way i can come up with to visualize why this process works is to think of taking a large glass and placing the open end on a globe and note that the rim of the glass is in contact with the globe at all points. If the rim of the glass is the cutting tip of the tool and the globe is rotated, then it will cut the surface of the globe.

If the edge of the cutter touches the axis of the hemisphere then the cut is controlled by a combination of the radius of the cutter and the angle of the spindle. CAD makes quick work of fixing one and calculating the other.

349859
Here we are cutting the squish with a 1.25" end mill and using the CAD to tell us the angle needed is 5.0°.

349860
Here we are cutting a hemispherical combustion chamber, fixing the spindle at 45° and adjusting a boring bar to the needed 28.3mm diameter.

349862
After setting the angle of the spindle and the diameter of the cutter, the rotary table is positioned so that the lowest pass of the cutter is on center with the work in the rotary table. Once aligned the knee can be raised or lowered to control the depth of cut but everything else should be held in position.

[TZ350]

Good on ya Myron.

I fully suport TZE's original brave intent , as its something I really believe in , is passing on our 2T knowledge as much as possible - including the fuckups.
TZE gets really pissed with people as he puts it , happily eating at the dinner table but contributing nothing.

Totally true, here to share tips and tricks and whatever adventures we are up too while celebrating each others efforts, ............ :niceone:

349864

[Condyn]

Re knee mill cutting. Thank you for the extra details. Very nice way to visualize it.

[Myron]

Thanks for reply wob

[Flettner]

cutting hemispheres on a knee mill

the best way i can come up with to visualize why this process works is to think of taking a large glass and placing the open end on a globe and note that the rim of the glass is in contact with the globe at all points. If the rim of the glass is the cutting tip of the tool and the globe is rotated, then it will cut the surface of the globe.

If the edge of the cutter touches the axis of the hemisphere then the cut is controlled by a combination of the radius of the cutter and the angle of the spindle. CAD makes quick work of fixing one and calculating the other.

349859
Here we are cutting the squish with a 1.25" end mill and using the CAD to tell us the angle needed is 5.0°.

349860
Here we are cutting a hemispherical combustion chamber, fixing the spindle at 45° and adjusting a boring bar to the needed 28.3mm diameter.

349862
After setting the angle of the spindle and the diameter of the cutter, the rotary table is positioned so that the lowest pass of the cutter is on center with the work in the rotary table. Once aligned the knee can be raised or lowered to control the depth of cut but everything else should be held in position.

Spooky, just what Ive been doing.

[Flettner]

Steel pistons? Or a screw together composite piston? How well does steel wear against Nikasil? Should a steel piston be hard chromed and ground after? Or Nitrided?
This is what keeps me up at night.
With CNC it could be machined out to a similar weight as aluminium, certainly similar as a forged alloy piston.

[Muhr]

cutting hemispheres on a knee mill

the best way i can come up with to visualize why this process works is to think of taking a large glass and placing the open end on a globe and note that the rim of the glass is in contact with the globe at all points. If the rim of the glass is the cutting tip of the tool and the globe is rotated, then it will cut the surface of the globe.

If the edge of the cutter touches the axis of the hemisphere then the cut is controlled by a combination of the radius of the cutter and the angle of the spindle. CAD makes quick work of fixing one and calculating the other.

349859
Here we are cutting the squish with a 1.25" end mill and using the CAD to tell us the angle needed is 5.0°.

349860
Here we are cutting a hemispherical combustion chamber, fixing the spindle at 45° and adjusting a boring bar to the needed 28.3mm diameter.

349862
After setting the angle of the spindle and the diameter of the cutter, the rotary table is positioned so that the lowest pass of the cutter is on center with the work in the rotary table. Once aligned the knee can be raised or lowered to control the depth of cut but everything else should be held in position.


For those who do not have the tools to do so, it should be possible to transfer the desired shape to a piece of HSS and just dive into the head in a lathe

Or https://vimeo.com/638106094

[F5 Dave]

Can you put some concentric ridges in there? Or perhaps some 4 leaf clover indentations? :sunny:

[wobbly]

Why concentric ridges , they could be a continuous thread form - this would generate chamber swirl just like a 4T port. Could be Rh/Lh for above and below the equator, or clock/anticlockwise tracks.

[Grumph]

Steel pistons? Or a screw together composite piston? How well does steel wear against Nikasil? Should a steel piston be hard chromed and ground after? Or Nitrided?
This is what keeps me up at night.
With CNC it could be machined out to a similar weight as aluminium, certainly similar as a forged alloy piston.


Didn't Frits post a pic of a Ducati piston some time back which was a beautifully delicate steel piece ? Memory says that in those bore sizes and RPM the strength/weight calculation favoured steel

I'd suspect that a coating of something like tin - or flash plated aluminium - would work well enough in nicasil.

I recommend a warm drink at night for you Neil. And of course dreams which feature working schematics of uniflow engines.....

[Flettner]

Yes, the uniflow exhaust piston gets a thermal hiding.

[husaberg]

Didn't Frits post a pic of a Ducati piston some time back which was a beautifully delicate steel piece ? Memory says that in those bore sizes and RPM the strength/weight calculation favoured steel

I'd suspect that a coating of something like tin - or flash plated aluminium - would work well enough in nicasil.

I recommend a warm drink at night for you Neil. And of course dreams which feature working schematics of uniflow engines.....

https://www.cycleworld.com/2016/01/14/steel-pistons-part-1-is-steel-a-better-material-cycle-world-motorcycle-technology-feature/
https://www.cycleworld.com/resizer/iOZPgQ9ij0V61vqA0iY_HhfHG_c=/590x285/smart/cloudfront-us-east-1.images.arcpublishing.com/octane/SPZ7GUVJYFEOLDGM3U7RTOGQFE.jpghttps://www.cycleworld.com/resizer/EA8VyplHgTuSVDV0_dVK3oBzEfA=/590x417/smart/cloudfront-us-east-1.images.arcpublishing.com/octane/UJR3XT6CU5H2LJ7IC67OQYWZ7Y.jpg
https://www.cycleworld.com/resizer/jkBgiBFifFlr_CKhvATaOVGblKE=/590x415/smart/cloudfront-us-east-1.images.arcpublishing.com/octane/TAZKWUS6V5AXNAPSFG35RNB64Y.jpg
https://www.cycleworld.com/resizer/Yv2aS1u5jm7akF_4m1T-buhlrGI=/590x538/smart/cloudfront-us-east-1.images.arcpublishing.com/octane/CALPYL7VSZFZTK3NKHOBZQREYE.jpg
https://www.cycleworld.com/resizer/wo9GKCGQQ5mybvS364dZVSfw-pk=/1440x0/smart/cloudfront-us-east-1.images.arcpublishing.com/octane/VLCGX5PY6NGMXLTYH4IZV4PJMU.jpg

https://www.cycleworld.com/resizer/GRD28c98xq2OD-IEHL6f0uZ56Xs=/754x509/smart/cloudfront-us-east-1.images.arcpublishing.com/octane/KNYSCGLFNVA43EWZP2MJSBPMEM.jpg

[wobbly]

Kentastic had designed something very similar ( in aluminium ) for KZ2 some time ago , sadly having a business that makes money is strangely more important.
Cant believe how cool that tiny small end pin is.

[Norman]

Steel pistons? Or a screw together composite piston? How well does steel wear against Nikasil? Should a steel piston be hard chromed and ground after? Or Nitrided?
This is what keeps me up at night.
With CNC it could be machined out to a similar weight as aluminium, certainly similar as a forged alloy piston.

Here is a link to a sae pre-view for a two stroke steel aluminium hybrid piston

https://www.sae.org/publications/technical-papers/content/2019-32-0508/preview/

[Suzuki nut]

Yes Niels, I do have pictures of the 50cc triple and a lot of other Suzuki racers, about 200 in total. But it is rather impractical for me to post them one by one.
I would gladly ZIP the whole lot but I forgot how to upload zipfiles to Kiwibiker. Anybody?

Do you have any photos of the Suzuki RK67? I am after a photo of the underside, which shows all the cooling fins

[OopsClunkThud]

Can you put some concentric ridges in there? Or perhaps some 4 leaf clover indentations? :sunny:

The lettering in the squish area balances the heat between the exhaust and transfers, and the 4 leaf clover combustion chamber creates counter rotating vortices eliminating the gyroscopic effects...

349906

[F5 Dave]

Aie, may T luck of T Irish be wit ya. :laugh: