ESE's works engine tuner

[Maxdelta]

What was that original pic Max? Not an RM250 as obviously oil injection. So guessing RG250. 1/2 Reed barrel so you don't need monster inlet area and you can get heaps normally. I'd concentrate on anything else.

Like re-engineering the crank to use better rods if you want to rev it a bit more.


Dave,
Its a Suzuki snow cylinder (Arctic Cat 580).

[Maxdelta]

Thanks Wob,
This cylinder has the C ports ducts that are fed right along the outside of the intake port, so there is minimal meat there to widen the port. Also, no room left to lower or raise the port. Hence my looking into the possibility of removing the bridge. The stock bridged intake port width is ~68% of bore. Maybe there's not much left that can be done to this port? I could square off the bottom corners to gain some more area, and I can widen approx. 1mm per side.

356886356887

[wobbly]

Depends on how the intake STA sits in comparison the the Blowdown , and the amount you would gain by increasing the Intake duration ( cut the skirt ) - against loosing bottom end.
Use JanBros spread sheet and analyze the ports.

[katinas]

.
356885

An interview with Dane Rowe, a hottie from the 60's

https://rocinantemecanico.blogspot.com/2012/04/surprise-guest-my-interview-with-dane.html

Great interview.

Thanks

[Frits Overmars]

An interview with Dane Rowe, a hottie from the 60's
https://rocinantemecanico.blogspot.com/2012/04/surprise-guest-my-interview-with-dane.htmlI always admired Dane Rowe and I enjoyed the interview but if I'm not mistaken your picture does not show Dane Rowe but Dutch sidecar passenger Anneke Mak.

[Maxdelta]

Depends on how the intake STA sits in comparison the the Blowdown , and the amount you would gain by increasing the Intake duration ( cut the skirt ) - against loosing bottom end.
Use JanBros spread sheet and analyze the ports.

I'm using Engmod. Basically i can't get enough intake STA. Blowdown and transfers are at ~120hp each. Intake is ~80hp. If removing the bridge isn't an option, then it seems my options are to square off the bottom corner radii and cut the piston skirt. Which leads me to ask....what's a reasonable amount you can remove from the skirt? Would 2.5-3mm be asking for trouble? Thanks for all the assistance.

[katinas]

I'm using Engmod. Basically i can't get enough intake STA. Blowdown and transfers are at ~120hp each. Intake is ~80hp. If removing the bridge isn't an option, then it seems my options are to square off the bottom corner radii and cut the piston skirt. Which leads me to ask....what's a reasonable amount you can remove from the skirt? Would 2.5-3mm be asking for trouble? Thanks for all the assistance.

I remember there was always a dilemma with piston ported engine intake, where to go from std, cut the piston or lowered intake port bottom or just lift the roof. But in any case dont remove the bridge as Wobb advised.
My last experience with piston ported engine was in 1998 with 340 cc single cylinder engine for road race with wide bridge, served as a C channel.
Best final results was nearly std intake ports roofs and bottoms just widened, but huge piston skirt cut ( step by step 3mm then 6 mm and finally 10mm).
I cant remember accurate duration aprox 190. Main advantage over port grinding ( bottom and roof) is that the piston skirt remains hidden from the suction flow for a longer period of time (similar to disc valve long cut).
And bridged port not only save engine, but allows you to make the bottom edges sharp, which, together with piston inside intake skirt sharp edge resist for reverse flow better.

[wobbly]

If you are using EngMod then its real easy to see the effect of cutting the skirt on bottom end power as you approach equality in STA with the Blowdown.
You can also adjust the intake length to see if power can be gained by increasing the air column and thus ram into the open port.

[JanBros]

Use JanBros spread sheet and analyze the ports.

sadly, there is nothing in it for the intake to analise. reedvalve only.

[wobbly]

Sorry JanBros , didnt realize.
But further on the intake scenario , the old TZ350 responded real well to cutting the skirt around 2mm and lengthening the tract 20mm with a plastic spacer from the 250 model.
And how close to the ring is the port top at BDC - can you ditch the bottom ring and grind that much upward - depends upon the skirt length a TDC.

[Peljhan]

I am wondering. If we have an engine with matching STAs let's say 30hp for each system (intake, transfers and exhaust) and we measure 30hp on a dyno.
Than we make-increase STA on one of the systems to 40hp. What would we measure teoretically?

[wobbly]

As long as everything in your sim is capable of achieving the 30 Hp of the STA prediction, depending upon the inertia of the vehicle components and the friction component, then you
will measure something like 14% less on a rear wheel Dynojet = 25.8RWHP.
EngMod calculates crank power - so if you now upgrade every part of the engine ( not just change the ports ) then the same applies to the new prediction.
Note the Exhaust STA is pretty much irrelevant ( except when using the duct exit radio button shortcut ), its the Blowdown that is highly important.

[katinas]

Sliding pipes from eighties. I just wonder when they really started using it.

From 21:21- https://youtu.be/2RZ86QoA-qI?si=ZuxwBLNCCw_762ih

From 0:35 https://youtu.be/D1e_vKt8Va0?si=lATwZp9HRV_D4QAw

[Jonny snatchsniffer]

I know most of you on here dont like air cooled 2 strokes because of thermal limitations, but i have what i have, its a 200cc lambretta piston ported no reed, the intake is only 153.5, exhaust angle 180, a and b transfers at 120, boost port 122.5, now im using a pipe from the 80's which has a long parallel header, also a 28mm pwk, the inlet is bridged, tz350, you probly know about the ported stuff, tho saying that most of us have been there done that, but my thing is Italian shopping bikes, and wobbly, when you worked with Jim did you do any of the scooter, like the jl3, jl4 lambretta pipes? And could they be improved upon?
I dont have engine mod and just threw it together with the above timings and thrashed the fuck out of it 140M to a rally but runs out of puff at 8000rpm @76mph gps
I know its over 60 yrs old but I'd like get more out of it
My 125 1966 vespa has 27 rwhp so surely I can get more out of a 200, thi over square at 58x66
So what should I be doing in my man cave to get it singing a bit more? I'm also stud limited and single chef hat exhaust port

[wobbly]

The scooter pipe thing happened after I left JL.

[Gradella23]

The scooter pipe thing happened after I left JL.

hello Wob, any sneak peek on the newcoming Kz R3? I saw Franco joined LKE, i was quite shocked

[Wos]

I know most of you on here dont like air cooled 2 strokes because of thermal limitations, but i have what i have, its a 200cc lambretta piston ported no reed, the intake is only 153.5, exhaust angle 180, a and b transfers at 120, boost port 122.5, now im using a pipe from the 80's which has a long parallel header, also a 28mm pwk, the inlet is bridged, tz350, you probly know about the ported stuff, tho saying that most of us have been there done that, but my thing is Italian shopping bikes, and wobbly, when you worked with Jim did you do any of the scooter, like the jl3, jl4 lambretta pipes? And could they be improved upon?
I dont have engine mod and just threw it together with the above timings and thrashed the fuck out of it 140M to a rally but runs out of puff at 8000rpm @76mph gps
I know its over 60 yrs old but I'd like get more out of it
My 125 1966 vespa has 27 rwhp so surely I can get more out of a 200, thi over square at 58x66
So what should I be doing in my man cave to get it singing a bit more? I'm also stud limited and single chef hat exhaust port

In germany there is a very good old scooter specific forum called german scooter forum (gsf)

If you ask your questions there even in english i am pretty sure you find specific help:2thumbsup

But its always worth to stay here, listen what others do in the big 2 stroke world ;)

https://www.germanscooterforum.de/

Grüße Wolfgang

[wobbly]

Grad, the R3 pipe /manifold/porting changes I worked on for a couple of months were sent of to Franko several months before the World Cup.
I heard nothing back - very unusual, then I received an email from the Flenghi brothers the day after the Cup finished, saying he was no longer at TM.
I got several spies on the job and found out he had gone to Lenzo.

Still no word from him at all - except a small pic of the new LKE Rev1 homologation stamp on Instagram.
He's now working in Mafia land big time, so should be very careful.
He has been beaten by independent tuners for some time now - maybe that is the root cause.

TM want me to sign an NDA , but I still have not seen any results from my new manifold or pipe testing.
They have agreed to pay me, thats some consolation, but being treated like a leper doesnt go down well - they simply ignor any conversation about what happened with Franco or the tests.
I do wonder if I designed the LKE pipe and didnt even know i did it.

[Flettner]

Grad, the R3 pipe /manifold/porting changes I worked on for a couple of months were sent of to Franko several months before the World Cup.
I heard nothing back - very unusual, then I received an email from the Flenghi brothers the day after the Cup finished, saying he was no longer at TM.
I got several spies on the job and found out he had gone to Lenzo.

Still no word from him at all - except a small pic of the new LKE Rev1 homologation stamp on Instagram.
He's now working in Mafia land big time, so should be very careful.
He has been beaten by independent tuners for some time now - maybe that is the root cause.

TM want me to sign an NDA , but I still have not seen any results from my new manifold or pipe testing.
They have agreed to pay me, thats some consolation, but being treated like a leper doesnt go down well - they simply ignor any conversation about what happened with Franco or the tests.
I do wonder if I designed the LKE pipe and didnt even know i did it.

Welcome to the club, at least you are getting paid.

[Frits Overmars]

... I received an email from the Flenghi brothers the day after the Cup finished, saying he was no longer at TM.
I got several spies on the job and found out he had gone to Lenzo. He's now working in Mafia land big time, so should be very careful.
I do wonder if I designed the LKE pipe and didnt even know i did it.Been there, know the feeling. About 20 years ago my friend Roland Holzner, after designing the Maxter kart engine, got an offer he couldn't refuse from Lenzo. He flew me in as well. When things got less pleasant, Roland's laptop, with my software on it, was stolen from his apartment. When he tried to rapport the theft to the local police, he was told that he couldn't, because he was not the rightful tenant of that apartment. He was shown a document stating that the apartment was rented out to Lenzo. The ink on that document was still wet and why would Lenzo rent an apartment that he already owned?
During this episode I had a whole hotel in the village of Brolo, Sicily (where Franco Drudi is staying now) to myself, owned by Lenzo and occupied by just me, the hotel staff and the biggest cockroaches you ever saw.

In case you're interested in the technical side of things, we worked on a cylinder that may look kinda familiar now. But at the time the local experts told us that it could never work because the auxiliary exhaust ports were twice as large as they had ever tested. And there was also a hump in the exhaust duct floor that 'confused the flow'.
Nice detail in the picture below: notice the broken-off M6 tap, top left. Just think what could have happened if the machine saw blade had hit that tap a little more head-on...
Anyway it paints a nice picture of the work quality.
356895

[Storbeck]

Been there, know the feeling. About 20 years ago my friend Roland Holzner, after designing the Maxter kart engine, got an offer he couldn't refuse from Lenzo. He flew me in as well. When things got less pleasant, Roland's laptop, with my software on it, was stolen from his apartment. When he tried to rapport the theft to the local police, he was told that he couldn't, because he was not the rightful tenant of that apartment. He was shown a document stating that the apartment was rented out to Lenzo. The ink on that document was still wet and why would Lenzo rent an apartment that he already owned?
During this episode I had a whole hotel in the village of Brolo, Sicily (where Franco Drudi is staying now) to myself, owned by Lenzo and occupied by just me, the hotel staff and the biggest cockroaches you ever saw.

In case you're interested in the technical side of things, we worked on a cylinder that may look kinda familiar now. But at the time the local experts told us that it could never work because the auxiliary exhaust ports were twice as large as they had ever tested. And there was also a hump in the exhaust duct floor that 'confused the flow'.
Nice detail in the picture below: notice the broken-off M6 tap, top left. Just think what could have happened if the machine saw blade had hit that tap a little more head-on...
Anyway it paints a nice picture of the work quality.
356895


Bit of a tangent, but your comment about being told that the large auxiliary exhaust ports were too large reminds me of a thing I've long wondered about. I've seen several examples of cylinders with super tiny auxiliary exhaust ports. Always wondered why on earth they would bother to add auxiliary ports and then make them so small. My assumption is that there is something that can be done "wrong" with auxiliaries to make them have negative affects, the designers of those cylinders unknowingly did that, and ended up testing smaller and smaller auxiliaries until that negative affect went away. But I have no idea.

[Frits Overmars]

... your comment about being told that the large auxiliary exhaust ports were too large reminds me of a thing I've long wondered about. I've seen several examples of cylinders with super tiny auxiliary exhaust ports. Always wondered why on earth they would bother to add auxiliary ports and then make them so small...In the beginning (let's give this a biblical twist) there were no auxiliary exhaust ports. Then Jan Thiel changed history, and others began to copy him, drilling small channels while trying to avoid the cylinder studs and the cooling system. Those local experts in Brolo, Sicily had never even tried decently-sized aux ports. They just went by what they had seen until then and from that they 'knew' that ours were too large.

You can go wrong with large auxiliary ports. Piercing the cooling system is not good practice and neither is combining effective aux ports with directionally unstable scavenging, or with piston skirts that open the aux ports around TDC. Smaller aux ports can avoid such problems but that's not the best solution if you want to make a powerful engine.

[wobbly]

Having not had any response from my many attempts to contact Franco , and receiving no feedback from the Flenghi brothers Filippo /Thomas I contacted a friend
Marc Marcelet.

He is also a very good friend of Roland and he has asked him to contact Filippo in person ( in Italian as he speaks little English ).
They have agreed to fulfil my normal " contract " for the R3 development work, but I fear I have been " tarred with the same brush as Franco " and am now PNG.

Really pisses me off, having started working with Claudio well over a decade ago and I have turned down work from others feeling loyalty to TM with such a long association.
We shall see what Roland can find out - I know he worked at TM, but Franco never had a kind word to say - nothing unusual about that though.

The latest info is that Franco was fired as he was spending all his time trying to get his own KZ engine homologated, ran out of time, and the Lenzo thing is just a stop gap.

[diesel pig]

When I read my copy of Jan Thiel's Book he hinted it was hard to work with the Italilans. But I now understand he was playing it down.

[Jonny snatchsniffer]

In germany there is a very good old scooter specific forum called german scooter forum (gsf)

If you ask your questions there even in english i am pretty sure you find specific help:2thumbsup

But its always worth to stay here, listen what others do in the big 2 stroke world ;)

https://www.germanscooterforum.de/

Grüße Wolfgang

I've been on gsf but translate is shite, mathias scherer use tovmake me pipes for the vespa, also having read all of the rsa thread, and all of this thread which after all is about buckets and, started by tz30 to explore the limitations and from getting to 30hp from his air cooled bucket
I intend to do the same but from something even older, as its a 2 stroke no matter my starting point surely all the rule apply, ask a simple question on say port roof angles or things like that, you get on the uk forums at least, the ones that dont know talk shit and the ones who do won't say, for example on 2 uk sites its been advised that the piston at bdc is ok at 2mm above the floor but dont ever have it lower, on here ideas are floated freely, (shame on ktm)
However having read all this, my memory is shit and forgotten 99% of it, its not big at 198cc but bigger than the 50s

[husaberg]

I am almost feeling guilty about bringing this up, as they are Italian.

But I am looking for a not so common Brembo caliper for a pre-89 project.

I know I can buy a new repo or get one close enough like a ktm60/65, but as I am in pretty deep now and a bit of an anorak.

As best as i can discover they were oem on a few bikes of the late 80s and early nineties they are a Brembo calipers As used on the TY250, Aprilia Climber, Montesa Cota, and I think a few others, like I possibly husky al ktm Gas Gas .and Fantic.


DR50 Big.

Grimeca and AJP later made a similar one used on a lot of debris, like the Senda and the early ubiquitous early 98 to 01 KTM 60/65. Which if i can't find a cheap one ,is what i will have to use.

Anyone have a lead on one or know other bikes that have them? i found a few but Shipping on eBay from the EU or US is almost criminal or the sellers dont want to?
I tried the usual cross matching through pads etc but they used similar pads on other Brembo and Grimecas?

They look very similar to a Yamaha RD350 caliper only smaller and not cast iron the Yamaha ones which i always thought was a licensed Lockheed Copy?
The Brembo also have square pads.

pic to be attached if KB lets me.
356896356897

[ranasada]

Having not had any response from my many attempts to contact Franco , and receiving no feedback from the Flenghi brothers Filippo /Thomas I contacted a friend
Marc Marcelet.

He is also a very good friend of Roland and he has asked him to contact Filippo in person ( in Italian as he speaks little English ).
They have agreed to fulfil my normal " contract " for the R3 development work, but I fear I have been " tarred with the same brush as Franco " and am now PNG.

Really pisses me off, having started working with Claudio well over a decade ago and I have turned down work from others feeling loyalty to TM with such a long association.
We shall see what Roland can find out - I know he worked at TM, but Franco never had a kind word to say - nothing unusual about that though.

The latest info is that Franco was fired as he was spending all his time trying to get his own KZ engine homologated, ran out of time, and the Lenzo thing is just a stop gap.


did you know that TM was sold to a fund, the same one that owns the OTK group (tonykart/vortex) & vegatyres?

[wobbly]

Several people with Tinfoil hats have said its a "Mafia " fund - just conjecture I imagine.

[crbbt]

I am wondering if anyone has experienced having a carb needle snap?

On my PWK. I've recently snapped two through a clip slot.

Seems to happen after landing a jump

I am guessing it's either a worn slide or the body.

But before I order another needle and a new slide. thought I would ask

[F5 Dave]

That's some weird shit. I had some debris fall in (trackside jetting) ans it caused the needlejet damage so it would scratch and hang up a needle (ie stick) had to turn up a new insert.
But snap??? That's weird. Genuine PWK not a clone?

[wobbly]

In the Dellorto 30mm carbs I use they have a washer sitting on the clip, and the screw in needle holder has a spring that pushes down on that washer.
Thus the needle can float.
It does of course and that wears the needle parallel and the tube, eventually making the transition and mid go rich.

The cure was to put a washer on both sides of the clip, insert the holder loosely and fit the slide.
Then push the slide up and down a few times and lock the holder.
This clamped the needle in place.

It did two things - eliminated the wear issue, and weirdly it reduced deto, allowing leaner mains and higher EGT.

[Wos]

I am wondering if anyone has experienced having a carb needle snap?

On my PWK. I've recently snapped two through a clip slot.

Seems to happen after landing a jump

I am guessing it's either a worn slide or the body.

But before I order another needle and a new slide. thought I would ask

There are many adtermarked and copy pwk in the universum Needles and clips too.
Some needles are of bronze / cusn with clips that look that they ar made of brass or copper berylium..

CUSN is not very break ressitant...and the brass clips loose tension very quick.

Mayby the clip slots have been worn out before breaking?

Steel clips as in keihin origina dont loose tension and keihin needles have best precision

Grüße Wolfgang

[Frits Overmars]

I am wondering if anyone has experienced having a carb needle snap? On my PWK. I've recently snapped two through a clip slot. Seems to happen after landing a jump. I am guessing it's either a worn slide or the body. But before I order another needle and a new slide. thought I would askA throttle slide tends to tilt slightly backward-forward due to the inlet flow pulsations it is subjected to. And as you guessed, this tilting becomes worse as the slide and/or the carb body become worn out.
In some throttle slide-needle combinations the needle fits so tightly in the slide that it cannot accommodate this tilting. The needle is then subjected to bending stresses and breaks at its weakest point: at one of the notches for the clip. The needle then remains in the throttle closed position while the slide is open, resulting in a lean mixture and a seizure.

You could enlarge the needle bore in the slide, but I'd leave a short piece of the original narrow bore, so the needle is still centered but can swivel just the same.

[crbbt]

Thank you for the replies.

Genuine Keihin, Yamaha needle

I've pulled the carb down. I can't see anything obvious.

The needle in carb in the other CR appears to have the same amount of movement (front, back, side to side)

Nothing money can't fix :rolleyes:

[TZ350]

.
356918 356919

1980 Suzuki GP125. Tried a power jet cut off on the old Suzuki. Used an air solenoid that was triggered at 11,500 rpm to collapse the fuel being drawn up the power jet tube.

Idea worked pretty well, red line. It will be interesting to see if the extra drive is noticeable on the track this weekend.

[ApolloMotoMoto]

Another interesting bit to add...

Attempting to do some further research and I tried to explicitly point google search AI at the kiwibiker.co.nz domain for a directed search and it returned this:

"The search returned no results, likely due to the website being unreachable or inaccessible at this time, as indicated by previous search results suggesting connectivity issues with the domain. I am unable to access the content of the forum to verify if the specific terms you requested are present."

Interesting, no?

[ApolloMotoMoto]

Tried a few different ways to get the google search API to reach Kiwibiker.co.nz, but apparently its innacessable, and apparently there are many other reports of innacessability to this domain from other users.

[bad'rule]

doing good from my part here in Malaysia , they happened to me before, usually it just coverage problems. Especially on school holidays, connection will go very lame or not moving at all.

Sent from my RMX1911 using Tapatalk

[pete376403]

This turned up on my FB feed this morning

[husaberg]

This turned up on my FB feed this morning
maybe Jan will add some translation ans text ad some more pis this is alli have
https://www.kiwibiker.co.nz/forums/album.php?albumid=4944

[JanBros]

maybe Jan will add some translation ans text ad some more pis thisis alli have

I'm a Jan :confused:
there is nothing technicaly interesting in the text, it is what we would call nowadays "clickbait" news : an article based on a photo that tell's you no more than what you can see in the picture.
I presume those days they already had some crowdfunding that raised 16.000 gulden (1 gulden is slightly less than half an euro) and there is some little talk about the successes of 1968-69-70 and the preparation for the next season.
what strikes me the most in the article is that at that time, aparently they didn't have an hydraulic press, for example to rebuilt cranks.

[Frits Overmars]

an article based on a photo that tells you no more than what you can see in the picture.Except: the picture is lying! Jan Thiel never intended to place the exhaust pipe above the engine but he did not want to give anything away at that stage, so for this photo he rotated the cylinder 180°, with the exhaust port on top.

[pete376403]

More from FB. The text accompanying it is obviously AI generated as this engine is described as a 350 twin (so I left that off)

[Peljhan]

I do some manual machining for my projects and I am wondering how were the outer radiuses on engine mounts made on this Jamathi engine?
I have some ideas, but want to know how it was made back in a day?

[wobbly]

Just as easy now as it was back then. The case supported thru the mounting hole in a 3 Jaw on a dividing head set vertically - with a long series cutter machining the whole surface in
several passes.

[husaberg]

Jamathi

https://www.kiwibiker.co.nz/forums/showthread.php/145224-Race-chassis?p=1131025140#post1131025140 (https://www.kiwibiker.co.nz/forums/showthread.php/145224-Race-chassis?p=1131025140#post1131025140)

https://www.elsberg-tuning.dk/jamathi.html

[Flettner]

I do some manual machining for my projects and I am wondering how were the outer radiuses on engine mounts made on this Jamathi engine?
I have some ideas, but want to know how it was made back in a day?

Cast them.

[husaberg]

I do some manual machining for my projects and I am wondering how were the outer radiuses on engine mounts made on this Jamathi engine?
I have some ideas, but want to know how it was made back in a day?


Cast them.

Go all Bert Munro and use a file.
note these conrods
356969356970
later ones were caterpillar axels heated up power hammered into a fillet holes machined and roughed out but then finished with handtools
i think he could knock out one in a weekend.
Early ones were i think from ford truck axles.

[ApolloMotoMoto]

Unintended Post

[ApolloMotoMoto]

I am attempting to track down an ignition coil that may not exist, or may be quite rare.... (or it might be very common but no one really knows what it is...).

I need CDI ignition coils for a project I am working on with ....really low.... inductance values.

I know Wayne uses high(ish) inductane Crane Cams PS91 coils for the 2-into-1 IgniTech DC-CDI setup to pump up the amps driven into the spark kernel.

But, I am playing with a different... expression... of the CDI circuit; and I am tuning for a faster rise time for the first high kV spike that "strikes the arc" (in addition to dumping some decent amps into the damped oscillation "tail"...)

The expression of the circuit I am playing with drives a requirement for ...medium... turns ratio in like the 30-60:1 range and LOW inductance....

Like uH scale primary and mH scale secondary. Anything over 1 Henry on the secondary is useless for my efforts...

IgniTech is one of the only people on the planet that publish inductance numbers with their coils; unfortunately no secondary inductance reported for the IC-CDI-F; but with its 80 uH primary inductance it is in a class of coils that are so rare they might as well not even exist.


Anyone of you know where I can find coil that are in the same "family" as the IgniTech IC-CDI-F, and by that I mean EXTREMELY low inductance?

I am really tring to see if I can find anything confirmed lower inductance than the IC-CDI-F ....anywhere on the planet..... before I go have custom coils wound.

[katinas]

Anyone of you know where I can find coil that are in the same "family" as the IgniTech IC-CDI-F, and by that I mean EXTREMELY low inductance?

I am really tring to see if I can find anything confirmed lower inductance than the IC-CDI-F ....anywhere on the planet..... before I go have custom coils wound.

Honda NS400\250 small type CDI coil MP 02, with primary 0,18 ohm, but secondary 4,1 k ohms.
https://www.ebay.co.uk/itm/183162158215?_skw=honda+ns+400+coil&epid
https://www.ebay.co.uk/itm/177335855786?_trkparms=amclksrc

[TZ350]

.

2Stroke Stuffing. Claims 26 HP on pump gas:- https://youtu.be/bRRIXnkRGwQ?si=mlPz2tbHtQNamVgD

[Sketchy_Racer]

26hp on pump gas is a bold claim! Seriously impressive if verified.

As someone who has built their own dyno, I can make it say what ever I like and you don't know what bullshit other "calculations" the software is doing in the background either. It would be a great move for Alex to take it to a known and respected dyno to verify.

[husaberg]

26hp on pump gas is a bold claim! Seriously impressive if verified.

As someone who has built their own dyno, I can make it say what ever I like and you don't know what bullshit other "calculations" the software is doing in the background either. It would be a great move for Alex to take it to a known and respected dyno to verify.
Seen your latest Video Glen, impressive. post it here to please.

[Sketchy_Racer]

Thanks Husa, link here for those interested.


https://youtu.be/TDSJnMOpniE?si=lUE6hioRmveY-Dxy
(https://youtu.be/TDSJnMOpniE?si=lUE6hioRmveY-Dxy)


I'm looking forward to getting the engine back together and progressing the EFI. The first tests with the acceleration enleanment (think inverted acceleration enrichment table) is showing to be incredibly responsive.

Cheers,
Glen

[SwePatrick]

26hp on pump gas is a bold claim! Seriously impressive if verified.

As someone who has built their own dyno, I can make it say what ever I like and you don't know what bullshit other "calculations" the software is doing in the background either. It would be a great move for Alex to take it to a known and respected dyno to verify.

I have invited him to my dyno, only a minor daytrip away.

[F5 Dave]

Thanks Husa, link here for those interested.


https://youtu.be/TDSJnMOpniE?si=lUE6hioRmveY-Dxy
(https://youtu.be/TDSJnMOpniE?si=lUE6hioRmveY-Dxy)


I'm looking forward to getting the engine back together and progressing the EFI. The first tests with the acceleration enleanment (think inverted acceleration enrichment table) is showing to be incredibly responsive.

Cheers,
Glen
Watching your updates with interest. Be freat to see it when it makes it to the track. Ruapuna short track would be fun.

[TZ350]

26hp on pump gas is a bold claim! Seriously impressive if verified. As someone who has built their own dyno, I can make it say what ever I like and you don't know what bullshit other "calculations" the software is doing in the background either. It would be a great move for Alex to take it to a known and respected dyno to verify.

357038

Here at Team ESE we run a Dynojet.

Richban and Team GPR built their own dyno and wanted to check it against ours by running up Richbans FXR150 on it.

357039357040

I think Richbans FXR was the first 4 Stroke Bucket to crack 25rwhp and they wanted to verify it on a known Dyno.

There are a number of home made dynos around. The impression I got, was that the people who were clever enough to make their own were also clever enough to calibrate them to display real horse power. Doing anything else made no sense.

A metric horsepower is <mark class="HxTRcb" jscontroller="DfH0l" jsuid="Q9E7ub_a" data-processed="true" style="color: rgb(0, 29, 53); border-radius: 4px; background-image: linear-gradient(90deg, rgb(211, 227, 253) 50%, rgba(0, 0, 0, 0) 50%); background-position: 75% 0px; background-size: 200% 100%; background-repeat: no-repeat; background-attachment: scroll; background-origin: padding-box; background-clip: border-box; padding: 0px 2px; animation: 0.75s cubic-bezier(0.05, 0.7, 0.1, 1) 0.25s 1 normal forwards running highlight-animation; font-family: &quot;Google Sans&quot;, Roboto, Arial, sans-serif; font-size: 16px;">the power required to lift a mass of 75 kilograms one meter high in one second</mark>, which is equivalent to approximately 735.5 watts. This is different from the imperial or mechanical horsepower, which is equivalent to about 746 watts. Metric horsepower is also known as a PS (Pferdestärke), CV (cheval-vapeur), or other variations. That basically read much the same as DIN.

[TZ350]

357041 357042

In the pursuit of ever more hp I made a triple exhaust port cylinder. Speedpro helped me with this with some clever milling of the eyebrows.

Initial dyno tests showed a big hole at the rpm where pipe reversion is out of sink. I became suspicious that the cutaways on the side of the Suzuki piston were allowing the pipe to interfere with the crankcase.

357043

So I fitted a Wiseco piston that did not have this problem.

357044

New Wiseco, red line. So, Suzuki piston side cutaways were not the problem?????

Blue line, the old single exhaust port cylinder. Also red and blue lines are offset because runs were inadvertently done in different gears. Blue = 5th, Red = 4th.
Observation, the triple exhaust cylinder ran much better, cleaner at 9,500 rpm than the single. 250cc Kawasaki F81.

Will have more of a look next week. Once I get it sorted, then onto the Nitro injection.

[Peljhan]

Talking about dyno figures, I had a huge issue or let's say dilemma this year when I bought new dyno software.

In my country Slovenia with 2M people there is not many dynos and 2t tuning-racing scene is mostly me and my 10 friends / schoolmates and we all know eachother. Me and 2 other tuners, so 3 different home made inertia dynos used dynomec software from Finland (https://www.dynomec.com/). My roller had 300kg and 4,8kgm^2 of inertia, other two had around 3,5. We were using this software (Dynomec WT and is not for sale anymore) for 15 years now and it was very simple and could not be more basic as it is.

In these 15 years we got out rear wheel horsepower figures like:
- Tomos D6 50cc pistonport 14hp @14200rpm
- 50cc freetech 23hp @16500rpm (also raced in Hockenheim)
- Tomos 50cc classic bike with bidalot50 and rotary intake 18hp @14500rpm
- Tomos 90cc aircooled '77 pistonport stock bike 9hp @6000rpm (same as claimed from factory)
- Stock aprilia RS125 24hp, later tuned to 30hp
- Cagiva Mito 125 '93, tuned to 33hp
- Yamaha 125 4t 2006 9hp :rolleyes:
- Yamaha YZ125 2015 stock 33hp
- Honda RS125 NX4 2003 40hp (two bikes)

So many bikes were measured. We also tested some on both dynos and measurements were the same or like 0,1-0,3hp difference.
Also one of the bikes Honda 250 4t was measured at Akrapovič facility and one of the dynos was checked with that bike (don't ask me about details how measurements were made)

This year I bought new software from DTec (http://dtec.net.au/) as it is major upgrade as EGT, temperatures, data analysis is much better to do, so many options, and price was good.

So I tested one bike and it was measuring 6hp instead of 9hp. Then tested another 3 known bikes and all measurements were lower for a factor of 1.3. I investigated and my old Dynomec had inside some random factor of 1.3 that I was suspicious of since I bought software in 2010.
So I tried to measure power with weight drop, suspended from 3m of height with rope winded around roller and 8x pulley sistem, but measurements were too slow and friction from the rope was not constant (logically) and did not made any conclusions from that.
I also tested electic bike with in wheel motor with nominal power of 1000W, I measured around 850W with new dyno. EM power could be stated-measured on many ways by factory so I also didn't find any answers.

At the end I adjusted inertia, multiplied it by 1.3 and called it a day. Why? So we can communicate with my friends about power we made and what we figured out. I can compare results with my old dyno and customers have bragging rights with same value if they measure at my place or on other dynos. Life is easier that way.

I know dyno is used for comparing between setups, finding small gains etc and hp number is not so important, but still, as an engineer, it doesn't give me piece of mind. And 30% difference is not small. So are all dynos showing too much, all freetech bikes have 18hp instead of 23hp, but how, 18hp was claimed in 1978 by many 50cc like Kreidlers, Tomos etc. Was it all just propaganda?

Any ideas, so I could sleep better?
Does anyone use some of theese softwares, Dynomec and Dtec and has some experience with similar problems?

[Sketchy_Racer]

Any ideas, so I could sleep better?
Does anyone use some of theese softwares, Dynomec and Dtec and has some experience with similar problems?

The dyno I built also uses Dtec and I have had exactly the same experience as you in regards to measured power outputs against calculated MOI.

That is what I was referring to earlier that I am almost certain that most dyno softwares are adding some level of "correction" that is not user adjustable.

Where I am, dynojet is the most popular commercial dyno around. There are two local to me that I have had bikes on and the outputs are similar. When I set up our Dtec dyno, the power numbers were very low, so I did the same as you and adjusted the MOI to get them as close as I could to the dynojet figures so that, whilst not perfect, there was some level of comparability.

[Frits Overmars]

Talking about dyno figures, I had a huge issue or let's say dilemma this year when I bought new dyno software.. all measurements were lower for a factor of 1.3. I investigated and my old Dynomec had inside some random factor of 1.3 that I was suspicious of since I bought software in 2010.
Any ideas, so I could sleep better?Yup. My FOS dyno software has a UNIT-option that offers the choice between Horsepower an KiloWatt. It caused one user to call desperately: "My engines suddenly produce a lot less power !" He had not noticed that somebody had changed his Horsepower-setting into a kiloWatt-setting :D.

[F5 Dave]

. . .

A metric horsepower is <mark class="HxTRcb" jscontroller="DfH0l" jsuid="Q9E7ub_a" data-processed="true" style="color: rgb(0, 29, 53); border-radius: 4px; background-image: linear-gradient(90deg, rgb(211, 227, 253) 50%, rgba(0, 0, 0, 0) 50%); background-position: 75% 0px; background-size: 200% 100%; background-repeat: no-repeat; background-attachment: scroll; background-origin: padding-box; background-clip: border-box; padding: 0px 2px; animation: 0.75s cubic-bezier(0.05, 0.7, 0.1, 1) 0.25s 1 normal forwards running highlight-animation; font-family: &quot;Google Sans&quot;, Roboto, Arial, sans-serif; font-size: 16px;">the power required to lift a mass of 75 kilograms one meter high in one second</mark>,. . .
Talking of Metric, quoting US sources results in spelling mistakes.
A Meter measures something. It is not a unit of length.

'Mericans. Don't use the Metric system, but can't let the opportunity slide to spell things differently to the rest of the world.

[lodgernz]

In the pursuit of ever more hp I made a triple exhaust port cylinder. Speedpro helped me with this with some clever milling of the eyebrows.

Initial dyno tests showed a big hole at the rpm where pipe reversion is out of sink. I became suspicious that the cutaways on the side of the Suzuki piston were allowing the pipe to interfere with the crankcase.



Rob, have you ever tried using the PrtScrn key to capture dyno runs, rather than photographing the screen?

[F5 Dave]

Windows key + Shift + S

Then select the area. Paste

[TZ350]

Talking of Metric, quoting US sources results in spelling mistakes. A Meter measures something. It is not a unit of length.
'Mericans. Don't use the Metric system, but can't let the opportunity slide to spell things differently to the rest of the world.

Left to my own devices the spelling and english would be even worse .....


Rob, have you ever tried using the PrtScrn key to capture dyno runs, rather than photographing the screen?

The dyno computer is an old relic. Not connected to the Internet or company's LAN. I had not thought of taking screenshots with it. The phone was easy, I might try a screen shot next time. Thanks.

[F5 Dave]

I should have known that. I was just wondering how the old dyno was fairing as I can't imagine it is still running Win 3.11.

[Frank S.]

I found out, that the rear wheel inertia has a quite measurable effect on dyno results.
On my homemade dyno I have only a 80kg roller, which is far from optimal,. So I had to use relatively long gearing to compensate.
In this specific case the inertia of the rear wheel has a huge effect on the measurement.
I don't remember exactly, didn'use it for years, but I had to add a big amount to the roller inertia.

[Frits Overmars]

I found out, that the rear wheel inertia has a quite measurable effect on dyno results. On my homemade dyno I have only a 80kg roller, which is far from optimal,. So I had to use relatively long gearing to compensate. In this specific case the inertia of the rear wheel has a huge effect on the measurement. I don't remember exactly, didn't use it for years, but I had to add a big amount to the roller inertia.It's not so much the rear wheel inertia that is to blame, but the ratio between rear wheel inertia and roller inertia, and that ratio won't change if you alter the gearing.
Increasing the roller inertia, as you did, is the only effective action.

[JanBros]

I think he had to use a very long gearring so that the pull would last long enough. if from low to max rpm lasts only 2 seconds, you have less points for an accurate graph and the engine/pipe won't reach the temperatures it would reach on the track.

[crbbt]

Hello Brains trust,

I am wondering if anyone can advise me on removing the powerjet tube that protrudes into carb bore?

specifically on a keihin spj.

The issue I have is that the tube's outlet/discharge is facing away from the carb slide and need to be rotated 180.

I am assuming they are a press fit but do not want to destroy the tubes or the carbs

Thank you!

[Peljhan]

That is what I was referring to earlier that I am almost certain that most dyno softwares are adding some level of "correction" that is not user adjustable.

Where I am, dynojet is the most popular commercial dyno around. There are two local to me that I have had bikes on and the outputs are similar. When I set up our Dtec dyno, the power numbers were very low, so I did the same as you and adjusted the MOI to get them as close as I could to the dynojet figures so that, whilst not perfect, there was some level of comparability.

I think Wobbly stated that DynoJet overcorrects for 15%
Do you know how much did you adjust the MOI from what it actually is?

Darren from Dtec said, their software is made on known basic equations and no additional factors are used.
Dynomec had some correction inside that was 1.30, exactly the difference with Dtec.

I also saw written on VHM page for their dyno tests:
- We measure on the rear wheel, but add a small correction factor (0.05PK/Kmh) for the crankshaft. So the graphs in the video's show the power on the crank.
What junk of correction is that? And definetly not small. For 50cc measured from 30-120km/h that is 1,5hp at bottom and 6hp at overrev. So for weak bikes it can double the power and for 1000cc bike is like nothing.

Thanks for suggestion Frits, but that was not the case as you can change from imperial to metric in the software. Downside is I can't choose HP/Nm/°C, only HP/lbsft/°F or kW/Nm/°C because we all speak in HP figures between friends.

[TZ350]

I am almost certain that most dyno softwares are adding some level of "correction" Where I am, dynojet is the most popular commercial dyno around.

It looks to me, that DynoJet's are a little bit optimistic but seem to give consistent results between individual units.

[F5 Dave]

At some point the horse(sorry) has bolted and something is so ingrained that we have to keep using it.
Dieters count in calories but really mean kilocalories and joules aren't in any conversation. Our wheels an TVs are inches. Although there was a Citroën that had metric wheels decades back apparently.
So I'm a wild hypocrite fervently defending the metric system and English language from being Americanised. But accepting some things like hp are probably best left fairly constant. It was bad enough with quoted hp being believed. Journalists are usually aware of this now, but still like waffling on about torque as if some mysterious motive force that is somehow produced independently and not mathematically constrained.
Anyway, rant for lunchtime. :rolleyes:

[Frits Overmars]

It looks to me, that DynoJet's are a little bit optimistic but seem to give consistent results between individual units.I once hooked my software onto the Dynojet of nearby Ten Kate (superbike world champ at the time), so each run on the Dynojet was simultaneously monitored by Dynojet software and FOS software. Clear outcome after a series of runs: when a bike delivers 100 hp on the dynojet drum, Dynojet claims it was 111 hp.

[F5 Dave]

Ok so let's play.
How would the 54hp of the RSA compare to either?

And is some of the conversion to bring it close to crank hp vs at the drum maybe?

[Sketchy_Racer]

It looks to me, that DynoJet's are a little bit optimistic but seem to give consistent results between individual units.


I once hooked my software onto the Dynojet of nearby Ten Kate (superbike world champ at the time), so each run on the Dynojet was simultaneously monitored by Dynojet software and FOS software. Clear outcome after a series of runs: when a bike delivers 100 hp on the dynojet drum, Dynojet claims it was 111 hp.

Yes, this is exactly my experience and conclusion.

We can all fool ourselves and enjoy seeing a larger 'measured' power output though....

[Frits Overmars]

Ok so let's play. How would the 54hp of the RSA compare to either?It wouldn't. The RSA power is measured at the gearbox exit shaft. So no varying losses through a chain that loses its lubrication over time and above all no wildly varying losses through the distortion of a tire on a drum, which will heat up the tire, which will raise the tire pressure, which will influence the distortion.
Measuring rear wheel power may be convenient for various purposes, but not for engine development.


And is some of the conversion to bring it close to crank hp vs at the drum maybe?If Dynojet would say so, I would be willing to accept that, even if their 11% exaggeration is neither a constant, because of the unpredictable tire losses, nor very realistic.
Total power losses between crankshaft and dyno drum will rather be in the order of 15%. But Dynojet just let you think that what you see on their software is the measured power.

[lohring]

By the way, one British horse power is 1.014 metric horse power. That's 33,000 ft pounds per minute vs 4500 kg meters per minute. Pounds and killograms are force, not mass for these definitions.

Lohring Miller

[JanBros]

started trying to make a very cheap DIY programmable ignition a french dude developed years ago :
https://www.youtube.com/shorts/tDq2E59a49A
works up to 20.050 rpm for now (that's as fast as my motor goes)

didn't wat to polute the topic with it too much, so opened a new topic about this :

https://www.kiwibiker.co.nz/forums/showthread.php/190568-cheap-DIY-programmable-ignition?p=1131242121#post1131242121

[ApolloMotoMoto]

started trying to make a very cheap DIY programmable ignition a french dude developed years ago :
https://www.youtube.com/shorts/tDq2E59a49A
works up to 20.050 rpm for nof (that's as fast as my motor goes)

didn't wat to polute the topic with it too much, so opened a new topic about this :

https://www.kiwibiker.co.nz/forums/showthread.php/190568-cheap-DIY-programmable-ignition?p=1131242121#post1131242121


Thats REALLY COOL.

Ignition system design and configuration is literally more "black magic" and "dark arts" than 2-stroke state of the art tuning theory is.

Its not horrendously complicated, nor does it require savant level electrical/ circuit knowledge...

But the "fundamental principles" and the "equivalent circuit" models that are best used to analyze and describe spark ignition systems are not ...well communicated... by the industry itself, or by those DIY'ers playing and sharing their work.

I am also doing a lot of work on "custom" ignition circuits that are open public knowledge.

I have a question for the other Guru's out there that have played with measuring and tinkering with ignition systems:


Is there a generally accepted "best setup" for an AC-CDI ignition dyno?

I want an electric motor that can spin, wall balanced and reliably, up to 20k RPM's.

I want some kind of "shaft rpm" readout because I wont always be testing with a full ignition system that would allow RPM reading off the tach-signal wire.

I want highly granular dynamic control of the RPM the motor is spinning at.


What motor/speed controller setups are people using out there for this kind of work?

[lohring]

I run electric RC model boats among others. Our electric motors easily spin much higher than that with over 3000 watts (4 hp) of power. What power or torque do you need? There are relatively inexpensive motors and speed controls available for lower powers. I use Castle Creations speed controls that have built in data loggers that read voltage, current, and rpm. With some more information I should be able to find you something for around $100 to $200 US.

Lohring Miller

[lohring]

After reviewing the other thread I see you don't need hardly any power. You could try drone motors and speed controls like these:

https://hobbyking.com/en_us/aircraft/drones/motors-accessories.html
https://www.amazon.com/Surpass-Hobby-S2810-Brushless-Racing/dp/B0CRQ15D5D?crid=1QJZDLR3BGHRK&dib=eyJ2IjoiMSJ9.2Ewn75QYUpBQK0m0ztIOowtuBN86yw-q_kIHRgVfiCJQTbYKSKvG_xwBje-Rl3tlSVfSbemKTHYUPlbvBm5ZTNMB0ua-EDUHCmS_8Jp_dW3534SS4Mb4EAFmMNHEjKy5yrWqrFG527JBiW-W0c_UjYzVQYcN42oDbxJsOqJpxxciuhaaSnMiKOR7yaKXqMr-LQVkKNIvcrsc8Ll4gnduBrM_w3ldjfdlTUwjKC22Um4m7iS29--8ywPrMkzCDAjOFVJ3AcW4Fm4O3pyIEft9xUeSF96SOnas3aie6 bPL6xM.wxXsCfzX9DQrrQMhHm-ah2EyntYhgMRckhJdhJj5p3Y&dib_tag=se&keywords=drone+motor&qid=1764782079&s=industrial&sprefix=drone+motor%2Cindustrial%2C176&sr=1-19
https://www.amazon.com/Brushless-Electronic-Components-Accessories-Helicopter/dp/B09DG18V6K?crid=3VNB94XPHA8A&dib=eyJ2IjoiMSJ9.aCRR17bFt3Wj4tabjW5Lv5ehPvmi8E8Iv OwAEkUdNCiY4nlidwCioyVWE4z63WG9pUpuahV9oIypkoKZ24W lCqRTBB5N0ZFiwixMayweKdQBAgR4VJjYf-WT5mgIvjDO87jLnCEnnZMq2d8ItDPOAfwInSiq7VNF2lf62vGd UFCWqRfJFPX81j8JNFsFOb1Hf6oH2orWUqw3_clE1i1IsXdVbC eWJuNIw_7RhfVS6fsNQsxj_BJSypzXYp3QUGmL4UobxPJynZns Easrv4Ghm3Vgc9dFvzKM7uuWYW36uEo.wLKoW908So4n5UGTNG pR9-3M3hfnFLHWijW4Pqi3TqU&dib_tag=se&keywords=drone+esc+and+motors&qid=1764782259&s=industrial&sprefix=drone+esc%2Cindustrial%2C193&sr=1-9
https://hobbyking.com/en_us/turnigy-plush-32-40a-2-6s-brushless-speed-controller-w-bec-rev1-1-0.html
https://www.amazon.com/VGEBY-Brushless-Controller-Airplanes-Accessory/dp/B08XZB9FX9?crid=3VNB94XPHA8A&dib=eyJ2IjoiMSJ9.nszCiy0O0mQZuyfQ154TrOb8oxQSY05JI mKBraJfPXpdG9Kio3Kmzns4ZQA_RSajMuna-Mm7YTSFbSYeJnpS6WeBAjaiUyHZEJuFdaTJGqqQpdh02fKL_5z bUyGwtfKm59ndKBS-9ZjRx2MxuePvN1vUY-t-78l1LKxygnsYxDGG5fVEC65LHjdlVbVNlhDFJV5e2zGBV5Jbux-DZl9eTcu2cmFxvlGySXNuACbgYZqSgqpEkdCTYMGfakvR-cyxCALP8PWtIIM8N-3wDDXv339s6zz-cWbsWlewo-4nas0.RnnGx8WLlhub3F7Ga24wiCfqvt2uJ-xlBgcGPN1wG9g&dib_tag=se&keywords=drone+esc+and+motors&qid=1764782349&s=industrial&sprefix=drone+esc%2Cindustrial%2C193&sr=1-10

The motor's no load rpm = input voltage x KV The actual rpm will be around 80% of that depending on the load. I would run around 12 to 16 volts from any source or battery that can supply up to 40 amps. You control the speed with a servo input to the speed control. See below for a servo tester to do that:

https://www.amazon.com/dp/B012LZKTDO?ref=ive_vfsp_pfo&_encoding=UTF8&pd_rd_w=w46gN&content-id=amzn1.sym.26dedd2b-540b-4bff-af75-7fea8d8f8913&pf_rd_p=26dedd2b-540b-4bff-af75-7fea8d8f8913&pf_rd_r=77JFTGZ35K51Q0JCN865&pd_rd_wg=leZSP&pd_rd_r=acbf1a89-2475-4b07-98c2-66345747ccca_vse-cards-ingress2

Lohring Miller

[diesel pig]

Hello Brains trust,

I am wondering if anyone can advise me on removing the powerjet tube that protrudes into carb bore?

specifically on a keihin spj.

The issue I have is that the tube's outlet/discharge is facing away from the carb slide and need to be rotated 180.

I am assuming they are a press fit but do not want to destroy the tubes or the carbs

Thank you!

I am not one of the Brains trust, But the only thing I can think of doing is use a industrail heat gun (not a Hair dyer as it would not get hot enough) to heat up the carb while it is in some kind of vise set up. Once as hot as you can get it use some soft nose piers to turn the tube. I am sure someone would tell us if that would work.

[katinas]

Thats REALLY COOL.

Ignition system design and configuration is literally more "black magic" and "dark arts" than 2-stroke state of the art tuning theory is.

Its not horrendously complicated, nor does it require savant level electrical/ circuit knowledge...

But the "fundamental principles" and the "equivalent circuit" models that are best used to analyze and describe spark ignition systems are not ...well communicated... by the industry itself, or by those DIY'ers playing and sharing their work.

I am also doing a lot of work on "custom" ignition circuits that are open public knowledge.

I have a question for the other Guru's out there that have played with measuring and tinkering with ignition systems:


Is there a generally accepted "best setup" for an AC-CDI ignition dyno?

I want an electric motor that can spin, wall balanced and reliably, up to 20k RPM's.

I want some kind of "shaft rpm" readout because I wont always be testing with a full ignition system that would allow RPM reading off the tach-signal wire.

I want highly granular dynamic control of the RPM the motor is spinning at.


What motor/speed controller setups are people using out there for this kind of work?

I use 1.5KW Air cooling Spindle Motor 24000rpm ER11 w/ 1.5KW Inverter VFD CNC, https://www.ebay.co.uk/itm/317553810908?, just older version.

But be careful if testing at home, loved ones can quickly leave you after constant testing !!!

[F5 Dave]

If you can get to the tube slide a section of nail in it in case you start to crush it. Leave a section of nail exposed for extraction.

[wobbly]

I have removed the PJ in that carb by clamping s piece of square steel in the vise, hold the PJ end square on the bar, and tap the body directly next to the pressed in ball.
The PJ tube and the ball easily came out doing this.

[wobbly]

Neels is still locked out - nothing has changed, the connection request times out.

[husaberg]

Neels is still locked out - nothing has changed, the connection request times out.


for clarity of the admins and mods
Neels is KB username Vannik
https://www.kiwibiker.co.nz/forums/member.php/34343-Vannik

[TZ350]

.
357106

Suggestions needed.

My good old new triple exhaust port methanol burning Kawasaki F81M 250 is suffering a serious bout of rough running around 8,000rpm.

Not a problem with the single exhaust port cylinder but a real issue with the tripple.

Things I have tried:-
Swapped out the Suzuki piston with the cutaway sides for a full skirt Wiseco one.
Reverted from my petrol/methanol carb setup back to a 100% methanol one.
Tried it with and without power jet.
Tried extreme richer and leaner main jetting. Jetting that makes best power also colours the plug and head. I would expect it to be clean.
Tried straight line ignition settings all the way from 5deg to 30deg BTDC. Over advanced can cause a patch of rough running.
Replaced the "R" retracted gap plug with a normal cold exposed tip one.
Tried plug gap settings from 010" to 030".
The coil is something that should be capable of throwing an arc across the room and welding heavy steel beams. Probably can create a spark underwater.
Both channels of the Race2 Ignitec discharge into the coil.
Checked that the Battery and generator can supply the ignitions current draw. About 4A at 10,000rpm.

Things that may be a problem:-
The scavenging stream is blowing the spark out.
The plug is slightly offset in the head and should be central.
Try it on petrol only. Although I want the methanol for cooling.

This was not an issue with the single exhaust port cylinder. The triple exhaust unit runs and sounds much better at 10,000 rpm than the single did.

Both my CHT and EGT gauges have chosen to go on the blink so not much help there.

Ideas???

[husaberg]

.
357106

Suggestions needed.

My good old new triple exhaust port methanol burning Kawasaki F81M 250 is suffering a serious bout of rough running around 8,000rpm.

Not a problem with the single exhaust port cylinder but a real issue with the tripple.

Things I have tried:-
Swapped out the Suzuki piston with the cutaway sides for a full skirt Wiseco one.
Reverted from my petrol/methanol carb setup back to a 100% methanol one.
Tried it with and without power jet.
Tried extreme richer and leaner main jetting. Jetting that makes best power also colours the plug and head. I would expect it to be clean.
Tried straight line ignition settings all the way from 5deg to 30deg BTDC. Over advanced can cause a patch of rough running.
Replaced the "R" retracted gap plug with a normal cold exposed tip one.
Tried plug gap settings from 010" to 030".
The coil is something that should be capable of throwing an arc across the room and welding heavy steel beams. Probably can create a spark underwater.
Both channels of the Race2 Ignitec discharge into the coil.
Checked that the Battery and generator can supply the ignitions current draw. About 4A at 10,000rpm.

Things that may be a problem:-
The scavenging stream is blowing the spark out.
The plug is slightly offset in the head and should be central.
Try it on petrol only. Although I want the methanol for cooling.

This was not an issue with the single exhaust port cylinder. The triple exhaust unit runs and sounds much better at 10,000 rpm than the single did.

Both my CHT and EGT gauges have chosen to go on the blink so not much help there.

Ideas???


Put a longer carb bellmouth stack or lengthen the intake to see if it shifs the rpm where it turns to shit.
Quick and easy, if its not that move on.
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=251900&d=1322903746

[jonny quest]

TZ350, I just looked at your triple exhaust port shape.

I think you are having short circuit problems. This is showing an extreme case I've never seen, but it typically shows up in your area of dyno curve.

Fill in the bottom of those sub exhaust with epoxy, and hope you can make a quick dyno run before it blows out and see what happens

By bottom, I mean just the area that is inline with A port

[wobbly]

It sure as hell isnt the ignition system, but for the 10,000 th time, are you using a " proper " fine wire race plug that needs 1/2 the gap voltage to ionize.

First thing to look at is when the piston is at TDC, does the piston side cutaways expose a lump of Aux real estate , connecting the case to the Exhaust duct
thru the side port ducts. That will run like shit.
Its unlikely to be the A port short circuiting out the main port as it wasn't happening before - but sure you could be seeing vertical linking of the A port roof and the Aux floor if they are
separated by a very narrow septum width ( and this is why wide topped triangle Aux work so much better).

I have seen a similar thing happen if there is not a resistor cap and plug combination, or if the coil drive wires are not physically separated from any other in/out wires all the way
from the CDI plug end to the coil.
Also a possibility that the fueling is going haywire due to the much lower Blowdown residual pressure at TPO.
Remember that the mid range fuel curve is set by the needle/tube annulus area for low rpm/WOT.

[Frank S.]

To me this looks like a kind of resonance problem, because it only appears in a sharp band from about 8700 to 9700rpm. This is about 145 to160 Hz. Below and above this it runs fine.
Are there parts that can swing in resonance like carb, coil or something? Check the whole bike for loose parts.
Did you check the ignition timing with a strobo lamp at that rpm?

[ApolloMotoMoto]

.
357106

Suggestions needed.

My good old new triple exhaust port methanol burning Kawasaki F81M 250 is suffering a serious bout of rough running around 8,000rpm.

Not a problem with the single exhaust port cylinder but a real issue with the tripple.

Things I have tried:-
Swapped out the Suzuki piston with the cutaway sides for a full skirt Wiseco one.
Reverted from my petrol/methanol carb setup back to a 100% methanol one.
Tried it with and without power jet.
Tried extreme richer and leaner main jetting. Jetting that makes best power also colours the plug and head. I would expect it to be clean.
Tried straight line ignition settings all the way from 5deg to 30deg BTDC. Over advanced can cause a patch of rough running.
Replaced the "R" retracted gap plug with a normal cold exposed tip one.
Tried plug gap settings from 010" to 030".
The coil is something that should be capable of throwing an arc across the room and welding heavy steel beams. Probably can create a spark underwater.
Both channels of the Race2 Ignitec discharge into the coil.
Checked that the Battery and generator can supply the ignitions current draw. About 4A at 10,000rpm.

Things that may be a problem:-
The scavenging stream is blowing the spark out.
The plug is slightly offset in the head and should be central.
Try it on petrol only. Although I want the methanol for cooling.

This was not an issue with the single exhaust port cylinder. The triple exhaust unit runs and sounds much better at 10,000 rpm than the single did.

Both my CHT and EGT gauges have chosen to go on the blink so not much help there.

Ideas???


"Tried extreme richer and leaner main jetting. Jetting that makes best power also colours the plug and head. I would expect it to be clean. "

Okay, thats a PURE combustion efficiency problem right there, previously you had complete combustion at these jetting settins, now you cant (coloring the plug and head at lambda values that previously burned "clean")

You also swept up and down the stoich lambda curve and nothing "fixed it".

What does this mean?

Even when you sweep to the stoich value that is the "easiest" to ignite for the fuel you are using, spark initiation is still failing.

With the fuel you are burning (hard to ignite alcohol fuels) AND the increased BMEP the engine is making with tripple exhaust port; high dynamic in-cylinder pressure at the moment of spark firing = higher required breakdown voltage AND dV/dt.

delta Voltage divided by delta Time

You can have all the voltage potential in the world with the capability of throwing the gap from here to the moon in a steady state, with UNLIMITED time to achieve breakdown....

But, that is not what Paschen says happens in a dynamic townsend regime that includes a "time-domain" function.

Literature (lab studies of plasma formation at internal combustion engine cylinder pressures/conditions) suggests that the required breakdown voltage to initiate the spark gap MUST BE ACHIEVED within 1-5 uSecs (0.001 - 0.005 seconds) or breakdown formation "LAG FACTORS" overcome the rising kV potential comming from the high voltage transient discharge from the CDI, through the COIL and into the spark gap.

This means:

If your systems RISE TIME for the first HIGH VOLTAGE transient pulse that is meant to "jump the gap" is TOO SLOW, it doesn't matter if you have 100,000 kV of open-circuit, open air POTENTIAL; you will fail to achieve breakdown for real in-cylinder conditions that maybe only need 20-30kV of VOLTAGE at the gap because you built your potential (rising rate) too slow.


Okay, thats problem number one.


Problem number two:

Lets assume you DID achieve breakdown, you DID jump the gap, and you DID establish a "nascent kernel".

Why is combustion proceeding so slowly and inneficiently around where the engine makes peak power/ peak cylinder pressure/ and probably peak MSV Turbulence....???

Turbulent conditions after the nascent kernel forms are "quenching" it before the CDI's discharg regime "catches up" and dumps the remaining energy stored in the discharge caps as lower volts and higher amps.

Once breakdown forms the kernel, the plasma channel becomes nearly superconductive; what was once an infinite resistance air-gap is now a highly conductive plasma channel, the volts required to sustain the arc are more like 800 - 1000V, so the remaining energy flows at higher relative current and lower relative volts.

This "post breakdown" current flow stabilizes the nascent kernel, grows its diameter, and delivers heat energy to this kernel.

It is CRITICALLY IMPORTANT that this post breakdown current is delivered in a window around 0-200 uSecs after breakdown occurs.

You dont want ALL of the current dumping in this quickly, but you MUST have SOME meaningful current delivered in this time window to stabilize the nascent kernel, or turbulence can ABSOLUTELY "blow out" the already established nascent kernel.

IDEALLY, you have a front-loaded current delivery window that dissipates a good margin in the first 200 uSecs, with a still meaningful "tail" that delivers energy over ~800 to 1,200 uSec total "spark energy delivery window".

None of this is necessary for a "simple" petrol burning engine at low to moderate BMEP and combustion chamber design "turbulence factors".

For an alcohol burning engine that wants RICH stoich values for best power, tuned to a high BMEP state, using a well optimized combustion chamber producing ...high... "turbulence factors", on the other hand:

This "time-domain" factor now becomes a lot more important to tune for in your ignitions discharge regime.


Attached is a document you have probably seen 100 times before from Frits, but it really does seem to match the condition you see on your dyno VERY well, especially the "saw tooth" pattern within the "power hole".



Now, you are using Wayne Wrights recommended CDI setup for this EXACT scenaio: jungle juice near impossible to light fuels at high engine BMEP with high turbulence head designs:

IgniTech 2 cylinder DC-CDI box with the outputs paralleled into one coil.

The questions I have are the same as Waynes:

1. Are you using the recommended NGK Race Plug?

Double fine-wire (laser welded fine-wire ground strap), Double rare-earth (irridium electrode, platinum ground strap)

NGK R7376 or equivalent.


2. Are you using the Crane Cams PS91 Ignition Coil Wayne ALSO says to run with this setup???


The "time domains" that I described above are mostly controlled by the natural resonant frequency of the CDI/Ignition Coil combination.

The capacitor(s) in the CDI and the "inductor" represented by the ignition coil (in addition to the resistive/inductive/capacitive contribution of the coils windings and the full circuits wiring loop) form an "LC Tank" equivalent circuit with a time-domain defined by the RLC of the combined components in the circuit loop.

This is one of the reasons Wayne recommends the Crane Cames PS91 coil specifically, when paired with the dual/parallel IgniTech DC-CDI setup, the natural resonant requency produced establishes a set of "discharge event time domains" that ACTUALLY WORK.


If you go arbitrarily trading out pieces of this setup, like for example, the ignition coil; for a different part with inductance/resistance/stray capacitance values that are much different than the Crane Cams PS91, then its entirely possible you skew the time domains into a region where you make PLENTY of power, just too late for it to actually mean anything to the spark kernel as its getting blasted by in-cylinder pressure and turbulence.



Wayne ALREADY HAS a setup that is KNOWN to work under these conditions.

If it IS a spark-loss condition, my FIRST recommendation would be to replicate Wayne's setup EXACTLY if you have not already done so.

[TZ350]

If it IS a spark-loss condition, my FIRST recommendation would be to replicate Wayne's setup EXACTLY if you have not already done so.

Thanks. I think I have the right coil and I have one of those plugs. I will check through the system and do my best to replicate Wobblys setup.

[F5 Dave]

I thought he was going to conclude by saying Tap the plug on the side of the head and close the gap up a bit:pinch:. At least check it I suppose but unlikely to be wrong thee days on million dollar plug. Funny fuel seems to play by odd rules.

[wobbly]

Using the prescribed plug/coil/DCCDIP2 arc welder ignition was developed for a World Champ mini hydro 125 making well over 60 Hp @ 14000 on straight Methanol with 20:1 compression.
Man, if it can fire that up easily , the little Kawasaki is a walk in the park.

Edit - I even asked Jiri the tech at Ignitech if it was possible to program a delay into the twin spark setup, to increase the overall burn period in the gap.
He tried it, and replied that it kept blowing the output capacitors apart, he thought due to the coil ringing and the caps seeing nulls - and worse, huge superposition voltages.

[Hoebra]

I got a question about finding proper jetting dimensions for Powerjetaplications, espacially for wobbly cause i know he used these components alot.

I got a electrical Mikuni powerjet, wich i want to use with my ignitechs pwm function to keep egt longer up after peak power. So i asked myself if there is a kind of "rule of thumb" how big to choose the powerjet nozzle. If it is bigger and you turn off after Peak Power, a bigger amount of fuel dissapears an egt will rise/keep up in a bigger value. But fore shure theres a "to much", "less then possible" and a "sweet spot".
So lets say in an non Powerjet Szenario you found a mainjet with "100" flowrate as perfect. Is there a relationship to say it would be a good starting point to choose for example 25% of this mainjet flowrate as powerjet flowratesize? Of course the mainjet in the Powerjetaplication would have to become less big, becaus of the extra amount of fuel the powerjet is adding. I guess it isnt as simple as saying 100-25=75... so theres maybe some testing, starting richer (like about 85?) and testing down leaner until you reach about the same egt/peak power like with the 100 mainjet.
From there starting with shutting Powerjet off via PWM. Could you show such a PWM table in the ignitech software, becaus until now I have no real idea how to start. Thanks!

[TZ350]

If it IS a spark-loss condition, my FIRST recommendation would be to replicate Wayne's setup EXACTLY if you have not already done so.

357294

Damm expensive plug, about 80-120 NZD each.

357295

Lead and cap 9,6k Ohm

357296

FireBall PS92N

357297

Ignitec DC_CDIP2_Race with both the white and orange wires paired and going to the coil.

357300

[TZ350]

.
357298


It sure as hell isnt the ignition system, but for the 10,000 th time, are you using a " proper " fine wire race plug that needs 1/2 the gap voltage to ionize.

I am a pensioner so No, not been but I have one and will try it. The NGK R7376-10 is so damned expensive.


First thing to look at is when the piston is at TDC, does the piston side cutaways expose a lump of Aux real estate , connecting the case to the Exhaust duct
thru the side port ducts. That will run like shit.

357299

Looking at the old Suzuki piston in the single exhaust cylinder it looks very possible that the side exhaust ports may be opening into the crankcase at TDC.

I will have to take the good cylinder and piston off to check ........

Cylinder off will be the first move.

[wobbly]

The best place to buy the NGK plugs is JDM Planet - very reasonable shipping as well. But here is another idea I have been using for some time now.
A NGK R0373A is the 10mm version of the R7376 , and is cheaper, plus it enables a minimal boss intrusion into the chamber when using a Toroidal dome
to reduce the shadow or masking effect on the loop flow across the dome face.
This idea was proven ( though sworn to secrecy ) via a World Champ winning big bore snowmobile project.
The small resistor caps to suit are cheaper as well - I got a bunch from a British Bike parts place in ChCh I think.

And yea, if your Aux are linked to the case - the jetting goes completely to shit.
Same thing happened when I cut the skirts short on a " stock " World Champ Jetski with a 2: 1 pipe setup.
The fuel curve went out the window completely, and it was only due to having pumper carbs with Aux venturi's that allowed the thing to be dialed back in.
Made a shit ton of top end power, and won a title with zero chance of any tech seeing what had been done.

[Larry Wiechman]

357296

FireBall PS92N







PS91 or PS92, 3 Ω or .82 Ω, which one is preferred?
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=357190&d=1765144544

[Hoebra]

About the dip in the powercurve: Maybe not thge spark is lost in this rpms, but AFR is crazy wrong? Looking at the curve it is about the rpm of maximum torque. Have you made any changes to your scavening or your diffusorcreation? Once your scavening is less stiff than before, or your main Depression pulse is much stronger so sthe scavening colapses as it hits, leaving a lot of burned gases inside, as the this maindepression pulse gets weaker scavening becomes stiff enough again and AFR gets back to normal.
Had such phännomena by testing diffusor dimensions on non full race cylinders. Got good good curves with mild diff anngles, by increasing them torque an power rised, until a point of 18°+ main diff angle, curve startet at the same RPM with even higher torque, dipped than completly around max torque rpm and after this again went on with more torque than before, but in the region of the heavy main depression pulse great dip in the torque/powercurve, so to much Depression for the stiffness of this scavening.

[wobbly]

The coil I used was a PS92N, built for Nascar CDI systems.

[ken seeber]

The man says:

"Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one."

Just maybe it's true:

357439

[wobbly]

Kentastic, that was a line from a Joni song - she's older than me, but I would hope some much younger ladies would like that version of me, due to obvious physical enjoyment.

[husaberg]

Picture albums they have multiple pages at the bottom

Aprilia GP bikes https://www.kiwibiker.co.nz/forums/album.php?albumid=4839
Cagiva GP bikes https://www.kiwibiker.co.nz/forums/album.php?albumid=4842
Honda NSR500 https://www.kiwibiker.co.nz/forums/album.php?albumid=4837
Suzuki RGV500 https://www.kiwibiker.co.nz/forums/album.php?albumid=4848
Yamaha YZ500 https://www.kiwibiker.co.nz/forums/album.php?albumid=4845
Honda NSR500V https://www.kiwibiker.co.nz/forums/album.php?albumid=4953
Swissauto ELF pulse 500 https://www.kiwibiker.co.nz/forums/album.php?albumid=4833
Honda Rs125 RS250 https://www.kiwibiker.co.nz/forums/album.php?albumid=4841
Suzuki RGV250 GP bikes https://www.kiwibiker.co.nz/forums/album.php?albumid=4938
Yamaha TZ250-350 https://www.kiwibiker.co.nz/forums/album.php?albumid=4882
Yamaha TZ750 https://www.kiwibiker.co.nz/forums/album.php?albumid=4932
BSL500 https://www.kiwibiker.co.nz/forums/album.php?albumid=4865
Rotax and other tandems https://www.kiwibiker.co.nz/forums/album.php?albumid=4840
Patton https://www.kiwibiker.co.nz/forums/album.php?albumid=4849
Roberts 3s https://www.kiwibiker.co.nz/forums/album.php?albumid=5025
Honda RS and NS500 https://www.kiwibiker.co.nz/forums/album.php?albumid=4861
Kawasaki H1R and H2R https://www.kiwibiker.co.nz/forums/album.php?albumid=4964

plus many others
there are about 100 albums most are open
https://www.kiwibiker.co.nz/forums/album.php?u=28036

[diesel pig]

Damn you Husberg! I now know what I will be doing this Xmas.

I got a little weirded out when I check out the JDM Planet site it's a car parts site but they do have all types of NGK plugs for reasonable prices.

[crbbt]

I have removed the PJ in that carb by clamping s piece of square steel in the vise, hold the PJ end square on the bar, and tap the body directly next to the pressed in ball.
The PJ tube and the ball easily came out doing this.

Thank you!

this worked. Now to find your post about putting the 0.2mm hole into tube to atomize the fuel coming out of the PJ

[husaberg]

..............

Thank you!

this worked. Now to find your post about putting the 0.2mm hole into tube to atomize the fuel coming out of the PJ


Here's a mod I have done on many Yamaha racebikes with the electronic solenoid PJ - move the PJ to the top of the bellmouth and shorten the dump tube so it
only protrudes around 15mm into the bore . I cut the tube end at 45* facing the reeds as this atomizes the fuel stream much better than the stock small hole does.
The slide has to be well past the tube end for flow to begin , having a low down tube richens the fuel curve way too much in the midrange.

The only other way is to use a truth table in the ecu to switch the flow depending upon TPS and rpm , but this is problematic to tune , causing jerking response on part throttle , mid corner.
Cutting the tube short works on Lectrons as well , when having to use large PJ flow ( 50 + ) to get the top end tune correct without shagging the midrange jetting.


Re the tiny bleed hole in the TZ powerjet tube - I always thought that this was a good idea to emulsify the fuel as it exited the dropper.
But years ago i did some wet tests on the flowbench with a VCR video camera ( pretty trick shit stuff back then ).
The Mikuni was a horror scene when played back slo mo,with huge "gobbs" of fuel exiting the main and powerjet.
We then stuck on a Lectron - wow, lovely fine mist of fuel from the back of the flat needle face - and it flowed 12% more air - size for size with a venturi 2mm smaller behind the slide.

Next is the current state of TeeZees GP125, here is the latest dyno curve digitised with 16% added to simulate crank power.
Then there is the sim with an actual RS early model pipe.
Then there is the new pipe of my design.
Of most interest is that in this case the sim is giving slightly too much crank power - but the shape and peak point are all but perfect.
I would be confident now that any change in the sim, would be reflected in reality on the dyno.
In my experience the later Dynojets like a twin roller 168 with Eddy current load control to slow the acceleration rate down ,seem to read around 5 to 10% lower
so this would put the sim and the dyno reading very close, as the shape is spot on now.


When using a simple powerjet nozzle the tip position matters in that no flow will occur until the slide is well past the exit hole, and there is sufficient airflow
to drag fuel up the feed tube above the bowl level.
With the aftermarket add ons and the ones as used by Lectron you can shorten the dump tube so that the flow will only occur at high slide openings,as well as high air flow.
These also have a built in "lag "control in that it takes time for the fuel to rise up the tube and dump out the exit into the air stream.
With a solenoid controlled setup all this is pretty much irrelevant as the flow can only occur when the solenoid is not powered up, and this
is TPS as well as rpm dependant inside the ECU program..
The carbs as used on the MX bikes has the dump tube very low in the bore as they added and subtracted fuel at low slide positions in those bikes.
For a race engine I bend the tube up to around 1/2 bore, as this is where the exit is on the Kehin SPJ carb for RS125/RS250 Honda.
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.
This causes a problem with Ignitechs that are used with only a capacitor, as at startup the solenoid is powered up, dragging all the voltage out of the ECU, so I convert the ECU output
to a 3 step truth table, and have the setting such that below 1500rpm the solenoid isnt powered.

[crbbt]

Thank you Husa,

I gave up after an hour.
Not sure where I recall the 0.2mm hole from however

[wobbly]

First off, still nothing has been achieved to get Neels ( Vannick ) from being unblocked on here.
C'mon guys this is getting ridiculous.

The hole in the PJ dump tube idea came about when I first got access to Robert Taylors new portable dynojet.
I wanted to make something similar to the newly available Dialajet , and Intelajet setups from Thunder Products that had a fixed fuel jet, but made it adjustable by bleeding a variable amount of air
into a small volume sitting on top of the PJ tube.
This operated just like a normal main or idle air corrector, bending the fuel curve such that as the bulk air flow increased, the fuel flow was gradually decreased, countering a 2T carbs
natural tendency to run richer and richer - even though power is decreasing.
The other advantage was that bleeding air into the PJ circuit also helped to reduce droplet size due to better emulsification.
The short story was that I could never get that system to make any better power.

But during the dyno session I looked at the PJ's on a late model TZ250 and it had a tiny hole in front of the PJ tube - doing that made better top end overev power.
At the time I was also cutting the engine side of the emulsion tube shrouds off at an angle, making the top of the shroud a small radius facing the airflow, tapering down at an angle to no cut on
the carb floor facing the engine.
This was tested and proven during the dyno work at ZipKart on the Rotax 256.
So at the last minute I filled the 0.2mm front hole in the PJ and cut its end off at 45* facing the engine - this was better everywhere.

[TZ350]

.

357473 357474 357475

Ok, at first glance. Uncovering the exhaust ports at TDC does not look like it is the issue.

But a more careful look may be warranted as the cylinder could be slightly rotated and that may expose an edge of an exhaust boost port.

357476

[crbbt]

Thanks for the insight Wob!

I'll get some more tubes made up and go for the 45 angle on the discharge

[Frits Overmars]

357474
at first glance. Uncovering the exhaust ports at TDC does not look like it is the issue. But a more careful look may be warranted as the cylinder could be slightly rotated and that may expose an edge of an exhaust boost port.I can't say for sure that your problems are caused by transfer short-circuiting, but it seems certain that you do have short-circuiting, unless you have used piston plugs.

[husaberg]

It would be pretty easy to say super glue some cork plugs as a trial to see if that is the major issue it only needs to last a few minutes soak the ends in an epoxy or similar, if they break off little harm done.

[F5 Dave]

Re Neels
I know nothing about website access issues but can he create a new account with a different email perhaps?

[husaberg]

Re Neels
I know nothing about website access issues but can he create a new account with a different email perhaps?
Use a proxy with a NZ location?

[wobbly]

I will suggest that to Neels.

TeeZee, if you find you do have Aux/A port linking, the way this was solved in the kart engines to enable running no plugs, was a full triangle shape on the Aux, such that only the very small top corner
radius of the Aux was in play, for only a very short time.
The top edge of the Aux can be much longer, utilizing the high Blowdown Pressure Ratio at APO
The other thing I see is the off the wall Aux shape dead in front of the A port - absolutely incurring short circuiting around BDC when the port depression is greatest .
I have used Hi Temp Ceramic paste in the Exhaust duct when testing the exit reduction idea, it never failed on the dyno - JB Weld make one.

[wobbly]

Neels very grumpy reply - " I cannot access the kiwibiker at all, not even as non-user. "

[TZ350]

The other thing I see is the off the wall Aux shape dead in front of the A port - absolutely incurring short circuiting around BDC when the port depression is greatest .
I have used Hi Temp Ceramic paste in the Exhaust duct when testing the exit reduction idea, it never failed on the dyno - JB Weld make one.

357490

The exhaust duct tunnel was dug at the bottom of the axillary port because that brought it out between the cylinder fins. I will have to think about how I can change this.

[TZ350]

TeeZee, if you find you do have Aux/A port linking, the way this was solved in the kart engines to enable running no plugs, was a full triangle shape on the Aux, such that only the very small top corner radius of the Aux was in play, for only a very short time. The top edge of the Aux can be much longer, utilizing the high Blowdown Pressure Ratio at APO.

357491

After doing lots of fancy difficult measurements trying to work it out. I figured the easiest and best way to check for port/cylinder rotation was to assemble it all up and draw a line across the piston at TDC.

357492

Then disassemble it, pop the piston back in at TDC, align the pen marks and look inside.

357493 357494

Simple as, after wasting time doing it the hard way. A quick check and there is no exhaust or Ex axillary port exposed at TDC.


I can't say for sure that your problems are caused by transfer short-circuiting, but it seems certain that you do have short-circuiting, unless you have used piston plugs.

357496357495



Piston pin plugs might be the next move. Last time I tried them they rattled loose and the transfer port shaved them away until they were just a ball of ally rattling around in the end of the piston pin.

[wobbly]

As I said you dont need pin hole bushes, a proper triangle Aux shape fixes both vertical and horizontal linking/short circuit issues.
More especially in your case due to having nothing like the RSA bmep, you dont need to even go close to bore center.

[TZ350]

I have used Hi Temp Ceramic paste in the Exhaust duct when testing the exit reduction idea, it never failed on the dyno - JB Weld make one.

I will see what I can find. I should be able to fill part of the auxiliary port to get a more triangular shape.

I have to say no more HP but with the auxiliary exhaust ports, over rev was greatly improved. It would run out past 10,000 rpm with ease.

[Wos]

The auxiliary seem to act very late after main exhaust opening !?
Most of the job seems to be done by main and its blowdown area

Maybe better to keep auxiliary small, away from transfers, away from center of bore and set them higher, let them only act in blowdown area

[jonny quest]

TZ350

Do you have capabilities for a wide band AFR? In real-time in dyno run?

When I originally replied I thought it was more of a short circuit thing between A and your odd shaped auxiliary ports.

You may see that with AFR.

If your carb needle is too rich, this will show up on dyno like this too.

What does bike sound like holding a steady state with slide in needle operating range? Does is blubber and not zing right through the RPM's?

Make a marker line on piston and show us the A transfer angle

[TZ350]

357499 Piston pin plugs.

357500 Reference cylinder.


TZ350 When I originally replied I thought it was more of a short circuit thing between A and your odd shaped auxiliary ports. Make a marker line on piston and show us the A transfer angle

357501 Port discharge angles.

357502 357503

Alloy welding wire indicates placement of axillary port duct which is between the fins. My method to make the duct was to drill through between the fins. That initial drilling came out in the cylinder between the A and Ex ports. The upper part of the axillary port was cut into the wall of the cylinder with a mill. Speedpro handled the tricky milling job. I dug out the cylinder to connect the two parts, port and duct.

Yes. Quite a difference between the reference cylinder and mine in the area between the Exhaust port and A port. Might be a clue about where I am going wrong.


TZ350 Do you have capabilities for a wide band AFR? In real-time in dyno run?

Not now but I did use one and a data logging program with my 2Stroke EFI project.