ESE's works engine tuner

[wobbly]

Na, link is NFG

[Yow Ling]

Odd it works for me?
Is it the same for others?
There will not be much in there you have not seen before Frits:innocent:

Works for me , maybe you need a NZ passport?

[F5 Dave]

Not me. pretty sure I was born here.

[WilDun]

Doesn't work for me either, - maybe I shouldn't have said all those things about Telecom, - sorry, I mean Spark! - or is it my passport? Maybe I should have voted for Winston, I dunno.

[husaberg]

I will ask the Lord of the forum to look at it.
I way be a quirk of me being logged in and windows 8.
I am at work on W7 so i will try again
For some reason widows 8 will not let me post an embeded link in text either.

Later
Ok i have put the links in again this time using the link button rather than just picking them up as a url.
I have pm'ed Mr Trousers as well.
if not click on Husaberg go to albums.
I still have plenty of stuff to load but there is not much new, just easier for me to find stuff.


Later again
Ok this is what the site admin said...
IT's not KB, it's not me, its you......


The server is running perfectly fine and I've tried with 3 different browsers and they're all good too.

As long as the album is set to Public there shouldn't be any problem. If people are having problems it's usually something to do with filtering, either their ISP does some spam filtering and blocks them, or it's settings in their browser, or it's internet security type software.

Cheers.

Mr trousers.

NSR500
http://www.kiwibiker.co.nz/forums/album.php?albumid=4837
http://www.kiwibiker.co.nz/forums/album.php?albumid=4837

I will be adding some more later including
Honda RS125
http://www.kiwibiker.co.nz/forums/album.php?albumid=4841
http://www.kiwibiker.co.nz/forums/album.php?albumid=4841

Aprilia GP bikes
http://www.kiwibiker.co.nz/forums/album.php?albumid=4839
http://www.kiwibiker.co.nz/forums/album.php?albumid=4839

YZR500
http://www.kiwibiker.co.nz/forums/album.php?albumid=4845
http://www.kiwibiker.co.nz/forums/album.php?albumid=4845


Swiss auto
http://www.kiwibiker.co.nz/forums/album.php?albumid=4833
http://www.kiwibiker.co.nz/forums/album.php?albumid=4833

Rotax and other Tandem twins
http://www.kiwibiker.co.nz/forums/album.php?albumid=4840
http://www.kiwibiker.co.nz/forums/album.php?albumid=4840


RGV500

Kenny Roberts 3's

Cagiva
http://www.kiwibiker.co.nz/forums/album.php?albumid=4842
http://www.kiwibiker.co.nz/forums/album.php?albumid=4842

Carbs fuels intakes and stuff
http://www.kiwibiker.co.nz/forums/album.php?albumid=4844
http://www.kiwibiker.co.nz/forums/album.php?albumid=4844

If you can't get it to work click on husaberg (at the top of this post then view profile and then albums

[2T Institute]

Says those links are on the "dark side" I don't want to know what you have to do to get over there:lol:

[FastFred]

... click on Husaberg go to albums. I still have plenty of stuff to load but there is not much new, just easier for me to find stuff.

Great to have the pictures and hopefully magazine pages from you vast collection of posts in one easy accessible place.

[lodgernz]

[QUOTE=chrisc;1130773171]Today I found these somewhere deep in the ESE thread. Worthy of a repost I think.
Av on Scott's RSGP125 around Mt Welly.

Who's that on #88? Bit of a rocket

[FastFred]

Today I found these somewhere deep in the ESE thread. Worthy of a repost I think. Av on Scott's RSGP125 around Mt Welly.

Who's that on #88? Bit of a rocket

Nathaniel D, proving that you can be fast but to be first you first have to finish. A lap later you can see him picking himself up off the track.

Nathaniel is a very good up and coming rider with plenty of talent. It would be good to see him at the BOB.

[husaberg]

I ve got some Dentist bits if he wants them, l but they are tiny they would be more useful for drilling small items like teeth. :sweatdrop

Desaxe

I asked the panel a while back about offsetting cylinders ala YZF450 and Scott and Kawasaki ZX10R.


What i didn't know it comes from the steam age and a lot of aero engines were like this this is what i came up with today whist looking for something else.
I am still trying to model this with a 50mm 50 engine to see the results as my maths is crap and drawings are proving inaccurate.

http://en.wikipedia.org/wiki/Desaxe



http://ashonbikes.com/content/d%C3%A9sax%C3%A9-engines

http://www.iroquois.free-online.co.uk/merco/len.htm

And this
http://hellforleathermagazine.com/2010/12/free-power-offset-cylinders-explained/#more-13281

256340

And more curiously this on the Bantam thread.
http://bsabantamracing.editboard.com/t773-de-saxe-engine-configuration




Can Frits add some info to the RSA bit of the story?


(http://www.iroquois.free-online.co.uk/merco/len.htm)


(http://www.iroquois.free-online.co.uk/merco/len.htm)




PatAT Asymmetric Timing in Two-Strokes


300849

http://www.homebuiltairplanes.com/forums/2-stroke-aircaft-engines/18923-patat-asymmetric-timing-two-strokes.html

Asymmetric transfer timing, I have no idea if it works but its an interesting idea ....


Frits covered it further back........ Yamaha achieve it via offsetting the crankshaft and cylinder on quite a few modern bikes. ie YZF450
The port timing can be made asymmetric on a two stroke.
I think TZ ran the sim up to 12mm?


Up to 4mm would be easy to do, just mill the crankcase off-set and add some guide pins, more than that would need welding, but given the over-squareness of 54x44mm its a strange layout to work with, the exhaust pipes need much different sizes when compared to a more conventional square or almost square engine, the combustion chamber is also stranger and more difficult to react to some changes talked here.

I found it


Thanks for your reply Frits and Grumph I actually thought the offsetting might decrease the stroke but i guess my cockeyed math was a little crap.

But to save me stealing my kids compass and protractor would moving the cylinder forward or backwards actually have the same effect as the offset of the pin?
No doubt fits or wob can click a few keys on the keyboard? if not i will try to draw it out to see old school style. the 12mm offset did seem to make a meaningful difference on the sim with no other changes to spec to suit. it may have been a lot less reliablw though no doubt. Slapwise


Below is the Swiss Auto/ ELF/ ROC /MZ /Pulse V4 500 GP bike Bill Bucley has a Pulse 500 don't know if that has a ROC frame but i guess ir does.


If I remember correctly (1926 is some time back) the Garelli 350 Competizione was a split single allright, but unlike the later DKW split-single racers it did not have forked or articulated conrods. The Garelli was a normal 360° (both pistons rising and falling simultaneously) parallel twin with three transfer ports in the left cylinder and two exhaust ports in the right cylinder. Both cylinders shared a common combustion chamber. Each piston commanded two carburetters. Also unlike the DKWs, the Garelli had no auxiliary pump cylinder or blower of any kind.
I do like the look of the Garelli's exhaust pipes. It is the oldest bike I know of with such modern-looking pipes. Using diffusers to promote suction was not yet common practice then, and adding end cones would be regarded as revolutionary 26 years later! But I suspect that neither the exhaust timing nor the blowdown time.area of the Garelli did the end cones much justice; they were probably shaped like this just to accomodate the fish-tails.

I would not bother with offsetting cylinders or piston pins to achieve asymmetrical timing. The effect is very small and who needs the complication.
The pic below shows a calculation I did on the Aprilia RSA125. I gave it an offset of no less than 10% of the stroke in order to enhance the effect.
It is obvious that the maximum conrod angles become asymmetric. What may be less obvious, is the increase in piston stroke for a given crankshaft stroke!
It is also remarkable that it takes more than 180 crank degrees from TDC to BDC, and less than 180° from BDC to TDC.

Below is the sim Rob did it took bloody ages to find it.......

[Frits Overmars]

If you can't get it to work click on husaberg (at the top of this post then view profile and then albumsYeah, right:

vBulletin MessageInvalid Album specified. If you followed a valid link, please notify the administrator (http://www.kiwibiker.co.nz/forums/contact.php)

[husaberg]

Yeah, right:

vBulletin MessageInvalid Album specified. If you followed a valid link, please notify the administrator (http://www.kiwibiker.co.nz/forums/contact.php)


This is doing my head in Maybe I should remove the word porn from the post.
Maybe as mental said it is likely your security settings, there is nothing in their that is too dodgy other than the Yamahas and old British stuff?

[Frits Overmars]

This is doing my head in Maybe I should remove the word porn from the post. Maybe as mental said it is likely your security settingsI just checked: more porn than you can shake your stick at. So that's not it.

[richban]

Ignition timing.

I have a question re timing. At the moment 300 engine I am working with has plenty of timing at peak power. Like 14 degrees. I ran it for a race weekend and test day and then inspected the piston and head. All looked great. It was running strong cool and making the most power so far. My question is how much is to much. Is the old thinking of chuck in advance until it stops making power still valid or is there just a place you should not go. I ask this as I am fascinated with the cylinder head changes I made and wonder if we had put more advance in weather it would have brought the power back up. As the MSV was lower.

Cheers Rich.

[Yow Ling]

Ignition timing.

I have a question re timing. At the moment 300 engine I am working with has plenty of timing at peak power. Like 14 degrees. I ran it for a race weekend and test day and then inspected the piston and head. All looked great. It was running strong cool and making the most power so far. My question is how much is to much. Is the old thinking of chuck in advance until it stops making power still valid or is there just a place you should not go. I ask this as I am fascinated with the cylinder head changes I made and wonder if we had put more advance in weather it would have brought the power back up. As the MSV was lower.

Cheers Rich.

Maybe you should get a detonation sensor, then you will know when too much is, the other way is more destructive.
Do you have an ignitech? The det sensor box comes with an output that makes the ignitech retard a few degrees (or whatever you set) when it starts knocking. They cost $40 plus a sensor.
Cheap insurance

Ok they actually cost $68 http://www.ebay.com/itm/Knock-gauge-for-detonation-sensor-klopfsensor-NEW-/181309925670?pt=Race_Car_Parts&hash=item2a36e9e926&vxp=mtr

[wobbly]

The accepted norm for a race engine with everything well set up is 15* at peak power.
If you cant run this due to getting into deto, then its usually due to low com and or excessive squish velocity.
If it runs fine below this , then its screaming out to be advanced.
You have plenty of com for the fuel at 16:1, and the scavenging is not too bad,so if it likes more than 15* at peak then go looking for something that itsnt optimum.
My first guess is the carbs are too small, and or the reed area isnt sufficient for the big cylinder.
All mods are aimed at increasing the dynamic com, so getting more air in there will do this and end up limiting what can be achieved with advance.

[Yow Ling]

Hi Wob, could you explain what "excessive squish velocity "means

[richban]

The accepted norm for a race engine with everything well set up is 15* at peak power.
If you cant run this due to getting into deto, then its usually due to low com and or excessive squish velocity.
If it runs fine below this , then its screaming out to be advanced.
You have plenty of com for the fuel at 16:1, and the scavenging is not too bad,so if it likes more than 15* at peak then go looking for something that itsnt optimum.
My first guess is the carbs are too small, and or the reed area isnt sufficient for the big cylinder.
All mods are aimed at increasing the dynamic com, so getting more air in there will do this and end up limiting what can be achieved with advance.

Ok cool. The first heads the numbers all added up to 38 mvs at 11800. So good. With the new heads the squish was to big 0.12 so the numbers come in at 34 mvs at 11800. We tried pulling some advance out and it lost power straight away. So the lesson I take from this is find the mechanical squish limit the design the head around the limit. With brand spanking crank the other engine has run a .65/.7 squish and no sign of touching.

I do have a det sensor but have not installed it as yet. Will buy a long head stud this week and sort it.

It has some very short 38's YZ250. I was thinking about chucking some Vforce reeds in as new reeds are a good idea anyway.

I will pull the heads tonight and see what is what.

[richban]

Do you have an ignitech?

Yep yep.....

[wobbly]

In a NSR250 using VF3 is worth 4 Hp, and remember that the Aprilias ran 41/42mm carbs.
If the squish is very close and the width is too wide the MSV goes over 40M/Sec, this can and does limit peak and overev power considerably.
I would imagine the effect is caused by very high turbulence in the end gases, and this actually adds up to increased flame speed.
This is actually the same as having too much advance.
I have tried very high MSV with retarded spark to help make it rev and not deto, but this route looses alot of power.

[richban]

In a NSR250 using VF3 is worth 4 Hp, and remember that the Aprilias ran 41/42mm carbs.
If the squish is very close and the width is too wide the MSV goes over 40M/Sec, this can and does limit peak and overev power considerably.


Hummm. Also these barrels are quite close to stock. The engine has out preformed my expectations for sure. I am now itching to build another one but more carefully.

[Neal]

The husqvarna cr125 VF3 fits the nsr cases and the inlet stuffer is slightly less obtrusive than the honda cr125 one , but they both need to be shaped to mach the inlet rubbers .

[RomeuPT]

As above a Viton O Ring on the spigot face.I have had the oval to round transition made in alloy 7075 as well as some in simple mild steel.
Biggest issue is trying to get enough weld far enough into the duct,its a real bitch to get even a tiny Tig into the right places.
Im about to try some alloy stick welding rods, to build up the intake floor on a poxy Triumph 750 head,so this technique may save a hell of alot of drama.
The rods are only 3mm thick, so it should be easy to add material where needed, and even if it turns out a bit porous,its the shape that matters.

Wob, I am sorry for get back to this. I am thinking in build a spignot flange, instead of making pipes to fit direcly.

Is there any difference in performace or something else in making a mild steel instead of alloy? Or is just a question of wheight?

[richban]

My first guess is the carbs are too small, and or the reed area isnt sufficient for the big cylinder.


Sounds like a job for the flow bench. V force3 on the way as I need new reed's anyway.

[wobbly]

Alloy spigots wear out and leak in no time - even with a Viton O ring or two,in the female cup on the pipe.
Big thing to remember is getting water around the Ex port duct in the cylinder to keep it cool, even going to the lengths of drilling into the case
and getting water into the cylinder from under the Ex duct.
The very latest TM125 kart engine has only just had this homologated - 5 years behind as usual.

[F5 Dave]

jus' like my 1982 RG50.


which doesn't excuse a plethora of other design features.,.

[Bert]

The accepted norm for a race engine with everything well set up is 15* at peak power.
If you cant run this due to getting into deto, then its usually due to low com and or excessive squish velocity.
If it runs fine below this , then its screaming out to be advanced.
You have plenty of com for the fuel at 16:1, and the scavenging is not too bad,so if it likes more than 15* at peak then go looking for something that itsnt optimum.
My first guess is the carbs are too small, and or the reed area isnt sufficient for the big cylinder.
All mods are aimed at increasing the dynamic com, so getting more air in there will do this and end up limiting what can be achieved with advance.


Ok cool. The first heads the numbers all added up to 38 mvs at 11800. So good. With the new heads the squish was to big 0.12 so the numbers come in at 34 mvs at 11800. We tried pulling some advance out and it lost power straight away. So the lesson I take from this is find the mechanical squish limit the design the head around the limit. With brand spanking crank the other engine has run a .65/.7 squish and no sign of touching.

I do have a det sensor but have not installed it as yet. Will buy a long head stud this week and sort it.

It has some very short 38's YZ250. I was thinking about chucking some Vforce reeds in as new reeds are a good idea anyway.

I will pull the heads tonight and see what is what.

Igntech..

Yep yep.....


We should look at the base advance again to ensure that we are firing where we think we are.. Currently 14 degrees at peak power.

[wobbly]

Pick an advance number ( I usually use 28* that is the initial straight line on the ignition graph from 2000 up to say 7000 rpm ).
Convert this to mm down the bore, and use a DTI to set the piston exactly at this number.
Then arrange a scribe or white pen line on the rotor and stator that is easy to see with your strobe.
Fire it up and strobe the lines mechanically set at 28* holding the rpm steady between 2000 and 7000.
Adding more base timing will retard the firing line and visa versa.
This will ensure you are mechanically and electrically on the money in the Ignitech.
I have found that the only strobe that is dead accurate is the old, super el cheapo ones, that are in line with the plug leads.
Used to be $12.00 at Repco.

[Grumph]

In a NSR250 using VF3 is worth 4 Hp, and remember that the Aprilias ran 41/42mm carbs.
If the squish is very close and the width is too wide the MSV goes over 40M/Sec, this can and does limit peak and overev power considerably.
I would imagine the effect is caused by very high turbulence in the end gases, and this actually adds up to increased flame speed.
This is actually the same as having too much advance.
I have tried very high MSV with retarded spark to help make it rev and not deto, but this route looses alot of power.

Interesting....getting more diesel like all the time. Might be worth pursuing if you were limited either by regs or circumstance to crap fuel.
i'd have thought the hotter ex gas temps may have helped the pipe effects ?

[husaberg]

Sorry to interrupt this Honda love feast.
Swiss Auto Pulse ROC MUZ.
They had the flying web crank so were narrow.
Seeing as Wob and likely few others have seen the insides of one.
Was here charge robbing with the shared crankcase for the pars did not have the conrod shroud of the earlier pics I first seen.
Anyone got anymore pics of the internals.
It looks to me as if the engine was designed around the reed valve, Looks to be the best compromise with width vs cylinder spacing.

[husaberg]

Bit that didn't fit

[richban]

Pick an advance number ( I usually use 28* that is the initial straight line on the ignition graph from 2000 up to say 7000 rpm ).
Convert this to mm down the bore, and use a DTI to set the piston exactly at this number.
Then arrange a scribe or white pen line on the rotor and stator that is easy to see with your strobe.
Fire it up and strobe the lines mechanically set at 28* holding the rpm steady between 2000 and 7000.
Adding more base timing will retard the firing line and visa versa.
This will ensure you are mechanically and electrically on the money in the Ignitech.
I have found that the only strobe that is dead accurate is the old, super el cheapo ones, that are in line with the plug leads.
Used to be $12.00 at Repco.

Nice. On it. I pulled the head. Looks good no sign of anything dodgy. Honda Love fest continues.

TZ. You need to get you bike done. There are fancy 4 stroke buckets in sheds right now looking for the magic 30hp.

[TZ350]

TZ. You need to get you bike done. There are fancy 4 stroke buckets in sheds right now looking for the magic 30hp.


Yes, Buckets is getting very very interesting indeed, some really good looking bikes alright.

There is a secret (but legal) plan afoot at Team ESE, where we are looking for 40hp with a 6K power spread ..... :yes:

I can't point to any real proof that the idea works but I have heard anecdotal stories from reliable sources and a little bit of my own experience from back in the day.

The idea is so simple I am surprised other 2T's have not thought of using it, maybe didn't need to until now.

Its all about controlling the maximum temperature and pressure of the combustion process so the fire can be lit earlier. Then we can run a lower ultimate combustion pressure but higher average pressure over a longer period of time.

If it works I will show you what I have done when we have the next great Team ESE/GPR dyno shootout.

If not, then there is the Creasy engine project to get on with or the 100cc H2O 2T possibly CVT project (work on the prototype cylinder for this one is well advanced) and a CVT Supercharged 100cc H2O 4T project that I would love to do (the base bike for that project is sitting in the shed now).

Buckets ...... so much that is interesting, so little time..... :laugh:

A Team GPR 4T


http://i62.tinypic.com/r6w8cg.jpgktm all but ready to fire up

[Frits Overmars]

At the moment 300 engine I am working with has plenty of timing at peak power. Like 14 degrees... My question is how much is to much. Is the old thinking of chuck in advance until it stops making power still valid or is there just a place you should not go.
Maybe you should get a detonation sensor, then you will know when too much isA deto sensor will allow you to experiment with advanced timing values without losing the engine. But this doesn't mean that the maximum safe advance will be best for power; your engine may feel happier with a bit less advance than that. By the way, I don't regard 14° plenty of timing; I'd rather call it a decent neighbourhood.

[Frits Overmars]

...Its all about controlling the maximum temperature and pressure of the combustion process so the fire can be lit earlier. Then we can run a lower ultimate combustion pressure but higher average pressure over a longer period of time. That sounds quite intriguing. I'm not sure I would want to light the fire earlier; any pressure rise before TDC will slow the crankshaft down. And I'm not sure about that lower ultimate combustion pressure either. But I do see great possibilities with a lower compression ratio. A larger volume above the exhaust port will allow the pipe to stuff more charge back into the cylinder, and as the expansion ratio will also be lower, the pressure drop after TDC will be lower and the average pressure between TDC and Exhaust Open will be higher. And last but not least, there will be more exhaust gas energy left for the pipe to do nice things with.

[richban]

A deto sensor will allow you to experiment with advanced timing values without losing the engine. But this doesn't mean that the maximum safe advance will be best for power; your engine may feel happier with a bit less advance than that. By the way, I don't regard 14° plenty of timing; I'd rather call it a decent neighbourhood.

Yes totally agree. The det sensor is telling me nothing sitting on the bench. What sort of neighbourhoods have some of your engines lived in? The emphasis on the lived;)

[RomeuPT]

That sounds quite intriguing. I'm not sure I would want to light the fire earlier; any pressure rise before TDC will slow the crankshaft down. And I'm not sure about that lower ultimate combustion pressure either. But I do see great possibilities with a lower compression ratio. A larger volume above the exhaust port will allow the pipe to stuff more charge back into the cylinder, and as the expansion ratio will also be lower, the pressure drop after TDC will be lower and the average pressure between TDC and Exhaust Open will be higher. And last but not least, there will be more exhaust gas energy left for the pipe to do nice things with.

I love this stuff

[RomeuPT]

I wonder if this "GP based" kit did find this was the best pipe for it, the header doesn't seem to hamered also

http://www.maxiscoot.com/media/catalog/product/cache/3/image/273fe73c516cc2b029d5af29aaf1e15a/m/x/mxsgp002p2_01_5.jpg

http://www.maxiscoot.com/media/catalog/product/cache/1/image/80bd357319c20826b2d9c3b8cfea3972/m/x/mxs385_a13_1.jpg

[bucketracer]

That sounds quite intriguing.

40hp ... its probably a bit of a tease.

But then when TeeZee started out nobody expected he would do 31hp either, 20hp being more the class norm, so 40? who knows ....:scratch:

Come to think of it, he is now working with a cylinder that has transfer port area to burn, an exhaust port that can be made as big as a Honda RS125's, a good pipe, and a power valve setup, he has found a way to nullify the restriction of a 24mm carb, he has a programmable ignition with TPS and a bunch of his own ideas like the variable inlet pipe area, and pipe pressure dropper. So he has put the tools together to work with.

Air cooling is the big issue I guess ....

[wax]

Hey guys I'm trying to get hold of a bucket racer in nz
Simion yule
I know he raced against you guys. Do any of you guys have his contact.
Thanks

[Flettner]

40hp ... its probably a bit of a tease.

But then when TeeZee started out nobody expected he would do 31hp either, 20hp being more the class norm, so 40? who knows ....:scratch:

Come to think of it, he is now working with a cylinder that has transfer port area to burn, an exhaust port that can be made as big as a Honda RS125's, a good pipe, and a power valve setup, he has found a way to nullify the restriction of a 24mm carb, he has a programmable ignition with TPS and a bunch of his own ideas like the variable inlet pipe area, and pipe pressure dropper. So he has put the tools together to work with.

Air cooling is the big issue I guess ....

I think a water cooled 100 is also on the go, I think 40HP is not out of the question although it will be a completely new engine, not a modified street bike. The technology to do this is all layed out on this forum, just need to do it. TZ is no mug, a little more effort might be going on than you see on this forum. Who knows, a twin might not be out of the question?

[Yow Ling]

I think a water cooled 100 is also on the go, I think 40HP is not out of the question although it will be a completely new engine, not a modified street bike. The technology to do this is all layed out on this forum, just need to do it. TZ is no mug, a little more effort might be going on than you see on this forum. Who knows, a twin might not be out of the question?

And all the children followed the pied piper

The limits applied to GP125's dont apply to buckets , so I guess there are a few things that will allow these targets to be met, Twin cylinder you say, why not a triple?

[F5 Dave]

Hell why stop there? Look how well it worked for shaver blades:lol:

[lodgernz]

Frits, your FOS concept for pipes has been around for a long time and has been seen by millions, but I have never seen anyone question your formula for the "tuned length".

302400

Your formula is: Lmax = Speed of Sound * exhaust timing * 88 / RPM of max power

By my maths, the "88" should be 1000/12 ie 83.3333....

I assume your formula is allowing for some other factor, perhaps the higher speed of sound in the exhaust pipe, and I'm curious to know your logic.

[senso]

Frits, your FOS concept for pipes has been around for a long time and has been seen by millions, but I have never seen anyone question your formula for the "tuned length".

302400

Your formula is: Lmax = Speed of Sound * exhaust timing * 88 / RPM of max power

By my maths, the "88" should be 1000/12 ie 83.3333....

I assume your formula is allowing for some other factor, perhaps the higher speed of sound in the exhaust pipe, and I'm curious to know your logic.

Why/were do those 1000/12 come from, I'm curious now.

[TZ350]

http://youtu.be/sMKc5R8ZEeg?list=UUg1Ze1muy87n3mkhOHMXVSg

That Sir, is a seriously serious looking bike, I had better get a move on, Team ESE's 2T's are being left behind.

[lodgernz]

Why/were do those 1000/12 come from, I'm curious now.

At R rpm, one rev takes 60000/R ms.
E degrees, the exhaust duration from EO to EC, takes E/360 of a rev.
So, rotating the crank through E degrees takes (60000 * E) / (360 * R) ms. = (1000 * E) / (6 *R).

The distance travelled by a wave at the speed of sound S in this time is
S * (1000 * E) / (6 * R) or 166.666 * S * E / R
At Rmax, we want this to be the time for this wave to reach the end of the baffle cone and return to the cylinder,
hence the distance from cylinder to baffle cone must be half the distance travelled by the wave,
i.e. 83.333 * S * E / R

Pretty sure...

[TZ350]

Frits, your FOS concept for pipes has been around for a long time and has been seen by millions, but I have never seen anyone question your formula for the "tuned length".

302400

Your formula is: Lmax = Speed of Sound * exhaust timing * 88 / RPM of max power
By my maths, the "88" should be 1000/12 ie 83.3333....
I assume your formula is allowing for some other factor, perhaps the higher speed of sound in the exhaust pipe, and I'm curious to know your logic.

The distance travelled by a wave at the speed of sound S in this time is

S * (1000 * E) / (6 * R) or 166.666 * S * E / R

I think you are right, the answer is in the "Speed of Sound", because its the speed of sound at what temperature?

And the temperature, it is variable along the pipe, and the wave travels faster in the regions of higher temperature.

What is the average gas temperature you are using for your pipe calculations?

If I am right about this, hopefully we will both get a chocolate fish.

[Drew]

The speed of sound is relative to density, no? The temperature is indicative of that, but not perfect. The material that the waves are bouncing off and reducing at the same time is changeable too with being welded and stressed.

Is it possible to bypass the pipe fuckery and fire a pulse back up the exhaust port of ones own creation? Make it of a register so low it is barely perceptable, and the volume of the bike stays nice and civil.

Just a thought. Might go and mount a subwoofer and amp to the GT and see what happens.

[Bert]

That Sir, is a seriously serious looking bike, I had better get a move on, Team ESE's 2T's are being left behind.

Watch closely how the frame / suspension responds to being loaded up... No squatting in the backend under acceleration. Well done Scott, those frame modifications have made it even better.
:2thumbsup

[Drew]

Watch closely how the frame / suspension responds to being loaded up... No squatting in the backend under acceleration. Well done Scott, those frame modifications have made it even better.
:2thumbsup

Some squat is accepted as an absolute must on proper bikes. If it is tuned out with a steep swingarm such as that bike, the drive force is fighting the suspension and you sacrifice traction.

Might be alright with twenty or thirty ponies to ride (but could be better), but pump a hundred and ninty through the tread and things get...interesting on corner exit.

[lodgernz]

I think you are right, the answer is in the "Speed of Sound", because its the speed of sound at what temperature?

And the temperature, it is variable along the pipe, and the wave travels faster in the regions of higher temperature.

What is the average gas temperature you are using for your pipe calculations?

If I am right about this, hopefully we will both get a chocolate fish.

I think the SoS in air is around 331m/s, and at 480* it's around 550m/s.
That's the figure I usually use, but maybe Frits is already factoring that into his formula, and expects us to use the SoS in air.
Can't eat choc fish. Hurts my knackered old teeth.

[husaberg]

I think the SoS in air is around 331m/s, and at 480* it's around 550m/s.
That's the figure I usually use, but maybe Frits is already factoring that into his formula, and expects us to use the SoS in air.
Can't eat choc fish. Hurts my knackered old teeth.

When Frits posted it He said something along the lines of....... it was meant to be a simple formula to put you in the ball park.
He said the more complicated formula he uses is based on complex data and measurements
but no matter how complicated it will still need testing and verification.

[Flettner]

So, if your 150 will rev to 14000 and you have a BMEP of 247.6 (that would have to be an absolute max), you will see 40HP. Probably revs higher and BMEP a little lower in reality.

100cc, if it was up to the Aprilia 125 BMEP ( 211.85 ) would produce 44HP at 13500 RPM.
These calculations are just out of Graham Bells book, so just a good guide.
My Aprilia BMEP figure might be a little high as I calculated it at 55 HP, 13500 RPM.

If the 100cc twostroke was a twin, say, and reved to 15500, you might see 50 / 51 ish HP
The truth is trying to get these BMEP's would be very difficult.

So lets supercharge our 100cc fourstroke say 365.5 BMEP? at say ( it's a twin ) 16000 rpm,
45HP.

Just some random figures I know but never the less interesting.

[TZ350]

Interesting numbers all right, yes once 20hp was considered good and divided the pretty good from the average, now it seems that the benchmark is going to become 30hp.

[husaberg]

Interesting numbers all right, yes once 20hp was considered good and divided the pretty good from the average, now it seems that the benchmark is going to become 30hp.

Honda did 150hp out of a 250 turbo twin at the first try.......scary just as well all the stuff to do this is unavailable unless custom.
Just as well 50hp would be useless on a kart track as well, look at the f4 vs f5 times

[cotswold]

Frits, your FOS concept for pipes has been around for a long time and has been seen by millions, but I have never seen anyone question your formula for the "tuned length".

302400

Your formula is: Lmax = Speed of Sound * exhaust timing * 88 / RPM of max power

By my maths, the "88" should be 1000/12 ie 83.3333....

I assume your formula is allowing for some other factor, perhaps the higher speed of sound in the exhaust pipe, and I'm curious to know your logic.

I had the same issue and was told sounds travel faster in hot air

http://www.thenakedscientists.com/forum/index.php?topic=11505.0

http://www.sengpielaudio.com/calculator-speedsound.htm

I do have the number used somewhere but can't find it. I was told to reverse calculate it

[Frits Overmars]

When Frits posted it He said something along the lines of....... it was meant to be a simple formula to put you in the ball park. He said the more complicated formula he uses is based on complex data and measurements but no matter how complicated it will still need testing and verification.Husa, your memory serves you well.

The 'FOS exhaust concept' is only meant to help beginning tuners on their way.A lot of important factors, like compression ratio, ignition timing, type of fuel, carburetter diameter, crankcase volume and angle.areas, are not taken into account.
Instead of all those factors that I left out, I included one variable, the speed of sound. Starting with 550 m/s will get you in the right ballpark, after which you can vary this value according to your findings.
You should not use this simple exhaust concept to improve on the highly developed RSA engine, where all of the above-mentioned factors were taken into account.
Final remark: the calculation of the tailpipe restrictor diameter is critical: you can only apply it to engines that are thermally sound. Air-cooled engines are not.TZ, would you settle for a chocolate teapot?

[wobbly]

Lets quote real figures for what can be achieved with a genius called Thiel in charge of over 100 people in a race dept R&D facility.
The best an RSA made was 58 crank Hp ( assume +5% over sprocket dyno power ) at 13000 rpm.
This is 16 Bar ( 232 psi ) bmep at the crank - here is the sim graph.
Take that bmep and apply it to a 100cc water cooled with 50 by 50 bore stroke.
Assume peak power at 14,000 ( easy ) and we have 49 crank - less 12% to read on a Dynojet and thats 43 RWHP.
No trick shit technology,no weird ideas, just great attention to every detail.
Can it be done, for sure, just not when you start with a 30 year old crankcase and an iron sleeve in a road bike 125 cylinder.

[richban]

Lets quote real figures for what can be achieved with a genius called Thiel in charge of over 100 people in a race dept R&D facility.
The best an RSA made was 58 crank Hp ( assume +5% over sprocket dyno power ) at 13000 rpm.
This is 16 Bar ( 232 psi ) bmep at the crank - here is the sim graph.
Take that bmep and apply it to a 100cc water cooled with 50 by 50 bore stroke.
Assume peak power at 14,000 ( easy ) and we have 49 crank - less 12% to read on a Dynojet and thats 43 RWHP.
No trick shit technology,no weird ideas, just great attention to every detail.
Can it be done, for sure, just not when you start with a 30 year old crankcase and an iron sleeve in a road bike 125 cylinder.

And this is why I am now building a 2 stroke bucket. We are nearly at 300hp pre litre with the heavy piston over square 300. The power to weight just can't be beat. I am converted.

[wobbly]

Drew is right about having so much anti squat the bike rises and pulls against the tiedowns on the dyno.
All this is good for is stopping dyno wheelspin.
I made that mistake with the Frepin TZ400.
As it was setup it had too much anti squat, via the swingarm angle.
Around the sweeper at PI it would step out the rear when Discombe powered it into a 2 wheel slide.
I dropped the rear 10mm ,as much as I could on the Ohlins mono shock,and it would then almost take full power in a controlled slide
all the way onto the front straight.
Denis is about to shorten the shock so it can be dropped a little more, so then it can be set up each side of pro or anti squat in testing.

[husaberg]

And this is why I am now building a 2 stroke bucket. We are nearly at 300hp pre litre with the heavy piston over square 300. The power to weight just can't be beat. I am converted.

Insert that's a big decision comment here:lol:

[richban]

Insert that's a big decision comment here:lol:

How are those barrels coming alone Husa? Do they have honda power valves?

[husaberg]

How are those barrels coming alone Husa? Do they have honda power valves?

No slide blade 2 stage, like an Aprilia.
You still have the RGV as well?
That they will fit nicely.

[richban]

You still have the RGV as well?
That they will fit nicely.

No no Honda all the way.

[husaberg]

No no Honda all the way.

Oh just like Dave............

[richban]

Oh just like Dave............

Ah no. A lot different. The bottom end will be from this decade.

[husaberg]

Ah no. A lot different. The bottom end will be from this decade.

it was a Honda joke, are you planning on using a nsr150 bottom end?

[richban]

it was a Honda joke, are you planning on using a nsr150 bottom end?

Yep. Any idea what the weigh? good gearbox apparently.

[husaberg]

Yep. Any idea what the weigh? good gearbox apparently.

About 22 kg from memory. Nice motor Not sure where Bren is at with his. But it will be further along than me.:laugh:

Nsr125 89-91

Transmission 6 speeds constant mesh
Primary reduction 3.250 (65/20)

Gear ratio:
1st 3.090 (34/11)
2nd 2.000 (30/15)
3rd 1.470 (25/17)
4th 1.210 (23/19)
5th 1.043 (24/23)
6th 0.916 (22/24)

Honda NSR150SP
Primary reduction 2.954 (65/22)
Final reduction 2.857 (40/14)
Gear ratio 1st 2.916 (35/12)
Gear ratio 2nd 1.937 (31/16)
Gear ratio 3rd 1.470 (25/17)
Gear ratio 4th 1.210 (23/19)
Gear ratio 5th 1.043 (24/23)
Gear ratio 6th 0.916 (22/24)

the crank in the Nsr150 is beefier apparently the primary drive is a different ration which I never noticed before.
There is also a CRM125 variant of the same engine which I think has different ratios again. either that or there is some variation in the rations of the NSR125.


NSR250
Also ere is the gearbox ratios and part number for the ratios that fit NSR250 anyway I seen these the other day and saved it.Note most are RS250 part codes.

[TZ350]

TZ, would you settle for a chocolate teapot?

302513


Yep ...... yum.

[TZ350]

Just as well 50hp would be useless on a kart track as well, look at the f4 vs f5 times

30hp is pretty useless on the Mt Wellington Kart Track too, well in my hands anyway. As its mostly cornering, very little opportunity for stretching the legs. But it is a different hp story at the bigger tracks. Hopefully we will have a decent chassis soon using the frame you gave us. The CVT project has not been shelved and is next in line, it will be interesting to see how that goes on a tight track.

[mr bucketracer]

Drew is right about having so much anti squat the bike rises and pulls against the tiedowns on the dyno.
All this is good for is stopping dyno wheelspin.
I made that mistake with the Frepin TZ400.
As it was setup it had too much anti squat, via the swingarm angle.
Around the sweeper at PI it would step out the rear when Discombe powered it into a 2 wheel slide.
I dropped the rear 10mm ,as much as I could on the Ohlins mono shock,and it would then almost take full power in a controlled slide
all the way onto the front straight.
Denis is about to shorten the shock so it can be dropped a little more, so then it can be set up each side of pro or anti squat in testing.you better tell mr honda he don't know what hes doing:facepalm:

[mr bucketracer]

Some squat is accepted as an absolute must on proper bikes. If it is tuned out with a steep swingarm such as that bike, the drive force is fighting the suspension and you sacrifice traction.

Might be alright with twenty or thirty ponies to ride (but could be better), but pump a hundred and ninty through the tread and things get...interesting on corner exit.if only you new what you are talking about

[Drew]

you better tell mr honda he don't know what hes doing:facepalm:Could you offer something to suggest that Honda tune out 'squat' with big swingarm angle?


if only you new what you are talking aboutThat's quite inflammatory, my experience with this subject is more extensive than most. Care to spell out where I was wrong?

The big angle can be fine, so long as the front sprocket is high and the line between axle, swinging arm pivot, and front sprocket centre are close to in line with the rider on it.

But the geometry of the bike is effected more with big compression, ie when the bike is leaned over and there's large g's acting on the suspension. This could be used to an advantage I suppose. By crikey there'd be a shit ton of testing and data logging to paw through. In real terms I expect GP is the only environment that would or has happened.

[Kickaha]

if only you new what you are talking about

If only you could spell.

[husaberg]

If only you could spell.

If only any of you were a good looking as me.:rolleyes:
I have posted the pro anti squat before it Is a balancing act and comes down to preferences there is no 100% right or wrong. (Other than I am pretty)

[mr bucketracer]

Could you offer something to suggest that Honda tune out 'squat' with big swingarm angle?

That's quite inflammatory, my experience with this subject is more extensive than most. Care to spell out where I was wrong?

The big angle can be fine, so long as the front sprocket is high and the line between axle, swinging arm pivot, and front sprocket centre are close to in line with the rider on it.

But the geometry of the bike is effected more with big compression, ie when the bike is leaned over and there's large g's acting on the suspension. This could be used to an advantage I suppose. By crikey there'd be a shit ton of testing and data logging to paw through. In real terms I expect GP is the only environment that would or has happened.we are talking about the bike in the video not tz400 etc , the bike is built for bucket tracks diffient from standard track , i dont got looking for shit on the net and post it. i go for what a have learn't building frames and racing and there is aways more to learn , i look at it as the rear end rise's it pushes the rear into the track whichs keeps the front on the ground for better turning( not running wide). as g forses come into afeck and diffent weights of the bike it will change ( heavy bikes more lightly to swat but a well set bike like motor gp bike look to sit neutral . i dont have the time to sit her blabing on as i have bike to build and learn more . think about what i have put? , i raced guys bikes over the years that say there bike it sliding out , doing all sort of crap , i ride it , go 5 seconds a lap faster and think it go's like a dream . best to get out on the track and do what suit you to go fast

[steamroller]

If only you could spell.

john britten could not spell he just got on and did it. to much talk from some people and no do

[Drew]

If only any of you were a good looking as me.:rolleyes:
I have posted the pro anti squat before it I a balancing act and comes down to preferences there is no 100% right or wrong. (Other than I am pretty)As is the case with every single aspect of suspension and geometry of a motorcycle. They cannot be built to do everything to it's potential.

[Drew]

john britten could not spell he just got on and did it. to much talk from some people and no do

Yeah, and his bike rode like a fucken pig.

[steamroller]

If only any of you were a good looking as me.:rolleyes:
I have posted the pro anti squat before it I a balancing act and comes down to preferences there is no 100% right or wrong. (Other than I am pretty)

bang on if you can win with what your on its working

[steamroller]

Yeah, and his bike rode like a fucken pig.

did you ride it

[Drew]

did you ride it

Of course not. Good riders with oodles of talent did instead. They say pretty much the same thing, power to weight ratio is where it's advantage started and ended.

[steamroller]

Of course not. Good riders with oodles of talent did instead. They say pretty much the same thing, power to weight ratio is where it's advantage started and ended.

fuck up then:tugger:

[Drew]

fuck up then:tugger:

This thread is a resource for people building bikes. Loads of people share what they have learned through experience.

Try to keep the trolling to other threads thanks.

[lodgernz]

Husa, your memory serves you well.
TZ, would you settle for a chocolate teapot?

OK. Guess I'll keep using the correct formula with 83.3 and 550m/s.
Thanks very much for the other tips in this forum, especially Frits and Wobbly, it's been pretty amazing.

[wobbly]

" as the rear end rise's it pushes the rear into the track whichs keeps the front on the ground for better turning".

Thats dead correct except its back to front thinking in my opinion.
If you have an issue with running wide on exit then you need to look at gaining some front end turn - drop the forks thru.
Gaining front grip by killing the rear end with anti squat does "work " but in the example I gave with the Frepin, it was loosing rear grip under power when tipped over hard.
So I didnt try to fix that by reducing the front grip, I dialled in some more natural rear grip by reducing the anti squat % - dropping the rear ride height.
This works just as well around the sweeper at Mt Welly where even at those slow speeds the suspension is heavily compressed.
No Mates bike initially used to step the back out when leaned over going as hard as he could around the sweeper.
Dropping the back gained some rear grip by reducing the anti squat.
It then started to run wide on turn in,so rather than reduce the good rear grip we had just gained he dropped the forks thu to steepen up the front.
Now it steered, and had rear edge grip - seemed to work OK, he won on Mt Welly 3 years in a row.

Same idea with Discombs TZ350 around Hampton when he won the Sheene last year.
It was pattering and loosing front grip when hard over exiting the sweeper under power - that bike has near on no anti squat at all, so all we could do was reduce the squat by winding in
a heap of preload and a couple of compression clicks.
This stopped the rear from squatting so much and unloading the front - then it steered at full noise onto the front straight - seemed to work, he was 3 secs a lap faster than anyone in his class.

Its always best to try and gain grip to balance out a lack at one end, reducing the grip at the opposite end can and does work - if that all that can be done to fix pig handling.

[TZ350]

About 22 kg from memory. Nice motor Not sure where Bren is at with his. But it will be further along than me.:laugh:

Nsr125 89-91

NSR125 project:- http://thetrxproject.blogspot.co.nz/2013/06/nsr-update-mounting-engine.html

[Bert]

Of course not. Good riders with oodles of talent did instead. They say pretty much the same thing, power to weight ratio is where it's advantage started and ended.
Really? Jason never complained, quite sure Andrew never made those claims...
Whom are you referring to Drew?


This thread is a resource for people building bikes. Loads of people share what they have learned through experience.
Try to keep the trolling to other threads thanks.

Yip, and tried to add as much as we can.
I actually thought it was an interesting thing to discuss.
Given late model RS125s and TZ125s tend to show this as well.
The GPR frames feel great on track.
Streamroller, your only 3rd in NZ (two years in a row) what would you know.
And don't worry about Glen Williams SVR650....

Wobs post above makes good sense, I can imagine that the more mass (weight) and more power - loads up the front with too much anti squat and if front end is not setup to deal with it then it will all go pear shaped.

Owell we will stay away.

[Drew]

Yip, and tried to add as much as we can.
I actually thought it was an interesting thing to discuss.
Given late model RS125s and TZ125s tend to show this as well.
The GPR frames feel great on track.
Streamroller, your only 3rd in NZ (two years in a row) what would you know.
And don't worry about Glen Williams SVR650....

Wobs post above makes good sense, I can imagine that the more mass (weight) and more power - loads up the front with too much anti squat and if front end is not setup to deal with it then it will all go pear shaped.

Owell we will stay away.It's not the front that it goes pear shaped at. The rear lets go in a hell of a hurry, because the suspension isn't working due to the torque fighting it. So there's no give and when it hits a bump the wheel leaves the ground.

The distance between the two sprockets is at it's greatest when the swingarm pivot and sprocket centers are all in a straight line. When you put the rear sprocket lower than that straight line and apply the gas, the torque is trying to pull that sprocket forward by shortening the distance more as the swingarm further extends.

Loading a tyre more is the goal, bump compliance is the unfortunate requirement for suspension.

[F5 Dave]

" as the rear end rise's it pushes the rear into the track whichs keeps the front on the ground for better turning".

Thats dead correct except its back to front thinking in my opinion.
If you have an issue with running wide on exit then you need to look at gaining some front end turn - drop the forks thru.
Gaining front grip by killing the rear end with anti squat does "work " but in the example I gave with the Frepin, it was loosing rear grip under power when tipped over hard.
So I didnt try to fix that by reducing the front grip, I dialled in some more natural rear grip by reducing the anti squat % - dropping the rear ride height.
This works just as well around the sweeper at Mt Welly where even at those slow speeds the suspension is heavily compressed.
No Mates bike initially used to step the back out when leaned over going as hard as he could around the sweeper.
Dropping the back gained some rear grip by reducing the anti squat.
It then started to run wide on turn in,so rather than reduce the good rear grip we had just gained he dropped the forks thu to steepen up the front.
Now it steered, and had rear edge grip - seemed to work OK, he won on Mt Welly 3 years in a row.

Same idea with Discombs TZ350 around Hampton when he won the Sheene last year.
It was pattering and loosing front grip when hard over exiting the sweeper under power - that bike has near on no anti squat at all, so all we could do was reduce the squat by winding in
a heap of preload and a couple of compression clicks.
This stopped the rear from squatting so much and unloading the front - then it steered at full noise onto the front straight - seemed to work, he was 3 secs a lap faster than anyone in his class.

Its always best to try and gain grip to balance out a lack at one end, reducing the grip at the opposite end can and does work - if that all that can be done to fix pig handling.

niges real problem is the spring at the rear is too soft for his fat arse. I spent a bunch of time watching at the last GP as my bike had welded it's clutch. And you could see it going full stroke and stepping dread fully at Tokaroa which is a severe track. He hadn't noticed but was still frothing at the mouth post race. Ahh we're all getting too old. To be fast again.

[TZ350]

I actually thought it was an interesting thing to discuss.

Me too, as its a topic I am going to have to learn more about.

So as I understand it so far (and probably incorrectly):-

If the back squats down under power it puts more weight and therefor traction on the back wheel and un loads the front. Un loading the front under power can allow the bike to run wide.

Ant squat or the back rising up transfers weight to the front wheel for front end grip when turning in and with less weight on the back, the back could tend to slide out.

Because its been our habit to tie the bikes down so tight on the dyno I have not really observed if ours squat or otherwise, interesting that we can use a run on the dyno to observe changes made to this part of the suspension setup.

[wobbly]

What many forget is that there is a finite mass of bike and rider.
Using antisquat to transfer some of that finite amount to the front - MUST by definition reduce the rear.
Less or neutral anti squat by dropping the ride height and the swingarm angle ,allows more weight transfer to the rear - increasing grip at that end.
The anti squat rising force is an internal frame vector, the actual result of the frame rising ( thus the rear wheel pushing down ) is weight transfer off
the rear and onto the front - counter intuitive I know, but increased FRONT grip is what actually happens in the end.
Add to that the dramatic increase in effective rear bump rate under power, and anti squat although intellectually an obviously useful tool, suddenly becomes a very sharp double edged sword.

[wobbly]

One thing to be careful of TeeZee is that the rear wheel will try to climb up the dyno roller under power - giving the illusion of a big anti squat %.
To get an idea of the squat rate you have to be aware of the wheel position.

[TZ350]

One thing to be careful of TeeZee is that the rear wheel will try to climb up the dyno roller under power - giving the illusion of a big anti squat %. To get an idea of the squat rate you have to be aware of the wheel position.

Thanks for the tip.

302649

I can see the possibility of a headache coming on, while trying to get to grips with understanding suspension tuning.

[Drew]

Get the spring rate right, set he sag with rider, and static the swingarm should be pointing close to the middle of the front sprocket or slightly above.

Adjust the tendency to run wide or tip too fast with fork height. This is the start point. From it you are in the crazy land of suspension damping, and the endless trade offs you are forced to deal with.

You're pissing in the wind with the wrong springs.

Have fun.

[mr bucketracer]

Me too, as its a topic I am going to have to learn more about.

So as I understand it so far:-

If the back squats down under power it puts more weight and therefor traction on the back wheel and un loads the front. Un loading the front under power can allow the bike to run wide.

Ant squat or the back rising up transfers weight to the front wheel for front end grip when turning in and with less weight on the back, the back could tend to slide out.

Because its been our habit to tie the bikes down so tight on the dyno I have not really observed if ours squat or otherwise, interesting that we can use a run on the dyno to observe changes made to this part of the suspension setup.squat with ant squat working together is what gives traction , remove ant squat out of it and let it squat under power will i think go from unloaded to overload as it bottoms out , i bit of both is a good controlable ride

[Moooools]

What many forget is that there is a finite mass of bike and rider.
Using antisquat to transfer some of that finite amount to the front - MUST by definition reduce the rear.
Less or neutral anti squat by dropping the ride height and the swingarm angle ,allows more weight transfer to the rear - increasing grip at that end.
The anti squat rising force is an internal frame vector, the actual result of the frame rising ( thus the rear wheel pushing down ) is weight transfer off
the rear and onto the front - counter intuitive I know, but increased FRONT grip is what actually happens in the end.
Add to that the dramatic increase in effective rear bump rate under power, and anti squat although intellectually an obviously useful tool, suddenly becomes a very sharp double edged sword.

Could you explain where this increased grip on the front wheel is coming from?

Anti squat causes an increase i frame height (or in reality pitches the bike forward) when accelerating. Under steady acceleration the only affect this will have is to raise the COG height of the bike+rider, which will increase normal load on the rear wheel (due to pitching moment from acceleration), and take it off the front - more rear grip, less front.

Under a transient acceleration (acceleration of acceleration) the chassis will be accelerated upwards, and a reaction force will be seen at the rear wheel (D'Alembert's principle). This reaction force stops when the acceleration becomes steady or begins decreasing. This is more often a smoother affair and is unlikely to happen during a corner. So - More rear grip followed by maybe less rear grip if you decide to shut the throttle.

I am struggling to see in all this a reason for the front wheel to see increased grip. What am I missing?

EDIT: Is it inertial moments causing the bike to pitch about some point ahead of the COG, causing a larger reaction force at front wheel due to a shorter moment arm? That would mean that the motion increases load on both wheels (but more so at the front) and the reverse motion (springing back to neutral position) unloads both wheels. (Not sure I explained that too well)

[Drew]

squat with ant squat working together is what gives traction , remove ant squat out of it and let it squat under power will i think go from unloaded to overload as it bottoms out , i bit of both is a good controlable rideThe spring is constantly pushing the wheel onto the road. Corectly sprung you should be able to tune with damping for nearly any track.

Antisquat is getting to the uppermost technical side of suspension tuning. 99% of riders need never worry about it unless they get a bike that's been set up too high to begin with.

[Drew]

Could you explain where this increased grip on the front wheel is coming from?

Anti squat causes an increase i frame height (or in reality pitches the bike forward) when accelerating. Under steady acceleration the only affect this will have is to raise the COG height of the bike+rider, which will increase normal load on the rear wheel (due to pitching moment from acceleration), and take it off the front - more rear grip, less front.

Under a transient acceleration (acceleration of acceleration) the chassis will be accelerated upwards, and a reaction force will be seen at the rear wheel (D'Alembert's principle). This reaction force stops when the acceleration becomes steady or begins decreasing. This is more often a smoother affair and is unlikely to happen during a corner. So - More rear grip followed by maybe less rear grip if you decide to shut the throttle.

I am struggling to see in all this a reason for the front wheel to see increased grip. What am I missing?

This is getting fucking stupid.

With the rear shock unable to compress, as soon as the tyre reaches the top of a bump YOU LOSE TRACTION. Not gain it.

Ps. Weight distribution is where tye extra front grip comes from. But it is important to realise that this is a different part of the turn. Corner entry is where raising the rear gives more front grip, the trade off being less exit grip at the rear.

[Moooools]

This is getting fucking stupid.

With the rear shock unable to compress, as soon as the tyre reaches the top of a bump YOU LOSE TRACTION. Not gain it.

Ps. Weight distribution is where tye extra front grip comes from. But it is important to realise that this is a different part of the turn. Corner entry is where raising the rear gives more front grip, the trade off being less exit grip at the rear.

Anti squat doesn't remove the ability for the rear shock to compress though , unless you were to run a shit tonne of it and topped the shock out. The spring can still compress just the same, it is just sitting higher than it was.
Bumps aren't the only transient concern on a motorcycle. In fact they are a pretty small factor compared to inertial loads when you are riding around on billiard tables i.e. a racetrack.

[wobbly]

Wrong - anti squat force is obtained by the chain trying to pull the rear wheel forward, or put another way - to shorten the swingarm.
When the swingarm is at an acute downward angle, as the chain pulls harder the resultant anti squat reaction forces the rear of the bike upward.
By the obvious physics of action and equal re action, then rear wheel is being pushed downward at the same time with the same force value.
Thus it is this reaction force ( an internal frame force ) that prevents a bump or track ripple from compressing the rear shock, via the rear wheel rising
in relation to the seat height.
So although the shock/spring combination may actually physically able to compress, it cant due to the high internal frame force trying to lengthen the shock.
When in this powered on state, a bump will have to lift the rear of the bike AND the riders bum mass as well, this is not called suspension, its called a jolt in the arse
closely followed by an instantaneous slide, closely followed probably by a highside - they hurt.
To prove any theory, go to the nth degree.
With a lot of pro squat dialled in via front sprocket height, and or swingarm angle - under power on conditions ultimately ALL the bike/rider mass will be transferred to the rear tyre.
ie a wheelstand.
Watch MotoGP today and on virtually every corner exit the front tyre is just off the deck, thus they have just enough weight transfer ( and auto Hp control ) to give the absolute
maximum rear grip available - the front tyre is off the ground, directional control is then only via counter-steering and rider weight.

[TZ350]

302661

Squat Anti Squat


302660

The calculations for anyone game enough to risk brain damage.

302662 http://supermotojunkie.com/showthread.php?138280-Electric-supermoto

Remember that guy who was building an electric bike in Wellington.

Well I came across this one, 137kg with rider and by the looks of it an electric bike could be very competitive on a Kart track.

Electric bike kicks arse:- https://www.youtube.com/watch?v=xC9KYF-SJkU

Electric bike dyno run:- https://www.youtube.com/watch?v=bwoGXQDzB-s

[el chupacabra]

Is there any chance anyone here could give more info about the swissauto 500? I am curious to know if the cylinders fired in pairs etc. Any pictures would be sweet.

I have read through most of this and this particular engine interests me very much so, I cant understand why it wasn't done more, the flying web crank.

[husaberg]

Is there any chance anyone here could give more info about the swissauto 500? I am curious to know if the cylinders fired in pairs etc. Any pictures would be sweet.

I have read through most of this and this particular engine interests me very much so, I cant understand why it wasn't done more, the flying web crank.

I have a lot of stuff in my album http://www.kiwibiker.co.nz/forums/album.php?albumid=4833
Which it seems not everyone can see............
but I fished earlier hoping someone would pipe up.

I am pretty sure the original one fired together in each pair as two singles but I am not sure the later solos were definitely different....WOB, Frits?

I found some stuff today on pitlane that suggested it was a squashed boxer? but I am not sure how well it was translated by google
Maybe someone could translate
http://www.pit-lane.biz/t1461p40-technique-moteurs-motogp

[Frits Overmars]

If the back squats down under power it puts more weight and therefor traction on the back wheel and unloads the front. Wrong. Squat will lower the Center of Gravity, which reduces the load transfer during acceleration and deceleration (not the weight transfer; the masses of bike & rider don't shift in a horizontal way under acceleration and deceleration, unless you're riding with a half-empty fuel tank without slosh restraining).
Summary: the more squat you have, the less the rear wheel will be loaded and the less the front wheel will be unloaded under acceleration.


Watch MotoGP today and on virtually every corner exit the front tyre is just off the deck, thus they have just enough weight transfer (and auto Hp control) to give the absolute maximum rear grip availableLet me rephrase that for you Wob: the antiwheeliecontrol gives them just enough power to make the front wheel float - any more power and the bike will back-flip.
There is no shortage of rear wheel grip; they just can't use it.
The acceleration could be a lot fiercer if the CoG was lower or farther forward, but that would give problems with insufficient roll velocity or with front-flips.
It's all about finding the right compromise (as Ducati seems to be discovering now after years of struggling).

[SwePatrick]

Study this clip:
https://www.facebook.com/video.php?v=10151671415074475

It is my MT5 in dyno, here you can se how it compresses the fork when the HUGE!!!! torque is torquing ;)
As someone stated earlier, everything has it´s 'negative force'(dunno the word) against the force applied to the item.
In this case, compressing the fork lets the spring compress the wheel again´st the ground.
and the force to lift the moped in the rear is also pressing the rear wheel again´st the ground.
Making the chassi less prone to raise the frontwheel in acceleration.

rgds

[F5 Dave]

Meh the spring s on those are so soft I cut 6 coils off to get in the right ballpark. And damping? Only when it rains.

[wobbly]

The SA500 engine was used in the Pulse and I rebuilt the one that Bill has when it first arrived in NZ..
Its cylinders did fire in pairs, and were very cleverly triggered by a N and S pole magnet embedded in a flywheel with a single trigger.
The pistons were A Kit Honda, with the domes machined off, leaving only the squish band radiused up from the timing edge.
Made them very light, but wow I thought the dome would sink for sure - never did.
Having a flying web only supported by a pin on each side of a flat plate in essence made for hideous stress levels and the only way the cranks would live
for any reasonable time was having them made in unbelievably expensive materials and processes.
They cost in the region of E20,000 each I believe, did 1500Km and then in the bin.

The reeds were very small in area and the carbs ( mag Keihins at E120,000 for 2 pairs ) were equivalent to a 35mm area, so the design was biased toward good acceleration, but it still made
close to 180 Hp at the sprocket.
The cylinders were very close in design to an A kit Honda, the big difference being the B port hook was a smooth radius, pointing to 1/3 across the piston to bore centre ( and of course SA on the side )
Again, all designed for mid power - I have some sitting on my bench if you want some pics , but nothing to see of interest really.

I have got access to one of the Team Roberts built, Mike Sinclair designed frames from the Pulse project and its an amazing piece of alloy artwork.

[wobbly]

Well explained as usual Frits.
The main point of my rant about anti squat really was that it acts just like the old idea of using the front brake torque reaction to try and stop the forks
from compressing,with push rods and lever arms etc.
The idea is a great one, to stop the front dropping, but in execution the result is in effect the same as ramping the spring rate thru the roof - thats why no one uses it
( nor the idea of controlling front damping with brake pressure )..
Using this effect the forks wont react as " suspension " when the brakes are on, so any surface irregularity makes the front loose all wheel control.
Anti squat % in concert with the proper ride height/spring rate for the correct static rider squat is a great tool, but thinking that seeing the rear rise a heap
under acceleration is a short sighted interpretation of a "good thing".

[Drew]

Wrong. Squat will lower the Center of Gravity, which reduces the load transfer during acceleration and deceleration (not the weight transfer; the masses of bike & rider don't shift in a horizontal way under acceleration and deceleration, unless you're riding with a half-empty fuel tank without slosh restraining).
Summary: the more squat you have, the less the rear wheel will be loaded and the less the front wheel will be unloaded under acceleration.

The more squat, the less weight transfer. Kind of. But most of the time not in real life. The shock will compress until the spring is tight enough that the front comes up anyway, most of the time. On real bikes anyway, possibly not with buckets because of their low power. But in the terms of this thread, 25-35 ponies will lift the front wheel to near on zero load in the first three gears.

[2T Institute]

Well explained as usual Frits.
The main point of my rant about anti squat really was that it acts just like the old idea of using the front brake torque reaction to try and stop the forks
from compressing,with push rods and lever arms etc.
The idea is a great one, to stop the front dropping, but in execution the result is in effect the same as ramping the spring rate thru the roof - thats why no one uses it
( nor the idea of controlling front damping with brake pressure )..
Using this effect the forks wont react as " suspension " when the brakes are on, so any surface irregularity makes the front loose all wheel control.


Garelli's had that as well as a few other 80cc GP bikes, then there was the famous Preston Petty anti dive on mx-er forks. The only person I ever heard of that rode a bike with one fitted said the most difficult thing was the weird feeling of front forks rising when the brakes were applied. No wonder they went as fast as they appeared

[TZ350]

If the back squats down under power it puts more weight and therefor traction on the back wheel and un loads the front.

Wrong. Squat will lower the Center of Gravity, which reduces the load transfer during acceleration and deceleration (not the weight transfer; the masses of bike & rider don't shift in a horizontal way under acceleration and deceleration, unless you're riding with a half-empty fuel tank without slosh restraining).

Summary: the more squat you have, the less the rear wheel will be loaded and the less the front wheel will be unloaded under acceleration.

I just knew this was going to give me a headache.

[husaberg]

The SA500 engine was used in the Pulse and I rebuilt the one that Bill has when it first arrived in NZ..
Its cylinders did fire in pairs, and were very cleverly triggered by a N and S pole magnet embedded in a flywheel with a single trigger.
The pistons were A Kit Honda, with the domes machined off, leaving only the squish band radiused up from the timing edge.
Made them very light, but wow I thought the dome would sink for sure - never did.
Having a flying web only supported by a pin on each side of a flat plate in essence made for hideous stress levels and the only way the cranks would live
for any reasonable time was having them made in unbelievably expensive materials and processes.
They cost in the region of E20,000 each I believe, did 1500Km and then in the bin.

The reeds were very small in area and the carbs ( mag Keihins at E120,000 for 2 pairs ) were equivalent to a 35mm area, so the design was biased toward good acceleration, but it still made
close to 180 Hp at the sprocket.
The cylinders were very close in design to an A kit Honda, the big difference being the B port hook was a smooth radius, pointing to 1/3 across the piston to bore centre ( and of course SA on the side )
Again, all designed for mid power - I have some sitting on my bench if you want some pics , but nothing to see of interest really.

I have got access to one of the Team Roberts built, Mike Sinclair designed frames from the Pulse project and its an amazing piece of alloy artwork.

Thanks Wob so the later ones did not have the intake shielding like this? (post later)
302850

Also were the later ones still hirth coupling? (post pic later)
302845302846
302848302847

[Drew]

I just knew this was going to give me a headache.

It gets more complicated when ya start fiddling, and what everyone says is the right direction takes you into worse handling. Then, to really fuck with ya the lap times don't reflect what the rider is telling you. Oh the fucken joys of it all.

Lets step back from the complicated for a moment and start at the beginning.

First step. Establish a clear vocabulary with your rider. Identify the four parts of a turn, braking, tip in, tranition from brakes to gas (apex), corner exit are what I call them.

Loads of people call difderent stuff by different names, it's frustrating and counterproductive at times. Be clear with one and other.

Riders are pricks. If thet start questioning what and why you're doing some thing, chuck the toolbox at their head and let them figure it out themaelves. Mind, since you're just learning about it that might be a touch drastic.

KSS have a booklet free for download. It's for beginners but explains a lot. Everyone should have it handy.

[wobbly]

The late model SA500 had shields but a cutaway slot allowing A/F to be "flung" upwards from crank rotation.
The latest TM125 kart engines have exactly the same idea.
I will have one apart soon so will pic this, as according to my info from Maxter its worth at least a Hp in 40ish.
Yes the cranks were Hirth assembled.
Funny how the SA case has a striking resemblance to this model.

[richban]

Pick an advance number ( I usually use 28* that is the initial straight line on the ignition graph from 2000 up to say 7000 rpm ).
Convert this to mm down the bore, and use a DTI to set the piston exactly at this number.
Then arrange a scribe or white pen line on the rotor and stator that is easy to see with your strobe.
Fire it up and strobe the lines mechanically set at 28* holding the rpm steady between 2000 and 7000.
Adding more base timing will retard the firing line and visa versa.
This will ensure you are mechanically and electrically on the money in the Ignitech.
I have found that the only strobe that is dead accurate is the old, super el cheapo ones, that are in line with the plug leads.
Used to be $12.00 at Repco.

Well I think I did it correctly. 180 divide by 54.5 = 3.302. So i figured coz I like round numbers I would do 10mm down from TDC with the dti. So 33 degrees.

So made a map that was 33 deg from 2 - 7. Fired up and looking good and quite a way out. Only problem was I just could not get it to move much at all. I tried putting in a negative value but it would not let me. This is with the P2 Race. Am I putting it in on the wrong screen. Advance screen that is. Help!

[Yow Ling]

Shields and a cut away slot, a bit like this?
302867

Things are moving along, ports only need a couple of degrees onthe exhaust , and 1 degree on the a and b ports so getting a bit closer
302868

[Yow Ling]

Well I think I did it correctly. 180 divide by 54.5 = 3.302. So i figured coz I like round numbers I would do 10mm down from TDC with the dti. So 33 degrees.

So made a map that was 33 deg from 2 - 7. Fired up and looking good and quite a way out. Only problem was I just could not get it to move much at all. I tried putting in a negative value but it would not let me. This is with the P2 Race. Am I putting it in on the wrong screen. Advance screen that is. Help!

33 degrees is 5.45mm with a 105mm rod so your maths is a bit off because near tdc you get lots of degrees and fuck all mm, its not a simple 180/54 job

here is a calculator http://www.dansmc.com/mc_software2.htm

[richban]

33 degrees is 5.45mm with a 105mm rod so your maths is a bit off because near tdc you get lots of degrees and fuck all mm, its not a simple 180/54 job

here is a calculator http://www.dansmc.com/mc_software2.htm

Opps............. Cheers ears.

[Bert]

Opps............. Cheers ears.

Double opps. Sorry Richard.

So use to using my buzzetti tool and the maths over the phone failed me...

[richban]

Double opps. Sorry Richard.

So use to using my buzzetti tool and the maths over the phone failed me...

All good done me some learning. Bugger though means I have to pull the head off again.

[TZ350]

302883

Chambers, Fastfred and I got to play with a 50 on the dyno tonight.

302880

Chocolate Fish if you can match the pipes to their dyno curves.

302879

All this suspension talk is exciting now that I am making progress on the new bike.

302881302882302884

All adjustable suspension and blinged out with freshly painted wheels and even hollow weight saving sprocket bolts.

[TZ350]

YSS have a booklet free for download. It's for beginners but explains a lot. Everyone should have it handy.

Great, found it (I think):- http://www.yssusa.com/suspension_problems.html Thanks.

[Bert]

302883
Chambers and I got to play with a 50 on the dyno tonight.
302880
Chocolate Fish if you can match the pipes to their dyno....
.....s.

I'll try for a chocolate fish.

Blue run second from top
Red run third from top
Dark blue run - bottom
Purple run - third from top
Green run - top

But chances are I'm not catching...

[dark art]

302883

Chambers and I got to play with a 50 on the dyno tonight.

302880

Chocolate Fish if you can match the pipes to their dyno curves.



colors in order on the graph and 1st pipe top.

blue - 5º
red - 1º
dark blue - 3º
purple - 6º
green - 4º

2º pipe the curve is not there.

[Drew]

Great, found it (I think):- http://www.yssusa.com/suspension_problems.html Thanks.

That looks quite good. Dunno where I got YSS from, Robert Taylor has also done one for racers. KSS is what I meant, but full credit for finding that.

[wobbly]

So you optimised the fuelling and the timing for each pipe ?
Would seem impossible for the same ignition to work on a pipe that peaks at 10500 and another that peaks at 13500, and I bet all the stingers were different
so would have wildly varying egts as well.
But what do I know.

[wobbly]

Here is the sideways slot on a TM125KZ10B

[FastFred]

So you optimized the fuelling and the timing for each pipe ?

Yeer, hours spent changing jets and adjusting the ignition ....... nar, it was a few bears and a bit of after work fun... :drinknsin

What we can say for sure is:- the best sounding one was the second to worst performing pipe.

[husaberg]

Here is the sideways slot on a TM125KZ10B

If you don't mind me asking do you have a pic of the intake tunnel, its a front intake isn't it?(I'm not a kart guy)
they run backwards though i guess?

[wobbly]

Here is the front tunnel.
The crank spins forward as normal, so the ramps over the crank shield the intake flow from the turbulent boundary around the wheels.
The rear slot lets "flow" from around the crank up under the piston.
Mr Thiel tried the shields on the Aprilia and found some power as well, but dont know if the sideways slot was tested at the time.

[Frits Overmars]

The crank spins forward as normal, so the ramps over the crank shield the intake flow from the turbulent boundary around the wheels.....Mr Thiel tried the shields on the Aprilia and found some power as well, but dont know if the sideways slot was tested at the time.At the time Jan was thinking about the RSA inlet disk position and he wanted to find out whether the direction of crankshaft rotation had much influence on the inlet flow. So he put a standard kart engine on the test bench, measured the power, started it in reverse and measured the power again. 'Reverse' , meaning the crank rotating backward, gave one extra horse.
I discussed this with Roland Holzner of Modena Engines the other day and he told me that they'd already performed the same test at Rotax. Roland said that the negative effect wasn't so much due the counter-flow induced by the crank webs, but mainly due to the fact that the fat end of the con rod was directly in front of the reed case at the moment of initial inlet flow.

[husaberg]

I mused a while back about a combo of the Swiss Auto V4 mixed with JBB.
302897302898302899

I can't come to grips though how much the flapping around of the unsupported crank might cost in hp.
but I tried to get my head around if the outer piston ring seal might offer support or more likely just make it bind.
I even tried to picture an outer bearing outside the crankwheel.........
I just love the way the swissauto is so compact in width.
I also know Honda did at least design if not build something very similar a little earlier.

I found this engine a flying web rotax based v twin.

[husaberg]

Pics that would not fit of the home spun flying web

[TZ350]

Here's some help on searching in these forums.

Top right hand corner of the screen, click 'advanced search'
Click the blue box 'search single content type' at the top.
Scroll down and select the forum area to buckets which is right near the bottom of the list.
Scroll down and select the dot next to 'posts' in the criteria called 'show result as'.

304439304438304437

THREAD IMAGES
Another handy tip is under thread tools (near the top of this page) click view thread images. Very! Helpful on the ESE thread

page 1010 links list.

Suspension tuning .... well I do not have a clue but need to learn so here is a collection of recent posts about Squat and Anti Squat. I have posted all the comments and have no idea about what is right. Interesting enough though, so worth picking through it for yourself.

NSR250 suspension tuning:- http://nsr-world.com/tuning/250-tuning/suspension/



http://i62.tinypic.com/r6w8cg.jpgktm all but ready to fire upThat Sir, is a seriously serious looking bike, I had better get a move on, Team ESE's 2T's are being left behind.



http://youtu.be/sMKc5R8ZEeg?list=UUg1Ze1muy87n3mkhOHMXVSg

Watch closely how the frame / suspension responds to being loaded up... No squatting in the backend under acceleration. Well done Scott, those frame modifications have made it even better.
:2thumbsup


Some squat is accepted as an absolute must on proper bikes. If it is tuned out with a steep swingarm such as that bike, the drive force is fighting the suspension and you sacrifice traction.

Might be alright with twenty or thirty ponies to ride (but could be better), but pump a hundred and ninty through the tread and things get...interesting on corner exit.


Drew is right about having so much anti squat the bike rises and pulls against the tiedowns on the dyno. All this is good for is stopping dyno wheelspin. I made that mistake with the Frepin TZ400.
As it was setup it had too much anti squat, via the swingarm angle.

Around the sweeper at PI it would step out the rear when Discombe powered it into a 2 wheel slide. I dropped the rear 10mm ,as much as I could on the Ohlins mono shock,and it would then almost take full power in a controlled slide
all the way onto the front straight.

Denis is about to shorten the shock so it can be dropped a little more, so then it can be set up each side of pro or anti squat in testing.


The big angle can be fine, so long as the front sprocket is high and the line between axle, swinging arm pivot, and front sprocket centre are close to in line with the rider on it.

But the geometry of the bike is effected more with big compression, ie when the bike is leaned over and there's large g's acting on the suspension. This could be used to an advantage I suppose. By crikey there'd be a shit ton of testing and data logging to paw through. In real terms I expect GP is the only environment that would or has happened.


we are talking about the bike in the video not tz400 etc , the bike is built for bucket tracks didifferentrom standard track , i don't got looking for shit on the net and post it. i go for what a have learn't building frames and racing and there is always more to learn , i look at it as the rear end rise's it pushes the rear into the track which keeps the front on the ground for better turning( not running wide). as g forces come into effect and different weights of the bike it will change ( heavy bikes more lightly to swat but a well set bike like motor gp bike look to sit neutral . i don't have the time to sit her blabbing on as i have bike to build and learn more . think about what i have put? , i raced guys bikes over the years that say there bike it sliding out , doing all sort of crap , i ride it , go 5 seconds a lap faster and think it go's like a dream . best to get out on the track and do what suits you to go fast


As is the case with every single aspect of suspension and geometry of a motorcycle. They cannot be built to do everything to it's potential.


bang on if you can win with what your on its working


" as the rear end rise's it pushes the rear into the track whichs keeps the front on the ground for better turning".

Thats dead correct except its back to front thinking in my opinion. If you have an issue with running wide on exit then you need to look at gaining some front end turn - drop the forks thru. Gaining front grip by killing the rear end with anti squat does "work " but in the example I gave with the Frepin, it was loosing rear grip under power when tipped over hard.

So I didnt try to fix that by reducing the front grip, I dialled in some more natural rear grip by reducing the anti squat % - dropping the rear ride height. This works just as well around the sweeper at Mt Welly where even at those slow speeds the suspension is heavily compressed.

No Mates bike initially used to step the back out when leaned over going as hard as he could around the sweeper.
Dropping the back gained some rear grip by reducing the anti squat.

It then started to run wide on turn in,so rather than reduce the good rear grip we had just gained he dropped the forks thu to steepen up the front. Now it steered, and had rear edge grip - seemed to work OK, he won on Mt Welly 3 years in a row.

Same idea with Discombs TZ350 around Hampton when he won the Sheene last year. It was pattering and loosing front grip when hard over exiting the sweeper under power - that bike has near on no anti squat at all, so all we could do was reduce the squat by winding in a heap of preload and a couple of compression clicks.

This stopped the rear from squatting so much and unloading the front - then it steered at full noise onto the front straight - seemed to work, he was 3 secs a lap faster than anyone in his class.

Its always best to try and gain grip to balance out a lack at one end, reducing the grip at the opposite end can and does work - if that all that can be done to fix pig handling.


Niges real problem is the spring at the rear is too soft for his fat arse. I spent a bunch of time watching at the last GP as my bike had welded it's clutch. And you could see it going full stroke and stepping dread fully at Tokaroa which is a severe track. He hadn't noticed but was still frothing at the mouth post race. Ahh we're all getting too old. To be fast again.


I actually thought it was an interesting thing to discuss.
Given late model RS125s and TZ125s tend to show this as well. The GPR frames feel great on track.

Wobs post above makes good sense, I can imagine that the more mass (weight) and more power - loads up the front with too much anti squat and if front end is not setup to deal with it then it will all go pear shaped.


It's not the front that it goes pear shaped at. The rear lets go in a hell of a hurry, because the suspension isn't working due to the torque fighting it. So there's no give and when it hits a bump the wheel leaves the ground.

The distance between the two sprockets is at it's greatest when the swingarm pivot and sprocket centers are all in a straight line. When you put the rear sprocket lower than that straight line and apply the gas, the torque is trying to pull that sprocket forward by shortening the distance more as the swingarm further extends.

Loading a tyre more is the goal, bump compliance is the unfortunate requirement for suspension.


What many forget is that there is a finite mass of bike and rider. Using antisquat to transfer some of that finite amount to the front - MUST by definition reduce the rear. Less or neutral anti squat by dropping the ride height and the swingarm angle ,allows more weight transfer to the rear - increasing grip at that end.

The anti squat rising force is an internal frame vector, the actual result of the frame rising ( thus the rear wheel pushing down ) is weight transfer off the rear and onto the front - counter intuitive I know, but increased FRONT grip is what actually happens in the end.

Add to that the dramatic increase in effective rear bump rate under power, and anti squat although intellectually an obviously useful tool, suddenly becomes a very sharp double edged sword.


One thing to be careful of TeeZee is that the rear wheel will try to climb up the dyno roller under power - giving the illusion of a big anti squat %. To get an idea of the squat rate you have to be aware of the wheel position.


Thanks for the tip.

302649

I can see the possibility of a headache coming on, while trying to get to grips with understanding suspension tuning.


Get the spring rate right, set the sag with rider, and static the swingarm should be pointing close to the middle of the front sprocket or slightly above.

Adjust the tendency to run wide or tip too fast with fork height. This is the start point. From it you are in the crazy land of suspension damping, and the endless trade offs you are forced to deal with.

You're pissing in the wind with the wrong springs.

Have fun.


squat with ant squat working together is what gives traction , remove ant squat out of it and let it squat under power will i think go from unloaded to overload as it bottoms out , i bit of both is a good controlable ride


Could you explain where this increased grip on the front wheel is coming from?

Anti squat causes an increase i frame height (or in reality pitches the bike forward) when accelerating. Under steady acceleration the only affect this will have is to raise the COG height of the bike+rider, which will increase normal load on the rear wheel (due to pitching moment from acceleration), and take it off the front - more rear grip, less front.

Under a transient acceleration (acceleration of acceleration) the chassis will be accelerated upwards, and a reaction force will be seen at the rear wheel (D'Alembert's principle). This reaction force stops when the acceleration becomes steady or begins decreasing. This is more often a smoother affair and is unlikely to happen during a corner. So - More rear grip followed by maybe less rear grip if you decide to shut the throttle.

I am struggling to see in all this a reason for the front wheel to see increased grip. What am I missing?

EDIT: Is it inertial moments causing the bike to pitch about some point ahead of the COG, causing a larger reaction force at front wheel due to a shorter moment arm? That would mean that the motion increases load on both wheels (but more so at the front) and the reverse motion (springing back to neutral position) unloads both wheels. (Not sure I explained that too well)


With the rear shock unable to compress, as soon as the tyre reaches the top of a bump YOU LOSE TRACTION. Not gain it.

Ps. Weight distribution is where tye extra front grip comes from. But it is important to realise that this is a different part of the turn. Corner entry is where raising the rear gives more front grip, the trade off being less exit grip at the rear.


The spring is constantly pushing the wheel onto the road. Corectly sprung you should be able to tune with damping for nearly any track.

Antisquat is getting to the uppermost technical side of suspension tuning. 99% of riders need never worry about it unless they get a bike that's been set up too high to begin with.


Anti squat doesn't remove the ability for the rear shock to compress though , unless you were to run a shit tonne of it and topped the shock out. The spring can still compress just the same, it is just sitting higher than it was.
Bumps aren't the only transient concern on a motorcycle. In fact they are a pretty small factor compared to inertial loads when you are riding around on billiard tables i.e. a racetrack.


Wrong - anti squat force is obtained by the chain trying to pull the rear wheel forward, or put another way - to shorten the swingarm. When the swingarm is at an acute downward angle, as the chain pulls harder the resultant anti squat reaction forces the rear of the bike upward.

By the obvious physics of action and equal re action, then rear wheel is being pushed downward at the same time with the same force value. Thus it is this reaction force ( an internal frame force ) that prevents a bump or track ripple from compressing the rear shock, via the rear wheel rising in relation to the seat height.

So although the shock/spring combination may actually physically able to compress, it cant due to the high internal frame force trying to lengthen the shock.

When in this powered on state, a bump will have to lift the rear of the bike AND the riders bum mass as well, this is not called suspension, its called a jolt in the arse closely followed by an instantaneous slide, closely followed probably by a highside - they hurt.

To prove any theory, go to the nth degree. With a lot of pro squat dialled in via front sprocket height, and or swingarm angle - under power on conditions ultimately ALL the bike/rider mass will be transferred to the rear tyre.
ie a wheelstand.

Watch MotoGP today and on virtually every corner exit the front tyre is just off the deck, thus they have just enough weight transfer ( and auto Hp control ) to give the absolute
maximum rear grip available - the front tyre is off the ground, directional control is then only via counter-steering and rider weight.


302661

Squat Anti Squat


302660

The calculations for anyone game enough to risk brain damage.

302662 http://supermotojunkie.com/showthread.php?138280-Electric-supermoto

Remember that guy who was building an electric bike in Wellington.

Well I came across this one, 137kg with rider and by the looks of it an electric bike could be very competitive on a Kart track.

Electric bike kicks arse:- https://www.youtube.com/watch?v=xC9KYF-SJkU

Electric bike dyno run:- https://www.youtube.com/watch?v=bwoGXQDzB-s



So as I understand it so far (and probably incorrectly):- If the back squats down under power it puts more weight and therefor traction on the back wheel and un loads the front.
Wrong. Squat will lower the Center of Gravity, which reduces the load transfer during acceleration and deceleration (not the weight transfer; the masses of bike & rider don't shift in a horizontal way under acceleration and deceleration, unless you're riding with a half-empty fuel tank without slosh restraining).
Summary: the more squat you have, the less the rear wheel will be loaded and the less the front wheel will be unloaded under acceleration.

Let me rephrase that for you Wob: the antiwheeliecontrol gives them just enough power to make the front wheel float - any more power and the bike will back-flip.
There is no shortage of rear wheel grip; they just can't use it.
The acceleration could be a lot fiercer if the CoG was lower or farther forward, but that would give problems with insufficient roll velocity or with front-flips.
It's all about finding the right compromise (as Ducati seems to be discovering now after years of struggling).


I just knew this was going to give me a headache.


Well explained as usual Frits.

The main point of my rant about anti squat really was that it acts just like the old idea of using the front brake torque reaction to try and stop the forks from compressing,with push rods and lever arms etc.

The idea is a great one, to stop the front dropping, but in execution the result is in effect the same as ramping the spring rate thru the roof - thats why no one uses it ( nor the idea of controlling front damping with brake pressure )..
Using this effect the forks wont react as " suspension " when the brakes are on, so any surface irregularity makes the front loose all wheel control.

Anti squat % in concert with the proper ride height/spring rate for the correct static rider squat is a great tool, but thinking that seeing the rear rise a heap under acceleration is a short sighted interpretation of a "good thing".


The more squat, the less weight transfer. Kind of. But most of the time not in real life. The shock will compress until the spring is tight enough that the front comes up anyway, most of the time. On real bikes anyway, possibly not with buckets because of their low power. But in the terms of this thread, 25-35 ponies will lift the front wheel to near on zero load in the first three gears.


Garelli's had that as well as a few other 80cc GP bikes, then there was the famous Preston Petty anti dive on mx-er forks. The only person I ever heard of that rode a bike with one fitted said the most difficult thing was the weird feeling of front forks rising when the brakes were applied. No wonder they went as fast as they appeared


It gets more complicated when ya start fiddling, and what everyone says is the right direction takes you into worse handling. Then, to really fuck with ya the lap times don't reflect what the rider is telling you. Oh the fucken joys of it all.

Lets step back from the complicated for a moment and start at the beginning.

First step. Establish a clear vocabulary with your rider. Identify the four parts of a turn, braking, tip in, tranition from brakes to gas (apex), corner exit are what I call them.

Loads of people call difderent stuff by different names, it's frustrating and counterproductive at times. Be clear with one and other.

Riders are pricks. If thet start questioning what and why you're doing some thing, chuck the toolbox at their head and let them figure it out themaelves. Mind, since you're just learning about it that might be a touch drastic.

KSS have a booklet free for download. It's for beginners but explains a lot. Everyone should have it handy.


Great, found it (I think):- http://www.yssusa.com/suspension_problems.html Thanks.


That looks quite good. Dunno where I got YSS from, Robert Taylor has also done one for racers. KSS is what I meant, but full credit for finding that.


NSR250 Engine Tuning:- http://nsr-world.com/tuning/250-tuning/engine/

Ed Tuck racing (NSR250):- http://edetuckracing.blogspot.co.nz/p/fitting-rm125-pistons.html


http://www.twostrokeracelab.com/


http://www.2strokers.com/index.php?topic=184.0

[senso]

Here is the front tunnel.
The crank spins forward as normal, so the ramps over the crank shield the intake flow from the turbulent boundary around the wheels.
The rear slot lets "flow" from around the crank up under the piston.
Mr Thiel tried the shields on the Aprilia and found some power as well, but dont know if the sideways slot was tested at the time.

One quick question Wobbly, does that TM kart engine have a balance shaft or not, I suppose it does, but I cant find any information about that.

Best regards.

[Haufen]

I am trying to sum this up in my head

What we've learned so far:
on a horizontal case reed, induction in crankshaft direction is favourable vs inducting against crankshaft rotation. On the latter, having a rear slot is beneficial, and shielding the crank webs is probably beneficial, too.

What if induction is in crank direction? Is shielding beneficial there, too? Would a rear slot be a good idea? Or maybe a front slot?
And what if the reed is aligned vertically? Which setup would you say is best, depending on crank rotation?
And given you could choose the best (reed) setup there is, which one would it be? e.g. horizontal reed, induction in crank rotation direction? shielding? slot?

[wobbly]

I think we can make a deduction from what has actually been tested.
The Maxter engines under Roland have been made identically with vertical and horizontal reeds, and I assume now that due to the rod position
they have "gone back " to the horizontal reed as the best compromise.
Jans rear rotary valve engine worked very similar to what would be regarded as a normal rear case reed, but I have never seen a crosswise slot in an RSA or
in the ramps of any of the rear reed type engines - plenty of examples of ramps with the longitudinal rod slots though.
Probably not a good idea in that IF there is any actual flow upward away from the crank thru a crosswise slot, it will be directed into the path of the incoming
tunnel flow from the reed tips.
But hey, more power is gained with the new generation of kart engines with the reeds pointing at an upward angle toward the piston, so having upward flow from the
crank as well might end up being an advantage - anyone got a spare RS125 I can try it on.
They dont like a bigger case vol though - been there with reed spacers, so cutting a slot in the case would have to be done adding vol somewhere else, for a true
back to back - but its not allowed under the rules.
Maybe I can cut mill the KZ10 reed mounting face to reduce the vol, now there is a thought for the day - off to the bench now to have a look.
If that doesnt work I can respace the reed with a plate - thats allowed as the " intake " is open.
No kart engines have balance shafts - not sure if thats by design or in the rules, they dont vibrate at all anyway especially with heavy cranks with added Mallory.

[richban]

Well after checking re checking and checking again. Looks like the engine was running 2 degrees advanced. So 16 degrees at peak power with no sign of det. That Avgas sure seams to need lighting up early. Now fascinated with this I am sorting the det gauge and will very interested to find out what the engine really wants to get her humming.

[F5 Dave]

strange shit can happen. I'd set the new engine up last night with a flat 15 & then introduced the curve of the old one (which the old one had liked, itself a mod of the RZ400 one posted a while back) adjusted a bit for the change in revs but still flat 15 at peak

but peak went down & spread went down. Flat 15 brought it back. More testing required.

While I was a it I was running a 310MJ, 300 went better, 290 was better still, better spread but knock gauge flashing and all gears a big fall off in upper gears. 320 was just as good as 290 and no det, no fall off. I might have to build a jet flow tester.

[wobbly]

So Rich did you add or reduce the base timing to get the lines aligned?
But yes, Avgas has alot of additives to stop freezing at 35,000 ft etc that slow the burn speed, but even LL100 is a shit
load better than even our souped up 98 Pump with ethanol.

[richban]

So Rich did you add or reduce the base timing to get the lines aligned?
But yes, Avgas has alot of additives to stop freezing at 35,000 ft etc that slow the burn speed, but even LL100 is a shit
load better than even our souped up 98 Pump with ethanol.

Reduced the the base to get it lined up. Don't tell me I have round the wrong way again. I am dyslexic so easy done. Also I live next to wellington airport straight from the pump is good.

[wobbly]

Reducing the base timing advances the firing point, so you were retarded ( probably in more ways than 1 ) by 2 degrees.
ie if the curve said 15 you were at 13.
So mate, if you thought it was fast before, then hang on.
Makes complete sense re the high temps you were seeing without any piston distress.

[husaberg]

Wobs post earlier made me think of this engine, I had it in with some Aprilia pics
Anyone know what is it?
likely off pitlane, I forgot to include the link code....

[husaberg]

RSA and RSW

[richban]

Reducing the base timing advances the firing point, so you were retarded ( probably in more ways than 1 ) by 2 degrees.
ie if the curve said 15 you were at 13.
So mate, if you thought it was fast before, then hang on.
Makes complete sense re the high temps you were seeing without any piston distress.

Well sheeeit.

She will be pumping 90 before the cemetery circuit. Really looking forward to the Tri Series. I will be hunting down some A747 for the Street race. Smells like fast.

[Frits Overmars]

No kart engines have balance shafts.None of the shift-engines, as far as I know. But all of the non-shift engines, as far as I know. And those have mechanical coolant pumps too, and most if not all of them have electric starter motors.
What amazes me most is that Maxter for example builds 125 cc shift-engines without balance shaft and without pump, but also 125 cc non-shift engines with balance shaft and with pump. So I guess it's not a design issue; it must be in the regulations somewhere.

[Frits Overmars]

Wobs post earlier made me think of this engine, I had it in with some Aprilia pics
Anyone know what is it?Your unknown engine is an ADM (built by Charlie AufDerMauer), a Swiss clone of the Aprilia RSA125 engine, in Honda RS125 frame.
In your pictures a Honda RS250 cylinder was fitted. Here are some more pics of that engine, this time with a proper ADM cylinder.

[senso]

It has some big cooling fins in the crankcases, the metal piece that goes through the pick-up looks strange to me.

[wobbly]

The metal trigger plate is a copy of the Honda, it uses a long and short " lobe " for some reason to do with the PGM system ECU.
But this is easy to get to fire with an Ignitech.

[richban]

The metal trigger plate is a copy of the Honda, it uses a long and short " lobe " for some reason to do with the PGM system ECU.
But this is easy to get to fire with an Ignitech.

With the ignitech can you put in a minus value in the base advance setting?

[wobbly]

Nope, this in effect means the trigger is too close to TDC, but if you need more advance to get the timing lines spot on, then add some timing in the channel
trim boxes down the bottom of the ignition curve page.
You can use these to check each cylinders timing when under load on the dyno, means you can correct for crank wind up and also a crank that hasnt been assembled in phase correctly.
Doing this means you know for sure both cylinders are actually firing when the curve says it should.

[lodgernz]

So there you have it - the A Kit pipe is shit in comparison to that layout.
You have a 2 stage header with the optimum angles of 3.5 and 5.5 * ( even better than Aprilias Tubo designs that to my knowledge never had a 2 stage )
with a 3 stage diffuser,the steepest in the middle with approx equal angled 1st and 3rd stages - all good.
The tapered belly section can be tapered either way, depending upon the engines response to the diffuser action and how much overev it is capable of ( or needed ) via a steep rear cone.
The only element that I have found to work better is the relationships in the header.
In your design the end of the first header is at around 75% = 200/268,but as in the empirical design guides for the whole pipe of 33% header 66% diffuser, the same applies to the header lengths.
End the first 3.5* cone at around 66%, so you would then have two equal headers of 91.5mm ie 60+25+91.5 = 176.5/268 = 66%, thus the second header at 5.5* is 91.5/268 = 34%.

Wobbly, I'm still reeling from your above statement about header angles. Are 3.5* and 5.5* really optimum for headers?
That's just so much steeper than anything I've ever read anywhere, and makes the small end of the first diffuser so big that there isn't much more diameter left for the diffusers before reaching the optimum belly diam. Am I missing something? (Apart from brainpower, youth, good looks, hair, etc)

[wobbly]

Anything you have read is based in early 20th century experience and has no relevance to anything that can be achieved nowdays.
The angles quoted are assumed to be used on a high performance /race engine, not a Frances Barnett or some such shitter.
The first pipes started showing up with two stage headers with steeper angles way back in the early days of the Rotax 250 and were designed
by someone with the initials of VSK ( sounds Dutch as hell - Frits probably knows him ) I have been told, as these designs were published year on year as bigger numbers but always with VSK in front.
Those angles also assume that the engine can use effectively steep diffuser angles as well, this means that the transfers and ducts are reasonably well designed.
When you connect shit transfers to a fat pipe with steep angles, you get way more depression around BDC than the transfer streams can resist.
They loose directional coherence - they abandon the loop ,do a U turn and disappear out the header - overscavenging is the term coined by Erv Kanemoto when trying to get fat pipes on a TZ750.
Apart from having no physical room on the bike he found that on his single cylinder mule, anything over around 108mm lost power.
Nowdays we can scavenge a 125 cylinder effectively with a 134mm belly,something just not possible without very good loop control within the bore.

[2T Institute]

Your unknown engine is an ADM (built by Charlie AufDerMauer), a Swiss clone of the Aprilia RSA125 engine, in Honda RS125 frame.
In your pictures a Honda RS250 cylinder was fitted. Here are some more pics of that engine, this time with a proper ADM cylinder.

It's cousin EGA 125 (disc valve conversion to ADM NF4 cases) now resides on the southern hemisphere :msn-wink:

Did that RSA copy ever race Frits?

[Kickaha]

Your unknown engine is an ADM (built by Charlie AufDerMauer)
I take it he built the ADM 500/4 sidecar motors? Did he work at Krauser when they were doing the same?

[husaberg]

I take it he built the ADM 500/4 sidecar motors? Did he work at Krauser when they were doing the same?

I think ADM did a V3 as well?

Your unknown engine is an ADM (built by Charlie AufDerMauer), a Swiss clone of the Aprilia RSA125 engine, in Honda RS125 frame.
In your pictures a Honda RS250 cylinder was fitted. Here are some more pics of that engine, this time with a proper ADM cylinder.
oh Frits thanks for solving the puzzle over what it was........
I have a feeling adm used to make cases for nf4 rs125 Hondas so they could run cassette gearboxes.......

[Kickaha]

I think ADM did a V3 as well?

They did a 500 triple with outside cylinders reversed
http://www.adm-racing.ch/index.html

[husaberg]

They did a 500 triple with outside cylinders reversed
http://www.adm-racing.ch/index.html




Here is below a couple of not so well known 3 cylinder 2 strokes.
No Honda's here. A ADM and not your normal Laverda triple either 1985
.right you are ............

[lodgernz]

Anything you have read is based in early 20th century experience and has no relevance to anything that can be achieved nowdays.
The angles quoted are assumed to be used on a high performance /race engine, not a Frances Barnett or some such shitter.
The first pipes started showing up with two stage headers with steeper angles way back in the early days of the Rotax 250 and were designed
by someone with the initials of VSK ( sounds Dutch as hell - Frits probably knows him ) I have been told, as these designs were published year on year as bigger numbers but always with VSK in front.
Those angles also assume that the engine can use effectively steep diffuser angles as well, this means that the transfers and ducts are reasonably well designed.
When you connect shit transfers to a fat pipe with steep angles, you get way more depression around BDC than the transfer streams can resist.
They loose directional coherence - they abandon the loop ,do a U turn and disappear out the header - overscavenging is the term coined by Erv Kanemoto when trying to get fat pipes on a TZ750.
Apart from having no physical room on the bike he found that on his single cylinder mule, anything over around 108mm lost power.
Nowdays we can scavenge a 125 cylinder effectively with a 134mm belly,something just not possible without very good loop control within the bore.

Thanks Wobbly, fascinating. I guess I never thought about two stage headers since none of the published RSA125 pipes used them. I'd be interested to hear Frits' thoughts on them.

[wobbly]

Well the EngMod sim is right on the money with regard to the Aprilia RSA model.
And using a 2 stage header on that pipe modified to keep the same diffuser angles - but changed to a single rear cone, it makes between
0.5 to 1.5 Hp more in varying places - never less than the baseline sim.
This I fully believe, but unless we can get our hands on a RSA to do a back to back we will never know.

[Muciek]

On Pitlane there was talk about that, pipe was someone else design (Witveen?) and Mr Thiel was designing engine around that pipe...

[Frits Overmars]

...The first pipes started showing up with two stage headers with steeper angles way back in the early days of the Rotax 250 and were designed by someone with the initials of VSK (sounds Dutch as hell - Frits probably knows him) I have been told, as these designs were published year on year as bigger numbers but always with VSK in front.I don't think VSK stems from somebody's initials; VSK has always the pre-designation of Rotax two-stroke expansion pipe drawings. This was already the case when I first got involved with Rotax engines, in 1978. I don't remember the VSK-number of the 1978 works pipe (I've got it at home in Holland somewhere) but I do remember the maximum diameter: 100 mm. Being a young smart-ass, I did some calculations of my own and according to those, that diameter should be 128 mm. Ridiculous of course, but I built it anyway. It was a missile. It took Honda all the way until 1992 before they brought out their first fat pipe (on the RS125 B-kit). And Aprilia did it in 1995 when Jan Thiel went there and carried my Rumi pipe.

[husaberg]

I don't think VSK stems from somebody's initials; VSK has always the pre-designation of Rotax two-stroke expansion pipe drawings. This was already the case when I first got involved with Rotax engines, in 1978. I don't remember the VSK-number of the 1978 works pipe (I've got it at home in Holland somewhere) but I do remember the maximum diameter: 100 mm. Being a young smart-ass, I did some calculations of my own and according to those, that diameter should be 128 mm. Ridiculous of course, but I built it anyway. It was a missile. It took Honda all the way until 1992 before they brought out their first fat pipe (on the RS125 A-kit). And Aprilia did it in 1995 when Jan Thiel went there and carried my Rumi pipe.

Frits without being to prying is the total pipe volume then more important than the actual baffle cone and diffuser angles appear to be.....

[Frits Overmars]

I would say the total pipe volume is not that important - not in itself anyway. What's important is the way exhaust gas energy is converted into suction by the diffuser, while still saving some of that energy for the positive return pulse.
It's about finding a balance. It's no use sucking a litre of fresh mixture through the cylinder into the header if only a quarter of that mixture gets pushed back.
And it's no use either if the positive return pulse not only shoves all the washed-throught mixture but also a large amount of hot spent gases back into the cylinder.

[husaberg]

I would say the total pipe volume is not that important - not in itself anyway. What's important is the way exhaust gas energy is converted into suction by the difussor, while still saving some of that energy for the positive return pulse.

Thanks I think I understand, but what I was trying clumsily to push at was that the angles are a representation of arriving at volume within the tuned length.
but yes on further thoughts the angles are I guess just as important.

I seen something just on a net troll .
I haven't had the chance to read it yet mind you.
looks to be based on Blair data........at the first glimpse
http://www.dragonfly75.com/motorbike/ECtheory.html


This bit I did notice though was about putting a parallel section in the baffle cone to broaden the power.
http://www.dragonfly75.com/motorbike/BRW.html

[Muciek]

Thanks

I seen something just on a net troll before,
I haven't had the chance to read it yet mind you.
looks to be based on Blair data........at the first glimpse
http://www.dragonfly75.com/motorbike/ECtheory.html
This bit I did notice though was about putting a parallel section in the baffle cone to broaden the power.
http://www.dragonfly75.com/motorbike/BRW.html

I have posted link to this in 2013
http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page853?p=1130623219#post1130623219

He did updated this exceel sheet few times, but dunno if this works , I tried to put there a pipe which I built for engine and I know how it works and outcome in graphs was way different....

[husaberg]

I have posted link to this in 2013
http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page853?p=1130623219#post1130623219

He did updated this exceel sheet few times, but dunno if this works , I tried to put there a pipe which I built for engine and I know how it works and outcome in graphs was way different....

Sorry I missed it........

[wobbly]

Always amazes me when people make huge jumps of blind faith when trying to explain some fantastic " new " idea they have concocted.
The 50mm piece of tube added to the tailcone will of course smear out the timed return wave, but what was completely ignored was the tuned length is now 50mm longer.
I am sure I could make an even better power curve with a "proper " pipe design that was 50mm longer - if the engines powerband shape actually needed that in the first place.

The volume of the pipe is not something that can be used as a number to shoot for, what is important as Frits said, is the end use use of the finite energy imparted down the header from the
Ex port.
The fatter the belly, and thus the steeper the diffuser, the greater energy that is used to create a depression at the port around BDC.
Thus less energy can be used to create the stuffing pulse.
This can be countered somewhat by a steeper rear cone, and this is what does happen in reality, where I have seen huge 145mm belly 250cc pipes with 30* rear cones.
This approach means the rear cone length is reduced, but the steep angle gives at least some amplitude to the event.

I was sceptical when I was told about " Mr " VSK who worked at Rotax, as I spent several years when in England working at JL pipes trying to get to talk to this mythical pipe
designer - no one knew who actually did do the designs, so I never got to meet him.
But whoever it was, the two stage header was a feature of those later pipes, and must have been dyno tested in house, for them to have been published.
Every pipe I have run thru EngMod makes better power with that design so to me its a no brainer nowdays.

[husaberg]

Always amazes me when people make huge jumps of blind faith when trying to explain some fantastic " new " idea they have concocted.
The 50mm piece of tube added to the tailcone will of course smear out the timed return wave, but what was completely ignored was the tuned length is now 50mm longer.
I am sure I could make an even better power curve with a "proper " pipe design that was 50mm longer - if the engines powerband shape actually needed that in the first place.

The volume of the pipe is not something that can be used as a number to shoot for, what is important as Frits said, is the end use use of the finite energy imparted down the header from the
Ex port.
The fatter the belly, and thus the steeper the diffuser, the greater energy that is used to create a depression at the port around BDC.
Thus less energy can be used to create the stuffing pulse.
This can be countered somewhat by a steeper rear cone, and this is what does happen in reality, where I have seen huge 145mm belly 250cc pipes with 30* rear cones.
This approach means the rear cone length is reduced, but the steep angle gives at least some amplitude to the event.

I was sceptical when I was told about " Mr " VSK who worked at Rotax, as I spent several years when in England working at JL pipes trying to get to talk to this mythical pipe
designer - no one knew who actually did do the designs, so I never got to meet him.
But whoever it was, the two stage header was a feature of those later pipes, and must have been dyno tested in house, for them to have been published.
Every pipe I have run thru EngMod makes better power with that design so to me its a no brainer nowdays.

Is it possible to indulge my idle curiosity and run it with a sim of a pipe/engine combo with the tuned length altered to see what it actually does? assuming it fits within the parameters of the sim.

I had a look at his pipe calculater and it appears to be similar in factors to a program I seen years ago based on Blair, think it was on a Kart site

[wobbly]

Yep already done it.
Here is a WR200 sand drag engine.
Baseline curve,50mm tube added to the rear cone, then 25 added to the diffuser and 25 added to the tailcone.
The long pipe is nowhere near optimised ( it detonated in the midrange ) but as you can see a "proper " pipe works hugely better than simply adding
a lump into the tailcone - dumb.

[husaberg]

Yep already done it.
Here is a WR200 sand drag engine.
Baseline curve,50mm tube added to the rear cone, then 25 added to the diffuser and 25 added to the tailcone.
The long pipe is nowhere near optimised ( it detonated in the midrange ) but as you can see a "proper " pipe works hugely better than simply adding
a lump into the tailcone - dumb.

Thanks Wob, I will test your patience further, what happens if the tuned length (including adding the tailpipe lump was kept to the same value) as the optimised version.
It looks odd that the curve shape remains similar than the just tuned length alteration would suggest.
I know it will likely be poos I just want to see what it on its own does.
might I suggest blue black and yellow cause I am colour blind as well a bit thick.;)

[wobbly]

Na, the original info tried to indicate that the tube added to the rear cone was awesome, then ignored the tuned length change.
But if I add 50mm to the rear cone, then the header and diffuser will be way too short to be correctly proportioned, if I reduce them by an equal amount - so then we are not
dealing with the "same" pipe at all.
I could see on the screen what was happening near peak power - the front 2/3 of the pipe acted like normal, except the return pulse was much lower, follower by
a long slow rolloff of the pulse after the Ex port was closed.
So the thing sort of acted like a normal design, just with a shit rear cone that was working way too late in the cycle to be effective.
I tried parallel spacers in the diffuser and the rear cone many years ago when I spent 3 months full time on the dyno to design a totally new KT100 direct drive pipe.
They didnt work in that application, but what I ended up with was seriously weird having the steepest diffuser right after the header.
The so called Wobbly 3 Cone pipe I built over 2000 of them all by hand, and the things are still searched out by people wanting to win KT races.
So here is the baseline Vs the long rear with 50mm removed from the diffuser - even dumber.

[Larry Wiechman]

I tried parallel spacers in the diffuser and the rear cone many years ago when I spent 3 months full time on the dyno to design a totally new KT100 direct drive pipe.
They didnt work in that application, but what I ended up with was seriously weird having the steepest diffuser right after the header.
The so called Wobbly 3 Cone pipe I built over 2000 of them all by hand, and the things are still searched out by people wanting to win KT races.


I've heard of this, but never seen one. Can you teach a little more about this concept? Direct drive would seem to be a hellish challenge to a pipe design.

[wobbly]

The KT100 in direct drive application has to pull from 8,000 to 16,000 - a tough call, and against a huge number of pipe designs that were
mostly derived from 100cc european kart engines.
The KT100 Ex port exit is way too big, so I made the spigot a reducing taper, this then exited into a normal widening tapered header.
One popular variant for high rev motors started with a bigger diameter at the flange face - creating a reversion step as well as a smaller nozzle.
The length spacers are between the pipe entry and the header exit.
I tried spacers up at the flange but they could never match the power of the reducing, expanding concept.
The pipe has 3 diffuser cones, the steepest at the front - then 2 rear cones inside the main body with varying bleed hole centres along its length.
The bleed hole centres and the body volume can be used to tune out dips in the torque curve.
I found early on that the KT is thermally limited to around 17Hp in direct drive configuration,with any more power on track it would overheat after 2 laps and instantly deto at peak torque,
but responded every time to removing peak and pumping up both ends of the powerband.
No other design has come even close to the powerband width of this setup,with two header nozzles available for the engines that were setup to rev to 16,000 + Vs those setup with more mid
power and only reving out to 14,000+.
They won hundreds of NZ titles, and no I wont be building any more.

[Larry Wiechman]

The thermal limitations are a very real problem. I could never understand the logic of the rear facing exhaust port. The carb side is cooled by air, the exhaust side is cooled by accident.
I've considered making a stainless header, (lower conductivity) that extended into the exhaust duct, with the objective of reducing the duct diameter and insulating the casting from direct exposure to hot gases. The downside would be what the hot tube would do to the returning, fresh charge.
Do you find it easier to design a pipe for a kart equipped with an oil clutch? I think a high RPM, slipper clutch would be an advantage on a bucket.

[wobbly]

I made a spigot/flange with a CNC tongue that pushed into the port bottom to fill the silly S bend in the floor.
But the stewards deemed it illegal.
A cluch pipe is a doddle to design in comparison, needs a big flat torque curve between 10,000 and 13,000 from where the clutch locks in ,to the relatively low peak rpm point.
Also tried an aluminium spigot with an oval to round transition, but it didnt make any more power and wore out quicksmart.

[richban]

Nope, this in effect means the trigger is too close to TDC, but if you need more advance to get the timing lines spot on, then add some timing in the channel
trim boxes down the bottom of the ignition curve page.
You can use these to check each cylinders timing when under load on the dyno, means you can correct for crank wind up and also a crank that hasnt been assembled in phase correctly.
Doing this means you know for sure both cylinders are actually firing when the curve says it should.

Forgot the timing light to do this dame it. Now with squish back in the happy place and a more accurate 15 degrees of timing at peak she has gained more power. But the big breakthrough was opening the power valves sooner. That gave a massive 8 more toques. That should give a marked improvement in corner exit. ( If i am brave enough to pull the trigger early ) Thanks again to all that have offered time and advice as this bike has come together. Time to polish it ready for a summer of racing.

[wobbly]

To show you what the tube in the rear cone actually does ( when the diffuser is shortened to get the TL equivalent ) here is the
Ex port pressure traces from the Baseline, and the Long Tube rear.
Note the height of superposition, the pressure ratio at BDC,and the height and shape of the return pulse in relation to EPC.
Now you can see why the fabulous idea makes less power everywhere - except in the inventors head.

[Larry Wiechman]

Good stuff, Wobbly!
What causes the higher pressure ratio peak after EPO?

[wobbly]

With the rear cone extended out by a tube, the reflection from the initial part of the area reduction is reduced, thus the lower
max pressure ratio, then there is a period of no reflection whilst the wave travels down the tube.
Lastly we have the weak return wave from the final part of the rear cone, but its too late in the cycle as the Ex has closed.
The sim is like the dyno, it tells no lies unless you tell lies to it ( or yourself more importantly ).

But - when EPO we have residual pressure sitting at the port face, then the piston cracks open and the pressure wave from the combustion process starts to travel down the duct.
I have the sim pressure recording at the bore edge, so what you are seeing is the pressure ratio rising as the piston decends, then the pressure at the port dropping as the expanding wave moves
away down the header.
Finally the diffuser starts its negative pressure ratio action, sucking on the transfers as the piston dwells at BDC.

[breezy]

wobbly, if a bike came to you with an exhaust as shown in your dyno graph, could it be made to work by changing the programable ignition ?

[wobbly]

If you look at the graph where I compared the baseline pipe to a 50mm longer proper pipe you see that the longer new one
did exactly as it should - make a heap more mid power, less peak but a wider spread under the curve.
I did note that the longer pipe was detonating in the mid range, again completely as expected due to me not having optimised the timing to suit
the big increase in low speed power.
So the longer pipe could be made to work even better with a bit of time spent chasing the TubMax numbers, but the pipe with the tube in the rear cone
is simply never going to work anywhere near as well,no matter what ignition timing it is given.
At lower speeds the rear cone does widen the return pulse bandwidth, but that achieves nothing as the return pulse is not timed correctly anyway.
At peak and beyond, the return pulse is lower in amplitude, and the delayed extra kick from the last part of the cone is so late it does nothing,due to its action happening when the piston has
closed the port.
All I did to create the longer pipe was add 25mm to the diffuser, and 25mm to the rear cone - even that isnt optimised at all, as the ports are set to be working best around 1000 rpm
higher than the pipe, so all in all the whole concept of the tube extension is flawed and wont be setting any new benchmarks for power now or in the future.
Dumb then dumber is the short answer - forget this shite give me something interesting to analyse.

[RomeuPT]

Wob, I think I post this question before, but not in real terms.

Could any engine get the best from a pretty big strong tail cone but at the same time having the last part of diffuser angle the sharpest and the inicial diffuser very shallow, thinking about charge lost because of bad port design. Would a taper mid section have anything to this, what usualy happens in the pressure simulator with a taper mid section?

Saying the TZ750 didn't make more power with more then a 108mm belly made me thinking about banshee, mostly of the aftermarket pipes have no more then 105mm max belly diameter, I found the banshee ports reasonable and always thinked the pipes are that way to make the engine power band proper for the terrain but I am not sure.

[wobbly]

The sharp rear cone will pump up the peak number at the expense of powerband width, and yes the diffuser shape you describe will help crap ports
as it wont be pulling a big depression before bdc and cause the loop to short circuit early in the cycle.
Taper mids are just a way of balancing how much diffuser "power " you want vs the effectiveness of the rear cone.
The taper is so small, it in itself has no real effect on the pressure ratios in the sim.
Remember as Frits said there is only a finite energy available, and a taper belly is one way of twisting around where that energy is used to achieve a particular end goal.
Banshee ports are "not bad " but suffer from old fashioned axial angles - the B ports are angled up sharply.
The A ports are quite flat and dont like a very strong diffuser action, but for sure they are better than an old TZ750 layout that has a very wide and flat A port.
There are some quite fat Banshee pipes like Shearer inframes, and these do work alot better than the skinny things I have also seen.

[TZ350]

303140

"O" ringed head and studs, doweled head but .... :facepalm: but it nipped up on the dyno ... :o even with the jammed rings it still made near 9.5 hp . :)

[TZ350]

Very slowly plodding through. I'm not far into the (ESE thread) thing, still reading 5 year old posts, but wondering how "TZ350" made out with his experiments on cylinder cooling. I've always thought that the front wheel of any motorcycle is a terrible obstruction to engine cooling, and that big ugly air ducts would be the solution (for air-cooled barrels anyway).

I Also think you can help the situation a bit by welding some cooling fins to the first several inches of the exhaust header-pipe, right after the mounting flange. As we all know, the megaphone section of the expansion chamber draws some fresh air/fuel charge some distance into it, and this is then crammed back into the cylinder at exhaust-closing by the positive return wave from the baffle cone (in Seattle, in the first days of expansion chambers, we boatracers called them "bounce-pipes.). This column of air/fuel picks up heat while it is in the exhaust tract; I'm guessing it would pick up less of this heat if the header-pipe had cooling fins.

I did this, welded some cooling fins to the header pipes, on my '76 Yamah RD400C when I made a new exhaust system. But I did no before-and-after testing of that feature in isolation. I don't race it, and ride it like an old lady (I'm old, I never raced bikes, only boats, and I don't mind a splash but don't want to crash), so can't tell you anything about the practical effect of the fins, sorry.

Actually, there is some evidence seemingly supporting my idea, from the sled (snowmobile) racers (who have some interesting 2-stroke tech, if you want to check that out). When the pipes on a sled get hit by a big load of snow, they cool off, the wave-speed slows, and they go out-of-tune until the snow melts off.

Same thing can happen with racing outboards. The sled guys sought to prevent this by wrapping their pipes with thermal-insulating wraps. They soon found that it was best to leave the first several inches of the header-pipe uncovered, no thermo-tape, because of what I'm talking about, an over-heated slug of air-fuel getting shoved back into the cylinder.


Thanks for the tips and the example from your own work and relating the experience of the snow sleds, I am encouraged by the idea.

303141

I too think a lot of heat enters the cooling system from inside the exhaust duct and on my latest air cooled motor I am building, I plan on fitting a finned copper (or alloy) spigot that goes as far back into the exhaust duct as possible and which has cooling finn's on the outside.

The spigot will be a loose fit in the exhaust duct to cut down on heat transfer from the spigot to the cylinder and by using a small forced air fan and duct directing cooling air over the spigot finns it might be possible to keep the initial header-pipe section cooler and also reduce the heat uptake into the rest of the cylinder.

Air scoops and ducting will be part of the picture too.

[Yow Ling]

Thanks for the tips and the example from your own work and relating the experience of the snow sleds, I am encouraged by the idea.

303141

I too think a lot of heat enters the cooling system from inside the exhaust duct and on my latest air cooled motor I am building, I plan on fitting a finned copper (or alloy) spigot that goes as far back into the exhaust duct as possible and which has cooling finn's on the outside.

The spigot will be a loose fit in the exhaust duct to cut down on heat transfer from the spigot to the cylinder and by using a small forced air fan and duct directing cooling air over the spigot finns it might be possible to keep the initial header-pipe section cooler and also reduce the heat uptake into the rest of the cylinder.

Air scoops and ducting will be part of the picture too.

Wouldn't it be easier to water cool it ?

[husaberg]

Dumb then dumber is the short answer - forget this shite give me something interesting to analyse.

Fair enough Robinson did the sums for I think it was bantams in 56X50.6 54x54.5 and something like 52x58.
From memory the long stroke came out on top but he seemed not to account for the ft/min from memory.
using the sim how does it play out with everything equally stressed out..........

[wobbly]

Dont need to spend hours trying to get the numbers to work in the sim
The short stroker is capable of mechanically going to 15,500 @ 26M/Sec but the port STA is simply unable of supporting any power up there.
Yamaha tried forever to make it happen, but finally gave in with a square engine and won the 250 title with Olivier Jaques around 2000.
Going the other way the 52 by 58.5 is able to generate the STA needed but with the longer stroke is only capable of 13500 rpm absolute peak rpm
whereas the square engine runs out at 14500 when stressed to 26M/sec mean piston speed, as has been proven to be reliable with an Aprilia.
The extra 1000 rpm would easily blow away an equally tuned setup simply due to the gearing torque available for an equal terminal speed.

[Cheesy]

Thanks for the tips and the example from your own work and relating the experience of the snow sleds, I am encouraged by the idea.

303141

I too think a lot of heat enters the cooling system from inside the exhaust duct and on my latest air cooled motor I am building, I plan on fitting a finned copper (or alloy) spigot that goes as far back into the exhaust duct as possible and which has cooling finn's on the outside.

The spigot will be a loose fit in the exhaust duct to cut down on heat transfer from the spigot to the cylinder and by using a small forced air fan and duct directing cooling air over the spigot finns it might be possible to keep the initial header-pipe section cooler and also reduce the heat uptake into the rest of the cylinder.

Air scoops and ducting will be part of the picture too.

Since most engineering is adapting other peoples ideas it may be worth getting a Mazda 13B housing to have a look at. They have an insert in the exhaust port to reduce heat transfer from the exhaust to the aluminium, Im not sure what it is made of but it is hard as hell

[TZ350]

Wouldn't it be easier to water cool it ?

Absolutely ...

303157

Good girl Cinderella Water Cooling.

303158

Bad StepMother, Air Cooling, harder work but much more exciting and possibly rewarding for the adventurous.

303160

Maybe Air Cooling is like Diana and the "Race of the Golden Apples", many have tried and failed, so what chance an old soldier with a limp.

The challenge, risk and possible reward from the air cooled's extra CC's, and the possibility of 40+hp if we get it right, makes Air Cooling attractive.

So if you want an easy life and don't want to race Diana, then don't, but I am going to try my hand.

[TZ350]

Since most engineering is adapting other peoples ideas it may be worth getting a Mazda 13B housing to have a look at. They have an insert in the exhaust port to reduce heat transfer from the exhaust to the aluminium, Im not sure what it is made of but it is hard as hell

Good tip and I will check it out. But unlike a 2T the 4T's exhaust is gone never to be seen again, so I imagine the hard thermal shield in the rotary is about shielding and mechanical reliability however hot the shield gets.

But some fresh charge is drawn into the 2T's exhaust header before being pushed back into the cylinder. And we don't want to heat this fresh charge if we can help it. So a 2T's shield ideally needs to shield the cylinder without getting to hot itself.

[fatbastd]

Sorry all-searched but I can't find it.... What is the relationship between relative air density changes and main jet size change? Was it 5% jet change for every 3% RAD change?

Thanks.

[RomeuPT]

The sharp rear cone will pump up the peak number at the expense of powerband width, and yes the diffuser shape you describe will help crap ports
as it wont be pulling a big depression before bdc and cause the loop to short circuit early in the cycle.
Taper mids are just a way of balancing how much diffuser "power " you want vs the effectiveness of the rear cone.
The taper is so small, it in itself has no real effect on the pressure ratios in the sim.
Remember as Frits said there is only a finite energy available, and a taper belly is one way of twisting around where that energy is used to achieve a particular end goal.
Banshee ports are "not bad " but suffer from old fashioned axial angles - the B ports are angled up sharply.
The A ports are quite flat and dont like a very strong diffuser action, but for sure they are better than an old TZ750 layout that has a very wide and flat A port.
There are some quite fat Banshee pipes like Shearer inframes, and these do work alot better than the skinny things I have also seen.

Yep, those best selling toomey's are very thin, with very shalow diffuser, only a little strong in the very end. They are all around power but also make the best peak power of all aftermarket excluding the dune and drag pipes like cpi, sheareer etc. Kind weird how they work so good.

The banshee fires sparks at both cylinders two times per rpm right!? So a simple ignitech DC-CDI-P works there if setted for two sparks for rpm?

[Frits Overmars]

.. it may be worth getting a Mazda 13B housing to have a look at. They have an insert in the exhaust port to reduce heat transfer from the exhaust to the aluminium, Im not sure what it is made of but it is hard as hellOn the inside it is also hot as hell.



...But some fresh charge is drawn into the 2T's exhaust header before being pushed back into the cylinder. And we don't want to heat this fresh charge if we can help it. So a 2T's shield ideally needs to shield the cylinder without getting to hot itself.You've got that right, TZ. But how do you achieve that? The same way as on a piston crown: polish it.
Shiny surfaces won't absorb any heat; they will just reflect it, and as soon as the heat is gone, so is any reflection.

[peewee]

On the inside it is also hot as hell.


You've got that right, TZ. But how do you achieve that? The same way as on a piston crown: polish it.
Shiny surfaces won't absorb any heat; they will just reflect it, and as soon as the heat is gone, so is any reflection.

i dont understand. is a polished piston top and exh tunell the way to go ? in the past ive never bothered doing such things but if it helps i may try it

[peewee]

Banshee ports are "not bad " but suffer from old fashioned axial angles - the B ports are angled up sharply.
The A ports are quite flat and dont like a very strong diffuser action, but for sure they are better than an old TZ750 layout that has a very wide and flat A port.


i recall atleast one honda engine (cr500) used the same old fashion angles and its a bugger to correct. lift the cylinder slightly to fix the floors and then your limited on the roof angles (unless you sky jack the timings well above 130*). leave the cylinder low to get a decent angle on the roof and your floor angles are shit. honda must have known these angles were no good because im not sure they did it on the 125 or 250cc mx stuff. between lifting and grinding i was never able to get over 20* on the A port and the floors werent quit right either. i gave up and moved on to other engines :2thumbsup

while im thinking of it, you got any recomendations for a good banshee drag racing pipe ? im just getting familiar with the banshees

[Grumph]

On the inside it is also hot as hell.


You've got that right, TZ. But how do you achieve that? The same way as on a piston crown: polish it.
Shiny surfaces won't absorb any heat; they will just reflect it, and as soon as the heat is gone, so is any reflection.

Ceramic coating is also an option. HPC in Auckland do it I believe.

FWIW i think the ex port inserts in the rotaries are inconel. Going back a few years, some models of Datsuns had an insert too - bloody hard to grind out....

[wobbly]

Just one thought to add to the 125 stroke thing - the Aprilia made peak power at 12800 and reved to 14500, if we tune the long stroke in a similar
fashion we will have peak HP at 11800 and peak revs = 13500 to give 26M/Sec.
Peaking at a lower rpm will necessitate cranking the bmep thru the roof,and no one has been able to better the Aprilia BMEP at 12800rpm so who thinks they can do better than Jan Thiel et al.
Not me for sure.

The jetting rule of thumb for diameter based jets as we would normally see in a Keihin carb on a well tuned engine is a 3% change in RAD = 1 jet change.

The ceramic coating works to keep heat from raising the temp of the base material - the ceramic surface IS hot as hell ie NFG for a 2T EX port nor in the squish
band of the piston/head - go coat the rest of the combustion surfaces if you want, but not the squish area - it CAUSES deto, been there, blown that up.

Yes polishing the piston and the chamber reflects the radiated heat and reduces the thermal load, ceramic coating the entire chamber area ( less a ring around the squishband ) works more effectively.

The Banshee has wasted spark, a completely dumb idea invented by accountants.
The much better way is to cut a slot in one lobe, making it 3 equal gaps ie lobe/gap/lobe all the same,then program a P2 to fire 2 coils with 3 lobes.
The split lobe is cylinder 1, I always make this the LH side.

[Cheesy]

On the inside it is also hot as hell.


You've got that right, TZ. But how do you achieve that? The same way as on a piston crown: polish it.
Shiny surfaces won't absorb any heat; they will just reflect it, and as soon as the heat is gone, so is any reflection.

Hot as hell is probably a bit of an under statement. I realise that the air charge goes out the port and back so the inconel insert idea was along the lines of minimising heat transfer as opposed to removing heat (and simpler). Looking at material properties stainless would just as good for a cooler 2 stoke exhaust as inconel.... If it was actually beneficial at all

[Yow Ling]

Thanks for the tips and the example from your own work and relating the experience of the snow sleds, I am encouraged by the idea.

303141

I too think a lot of heat enters the cooling system from inside the exhaust duct and on my latest air cooled motor I am building, I plan on fitting a finned copper (or alloy) spigot that goes as far back into the exhaust duct as possible and which has cooling finn's on the outside.

The spigot will be a loose fit in the exhaust duct to cut down on heat transfer from the spigot to the cylinder and by using a small forced air fan and duct directing cooling air over the spigot finns it might be possible to keep the initial header-pipe section cooler and also reduce the heat uptake into the rest of the cylinder.

Air scoops and ducting will be part of the picture too.

Instead of ducting and fans etc why not put a temp sensor in the header then when its over say 1000°F turn on a pump that sprays water on the skin of the header, wont take much room or weight and wont block the desperately needed cooling air for the cylinder, will be a bit steamy , but no rule against that in the MNZ book

[RomeuPT]

Just one thought to add to the 125 stroke thing - the Aprilia made peak power at 12800 and reved to 14500, if we tune the long stroke in a similar
fashion we will have peak HP at 11800 and peak revs = 13500 to give 26M/Sec.
Peaking at a lower rpm will necessitate cranking the bmep thru the roof,and no one has been able to better the Aprilia BMEP at 12800rpm so who thinks they can do better than Jan Thiel et al.
Not me for sure.

The jetting rule of thumb for diameter based jets as we would normally see in a Keihin carb on a well tuned engine is a 3% change in RAD = 1 jet change.

The ceramic coating works to keep heat from raising the temp of the base material - the ceramic surface IS hot as hell ie NFG for a 2T EX port nor in the squish
band of the piston/head - go coat the rest of the combustion surfaces if you want, but not the squish area - it CAUSES deto, been there, blown that up.

Yes polishing the piston and the chamber reflects the radiated heat and reduces the thermal load, ceramic coating the entire chamber area ( less a ring around the squishband ) works more effectively.

The Banshee has wasted spark, a completely dumb idea invented by accountants.
The much better way is to cut a slot in one lobe, making it 3 equal gaps ie lobe/gap/lobe all the same,then program a P2 to fire 2 coils with 3 lobes.
The split lobe is cylinder 1, I always make this the LH side.

Are you sure about 12800? Isn't more like 13k? Peak torque at 12800 maybe?

[wobbly]

Sorry ,yes I meant to say peak torque at 12800 where the max bmep is seen.
But still a couple of hundred rpm makes no difference to the impossibility of making the long or short stroke variation " better " than what the Aprilia R&D achieved.

[TZ350]

Instead of ducting and fans etc why not put a temp sensor in the header then when its over say 1000°F turn on a pump that sprays water on the skin of the header, wont take much room or weight and wont block the desperately needed cooling air for the cylinder, will be a bit steamy , but no rule against that in the MNZ book

Good idea, I like it and could do it alright, we will have to put it out there and see what the consensus about its legality is.

[Drew]

Good idea, I like it and could do it alright, we will have to put it out there and see what the consensus about its legality is.

That's water cooling. All good for 100cc.

[Reckless]

Instead of ducting and fans etc why not put a temp sensor in the header then when its over say 1000°F turn on a pump that sprays water on the skin of the header, wont take much room or weight and wont block the desperately needed cooling air for the cylinder, will be a bit steamy , but no rule against that in the MNZ book


Good idea, I like it and could do it alright, we will have to put it out there and see what the consensus about its legality is.

I would suggest the amount of water you would need to carry, the pump and the electrics would negate any gains made by cooling the header pipe. We ran EGT sensors on all engines we raced in Gearbox class. Standard equipment with a micron guage which gave track mapping also etc etc. Most of us had laptops.

Secondly spraying water on hot steel would work harden it would it not?? Generating cracks?

I have always wondered why you guys don't run track mapping on your buckets? With the level if tech in this thread I would have thought it was a must have? Unless you are or its banned??

Anyway just really posted to say there is people like me reading this thread with interest and not posting!
Keep it up great stuff :first:

[koba]

That's water cooling. All good for 100cc.

Agreed.

R.E. logging etc, this is budget racing!

[Kickaha]

this is budget racing!

:laugh: You're a funny cunt, ever considered a career in comedy?

[speedpro]

About exhaust ports and ducts. I'm just working on a MB100 cylinder so single exhaust port. The duct still has the standard duct to pipe flange with the step at the top. I've enlarged the port by raising it to achieve the desired timing and widened it to a measured more-or-less 68% of bore width. At the moment the port width reduces to the nearly standard port duct width in about 15mm and then tapers out to the standard duct to pipe flange. My question is - Is there a benefit in keeping the reduced duct cross-section or should the duct taper smoothly from the cylinder face to the pipe flange?
Given the size of the uncovered port versus the duct cross-section at various times in the cycle there would seem to be a benefit in keeping the duct cross-section down and therefore gas velocity up.
The reduction isn't a lot, maybe 2mm per side.
This cylinder has stock untouched transfer ports which even using just the single base gasket are at the desired timing. They of course need modification in both width and port roof angle which will have to be achieved with grinding and Devcon. This cylinder also has Boyeson ports(?) or ducts cut from the reed passage to the transfer passages. Looks like a good thing for flow at BDC.

[husaberg]

Agreed.

R.E. logging etc, this is budget racing!

A guy I work with (a sparky) is mad on model aircraft has all the swish gear FPV heads up display etc his set up features an auto pilot feature that uses GPS weigh points. His set up is not that expensive.
he almost wet himself when I showed him the post Frits did on the pylon racing.

then again I am fluffing around doing f-all anyway:rolleyes:



I think too Wob that you missed my point re the strokes I said I thought Robinson was wrong.....

[Frits Overmars]

I'm just working on a MB100 cylinder so single exhaust port....At the moment the port width reduces to the nearly standard port duct width in about 15mm and then tapers out to the standard duct to pipe flange. My question is - Is there a benefit in keeping the reduced duct cross-section or should the duct taper smoothly from the cylinder face to the pipe flange?My answer: you've got a great opportunity to educate yourself here. Preserve the reduced cross section, measure the power, then modify the duct and measure again.

Mind, if the first measurement makes you happy, don't modify that cylinder - never modify your best cylinder; work on another cylinder until that becomes your best.

[trevor amos]

This is perhaps a question for Frits and/or Wob.

It is well known that having water flowing around the entire exhaust duct is advantageous. However, in situations where the duct has too large a volume is it on balance, better to reduce the volume with a Devcon in-fill and lose some cooling effect, or not?
Welding in-fill to the duct profile is, unfortunately, not a viable option.
Any advice will be most appreciated.

Trevor

[Frits Overmars]

It is well known that having water flowing around the entire exhaust duct is advantageous. However, in situations where the duct has too large a volume is it on balance, better to reduce the volume with a Devcon in-fill and lose some cooling effect, or not? Welding in-fill to the duct profile is, unfortunately, not a viable option.Hard to say, Trevor. I tend to prefer the small duct volume but I can't really say because we never used Devcon there; it may crumble and enter the cylinder.
And Devcon is not famous for its lubricating qualities.

[trevor amos]

Thank you for your comments Frits.

If I fill the floor I can still get about 2/3rds of the duct cooled directly by circulating water, and have the advantage of a better flowing duct. Yes, the Devcon will be a potential hazard, but I will try it and see what happens.

Is there anyone else out there with experience of this dilemma, that can maybe offer advice?

To do, or not to do, that is the question!

Trevor

[Haufen]

Just one thought to add to the 125 stroke thing - the Aprilia made peak power at 12800 and reved to 14500, if we tune the long stroke in a similar fashion we will have peak HP at 11800 and peak revs = 13500 to give 26M/Sec.

Why not let the long stroke engine rev to 14500 also? 28m/s for a 58mm stroke engine at 14500 sounds feasible to me. I mean, there are cars being sold which reach 26m/s in a serial application. And not all of these are sports cars.

[wobbly]

Re filling the Ex with weld - I have just had a go at a cylinder I cut up, and plastered birdshit all over it with alloy stick welding rods.
The rods are available form Weldwell, but you have to buy $150 worth - they are made specifically for easy/quick repairs on your weekend tinny.
Getting inside the Ex duct of a 2T or the intake port on a 4T with a 3mm stick is easy,and i found that if you angled the part such that the liquid flux runs away from
the weld pool, the deposit looks OK and isnt porous.
Is gonna make building up oval Ex ducts easy, where even a mini tig torch is all but impossible to control.
In many many tests I have found that with a single port the best power is found with an exit area of 90% of the effective port area at the bore is best.
So in many cases leaving the duct alone and simply making the port 70% odd and lifting it to normal race timings you end up with the right size exit.
I have tried steps ( with bigger header diameters ) but never found an advantage in this concept when using a single port and 90% exit size.
Reducing the duct vol by lifting the floor a few mm above BDC and filling in the bottom corner rads is what was done progressively more and more at Aprilia
and has a proven results, by increasing average velocity thru the cycle but also reducing the direct short circuiting from the A port front corners.

Re the long stroke rev thing - we were looking at apples Vs apples, and the same scenario could then be applied to the 54.5 engine - rev that to 28M/Sec and it becomes superior again.
But that exercise would then need someone to re employ Mr Thiel and his 100 minions at Aprilia to do the R&D needed to re optimise every single element of the design.

In reality it isnt " well known " that having a cool Ex duct is advantageous - its only lucky people like us that have been exposed to the thinking of people like Frits and Jan Thiel that this concept
sees the light of day.Their Noddy boss at Aprilia didnt agree, and most all of the current manufacturers of 2Ts dont have a clue.I have taken to boring holes and slots in the castings to get water right
up to the flange face like we see in Jetskis ,to try and get some of the benefits available.

[Haufen]

Re the long stroke rev thing - we were looking at apples Vs apples, and the same scenario could then be applied to the 54.5 engine - rev that to 28M/Sec and it becomes superior again.
But that exercise would then need someone to re employ Mr Thiel and his 100 minions at Aprilia to do the R&D needed to re optimise every single element of the design.


I understand your point in comparing apples with apples, but I don't think the square engine would come out on top in such a scenario. Because trying to let the square engine rev to even higher piston speeds, it would run out of time-area, whereas the long-stroke engine would not (yet). I believe there is a chance that, had Jan Thiel started with a long-stroke engine instead of the square engine layout, and put the same effort into it as he did with the RSA, that engine might have even more horsepower. That concept worked by going from short stroke engines to square engines, so why should it not work again by consequently optimizing a long-stroke engine? Maybe you can find out if that path would be worth trying in converting your RSA simulation model into a, say, 52 x 58,8 engine? What do you think?

[peewee]

seems like i asked onetime what the results would be with a undersqaure RSA. from what i recall it was never tried so it would be difficult to answer the question.

[TZ350]

For those interested in such things.

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Does more oil make more power? well I think so.

Chambers finally got on top of the gearbox oil being sucked into the motor problem on Av's bike. We dynoed it plenty of times over the weeks to see if we had stopped the leak passed the rotary valve. Each dyno session it smoked real bad and drank about 200ml of gear box oil.

The night the smoke stopped we lost 4% of the hp we were making when it smoked.

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As all the work was being done on the rotary valve and cover, the piston and cylinder were not disturbed.

So I guess its fair to say that the difference in power is oil related and not the result of any inadvertent change to the piston and cylinder during re assembly.

303203

Playing with Chambers RG50 on the dyno getting the ignition and jetting right..

For those interested in what the Air Correction Jet can do.

303202

Purple Line is the original 170 main jet, Blue line is a 220 main jet and it improved the lower and mid range part of the torque curve. The Red line is the Air Correction Jet opened up to 1mm, clearly more to go, tomorrow hopefully we will get a chance to open the Air Correction Jet up some more.

In the end, with a bit more work on the Air Correction Jet I expect to be able to keep the better lower and mid range pickup of the 220 and have the top of the curve extending out as far as the original 170 main jet did.

The 170 main jet was chosen for peak power, I must be like 100's of other people who do plug chops and all sorts of tricks to find the best main jet for peak power.

But now, in setting up an engine I would be more inclined to choose a main jet that worked well as the engined climbed the torque curve and then bend the top of the fuel curve to get peak power by adjusting the air correction jet.

[trevor amos]

Wob, thank you for that reply and for sharing your experiences.

I wonder if I may pose another question to you and Frits? As I`m sure you know, over at Pit Lane Jan Thiel has been explaining the problems he encountered with the bridges on the auxiliary ex ports of the Aprilia cylinder. Could there be any flow advantage in shortening the centre bridge on, say Honda RS cylinders, and indeed any 2t ex duct with a similar arrangement? I was particularly thinking of the effects during the critical blowdown period, where area, time and flow capacity are all in short supply!

Trevor

[Frits Overmars]

Does more oil make more power? well I think so.So do I. There is a slogan "where there's oil, there can't be petrol". But hey, oil will burn too.
Ever tried CH3NO2? Granted, there are better lubricants, but horsepower won't be a problem.



303203
Playing with Chambers RG50...So Chambers is using an RG50 frame? From the stories on this forum I get the impression that Av knows her racing, so I wonder: did she ever ride that 50?
And what did she comment? An RG50 frame is almost as stiff as a wet newspaper...


Purple Line is the original 170 main jet, Blue line is a 220 main jet and it improved the lower and mid range part of the torque curve. In the end, with a bit more work on the Air Correction Jet I expect to be able to keep the better lower and mid range pickup of the 220 and have the top of the curve extending out as far as the original 170 main jet did.You seem obsessed with that Air Correction Jet. This screams for an of-off powerjet!

[TZ350]

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Chambers had me order one of these today for his RG50.

Pretty cheap of Ebay, it may be a good, inexpensive ignition (hopefully), anyway when it turns up I will let you know how it goes.

[husaberg]

Chambers had me order one of these today for his RG50.

Pretty cheap of Ebay, it may be a good, inexpensive ignition (hopefully), anyway when it turns up I will let you know how it goes.

Careful with the ebay it might be a Chinese, they do a version of the engine. The real ones are not that dear from KTM..The new 09 on engines one is the same too.
I have one here, I probably know where there is a few actually, most people racing them carried spares or knew someone else who did........ They are teeny tiny.........
The KTM's clutch doesn't come in till about 9000 rpm and they rev past 13000 plus are made for a racing 50 so they should be sweet.

They are made be Selecta, I think they made the ignition generator for the RSA too...
Frits would be able to confirm.

[Frits Overmars]

They are made be Selecta, I think they made the ignition generator for the RSA too... Frits would be able to confirm.I would. But in case you wish to Google, try Selettra http://www.selettra-ignitioncoil.it/56/digital_ignition_k.html

[husaberg]

I would. But in case you wish to Google, try Selettra http://www.selettra-ignitioncoil.it/56/digital_ignition_k.html

Speeling correction available by a world renown physicist as an optional extra.......:devil2:

[TZ350]

Ever tried CH3OH2? Methylhydronium, I will need some help understanding this as a fuel?


So Chambers is using an RG50 frame? From the stories on this forum I get the impression that Av knows her racing, so I wonder: did she ever ride that 50?
And what did she comment? An RG50 frame is almost as stiff as a wet newspaper...

Chambers has a RG50/RS frame combo being built up for Av, the RG50's are something us lesser mortals knock about on for shits and giggles and to use as donkeys for developing 50cc motors.


You seem obsessed with that Air Correction Jet. This screams for an on-off powerjet!

Yes its my little obsession, I had under appreciated the air correction jet before, guess most do. And an on-off powerjet would be great, I would love it but it would require a more complicated infrastructure for the RG50s than we want at the moment.

For now I am finding it quite interesting seeing where we can get to by using the main and "air correction jet" to massage the fuel curve.

[TZ350]

Careful with the ebay it might be a Chinese, they do a version of the engine. The real ones are not that dear from KTM...

At $49 USD it will most likely be Chinese, I guess we will see if its up to it. Otherwise I will need some pointers to genuine KTM ones.

http://www.selettra-ignitioncoil.it/53/digital_minibike.html

Actually I have just had a look at Selettra and they do a programmable digital version of the KTM 50 ignition and some real nifty generators.

[Frits Overmars]

Methylhydronium, I will need some help understanding this as a fuel?You're right; that won't burn. It was a typo; it should read CH3NO2, not CH3OH2. Maybe this will help

[Ocean1]

Maybe this will help

What will help is 8.7 times the fuel in every stroke. :yes:

[Peter1962]

Speeling correction available by a world renown physicist as an optional extra.......:devil2:

Husaberg, there is a striking difference in picture 1 and the two others concerning the balance shaft. I do not remember that this specific item has been discussed on the forum, so my question is : what was the reason to change the balance shaft in the aprilia RSA ?

[TZ350]

... it should read CH3NO2 ...

That I understand, I have some out in the shed too....:shifty:

[Frits Overmars]

Husaberg, there is a striking difference in picture 1 and the two others concerning the balance shaft. I do not remember that this specific item has been discussed on the forum, so my question is : what was the reason to change the balance shaft in the aprilia RSA ?Picture 1 shows the original RSA125. The other pictures show 'improved' versions; after Jan Thiel retired, certain geniuses at the Aprilia factory seized their chance to 'correct the errors that Jan made'. For example they padded the insides of the crank webs in order to reduce the crankcase volume 'because everybody knows this should be as small as possible'.
They also changed the left-side balance disk into an asymetrical balance weight because that was a little lighter. They never thought about the windage that such an asymetrical body causes at 14,500 rpm.

Funny thing: those later, improved versions were never as fast as the original RSA...

[wobbly]

Re the long stroke RSA theory - it took Jan Thiel and his 100 underlings god knows how many hours/weeks/months/years to get the real thing working.
Next time I have a month spare to do all the iterations of ports/pipes/ignition etc I might get somewhere near finding out what is possible with a 52/58.8
when simmed correctly, ie it aint going to happen.
It just isnt easy at all.
I do know for sure that up above 14,000 rpm even the tiniest change in something like the combustion parameters VibeA and VibeM make huge variations in the effective spark event.
Likewise stinger diameter, a change of 0.2mm will instantly create no power at all or death deto, luckily I havnt been hit by a rod exiting thru the screen.
The wave action is hugely powerful at that level of bmep and rpm, trying to simulate reality correctly is just as hard ,I believe, as actually doing it in the workshop.

Re the T bridge on a RS125,I dont think any advantage is to be had in actual out flow characteristics by shortening the bridge - the biggest blowdown effect is gained by having the correct
radial hooks just outboard of the bore.
Reducing the heat radiating area of the bridge affecting the backflow temp may well be a gain, you will have to wreak a cylinder to find out I guess.
I have seen several tuned cylinders with the top of the bridge alot shorter in length than the bottom.

I havnt tried the Selletra ignition you have shown ,but in a KZ2 the homologated Selletra equivalent of the PVL for ICC classes makes around 1.5 Hp less from 11.000 upward in a straight back to back.
The timing curve is identical - so it can only be the energy level in the spark gap causing the issue.
For any single race engine now I always use a P2 Ignitech and fire both CDI channels into a single low impedance coil, its the only way to better the power produced in a RS125 Honda for example
as this has a DC DC CDI from the factory.

[trevor amos]

Wob, once more, thank you for your thoughts on the bridge question.

I certainly don`t fancy destroying a good barrel to prove a moot point, if you can`t see an obvious benefit then I would have no chance to be able to reason it through!

Trevor.

[TZ350]

Getting ready for Mt Welly tomorrow.

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Chambers RG50.

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NedKellys RS/Aprilia 50 with pumper carb.

The RG50's :- https://www.flickr.com/photos/sonscc/sets/72157647372063815/page2/

[TZ350]

Someone asked me about how I was going to arrange the cooling fins on the Beast.

303288

I did not want to rely on turbulent air randomly blowing over the fins. My plan is to angle them and use ducting to direct an air blast onto them that aggressively scavenges between the fins right down to the roots. And to arrange some more ducting to carry the hot air back to the low pressure area behind the bike. That way cool air is directed between the fins and the warm air is effectively drawn away.

With the motor angled down, the RS pipe slots in perfectly and with the steep angle I will need to run a dry sump arrangement for the gearbox to avoid flooding the rotary valve and clutch while the gears are starved of oil.

The plan is for the gearbox oil to drain into a catch tank and then be pumped back and splashed over the gears. And while I am at it, the catch tank might as well have some cooling fins and ducted air too.

[husaberg]

Someone asked me about how I was going to arrange the cooling fins on the Beast.


.


303288
What size is that chain going to be:nono:

[TZ350]

What size is that chain going to be:nono:

The team had settled on 428 and have a large selection of sprockets, but I favour 415 for this project and could trim some wider 428 sprockets to suit.

[diesel pig]

The team had settled on 428 and have a large selection of sprockets, but I favour 415 for this project and could trim some wider 428 sprockets to suit.

It may have the same pitch as 415 but 428 has bigger dia rollers so it will not fit I am afraid.

[TZ350]

It may have the same pitch as 415 but 428 has bigger dia rollers so it will not fit I am afraid.

Thanks for the heads up ...

[lodgernz]

Wobbly suggested I use Devcon to contour the roofs of transfer ports.
I see there are several Devcon "plastic steel" epoxies. I'd appreciate it if someone would point me at the best product for this application.

[Yow Ling]

Wobbly suggested I use Devcon to contour the roofs of transfer ports.
I see there are several Devcon "plastic steel" epoxies. I'd appreciate it if someone would point me at the best product for this application.

this stuff is good and easy to work with http://www.no8online.co.nz/mainmenu19/cat17/Epoxies+Acrylics/p245/Steel+Quickset+Epoxy.html

[F5 Dave]

420 can be taken down to 4.3mm from memory to use 415. 428 cannot. Don't forget to bevel the edges of the sprocket and fronts can be souper hard. Just skim the outer area and watch offset to stay consistent.

[peewee]

he might of been suggesting this devcon http://www.devcon.com/products/products.cfm?brand=Devcon&family=Aluminum%20Putty%20%28F%29

this stuff works pretty good also http://www.polymericsystems.com/epoxies-adhesives/epoxy-putty-tapes/kneadatite-blue-yellow.htm

if you plan to use any of it with methanol , do a test before applying it to the engine because some epoxies wont stand up to methanol but i think most will do fine with gasoline. might not be a bad idea to test it against the particular gas you plan to use just in case theres a problem with the compatability

[seattle smitty]

You're right; that won't burn. It was a typo; it should read CH3NO2, not CH3OH2. Maybe this will help

New member here, old Yank outboard racer, mostly 250cc Hydroplane, 45 years ago (and maybe again soon):

Mr. Overmars (and any and all other real dedicated 2-stroke gear-heads), in my entry in the New Member section, I've laid out a welcome mat for those of you who got legislated out of GP bike racing, and who might be open to a form of racing that rewards pure 2-stroke horsepower. We outboarders commonly burn methanol, and we are free to try nitro and such other exotic (liquid only) fuels as we think our engines can be made to survive. (If anybody cares to hear a little more about it, go to the New Member section).

I expect to just be a lurker here for a while (with a thousand pages to catch up on!!!), but hope to start occasionally adding my 2 cents worth at some point. But seeing the reference to nitro, I had to make my little sales-pitch . . . .

[Grumph]

this stuff is good and easy to work with http://www.no8online.co.nz/mainmenu19/cat17/Epoxies+Acrylics/p245/Steel+Quickset+Epoxy.html

That's a bit low temp for safety, Mike. Devcon seems to be safe to around 100C and there's a Loctite filler which is safe to about 120C - and cheaper than Devcon too.

[Yow Ling]

That's a bit low temp for safety, Mike. Devcon seems to be safe to around 100C and there's a Loctite filler which is safe to about 120C - and cheaper than Devcon too.

Good point I was thinking watercooled motor