ESE's works engine tuner

[TZ350]

Page 1000

On Page 500, Bucket has links to how Team ESE built their 26, 28 and 31 hp engines:- http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page500

And Micks post below is your most useful tool for finding all the other good stuff on the Team ESE (or any) thread, try it.

… some may find this useful. Rather than use the site search, which usually fails.
Use Google to search this site, just use an ordinary search phrase and after it add
site:www.kiwibiker.co.nz
for example
Frits pisa site:www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/
Mick

What F4 or Bucket racing is all about:-

Video from yesterdays F4 cup, filmed from GPR bike no 11

Here is the first 15min of the BOB , Riding with Mr BucketRacer

Here are some other very interesting threads:-
Foundry:- http://www.kiwibiker.co.nz/forums/sh...Foundry/page29
Team GPR:- http://www.kiwibiker.co.nz/forums/sh...post1130775246
Frame and Chassis:- http://www.kiwibiker.co.nz/forums/sh...chassis/page38
Chris C's photos:- http://www.kiwibiker.co.nz/forums/sh...-warning/page5
Old #6:- http://www.kiwibiker.co.nz/forums/sh...68694-6/page49
Bucket Lap Records:- http://www.kiwibiker.co.nz/forums/sh...-records/page8
Photographic History of Bucket Racing:- http://www.kiwibiker.co.nz/forums/sh...t-racing/page3
Ecotrons engine management:- http://www.kiwibiker.co.nz/forums/sh...nagement/page5


2T Engine development software:-

Porting Program http://www.porting-programs.com/

EngMod2T http://www.vannik.co.za/EngMod2T.htm

There is an option in "Thread Tools" to download the complete text off this thread.

There are also over 7000 images on this thread, use "Thread Tools" to view them and then click through to the original post about them.




Page 600 is worth a look at:- http://www.kiwibiker.co.nz/forums/sh...-tuner/page600

A Link through to Husaburgs vast library of pictures.

NSR500 Porn
I will be adding some more later including
Honda RS125 Aprilia GP bikes YZR500 Swiss auto
Rotax and other Tandem twins RGV500 Kenny Roberts 3's
Cagiva Carbs fuels intakes and stuff

I put together a bit of a photomontage of Neil’s many many projects i haven’t put them in order yet. One word describes Neil ...........Prolific

http://www.kiwibiker.co.nz/forums/al...p?albumid=4864

if you can't see the album don't blame me.

Its worth the visit ......

And there are also over 7,000 images on this thread. Follow the link below and you will find screen shots of the process.

How to view all the images.
Go to Thread Tools at the top of the page and View Thread Images.
Now roll to the bottom of the page.
Here you can sort them from the beginning.
70 to a page, there are 6,000+ images
If you find something interesting just click on the images title and it will take you to the original post.

Blowdown STA (Specific Time Area) is everything and determines the RPM ceiling and power output of your motor.

Optimum Exhaust Port Duration is 190 deg but blowdown STA requirements may force you to use a longer exhaust duration.

Do I understand this correctly, given sufficient blow down and exhaust STA an exhaust duration of 180 deg would be the optimum at any rpm?

The short answer is yes. (the long answer is) … the initial pulse starts moving as soon as the exhaust port starts opening. More or less true, but we are not interested in the first weak appearance of the pulse; we want to know when the pulse reaches its maximum amplitude. And that requires a certain amount of open exhaust port area. It turns out that for our desired theoretical exhaust timing of 180° we will need a geometrical exhaust timing of about 190°, depending on the shape of the port: does it open gradually or does it open over its full width all at once.

The obvious question will be: why has the Aprilia RSA125 a geometrical exhaust timing of about 200°? True, at 190° the maximum torque value would be higher, but the engine would not want to rev because the blowdown time area would be too small.

The 200° duration is a compromise: a bit less torque and a bit more revs; as long as the torque decline is smaller than the rpm rise, we gain horsepower.

Wob often refers to the vital dimensions and Frits posted a diagram of them. Stick to these %%% to get good results.


Frits suggested design criteria for a good pipe.



Click on Husabergs link to read about transfer port angles.

I tried to post a little technical story here to help you through the Christmas days, but I could not manage to insert the pictures the way I wanted to...
But in case you're curious, you might want to take a look here: http://www.pit-lane.biz/t3173p657-gp...-part-2#134197

Transfer Port Theory

Transfer Ports. Low and Wide is the go….

The lower the transfer timing, the less risk of too-early returning exhaust pulses shoving the cylinder contents back into the crankcase.
In short: lower transfers give a better powerband, all other things being equal (which of course they never are).

The 135mm inlet tract length from tip of reed to carb bellmouth rule of thumb.

I discovered the 135mm inlet rule of thumb on a TM125 MX engine used for 125 class kart shifter racing . That is the length for a reed - the RV needs to be a lot shorter again.

Frits's version of a short carb setup.

The Aprilia's inlet disk diameter. From memory I would say it was 126 mm.

Optimized disk inlets do not generate pulses: you open the disk when the crankcase pressure is equal to the pressure just outside the disk. Opening it any sooner would cause a loss of mixture to the outside world; opening it any later would be a waste of time*area.
You close the disk when the inlet flow has come to a stop. At that moment the pressure at the outside face of the disk will be equal to the pressure in the crankcase, but it will be higher than the atmospheric pressure, so there will be some blow-back, but that does not come out of the crankcase (assuming your closing timing is spot-on); it is just mixture feathering back from the high-density zone outside the disk. For that matter, every conventional inlet system (disk, piston, reed) will show the same blow-back tendency. And it may not be even visible from the outside; maybe the cloud of blow-back moves just a few centimeters and never really exits the inlet tract.
By the way, closing an inlet disk too early (or revving the engine higher than the inlet system's frequency would like to) will generate serious blow-back because then the closing disk interrupts an inward-bound flow which will violently bounce off the disk.
You can observe this very nicely on a dyno: looking into the carburetter you can see the fuel spray exiting the mixing tube and curving towards the crankcase. But rev it high enough and you will see this curving change into a steep front of mixture.

A lot of the decade pages have collections of quotes and links to other interesting things.

Page 990 Blowdown STA, Ex porting plated cylinders, port layout and port angles.
Page 980 No links list but there is talk about spark energy and EGT
Page 970 Fuel - Oil and EGT talk
Page 960 Wob - Fuel and Oil Talk and Crank inertia.
Page 950 Its all about exhaust blow down …..
Page 940 Fixers 50cc adventures – ports & heads – Wob talks about Bad Gas.
Page 930 Frits 50cc pipe – Husburgs large links list, parts books, steering head brgs
Page 920 Big links list, allsorts. Tokoroa GP videos.
Page 910 No links list but the page is about fitting a 12V generator stator.
Page 900 Frits thoughts on O2 sensors – EFI Fueling theory – Wob on EGT
Page 890 DIY Foundry tips – EFI data – Detonation Management (tec paper) – more EFI
Page 880 Big list of Flettners Foundry posts and pictures.
Page 870 YZ & Bighorn Dyno results – Dyno Vids and EFI talk
Page 860 Air cooling and ducting and Carb air inlets, next page Greymouth Race
Page 850 1st run of the EFI Beast
Page 840 Husaburgs big links list on Power Jets – High temp epoxy and Ex port dam.
Page 830 Plugging piston pins – Cyl Heads (no radius) and Plug to Piston distance.
Page 820 Det sensor & Ignitec setup – Exhaust port dam – Boost Bottle – Insulating Paint
Page 810 Links – about Razing the Exhaust port floor
Page 800 Link to dyno graphs for the YZ & BigHorn EFI Bikes & a lot of EFI stuff
Page 790 Car & bike museum pics _ Wobs pipe.
Page 780 Setting up an IgniTec DC-CDI-Race-2 ignition – Big list of links.
Page 770 Wobs views on triple ex ports – first run of the EFI YZ250
Page 760 Port Angles – lots of Pipe design info – Fast model aero engine.
Page 750 Case Com – Basic 2T tuning – BigHorn EFI
Page 740 Case Vol – Deto – Inlet Length – Over rev deto.
Page 730 Pipes – Deto – Lambda – Temp probes – CrankCase CR – Variable headers.
Page 720 Inlet tract length – GP125 service manual – Picture of how to read a plug + Wobs comments
Page 710 Fuel and Power Jets - EGT and CHT - Crank build
Page 700 Talk about wide and low transfers – Case volume and dyno graph – det and Lambda sensors.
Page 690 Pipe talk and ideas about making mufflers.
Page 680 Talk about the Trombone pipe and more of Frits and Wobs views on pipes.
Page 670 Pipes – blowdown STA numbers – Trombone pipe.
Page 660 Lots of links on pipes – Ariel Arrow – and CVT
Page 650 Links – Frits and Wobs views on pipes – CVT transmissions – 30 vis 24 carb dyno graph
Page 640 Links to Wobs views on pipes – crank balance factor – connecting a laptop to the Ignitec
Page 630 More of Wobs views on pipes – Frame & wheel weights – correct O ring grove sizes
Page 620 Links to Cooling Water Flow – Case Comp and Pipes – Setting up 2T carburation.
Page 610 Simulation packages – combustion efficiency – transfer ducts – chamfered exhaust top edge.
Page 600 Books that can be down loaded and Frits talks about why 190 Ex duration is so good.
Page 580 No links but page is about mounting carbs and the 24mm pumper carb & 28hp dyno graph.
Page 570 No links but the page talks about carburation – emulsion tubes and pilot jets.
Page 560 No links, the page is mostly about 96 vis Av gas with dyno test.
Page 550 No links list but the page is mostly about TZ400 build and cranks and rods.
Page 540 No links, the page is mostly about Wobs success with the 400 project.
Page 530 Ignition – setting up det sensors without a dyno – wings inside reed valves – poly quad head
Page 520 Mostly about what some wheels weigh, ATAC valves and crank stuffers.
Page 510 Bucketracers general Links List
Page 500 Bucketracers links list of how to make a mid 20’s hp Suzuki GP125

Page 500 .....

No need to have a peaky engine. Here are Two Very useful Tools. EngMod2T a 2-Stroke simulation package and a handy (and cheep) Porting Calculator from:- http://www.porting-programs.com/ which is based on Blairs work.

Because a few people have asked about the GP engine, to save wading through 270 pages, these links go to the more relevant posts about the 27hp engine. Different link collections can be found on the decade pages 80-90-100.....260 etc.

27rwhp 1978 Suzuki GP125

EngMod2T

For something different Page 400 is going to be the basic info for building a 30+hp Suzuki GP125 taken from the EngMod2T simulation files.

Crank HP. Simulated Dyno Graph from EngMod2T using an early RS125 pipe.

EngMod2T's main screen for developing the model.
Basic engine dimensions.
Exhaust port dimensions.
Transfer port and duct dimensions.
Transfer port cylinder entry design and angles.

There are over 3,500 images on this thread. To find the interesting ones use Thread Tools near the top of this page and View Images, then sort them from the Beginning and 70 to a page. Click on the Image to view it and the little N/A sign to go to the Post about it.

On each decade page, 490, 480, 470, 460 etc there is a collection of links or a collection of the more interesting technical posts from the last ten pages.

A bit of an index .....

Page 490 The Trombone, Ex port resonance and Transfer port stagger.
Page 480 A vid of the Trombone, transfer timing and hot gases entering the transfers because of insufficient blow-down for the rpm.
Page 470 Blow-down STA ... Specific Time Area.
Page 460 No list but the page talks about Boost Bottles.
Page 450 Links to the basic info for building a 30+ hp Bucket.
Page 440 No list, page talks about power and air correction jets.
Page 430 Carb inlet lengths and crankcase volumes.
Page 420 Transfer ports and the importance of the up swept angles, the Leaning Tower of Pisa principle explained.
Page 410 Rolling road dynos, main and power jet ratio.
Page 400 Links to the basic info for building a 30hp Suzuki GP125 Bucket engine.
Page 390 Links to Frits collection of Aprilia stuff.
Page 380 Transfer duct shape and STA's.
Page 370 No list but the page talks about Jan Thiel and racing 50's.
Page 360 Frits chamber calculations formula.
Page 350 PJ switching, Wob and crank shaft balance.
Page 340 Muriatic Acid, main brg float, Husburgs con rod dimensions.
Page 330 No list, page talks about expansion chambers, race gas.
Page 320 High temp silicon, Yama Bond, crankcase sealing, air solenoids Vid clips of Mamola.
Page 310 Copper for cooling, sprockets for cooling, steering head brgs.
Page 300 How to determine STA numbers.
Page 290 B/E dimensions, delivery ratio, Honda Ex Step, stinger nozzel
Page 280 Aprilia RSA port layout explained, pumper carb, links to gluing up the GP cases.
Page 270 Link list on how to make a decent high 20's hp Suzuki GP125 Bucket engine.
Page 260 Over rev cough and what it means, Mallory metal for crank balancing.
Page 250 27hp from a 1978 Suzuki GP125
Page 240 Aprilia RSA cylinder stuff.
Page 230 Porting Calculator and a lot of other useful tech links.
Page 220 RG50 part numbers, 2-stroke carb atomisers explained
Page 210 Page is mostly about the results from the TRRS
Page 200 Simple 18 hp Suzuki GP Bucket engine using a RG250 pipe.
Etc ...

pit-lane.biz is another really good thread:-

http://www.pit-lane.biz/f34-gp125-et-250-snif

http://www.pit-lane.biz/t5121-gp125-...vermars-part-4

http://www.pit-lane.biz/t4072-gp125-...-part-3-locked

http://www.pit-lane.biz/t3173-gp125-...-part-2-locked

http://www.pit-lane.biz/t117-gp125-a...-part-1-locked

Go to the NSR site it has a lot of info including the fuel curves I think.
http://nsr-world.com/tuning/250-tuni.../carburettors/
http://nsr-world.com/tuning/250-tuni...index/jetting/
Attachment 302500Attachment 302501

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

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

Ed Tuck racing (NSR250):- http://edetuckracing.blogspot.co.nz/...5-pistons.html

http://www.twostrokeracelab.com/

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

I thought I'd seen a few photos that looked veglia familiar!

I found quite a few photos in this thread (I turned up in a web search for photos of the Scitsu plate frame) that I've copied off to my PC for my future reference.

No need for formality, my name is Michael (not Mike though) so feel free to use it. "Mr." makes me feel so old . . .

For those who aren't familiar with my website this page

http://www.eurospares.com/other.htm

will get you to the various project pages and the pages with links to somewhere around 6000 images of bikes and parts I've found interesting. I started the site nearly 20 years ago and I've retained the largely text-based format that was needed in the low bandwidth days so people have to guess from the descriptions which photos they are likely to want to look at. As you can imagine, going back and adding thumbnails to all the existing links is quite a chore. And I've got plenty of other stuff waiting to go up -- someday.

cheers,
Michael

[TZ350]

The trombone Pipe ...

This graph sticks in my mind ... it had three beautiful overlapping curves. I had to search for this but this was pretty profound, I along with plenty of others had our thinking a little back to front.

Husabergs post is worth a visit, as there are a lot of links to seriously good pipe stuff.

Pipe design elements relating to variable with pipes
Frits Overmars
A powervalve does not really give you real resonance power; it just prevents the pipe pulses from completely messing up the power curve at low revs. I expect a sliding pipe will make more low-down power.
http://www.pit-lane.biz/t1666p15-tec...ht=twin+rotary

The Aprilia RS123 as it has a powervalve is able to be tuned to a higher level over a shorter range than if the PV wasnt installed. In general a steep angle rear cone creates a high peak power number in a narrow band with severe roll off of the power after peak.

Something I cant explain is that quite often in a sim having a small steeper section of cone down at the stinger will create more power - like was used by Aprilia in the RSA / RSW. But in many dyno tests of this, in reality, it doesnt work any better than a single angle - the same result for a shallow section up at the mid followed by a steeper section.
Both scenarios can be equalled or bettered on the dyno with the correct single cone.

For practical purposes 28* included is about the limit for a single cone,but there are special cases like the RS123 where having a powervalve, and a rev limiter you get tuners ( like Arrow ) that want a big number to advertise and sell pipes, so they use a REALLY steep angle as it doesnt matter that there is no overev power.

You may get an improvement in power, over a narrow band with a very steep rear cone, but its a special case where running a very low port timing with a severe rear cone and is not something I seriously want to even think about.



Here is the Arrow design, really dumb with incorrect header length etc, but it gives the result they intended.

I am thinking about build a replica of Honda A-Kit pipe to test on my engine, I did this a couple of years ago, Looking for the drawing It can be seen a parallel 120 belly, other drawings have a slight increase diameter in the mid section about 1º or so, is this a good thing most of the time? What is the effect on the pressure bench? Thanks

The Honda A Kit is VERY old tech, it was basically the design Harold used on the lovely KTM GP efforts and was one ( main ) reason they were never really fast enough.

If you must copy something go with Aprilia Tubo 100+ layout, less the multi angle rear cone.
But using a 800mm tuned length with a very low exhaust port duration is off on a very weird tangent and who knows what result this will give you.

The A kits had 200* duration with that short pipe and needed every ignition trick and electronic powerjets to make that work correctly.

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%.

Varying the length of the 1st diffuser changes the shape of the depression curve at and around BDC, thus tailoring to front side or overev power.

I am not sure what model this is but Frits posted it as the last honda pipe.

Case com is a very complex subject but a few rules of thumb apply.

The higher the bmep of an engine then the higher the delivery ratio, thus a larger case can store the higher volume of ingested air at a higher pressure and this is then available to the transfer ducts.

But the quality of the duct and port geometry also affects the case com required.

The smaller the case vol (higher ratio) the greater the pressure rise in the case as the piston drops - this suits compromised transfer ducts with little or no inner wall shape, as it helps force the flow around through the ducts quicker.

Good duct/port geometry allows the use of a bigger case as they don’t need a large pressure ratio across the port to initiate good flow.

Lastly is the effect of the pipe geometry, the diffuser sucks like hell on the Ex port around BDC, pulling flow through the transfers, and it is important to match the pipe diameter ( and thus the diffuser included angles) to the transfer port/duct geometry.

Suck too hard on crap transfers and they loose directional control - giving greater short-circuiting out the Exhaust port.

Thus you have a Catch22 in that you need a small case to speed up the flow, but this limits the available stored mixture, and you want to suck on the transfers as much as possible, but not so much as to loose the control of the flow direction - or to speed up the loop velocity excessively thus reducing the trapping efficiency..

One myth that needs busting here is, that the bulk of the flow through the transfers is initiated by the piston dropping. This happens in lawn mowers, not racing engines.

Pipe diffuser suction when the piston is around BDC forces the bulk of the flow volume, NOT the pressure in the case forcing flow up the ducts.

When the transfers open there is more pressure in the cylinder than in the case. Thus we get flow reversal at the initial transfer opening point. This also means that the transfer port that opens first - flows last, as it has the greatest flow reversal affect, down the duct.

In general, high bmep engines that by default will have good port/duct geometry, will like a case com down near 1.3:1, lower performance engines with crap transfer/duct geometry will perform best with the ratio higher, up near 1.4:1.

Thus as you develop an engine, increasing its efficiency with better porting, then this will allow the use of a bigger case, and bigger pipe diameter/vol, to work with that - the two go hand in hand.

Dont get hung up on Bl - STA, thinking its good to get rid of the transfer blip Any well developed race engine is ultimately Blowdown restricted, and you will always see the Tr Port pressure ratio rise when they open. That effect is what makes port stagger work. The first port to open, initially has backflow, it must, as there is more pressure above than below. Then the rest of the ports open and eventually begin to flow into the cylinder due to the depression created by the pipe diffuser.

Thus the port that opens first, flows last. Counter intuitive, but reality, proven on motored, instrumented engines in the lab and reported in a raft of SAE papers - and now shown in the sim. Getting a balance between the blowdown needed to achieve the power you want, and the transfer area available is the tuning trick most valuable.


Superposition at ExPort opening is loosely referred to as pipe/port resonance, and is best achieved over the widest range with low Ex durations down at 192*. Unfortunately this is countered by needing a lot more blowdown than these numbers allow, and around 198 is needed to achieve the best bmep numbers. In this scenario we try to achieve resonance at peak and beyond, to give plenty of overev power.

Next issue that is my favorite hobby horse for today is Ex duct exit area. You will find a heap of free power, when using a T port or a Tripple port configuration, by limiting the duct exit area to around 75% of the Total Ex Port Effective.
Then make the header start at the area = to the Total Effective. Join these with an oval to round adapter in the spigot or flange, where the width = the header dia all the way thru, to enhance the flow from the blowdown area,and
the height at the flange face forms an oval to give the correct 75% area.

The Temp Av in the pipe should be around 500 as in any fast engine you would measure around 600 in the header.
The TuMax should be around 1000,any more and you get deto, alot less and it means the temp/pressure rise in the chamber isnt high enough, and you are restricting the "push" on the piston. But can also mean that you are using retarded timing to get heat into the pipe, not create pressure on the piston.

Lots more stuff, so little time.

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. 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 is to much.
Cheap insurance, cost $68 :- http://www.ebay.com/itm/Knock-gauge-...e9e926&vxp=mtr

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.

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 a lot of power.

[TZ350]

More gold on pipes.

The problem is that we have a fixed set of lengths in the pipe that can only develop a depression over a certain period in time, but the rpm is varying as we accelerate thru the powerband.The point of max depression moves in relation to BDC as the rpm varies.

We can bias the efficiency of the diffuser to act at the front side of the curve, by having the max ( widest area below atmospheric ) depression occur later within the pipe length, or we can design it to create then max power around peak, or we can design the pipe to operate better in the overev.



The max depression part of the equation is confined quite rigidly within the boundary's set by a 32% header and a 68% mid section, but the superposition resonance effect is governed by the port timing and the pipe tuned length, so is much more able to be "tuned" to a specific end effect.



Here is the same engine trace showing the before peak curve - notice no superposition at EPO, and early peak depression.



Then peak Hp - we have superposition and max depression around BDC.



Then in the overev - we have big superposition and late max depression.

This scenario generates the greatest peak power, and gives a long smooth roll off , of the power into the overev.
It possible to reverse the superposition position, but we will always be fighting the impossibility of stopping the natural movement of the peak depression event
due to the fixed pipe length.

We can change the depression curve shape with clever diffuser design, but it will always move from early to late in the cycle as the rpm changes upward.

What isn't possible is to move the rpm point at which the max depression is seen at, and not have the max depression happen earlier at lower rpm - then later at higher rpm.

The biggest and widest depression around BDC is seen at the tuned point of the rpm and the pipe length.

The max ( lowest pressure ratio ) point will always move with rpm due to the fixed position of the diffuser.

In answer to seeing the Ex port pressure ratio in EngMod2T ( I have the software pressure take off point set a 0 = at the cylinder wall ) yes ,you can see any trace after the run is finished at any of the rpm points. Go to Thermo Traces, tick Pressure Traces, load the file, pick the rpm then pick Pex. This gives you the pressure trace centred on BDC, even easier to see the differences.

Romeau - interesting that you say that you think a " narrow " pipe would work best with a scooter that allows the engine to be "in the power " all the time - yes this is true, and is why I believe a design that creates max power and then max overev would be the best.

I say that because if correctly designed the much stronger wave action within the pipe at high rpm, can be used to produce a lot more total power under the curve. But then you say the engine has 190* Ex, this will make it impossible to create anything like maximum power.

No engine can ever be anywhere near max output with that duration, but yes it can have superposition over a wider range than a higher Ex port can create - and this gives a very wide flat torque output , but it will never be a proper match to run with a "narrow " pipe design for max power output.

I see, thanks. I just have to make pipes for what people have and the market offers to them, unfortunately most of the engines I have to make the pipes are oversquare, low timing sometimes, weak transfer port areas or entrance angles, trash designed exhaust ports, bullshit cdi's with fixed timing or change just a little, very confused owners sometimes too. It's what I got :/

By the way, the rotax 122/123 engine that is used on the aprilia rs 125 have supposedly about 182/183º exhaust timing. (some other engines have stock timing like this ex. Banshe 350) In a case like this, will this engines take profit from any superposition with a timing relatively lower than 190º? Would the residual pressure wave that arrives too soon to synchronize with the new exit pulse at exhaust open, but still make any positive/noticeable effect? Thanks

The low Ex timing makes superposition able to be used over a much wider band of rpm.
In this case there is much more opportunity to design the pipe to adjust the powerband shape you want, as the tuned length resonates with the port over such a wide range.

The difference is tuning for breadth of power spread or tuning for ultimate power.

Bottom line here is that as I have stated many times the tuning regime for leaded is completely opposite to that of unleaded pump type gas. To get ANY benefit from a good leaded fuel they need to increase the com, back out the timing and run lean as hell. NFG at all without an egt.

Get some super well proven A747 to run with it at 20:1, but if they are so gun shy of the thing that they wont do the dyno time and do proper back to backs then its probably not going to be much use simply changing fuel and jack shit else.

1300 is too hot. Means that the ignition is ramping out too much timing past peak power.
But just as likely that the com is a bit low at 15:1. Try some more advance past peak, ie flat line it at say 10* ( depends upon what the peak power timing is - it should be around 15* ) then depending upon the result, chuck it some extra com up closer to 16:1. Both things will reduce the temp at high rpm , without having to go richer to stop it.

20:1 is fine for best engine protection. Only issue is that Elf 909 will settle out quite quickly in AvGas, but as we used to do in the old days with Castrol R just add a little Acetone and that problem goes away. I have not actually tried Motul Kart without the Acetone, so that may be OK in AvGas.
A747 is fine in AvGas.

Interesting read from Luc Foekema on spark energy and timing as posted on facebook:
https://www.facebook.com/notes/4223470164094/

Conclusion: More top power as shown in the graph [from decreasing spare energy to 50% from 11K rpm], indicates a not good combination of setup and the exhaust pipe. The setup is optimal for a higher rpm then the exhaust pipe is made for. Just to lower the spark energy, more heat will be available for the exhaust pipe, resulting in a higher rpm and in this case a higher power output.

Conclusion "when there is a gain in toppower by reducing spark energy, the temperature in the exhaust pipe is too low or the exhaust pipe is too long, otherwise a gain in toppower would be impossible".

Roller bearings can take higher loads, but that is not the main reason. When fitted correctly the Aprilia bearings allow for 0,4 mm of axial play. Any less costs power.
You can't do that with ball bearings (unless you use a sloppy fit on the shafts, like many kart tuners used to do).

976 is a full synthetic just like Motul 800,so is OK for unleaded fuel ( as they were designed for ) when run rich to prevent breaking down the oil when it overheats. I did hours of dyno oil testing for a customer using 909 and 976 in a KT100 to establish the best type and ratio.

As soon as you really wind in the needles the superior lubrication of the castor base made more power the hotter the egt got. The 976 started to show marks on the skirts and lost power over around 620* in the header.

i can see why someone would use a high B. allows the aux to be just that much bigger by bringing the floor down a little more. but some engines cant have the aux floor right on top of the A like aprillia because the side piston skirt is cut to high so the aux floor needs to be kept a little higher or you get a short circuit.

On a situation like this do you think the high B would still work better or is its only benefit to allow the aux floor to sit right on top of A ? basically what I am wondering is does a high B only have the benefit on letting the aux floor be very close to the top of A (assuming the piston design will allow it without creating a shortcut) or does a high B also have some kind of scavenging benefit also ?

No - the high B gives more total STA to the transfers, as in a well designed setup it is alot wider than any A port. So you have the B and C ports combining to give a better total STA than is possible with a normal small A and progressively lower B and C ports.

But its always a compromise, it makes no sense to run a high B port with no powervalve, as this scavenging regime favours top end at the expense of below pipe power. As I detailed before I could, and did, make a very good attempt at matching the high A port setup in a KZ2 with the big B port situation - but at the end of the day we needed the high A port to get natural drive off the bottom when passing in traffic.

But this was helped some by the factory catching up on the usual 3 year lag in technology when comparing GP125 with KZ2 and allowing me to grind really big Aux port top edges to gain sufficient blowdown to match the rocket ship big B port engine I did the year before.

rode the bike today and it pulls 1000 times better below the pipe than the last cylinder. probably because the ports are not sky high i suppose. mostly the transfers probably. before it seemed to have 1000 rpm wide powerband. below that and it could not recover without down shifting 1 or 2 gears. now it pulls back to the pipe alot better without down shifting ( in most situations). i left some meat on the bone so i can make more cylinder adjustments if needed. any body got ideas how to get more power without the midrange dropping out, like the last cylinder ?
here is what I got:-
honda T port exh and no powervalve
exh 192 and about 90% width
A trans 128 and 20* upward
B trans 127 and 15* upward. piston dome is 15* also
C 127 and 62* if I recall

I did the best I could with the upward angles. honda had them backwards. 20* on the rear and 15* on the front so I did the best I could with what i had to work with. i even lifted the cylinder up slightly with thicker gasket to try and correct the floor angles.

did not get the spacer installed under the reed stopper yet. should be able to get that done this week and tested next weekend. i think it will help as the current 7mm lift seems really small. still might not be enough lift with the spacer but at least I will know if I am going in the right direction

ive tried 200*. with 132 A and 130 B if i recall. worked ok. but i want to find a good compromise with lower ports. at some point i think the ports get so high you gain nothing but overrev which is useless for me. i ride in sand so there needs to be some power slightly lower in the rpm otherwise the sand can pull the rpm down too easily. maybe 8spd gearbox is the answer

You only need to fill in 3 pages of EngMod to get the full benefit of the STA readout page.
Just having the engine, Ex and transfer inputs will tell you where the ports are in relation to what you think you need.
You , and we, are simply guessing at what is happening until you can give us the STA printout. Do that and we can help.

But best throttle response is had with tons of advance at low rpm/WOT.
If you retard at low rpm/WOT the pipe may get hotter, but it will be very slow responding - due to the low cylinder filling and thus low dynamic com. You have to use so much advance down low it will instantly deto if you run it at part throttle down there. That is where the TPS is good in that you can pull out timing when at part throttle/low rpm,then add a heap when slamming it open to make it drive hard.

Welcome to the piston side.
Below you will find brands such as:
Barikit, Kitaco, Wiseco, Pro-X, Polini, Mahle and others.
I stocks normally pistons that you see below.
, there are other pistons in stock,
which can be a bit odd sizes etc..
If you can not find what you are looking for, write and ask,
so we'll see if I can help you!

Attachment 304145

http://www.pvlsverige.se/vrm/kolvar/kolvar.html

Rolffe is the Mad Swede who did the Debri cylindered MB50 with a disk valve.
What happened to the piston rod spreadsheet Brent was going to do.
this site is a great one in particular as it gives the oclock position of the ring pegs'.

[dark art]

The Aprilia RS123 as it has a powervalve is able to be tuned to a higher level over a shorter range than if the PV wasnt installed.

...

Here is the Arrow design, really dumb with incorrect header length etc, but it gives the result they intended.

First post here, so go easy on me

I had a aprilia rs 125 model (rotax 123 engine), 2003 model wich arrow pipe was quite different than yours. See below.
Dimentions might not be exact, they was only a rough measurement.

One of the worst things about that pipe was that the PV open sooner than the engine hit the power band, so there was a huge hole around 8-8500 rpm and that was with the cdi mod for the valve to open later. Was very annoying...
Later I mod the pipe on the header to make it slighty longer and that helped but was not perfect. I ended up building a new, longer pipe for the bike.

[dark art]

Anything special for page 1000 TZ ?

Free candys to everyone?

[chrisc]

Congrats! I found a photo of the original GP125 on the web.



I spent a considerable amount of time on the ESE thread today. I'm so stoked the resource is here. Thanks!

[Farmaken]

Wow Rob, it's like they say - from tiny acorns...
Seems you planted a seed and have grown a mighty fine resource with the help of some very fine minds
I for one am very grateful to be able to use so much of the information in this mighty collection, long may it continue

[TZ350]

Yes with the input from Wob and Frits and others it has become a great resource, we could not have got here without their help.

The old Suzuki GP125 is 12-15hp standard, pushed ours out to 31, so pretty happy. Even happier about the good friends we have meet along the way.

[chrisc]

Yes with the input from Wob and Frits and others it has become a great resource, we could not have got here without their help.

The old Suzuki GP125 is 12-15hp standard, pushed ours out to 31, so pretty happy. Even happier about the good friends we have meet along the way.

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



And I had a giggle at Darren inspecting the track conditions.

[husaberg]

NSR500 Porn
http://www.kiwibiker.co.nz/forums/al...p?albumid=4837
http://www.kiwibiker.co.nz/forums/al...p?albumid=4837

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

Aprilia GP bikes
http://www.kiwibiker.co.nz/forums/al...p?albumid=4839
http://www.kiwibiker.co.nz/forums/al...p?albumid=4839
YZR500

Swiss auto
http://www.kiwibiker.co.nz/forums/al...p?albumid=4833
http://www.kiwibiker.co.nz/forums/al...p?albumid=4833

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


RGV500

Kenny Roberts 3's

Cagiva
http://www.kiwibiker.co.nz/forums/al...p?albumid=4842
http://www.kiwibiker.co.nz/forums/al...p?albumid=4842

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

[andrew a]

Well done Rob and team. I called in last week but Rob was unfortunately out working. Cully showed me around. Great to see your shed. The ESE thread is a great sauce of information.

[speedpro]

Not so good on fish & chips though

[Frits Overmars]

NSR500 Porn
http://www.kiwibiker.co.nz/forums/al...p?albumid=4837

I will be adding some more later including
Honda RS125

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

Swiss auto
http://www.kiwibiker.co.nz/forums/al...p?albumid=4833

Husa, your links give me this:
vBulletin Message
Invalid Album specified. If you followed a valid link, please notify the administrator

[husaberg]

Husa, your links give me this:
vBulletin Message
Invalid Album specified. If you followed a valid link, please notify the administrator

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

[Muciek]

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

I'm too getting this notification

Invalid Album specified. If you followed a valid link, please notify the administrator