ESE's works engine tuner

[dutchpower]

Mister Copy :lol:

[wobbly]

Jan , it surprises me you said the Czech machine was not used at Aprilia. The Yamaha engineer who did the 2000 YZR250 winning bike ( named Suzan in ringlish ) said it was so good he could tell exactly what
power a cylinder would make without needing the dyno.
And Bud Askland when developing the KR3 cylinders said the Czech machine showed him how good the factory 250 cylinders were , but also he learned exactly what to change from viewing the in cylinder
scavenging patterns.
Ive only seen a couple of pictures of the thing , but not any results it produced.

[lodgernz]

I need to drill a couple of oil holes in my piston to lubricate the ex port divider.
Can someone please advise where vertically to drill them? Like just below the ring land or further down for the top one?

[wobbly]

15 and 35 down from timing edge on 54.5 stroke

[lodgernz]

15 and 35 down from timing edge on 54.5 stroke

Perfect. Thank you Wobbly.

[skako]

Comparison of simulations
In the simulation program that I put together according to the first book by Prof. Blair, I made hundreds of simulations presented in the form of graphs.
Despite all the limitations and shortcomings, the graphs gave me a relatively good and quick qualitative insight into the simulation results.
I was interested in settings that are not common in engine construction.
These simulations showed that the properties of the output result are affected to some extent by the length of the transfer.
For a more accurate result, I now use EngMod2. I set up an air-cooled model with a target BMEP of 15 bar, with the STA timings set accordingly.
Through several steps of Deto-Analysis, I set the ignition times so that there are no detonations. Thanks again Wobbly for the warning and helpful advice.
I have limited the model which in some dimensions resembles cylinders that already exist. I was interested in how two different scavenging models would behave.
In this simulated model, the RSW scavenging model gives approx. 1.2% more peak power compared to the LoopSaw model. In the other modes of operation, the results are almost the same.
Despite the targeted high BMEP and high STA, the BMEP result is approx. 20% lower than required.
I have shown part of the other data on the additionally edited EngMod2 output graph.
Maybe these graphs will help someone and lead them to additional thinking about engine construction.
354197

[wobbly]

I have a hundred questions on the methodology for this.
Is this a Rotary valve engine , is the case ratio for the long or short duct , what was the fuel , what was the CE , was the Combustion file derived from a Turbulent model run that had been imported,
how clever is the pipe design etc etc.
The very best RSA sim I can construct is short of the actual crank power expected , as there is no way of modelling the correct Ex port timing that takes into account the actual large port Cd increase due to the
timing edge radius Jan added to enable any performance from the sub optimal pipe design given to him.
Thus that sim has a sub optimal Blowdown STA coupled to the sub optimal pipe , and as such cannot accurately replicate reality.
In short im struggling to gain any worthwhile insights from your data due to a severe lack of supporting info.

[skako]

I have a hundred questions on the methodology for this.
Is this a Rotary valve engine , is the case ratio for the long or short duct , what was the fuel , what was the CE , was the Combustion file derived from a Turbulent model run that had been imported,
how clever is the pipe design etc etc.
The very best RSA sim I can construct is short of the actual crank power expected , as there is no way of modelling the correct Ex port timing that takes into account the actual large port Cd increase due to the
timing edge radius Jan added to enable any performance from the sub optimal pipe design given to him.
Thus that sim has a sub optimal Blowdown STA coupled to the sub optimal pipe , and as such cannot accurately replicate reality.
In short im struggling to gain any worthwhile insights from your data due to a severe lack of supporting info.

The model is piston port inlet, transfers are for long channel type, fuel is Unleaded 95, Comb.Eff. 0.95, AFR 12, combustion file imported from turbulent model.
CE, DR, Purity, graph attached. Since I'm new to using this sim, I might be doing something wrong.
I appreciate your comments, please tell me which file you need and I will deliver it to you, no problem.
354198

[wobbly]

DM sent with email for your .pack file , but just quickly having a CE of 0.95 is impossible with pump fuel as is running 12:1 A/F

[p12palof]

Good morning from Spain, friends!!! I have reading this forum from many years and today is the time to make many tuning questions. Thanks for all the knowledge sharing here :not:

One of my bikes is a tuned Honda CR500 '94:
-Ported cylinder
-Billet Cool head from USA
-VForce 2 reed cage
-HPI programmable ignition.
-41 Keihin PWK from Sudco
-CPI sand pipe (measurements in the image below)

I want to share the basic data of this engine:
https://i.postimg.cc/KcJf5gtC/Captura.png (https://postimg.cc/yW301xQT)

https://i.postimg.cc/NMHX8601/Captura2.png (https://postimages.org/)

https://i.postimg.cc/3NQvtkyz/Captura3.png (https://postimages.org/)

https://i.postimg.cc/RVhRpVRh/Captura4.png (https://postimages.org/)

https://i.postimg.cc/sgZJy6bR/Captura5.png (https://postimages.org/)

https://i.postimg.cc/xdD3dGSN/Captura6.png (https://postimages.org/)

https://i.postimg.cc/xdvyNk0x/Captura7.png (https://postimg.cc/yJNSw83c)

https://i.postimg.cc/MKLYC2PD/Captura8.png (https://postimages.org/)

https://i.postimg.cc/nzVMB93T/Captura9.png (https://postimg.cc/NyVgwFqr)

With all this things the real rwhp curve and the EngMod2t simulation are shown below

https://i.postimg.cc/Ls9hvht0/CR500.png (https://postimages.org/)

https://i.postimg.cc/HLF4Vf82/Captura.png (https://postimages.org/)

You can see the extrange dip in the curve around 8200 rpm. The same effect can be observed in the 2:00 minute in this bike from Kaplan America with similar tuning... My question is about the general geometry in this "drag" pipe and how do you improve this engine? I am not discard build a new custom pipe but I am afraid about the harming effect in all the curves presents in a MX exhaust

https://www.youtube.com/watch?v=EEn1oy-rg30&t=107s
https://i.postimg.cc/fRnNfLnn/cpi-pipe.jpg (https://postimages.org/)

[jonny quest]

P12, that diffuser is way too short.

[Wos]

P12paplof,

The stock cr 500 has a ridiculous head Design...squish gap nearly 3 mm...area 60 percent...

Thats what honda did to keep a 500 2 stroke rideable :nya:

In your dyno chart there is a powerdip short after 4000 where retard drops... in my opinion it drops to early...
Ignition timing at peak power is little to high...bad for max power and overev...better do 15 degree at peak and drop steeper after peak...



Change head to more modern values as you did...keep compression low and do your own ignition curve

Grüße Wolfgang

[wobbly]

Skako - way too much of your sim is completely wrong to take away any useable information from the results.
Here is a quick list of the issues.
First 15 Bar bmep @10800 = 18 Hp is basically impossible at that rpm in a 50cc piston port engine.
The 70% diffuser is way too long and a 2.1* header will never work.
A CE of 0.95 and a 12:1 A/F is impossible on 95 pump gas.
A 76% chordal Exhaust port with a flat timing edge is impossible = instant ring destruction.
The Intake is over 2X too long to get any useable tuning and has no end correction,
4* of ignition timing at peak power will never make any power.
Pipe wall temp is way too low.
MSV @ 28.7 M/s is way too low.

I could rework the whole thing but of course that is expensive and im already way too busy, even on holiday.

[flyonly]

Woobly

For max hp from a 50cc would it be reed or disc valve?


Sent from my iPhone using Tapatalk

[wobbly]

For a while there I thought the development of reeds was beginning to approach the power capability of a Rotary Valve,
But then Neil Hintz blew it all out of the water with is sliding Gibb concept.
This now makes the Rotary impossible to even get close to , without all the development needed to make 24/7 a reality.

[skako]

Wobbly, thanks for your comments. It will be a good guideline for me for changes in the new sim-model with bmep around 10 bar.

[lodgernz]

354205

I often receive pistons with these circlips, and I never use them, as I've heard that the tags can break off in an engine.

Is this just an old wives' tale, or has anyone actually had this problem?

This type would be much easier to fit than the preferred pain-in-the-arse un-tagged type.

[husaberg]

354205

I often receive pistons with these circlips, and I never use them, as I've heard that the tags can break off in an engine.

Is this just an old wives' tale, or has anyone actually had this problem?

This type would be much easier to fit than the preferred pain-in-the-arse un-tagged type.

This might be more of a widows tale.
I have never seen a modern MX or GP bike with tailed circlips so i think there might be something in it.
this was bell.

Another problem with standard replacement pistons is that many do not have any
circlip extractor slots. This means that only tail-type wire circlips can be used and
unfortunately this type of circlip wrecks engines. The constant rubbing of the gudgeon
pin against the circlip wears through the tail, allowing it to drop into the cylinder,
scoring the bore and possibly seizing the motor. If tail-type circlips are replaced
regularly, say after every second race meeting, this kind of damage can be avoided

A better solution is to machine extractor slots into the piston so that tailless
circlips (or tail-type circlips with the tail cut off) can be fitted (FIGURE 7.7). The slot
need only be '/sin. wide to allow a small electrical screwdriver or the point of a scriber
to fit under the circlip so that it can be flicked out. It should be cut in the position
shown, using a small round key file or a '/sin. dia. mounted grinding tip. Do not use a
hacksaw blade or three cornered file to make the extractor slot, as the abrupt corner
will form a stress point and eventually cause the piston to crack.

[wobbly]

P12 re the 500 sim , some pointers.
The Exhaust duct is 90 long , but where is the slip joint - its not in the pipe numbers before the header where it should be.
The reeds are miles too thick with a 1st Mode @ 12193 rpm.
12.5:1 A/F on Premium is impossible and also gives way too high gas temp - and that leads to unrealistically low pipe wall temps needed.
The pipe itself is a complete abortion , not even remotely suitable for anything that works even 1/2 way properly.
Having the Blowdown capability @ 83 Hp and the Transfers @ 95 Hp is always going to create big anomalies in the sim/dyno results , even more so as the
reed ports are down @ 65 Hp
You should , if everything is close to ideal have 15* timing @ peak power , this has it at 8200 , so alot more than necessary at peak.
But you can probably get away with this due to the big STA anomalies , the shit pipe design and no compression to speak of.

[lodgernz]

Yeah, thanks Husa, pretty much what I've been told.

[p12palof]

P12paplof,

The stock cr 500 has a ridiculous head Design...squish gap nearly 3 mm...area 60 percent...

Thats what honda did to keep a 500 2 stroke rideable :nya:

In your dyno chart there is a powerdip short after 4000 where retard drops... in my opinion it drops to early...
Ignition timing at peak power is little to high...bad for max power and overev...better do 15 degree at peak and drop steeper after peak...



Change head to more modern values as you did...keep compression low and do your own ignition curve

Grüße Wolfgang

Thanks for the reply Wolfgang. You are correct, the stock CR500 head is a disaster from the point of view of theorical design... When I tuned this engine in 2008 the first head that I put in the bike was the '86 version with less squish area and higher compression. The bike run hard in mid with a noticeable better response in comparison with the stock '94 head... But the majority of Honda CR comes with sheet metal head gasket and I experienced gas leakage problems. This is what I changed to Cool Head. This head has larger volume (60cc) and lower squish area with tighter clearance. I built another toroidal custom head with 1.2mm squish gap, 55cc volume

The result is always the same, with higher compression, you can feel the extra torque and better response in partial throttle openings, but in the dyno, the curves are always the same. You can´t feel noticeable differences at WOT

https://i.postimg.cc/c1wYw0w5/IMG-20240104-123020.jpg (https://postimages.org/)


P12 re the 500 sim , some pointers.
The Exhaust duct is 90 long , but where is the slip joint - its not in the pipe numbers before the header where it should be.
The reeds are miles too thick with a 1st Mode @ 12193 rpm.
12.5:1 A/F on Premium is impossible and also gives way too high gas temp - and that leads to unrealistically low pipe wall temps needed.
The pipe itself is a complete abortion , not even remotely suitable for anything that works even 1/2 way properly.
Having the Blowdown capability @ 83 Hp and the Transfers @ 95 Hp is always going to create big anomalies in the sim/dyno results , even more so as the
reed ports are down @ 65 Hp
You should , if everything is close to ideal have 15* timing @ peak power , this has it at 8200 , so alot more than necessary at peak.
But you can probably get away with this due to the big STA anomalies , the shit pipe design and no compression to speak of.

Thanks for your time to respond, Wobbly, I appreciate so much your expert opinion. Talking about the exhaust duct, I "included" in the exhaust port menu from Dat2T the spigot, It has a CNC blend round to oval shape. I´ll correct it in the next simulation data. At the time of dyno test, I´ll test this bike with a 47mm diameter equivalent area restrictor but then I tested in the road this same spigot grinded to 51mm diameter and I felt a slight improvement in top end and overrev power... I´ll need to test this mod in dyno. I attached the pics for the new CNC spigot with o rings. I will work on the rest of the simulation points that you indicate.

https://i.postimg.cc/RZVnkt8j/IMG-20240106-114752.jpg (https://postimg.cc/XpmJFrn8)

https://i.postimg.cc/dVHTw1cD/IMG-20240106-114756.jpg (https://postimg.cc/5Xztmf0M)

About the ignition curve, I post the best curve that I could obtain in the dyno. In low end more advance does not give me more hp, but in top end, this bike wants higher advances than the ideals.

https://i.postimg.cc/mkj6rMS0/Dibujo.png (https://postimg.cc/hQJ0yX6r)

And 2 pics from the reed cage. After years here are the Vforce 2 surface... A mix from lack of blowdown, a little higher transfers and carburetor size restriction causing hot gases return to crankcase?

https://i.postimg.cc/HsmMtRtW/IMG-20231229-WA0031.jpg (https://postimg.cc/14W4mWTb)

https://i.postimg.cc/65hvbcHr/IMG-20231229-WA0033.jpg (https://postimg.cc/qzzqzsHq)

[Haufen]

Thanks. Btw, the first link says


What is the reason behind the dual angle kinked negative squish area? Did KTM have pistons with a corresponding shape, or a bowl, too?

354188


Comments on the KTM head, anyone?

[p12palof]

Comments on the KTM head, anyone?

I´m not an expert in GP engines but I know that there is "semi flat" pistons for TM KZ karts, consisting in flat top, with a large bevel 4º angle in the piston crown / edge. It seems that this KTM GP head copies this semi-flat piston shape....

Below the VHM piston for KZ engines

https://i.postimg.cc/QCBbvkkb/Captura.png (https://postimages.org/)

[wobbly]

Speaking of Bartol copying everything - I showed him my semi flat top design for the BSL500 when he was still running the Yamaha 125GP team.
Funny how that made it into the KTM GP engine.

And when you can wind in alot of advance , this immediately indicates that the dynamic compression ( dictated by the engines efficiency ) is low to begin with
As I said a crap pipe and no compression.

[husaberg]

pretty sure the A kit stuff for the NX4 was a flat top design
as well the works 98 and 250 twin crank and the 2001 single crank version
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=337759&d=1532854225

that said thaose pics of the KTM a couple appear to be tordial.
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=309436&d=1425089721

these TZ125 appear flat top
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=302331&d=1411727294

That said Greeves had flat top pistons in the 60's pretty sure Herman Meiier had them in the 50's

[Haufen]

For me, that (particular) head in the picture is not a semi flat but looks something like this:

354206
I drew a half section and used three colors in the squish area to highlight what I mean

[Gradella23]

Speaking of Bartol copying everything - I showed him my semi flat top design for the BSL500 when he was still running the Yamaha 125GP team.
Funny how that made it into the KTM GP engine.

And when you can wind in alot of advance , this immediately indicates that the dynamic compression ( dictated by the engines efficiency ) is low to begin with
As I said a crap pipe and no compression.

multiple people in Italy say that KTM had even more power than an Rsa (56hp) but with less range so they were still slower. If the engine was an Honda copy, how could they match Aprilia's power? wasn't the Honda engine around 50hp?
I'm a little dubious tbh but this is what i've heard...

and another little question, if you can speak publicly about it: when you tried the reduced exit area on Kz engines, how much did you gain? how much was the final port height, something like 28mm? i remember your welded cylinder pics here. the new tm R2 black has the aux ducts "ears" on the exhaust flange but this in fact increases the exit cross section, so i don't know if they're going after your theory

[aljaxon]

mickey mouse alert.
in my latest pipe design ive got zero over rev. 32 68 header diffuser. pipe pulls great below peak power. miles better than previous design. but ive overdone the lack of over rev. will a shorter belly longer rear cone help?

ive gone a bit mad 2 stage header 3 stage diffuser and 3 stage rear cone, each getting sharper. belly might be a bit long. 90mm in a 992mm pipe. and ive built in a restrictor end of rear cone with a short 10 degree diverging cone to my stinger.

with 32 68 am i fighting a losing battle trying to get back over rev unless i lengthen the rear cone belly which then reduces the peak rpm. or like i said earlier shorten belly and lengthen rear cone.

im prepared to pay for this lunch.

https://www.flickr.com/photos/157464900@N04/53449586859/sizes/c/

[aljaxon]

https://live.staticflickr.com/65535/53449586859_4d91e2cb8f_c.jpg

[wobbly]

Al , I sent a DM so you can pay for lunch , just for starters you have a THREE cone header and why do you want a diffuser after the rear cone - absolutely wrong.

Gradella , there is alot I cannot say about the R2 on here , but alot of work inside the duct was tested at the factory that I did not do.
Yes , the duct exit area is a bit too big , and the ears transition in the spigot is not elegant CNC programming at all - it could be done way better.
Here is my hand prototype.

And regarding Mr Bartol - yes he did copy and take credit for others work , but he also had access to a Czech flow analyzer that as I said other top class tuners regarded
as a seriously good tool.
Jan didnt like it , others did , so maybe Harold understood enough from its results to achieve serious power.
But then again , he simply copied an A Kit Honda exhaust , and even Witteveens attempt that Jan was forced to engineer around , was a far better pipe.

[jamathi]

Al , I sent a DM so you can pay for lunch , just for starters you have a THREE cone header and why do you want a diffuser after the rear cone - absolutely wrong.

Gradella , there is alot I cannot say about the R2 on here , but alot of work inside the duct was tested at the factory that I did not do.
Yes , the duct exit area is a bit too big , and the ears transition in the spigot is not elegant CNC programming at all - it could be done way better.
Here is my hand prototype.

And regarding Mr Bartol - yes he did copy and take credit for others work , but he also had access to a Czech flow analyzer that as I said other top class tuners regarded
as a seriously good tool.
Jan didnt like it , others did , so maybe Harold understood enough from its results to achieve serious power.
But then again , he simply copied an A Kit Honda exhaust , and even Witteveens attempt that Jan was forced to engineer around , was a far better pipe.

At Jamathi we made such a Jante flow machine ourselves.
After some time we concluded that it was useless!!!
Jante was an East-German who invented this system. We still used it at Bultaco

[wobbly]

Jan , the later Czech visualization machine that Yamaha and Bartol used was CNC controlled and insanely expensive.
It showed the in cylinder flow vectors ( speed and direction ) on a computer screen in varying colors.
Bud Askland the Roberts actual test engineer , was seriously impressed , quite a feat for a guy who absolutely knew everything there was to know ( his words not mine ).

My boss was a NZ multi millionaire , but sadly after all my begging , even he thought the E80,000 was a stretch too far.
This was ( and is ) seriously trick use of digital technology - I can certainly believe that just maybe Harold learned enough to make a better mousetrap , but he was still
constrained by using copied technology he had no understanding of at all.

[husaberg]

multiple people in Italy say that KTM had even more power than an Rsa (56hp) but with less range so they were still slower. If the engine was an Honda copy, how could they match Aprilia's power? wasn't the Honda engine around 50hp?
I'm a little dubious tbh but this is what i've heard...

and another little question, if you can speak publicly about it: when you tried the reduced exit area on Kz engines, how much did you gain? how much was the final port height, something like 28mm? i remember your welded cylinder pics here. the new tm R2 black has the aux ducts "ears" on the exhaust flange but this in fact increases the exit cross section, so i don't know if they're going after your theory

Hi years ago Frits posted the Debri vs Aprilia RSA graph.
pretty sure even with the same cylinder the red valve would cost at least 4-5 hp on a 125 gp bike.
Frits had said Jan had a play after this test and got a few more HP from the copy of the Kit Honda.


I must have a stack of Derbi drawings somewhere back in Holland but don't recall every detail and maybe some mods were never captured; Jan had a knack of modifying and testing first, and having the mods drawn afterwards. But it's safe to assume that Jan tested every mod you can think of, and then some.
Besides, you can ask Jan directly; he is looking in from time to time.


A technical explanation? Nah, too much to do today. But since you were kind enough to post that picture of your sex six sisters, I will show some curves of my own.
When Jan Thiel went to Derbi to design the bike we now know as the Aprilia RSA125, he encountered the 125 cc reed valve Derbi ridden by Lorenzo the previous season. Jan played around with the reed valver as well, because he wanted to find out the differences between reed valve and disk valve power. He managed to extract 2 HP more from the reed valver than anyone else had ever done before (never mind the fairy tales of reed valve 125s producing over 50 HP; those Horses must have been Shetland ponies, probably measured at the piston ring).
My graph shows the power curve for the Aprilia RSA, the Aprilia RSW and that best-ever reed valve Derbi. It's not quite in the same league as the rotaries, hmm?

EDIT: Shame on me; I discovered that I posted a wrong graph (and I do not have the correct one at hand here in Holland). Power curve DERBILOR shows the reed valve Derbi as Lorenzo rode it. After Jan finished playing with it, it had 49 HP. Still, the best-ever disk valver produced 10 % more power than the best-ever reed valver.
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=261462&d=1333621581
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=261462&d=1333621581

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=350632&d=1644312008
click on here to go to graph as the device i am ob will not play ball



Yes, of course it was....

Thanks for your answers Jan, Can you confirm what mods he made to the reed Derbi as frits Alluded to above to boost its HP
or did you just put your own cylinder on it?

[F5 Dave]

So I was idly thinking. We know that Rotax made the road engine and the 256 kart engine. What involvement did they have in the GP years of the 3 classes and when did it diverge?

Was reading a classic race magazine today that stated the RS500 had a RAVE valve which was electronic but a Rotax name I thought.

Same magazine had Holden winning NZ 250 on a 256 in early 80s which is in a mates spare bedroom about 4km from here.

[husaberg]

So I was idly thinking. We know that Rotax made the road engine and the 256 kart engine. What involvement did they have in the GP years of the 3 classes and when did it diverge?

Was reading a classic race magazine today that stated the RS500 had a RAVE valve which was electronic but a Rotax name I thought.

Same magazine had Holden winning NZ 250 on a 256 in early 80s which is in a mates spare bedroom about 4km from here.

here is the early Aprilia story.
and next post
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130170725#post1130170725

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130170848#post1130170848

i also posted about the other chassis makers that used Rotax engines and there relationship with them here.
https://www.kiwibiker.co.nz/forums/showthread.php/145224-Race-chassis?p=1130222016&highlight=rotax+emc+waddon#post1130222016

But it would be great to hear from Jan and Frits....

[aljaxon]

Al , I sent a DM so you can pay for lunch , just for starters you have a THREE cone header and why do you want a diffuser after the rear cone - absolutely wrong.



the first part of the header ive drawn is the wobbly duct from piston to end of duct. 2 x bore with 1.5 x converging and 0.5 x bore diverging.

the last diffuser after rear cone is a restrictor i saw on here. with a 10 degree cone after it.
https://live.staticflickr.com/65535/53450961590_71f1ebd22b_c.jpg

i had previously been inserting the stinger inside the pipe as far as the belly but can imagine a strange object inside the cone could hinder the waves somehow.
saw that thought id try it. is it a bad idea?
just tried sending you a dm but the dm factory at my end is broken. it wont allow me to type anything. i havent got engmod or indeed any software.

WARNING - to anyone like me who trawled though this thread stealing pipe designs these next designs are not very good.
ive made these different end sections to try just to see what they do and if they behave as they should.
https://live.staticflickr.com/65535/53450693443_3f9fe3c302_c.jpg

no need to go into depth on my query, im guessing you havent enough time for your own projects never mind for the likes of me asking questions from all directions. any info or judgement you care to pass on would be much appreciated. i should be doing other stuff myself but there is something about making a pipe as if you are bringing something to life. but like anything im guessing the novelty will soon wear off.

[Wos]

@12palof

Your cr 500 ...what is your purpose you are aiming for?

A 500 cc will never reve easily high... especially if you have less blowdown as needed


21 degree on the bottom rpm is possible as you increased the msv of quish

You set ignition to 15 degree at 8000 ...realy?
Cant beliefe 8000 is peak power at old reed 500cc engine

My guess would be peak much under 8000...

To much advance after max power / running out of breath surly kills every free reving..

One way for first shot to set timing at peak power is to look where is peak in datasheet from original bike...

Your exhaust duct / flange...are there steps inside to the header ?


Edit...please google for "cr500 vhm dyno tests"

Peak of cr500 is about 5500... and "on pipe" is lower than 4000...

Have made a quick and dirty ignition curve that should fit to cr500 ...only for a first shot ;) and maybe your next dyno run..i bet fits better...please let me know

If you need the tunebox file...let me know too ;)

Grüße Wolfgang

[Gradella23]

Al , I sent a DM so you can pay for lunch , just for starters you have a THREE cone header and why do you want a diffuser after the rear cone - absolutely wrong.

Gradella , there is alot I cannot say about the R2 on here , but alot of work inside the duct was tested at the factory that I did not do.
Yes , the duct exit area is a bit too big , and the ears transition in the spigot is not elegant CNC programming at all - it could be done way better.
Here is my hand prototype.

And regarding Mr Bartol - yes he did copy and take credit for others work , but he also had access to a Czech flow analyzer that as I said other top class tuners regarded
as a seriously good tool.
Jan didnt like it , others did , so maybe Harold understood enough from its results to achieve serious power.
But then again , he simply copied an A Kit Honda exhaust , and even Witteveens attempt that Jan was forced to engineer around , was a far better pipe.

thanks wob. Is this pic the welded one with reduced cross section or just a standard one with ears added?
where should we draw the line in terms of cross section% at the cylinder exit with a Kz like long duct (around 60mm)? From your tests, is it still worth to go 75% even with a lot less lenght?

[gamma500]

Kevin Cameron article about 2t scavenging and the Jante flow machine:

https://www.cycleworld.com/searching-for-sense-among-different-two-stroke-scavenging-schemes/

Edit: another one

https://www.cycleworld.com/colliding-streams-versus-flow-symmetry/

[wobbly]

Al , I still dont get it - the diameters are 25/30/36.3/41.2 , where is the converging duct , and where is the short divergent transition section before the header?
And the nozzle with diverging cone at the stinger entry has been superseded by a short section with a step - more power.
The stinger up inside has no real effect on power - just makes it alot quieter.
To even begin a new design we need the area and timing of the port , the duct length and desired peak power rpm.

GRAD - the pic shows my welded and CNC cut duct with 75% at the cylinder face.
If you measure an R2 Black you will find the smallest duct height is about 2/3 of its length from the port, but I didnt tell you that.

[Haufen]

I think there may be a bug in the attachment, wob :drinknsin


Did I see something that is not there in reality on the KTM head, or is it just that nobody has an idea about the strange shape of the squish?

[aljaxon]

apologies, my error in not putting dims on the first bit of the header which is part of the cylinder duct that ive altered to follow the 75% duct convergence then back to 100%.

https://live.staticflickr.com/65535/53452695027_fe99524a76_c.jpg

47mm bore so that first bit without a measure bit was my duct 94mm long. amended in the pic above

port area is 491mmsq which is 25mm diameter equivalent. so 75% or 491 is 441.8 which gives diameter of 23.8. (narrowest bit of wobbly duct. then short length of 23.5mm back to the 25mm. which is where the header proper starts even though ive used the initial 94mm as part of the header length.

and ive just blown my head off thinking that hand drawn sketch was for me and the stepped stinger and trying to fathom it out lol.

been a long day for me trying to understand the instructions on one of those chinese diesel heaters.

[aljaxon]

ive got 180 degrees ex duration, i wanted peak at 8800 and i worked that out to be 916mm long. im used to working with small aircooled motors and 1mm mild steel and find i usually get the tuned length not far off if i use 509 as my speed of sound. (working backwards from a dyno read out.)

i tried 0.8mm mild steel this time and i dont know if its thrown things because my motor just wont rev past 8500.
with another pipe it revs to 10krpm and that one also has the cooling vanes on the first converging part of the duct.

it could be the long belly?

just for kicks i did a comparison speedo video. almost better than a dyno. i tried to change gear at the same revs each video but the tacho is a bit wayward.
ive been done in my van by dash cam twice in the last 2 years. dunno if that is a thing in nz? my footage even got shown on a local tv's program about crap driving.

so thats why i blanked it out because there was some highly iregular traffic negotiation on show.

for anyone whos bothered heres the video

for anyone whos bothered heres the video

the latest pipe is on the left and you can see the massive improvement in accel in the rev range i wanted.
ive since geared it up to gain 5 more mph and its still faster accel. so its not all bad news.

[husaberg]

Did I see something that is not there in reality on the KTM head, or is it just that nobody has an idea about the strange shape of the squish?

Oddly the for me pic you posted didnt seem to come from the pic i posted?
oh, it was out of the album.
on the colours and areas of your pic i thought it was a insert of two different alloys?
but that last one looks odd?

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=309438&d=1425089725
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=309441&d=1425089731
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=309437&d=1425089723

[Haufen]

but that last one looks odd?

Yes, I am wondering only about the last one. The others seem fine / normal to me.

On the strange head, there seems to have been detonation on the second / middle (yellow) part of the squish. Or maybe there was contact contact after the engine had sucked some sand / dirt / broken off pieces etc.
354220

[husaberg]

Yes, I am wondering only about the last one. The others seem fine / normal to me.

On the strange head, there seems to have been detonation on the second / middle (yellow) part of the squish. Or maybe there was contact contact after the engine had sucked some sand / dirt / broken off pieces etc.
354220



that last outer bit seems to be about the same width as the radiused edge of the flat top.

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=309445&d=1425089738

Oddly the skirt profile appears to be very different from the sculptured skirt of the NSR500 and 250's

nsr500
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=316038&d=1443001390

Bartol KTM
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=309446&d=1425089740

oh i see why

KTM
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=309432&thumb=1&d=1615035702

NSR500
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=316030&d=1443001378https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=316037&d=1443001389



RS125 second on left looks sandcast?
or vapour blasted?
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=307120&d=1419622907https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=302750&d=1411967058https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=302749&thumb=1&d=1615035328
this one has a PV but i guess could be 250



This one below was in my album not sure what RS125 they are nx4 i think according to the name....
one looks like it has been dingle berried .the other au natural

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301530&d=1411382829https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301525&d=1411382829

What was this pipe Frits?
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301482&d=1411381933

[husaberg]

I did find these pics not sure what they are as the don't appear to be named but kind of look tz ish
https://www.daemo.de/Race/HH125.html
https://www.daemo.de/Race/Stenger2.jpghttps://www.daemo.de/Race/Stenger.jpg

On the same site one for the fans of Honda 50's



.......
this one is another disc valve one
https://www.daemo.de/Race/Rob/Motor.jpghttps://www.daemo.de/Race/Rob/Motorinnen1.jpg

https://www.daemo.de/Race/Honda50.html

[jonny quest]

Who's going to buy one and cast their own cylinders?

https://www.ebay.com/itm/364191011304?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=7LsJgfPXTwS&sssrc=4429486&ssuid=LrJx0MZsQLq&var=&widget_ver=artemis&media=COPY

[Frits Overmars]

What was this pipe Frits?
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301482&d=1411381933..........
354221

[skako]

Hi, Frits
is there a link somewhere to explain these abbreviations Lt, Lsz, iso, nL, nD, nT.
I suspect they are related to the variable pipe length and resonant rpm.

[Frits Overmars]

Hi, Frits
is there a link somewhere to explain these abbreviations Lt, Lsz, iso, nL, nD, nT. I suspect they are related to the variable pipe length and resonant rpm.Not a link as such, but I will try to explain if you promise to refrain from asking follow-up questions; at the moment I am too involved in design work to formulate answers.
Lmax is a no-brainer: from the exhaust port upper timing edge to the throat of the end cone restrictor.
The whole end cone, from its maximum diameter to its minimum diameter, plays a role in reflecting the stuffing pulse. Somewhere along the end cone(s) is the 'center of gravity' as it were, of this reflection. Lt gives the position of this center.
Lsz is a percentage of Lt; it does for the suction pulse what Lt does for the stuffing pulse. I've found that around 0,425 is optimal
iso represents the rate of temperature loss from the pipe to the outside world. The default value is 1. But as an example, a boat engine that wets its pipe with a rooster tail of water can drop its iso to 0.8.
nL is the optimum rpm for wave resonance.
nD is the optimum rpm for Helmholtz resonance.This value is strongly dependent on the header diameters.
nT gives the optimum value for the end cone restrictor. However, for you guys I recommend using the restrictor diameter D5 calculation in my simple FOS exhaust concept below.
354222

[skako]

thank you Frits :)

[wobbly]

Last November I ordered the English version of the Jan Thiel book, this had not arrived by end Dec and NL Post had no tracking data for it.
So I asked Jans friend who is doing the postage to look into it , and said as nothing had been scanned he would immediately send another.
Anyway , unbelievably both books arrived today , the first I opened and now cant put down , the other is still sealed in its envelope.
I promised to pay for the second book whenever it arrived , so in good faith Im offering it here to a NZ address for what it cost me.
If you want it ,DM me and it will be on the way.

[jamathi]

Last November I ordered the English version of the Jan Thiel book, this had not arrived by end Dec and NL Post had no tracking data for it.
So I asked Jans friend who is doing the postage to look into it , and said as nothing had been scanned he would immediately send another.
Anyway , unbelievably both books arrived today , the first I opened and now cant put down , the other is still sealed in its envelope.
I promised to pay for the second book whenever it arrived , so in good faith Im offering it here to a NZ address for what it cost me.
If you want it ,DM me and it will be on the way.

I am happy it finally arrived, hope yo like it!!!

[F5 Dave]

Pm sent Wob.

[JanBros]

@ Jan : shame about the last 250 WC lost to Aoyama; 50 titles sounds so much better than 49. or were you already retired and it wouldn't count ?

[p12palof]

@12palof

Your cr 500 ...what is your purpose you are aiming for?

A 500 cc will never reve easily high... especially if you have less blowdown as needed


21 degree on the bottom rpm is possible as you increased the msv of quish

You set ignition to 15 degree at 8000 ...realy?
Cant beliefe 8000 is peak power at old reed 500cc engine

My guess would be peak much under 8000...

To much advance after max power / running out of breath surly kills every free reving..

One way for first shot to set timing at peak power is to look where is peak in datasheet from original bike...

Your exhaust duct / flange...are there steps inside to the header ?


Edit...please google for "cr500 vhm dyno tests"

Peak of cr500 is about 5500... and "on pipe" is lower than 4000...

Have made a quick and dirty ignition curve that should fit to cr500 ...only for a first shot ;) and maybe your next dyno run..i bet fits better...please let me know

If you need the tunebox file...let me know too ;)

Grüße Wolfgang

Hi Wolfgang, thanks for the help. My CR500 is tuned. That´s the reason because it´s peak around 7800 rpm. Stock it´s peak around 5500-6000. The stock timing is around 178/122 and actually in my bike is 192/126. The CPI exhaust was "intended" for drag races in dunes... with the objective of maximum peak power only in mind. This bike is not confortable in stock condition. Tuned is also uncomfortable :lol: but at least it has more revving capability.

My objective is to improve the shape of the power curve, maintaining the revving capability. I will test your ignition curve, as soon as I put the bike on dyno. At this moment the bike is dissambled for maintenance.

[wobbly]

Thanks for the messages guys , the book sold in about 30 seconds.

[Wos]

Hi Wolfgang, thanks for the help. My CR500 is tuned. That´s the reason because it´s peak around 7800 rpm. Stock it´s peak around 5500-6000. The stock timing is around 178/122 and actually in my bike is 192/126. The CPI exhaust was "intended" for drag races in dunes... with the objective of maximum peak power only in mind. This bike is not confortable in stock condition. Tuned is also uncomfortable :lol: but at least it has more revving capability.

My objective is to improve the shape of the power curve, maintaining the revving capability. I will test your ignition curve, as soon as I put the bike on dyno. At this moment the bike is dissambled for maintenance.

Ok... you have blowdown enough...then my ignition is not helpfull

But set 15 degree on your measured peak...not later...and do dyno

Then do a dyno test with setting 15 degree before last measured peak...lets say 1000 earlier... and you get a new peak...can compare both ...see whats better for overev ;)

Overev can also be maintained by how steep and deep your falling of timing after peak is...secret there is to produce high exhaust gas/ pipe temperatur within a given length of pipe..

Have nice dyno runs! �� and Let us know

Grüße Wolfgang

[jamathi]

@ Jan : shame about the last 250 WC lost to Aoyama; 50 titles sounds so much better than 49. or were you already retired and it wouldn't count ?

I was already retired, in 2007.
Unfortunately Simoncelli broke his wrist 2 weeks before the season started...

[wobbly]

And as I heard it there were already several " engineers " at Aprilia who were intent on doing R&D on Jans engines after he retired , working real hard to make it slower - after all what the hell did he know.

[katinas]

You can see the extrange dip in the curve around 8200 rpm. The same effect can be observed in the 2:00 minute in this bike from Kaplan America with similar tuning...



The dip in this graph similarly replicates the CR 250 graphs with reed intake into the cylinder type. It is partly related to the Honda type of Boyesen side intake ports.
1991 Honda factory team prepare CR RC 250 for domestic championship with more power extracted from std cylinder at higher revs, to compensate looses with hydrostatic transmission. They cut off wall between B and intake to open flow through side ports directly to B (add photo) transfers . This eliminate usual dip at 8000 rpm, but slightly lost at 6500 rpm even with HPP valve.
Add other photos of factoryHonda NS 500 and RS 500 difference of side intake ports . Last is Hans Hummel type for RS 500.
Hummel s 7 transfers type cylinders have a good mid range power without exhaust power valves and often used for sidecars on TZ crankcase.

[jamathi]

And as I heard it there were already several " engineers " at Aprilia who were intent on doing R&D on Jans engines after he retired , working real hard to make it slower - after all what the hell did he know.

The crankcase volume was regarded as too big, I Don't know their results.
Also a honda type exhaust port was tried: 1.5HP less...
To make place for this exhaust port the transfers had to be narrowed which costs power.
When I arrived at DERBI the very best cylinder gave 47.5HP
But most were anoud 46-46.5
So much for Czech flow benches....
Bartol's trick was to pay some money to some dishonest mechanics who then brought him the latest Honda cylinders
And copy them immediadiately.

[philou]

https://youtu.be/XTCWU78CjBw?si=wxrD2Ip7nwxj1bBm

[Frits Overmars]

Thanks Philou. I always enjoy watching videos with Gabriele Gnani.
I picked up some Italian along the way but if you are into motorcycle racing, you may get the picture even if the language is new to you.
(Wob, I think it would be a great way for you to brush up on the lingo).
By the way Philou, your link https://www.youtube.com/watch?v=XTCWU78CjBw shows part 2.
Part 1 is here: https://www.youtube.com/watch?v=3tJupBvcIQs
And further below there are a number of other Gnani links.

Two things struck me while whatching part 2.
The first thing was Gabriele talking about his unique ultrafast shifting gearbox, a 'cambio a crociera scorrevole'.
It's a great box but unique it is not; Jan Thiel built such a rod & pawl gearbox in 1964, Gnanis year of birth if I'm not mistaken.
The second thing I noticed, was Gabrieles cell phone. You gotta love this:
354242

more Gnani links:

dyno:

https://www.youtube.com/watch?v=Lxq-9tPxWc8

2021:

(https://www.youtube.com/watch?v=Lxq-9tPxWc8)https://youtu.be/xJPYXG1oGl4

2016:

https://www.youtube.com/watch?v=ONS0elyCX8s&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=BEeMHT0E1m8&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=4Rh6J6stfMQ&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=7ys5PfS___g&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=i_VWzz7HMn0&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=mwX8qCTT2nQ&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=c5Df3ICSy48&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=EgynmhCn2wM&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=LCm5ZCyy4Gc&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=irw9-pK-tT0&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=I8aZR-c1V2A&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=wdDPvVVrVBM&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=e_j5Yjm7-0E&ab_channel=cristiancorticchia


2017:

https://www.youtube.com/watch?v=_WxgXOe5ma4&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=wQmrG8u_ijE&t=147s&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=cbSracHHIvw&ab_channel=cristiancorticchia

https://www.youtube.com/watch?v=SGjpDo6yp2U&ab_channel=cristiancorticchia

[jamathi]

Al , I sent a DM so you can pay for lunch , just for starters you have a THREE cone header and why do you want a diffuser after the rear cone - absolutely wrong.

Gradella , there is alot I cannot say about the R2 on here , but alot of work inside the duct was tested at the factory that I did not do.
Yes , the duct exit area is a bit too big , and the ears transition in the spigot is not elegant CNC programming at all - it could be done way better.
Here is my hand prototype.

And regarding Mr Bartol - yes he did copy and take credit for others work , but he also had access to a Czech flow analyzer that as I said other top class tuners regarded
as a seriously good tool.
Jan didnt like it , others did , so maybe Harold understood enough from its results to achieve serious power.
But then again , he simply copied an A Kit Honda exhaust , and even Witteveens attempt that Jan was forced to engineer around , was a far better pipe.

The only serious power bartol gained was by copying Honda.

[Javier Ruda]

Hello Frits, I also love Gabriele Gnani passion when explaining the technical matters, and how he got altruistic help from a lot of people in his beginning.

Maybe you could clarify something he mentioned to the visitors. Literally he said that V-force type reeds are shit (“il V-force non va un cazzo“).

I think karts usually fit normal reed blocks and dirt bikes V-force type. Is there maybe more power from normal blocks and better control or response from V-force?

Another interesting link about Gnani:
https://youtu.be/xJPYXG1oGl4

[Frits Overmars]

Hello Frits, I also love Gabriele Gnani passion when explaining the technical matters, and how he got altruistic help from a lot of people in his beginning.
Maybe you could clarify something he mentioned to the visitors. Literally he said that V-force type reeds are shit (“il V-force non va un cazzo“).
I think karts usually fit normal reed blocks and dirt bikes V-force type. Is there maybe more power from normal blocks and better control or response from V-force?

Another interesting link about Gnani:
https://youtu.be/xJPYXG1oGl4Thank you for the link Javier (this video has English subtitles !)
I do not have sufficient experience with V-force reeds to answer your question but I'm sure Wobbly can.

[katinas]

Another interesting link about Gnani:
https://youtu.be/xJPYXG1oGl4

So nice to listen and read. "Taking less risk as you get older because you have less to lose" inspirational quote to race as long as possible.

[wobbly]

I only have a few documented real world experiences with VeeForce.
Fitst was many years ago when we had what was called 125 National Karts.
These had to be production MX motors , no race KZ types allowed.
I chose a TM125MX and spent months on the dyno dialing in the porting and pipe design.
Last thing to do was the reeds - it already had some trick Carbon Tech items in there I had tested with various thickness and backups.
So I bunged in a VF2 , the original screw together type that was designed for a CR125 or RS125 as the bolt pattern was identical, the only difference was the petal thickness.
Short story was that using the VF2 with thicker CR125 petals on the bottom Vee and RS 125 thinner ones on the top Vee along with the older ( shorter ) dead straight NX4 rubber manifold
that setup made damn near +2 Hp everywhere and +4 Hp at 12800 and won 4 straight NZ1 plates until the class was abandoned to KZ only.
The later VF3 and VF4 were never that good , were close - but still way better than anything I could conjure up from the TM reed block, no matter what petals or 3D printed stuffers I used.

The other tested scenario was for LC350 engines used in Post Classic race bikes.
When I did those only the VF4 for a Banshee were available - and eventually I gave in and bought some El Cheapo Chinesium copies that cost something idiotic like $25NZD each , free freight.
The slant eye copies were only different in that the petals were utter crap , but fitted with real VF replacements they worked perfectly and were reliable over many seasons of subsequent racing.
Back to back against any LC or Banshee reed I could find including Mossbarger and Boyesen replacements ,the VF4 in a racebike with 34mm or 35mm carbs were absolutely light years faster.
As close as it gets to any free lunch I have ever had.

The other projects were in 440 Champ Snow engines and lately in 500 Class Snow Dragracing. The big VeeForce is pretty much ubiquitous and a winner big time , but I am currently doing a Rotax 670
Rotary Valve project that will end up at 508cc ( overbore limit ) and will steal Niels sliding Gibbs. The big issue is that all the Rotaxes use the same valve size and means even with lots of weld/machining and oversize
carbon blades the ports on a twin are nowhere near on bore center - this looses alot of potential power - so even there the reed version might still be better.

[Javier Ruda]

Thank you Wobbly for the explanation! That is a lot of accumulated experience. Maybe Gnani’s engine has some design not favorable to V-force.

[F5 Dave]

As I've learnt from the dyno, you only have to have 1 mismatch and what should work better strangely doesn't. Every new combination needs testing, often with jetting and timing tweaks to reflect it in its proper light.

Goods sims probably circumnavigate some of this but beyond me. I'd bet entry errors account for a fair bit of non expected rear wheel hp going missing.

[husaberg]

I was most puzzled by what he meant by crucifix or cruciform gearbox is this a google mixup?
it was also odd he went reed valve when he was previously disc valve. on the 80s at least.

[Grumph]

I was most puzzled by what he meant by crucifix or cruciform gearbox is this a google mixup?
it was also odd he went reed valve when he was previously disc valve. on the 80s at least.

Rod through gearbox mainshaft pushes a piece out to lock a gear to the shaft. If it's a cross or cruciform shaped piece that's where the name comes from.

If it's a simple bar or a triangle shape you can call it something else. Maker's call. Similar box on early Lotus F1 cars was known as the queerbox. As previously discussed here.

[husaberg]

Rod through gearbox mainshaft pushes a piece out to lock a gear to the shaft. If it's a cross or cruciform shaped piece that's where the name comes from.

If it's a simple bar or a triangle shape you can call it something else. Maker's call. Similar box on early Lotus F1 cars was known as the queerbox. As previously discussed here.
Okay google might be needed
what it said on wiki was basically it inadvertantly led to the formation of Cosworth.


Unreliability
Initial servicing of the Queerbox was undertaken by Graham Hill, then a mechanic at Lotus. [iii] It was soon discovered that the final drive was reliably unreliable, with all examples having the hypoid crown wheel pinion of their final drives fail at around fifty miles, much less than a single race. When improved oils meant that they lasted barely long enough to compete, it was then found that the gearbox section was also unreliable, with a worn box becoming unable to select a gear and leaving drivers with "a box full of neutrals".[4]


The task of fixing the Queerbox's unreliability problems, fell to Keith Duckworth, a young Lotus engineer. He then fell out with Chapman, who would not support the cost of the fix that Duckworth felt was needed, leading to Duckworth leaving to set-up Cosworth with Mike Costin.

okay three vespas came up

they have an internal t selector

https://www.youtube.com/watch?v=m3xyb7vvxGo

https://www.youtube.com/watch?v=m3xyb7vvxGo.


Okay after a search

Close. Your description is spot-on; only that rod was in the output shaft. Lotus even tried this system in Formula 1.
There must be an English name for this type of gearbox but I don't know it. Do you?
Dutch: trekspiebak
German: Ziehkeilgetriebe
Italian: cambio a crociera scorrevole
Which also demonstrates which is the most economical language :p. Admitted: Italian is the best-sounding of these three.
Below the 9-speed Jamathi box of 1964 and the Bultaco box of 1977 when it had been mandatorily reduced to six speeds.
335704 335703 335702


By the way, the hideously expensive seamless-shift gearboxes in the Honda MotoGP works bikes are based on the same principle.
The clutch and the primary gearbox shaft of the Honda gearbox are quite conventional; they could have come out of an old Maico, Zündapp or Simson engine:
335712

All secrets are brought together in the secondary gearbox shaft:
335711

This secondary shaft looks like a cylinder from a security lock, with pawls that are operated from the inside by a rod that slides through the hollow gearbox shaft:
335709

The essence of the Honda box can be seen in the picture below. The pawls in the shaft connect and disconnect the gears to the shaft:
335710
In this drawing a tumbler Rao connects the gear to the shaft when the gear is rotating clockwise. And a tumbler Rbo is connecting the gear to the shaft when the gear is rotating anticlockwise. So in this drawing the gear is locked to the shaft.
The tumblers are governed from within the shaft via an axially moving rod.

Now if we perform an upshift, the shaft will need to rotate faster than the gear. Let us assume that the shaft is rotating clockwise. So we need to retract tumbler Rbo. Now the gear can still drive the shaft, but the shaft cannot drive the gear any more.

Next we engage tumbler Rao of the next gear, so it can also drive the shaft. Then we retract tumbler Rao of our original gear, so it can now freewheel in both directions. And finally we engage tumbler Rbo of the next gear so that it is now locked to the shaft.
That's all, folks: transporting torque from the gears to the shaft without interruption, both while shifting up and down.

Honda has filed patent applications for their seamless gearbox in Japan and the United States (patent applications 2010-203478 and US20110023639, respectively).
You can download the US patent document here: http://www.freepatentsonline.com/y2011/0023639.html


Rod and pawl is probably close enough - but I preferred the name the Lotus box earned - the Queerbox.

I suspect that the materials and machining technology of the time limited the torque and HP cpacity of that layout.
I have no doubt Honda have made it work with large amounts of Money...

[jamathi]

Rod through gearbox mainshaft pushes a piece out to lock a gear to the shaft. If it's a cross or cruciform shaped piece that's where the name comes from.

If it's a simple bar or a triangle shape you can call it something else. Maker's call. Similar box on early Lotus F1 cars was known as the queerbox. As previously discussed here.

I used this very successfully for many years: Jamathi, Piovaticci, Bultaco...

[Grumph]

I used this very successfully for many years: Jamathi, Piovaticci, Bultaco...

Well aware of this sir. Your development and use was argued very well by Frits when it was discussed on here several years back.

[Peljhan]

The same design as Tomos is using it.
If my memory is not at fault, one guy told me, patent was bought from Norton. In a time two companies cooperated.

Jan, I have a question for you. I read your book and at page 78 and 95, you are talking about repositioning primary gears from between cranks to side drive on a Bultaco 125cc 2c.
I wonder why is power gain so large? From 37 to 43hp you gained 6hp, that is 16% increase.
Thank you for answer.

The book was really nice reading I enjoyed. Thanks for taking your time to write it :not: :niceone:

[yatasaki]

My guess is two bearings less?

[Peljhan]

My guess is two bearings less?

My guess is one shaft, 2 bearings, one gear pair and maybe gears digging/splashing the oil. But 16% looks quite high number to me as gear pair loss is usually 1-3% of power. That's why I ask.

[jamathi]

The same design as Tomos is using it.
If my memory is not at fault, one guy told me, patent was bought from Norton. In a time two companies cooperated.

Jan, I have a question for you. I read your book and at page 78 and 95, you are talking about repositioning primary gears from between cranks to side drive on a Bultaco 125cc 2c.
I wonder why is power gain so large? From 37 to 43hp you gained 6hp, that is 16% increase.
Thank you for answer.

The book was really nice reading I enjoyed. Thanks for taking your time to write it :not: :niceone:

It was because the middle primary drive made an extra drive shaft necessary.
Eliminating this with the side primary drive also reversed crankshaft rotation.
I was amazed at the improvement!
All other 125's had side primary drive, so we followed!
My mistake was copying the Japanese engines which all had primary drive from the middle.....

[jamathi]

The same design as Tomos is using it.
If my memory is not at fault, one guy told me, patent was bought from Norton. In a time two companies cooperated.

Jan, I have a question for you. I read your book and at page 78 and 95, you are talking about repositioning primary gears from between cranks to side drive on a Bultaco 125cc 2c.
I wonder why is power gain so large? From 37 to 43hp you gained 6hp, that is 16% increase.
Thank you for answer.

The book was really nice reading I enjoyed. Thanks for taking your time to write it :not: :nice one:

My problem was that I followed Japanese practice of putting primary drive in the middle, which causes a big power loss.
Where this came from I don't know, probably MZ-Degner...
Jorg Moller discovered this when helping Jos Schurgers to build the Bridgestone 125-2
Using Bridgestone crankcases, they were practically 'obliged' to use side primary drive
And discovered that it went very well!!
So when Moller went to Morbidelli he made an engine with a side primary drive
It was a BIG success!
And I made a BIG MISTAKE, which cost me power for years to come.....

The book was written by an Italian, it brought me a lot of satisfaction, we did it together using 'SKYPE!
And it saved my life, because with the earnings we could pay a recent hospital bill.
Without it I would be dead now..........
I am very grateful to my friend Dolph van der Woude who distributes the books!!!!!!!!

[aljaxon]

...the nozzle with diverging cone at the stinger entry has been superseded by a short section with a step - more power.
.

are there any diagrams of this anywhere please? ive searched this thread for stepped stinger entry to no avail

apart from this reply you made ..

"and , not having a slow taper exiting from a stinger insert.
This should have a 45* step , and reduces the effect of the waves bouncing up and down the stinger , from the atmospheric end ( the muffler entry in the case of a KZ ).
These can interfere with the main positive reflection off the reverse cone , as the + wave bouncing off the open ended pipe reverses sign and travels back to the stinger entry."

but im struggling to visualise that.

[Peljhan]

Me and friends bought about 10 books combined. I am happy that it helped you as you helped us with 2t tips and tricks. Stay healthy!

[porttiming124]

Jan, are there any English version books left?

[koenich]

Jan, are there any English version books left?
jep, I just ordered one :niceone:

[wobbly]

Al , the sketch I did of the KZ stinger tells you everything.

[aljaxon]

Al , the sketch I did of the KZ stinger tells you everything.

i saw that a week ago but didnt realise that was the stinger diagram.

i cannot fathom it out sorry.

sorry to be a pain.

[wobbly]

What is there to figure out - the stinger is a tube approx 3mm bigger ID than a nozzle insert that is up against the rear cone exit.
There is a small taper on the insert entry to match the rear cone exit ID .
The original insert was a tophat to locate it in the end of the tube , and the stinger tube fits into a short female spigot welded to the end of the rear cone.
But the tophat , with the taper inside , in actual fact made the rear cone longer, so I cut it off.

In the KZ I cut the stinger short so that the insert would push in , up to where the bend started , so it would not go in any further.
And instead of a long slow divergent exit on the insert , I cut it to form a 45* step.
The step has virtually no effect on the outgoing wave , but reduces the amplitude of the return wave bouncing back off the stinger exit.

The small nozzle , large stinger idea was invented by Helmut Fath for Fast Freddies first NSR250GP Vee Twin , that had one stinger 150 long and one 450 long.
That small , short nozzle basically all but eliminated the tune difference between the two pipes on the Honda.

[Frits Overmars]

354262
Jan Thiel was urgently admitted to hospital two weeks ago. Three stents have been placed in his heart. He is now back home but it cost him a lot of money;
healthcare in Thailand cannot be compared to what we know here. That is why a campaign has been started to support him financially.

https://www.gofundme.com/f/can-you-help-to-generate-the-money-for-jans-inter?utm_campaign=p_cp+share-sheet&utm_content=facebook_cta_variant&utm_medium=social&utm_source=facebook

[porttiming124]

Thank you Frits for the information on Jan's state of health.
I just made a donation.

[aljaxon]

right i think ive got it. straight from the exit of rear cone i have a short inch length 1.5mm wall tube that is the same id as my tuned id and the same size as the rear cone exit. and the exit of that nozzle has a 45 degree chamfer. and then slotted over that is my "stinger.

im wondering can i fit my silencer straight over onto the nozzle? the silencer has a short inch length of plain tube and then a 170mm perforated tube with wadding around it and then back to a larger id plain tube exit.
maybe the perforations will help reduce the amplitude of any residual waves?

or do i need a length of plain tube stinger first?

ive noticed the smaller moped and scooter tuners seem to prefer side belly exit stingers or side bleeds as they call them. but not many race bikes seem to have them. is there a reason?


ive made a small donation because jan was kind enough to chat to me on facebook messenger for an hour or so a couple of years ago amongst other things trying to describe to me what a wave actually was so i could understand better exactly what was going on inside a pipe.

[wobbly]

Here is how I did it on the original test KZ pipe - easy to change nozzle ID.
Most tube is 1.5 wall thus with 28OD stinger it is 25 ID and the insert is 23mm.
But 1mm wall is available = 26 ID with a 23nozzle = 3mm step - this works better.
On other projects I have ended up with 5mm step and that is better again

[wobbly]

I have read Jans book - really, really interesting.
So my suggestion is we keep passing this around for what it cost - and send the money to Dolph via WISE - really easy and he benefits plus you get the book immediately.
Only $7.00 to send anywhere in a Post Office bubble bag in NZ.
Who wants mine - send DM with details.

[Grumph]

Here's one for Rob.
I had a look at the Stormer crank to do the balance factor. I want 60%.
It's had : a longer rod with a bigger pin - but hollow. Wheels machined for big end eye clearance and rod shank clearance - it's wider. Forged vs cast piston with a bigger gudgeon pin and needle rollers vs a bronze bush. So many changes.
Weighed it all up and reckoned I needed 152.8g of counterweighting for 60%.
Set it up and found that it was in equilibrium at 142g weight on the rod end.

So after all those changes it was only 10g away from where I wanted it.

[Storbeck]

Thank you Frits for the information on Jan's state of health.
I just made a donation.

I also made a small donation. I don't know Jan at all but he has added a bit of enjoyment to my life with the info he's shared on here and other places on the web.

I also have the book and it is great!

[aljaxon]

wobbly i see with that you can adjust nozzles as easily as replacing the silencer. i welded mine so its permanent. i suppose i can fit some thin walled tube inside mine with a slight top hat so it doesnt slot all the way through as long as my stinger can then slot over it.
ive found find with my small aircooled motors if i have anything like the small id outlet in the calcs i get too high temps when blasting it.


watch this video to to show how your recommendations of those percentages for header and diffuser to get more frontside power worked amazingly. showing new pipe on left and old high revving pipe on right.
both tests were using same rev range apart from at the end when the high revver carried on. obviously if i revved the high revver through the gears higher revs it could have matched the accell. but the intention was to design a road use/cruiser pipe.


https://www.youtube.com/watch?v=ACJ-VdgF1Fk

[Frank S.]

watch this video

Real world dyno 😅



btw: ordered the book and donated😎

[SwePatrick]

I tried to search.
But where do i order the book?

Rgds

[aljaxon]

Real world dyno ��



btw: ordered the book and donated��

once fitted an akrapovic full pipe pipe to my zx6r j1 and used a hd camera to film 3 runs with different jets. left fairings off so i could change them quickly. same road. then i transferred all the clips onto adobe premier pro and i cut the clips at exactly 6k rpm and then again at red line. and again at a few other chosen rpm ranges and it was then a simple case of seeing which was quickest ie the longest clips were slower. with the video software you could get accuracy to within a 25th of a second. and as you say real world.
plus i was doing it in every gear 2nd upwards at speeds up to 155mph. 5th gear. obviously it was a private test road.:innocent:

i got big differences and and did the same shimming the needles as well. it was a 2000 model and it got a reputation for being fast and most people, even pals slagged it off saying it had a zx9 motor in it. people heard about it and used to get in touch to race their 600's against it. lots of head shaking after i beat every one in a straight line. this was in 2010 so not bad for a ten year old bike.

ive just tested a pipe i made this week against those two using video clips and its even quicker!!!

the more accurate the tacho and speedo the more valid the results are.
im surprised a lot more tuners dont use video to gauge results instead of dyno's.
plus its a giggle.

[Frank S.]

I tried to search.
But where do i order the book?

Rgds

Just email to : LegacyJanThiel@gmail.com
They will send you the infos

[Gradella23]

felt like doing some manual work this morning, before and after rear cylinder skirt (was also plated in the meantime so the change in surfaces finish)

[SwePatrick]

Can we pull it off?
The chase for 80whp

Find out here:

https://www.youtube.com/watch?v=oKQkLp7HDBQ

[wobbly]

If you simply keep winding in advance and it keeps making more power every time , then it was way retarded to start with or the compression is too low - what is it ?
And something is seriously wrong if it looses power on Methanol " because its getting hot " when doing a back to back . That should never , ever be an issue on jungle juice.
You should be able to do 3 back to backs at a minimum with no power loss - again something is very wrong and it needs addressing.
One of the most important lessons I learnt from Jan was using EGT to get the tune dead the same every dyno run.
You need to find and settle on a specific egt the run ends on for every tune change - be it reed petals or ignition advance as the Exhaust temp in many cases has way more influence
than the change you did has.

[Vannik]

One of the most important lessons I learnt from Jan was using EGT to get the tune dead the same every dyno run.

You need to find and settle on a specific egt the run ends on for every tune change - be it reed petals or ignition advance as the Exhaust temp in many cases has way more influence than the change you did has.

This is what Jan said on the Dutch site, I translated it with his permission a long time ago:

354271

[F5 Dave]

Thanks will read that on different device.

Never got my egt reliable despite, ah never-ending.

People hate on dynojet but I often learnt things on all gears runs I missed. On singles.

[SwePatrick]

If you simply keep winding in advance and it keeps making more power every time , then it was way retarded to start with or the compression is too low - what is it ?
And something is seriously wrong if it looses power on Methanol " because its getting hot " when doing a back to back . That should never , ever be an issue on jungle juice.
You should be able to do 3 back to backs at a minimum with no power loss - again something is very wrong and it needs addressing.
One of the most important lessons I learnt from Jan was using EGT to get the tune dead the same every dyno run,
You need to find and settle on a specific egt the run ends on for every tune change - be it reed petals or ignition advance as the Exhaust temp in many cases has way more influence
than the change you did has.

:bs: :laugh: :laugh:

You´re welcome to come sort it out, pm for adress! =)
It would be quite cool the instead read some positive text from you.

Well think of this:
It must not be the 'powerproducing' things that are making it loose power when hot(cylinders, carburetors, pipe, reeds, etc etc)
There are more things, that huge tire for an example, a rubber belt that might slip ever so slightly, and so on....(this stresses out the transmission parts a LOT, it´s made for about 20-25hp)
I need to dyno it with somewhat 'cold' engine/pipes, as it is this way it is run on the track, you know, no heating and just full throttle when the lights go down.

It might get your thoughts on a different track.

[JanBros]

built a new dyno for my MX moped (50cc) using a complete drive-unit of a reach-truck
354276
so I needed new data and tested also all my exhausts again (runs are with the CVT blocked halfway, so it's only the engine).
one off them (the best one, RL the blue in the excel) I made some time ago with an excel from Coker Racing Products, but sadly I've lost that file so I do not know the specifics of it any more. So I've measured it up as good as I could and compared it to the best I've gotten using FOS (GY the green one), and allthough the power is quite similar, their shapes are very different :
354277354278
So my question : how come and what to change on them to get even better.

don't read too much in the HP-numbers, the dyno is "calibrated" using a good stock engine and adjusting the MOI so it put's out 2.5HP. after all it's all about comparing.

Data on the engine :
39x41.4
exh 188°
transfer 120°
sq 50% CR 12.8
354279

it is for Moped-MX, has CVT but I can not change the final gearring/ looking for power at higher rev's is useless, as there is usualy/sometimes only 1 long straight, but there are a whole lot of slow corners and we would lose a lot more comming out of slow corners than we would gain on the straight.

[wobbly]

SwePatrick - I wasnt being negative at all. Just trying to point out valuable lessons learnt the hard way.

But I fully stand by my comments about being able to suddenly wind in 3* of advance and a) be surprised it made more power and b) it didnt blow up.
To wind in that much advance it HAD to be retarded severely initially or the com is too low to begin with.
You didnt answer the question about what the static com actually is, and what is the peak power advance number now is just as important.

Methanol works best when at least 20% rich over stochiometric , and when its that rich you dont loose power nor get any power fade from it getting hot.
But what it does do is allow way more compression - safely with what would be regarded as a "normal " advance curve.
We have a member on here who wins 125 hydro races at 20:1 - alot higher than even the 18:1 that was used on 130 ELF in GP racing.
EDIT - this makes way more power than less compression and alot more advance.

So how do you know you have the best combination of advance/com/egt if you dont have the egt data.
The pipe must have been designed with a bulk gas temp in mind - so how do you know you are even close to that - apart from the fact it revs to some particular number.
But Methanol always revs harder than theory would predict - as it operates as though you were using a PWM powerjet solenoid because its not affected by the carb going rich over the pipe peak.

Imho you simply cant tune accurately and make informed decisions without sufficient data.
Ages ago I detailed what happened after Jan told me about having a target egt that you stick to that eliminates that effect from any change being made.
I tested a huge range of reeds and insert stuffers and one stood out as being the best by quite a margin.
But after going back and doing the test all over again , and changing jets each time to hit the same egt number , what was the worst reed/stuffer setup was now the best
as it needed alot less fuel to make alot more power ie a better bsfc ( Kg fuel/Hp/Hr ).
I hadnt even noticed that each time i made a change the egt was all over the place , and the good reed was down on power simply because the egt was 35*C lower.

Several others have made the comment about CVT being a nightmare to dyno accurately with , due to belt slip changing with heat, and some have resorted to locking out the CVT pulley.
And they were logging engine Vs drive rpm to generate a slip readout to tune the CVT.
But the fat tyre eliminates tyre slip on the roller so thats a positive effect.

[husaberg]

built a new dyno for my MX moped (50cc) using a complete drive-unit of a reach-truck
354276

https://ukindustriestraining.co.uk/wp-content/uploads/2017/10/Forklift-Truck-1024x898.jpg

[husaberg]

Kevin Cameron article about 2t scavenging and the Jante flow machine:

https://www.cycleworld.com/searching-for-sense-among-different-two-stroke-scavenging-schemes/

Edit: another one

https://www.cycleworld.com/colliding-streams-versus-flow-symmetry/

In that cameron article with what it said about Kawasaki i can't help be reminded of how Jack Williams of AMC development fame used a homemade flow bench and added ink out of a airbrush to test for the areas with low flow that was mention in another cameron article.

They had to make their own flow bench as if AMC never made it they were not allowed to buy one, Typical pommy upper management.

Google found this

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 came up when looking for it its from a camera built into a piston

https://www.youtube.com/watch?time_continue=44&v=mbm7LzIecb8&embeds_referring_euri=https%3A%2F%2Fwww.britbike.c om%2F&source_ve_path=Mjg2NjY&feature=emb_logo
https://www.youtube.com/watch?v=7Iq1B-2paCs&t=136s

[Larry Wiechman]

https://www.osti.gov/etdeweb/servlets/purl/317135

[SwePatrick]

SwePatrick - I wasnt being negative at all. Just trying to point out valuable lessons learnt the hard way.

But I fully stand by my comments about being able to suddenly wind in 3* of advance and a) be surprised it made more power and b) it didnt blow up.
To wind in that much advance it HAD to be retarded severely initially or the com is too low to begin with.
You didnt answer the question about what the static com actually is, and what is the peak power advance number now is just as important.

Methanol works best when at least 20% rich over stochiometric , and when its that rich you dont loose power nor get any power fade from it getting hot.
But what it does do is allow way more compression - safely with what would be regarded as a "normal " advance curve.
We have a member on here who wins 125 hydro races at 20:1 - alot higher than even the 18:1 that was used on 130 ELF in GP racing.
EDIT - this makes way more power than less compression and alot more advance.

So how do you know you have the best combination of advance/com/egt if you dont have the egt data.
The pipe must have been designed with a bulk gas temp in mind - so how do you know you are even close to that - apart from the fact it revs to some particular number.
But Methanol always revs harder than theory would predict - as it operates as though you were using a PWM powerjet solenoid because its not affected by the carb going rich over the pipe peak.

Imho you simply cant tune accurately and make informed decisions without sufficient data.
Ages ago I detailed what happened after Jan told me about having a target egt that you stick to that eliminates that effect from any change being made.
I tested a huge range of reeds and insert stuffers and one stood out as being the best by quite a margin.
But after going back and doing the test all over again , and changing jets each time to hit the same egt number , what was the worst reed/stuffer setup was now the best
as it needed alot less fuel to make alot more power ie a better bsfc ( Kg fuel/Hp/Hr ).
I hadnt even noticed that each time i made a change the egt was all over the place , and the good reed was down on power simply because the egt was 35*C lower.

Several others have made the comment about CVT being a nightmare to dyno accurately with , due to belt slip changing with heat, and some have resorted to locking out the CVT pulley.
And they were logging engine Vs drive rpm to generate a slip readout to tune the CVT.
But the fat tyre eliminates tyre slip on the roller so thats a positive effect.

I can´t remember i wrote somewhere or said in the clip that i was certain of anything....
And i recall that i didn´t want to push it on the dyno, i said something like 'we take it on the track'.
That should tell you that i know there is more lurking inside.
And still, i never said the 'engine' alone was hot, i said IT is hot!
That includes the whole bike.

And as i need to see if it have any response at all from almost dead cold i run it at about 25-30degree watertemp only when starting the pull.

Dragracing is a whole other way of tuning things, as it is the first ~100ft it needs to pull hard without hesitation when 'cold'
I run it somewhat low in compression yes(16-1), this to 'spill out' some energy through the exhaust, this to get some exhausttemp early in the run.
I am well aware that it would produce more power with say 18-1 och even 20-1 but this makes it harder to build heat and by that get the 'correct' engine powerband.
I use the fact that a 'cold' pipe pulls harder down low in the launch, making it easier to setup the cvt(it is tricky setting it up at high rpms).

We only run 201m(1/8), the run is over in ~6-6.5 seconds.
Tell me your builds produce good 60ft on the 1/8 with 25-30degree of watertemp and i will listen.
Dynonumbers are just numbers, but it should work on the track also.

And the dyno reports ~92hp to the crank, i would say that is darn good even thou it is not perfect tuned yet.
I´m guessing if putting in some more advance it will level out at somewhere in the area of 95-96hp to the crank.
95.5/198cc=0,48hp per cc

Aprilia RSA (roughly 59hp to the crank) on 124.7cc is 0,47hp per cc

Somewhere something is working quite good with these things that haven´t been professionally developed for years and years in an enginelab.
I do not need to know exactly all things with sensors and decimals, i read the plugs, as all dragracers do.

Tuning in dyno with cvt isn´t hard, you just set dyno up a little bit different(locks the gearratio), and setting up the cvt different from actual setup on the track.
Just put in some weight to get the cvt the change the gearratio early in powerband, by this you get the 'peak', setting cvt up for high rpm you might go past the peak and not getting the numbers at a lower rpm.

I run early in the pulls only ~250degree exhausttemp, it raises during the pull to about 400degree, pulls are taking ~4.5s.
Somewhere in the area of 430+-20degree seems to be the sweetspot
'cold' this engine peaks at ~13300rpm, and with some serious heat it peaks at ~13800-13900rpm.
But the torque cold down at 10500rpm is HUGE compared to 'hot'
Can´t remember the number on top of my head now thou.

[jonny quest]

You set up retarded ignition for when clutch is pulled in revving waiting for light.

This gets pipe hot for your run

[Frits Overmars]

I run it somewhat low in compression yes(16-1), this to 'spill out' some energy through the exhaust, this to get some exhausttemp early in the run.Makes sense.


I am well aware that it would produce more power with say 18-1 och even 20-1Not necessarily. It depends on how efficiently the pipe deals with the exhaust gas energy.


Tell me your builds produce good 60ft on the 1/8 with 25-30degree of watertemp and i will listen.I do not expect Wobbly to loose much sleep over whether you are listening. We offer what we have to offer and what you do with it is your choice.


95.5/198cc=0,48hp per cc. Aprilia RSA (roughly 59hp to the crank) on 124.7cc is 0,47hp per cc. Somewhere something is working quite good.The fuel maybe?

[wobbly]

Not interested in a flame war but I believe you are overlooking a couple of factors in the drag engine performance envelope.
Running Methanol it is technically normal to gain around 9% Hp simply due to the combustion energy increase of over 1/2 the A/F ratio.
With all out mods it is easily possible to double that increase - been there/done that.
So putting your 100cc cylinder back on petrol like the RSA that reduces the power to something like 0.39Hp/cc from the mechanical part development.

And why is it that in every form of drag racing the consensus is to be reving the engine right up to its mechanical limit ie 500cu in V8's going to 11000 + rpm
to take advantage of the gearing torque multiplication.
You are running the 100cc to 13000 , same as the 125 RSA peak Hp - seems to me you are leaving a shit ton on the table as using that 39Hp/100cc this would simply ratio up by 39*16000/13000 = 48Hp
if you maintain the torque at that rpm.
Plus add the fuels induced efficiency = 48*1.18 = 57Hp*2 = 114 crank Hp - and 16000 rpm is 25M/s piston speed on a 4.7cm stroke , very easily achievable and reliable even in kart scenarios - now you are getting
serious @ 0.57Hp/cc.
Then add in the gearing multiplication for way faster acceleration and or terminal speed, seems a no brainer - even if you halved the rpm increase to only 14500.

Edited to show the piston speed @ 4.7cm stroke - safe as hell.

[F5 Dave]

Those 100cc Roost barrels do look fantastic though. Far better than the 1978 rubbish we thought trying to triple port case reed was pushing the envelope. Pah . They would have been good to use, if maybe a planet away from the 'Spirit' of bucket racing.
But that was just rambling of a codger who didn't wish to push the written rule book.

[lodgernz]

Those 100cc Roost barrels do look fantastic though. Far better than the 1978 rubbish we thought trying to triple port case reed was pushing the envelope. Pah . They would have been good to use, if maybe a planet away from the 'Spirit' of bucket racing.
But that was just rambling of a codger who didn't wish to push the written rule book.

Says the codger whose 50 is still the fastest F5 bike in NZ.

[aljaxon]

in a nutshell
will a longer belly/shorter rear cone combo deter over rev more than a shorter belly longer cone?
same tuned lengths. same percentages.

ive realised i dont want to totally kill over rev in my ideal pipe for the puch road bike project.

[wobbly]

In a nutshell , a steeper rear cone has increased amplitude over a shorter duration = less front side and overev , more peak.
In fact a longer rear and shorter mid may be the go to in this case.

[Frits Overmars]

a steeper rear cone has increased amplitude over a shorter duration = less front side and overev , more peak.Yup, up to a point. If the rear cone is too steep, the return pulse can turn into a shockwave before it reaches the cylinder and then you will have less of everything.
Al, you next question will probably be 'how steep is too steep?'
I've tried to incorporate the optimum rear cone ratio in my FOS exhaust concept. You can go shallower if need be, but going steeper won't do much good.

[aljaxon]

ok thanks for the replies.
i built two pipes a fat and a thin one with same percentage header and diffuser 32 68 same tuned lengths.
thin one has 90mm long belly and stops revving dead at 8500 tuned length was supposed to be 8800
fat one has 73mm long belly and revs to 10000.

fat ones belly = 4.8 times the start diameter of just under 25mm. ive never seen one as fat as that. 118mm. the rear cones angles are very sharp, im surprised it works.

im making 3 more pipes . i will reduce the angles and hence belly width will come down.

i'd love to try another FOS pipe but ive welded up my 29mm long cylinder duct to narrow ever so slightly from my single ex port area equiv 25mm to 24.5mm exit in accordance with wobblys duct formula. and using the fos calcs X = 25.8 and D1 wants to be 26.6mm as opposed to my 24.8

so ive got my age old problem of cylinder port exit not adhering to the FOS formula.

heres the two pipes ive made and road tested. the fat one works well apart from at 6k its misfiring. the thin one works well for a cruising pipe which i wanted but has no over rev. which i thought i didnt want but now i realise i would like a little.
with the fat one i wanted to use angles seen on 125/250 bikes pipes but my small start diameter doesnt allow such large angles due to simple geometry unless my belly gets obscenely fat.
https://live.staticflickr.com/65535/53494299567_bd30f9aebd_c.jpg

[wobbly]

Al , you are making it all way to complicated for a shitbox road bike.
The skinny pipe has way too steep rear cone angles for a cruiser , and the FOS design is worse , but I guarantee that is overscavenging the hell out of the cylinder due
to the steep diffusers.
With the little info I have here is a super simple layout that will work , if the TL is correct from the other two designs.
The diffuser is simply divided into 2/3 - 1/3 lengths and the belly diameter a guess to get a shallow rear cone to fit easily.
I have no idea if the 15mm exit is correct for the projected bmep.

[aljaxon]

lol shitbox road bike, i think mickey mouse hurts the bikes feelings less.

neither of those pipes - fat and thin were FOS. i just stuck to those 32 68 percentages. but went sharper angles on the fatty.
what i couldnt understand is the fat ones much sharper angles allowed over rev but the thin ones stopped over rev dead.


the thin one is a successful frontside cruiser pipe. no good for over rev.
but the fat one isnt much down on frontside yet has a better peak and loads of over rev.
yet i thought both the excessive volume and sharp angles would work against it?


massive thanks for that pipe design wobbly, . ill make that pipe plus a slightly thinner version of the successful fat one and id love to make an FOS pipe but my hurdle is my duct diameter of 24.5mm which follows your converging wobbly duct dimensions and not the D1 of 26.6mm according to the FOS calcs

as a builder i'd be tempted to just either blend it in slowly over the headers full length or deviate where i thought it would harm it less. but i accept that neither of those would adhere to the FOS recommendations and might be a total waste of time.


once again thanks for the help and advice.

re over complicating i just wanted to throw the kitchen sink at it.
ive always made single stage header diffuser and rear cones with a parallel belly. 3 angles in all. and been scared of complicating the maths and extra welding. but now ive done it its nothing to be scared of.

fatty
https://live.staticflickr.com/65535/53498314298_d1b7239800_c.jpg

[flyonly]

I am using an 2 stroke engine that is motocross based. The ratios are not ideal for top and the ratios are not very close. Does anyone have any tricks or ideas on how to find different gears that will fit my shafts or some other cunning plan? Not sure if there is a website with shaft sizes and centres out there?


Sent from my iPhone using Tapatalk

[F5 Dave]

Al, all I see there is heaps of room for a radiator and an auxiliary turbo water pump. Some time with a hacksaw. . .

[wobbly]

Al , a fat pipe will have way less wave amplitude as it enters the rear cone section. Thus what would be considered a very sharp rear cone of say 24* on an 80 Dia
belly section , would hardly develop any reverse pulse energy on a 118 Dia.
Thus the thin pipe would have no overev , and the fat pipe would act like it had only a 20* rear cone ie better frontside and overev power, by default.

[Grumph]

I am using an 2 stroke engine that is motocross based. The ratios are not ideal for top and the ratios are not very close. Does anyone have any tricks or ideas on how to find different gears that will fit my shafts or some other cunning plan? Not sure if there is a website with shaft sizes and centres out there?


Sent from my iPhone using Tapatalk

Welcome to the group on here who are struggling with the same problems as you. Make, year and model will help with any advice.

[flyonly]

KTM 65sx 50cc


Sent from my iPhone using Tapatalk

[flyonly]

KTM 65sx 50cc


Sent from my iPhone using Tapatalk

1. 2.846
2. 2.125
3. 1.722
4. 1.429
5. 1.217
6. 1.083


Sent from my iPhone using Tapatalk

[diesel pig]

1. 2.846
2. 2.125
3. 1.722
4. 1.429
5. 1.217
6. 1.083


Sent from my iPhone using Tapatalk

Admittedly they are more road ratios than race ratios

[Grumph]

Admittedly they are more road ratios than race ratios

But still six where some of us less fortunate are looking at four....Luxury.
Husaberg's the small KTM research expert. Away from home atm at the Burt Munro.

[porttiming124]

Frits.
Would it be possible to display your latest version of FOS exaust concept ?

[lodgernz]

Frits.
Would it be possible to display your latest version of FOS exaust concept ?

Here: #39051

[Flettner]

https://youtu.be/6_DQPLihXfo?si=BBm8xviPKdXCrKuH

[Frits Overmars]

Frits.
Would it be possible to display your latest version of FOS exaust concept ?...........
354303

[porttiming124]

thank you Frits

[peewee]

hey guys i picked up a 68x64 banshee mono block. its unplated with lower roof heights than a cub so theres a bit more freedom of port shapes and such. ive got engmod for assistance but still its only my hobby. oof drag pipes is what ill install. do you have any cyl advise before i bugger it all to hell ? :2thumbsup

https://i.ibb.co/Dwn34sY/20240130-193646.jpg

https://i.ibb.co/Sfvbsgy/20240130-193729.jpg

[aljaxon]

Al , a fat pipe will have way less wave amplitude as it enters the rear cone section. Thus what would be considered a very sharp rear cone of say 24* on an 80 Dia
belly section , would hardly develop any reverse pulse energy on a 118 Dia.
Thus the thin pipe would have no overev , and the fat pipe would act like it had only a 20* rear cone ie better frontside and overev power, by default.

that makes so much sense.

now why didnt i think of that....

[aljaxon]

Al, all I see there is heaps of room for a radiator and an auxiliary turbo water pump. Some time with a hacksaw. . ...

tempting....
ive even got a stihlsaw

[wobbly]

There are a few issues with this setup. Its a CPI Cheetah Cub that has been machined incorrectly with low ports - thats good as they have dumb transfers that open all together
and the setup had no attention paid to what the Blowdown STA was , even though the original had the main port opening at a real high 82* ATDC.
The cylinder responds real well to normal stagger , as it has no PV, and the A transfer roof is too shallow to start with.
Pay attention to where BDC of the ports actually is when you mock it all up - if the ports are low , that probably means the all the port floors are well below BDC , not good.

But the real issue is the crank - what is it.
Luckily this is set up for the 120 rod and a TRX piston, but none of the cranks I have seen in +10 are balanced even close to correctly for the long rod and heavy piston.
The next issue is the the case has to be trenched big time for the rod swing and then they are not reliable at all unless the case is welded.
Another possibility is there are a couple of billet cases being made , but the Mattoon is pretty agricultural.
Best to use straight cut gears and the extra plate clutch from Hinson - get the spring loaded type as the rubber button version is said to handle 100Hp - but it cant unless you make your own urethane buttons.
Put roller mains on the outsides.
And depending upon your end use , the RZ gears go straight in , and Nova make a 1st/2nd/3rd close ratio set to go with the 4/5/6 that are spaced well.
The Banshee gear set splits are horrible.

[JanBros]

I'm going to try to add an EGT sensor to my dyno.
at what distance do you place the EGT sensor in the pipe Wobbly ?
and what temp are you shooting for ? and is that temp BMEP-dependent or universal ?
or do I have to figure out the ideal EGT myself ?
(it's for not high BMEP air-cooled 50cc).

sorry if this has been asked already, but I can't find anything using the search and the google-site-search function no longer works on this site.

[wobbly]

Make sure you have a fast / exposed tip probe that sits on the header centerline - 3X bore from piston ( square engine ). I use Stinger probes from EGT Industries , they are the only
probes with a guarantee - used literally hundreds of them. Only just recently had a failure and that was the internal wire connection failing after 5 years use.

The actual egt is totally dependent upon the compression and the ignition timing used to suit the fuel.
But as I have said 100 times as you jet down one size at a time you will see a pattern of egt increase / jet size - say 20*C per jet.
As soon as you go down one size and the egt hardly increases, if at all , then that is the deto limit.

You may not loose power at the deto limit , but it sure as hell isnt safe going there.
There is an RAD / jet chart on my Wobblypipes FB page showing 3 different egt for max power just short of deto for 3 different fuels - same ignition timing , same compression.

[peewee]

There are a few issues with this setup. Its a CPI Cheetah Cub that has been machined incorrectly with low ports - thats good as they have dumb transfers that open all together
and the setup had no attention paid to what the Blowdown STA was , even though the original had the main port opening at a real high 82* ATDC.
The cylinder responds real well to normal stagger , as it has no PV, and the A transfer roof is too shallow to start with.
Pay attention to where BDC of the ports actually is when you mock it all up - if the ports are low , that probably means the all the port floors are well below BDC , not good.

But the real issue is the crank - what is it.
Luckily this is set up for the 120 rod and a TRX piston, but none of the cranks I have seen in +10 are balanced even close to correctly for the long rod and heavy piston.
The next issue is the the case has to be trenched big time for the rod swing and then they are not reliable at all unless the case is welded.
Another possibility is there are a couple of billet cases being made , but the Mattoon is pretty agricultural.
Best to use straight cut gears and the extra plate clutch from Hinson - get the spring loaded type as the rubber button version is said to handle 100Hp - but it cant unless you make your own urethane buttons.
Put roller mains on the outsides.
And depending upon your end use , the RZ gears go straight in , and Nova make a 1st/2nd/3rd close ratio set to go with the 4/5/6 that are spaced well.
The Banshee gear set splits are horrible.

hey mate ill put up some drawings they gave me with the cyl. ive not yet had a chance to drop them on the bottom end but i hope the trans floors arent well below the piston top edge. that would be completely dumb.
the common piston looks to be a 68mm blaster style but i suppose the banshee style could be used with a 5mm cyl spacer.
crank i have is a +10 billet with 115 rods made in house by crank works and roller bearings across the board. the rods look miles stronger than common 115 rods. i thought of 125mm rods but that opens a can of worms like needing expensive after market cases. my factory cases are trenched for rod swing. its not super deep so i hope it will be fine structurally.
also got hinson straight cut gears with springed basket. gearbox is 2-5 overide with billet 2nd
when you say normal stagger do you meen A open first then B then C ?

https://i.ibb.co/X7288FC/20240131-180049.jpg

https://i.ibb.co/Gs0dGkD/20240131-180129.jpg

[wobbly]

Aha , so the Serval is a different animal , maybe those port timings are low with the BDC in the right place - I had not seen that actual setup sheet before.
The 68/64 normal Cub is set up with a 120 rod and a option TRX piston.
Shit thats a very short rod on a big stroke - even the original RD400 with the 62 stroke was limited by those short 115 rods.
But yes stagger with the A opening first , the next two the same lower height and the boost lower again - works very well.
Having the ports all low like that makes it easy to get all the STA numbers correct very easily as its not plated.
And my choice would be the Banshee piston with the 5mm spacer to get some case volume happening.
CrankWorks are just as bad as plenty of others at using all the same components for a huge bunch of different combo's of stroke/rod/piston - so check what the BF actually is.

[porttiming124]

...........
354303

Hello Frits.
What is the way to measure the length of the Exaust runner according to you?354307354308

[Frits Overmars]

Hello Frits.
What is the way to measure the length of the Exaust runner according to you?I do it like this, with the depth gauge of the caliper in the top corner of the exhaust port, against the piston.
354309










​

[porttiming124]

Thank you Frits

[TZ350]

.
354311 354310 354312 354313

Stroked crank, pin hole welded and re machined for 45mm stroke (thanks Flettner).

This is to go with a big bore kit to make an F4 95cc, Suzuki RG50 engine with a rotary valve conversion.

To get close to 50% ballance factor I needed to make the counter weight heavier.

Managed that by removing a small amount of material on the crank pin side.

It is always a worry drilling holes here as it may loosen the crank pin. Anyway I kept them as shallow as possible and crossed my fingers for luck.

[F5 Dave]

Um, so like a 52mm piston?:scratch:. That one in pic looks smaller. What kind of barrel? A mate got an RG80 out of Germany, but it looked horrible .
Awfully oversquare, but would be superlight engine.
Oh yeah sorry for delay shipping parts but hard to get near po ATM.

[diesel pig]

.
354311 354310 354312 354313

Stroked crank, pin hole welded and re machined for 45mm stroke (thanks Flettner).

This is to go with a big bore kit to make an F4 95cc, Suzuki RG50 engine with a rotary valve conversion.

To get close to 50% ballance factor I needed to make the counter weight heavier.

Managed that by removing a small amount of material on the crank pin side.

It is always a worry drilling holes here as it may loosen the crank pin. Anyway I kept them as shallow as possible and crossed my fingers for luck.

As long as you cross your fingers on both hands you should be Fine!

[aljaxon]

I do it like this, with the depth gauge of the caliper in the top corner of the exhaust port, against the piston.
354309










​


at first i looked at it and thought thats wrong cos i and my 2 tuning pals been measuring to the centre of the port at piston end and centre at flange end to "average" out the distance. and then when i thought why you'd gone to the top i realised thats when the waves start and by the middle, where im measuring those waves are inconsequential.
its only a couple of mm and in theory my pipes will be shorter and revving 50rpm or so higher.
but bottom line is i and my pals have been measuring wrong.
cheers frits.

[Frits Overmars]

.It is always a worry drilling holes here as it may loosen the crank pin.Your concern is justified if the amount of remaining material between the crankpin bore and the balancing bores is smaller than half the crank pin diameter.
The effect of those balancing bores is proportional to their distance from the crankshaft center. Drilling those holes a little further away from the crank pin, and much closer to the outer edge of the crankshaft would have had more effect, i.e. you would have been able to make do with smaller bores.
354317










​

[wobbly]

Re the duct length - this as you say only makes a small difference , but Neels in his guide for EngMod uses the duct centerline length ie mid port height to mid exit face.
I have always used the average of the roof length and the floor length - measured as Frits described , from the port edges to the exit center.
Saying that the top timing edge is where the wave starts is correct , but we also have a return wave that begins occurring when the piston is near BDC - and that length is shorter.
So both the BDC and EPO lengths have an effect on that wave timing as seen by the port face.

This varying length effect also applies to a reed blocks intake length in the sim.
The length from the blocks mounting face to the petal tip is effective when the reeds are closed , but when fully open the length from the mount face to the beginning
of the port in the block is effective. In testing a CR125 with a fully instrumented dyno using TFX data logging for a PhD project I found that the effective average intake tract length worked
in reality from the bellmouth with end correction , to a point on the reed block ports that was 2/3 of the distance from the mount face to the tips.
This replicated perfectly in the sim , the wave action within the intake as seen on the instrumented engine.

[porttiming124]

Re the duct length - this as you say only makes a small difference , but Neels in his guide for EngMod uses the duct centerline length ie mid port height to mid exit face.
I have always used the average of the roof length and the floor length - measured as Frits described , from the port edges to the exit center.
Saying that the top timing edge is where the wave starts is correct , but we also have a return wave that begins occurring when the piston is near BDC - and that length is shorter.
So both the BDC and EPO lengths have an effect on that wave timing as seen by the port face.

This varying length effect also applies to a reed blocks intake length in the sim.
The length from the blocks mounting face to the petal tip is effective when the reeds are closed , but when fully open the length from the mount face to the beginning
of the port in the block is effective. In testing a CR125 with a fully instrumented dyno using TFX data logging for a PhD project I found that the effective average intake tract length worked
in reality from the bellmouth with end correction , to a point on the reed block ports that was 2/3 of the distance from the mount face to the tips.
This replicated perfectly in the sim , the wave action within the intake as seen on the instrumented engine.

Woobly.
Can you explain the (End Carburetor Correction) ?
What exactly is it for?

[TZ350]

354318

Had a couple of interesting bikes on the dyno today.

[wobbly]

An intake wave travels up and down the tuned length , and when a positive wave reaches atmosphere it is not reflected back directly from the face of the bellmouth.
The actual reflection point is past the end - as air is " soft " .
For a bellmouth inlet on a carburetor the end correction is a parallel length added to the end diameter that is 0.25 X the bellmouth inlet diameter.
So for a 38 Dia carb the end correction added to the bellmouth is a parallel 9.5mm section.

I know that BSL bike quite well - did it hit 155 RWHp like it used to.

[peewee]

Aha , so the Serval is a different animal , maybe those port timings are low with the BDC in the right place - I had not seen that actual setup sheet before.
The 68/64 normal Cub is set up with a 120 rod and a option TRX piston.
Shit thats a very short rod on a big stroke - even the original RD400 with the 62 stroke was limited by those short 115 rods.
But yes stagger with the A opening first , the next two the same lower height and the boost lower again - works very well.
Having the ports all low like that makes it easy to get all the STA numbers correct very easily as its not plated.
And my choice would be the Banshee piston with the 5mm spacer to get some case volume happening.
CrankWorks are just as bad as plenty of others at using all the same components for a huge bunch of different combo's of stroke/rod/piston - so check what the BF actually is.

ive tried stagger of A first then B then C / D the same. i never heard of A first then B/C same then D. is it something new ? whats the principle behind it ? did you do 1* steps ?

[wobbly]

The CPI cylinders all use the same configuration with an A port , then the B & C are like a big B port with a divider in it. Then the 2 x D ports are basically a normal boost port
again with a divider.
So I opened A first , then treated the B & C as a normal B only and made them the same timing - then as usual the boost ports lowest.
And the stagger was 1.8* A to B/C then 1.6* B/C to D.
Later I did Cheetah's with a PV , they had reverse stagger with the A low and 1* rise to the B/C/D same as the RSA.
Having the PV allowed very large triangular Aux ports helped by the low A - the STA's then matched well due to the large area of the 6 high ports.

[Frits Overmars]

Woobly. Can you explain the (End Carburetor Correction) ? What exactly is it for?
For a bellmouth inlet on a carburetor the end correction is a parallel length added to the end diameter that is 0.25 X the bellmouth inlet diameter.
354319
This picture is from my 'FOS Software' and 'FOS tips & concepts'. You can find it at https://1drv.ms/u/s!Atyzb5b7jtWNmVcX3c8D4Xr5eKjL?e=nxuw41
Everything that I make available there or via open forums such as KiwiBiker and Pit-Lane, or even via Fakebook, may be freely used and distributed.
So Wob, you already did a fine job with words, and you are very welcome each time you feel like illustrating your words.

[wobbly]

Thanks so much for your input Frits - not bad for a " Dutch motor mechanic ". I wonder if the evil eye of the Dragonfly is upon us still.
I see he has his very own Forum , where as Jaguar he rules supreme over a bunch of fawning acolytes that never dare transgress by disagreeing with anything spewed forth by his Royal Highness.

[skako]

Hi,
Attached is a graph simulated in EngMod2. The graph from EngMod serves me as a reference value for comparison with the graphs I get from my simulator (which is based on the first book by Prof. Blair).
Vannik already warned me earlier that the absolute values I get from that simulator can deviate significantly from reality.
I still "play" with that simulator because I can change its code. With minor or major additions to the code I run it through the ideal situation.
I wanted to see what happens at ( 0.666 x RPM_ power_ max ) if I remove the negative influence of pressure from the exhaust pipe in the BDC position, when the cylinder is maximally open.
However, I can't test 2-nd situations with EngMod2 to get good and accurate values.
EngMod is not designed that way. With a few lines of the author's programming code, EngMod would surely do it. I need a benchmark, so I can accept or reject the guidance from my simulator.
Perhaps this does not belong directly to tuning, but it still has something to do with tuning.

354322354323354324

[porttiming124]

An intake wave travels up and down the tuned length , and when a positive wave reaches atmosphere it is not reflected back directly from the face of the bellmouth.
The actual reflection point is past the end - as air is " soft " .
For a bellmouth inlet on a carburetor the end correction is a parallel length added to the end diameter that is 0.25 X the bellmouth inlet diameter.
So for a 38 Dia carb the end correction added to the bellmouth is a parallel 9.5mm section.

I know that BSL bike quite well - did it hit 155 RWHp like it used to.

Thank you Woobly

[porttiming124]

354319
This picture is from my 'FOS Software' and 'FOS tips & concepts'. You can find it at https://1drv.ms/u/s!Atyzb5b7jtWNmVcX3c8D4Xr5eKjL?e=nxuw41
Everything that I make available there or via open forums such as KiwiBiker and Pit-Lane, or even via Fakebook, may be freely used and distributed.
So Wob, you already did a fine job with words, and you are very welcome each time you feel like illustrating your words.


Thank you Frits

[porttiming124]

I took the formulas from Frits' picture.
For a 44 mm carburetor that gives me an external diameter of 141 mm.
the center center of the 2 cylinder in-line engines that I work have 118mm so it overlaps.
What do you recommend to me?
I cheat the formulas to have an external diameter of 118 mm or I cut a part from each so that they don't touch each other.354327

[wobbly]

Many engines have the same issue - cut a small flat on each bell so they will sit on the smaller centers.
Does not seem to affect performance at all.

[porttiming124]

ok thank you

[diesel pig]

Many engines have the same issue - cut a small flat on each bell so they will sit on the smaller centers.
Does not seem to affect performance at all.

Interesting stuff, does it matter if the flats cut on the bell mouths touch each other?

[TZ350]

354328


I know that BSL bike quite well - did it hit 155 RWHp like it used to.

354329

They weren't much interested in measuring dyno runs.

"B" was running Ok but 25 had some sort of issue where it just would not rev.

They ran 25 on the dyno and swapped parts from "B" hoping to find what part is crook on 25. But no luck.

354330 354331

Playing on the dyno chasing gremlins was much safer than blatting up and down the road outside Buckley's.

[wobbly]

Nope - the other way that McLaren did on the big V8 cars was to stagger the inlet lengths so they overlap.
A 2T has way less tuning effect from the inlet so it could work well.

[TZ350]

.
354332354333354334354335354336

Some more photo's of these remarkable bikes.

Wob had a lot to do with the design and building of these bikes and could probably tell us more about their history.

[wobbly]

I could bore everyone for hours about the BSL tech details , but here is a few bits.
It was the first bike to have the chassis CNC machined in pieces then welded together - the actual layout geometry was done by Mike Sinclair , crew chief for Yamaha and Roberts.
Also the first to have laser sintered cylinders made directly off my CAD files.
Of course the case was billet in two pieces. It was a 120*Vee with the RH and middle cylinder firing together and No3 LH firing 120 later.

It has a balance shaft driven of a gear pair between 1 and 2 , that shaft also ran across outboard as the primary drive , so it ran " backwards ".
The balance was done as an Engineering degree dissertation by Simon Longdill who tried literally hundreds of angles and firing orders I could dream up . He went on to do a PhD as well .
It ran perfectly smooth , no vibration at all - a dream compared to the Roberts triple that shook so bad it hurt your hand just warming up.
I tried an extra gear to change the crank to normal rotation , but it was clumsy engineering and the riders said it was no better in LH/RH flip flops due to the cranks rotational precession.

On the single cylinder dyno test engine with a 1:3 primary speed drop only it made just on 60 Hp/ cylinder at 11800 , on a Dynojet it made 155RWHP jetted rich as hell.
The ignition was done by EFI in Italy and it had all 2D datalogging of everything including egt and deto level.
The ignition stator was tiny using NdFeB super magnets from a F&P Smartdrive washing machine motor.
We developed a version of ATAC that was snapped open/shut at a predetermined rpm , it gave 28% more power just under the pipe.

Gearbox was all TZ500 gears made by Nova and we used pistons from Omega initially but ended up as Vertex - bore and stroke 59.6mm.
There was a YZR500 oil pump in the sump with an oiler across the top of the output shaft gears.
We tried a AP carbon/carbon clutch that cost 8000GBP , and it was a bike length faster on every gearchange , but the guys simply could not get a decent start with it no matter what.
Biggest error was I tried to copy the Yamaha method of having the big end pin integral with one web to make it narrower - didnt work , so we bored them out and pressed/welded normal pins
into those webs - was then dead reliable - the two bikes did over 500 laps around Sepang in 48* heat and 98% humidity , and cut times that would have been 12th in qually the year before.

When the FIM realized we had a good chance of scoring points , and if we did so that would have given us a team " franchise " like F1 had gone , they pulled our " development squad "
license and gave it to Ducati who didnt have an actual bike ( then 4T ) for another two years.
We were all ready to go race at Philip Island when we got the news - heartbreaking , and really was a waste of Bills money and years of hard work by alot of people.

[JdG]

FIM: Filthy Inbreed Motherfuckers


Verzonden vanaf mijn iPhone met Tapatalk

[41juergen]

[QUOTE=wobbly;1131222665]
We developed a version of ATAC that was snapped open/shut at a predetermined rpm , it gave 28% more power just under the pipe.

Was that incl. a PV system or w/o?

[pete376403]

I could bore everyone for hours about the BSL tech details , but here is a few bits.

The ignition stator was tiny using NdFeB super magnets from a F&P Smartdrive washing machine motor..

If nothing else this proves it was built in NZ.
Would love to be bored for hours - this is a story that needs to be told. And the FIM need to be up against the wall.

[wobbly]

It had a vertical curved blade PV system operated on a rack and pinion , that worked very well.
That was fully down up to around 7000 then ramped to fully up at 9800.
The ATAC system used a 20mm short pipe on the header close to the duct exit , with a butterfly plate that blocked the tube to the Helmholtz bottle that was 1.5 X the cylinder displacement.
Any bigger made no difference - and the blocking plate had to be snapped shut at one rpm point - below that point it made really good extra power , but
if it was ramped slowly it simply lost power instantly.
With Philip Island gearing on it did a demo day at the old Pukekohe track with the Britten , and was running 305 Km/Hr down the shute @ 12400 , a record to this day I believe.
Of course with 500GP power to weight it smoked the Britten easily, except at the hairpin we didnt have a 1st short enough as that was way tighter than any corner in GP racing.
Every gear had 3 or 4 options.

[Grumph]

The pic with the bottom pipe shows the ATAC chamber well. But in the pic of the top pipes there's the PV mech but no ATAC.

Different bikes/different versions ?

[wobbly]

The last couple of set of pipes were done in Ti , welded by Steven Briggs in an Argon box like a bead blaster setup with sealed gloves and a glass front , as I was way too busy doing CAD, redesigning the
carb bowls etc. As the Keihins were essentially back to front , the float levers didnt work under brakes , so it flooded. I ended up making new bowls with Yamaha floats/needles on sliding pins up from the bottom.
Never had an issue again. Those bowls are in one of the pics above.
The pipes had a divided tube ATAC across the top just behind the PV - dont know what happened to those pipes as it seems neither bike has them on.

Here is the billet case - a million hours of CAD
Two days/two shifts of 6 axis CNC - there are no corner rads in the file as we used ball nose cutters and Gibbs didn't like seeing a corner rad the same as the cutters geometry.
You can see the cover in the pic for the extra drop gear we never used to reverse the crank rotation - that is the silly money carbon/carbon clutch we couldn't use as well.

[jonny quest]

Wobbly, did you use a bridged ex port?

[wobbly]

Yea a T port - based on the facts of Honda's 500's successes and then suddenly Yamaha had blitzed the 250GP with one in a square engine for the first time,
That was a mistake , in hindsight - it caused all manner of drama with piston shape even though I had the bridge relief correct , as a 3 port is capable
of more power.
I did try " fixing " the T port by having the outer edges the highest , to ameliorate the huge difference in duct lengths the T suffers from , that is helped in the 3 port
by having the Aux lower , but although this did work I believe I could have made more power using the simple 3 port concept.
Not that it needed more power at the time really, but there's no such thing as too much as long as its friendly , and we did have super big bang.

[diesel pig]

[QUOTE=wobbly;1131222705]I believe I could have made more power using the simple 3 port concept./QUOTE]

That's good to read. It confirms my thinking about my next project. And by the way did the ATAC have a simple flat plate valve when it was closed or was it shaped to match the shape of the header pipe?

[wobbly]

The ATAC tube had a simple flat butterfly as close to the header as I could get it. The plates were machined , a bunch together on an angled mandrel in the lathe , so
they sealed perfectly without jamming.
The pipe was checked on the single mule dyno and once the plate was closed it had no effect on power over a " normal " pipe - yea a real pleasant and rare surprise , I drank a couple of very expensive reds with Bill that night.
The next day I discovered a bunch of pipe power in the sim , so I had to do the red thing all over again - great idea that of killing the slowest brain cells.

[speedpro]

. . . and was running 305 Km/Hr down the shute @ 12400 , a record to this day I believe.

Maybe. I calculated 311k @ 9,000rpm with 15:27 gearing on my turbo. The cop with radar at the kink said 312k. Disappointing at the time but I doubt there was a way to get around the kink going any faster.

[wobbly]

Didn't know that , we could have gone way faster , but as it was 1st gear out of the hairpin was already a nightmare - pulling 12400 in 6th was overving to hell.

[F5 Dave]

Um, perhaps 2000 ish remember sitting at PI and Mark Willis was trying to qualify. I remember the name as he shared it with childhood next-door neighbour.

[lodgernz]

I did try " fixing " the T port by having the outer edges the highest , to ameliorate the huge difference in duct lengths the T suffers from , that is helped in the 3 port
by having the Aux lower , but although this did work I believe I could have made more power using the simple 3 port concept.


Wobbly, for those of us stuck with a T-port cylinder, do you think it worthwhile to try this idea of raising the outer edges?

[Grumph]

Wobbly, for those of us stuck with a T-port cylinder, do you think it worthwhile to try this idea of raising the outer edges?

And if it is, any suggestions for the duct shape ?

Thanks.

[F5 Dave]

And just for weirdoddity my somewhat fallible memory suggests (from peering in one 10 years back) the VJ23 RGV has both Bridged port and auxiliaries . It was also mounted on the cases on-the-piss by say 15 degrees perhaps to give the inlet and outlet an easier path as V angle was closed up to 70* from 90* of first 21s and 22s.


Oh the tangled Web we weave. . .

[wobbly]

Well the big issue is being able to keep the correct port timing , when modding an existing cylinder.
The two things to keep in mind is that having the hooks just outside the outer corners pointing at the bore center is a huge factor for the port Cd.
and of course all these years later you have my Wobbly Duct geometry , that works perfectly with a T port.
The exit should be oval , its width being the diameter of the header entry = 100% of the port effective area , and its height should give you the 75% area.
Honda A kits were very close , with 41 X 35 oval , no steps , into a transition out to 41 Dia.

EDIT - The VJ23 porting was horrible - worst of all scenarios duuno what the hell the just graduated sewing machine engineers were thinking.

[jfn2]

Wobbly
How much higher would the outer T-port heights have to be, on adverage, compared to the center height, 1 deg, 2degs or more?
As I think of this, I suppose it would be just as easy to run the simulations to find out. What do you think?

[wobbly]

On the 59.6 stroke I ended up with 1.6mm , no idea now what that was in timing.

EDIT I tried putting a -1.5 mm slant height into a T port and it doesnt seem to work.
Contact Neels to do an update to allow this geometry.

[wobbly]

Just for info I discovered Avejas is advertising his deto knock sensor box again on Ebay - havnt seen it for ages.
Ive used dozens of the things for over 10 years , they work perfectly.
You can order the 0-5V output for data logging - as well as add an ouput that shorts to ground when deto is happening.
This is great with an Ignitech input that retards a setable amount when its grounded.
The Bosch sensor with an 8mm hole can be got for nothing from wreakers or new on Ebay as well.


https://www.ebay.com/itm/185739104413?_trkparms=amclksrc%3DITM%26aid%3D7770 08%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D202308 11123856%26meid%3D558f87a0c35c42f0961346da51c4f78b %26pid%3D101770%26rk%3D1%26rkt%3D1%26itm%3D1857391 04413%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3D RecentlyViewedItemsV2%26brand%3DUnbranded&_trksid=p4375194.c101770.m146925&_trkparms=parentrq%3A8b31bad418d0ad91b3ddb9eeffffe 18e%7Cpageci%3A5a26e872-c6df-11ee-8297-9a46053fb8f4%7Ciid%3A1%7Cvlpname%3Avlp_homepage

[jfn2]

Wobbly
Thank you for the reply!

[SwePatrick]

I have installed launchcontrol on the piaggiotwin and was about to test some settings in the vario and ignitech: 'just a warmup pull first and then i´ll be good to go'


https://youtu.be/danCPUbjxDA?si=N1kAOPW7k1L-KLwe

A few days earlier, when i did a fast test of the function:


https://youtube.com/shorts/0qrw3mhTJ7s?si=h9JpsPrHkGH7My1o

In the later part of the carnagevideo i setup my tzr250 again that i have converted to injection.
I have changed some fuelstrategy and did a couple of runs, a little bit off in power, but i´ll find it again, no problemos, just some mapping to do.(i have dyned as best 80.3rwhp with injection, now it was 74.x)
This day i wanted to test some other things to learn more about the MAXXECU that i use.

Edit: i also have installed larger injectors for future test with methanol, so this throws away the fuelmap some also.

[aljaxon]

Just for info I discovered Avejas is advertising his deto knock sensor box again on Ebay - havnt seen it for ages.
Ive used dozens of the things for over 10 years , they work perfectly.
You can order the 0-5V output for data logging - as well as add an ouput that shorts to ground when deto is happening.
This is great with an Ignitech input that retards a setable amount when its grounded.
The Bosch sensor with an 8mm hole can be got for nothing from wreakers or new on Ebay as well.


https://www.ebay.com/itm/185739104413?_trkparms=amclksrc%3DITM%26aid%3D7770 08%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D202308 11123856%26meid%3D558f87a0c35c42f0961346da51c4f78b %26pid%3D101770%26rk%3D1%26rkt%3D1%26itm%3D1857391 04413%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3D RecentlyViewedItemsV2%26brand%3DUnbranded&_trksid=p4375194.c101770.m146925&_trkparms=parentrq%3A8b31bad418d0ad91b3ddb9eeffffe 18e%7Cpageci%3A5a26e872-c6df-11ee-8297-9a46053fb8f4%7Ciid%3A1%7Cvlpname%3Avlp_homepage


would this work with say an rd350A with powerdynamo (vape) ignition? or even a single cylinder moped? im not that bothered if it doesnt do the retard under grounding with every ignition stystem. as long as i get a good early knock detection in order to have enough time to shut off. where does the sensor get mounted? cyl cyl head or crankcase?

i fitted egt gauges on my rd350A thinking it would be an early warning system. all they did was tell me what temp my engine melted at.

for £100 gbp (with sensor) this seems well worth it if it would indeed give me enough time to avoid holed pistons or damage.

[wobbly]

Well if you melted an engine when using egt , all that says is you were not using them correctly at all.
But the answer about the deto system is that it is adjustable to a preset amount of sensitivity , that will light up several led's to show deto onset , that then has a huge red light the instant
real deto starts.
So plenty of time to back out of it , before damage.
But in the case where you get deto onset , the egt has already flatlined or started to suddenly drop , so why do you need another gauge to ignore.

[husaberg]

Well if you melted an engine when using egt , all that says is were not using them correctly at all.

But in the case where you get deto onset , the egt has already flatlined or started to suddenly drop , so why do you need another gauge to ignore.
What would be the appropriate corect temps for AC and LC engines.

[wobbly]

How long is a piece of string.
You have Yamaha KT100 on 91 petrol that run at 650*C all day.
Then you have a Banshee that will melt @ 600*C on 110 race gas.
No such thing as any guideline as to what an engine will make max power at , nor what egt it will detonate at.

But a real simple guide is that when starting rich , the egt will rise at a near constant rate per jet size , say 20*C per jet.
As you lean down , suddenly the egt may only rise 5* or not at all , that is onset deto , so back out real quick and go back to safety.
On the dyno its very easy to watch the egt during the run , and you quickly recognize the telltale sign of the egt rise , slowing down , and power will stop rising as well.

All this assumes you are using exposed tip egt probes that are on the header centerline - running enclosed short things only 10mm into the header is a complete waste of time.

[F5 Dave]

Works great bolted to watercooled stuff. Air-cooled may be harder to achieve. And its already 'ringing'. That may cause issues.

[aljaxon]

to be fair these were too cheap to expect to be accurate, the needles were all over the place. i did insert the probes into the centre of the header and 150mm from cylinder exit. but i soon stopped watching them as they were a waste of time. i was told to watch out for a drop in temp as the early warning. but every time i opened the throttle the temp dropped. fresh charge in the pipes?
only left them fitted on the bike for show raised eyebrows at cafes etc.

i do have decent spark plug washer sensor fed temp gauges and they let me know when im getting hottish and i keep my eye on those. have them fitted to a few of my 2 strokes.

but i would love a deto sensor. only thing is i reckon i would need to initiate deto first, eg advancing the ignition etc to calibrate them? so as to have a reference point?

and F5 Dave i didnt quite understand the already ringing = Air-cooled may be harder to achieve. And its already 'ringing'. That may cause issues.
you mean the noise on a worn aircooled motor? i rebore once ive got piston slap so might not be an issue for me.

[F5 Dave]

The fins themselves vibrate. It is measuring a piezo sensor for knock shock. Can it ignore the fin vibration? Especially as - where do you mount it?

[wobbly]

Gauges with needles are useless on a 2T , they sample so slowly and react even slower that as you say the thing has seized before the sensor had realized what's happening and told the world.
Aircooled is irrelevant , the background " noise " of an engine is nothing even remotely like the frequency and amplitude signal of deto events.
You initially calibrate the gauge ( with the sensor under a head stud , or I have even clamped one to the frame fitting boss on the back of a CR125 head ) and rev/blip the shit out of the thing.
When set overly sensitive the background mechanical clatter will light up a couple of the lower 5 indicator lights , turn it down a bit and its done.
You know its set right when under full throttle load against the brakes or up a hill , the lowest indicators flicker.
Then the instant deto starts a couple more lights come up , then actual deto "shock " causes the big red warning LED to flash - REAL bright.

Here is a Bosch sensor fitted to a TM on my dyno

[Rudex]

Hi Wobbly,

Can you share tips to measure correctly one pipe built?. Normally I measure the short and lenght inside and outside of each pie cuts. But later the angles doesnt fit perfectly and it is difficult to draw in cad.

For example, in kart pipes, in FIA papers you can check the measures but How do you draw in cad the values to fit correclty?.

Regards. 354352

[wobbly]

Thats easy to draw out from the CIK papers. Each line with inside and outside dimensions , plus the cut length , represents a straight cone that has been cut at an angle.
Thus if you draw that angled cut in CAD and extend the shorter length past that cut , then draw a new line thru the mid point of the cut perpendicular
to the cone centerline , that will give you the straight cone dimensions and the cone angle.
The only thing to be aware of is that often the first few cuts are not shown as inside and outside dimensions correctly , as the pipe is bent upwards , not around the corner.
Also all CIK dimensions are outside.
EDIT - sorry I forgot to add the straight line length to the sketch .

[Pagi]

Just for info I discovered Avejas is advertising his deto knock sensor box again on Ebay - havnt seen it for ages.
Ive used dozens of the things for over 10 years , they work perfectly.
You can order the 0-5V output for data logging - as well as add an ouput that shorts to ground when deto is happening.
This is great with an Ignitech input that retards a setable amount when its grounded.
The Bosch sensor with an 8mm hole can be got for nothing from wreakers or new on Ebay as well.


https://www.ebay.com/itm/185739104413?_trkparms=amclksrc%3DITM%26aid%3D7770 08%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D202308 11123856%26meid%3D558f87a0c35c42f0961346da51c4f78b %26pid%3D101770%26rk%3D1%26rkt%3D1%26itm%3D1857391 04413%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3D RecentlyViewedItemsV2%26brand%3DUnbranded&_trksid=p4375194.c101770.m146925&_trkparms=parentrq%3A8b31bad418d0ad91b3ddb9eeffffe 18e%7Cpageci%3A5a26e872-c6df-11ee-8297-9a46053fb8f4%7Ciid%3A1%7Cvlpname%3Avlp_homepage

Wobbly,

do you mean this BOSCH sensor : https://www.ebay.com/itm/314953619527?_trkparms=amclksrc%3DITM%26aid%3D1110 018%26algo%3DHOMESPLICE.COMPLISTINGS%26ao%3D1%26as c%3D20210609144404%26meid%3D2402fcda75ca4972a3512f 6cf41d5bbb%26pid%3D101196%26rk%3D1%26rkt%3D12%26sd %3D185739104413%26itm%3D314953619527%26pmt%3D1%26n oa%3D0%26pg%3D4429486%26algv%3DCompVIDesktopATF2V4 WithDefaultIMAFeature%26brand%3DBosch&_trksid=p4429486.c101196.m2219&amdata=cksum%3A3149536195272402fcda75ca4972a3512f6 cf41d5bbb%7Cenc%3AAQAIAAABALHyIAEaemKG0mx4REjf%252 BHyi2kzcINSWjmv491TDyjbVmYwevKj0ejii%252FeyFe06fKn KtwDz4J2AYUJJ90MtbQaThoAmj5uzMsaq6y23wN46FuOM6WZgZ z6kjWAvxwRzF8qZQ6eQjq8KlehMg1bDhbANqDkbPmwlrjLfArR YAtmDWjKH0FIRGMY6FzfJ9Bg7OPTTrPuCJ5%252Fr%252BH2aE 53Wcq61CaB%252BOhfAhIc1JvT%252FAO3h5ZMkv4FEX2n5xU3 pmJ4EhyK7D%252B77mnBh26amahTUi384HkT%252Fv32epYYNN o5FLYxbx7icKaerS1I6eFgmBJZAjpoQQ%252BxkrBBtYBXuA4U m0iR4%253D%7Campid%3APL_CLK%7Cclp%3A4429486&epid=202841941&itmmeta=01HPH4SHANRGDC9ZG9NE21KJER

[Rudex]

Thats easy to draw out from the CIK papers. Each line with inside and outside dimensions , plus the cut length , represents a straight cone that has been cut at an angle.
Thus if you draw that angled cut in CAD and extend the shorter length past that cut , then draw a new line thru the mid point of the cut perpendicular
to the cone centerline , that will give you the straight cone dimensions and the cone angle.
The only thing to be aware of is that often the first few cuts are not shown as inside and outside dimensions correctly , as the pipe is bent upwards , not around the corner.
Also all CIK dimensions are outside.
EDIT - sorry I forgot to add the straight line length to the sketch .

Thanks Wobbly!.

If i understood well, You first draw the vertical line = 47.48mm , perpendicular line to this line (axis), the 65mm and 57.47mm inside and outside dimensions and the outside diameter. Maintain the program without restriction only symmetry between each side dimensions to maintain the same angle of both, and then you get the angle of cone. If I would want the straight cone get perpendicular line from center point. Like i did in example. The pie cue is 6.7º cut and 14.8º of input output angle.

This is easy in program like Fusion 360 or solidwork, in Autocad is a bit difficult.

If the pie cut is angled in the input and output I suppose it would be similar. Am I right?.

Yes, I know CIK diameters are outside, I get only the data like example. With a real pipe with several pie cuts (in header harder) is no easy to get the real dimensions. that's why I ask for tips.

354354

[ken seeber]

None of this big 50 cc or huge 125 cc stuff, just 35 cc, in this case for RC gas racing.
Not my project at all, but got the ok to post a couple of pics. Cast using 3D printed sand moulds.
Features pretty much "state of the art" transfers and exhaust ports and passages. It did get help from you know who, but no C port as it is piston ported.
This engine features a detonation free piston material.

354355354356

[lohring]

I love it. Where can I get one? By the way, I drew a piston ported engine with a C port. Is t better? I have no idea.

Lohring Miller

354359

[Frits Overmars]

I drew a piston ported engine with a C port. Is t better? I have no idea.

354359It looks nice. But won't it require rather long piston skirt sides that may get in the way of the transfer duct entries?

[lohring]

The skirt gets cut away except in the intake area. The bottom of the intake port is above the transfer entry. See the cylinder below that has a lot milder port setup. I'll do a drawing to check.

Lohring Miller

354361

[aljaxon]

re pipe making i have no where near the experience of some on here but i find i use cad only to draw a straight pipe with all its dimensions and maybe the centreline of a bending header with angles.
once ive got the angle of change of each section i then use a fantastic free program called cone v1.3
later versions v2.0 have a time limit and are not free.
you can input start and end angles and diameters and lengths for your cones and even adjust where the seam is using a box labelled Phi.

you do have to add on the thickness of your material to the diameters.

it outputs to its own .con files and also exports the flat pattern projection as a .dxf file which autocad reads and my local laser cutters have no problems with.

i sound like a salesman.

i know programs like torqsoft output all the dxf files for you (dunno about other progs like mota or engmod?) but ive got used to this and can output say 15 dxf files for a pipe in half an hour.

[aljaxon]

Al , you are making it all way to complicated for a shitbox road bike.
The skinny pipe has way too steep rear cone angles for a cruiser , and the FOS design is worse , but I guarantee that is overscavenging the hell out of the cylinder due
to the steep diffusers.
With the little info I have here is a super simple layout that will work , if the TL is correct from the other two designs.
The diffuser is simply divided into 2/3 - 1/3 lengths and the belly diameter a guess to get a shallow rear cone to fit easily.
I have no idea if the 15mm exit is correct for the projected bmep.

i built this pipe thanks Wobbly and just road tested it now (yet to try different jetting but seems ok) and using video speedo comparison it has the same accel as the thin pipe, but is ever so slightly slower acell than the fat pipe in the top 2 gears. fat pipe with its over rev to 10k can change up back into the power.

the fat pipe is still the best pipe yet shouldnt work and the rear cones are probably only for ornament?

all have same tuned length, thin stops revving at 8k, your pipe stops at 9k and the fat revs to 10k. all have exactly the same wobbly duct geometry built into the header.

i am stuggling to notice patterns of different pipe geometry in relation to on-road performance.

i am about to build 2 more pipes, one of them is an 80% thinner version of the fat pipe and the other i did take the liberty of tweaking your design by adding a 2 stage header and a 3 part rear cone which starts off shallow then steepens with each cone much like the fat pipe and maybe this initial first shallow rear cone is helping the over rev?

over rev was something i initially didnt want but have since realised with spaced out gears and only 4 of them it is essential.


for cruising purposes only all 3 pipes are a success.

[katinas]

I love it. Where can I get one? By the way, I drew a piston ported engine with a C port. Is t better? I have no idea.

Lohring Miller

354359

With this nice scheme, maybe intake window can be opened in progressive way. Longest duration at the farthest wall of intake channel and shortest duration near C.
With more extended intake channel under A, although this will not increase the cross-section of the channel, maybe even longer duration possible without revers flow.

[philou]

"The diffuser is simply divided into 2/3 - 1/3 lengths"


This is the rule that "Jean Louis Millet" tells us.
the French exhaust specialist

[SwePatrick]

A little movie to get you going this late friday afternoon.
(i promise, it revs like a mother when i put some load to it)


https://www.youtube.com/watch?v=56nynYbnbOY

[aljaxon]

so now the goalposts have moved in the quest for a perfect cruising pipe cos now it needs a bit of overrev to get me back in the power on changing up.

im guessing if i made your (wobbly) pipe design diffuser just one angle that would give me more overrev? cos it would be a steeper angle nearer to the header returning the wave quicker hence better at higher rpm

[aljaxon]

"The diffuser is simply divided into 2/3 - 1/3 lengths"


This is the rule that "Jean Louis Millet" tells us.
the French exhaust specialist


is there anywhere i can see some more of his "rules"?


the pipe that wobbly designed for my purposes demonstrates this percentage within 1 %

as i now understand the sharpest change of angle in the diffuser is where the amplitude will be highest. so not only is it about percentages but what angles they are and where in the diffusers length they occur.
nearer to header = higher up the rev range and vice versa.




has anyone ever designed a pipe that has an initial sharp diffuser followed by a very small angle mid maybe even straight? followed by a final sharp angled last difuser section? to try and enhance power at the extremes of the rev range ? in the process not sapping as much energy so there is loads left for the rear cone? as in the pic below.

the lengths and diameters are wrong but the angles are total and correct
https://live.staticflickr.com/65535/53534426818_7842a43cc9_c.jpg

[katinas]

is there anywhere i can see some more of his "rules"?







has anyone ever designed a pipe that has an initial sharp diffuser followed by a very small angle mid maybe even straight? followed by a final sharp angled last difuser section? to try and enhance power at the extremes of the rev range ? in the process not sapping as much energy so there is loads left for the rear cone? as in the pic below.

the lengths and diameters are wrong but the angles are total and correct
https://live.staticflickr.com/65535/53534426818_7842a43cc9_c.jpg

I'm not sure, maybe it's just a visual trick, but the first ring of the diffuser on YZR 500 2001 looks sharper for eye than usual.

[skako]

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

has anyone ever designed a pipe that has an initial sharp diffuser followed by a very small angle mid maybe even straight? followed by a final sharp angled last difuser section? to try and enhance power at the extremes of the rev range ? in the process not sapping as much energy so there is loads left for the rear cone? as in the pic below.

the lengths and diameters are wrong but the angles are total and correct
https://live.staticflickr.com/65535/53534426818_7842a43cc9_c.jpg

Hi Aljaxon,
I follow your tests and drawings. According to the description you gave, I adjusted your pipe drawing to LT= 820mm and Dmax = 83mm, for my 50ccm moped with piston-ported intake.
I compared the simulation and got a red characteristic graph.
My model is based on the FOS - pipe concept, which I slightly modified and after many attempts got a wider black graph.
I think that the FOS - concept is better suited for the 50cc class.

354381

[aljaxon]

good to see that skako. i am using the wobbly duct on all the latest designs ive done and was told that the FOS pipe doesnt work well with that.

ive got 2 more to build - 1 thats a mod of a pipe that wobbly quickly and kindly designed that im currently testing
and another thinner version of a fat pipe with belly size 4.8 x ex port area. which shouldnt really work well but its the best pipe ive made out of 5 in the last few months.
once these are done and tested i might try something similar to that last design with the 3 degree main diffuser cos its easy for me to cut out the existing diffuser on an old pipe and replace it with another diffuser.
im stuck with the start and end angle but can mess about.

im only testing the pipes by changing jetting and leaving ignition alone.
i do fear that by keeping the ignition the same im not realising the full potential of some pipe designs.

i have video clips for each pipe and can compare them to see real world road performance which i now believe to have more value for my (mickey mouse) purposes than a dyno graph.

im gonna have a search on here and see what youve been up to skako to see what i can learn

[philou]

is there anywhere i can see some more of his "rules"?




he is dead.
it was paid internships with him mainly focused on construction

generally, the leak tube for 50cc is 16 mm

[skako]

Hi,
I tried to adapt the wobbly pipe, #39123, designed for aljaxon to LT= 825mm for my model.
I adjusted the pipe to have the same inlet for a better comparison.
I tried to keep the angles and dimension ratios as much as possible.
I was interested in how close I am to the characteristics of the wobbly pipe, which can be seen on the graph.
I assume that aljaxon could expect a similar characteristic on his moped at lower RPM.

354396

[philou]

skako, you can test this one ?

Édit : 13 mm leak tube for 50cc o_0 it will break. the oil film in the cylinder will burn on the exhaust side

[Frits Overmars]

Hi,
I tried to adapt the wobbly pipe, #39123, designed for aljaxon to LT= 825mm for my model.
I adjusted the pipe to have the same inlet for a better comparison.
I tried to keep the angles and dimension ratios as much as possible.
I was interested in how close I am to the characteristics of the wobbly pipe, which can be seen on the graph.
I assume that aljaxon could expect a similar characteristic on his moped at lower RPM.
354396Skako, the 13 mm Ø restrictor in your pipe drawing corresponds neatly to the 13 crankshaft-kW (17,43 crankshaft-HP) in your power curve.
But as soon as the engine starts making more power than that, 13 mm Ø will be dangerously small.
As a rule of thumb the restrictor diameter should be at least 3,1* the square root of the crankshaft-HP. Also notice the comment in the FOS exhaust concept below.354398

[aljaxon]

he is dead.
it was paid internships with him mainly focused on construction

generally, the leak tube for 50cc is 16 mm

shame.
i use a 16mm stinger outlet on my aircooled 74cc kit and my ex port area is 25mm diameter equivalent and i find i do get quite hot under sustained high load.
i might try 17mm to see if temps come down.

[aljaxon]

Hi,
I tried to adapt the wobbly pipe, #39123, designed for aljaxon to LT= 825mm for my model.
I adjusted the pipe to have the same inlet for a better comparison.
I tried to keep the angles and dimension ratios as much as possible.
I was interested in how close I am to the characteristics of the wobbly pipe, which can be seen on the graph.
I assume that aljaxon could expect a similar characteristic on his moped at lower RPM.

354396

out of the 5 pipes ive made since october for this bike the lower "fat" one is the best pipe. stupidly fat 4.7 x belly to ex port area. using the wobbly duct geometry to start things off. ive left the dims off the lower pipes first part but they are the same as the above pipe. the too sharp rear cone doesnt mess things up because i am told the energy has all been used up by the diffusers sharp angles. its annoying because when i stick to the "rules" i get a lesser pipe.


https://live.staticflickr.com/65535/53494299567_bd30f9aebd_c.jpg

[Gradella23]

wob, i have a question regarding the tm head insert with squish band cooling that you posted some time ago.
You said that this gave a slight improvement, bringing the water near the squish but keeping the chamber hot.

but isn't the water substantially stagnant inside the holes? also in a rapid cfd simulation this is what looks more likely.
Wasn't it better with a continous 3-4mm groove around the same zone? maybe that might have caused some structural issues?

thanks!

[skako]

skako, you can test this one ?
.................................................. ...............................


I need more info in my inbox.

[wobbly]

The water is forced to flow around the annular ring above the drilled cooling holes.
Heated water in the holes naturally migrates toward the cooler water above and is being continuously recycled.
The annular ring is a compromise between beam strength and water flow capability.
This setup gave substantially less background deto level on the dyno , and on track allowed probably 2 jets or 30*C extra egt without deto.

[TZ350]

Just for info I discovered Avejas is advertising his deto knock sensor box again on Ebay - havnt seen it for ages.
Ive used dozens of the things for over 10 years , they work perfectly.
You can order the 0-5V output for data logging - as well as add an ouput that shorts to ground when deto is happening.
This is great with an Ignitech input that retards a setable amount when its grounded.
The Bosch sensor with an 8mm hole can be got for nothing from wreakers or new on Ebay as well.


https://www.ebay.com/itm/185739104413?_trkparms=amclksrc%3DITM%26aid%3D7770 08%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D202308 11123856%26meid%3D558f87a0c35c42f0961346da51c4f78b %26pid%3D101770%26rk%3D1%26rkt%3D1%26itm%3D1857391 04413%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3D RecentlyViewedItemsV2%26brand%3DUnbranded&_trksid=p4375194.c101770.m146925&_trkparms=parentrq%3A8b31bad418d0ad91b3ddb9eeffffe 18e%7Cpageci%3A5a26e872-c6df-11ee-8297-9a46053fb8f4%7Ciid%3A1%7Cvlpname%3Avlp_homepage


would this work with say an rd350A with powerdynamo (vape) ignition? or even a single cylinder moped? im not that bothered if it doesnt do the retard under grounding with every ignition stystem. as long as i get a good early knock detection in order to have enough time to shut off. where does the sensor get mounted? cyl cyl head or crankcase?

354402354403

[F5 Dave]

As you were. I'd thought there was problems with Air-cooled. I'd modded to water cooled for everything by then.
Still have to make special head bolts and be careful with torque evenly.

Sorry if I put you crook.

[Gradella23]

The water is forced to flow around the annular ring above the drilled cooling holes.
Heated water in the holes naturally migrates toward the cooler water above and is being continuously recycled.
The annular ring is a compromise between beam strength and water flow capability.
This setup gave substantially less background deto level on the dyno , and on track allowed probably 2 jets or 30*C extra egt without deto.

thanks, on cfd it's not easy to weight the natural convection from the holes to the upper cool flow, but you absolutely have a point here.

Have you tried the deeper annular ring solution? maybe half the depth of the holes for example.
Is it really critical from a strenght perspective? worth trying?

[katinas]

Tested this similar squish cooling type, but without holes. Flow rise up from the cylinder and then arranged down to squish area by cover deflector and then rise to outlet near spark plug.
Both piece made from 7075, but still not cracking.

[philou]

a test of Mota simulator automatic exhaust optimization feature.

this could be an additional function to bring to engmod



https://youtu.be/qyazo-LOung?si=xG87c5-pbJqArY1w


https://youtu.be/DPk1YjoOlqk?si=nRshN6E4ZBrQVM3q

[rgvbaz]

a test of Mota simulator automatic exhaust optimization feature.

this could be an additional function to bring to engmod



https://youtu.be/qyazo-LOung?si=xG87c5-pbJqArY1w


https://youtu.be/DPk1YjoOlqk?si=nRshN6E4ZBrQVM3q

Hi,

Just to note: the pipe in the latest video at Mick's isn't the same as the one in the video about the Mota optimiser. I'd like to build that one at some point to see how the inverse baffle will work in reality.

Cheers

Dave

[wobbly]

Inverse angle rear cones have never worked , unless its some very very weird application or particular effect being sought.
A generality I know but I tried several variations in Dynamation before Neels came along.
This geometry makes a high amplitude return wave very early in the plugging process with the piston closer to BDC where it should be still evacuating.

[skako]

skako, you can test this one ?

Édit : 13 mm leak tube for 50cc o_0 it will break. the oil film in the cylinder will burn on the exhaust side

Hi,
Here I tried to adapt Philou suggestion.
The simulation and the drawing for comparison are on the graph.
354408

I also tried to adjust the A.I. pipe design for my 50cc model. Simulations for comparison are on the graph.
354409354410354411

I still think that the FOS pipe can be adjusted well for engine.

[F5 Dave]

Hi,

Just to note: the pipe in the latest video at Mick's isn't the same as the one in the video about the Mota optimiser. I'd like to build that one at some point to see how the inverse baffle will work in reality.

Cheers

Dave
So why still the low revs?

Old road 125s did 25hp and managed 100mph. To do it with only 20 you'll need a great fairing and tiny rider I'd expect with spot on gearing and some luck.

Or, just attn to the crank bearing /rod choice and rings that cope with the revs without fluttering, push revs up 2000 rpm and 25hp will be easy. You're not building a high mileage bike are you?

[rgvbaz]

So why still the low revs?

Old road 125s did 25hp and managed 100mph. To do it with only 20 you'll need a great fairing and tiny rider I'd expect with spot on gearing and some luck.

Or, just attn to the crank bearing /rod choice and rings that cope with the revs without fluttering, push revs up 2000 rpm and 25hp will be easy. You're not building a high mileage bike are you?

Hi Dave,

Yeah, I'm certainly not there yet. Going by the previous attempt in Practical Sports Bikes I need at least another 3-4 hp. They had real issues pulling top gear so I'm contious of moving peak too high and reducing the power range.

I'll have a look at the STA available at a higher rpm.

I'm currently on a dykes ring piston. I'd like to swap to something single ring but the 12mm piston pin and 54.5mm bore are an issue. I do have a early RM rod that will fit the crank and would use a 14mm piston pin piston (CR125 1984?)

So many different things to try 😀


Cheers

Dave

[TZ350]

I did try " fixing " the T port by having the outer edges the highest , to ameliorate the huge difference in duct lengths the T suffers from.

354417 354418

Our interpretation of Woblys idea of having the outer edges of the T port the highest.

Not sure if this is correct, Wob and the Dyno will tell us soon enough I guess.

[wobbly]

Well it all depends upon what has changed , and thus if that change is an advancement.
If , by lifting the outer edges , you have also increased the port duration , then that will have the biggest effect on performance - especially if more timing/blowdown was needed to begin with.
But we all know the effect of excessive Ex timing , a big reduction in power spread.

Edit - is the outer edge hooked toward bore center properly ?

[TZ350]

- is the outer edge hooked toward bore center properly ?

Maybe not. Looking at your picture it looks like our efforts with the hook are to shallow. Will look at it again and dig more out if its needed. Thanks.

[wobbly]

Thank Frits , its his diagram of well known and long proven geometry.

[Frits Overmars]

Thank Frits , its his diagram of well known and long proven geometry.You are very welcome Wob.
As I wrote the other day, everything that I make available via https://1drv.ms/u/s!Atyzb5b7jtWNmVcX3c8D4Xr5eKjL?e=nxuw41
and via open forums such as KiwiBiker and Pit-Lane.biz, and even via Fakebook, may be freely used and distributed.

[SwePatrick]

Still developing my EFI setup, this week i changed the fuel strategy, far from done.
I´ll tune it today.
But it appears promising:


https://youtu.be/b22pSTwX0n4?si=_iR9EPb-f2d-C3Jf

[wobbly]

Having dyno and track tuned a 3YL/4DP TZ250 Yamaha to a win at Eastern Creek last weekend I have continued doing some development work for the future.
It has surprised the hell out of my by not responding in any way to the usual duct CSA reduction.
The stock exit is 37.5 dia and it likes nothing else except a 40 header forming a step. This increases front side and overev.
Its super finicky with intake length tuning and reed frequency , and will deto with even tiny increases in Com /MSV/Ignition/A/f or CE.
The other thing I wanted to nail down definitively is that for years many people have been extolling the virtues of cranks with cork in the balance holes , or full circle webs and or stuffing the case around the reed
to decrease the volume. I know both cases are not the same , but having measured one side and increased the volume to the usual 1.3 ratio , I now know this is all bullshit.
Sad really as the owner has a couple of super expensive filled and full circle cranks as well as a special kit version.
The pipe reacts as per normal , except it has to be alot shorter than I would expect to peak at 12500.
Its very difficult with the short stroke to get the needed STA , but its making the actual port power capability in the sim.
Anyway here is some info about the thing - Im now looking Hi and Low for a pair of 4DP - 11 or 4DP - 20 cylinders to put on it , please contact if anyone knows where a pair are hidding.

[F5 Dave]

So what are we looking at? The 70 hp looks right for a '91 B at rw. That's what Ansteys old one was on Chris's DJ they got it a bit better than that. I have the runs somewhere but don't even think I can run djpep without creating a virtual machine.
Sim looks like much higher revs. Is that what you are now aiming for ?

[wobbly]

Yes , the short stroke means the only way to generate power is by holding up the torque at much higher rpm.
13,000 is nothing to a 50.7 stroker.
The stock 3YL/4DP cylinders and pipes made max power of 75 @ about 11300 , and the solenoid powerjets just make it rev on forever.
Fast enough to win the class but nowhere near what is possible.

[Javier Ruda]

The pipe reacts as per normal , except it has to be alot shorter than I would expect to peak at 12500.

Hello wobbly, just an idea. When the fresh mixture must be pushed back in the cylinder it will find an exhaust port that is diminishing the height until it finally closes. Compared to a longer stroke engine the shape of that port could have a worse Cd on a short stroke engine because it will be not so “square”, needing an additional time to push back the mixture.

[katinas]

Having dyno and track tuned a 3YL/4DP TZ250 Yamaha to a win at Eastern Creek last weekend I have continued doing some development work for the future.
It has surprised the hell out of my by not responding in any way to the usual duct CSA reduction.
The stock exit is 37.5 dia and it likes nothing else except a 40 header forming a step. This increases front side and overev.


Hi Wobbly, could this be related to Yamaha 4DP more downward direction of ex duct. The roof angled down 22 degrees, the floor 42 degrees. And the floor angled down nearly from the cylinder wall, just about 3 mm off.

Other thing that looking so extreme from outside, is YZR 500 2001 exhaust duct arrangement.