ESE's works engine tuner

[Chambers]

Gold Mine:- http://www.2stroke-tuning.nl/media/index.php?dir=artikelen/

And :- http://www.2stroke-tuning.nl/media/index.php?

Mostly in Dutch but you get the idea.

[bucketracer]

This may be of interest "How to Choose a Power Band" by Eric Gorr.

http://www.whidbeyparts.com/info/Howtochooseapowerband.pdf

.

[TZ350]

MSV Mean Squish Velocity Calculator:- http://myweb.tiscali.co.uk/teamsparrow/cylinderheadsv2_3.xls

.

[TZ350]

Bugatti

The engine is about 12.66cc, one cylinder, 2 overhead cams and a supercharger.

http://www.bugattirevue.com/revue29/t72.htm

The smallest Bugatti, measures only 12.66 cc. recently photographed in France, the one prototype built in 1944. Dimensions are 24 x 28, plus supercharger and gear driven overhead valve gear. It was capable of 10,000 RPM. The detail pictures below speak for themselves, really a very fine piece of engineering!

.

[bucketracer]

A page about moving heat:- http://www.koolance.com/technical/cooling101/002.html

After reading this I can see why TZ is using copper in his cooling system.

[TZ350]

.

A jpg file of a degree wheel that you can download and print out.

http://www.eurospares.com/graphics/degreew.jpg


And also from Euro Spares a "Bibliography of Technical Books."

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

.

[Chambers]

TZ I finaly got the gist of the SAE paper on crankcase volumes you refered me too.

Last paragraph page 175: The drop in delivery ratio caused by increasing the crankcase volume can be fairly well compensated for by tuning the inlet and exhaust system.

http://www.edj.net/2stroke/jennings/crankcase_volume.pdf

Second paragraph of the discusion section page 188: Small crankcase volume is best for high speed and large volume for low speed. Explanation: with small volume and low speed the crankcase discharges to fast into the cylinder and for the rest of the transfer-port-open period there is reverse flow.

Forth paragraph of the discusion section page 188: If the engine speed is selected to best suit the crankcase clearance volume the clearance volume does not effect the delivery ratio. Tuning either the inlet or exhaust pipe or both increases the delivery ratio.

So from reading the SAE paper, you have to have the right crank case volume for the intended engine rev's and it needs to be a smaller clearance volume ie., a higher primary compression ratio thats closer to 1.5:1 the higher the rev's.

.

[F5 Dave]

The Two-Stroke Shop
Stephen Rothwell and Wayne Wright (Wobbly)

www.twostrokeshop.com
Email: info@twostrokeshop.com


THE most advanced high-performance two-stroke motorcycle engine on the market today.

http://www.twostrokeshop.com/two_stroke_shop_engines.htm

Toroidal head and flat top piston.

.

Well that's stretching it to claim it is the most advanced 2 stroke on the market & bear in mind I own one (ok without the toroidal head). But the cylinders while light-years better than the original are compromised crankcases not being full crankcase reed induction & not having the room between the bores for sweeping transfer paths (despite going to a monoblock).

Seems to me the Toroidal head suits larger bores by positioning the plug closer to the action. The smaller the cylinder the less use it is likely to be, it is possible to get too close, I have seen good evidence of this. Obviously there is applications to fuel matching as Kirk points out.

[bucketracer]

Well that's stretching it to claim it is the most advanced 2 stroke on the market.

I guess even " www.twostrokeshop.com " can't resist a bit of "Sales Speek".

[F5 Dave]

I've spoken to Steve & he's a passionate guy, even before he started TSS. Nice guy & seems on the level.

[TZ350]

With 7 of 8 rounds done I am 6th in A grade. There are many better riders but my result is the fruits of consistency, having started/finished every race so far.

http://www.amcc.co.nz/results_bucket/0809ABUC.html

Last Sunday (round 7) was forecast to rain, although it remained fine for the races. I was still struggling to shake of the flu. I was feeling to ill to try competing but with a fast start and finishing the race. I figured I will pick up useful points.

So the plan became, use practice to experiment with the suspension, the pre-lim races to practice fast starts against the others as the starts are everything at Mt Wellington and for the points races to just relax back, take my time and experiment with powering on earlier in the corners.

Poor Chambers was not ready for the flag drop in the first points race and he made a flustered start, then he missed a gear into the first corner and this completely threw him and he pulled off in disgust.

So no points for him and enough points for me that its unlikely he will be able to better me on the point’s table this year.

I had been listening to Warrick and a couple of the other riders talking before practice and the conversation was about how the difference between a good days racing and a bad day was where they were at in their heads. Its certinly true for me.

The ESE bikes are consistently good, but little things can really throw you and it’s often just the morale of the rider that makes the difference on the day.

Nicholas and Daniel Lancaster on their CB125’s were really flying, as were Tim and Rick, they were having a very good day. Steve on his new 2-stroke was going well and looking smooth untill a gremlin got into the motor.

At the end of racing I was pleased to get off home as I was away to Dunedin Monday morning and the forcast was for hail storms and snow, just great, as I was going to be working outside on the coast for the next few days.

The good part was, Eileen was with me and we got to stay at a wonderful B&B that did evening meals. It was run by a chef and his wife, the house was built in 1865, http://www.lisburnhouse.co.nz/ it had a big log fire and the food :laugh: was just out of this world.

.

[TZ350]

Tomas gets back to working on porting the GP125 cylinder.

Pic-1 He bends a wire template to the curve of the transfer port.

Pic-2 Tomas and Alexi heat and bend some rifler files to the shape they want.

Pic-3 Using the wire template to judge the amount of bend needed.

Pic-4 Re-Hardening the file by dunking it in an oil bath.

There is special oil for this but just about any oil will do. If you use water the file will be to hard and brittle.

Pic-5 Some of the modified files.

Pic-6 Tomas finds his new files work well.

.

[TZ350]

Tomas explained to me, how the surface finish of the ports should be. This is what I remember of what he told me.

Pic-1 Tomas said that if fine file marks are made across the direction of air flow then small air vortices develop and these act like ball bearings and the air mass slides easily over them.

Pic-2 He says its easy to get a polishing mop and go mad mirror polishing the port, curve (1) but you often wind up with a ripply surface and this is bad.

He says it's much better to have a smooth contour, curve (2) even if that means a rougher surface finish like you get with a fine file.

It used to be all the rage to polish the ports but with a mirror polish in the port, the air boundry layer that clings to the port wall is quite thick and moves like treacle.

But a surface finish that promotes micro vortices that act like small ball bearings reduces the boundry layer too next to nothing and the air mass's resistance to flowing along the port is greatly reduced.

Tomas says a smooth polished surface that has been sand blasted is best and a fine file or sandpaper finish that cuts across the air flow is also very good but file or sand paper marks that go in the direction of air flow don't help much.

.

[F5 Dave]

While we're on it (not easy for transfers mind); Small rotary carbide bits seem to work ok but are very good at leaving ripples, large flame type ones are much better but need a grunty Bosh(sp) or air powered with decent compressor to drive. Decent Stone bits take out irregularities leaving a flat surface with a honed appearance, mighty fine.

[Fooman]

It used to be all the rage to polish the ports but with a mirror polish in the port, the air boundry layer that clings to the port wall is quite thick and moves like treacle.

But a surface finish that promotes micro vortices that act like small ball bearings reduces the boundry layer too next to nothing and the air mass's resistance to flowing along the port is greatly reduced.


As a point of information, this is why golf balls are dimpled, rather than smooth - less drag, so they go further.

A quick check of my old fluids text (Massey, Mechanics of Fluids 6th Ed.) says the (thin) turbulent boundary layer promoted by the rough surface delays separation of the flow, reducing the drag caused by the gross separation (turbulence) of the flow across the surface.

I feel old. That textbook is 20 years old now...

Cheers,
FM

[Skunk]

That textbook is 20 years old now...
And people STILL insist on have polished ports and stuff...

[bucketracer]

Decent Stone bits take out irregularities leaving a flat surface with a honed appearance, mighty fine.

The good thing about stone and resin bits is that they can be re-shaped by running them up in a hand drill and working them against the side of a spining stone wheel in a bench grinder.

.

[F5 Dave]

Good tip I haven’t tried that, usually most of the stones I run on the smaller Dremel or the air grinder are flame shaped which seems most useful.

CRC will help keep carbide tips from clogging, but a wire brush every so often is par for the course to keep cutting clean & smooth. Good sealing Eye protection is so important.

[TZ350]

It might be Karts, but there is a bit of interesting reading here.

www.kartweb.com/TechArt/2Stroke/chapter1.doc

www.kartweb.com/TechArt/2Stroke/chapter2.doc

www.kartweb.com/TechArt/2Stroke/chapter3.doc

chapter 3 is on chambers.

.

[TZ350]

.

Someone else's efforts at porting:- http://www.teamsmoke.com/photo4.html

Lots of pictures, I particularly like the tool he made for measuring the transfer port opening height's.

He also made a real trick tool for holding the tip of a round file at just the right angle for the transfer port roofs.

.

[TerraRoot]

"If you layed all the 2 stroke tuners end to end they still wouldn't reach a conclusion"

that cracked me up :lol:

[koba]

"If you layed all the 2 stroke tuners end to end they still wouldn't reach a conclusion"

that cracked me up :lol:

Yet another case of funny AND true!

So TZ, any plans in the works for taupo?

[TZ350]

Yet another case of funny AND true!

So TZ, any plans in the works for taupo?

Yep funny and Oooo so true.

Signed up for Taupo, F4 & F5. Will we see you there?

.

[koba]

Yep funny and Oooo so true.

Signed up for Taupo, F4 & F5. Will we see you there?

.

Will be there on somthing, I would like to have a bucket sorted for it but its looking like a steep hill from here. May give F3 a crack.

[quallman1234]

May give F3 a crack.

Might see you there ;). Give you the learn on the 125 :lol:.

BTW ; I sorted out a very temporary rear end for my bucket. Focus on other things, for now. Then ill get back too it. Pioritising! (sp?)

[TZ350]

I went looking for Thomas today to see if he could shed some more light on crankshafts and balance factors.

I found him working on a classic V12 Lamborghini Miuras. The engine has just been pulled out. And yes that is four tripple throat Webbers on there.

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

From Wikapedia

Early P400 Miuras, known as P400s (for Posteriore 4 litri), were powered by a version of the 3.9 L Lamborghini V12 engine used in the 400GT at the time, only mounted transversely and producing 350 PS (345 hp/257 kW). About 275 P400s were produced between 1966 and 1969 - a success for Lamborghini despite its then-steep $20,000 USD price (approx. $114,000 in today's terms).

Taking a cue from the Mini, Lamborghini formed the engine and gearbox in one casting and they shared common lubrication until the last 96 SVs, which used a limited slip differential requiring appropriate oil.
...........................................

Thomas said you can make balancing crankshafts as hard or as easy as you want it to be. You can get lost in the maths and science of it or just approach it in a practical way.

Although a single cylinder crankshaft is the hardest to get in balance but on the bright side its the easiest to work with.

He said, if he gets a chance he will explain an easy way to calculate a balance factor and also draw some pictures of a practical way to balance a single cylinder crankshaft.

He also reminded me that the engine reacts with the frame and that a balance factor that works on one bike might not work well with a different bikes frame.

Also tuning can affect vibration, poor midrange tuning can make an engine pop and bang about shaking the bike and also vibrations from the engine can send the suspension springs into a dither through sympathetic harmonic vibration.

He thinks the difference between SS90's 25% and the higher balance factors others are talking about could just be in the definition of terms.

Thomas also remarked that SS90 cut his crank to give himself more crankcase volume, the experiment was primary compresion ratio not balance factor. Thomas also said that he has seen other bikes like the RM400 with a "pork chop" crankshaft like SS90's.

First three pics are net-scrapes.
.

[Yow Ling]

that will be a tricky one to copy

[speedpro]

What Thomas says . . getting bogged in maths and science on a single cylinder crank is silly. Suck it and see is way easier. I have also found that frame mods affect how much vibration you get. sometimes it's better to tie the engine in good as it increases the mass and doesn't allow the vibration to build resonance for example.

On the other hand if you were building a narrow angle V6 2-stroke without a balance shaft then science has a place determining firing orders, crank phasing, and a few other things.

[Buckets4Me]

I want to know what Thomas is thinking

has he made an application to get the 4stroke limit pushed out to 4000cc ????

and how is anyone going to get past that slug anyway (or is that the plan firt to the first corner and let anyone try and get past)

do tell him that that engine will not fit in my rs frame (but we could make a really nice sidecar with it)
:drool:

[TZ350]

Here is a real practical way to balance an inline four cylinder engine or any engine probably. Not your conventional approch but I bet it works in its own way.

http://www.vibrationfree.co.uk/engine%20balancing%20ppc.pdf


UTUBE vid of a crank with bob-weights being dynamicaly balanced. The bob-weights represent the balance factor chosen for this crank, or in other words how much (balance factor in %) of the reciprocating mass (piston assembly and top half of the rod) that is going to be counter balanced by the crank webs.


http://www.youtube.com/watch?v=cxWp2J1WG0A&feature=PlayList&p=0C73475A127D847B&playnext=1&playnext_from=PL&index=5
.

[F5 Dave]

Well I have seen a bike with an off center weight bolted to the flywheel. Can't help but think that was a bit rough as 70mm from the vibration plane, but I guess may help experiment.

[TZ350]

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving.

http://www.scribd.com/doc/15392252/Tuning-for-Speed-P-E-Irving-1965-Tuning-Racing-Motorcycle-Engines

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

Thomas says it's all you need for working on a single cylinder crank and also Speedpro is right, it's very much "suck it and see".

.

[TZ350]

Well I have seen a bike with an off center weight bolted to the flywheel. Can't help but think that was a bit rough as 70mm from the vibration plane, but I guess may help experiment.

I have finaly got my head around what F5 is saying. He's right, its a rough way of doing it but probably a very quick and effective way of determining whats needed.

.

[Skunk]

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving.

http://www.scribd.com/doc/15392252/Tuning-for-Speed-P-E-Irving-1965-Tuning-Racing-Motorcycle-Engines

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

Thomas says it's all you need for working on a single cylinder crank and also Speedpro is right, it's very much "suck it and see".

.
Downloading it now. Cheers.

[FastFred]

Yes thanks TZ and Thomas, thanks for the link.

[xwhatsit]

Lol -- here I am scratching my head trying to work out what will happen when I add a 350 piston onto a 250 single (with balancer shafts, no less) -- and I'm the guy who uploaded Tuning for Speed to Scribd in the first place :laugh:

Came out before balancer shafts though... but still useful theory.

[TZ350]

Thanks for doing that xwhatsit.

[sonic_v]

Here is an online Squish Velocity Programme. There is also a few other useful programmes.

http://www.torqsoft.net/squish-velocity.html

http://www.torqsoft.net/piston-position.html

[FastFred]

Good Stuff, thanks SonicV, had a play with them, very usefull.

[TZ350]

Links.

Terminolagy:- http://www.2-stroke-porting.com/terminology.htm

MSV Mean Squish Velocity Calculator:- http://myweb.tiscali.co.uk/teamsparrow/cylinderheadsv2_3.xls

Simulation video clips of 2-stroke scavenging:-
http://video.google.com/videosearch?client=firefox-a&rls=org.mozilla:en-GB:official&channel=s&hl=en&q=two+stroke+scavenging&um=1&ie=UTF-8&ei=-EUFSunlCcjJtgeG2K2XBw&sa=X&oi=video_result_group&resnum=4&ct=title#

A catalog search engine, pistons, rod kits etc.
http://www.who-sells-it.com/r/mahle-pistons-2-stroke.html

Using only one ring:- http://www.vintagesleds.com/library/manuals/misc/jennings/l-ring_effect.pdf

The effects of higher compression ratios in a 2-stroke:-
http://www.vintagesleds.com/library/manuals/misc/jennings/higher_compression.pdf

From, Yow Ling. www.zeeltronic.com has fully programmable cdi's about 100 euros.

Stan Stevens RGV Tuning:- http://www.stanstephens.com/rgv.htm.

A MacDizzy Blaster Engine Rebuild with Photos:- http://www.macdizzy.com/1989hhopup.htm

MacDizzy's:- http://www.macdizzy.com/

Modifying a Suzuki open chamber to a squish head:- http://www.ozebook.com/compendium/t500_files/morgan/head.htm

Dispelling 2-stroke tuning myths:- www.fatbaq.com/RS125_dispellingmyths.doc

Gordon Jennings:- http://www.vintagesleds.com/library/manuals/misc/Two-stroke%20Tuner%27s%20Handbook.pdf

An assortment of Gennings Articles:- http://www.edj.net/2stroke/jennings

Graham Bell:- http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf

Yamaha SAE Paper on Porting:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

Gold Mine 1:- http://www.2stroke-tuning.nl/media/

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving.

http://www.scribd.com/doc/15392252/Tuning-for-Speed-P-E-Irving-1965-Tuning-Racing-Motorcycle-Engines

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

Rate of Fuel Burn:- http://www.factorypro.com/tech_tuning_procedures/tuning_fuel_octane_vs_power.html

Reading Plugs:- http://www.dragstuff.com/techarticles/reading-spark-plugs.html

Engine formulas:- http://members.bellatlantic.net/~vze2p5sj/modelengines/engine1.htm

A Handy Coverter:- http://www.mr2ownersclub.com/converter.htm

Detonation:- http://www.factorypipe.com/t_deto.php

Dale Alexander. The Art Of Squishing Things Until They Make Power:-
http://www.aircooled-rd.com/default.asp?txtPage=squish1.htm
http://www.aircooled-rd.com/default.asp?txtPage=squish2.htm
http://www.aircooled-rd.com/default.asp?txtPage=squish3.htm

A preview of Kevin Camerons book “Sportbike Performance Handbook”:-
http://books.google.co.nz/books?id=LswdRd2Zm8YC&pg=PA85&lpg=PA85&dq=tz250+detonation+repair&source=bl&ots=zYYDz0MEyv&sig=pRPBbN00SOAg-wfME3O1YZCk9KU&hl=en&ei=Ve2tSb6iBYT06QO585zgBQ&sa=X&oi=book_result&resnum=1&ct=result#PPA81,M1

TUNING VESPA'S THE NORRIE KERR WAY.....
http://www.scooterhelp.com/serial/tuning.books.html

Crankcase delivery ratios and inlet timing for rotary disk motors:-
http://www.edj.net/2stroke/jennings/delivery_ratio.pdf

The effects of crankcase volume on the delivery ratio:-
http://www.edj.net/2stroke/jennings/crankcase_volume.pdf

Piston pin offset and what it means for extra power:-
http://www.motorcycleproject.com/motorcycle/text/cows-offset.html

4-Stroke stuff but very interesting about porting and combustion.
http://www.gofastnews.com/board/technical-articles/

Supercharged Honda 50 http://www.elsberg-tuning.dk/the%20bikes.html

Drop your engine in liquid nitrogen:- http://www.iwt.com.au/cryogenics.htm includes dyno charts to prove the theory. Thanks Yow Ling.

The Big Tuning Manual from Piper Cams:- http://www.bgideas.demon.co.uk/tmanual/ it talks about combustion chamber shape and swirl patterns, and are PDF's that can be down loaded.

.

[TZ350]

Here is an online Squish Velocity Programme. There is also a few other useful programmes.

http://www.torqsoft.net/squish-velocity.html

http://www.torqsoft.net/piston-position.html

SonicV would you mind if I add you'er links to my list?

.

[F5 Dave]

I had a bit of a quick squizzy at The effects of crankcase volume on the delivery ratio:-
http://www.edj.net/2stroke/jennings/...ase_volume.pdf (The effects of crankcase volume on the delivery ratio:- http://www.edj.net/2stroke/jennings/...ase_volume.pdf) & must admit I'd never heard of the test engines. Then noticed they spin out to the dizzy heights of 4500rpm at best. One can imagine that the pressures involved are not proportional compared to time areas due to gas flow at up to 3x the revs.

ok here's one to send people down the garden path with a nice but difficult idea
http://www.muller.net/mullermachine/docs/slippy1.html

Borut makes Zeeltronics stuff for mainly RGV, NSR etc but could be possible to adapt to a bucket but you'd have to talk to him, you need 3 boxes to get programmable & will cost a site more than 100 euro. (I have a setup on my 500).

[Yow Ling]

IBorut makes Zeeltronics stuff for mainly RGV, NSR etc but could be possible to adapt to a bucket but you'd have to talk to him, you need 3 boxes to get programmable & will cost a site more than 100 euro. (I have a setup on my 500).

I have a Zeeltronics ignition controller on my lc, it works with the stock cdi because there is no curve in the lcs cdi. Rzs need a zeeltronics cdi to replace the yamaha one to get rid of the stock curve. i think thr controller was 100 euro and the programmer 50euros. the third box is the powervalve box ?

he also has a 12v cdi so you dont need exciter windings on your stator and want to run total loss

[Skunk]

Wow, I knew if I waited long enough some more info I can use would be forthcoming (rather than questions), but I never expected that bonanza!

[sonic_v]

SonicV would you mind if I add you links to my list?

.


Fire ahead

[F5 Dave]

I have a Zeeltronics ignition controller on my lc, it works with the stock cdi because there is no curve in the lcs cdi. Rzs need a zeeltronics cdi to replace the yamaha one to get rid of the stock curve. i think thr controller was 100 euro and the programmer 50euros. the third box is the powervalve box ?

he also has a 12v cdi so you dont need exciter windings on your stator and want to run total loss

Yeah but it means you have to have a battery at the least. If your cdi was straight curve then you don't need the 3rd (CDI) box (4th is powervalve if you call then programmer a box).

[TZ350]

There is a bit of a spat going on, on the two stroke tuners thread over this question and no one will chance their arm.

Which is heavier, (A) the reciprocating weight of the rod piston assembly or (B) the counter weight of the crankshaft.

This is a test (A) or (B).

The answer is (A) as the counter weight only counters a % of the reciprocating weight and is lighter than the reciprocating portion of the rod/piston assembly.

.

[TZ350]

.

There has been a bit of talk about Crank Shaft Balance Factors on the Two Stroke Tuners thread, resulting in more heat than light. As there is a bit of a rowdy crowd over there I am going to make my posts here.

I intend to keep it simple, so for what its worth, this is our interpritation of Phill Irvings work.

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

http://www.scribd.com/doc/15392252/Tuning-for-Speed-P-E-Irving-1965-Tuning-Racing-Motorcycle-Engines

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving.

"xwhatsit" is the guy who uploaded Tuning for Speed to Scribd in the first place, thanks xwhatsit.


I will use a 2-Stroke single cylinder TF100 crank to demonstrate my explanations and I need to break it down into sections as I can't cover it all in one or two posts. Thomas gave me a hand, taking the photos and gave me a few tips along the way.


My plan is to:-

(1) Post photos of all the cranks I have lying around and quickly describe the features I can see on them.

(2) Describe how to find the reciprocating weight.

(3) What the "Balance Factor" really is.

(4) I will answer this question, Which is heavier, (A) the reciprocating weight of the rod piston assembly or (B) the counter weight of the crankshaft.

(5) Why there is a "Balance Factor" and what changing it does.

(6) What to do with your "Balance Factor"

(7) A simple but very effective jig for staticaly balancing a crank, that you can make yourself in 10min's. (Thanks Thomas)

(8) What a rocking couple is, and how the term is used in crank shaft balancing.

(9) Just for Skunk, Some of the problems associated with balancing a V2 90 degree twin with one horizontal cylinder.


This is going to be a very simple "KISS" look at single cylinder crankshaft balancing, based on Phill Irvings book. If anyone thinks I've missed something or wants a more in-depth treatment they are welcome to explore the internet for what they can find. Or dust of data from their own experiments and post it themselves. Then we can all enjoy reading their interpretation of what they have learnt.

.

[Skunk]

Thank you - I need edjacukating, and the two stroke tuning thread has really lost it in egos. Thank you Rob for taking the time to post information.

(9) Just for Skunk, Some of the problems associated with balancing a V2 90 degree twin with one horozontal cylinder.
I'm doing a 90° firing RD400 though...

[ajturbo]

this is a thread i am interested in!!...

[TZ350]

These Posts started, Page 70, 17th June.

(1) Post photos of all the cranks I have lying around and quickly discribe the features I can see on them.

Pic-1 Yamaha RD400 with lead balance weight.

Pic-2 Yamaha RD400 without lead balance weight.

Pic-3 Suzuki T500 with asymmetrical balance holes which means the counterweight is not directly opposite the big-end.

Pic-4 Yamaha RX125 with hollows forged/cast into the flywheels.

Pic-5 Suzuki RG50 which clearly shows the counterweight portion of the flywheel.

When the flywheel is drilled the counterweight part is not as obvious as in the RG50 (pic-5) you just have to imagine its there.

.

[TZ350]

These Posts started, Page 70, 17th June.

(1) Post photos of all the cranks I have lying around and quickly discribe the features I can see on them.

Pic-1 Suzuki GP125, hard to see but the front hole is a little smaller than the rear one.

Pic-2 80's Suzuki RM125

Pic-3 90's Suzuki RM125

Pic-4 Yamaha KT100 Kart

Pic-5 92 (I think) Honda RS125

Pic-6 Honda MB100 and is what I think the RS crank would look like with the tin covers off.

.

[F5 Dave]

how on earth are you typing all this? One handed? My posts got very brief for a month.

In Skunk's case he doesn't want a Vtwin with a horizontal cylinder, but a parrallel twin 270 deg TRX style.

[TZ350]

Just had a PM from Skunk, Interesting project.

I am lucky, my right hand is OK, and I have all day.

.

[ajturbo]

and AJ just wants the RG50 to go a little bit faster.... but stay reliable

and for the GT to friggin FIRE

[F5 Dave]

and AJ just wants the RG50 to go a little bit faster.... but stay reliable


Lose weight. Turn throttle to open position, keep there, don't back off unless you really need to & even then count to 4 before doing so & only for a second:yes:


. . .
and for the GT to friggin FIRE

Set alight.

[Sketchy_Racer]

Lose weight. Turn throttle to open position, keep there, don't back off unless you really need to & even then count to 4 before doing so & only for a second:yes:

Set alight.

Haha good advice Dave..

Your up late, baby keeping you up?

[sonic_v]

One of the first port of calls should be to reduce reciprocating mass. If there are limited piston kit options for a particular engine and the gudgeon pin is of the parallel wall type, I like to obtain a tapered wall gudgeon pin from a different engine. In the worst case scenario you may have to shorten the pin slightly.

It is surprising how much mass can be saved with a tapered pin. I have found suzuki motocross engines to be a good source of gudgeon pins.

[ajturbo]

Lose weight. Turn throttle to open position, keep there, don't back off unless you really need to & even then count to 4 before doing so & only for a second:yes:



Set alight.

:Punk:the 4 second rule.... that's where i have been going wrong.... all these years i thought it was 2 seconds...:scooter:




:bash::bash::bash::bash::bash::bash::bash:

[k14]

Lose weight. Turn throttle to open position, keep there, don't back off unless you really need to & even then count to 4 before doing so & only for a second:yes:
Yeah but then you end up with a broken wing, not very good advice dave :bash:

[ajturbo]

Yeah but then you end up with a broken wing, not very good advice dave :bash:
ALSO.. i have NEVER heard HIM count!!!

[TZ350]

.

Personaly, I close my eyes. :pinch:

.

[TZ350]

These Posts started on Page 70, 17th June.

(1) Post photos of all the cranks I have lying around and quickly discribe the features I can see on them.

TF100 crank on the left 80's RM125 on the right. I've heard that the TF cranks vibrate real bad when rev'ed and that Speedpro fixed his by plugging the big hole with aluminum.

I have noticed that the TF is a-symmetrical and the motocross cranks are symmetrical (even sizes). The small hole on the TF crank could be opened up to, more like the RM and then plugged if you wanted to go to the extra work.

.

[F5 Dave]

One of the first port of calls should be to reduce reciprocating mass. If there are limited piston kit options for a particular engine and the gudgeon pin is of the parallel wall type, I like to obtain a tapered wall gudgeon pin from a different engine. In the worst case scenario you may have to shorten the pin slightly.

It is surprising how much mass can be saved with a tapered pin. I have found suzuki motocross engines to be a good source of gudgeon pins.

Interesting advice with the tapered pin. But also grey area from the rules. Pistons are free. So are the gungeon pins? hmm.

[F5 Dave]

Haha good advice Dave..

Your up late, baby keeping you up?
Yeah a bit, but mainly self inflicted.

[Skunk]

TF100 crank on the left 80's RM125 on the right. I've heard that the TF cranks vibrate real bad when rev'ed and that Speedpro fixed his by plugging the big hole with aluminum.

Interesting as my TF125 doesn't seem too bad even when I 'over rev' it (9000+ I guess). Until I get the RM80 flywheel on it I don't really want to be revving that high.

Anyone got a RM80 CDI?

[TZ350]

Interesting as my TF125 doesn't seem too bad even when I 'over rev' it (9000+ I guess). Until I get the RM80 flywheel on it I don't really want to be revving that high.

Anyone got a RM80 CDI?


That is interesting, wonder what frames the vibratey ones were fitted to? What frame do/did you have your TF engine in Skunk?

.

[Skunk]

It's in my AX100. Had it's first run last weekend. I've mounted it by all three points. There's a reasonable pic of the frame here (http://www.kiwibiker.co.nz/forums/album.php?albumid=57&pictureid=26313) with the engine in it.

[F5 Dave]

Interesting as my TF125 doesn't seem too bad even when I 'over rev' it (9000+ I guess). Until I get the RM80 flywheel on it I don't really want to be revving that high.

Anyone got a RM80 CDI?

Maybe. There is one year RM that reputably revs better than all others. I have never gotten around to trying it.

[TZ350]

.

Are you talking crank or ignition F5? do you know what Year?

.

[TZ350]

It's in my AX100. Had it's first run last weekend. I've mounted it by all three points. There's a reasonable pic of the frame here (http://www.kiwibiker.co.nz/forums/album.php?albumid=57&pictureid=26313) with the engine in it.

I asked because this is what Phill Irving has to say:- " p110 when adapting engines for use in 500cc racing cars, because the different method of mounting as compared to a motorcycle very often leads to trouble in obtaining smooth running.

and p107 it is quite useless to postulate any particular balance factor as being ideal; so many considerations enter into the matter that it varies with almost every design of engine, or even the type of frame in which engines of the same kind are mounted."


So your TF125 and AX100 frame combined OK, where other types of TF Engine/Frame combo hav'nt.


Good looking pic of you at Slipway, Skunk.


.

[F5 Dave]

sorry it was one year the RM used the flatslide 26.
83-85 for ignitions

[TZ350]

These Posts started 17th June on Page 70.

(2) Describe how to find the reciprocating weight.

Looking at the connecting rod it is easy to see that the Big End goes round and round and is all rotating mass. And the little end goes up and down and is all reciprocating mass.

But the bit in the middle is not completely either, it does a sort of wiggley motion. You can worry your self to death over it or just take a good old practical common sense approach.

Pic-1 shows the crankshaft divided into "Rotating Mass" on the left and "Reciprocating Mass (weight)" on the right.

Pic-2 shows the Reciprocating Mass (B) being weighed. When weighing its important that the conrod is level and only the little end touches the scales.

Pic-3 On these cranks its easy to see the counterbalance’s but in others you just have to imagine where they are as the can't be distinguished from the rotating mass.

The Rotating Mass within (A) naturally balances itself and is not involved in the crankshaft balancing process.

External items like Magneto Rotors, Generator Flywheels and in Cars Harmonic Ballancers/Flywheels/Clutches are fitted and ballanced after the crankshaft itself has been balanced. The crank is balanced first then the other round bits are fitted and balanced later.

In balancing the crankshaft there is only "Reciprocating Mass", "Counter Balance" and the "Balance Factor" which is the relationship between them.


Let:- "Counter Balance" = A "Reciprocating Mass" = B and "Balance Factor" = C

Then A = B X C .............now this is a real formula complete with a definition of terms.

This formula gives you the Mass (weight) of the Counter Balance if you know the Reciprocating Mass and the Balance Factor you want to use.

This is not new, Speedpro has allready posted hand drawn pictures like this, showing how he did it.
.

[Buckets4Me]

how on earth are you typing all this? One handed? My posts got very brief for a month.

.

he only uses two fingers :yes:
so now he is down to just one

[TZ350]

he only uses two fingers :yes:
so now he is down to just one

Any more cheek and I will stick my finger in your ear. :chase:

.

[ajturbo]

.

Personaly, I close my eyes. :pinch:

.
tried that with darts.....ONCE.... not allowed back in that bar any more...


but this is a great thread..thanks!

[Spyke]

I'm quite keen on any info on rg50 tuning. I have a 1978 gt50 (cafe project) which I'm trying to tune but keep reliable for road use any starting points?
Does anyone know the difference between the two, other than ones 5 speed and the others a 6 speed?

Oh and if any one has spare rg50 forks and front brake caliper assembly I'd be keen to talk.

[Skunk]

So your TF125 and AX100 frame combined OK, where other types of TF Engine/Frame combo hav'ntWe did run the bike with the front mount loose. It had a bolt but only finger tight. One minute and I think your thumbs would be numb from vibration. Do the bolt up tight and all is well.

76° works for Vee twins due to the Vee angles. 90° works for parallel twins. I guess it's all part of 'the angle of the cylinder affects the balance factor that works best' though the maths of it is beyond me.
I can tell that as a Vee the forces on the crank are quite different to a parallel of the same firing duration just by looking at it.

[TZ350]

I'm quite keen on any info on rg50 tuning. I have a 1978 gt50 (cafe project) which I'm trying to tune but keep reliable for road use any starting points?
Does anyone know the difference between the two, other than ones 5 speed and the others a 6 speed?

Oh and if any one has spare rg50 forks and front brake caliper assembly I'd be keen to talk.

We have found that the thinner GP125 forks fit in the RG's triple clamps. Then you can use the caliper, disk wheel etc.

We also have found that its possible to fit the early 2.15X17F 2.5X17R TZR wheels with very little effort. PM me if you want details. A little bit of milling on the side of the wheels, a little turning of the sprocket carrior and filing of the axle slots in the swing arm is about it.

Engine mods, well F5 has the fastest one around that I know of. Pete Sales???? I think, is the guru if you have a few $$$ to spend.

Good luck, I hope to have one going myself for Taupo.

.

[speedpro]

Pic-1 shows the crankshaft divided into "Rotating Mass" on the left and "Reciprocating Mass (weight)" on the right.

Pic-2 shows the Reciprocating Mass (B) being weighed.

That is exactly how I did it.

[ajturbo]

We also have found that its possible to fit the early 2.15X17F 2.5X17R TZR wheels with very little effort. PM me if you want details. A little bit of milling on the side of the wheels, a little turning of the sprocket carrior and filing of the axle slots in the swing arm is about it.

Engine mods, well F5 has the fastest one around that I know of. Pete Sales???? I think, is the guru if you have a few $$$ to spend.

Good luck, I hope to have one going myself for Taupo.

.


stuff the PM stuff... i think there are a couple of us that would like to know....:Punk:

[TZ350]

We did run the bike with the front mount loose. It had a bolt but only finger tight. One minute and I think your thumbs would be numb from vibration. Do the bolt up tight and all is well.

Sort of supports Phill Irving suggestion, different mounts, different reactions.


76° works for Vee twins due to the Vee angles. 90° works for parallel twins. I guess it's all part of 'the angle of the cylinder affects the balance factor that works best' though the maths of it is beyond me.

I can tell that as a Vee the forces on the crank are quite different to a parallel of the same firing duration just by looking at it.

Sorry I put you crook with the 76 thing.

.

[TZ350]

stuff the PM stuff... i think there are a couple of us that would like to know....:Punk:

I have only worked on the frame and wheels so far, no engine modes yet. I will take some photos to post Monday when I can get to work, every thing is over there.

.

[TZ350]

These crankshaft Balancing Posts started 17th June on Page 70.

(3) What the "Balance Factor" really is.


The "Balance Factor" 45%.....50%.......60%.........85% is the portion of the "Reciprocating Mass" that is balanced by the "Counter Balance" portion of the crankshaft.

Increasing the Balance Factor increases the size (Mass) of the Counter Balance. But the Mass of the Counter Balance is always less than the weight of the Reciprocating Mass.

Here is the Balance Factor relationship defined by an equation

A = B X C ........... Counter Balance-(A) = Reciprocating Mass-(B) X Balance Factor-(C)



The counter weight only counters a % of the reciprocating weight and is lighter than the reciprocating portion of the rod/piston assembly.

As an example, a balance factor of 65% means that the counter-weight portion of the crankshaft counter weighs only 65% of the reciprocating mass of the rod/piston assembly.

The Balance Factor could be anything, 25% 48% 50..............65%......85% whatever you chose/works for that engine/frame/rev's/and everything else combo.

The counter weight portion of the crank may or may-not necessarily be dead opposite the bigend.



The Counter Balance reduces the up and down shake but increases the sideways shake. I am going to try and explain the reciprocating-mass / counter-balance / balance-factor relationship visualy using vectors.

Pic-1 The Reciprocating Mass shakes every thing up and down. And the Counter Balance shakes everything backwards and forwards. The more, the up and down shake is reduced by the Counter Balance the more the sideways back and forth shake increases.

Pic-2 Shows the Reciprocating Mass as a vector pointing up and the Counter Balance as a vector pointing across. The result of these two vector forces is the Resultant force (Z) pointing up and across at 45 degrees in Pic-2.

Pic-3 As the Balance Factor increases 45%.....50%.......60%.......... The heavier the Counter Balance becomes. And the up and down shake is reduced but the sideways back and forth shake increases. In Pic-3 you can see the up/down vector reducing and the sideways back/forward vector increasing and the resultant tipping to the right as the Balance Factor is increased.



From this I am hoping you can see that all this shaking about can be aimed and how the motor pushes and pulls against the frame can be changed.

The Balance Factor is a compromise, chose your balance factor, guess if you have to, and if it shakes the frame to much, you can change the Balance Factor to change the angle that the motor reacts with the frame.

Interestingly Phill Irving suggests a balance factor of 66% as a good place to start and the 2009 Kawasaki KX250F and KX450F (4-Stroke) Motocrossers both have Balance factors of 60%.

2009 KX250F, Engine Displacement: 249cc, Max Horsepower: 32.8 HP @ 12,200 rpm, Max Torque: 17.2 lb-ft @ 8400 rpm.

I have no real information to back this up but I think fast 2-strokes could be 50%......60%, Hard data or opinion backed by references would be welcome.



If you have a real social problem and don't get out much you can work out the magnitude of the Resultant (Z) using Vector Arithmetic.

.

[quallman1234]

I ran my TF engine with only two mounts as i didn't have a bolt for the thrid yet, didn't vibrate too badly, but not exactly good.

[TZ350]

Thanks quallman1234

On the TF crank that Team ESE is working on I was all for banging in a couple of alloy plugs like Speedpro did. Also Yow Ling was having problems with vibration in his TF. But I hear that Skunk has not had a problem with his TF in an AX frame and now I can't help wondering what sort of frame Speedpro was using.

Reminds me of Phill Irvings comments on page 107 " It is quite useless to postulate any particular balance factor as being the ideal; so many considerations enter into the matter.............................do not be misled into rebalancing your engine just because one of your pals with an entirly different machine thinks he has some magic formula"

Nearly tripped myself up, saved by Skunks post, :sweatdrop must talk to Speedpro and find out more about why he did it, first.

.

[Skunk]

Sorry I put you crook with the 76 thing.
You didn't put me crook - you made me think about it instead of taking someone's word for it. Always good.

[F5 Dave]

I'm quite keen on any info on rg50 tuning. I have a 1978 gt50 (cafe project) which I'm trying to tune but keep reliable for road use any starting points?
Does anyone know the difference between the two, other than ones 5 speed and the others a 6 speed?
. ..
um, yeah, one is aircooled & the other watercooled, whilst the RG is kind of loosly based on the same architecture they are not the same engine by a shot. Also the running gear could not be more different.
http://www.suzukicycles.org/RG-series/RG50-Gamma_brochures.shtml
For a roadbike the safest route is a bigbore piston, should take you out to say 65cc, but you'd be lucky to find a listing, you'd have to adlib a bit but that means you'd need to take a punt & beware of different crown heights, pin positions & small end sizes (width compared to piston as well as dia) etc.
esp on a 5 speed you don't want to make it any more peaky.

[TZ350]

These crankshaft Balancing Posts started 17th June on Page 70.

(3) What the "Balance Factor" really is.

The "Balance Factor" 45%.....50%.......60%.........85% is the portion of the "Reciprocating Mass" that is balanced by the "Counter Balance", heavy side of the crankshaft.

(4) I will answer this question, Which is heavier, (A) the reciprocating weight of the rod piston assembly or (B) the counter weight of the crankshaft.


The counter weight only counters a % of the reciprocating weight and is always lighter than the reciprocating portion of the rod/piston assembly.

As an example, a balance factor of 65% means that the counter-weight portion of the crankshaft counter weighs only 65% of the reciprocating mass of the rod/piston assembly.

(5) Why there is a "Balance Factor" and what changing it does.

The Counter Balance reduces the up and down shake but increases the sideways shake. You have to make a compromise, a 100% up and down shake balanced out becomes a 100% sideways shake.

The compromise is the Balance Factor. The down side is that the Balance Factor is only good for a narrow rev range. The up side is that you can tweak the Balance Factor to aim the out of balance vibrations into the strong/heavy part of the frame. The Balance Factor can also be tweaked to move vibration to another part of the rev range that you don't use much.

Pic-1 on some cranks you can't see the counterbalance, you just have to imagine its there. On the cranks in Pic-1 the counterbalance (heavy side) is created by drilling holes near the crank pin.

Pic-2 you can see the cranks have different balance factors and the crank in Pic-1 has different size holes either side of the bigend this offsets the counterbalance as drawn in Pic-3.

Pic-3 shows that some cranks do not have the counter balance opposite the bigend. An example is the TF crank in Pic-1.

Pic-4 Thomas is holding a card showing how the angle of vibration changes with changes in balance factor. You can also tweak the balance factor to move a rough vibration patch away from a critical RPM.

.

[speedpro]

The percentages quoted are "mass".

The forces generated by the reciprocating mass increases linearly as a function of the rate of reciprocating.

The force generated by the rotating mass increases as a square of the rate of rotating.

Therefore, even though at standstill the rotating mass only exerts a force equal to say 60% of that exerted by the mass of the reciprocating parts, as the engine speed increases the forces generated by the rotating parts increases at a greater and greater rate and eventually equals the force being generated by the reciprocating parts. If engine speed continues to increase the forces generated by the rotating parts will exceed the forces generated by the reciprocating parts. The forces mathematically only equal each other at a single engine speed. We want that speed to be close to the operating speed.

On a single the forces at 90deg to the cylinder bore are unopposed regardless of the % used as there is no force generated by reciprocating parts to oppose them. 90deg V-twins are wonderful.

[TZ350]

.

Thanks Speedpro, that explains it very well, I was struggling to paint the picture.

.

[TZ350]

These crankshaft Balancing Posts started 17th June on Page 70.

(6) What to do with your "Balance Factor"

Pic-1 Find the weight of you're Reciprocating Mass.

Pic-2 For a Balance Factor of 55% say. Weigh out some washers untill you have a pile of them that weigh 55% or 0.55 X Reciprocating Mass.

Pic-3 Attach the washers to the end of the con-rod. Don't forget to include the weight of the cable tie.

You can reverse engineer this to find the balance factor of an existing crank.

.

[TZ350]

These crankshaft Balancing Posts started 17th June on Page 70.

(7) A simple but very effective jig for statically balancing a crank, that you can make yourself in 10min's. (Thanks Thomas)

Pic-1 Thomas showing of the balancing jig he lashed up in about 10mins.

Pic-2 The tubes act like a knife edges and are a very frictionless surface for the crank to roll on. The tubes are the key to the whole thing.

Pic-3 Nothing has to be flash. The only criteria is that its level and the tubes are parallel.

From Phill Irving. page 109 "the wheels will roll freely along the straight-edges and show no tendency to settle in any one position; if not, the pin will go to the top or bottom according to whether the Counter Balance is to heavy or to light. Correction is usually made by drilling the rims."

There you have it, the KISS method of re-balancing a single cylinder 2 or 4-stroke.

Very simple, very effective, a very accurate way to balance a single cylinder crankshaft staticaly. If anyone can come up with a better static balancing method, Thomas would like to hear about it.

.

[TZ350]

.

Re-Engineering to find the Balance Factor of a CrankShaft.


Pic-1 Hang things of the little end untill.............

Pic-2 ...........the crank no longer rolls and stays in whatever position it's placed.

Pic-3 Weigh the washers and the little end.

Pic-4 Weigh the Reciprocating Mass.

Divide the Weight of the Washers + weight of the Little End by the Weight of the Reciprocating Mass and there you have the Balance Factor.

Rearanging the formula I posted earlier.


Let:- "Washers"+"Little end" = A "Reciprocating Mass" = B and "Balance Factor" = C

Then Balance Factor C = A/B .............."Weight of the Washers"+"Weight of Little End"/"Weight of the Reciprocating Mass"




.

[Pumba]

:shit:For gods sake you need to get back to your day job. All this went well over my head along time ago and now with the amount of posts you are putting up there is bugger all chance of me ever catching up:shit:

[TZ350]

Yep I have got do something else, I know, I will take some more of those yummy meds. :eek:

[Pumba]

Pain killers, what a magical fruit:laugh:

[F5 Dave]

. . .

The forces generated by the reciprocating mass increases linearly as a function of the rate of reciprocating.

The force generated by the rotating mass increases as a square of the rate of rotating.
. . .

Fuck. Thanks Mike, now I have learnt something. That's all you needed to have said, something that I hadn't thought of but explains the change in amplitude with relation to the change of frequency. Makes sense but just hadn't bothered to think about it.

Then the frame acts as a damping cct as does the mass of the engine.

[TZ350]

.

F5 Dave, your comments and Speedpro's contribution add to this. Many thanks.

.

[Yow Ling]

OK all of this makes sense, however there is one bit I dont quite get. when weighing the reciprocating mass when it is still attached to the crank you will only weight a percentage of the rod. this is like weighing the back wheels of a truck and saying it weighs X tonne. shouldnt you have to weigh the rod and piston seperate from the crank. I think you will be out by more than half the weight of the rod

[TZ350]

when weighing the reciprocating mass when it is still attached to the crank you will only weight a percentage of the rod. this is like weighing the back wheels of a truck and saying it weighs X tonne. shouldnt you have to weigh the rod and piston seperate from the crank. I think you will be out by more than half the weight of the rod

Yes you'er more or less right, but this truck rotates at the front and reciprocates at the back.

Remember this is the KISS method and is a compromise. You could do a hell of a lot of math, and its still a compromise, just a smaller one.

The middle bit (Beam) of the rod poses a problem. It is neither totally rotating or reciprocating. It sort of wiggles. And the portion of reciprocating to rotating varies depending on the length of the rod.

Weighing the little end with the rod horizontal and free to rotate on the big end has been found, to be a good practical approximation of its reciprocating mass regardless of the rods length and works out to be about 1/3 of the rods total weight.

.

[TZ350]

Looking back I see I have left a photo out of one of the steps. it should look like this:-

Weighing the little end by its self.

When I get to work Monday I will get a good photo and quickly re-post them all in their proper order.

[sonic_v]

Force due to reciprocating mass given by following equation

Force = mass * r * w * w * (cos(angle) + cos(2 * angle) / n)


mass : reciprocating mass
r : crank throw, usually half of stroke
w : 2 * pi * revs/sec
angle : crank angle from tdc
n : rodlength / crank throw

The second term in brackets is the contribution of the secondary force. As not a lot can be done about it
poss best to ignore thus equation simplifies to

Force_primary = mass * r * w * w * cos(angle)


Hence force is directly proportional to the square of the engine speed.

All that this means is that the KISS method of balancing a crank is correct as all forces involved are proportional to square of engine speed.

[TZ350]

.

The KISS method of balancing a single cylinder 2 or 4-stroke.

Its all in the pictures:-

Pic-1 Find the total reciprocating Weight (Mass)
Pic-2 Find the Little Ends reciprocating Weight (Mass)
Pic-3 Find the Balance Facter (Ie. 65% is 0.65 X the ToTal Reciprocating Weight (Mass))
Pic-4 Leave the Little Ends reciprocating Weight (Mass) on the Scales
Pic-5 Attach the rest to the crank.
Pic-6 Balance the Crank.

From Phill Irving. page 109 "the wheels will roll freely along the straight-edges and show no tendency to settle in any one position; if not, the pin will go to the top or bottom according to whether the Counter Balance is to heavy or to light. Correction is usually made by drilling the rims."

Very simple, very effective, a very accurate way to balance a single cylinder crankshaft staticaly. If anyone can come up with a better static balancing method, Thomas and I would like to hear about it.

To find the existing balance factor of a crank shaft, you just more or less work through this process backwards.

.

[TZ350]

.


stuff the PM stuff... i think there are a couple of us that would like to know....:Punk:

Ok ajturbo, this is what I've done to fit TZR wheels to my RG50 Frame.

Pic-1 Bore the bearing housing right through and retain the bearing on the inside by a circlip or locktight.

Pic-2 Machine the sprocket carrior right back. Fit to the outside brg a small stepped sleeve with a 3mm sholder, Just like the original one on the inside of the back wheel. Trim the spacer part of off the inside sleeve. I used two of those spacer sleeves that are found between the sprocket carrior and back wheel brg, after trimming the spacer part of. File the swing arm slots for the TZR axle, Take care, must be accurate.

Pic-3 Mill both sides of the back wheel to the bearing including the disk mounts. I intend to weld the rear brake calaper mounting bracket to the 15mm long spacer. Planing on using a RG50 or Pit-Bike caliper.

Pic-4 Mill both sides of the front wheel back to the bearings, GP125 forks, RG50 Tripple clamps (RG50 legs will work too). TZR Front wheel mounts in backwards. Use RG50 or Pit-Bike caliper and need to make new calaper mounting bracket

Pic-5 Wheel brg sits flush against fork leg. The other side has a 15mm long spacer. Drill fork legs for TZR axil. Shorten and re-thread axil.

Pic-6 Made little mounting brackets to adapt RG250 footrest brackets to the RG50 frame.

Sorry, I have only got as far as having the wheels sitting properly in the frame. I have not done anything to the motor yet.

Hope this is a help to you.

.

[F5 Dave]

Good grief, that has 6 steps, AJ can't even make it around with a dozen fine quality beers to get a free disc. Expecting him to machine something to fit is quite optimistic.
Those a RG250 Mk2 or 3 brackets as I have found out today (I have some mk1s in the shed).

[bucketracer]

.

When I was around at the team ESE workshop yesterday I had the great fortune of meeting Thomas. We got talking about small 2-Strokes and drive-ability.

He showed me a RGV250 cylinder and pointed out the black oily gunk in the transfer ports. This gunk was high up in the port where the port exits into the cylinder. It was obvious that at some point in the rev-range there was blowback happening when the transfers opened.

Thomas pointed out that if this blowback could be stopped it would greatly widen the power band of the motor. He then drew some pictures of how it might be done using Fluid Diodes and told me that a Scroll Diode would probably be more effective in the transfers on a 2-Stroke than a Vortex Diode.

He said that in steady flow conditions the Vortex Diode looks like it would work better in the inlet but in a 2-Strokes unsteady flow the Scroll Diode has proven best. And that at high RPM the Scroll Diode is more effective than a reed valve. Looking at the pictures it all made sense.

The Team graciously gave me the OK to post these ideas and said they are looking into using it themselves and Fluid Diodes have been run experimentally in 2-Strokes. Where they showed no extra power but no loss of power either and a lot of real promise for widening the existing power band.

So here's a first for Buckets, to my knowledge anyway, the idea of using Fluid Diodes in the transfers and inlet to reduce blowback and thereby broaden the power band.

.

[ajturbo]

Good grief, that has 6 steps, AJ can't even make it around with a dozen fine quality beers to get a free disc. Expecting him to machine something to fit is quite optimistic.
Those a RG250 Mk2 or 3 brackets as I have found out today (I have some mk1s in the shed).


yeah sorry i was late... but i finally made it...



.



Ok ajturbo, this is what I've done to fit TZR wheels to my RG50 Frame.

Pic-1 Bore the bearing housing right through and retain the bearing on the inside by a circlip or locktight.

Pic-2 Machine the sprocket carrior right back. Fit to the outside brg a small stepped sleeve with a 3mm sholder, Just like the original one on the inside of the back wheel. Trim the spacer part of off the inside sleeve. I used two of those spacer sleeves that are found between the sprocket carrior and back wheel brg, after trimming the spacer part of. File the swing arm slots for the TZR axle, Take care, must be accurate.

Pic-3 Mill both sides of the back wheel to the bearing including the disk mounts. I intend to weld the rear brake calaper mounting bracket to the 15mm long spacer. Planing on using a RG50 or Pit-Bike caliper.

Pic-4 Mill both sides of the front wheel back to the bearings, GP125 forks, RG50 Tripple clamps (RG50 legs will work too). TZR Front wheel mounts in backwards. Use RG50 or Pit-Bike caliper and need to make new calaper mounting bracket

Pic-5 Wheel brg sits flush against fork leg. The other side has a 15mm long spacer. Drill fork legs for TZR axil. Shorten and re-thread axil.

Pic-6 Made little mounting brackets to adapt RG250 footrest brackets to the RG50 frame.

Sorry, I have only got as far as having the wheels sitting properly in the frame. I have not done anything to the motor yet.

Hope this is a help to you.

.

thanks heaps.. now to find a TZR wheel...:woohoo:

[Skunk]

thanks heaps.. now to find a TZR wheel...:woohoo:
I don't have any... Skunk Control does - try your luck if you're that stupid/brave. :laugh:

[ajturbo]

I don't have any... Skunk Control does - try your luck if you're that stupid/brave. :laugh:
one thing at a time...

first i need the fork seals replaced

then the front disc (thanks dave)
then the new front brakes... then to bed them in...

then a new front tire

THEN the new rear... but that will be after the GT gets going...

but it is good to know it can be done easily and i have a friend who wants to help with doing it... :woohoo:

[speedpro]

but it is good to know it can be done easily and i ... :woohoo:

Yeah that is real easy. :no: I was looking at a similar problem and decided on the whole chassis, suspension, and wheels. Much much easier.

[sonic_v]

.

When I was around at the team ESE workshop yesterday I had the great fortune of meeting Thomas. We got talking about small 2-Strokes and drive-ability.

He showed me a RGV250 cylinder and pointed out the black oily gunk in the transfer ports. This gunk was high up in the port where the port exits into the cylinder. It was obvious that at some point in the rev-range there was blowback happening when the transfers opened.

Thomas pointed out that if this blowback could be stopped it would greatly widen the power band of the motor. He then drew some pictures of how it might be done using Fluid Diodes and told me that a Scroll Diode would probably be more effective in the transfers on a 2-Stroke than a Vortex Diode.

He said that in steady flow conditions the Vortex Diode looks like it would work better in the inlet but in a 2-Strokes unsteady flow the Scroll Diode has proven best. And that at high RPM the Scroll Diode is more effective than a reed valve. Looking at the pictures it all made sense.

The Team graciously gave me the OK to post these ideas and said they are looking into using it themselves and Fluid Diodes have been run experimentally in 2-Strokes. Where they showed no extra power but no loss of power either and a lot of real promise for widening the existing power band.

So here's a first for Buckets, to my knowledge anyway, the idea of using Fluid Diodes in the transfers and inlet to reduce blowback and thereby broaden the power band.

.

some research carried out in Israel.

http://www.sae.org/technical/papers/830092

[Skunk]

1971 paper on Scroll diodes in two stroke engines...

[bucketracer]

Some Pic's of how scroll diodes work and how they could be used in a 2-stroke.

Pic-1 shows the key dimensions. The 30 inlet angle is important as is the r=2h.

Pic-2 shows how they work and where they could be fitted to a 2-stroke engine.

Abstract: from Sonic-v link

The typical convex torque of a simple two-stroke engine having a port-controlled piston is attributed to the backflow through the scavenge ports. It is proposed here to suppress the backflow by installing scroll diodes at the scavenge ports. Experimental observations on a fired engine demonstrate the remarkable improvement achieved with the diodes installed.

.

[F5 Dave]

That is interesting but anecdotaly that would have to have some effect on the flow in the same way that suzuki's old 1/2 case reed induction did on intake.

The difference between fluid & gas is that fluid is largely incompressible & gas is easily compressed. It would stand to reason that this would affect the std model as might the expected pressures designed for.

However an open mind, always experiment. know some crowd experimenting with rifled transfers. Didn't become the next big thing as far as I'm aware.

[TZ350]

Fluid Mechanics/Dynamics deals with the flow of liquids and gases.

The way a Fluidic Diode works is that in the forward direction the Fluid (gas) flows directly in a laminar manner from the inlet to the outlet but in the reverse direction Fluid enters the outlet and flows directly into a area of larger volume. A larger volume means reduced pressure and gas at a reduced pressure has more resistance to flowing back around the bend. Its no longer laminar and breaks up choking the entrance to the inlet. Like the sonic waves in the exhaust this can all happen at very high speed.

.

[Skunk]

The experiments with a two stroke are in the paper I put a link to. Page two has a graph of torque curves. I could get at the paper sonic_v linked to; got to pay a fee?

[Yow Ling]

I think you will find SS90 was going to mention the fluid diodes in post 820

[TZ350]

The experiments with a two stroke are in the paper I put a link to. Page two has a graph of torque curves. I could get at the paper sonic_v linked to; got to pay a fee?

Hi Skunk I could not open you're PDF document, something about Acrobat being unable to decript??

.

[Skunk]

Try this one.

[TZ350]

Try this one.

No... it dos'nt work for me either. Does it for you??? could my reader be the problem??

.

[Pumba]

Worked fine for me

[TZ350]

Worked fine for me

Ok.....problem my end then.:blink:...thats not unusual......just ask the missus..:laugh:

[craisin]

worrks fine on Ubuntu haaad tto click on view and then zoom in twice for my old eyes to reaad it

[craisin]

hey TZ my bought new from the warehouse 6years ago Dell cant open that file of skunks.
Ubuntu on the other hand is free and dual booting with XP is not a good ideA in the long run
Intels seem easier to manage with Ubuntu onboard sound is less problems.

I am different than a lot of linux freaks as its best to have a windows machine too

Trying to rux windows programs on ubuntu is a waste of time

:bye:

[TZ350]

ok here's one to send people down the garden path with a nice but difficult idea
http://www.muller.net/mullermachine/docs/slippy1.html
.


Slippy exhaust pipes

I was having a quick look at some old posts and re-discovered this from F5 Dave about adjustable length expansion chambers. It has to be a good idea, if it could be automated to work by itself even better. Now how to fit it onto my bike?????????????

From an Add for a RC Car exhaust:- The precisely engineered components of the Power Exhaust System use the unique exhaust pressure characteristics of 2-stroke motors to dynamically adjust the tuned length of the exhaust system. This is why Power Exhaust Systems can achieve maximum performance over a much wider RPM range than is possible with a fixed pipe. Changing of the tuned length is accomplished by the movement of the internal Tuned Assembly within the Power Exhaust Body.

While traditional tuned pipes focus on only one RPM range for maximum effect, the Power Exhaust System can boost performance throughout the entire RPM range. It’s (possibly) the world’s only tuned pipe that dynamically adjusts its tuned length during use.

"Tuned length" refers to the total combined length of the exhaust header and tuned pipe from the face of the piston to the end point of the convergent cone. This is the factor that is generally calculated first in pipe design. The tuned length is a function of certain fixed engine parameters and more significantly, a target RPM for maximum performance. Of course, a designer can only choose one target RPM. One RPM equals one best-tuned length. For a maximum benefit over a greater range of RPM you must change the tuned length.

F5 Daves might be better because only the rear cone moves but the RC Car pipe shows how it could be automated.

Pic-1 from F5 Daves post

Pics-2 to 4 is how RC Cars do it.

.

[TZ350]

.

"Tuned length" refers to the total combined length of the exhaust header and tuned pipe from the face of the piston to some point on the convergent cone. This is the factor that is generally calculated first in pipe design.

Danger Danger Danger There are two common ways that the term "Tuned Length" is used. Some people think tuned length is measured to the end of the convergent cone others measure tuned length to the mean reflective point half way along the cone. Thats half way along the complete cone with its pointy bit still on the end.

When talking about/compairing/calculating tuned lengths you need to know how the "Tuned Length" is being defined. Its an important difference, about 50-80mm or 1,000 to 1,500 RPM and can completly confuse your tuning efforts.

I am indebted to Thomas for pointing this out to me.

He also says that the sum of all the individual stages (cones) in Pic-1 should more correctly be called the overall length, and the overall length is most certinaly not the tuned length given by most/all formulas that you see for calculating the tuned length of an expansion chamber.

Most/all formulas for tuned length based on time and the speed of sound give a value for the length from the piston face to the mean reflective point of the convergent cone (Pic-2) and this is correctly called the "Tuned Length" because this is the mean distance/time the pressure wave travels out and back in the pipe.

Pic-1 Tuned Length. "tuned length measured to the end of the cone"

Pic-2 Tuned Length. "tuned length measured to the mean reflective point of the cone"

Pic-1 is wrong and Pic-2 is right as the "Tuned Length" is the mean distance/time the pressure wave travels out and back in the pipe.

.

[speedpro]

It's been done before in bucket racing, Peter Steadman. The end cone was slid back and forth by a servo, possibly a central locking solenoid. It had a cable pulling it in each direction. Remember Peter's bike has the stinger exiting from the centre section. I'm not sure why it wasn't persisted with. His bike was pretty quick without it so maybe it just wasn't worth the added complexity.

[FastFred]

Danger There are two common ways that the term "Tuned Length" is used.

When talking about/compairing/calculating tuned lengths you need to know how the "Tuned Length" is being defined.

.

TZ have I got this right??????

Formulas for tuned length based on "time and the speed of sound" give a tuned length measured to the mean reflective point of the cone"

Formulas for tuned length based on "time and the speed of sound plus a mystery bit” give a tuned length measured to the end of the convergent cone.

.

[TZ350]

TZ have I got this right??????

Formulas for tuned length based on "time and the speed of sound" give a tuned length measured to the mean reflective point of the cone"

Formulas for tuned length based on "time and the speed of sound plus a mystery bit” give a tuned length measured to the end of the convergent cone.

.

Yes you're onto it.

"Time" in the formula is worked out from the Rev's and Ex. Port Timing and the "Speed of Sound" is worked out from the Exhaust Gas Temperature.

Using these fundamental principals, Time X Speed = Length is the way Blair, Jennings Et. all, do it. This gives the "Tuned Length" measured to the mean point of the convergent cone.

Be suspicious of any other so called tuned length and ask how its calculated and where did the "extra bit" come from.

.

[pete376403]

Was cleaning out a pile of old magazines in the attics today, found a "Cycle" from January 1973. Has a very interesting article by Gordon Jennings titled "The aspirin-takers guide to port timing".
I could scan and post if anyone is interested

(for those who have never heard of him, Jennings was the guy who "Knew Stuff" before Kevin Cameron)

[bucketracer]

Was cleaning out a pile of old magazines in the attics today, found a "Cycle" from January 1973. Has a very interesting article by Gordon Jennings titled "The aspirin-takers guide to port timing".
I could scan and post if anyone is interested

(for those who have never heard of him, Jennings was the guy who "Knew Stuff" before Kevin Cameron)

Yes, please post it. It will be interesting to see if TZ knows his stuff.

.

[Fastborisracer]

Yes, please post it. It will be interesting to see if TZ knows his stuff.

.

It has already been posted many weeks back by TZ I think, re-posting is good but ya gotta wonder how well some people are paying attention.

[pete376403]

It has already been posted many weeks back by TZ I think, re-posting is good but ya gotta wonder how well some people are paying attention.

OK that will save me a bit of time. I couldn't get the PDFs under 1 meg anyway. What post (post number or date) I'll have look and see if its the same thing I've got. This one refers to an SAE paper from Yamaha engineers Naitoh and Nomura and the TD3 yamaha race engine. Same one?

[bucketracer]

Yes, Fast Boris, your right and in fact TZ seems to repost his ever increasing collection of interesting links every 10 pages or so, so they don't get to hard to find. I've just searched back and found them on page 70.

[pete376403]

Thanks, found it (post # 1040)
I'm not a bucket racer, just came across the mag article up in the attic and thought it could be useful. Oh well.

On another topic - crank balancing. Anyone suggested using mallory metal for crankshaft slugs? It is a bit heavier than the equivalent size piece of steel (for when you need to add weight)

[bucketracer]

On another topic - crank balancing. Anyone suggested using mallory metal for crankshaft slugs? It is a bit heavier than the equivalent size piece of steel (for when you need to add weight)

Yes, Speedpro has suggested mallory metal. Apparently MM is a bit heaver than lead.

[TZ350]

Thanks, found it (post # 1040)
I'm not a bucket racer, just came across the mag article up in the attic and thought it could be useful. Oh well.

On another topic - crank balancing. Anyone suggested using mallory metal for crankshaft slugs? It is a bit heavier than the equivalent size piece of steel (for when you need to add weight)

"I'm not a bucket racer, just came across the mag article up in the attic and thought it could be useful. Oh well."

Its all good, we need reminding, and often because people don't pay much attention to something untill they need it.

.

[pete376403]

Yes, Speedpro has suggested mallory metal. Apparently MM is a bit heaver than lead.

Depleted uranium is heavier again but there are problems getting it (altho there's a quite a bit laying around in Iraq);)

[TerraRoot]

what about water injection? the nsr500's used it to cool the pipe which changed the speed of the reflecting wave, think it worked too because they keep it right up until they the 2strokes got ruled out.

[koba]

what about water injection? the nsr500's used it to cool the pipe which changed the speed of the reflecting wave, think it worked too because they keep it right up until they the 2strokes got ruled out.

hmm, youve got me thinking!
Possibly an easier way to do it than slippy pipes, dialing it in would be hard tho.
Modern fuel injection systems give us lots of appropriate parts to work with.

[TerraRoot]

tbh, adjustable pipes or water injection are only gonna smooth the powerband not make more power, big strokers had em to tame there mighty horse's, are you lot scared with only 17 of em?

[F5 Dave]

That isn't 'smoothing the power'. That is extending the torque curve, boosting the midrange, increasing the over-rev. All things small capacity bikes could use. Whether the complexity & weight is worth it is dubious.

Any manual system is just going to take your eye off the ball when trying to ride & do something else, which is why I posted the idea originally presented as I did. But go crazy.

[speedpro]

Never EVER letting the clutch right out can help as well by giving an apparently very wide peak power, from a road-speed perspective anyway, eh Dave.

[F5 Dave]

Yeah not so much a riding style as sloppy maintenance, I adjusted it like that & well,. . . ;)

[bucketracer]

Old (1975?) DKW 125 MotoX engine, check the size of the finning and the fins on the bottom end. Note the gap around the crankcase, I guess this is to reduce heating of the incoming air/fuel mixture. Didn't TZ say somewhere that a large part of an engines waste heat is dissipated from the bottom end.

[TerraRoot]

how about this for fixing your powerband hi-tech style. e-tec 600 ski-doo.

First a video
http://www.youtube.com/watch?v=N_DexODwAb0

Ignore the environmental stuff, note how smooth it is? and all the oil is not ending up in the combustion chamber, upping the octane value to boot.

what can us guys in our sheds do? A company called envirofit is making a retrofit kit for small old aircooled two-strokes.

http://envirofit.org/?q=our-products/2-stroke-retrofit

Basically, doing this conversion to DI, you ought to be able to control every aspect of the engine, advanceing/retarding the fuel injection, smoothing out the powerband should be no problem.

God i just hope it's not vapourware.

[bucketracer]

First a video
http://www.youtube.com/watch?v=N_DexODwAb0

Is it just me, or has anyone else noticed that there was much less snow on the Ski-Doo's seat and runners, suggesting it had already been run up/or was covered before the test?????

Direct injection into the cylinder, interesting idea though.

.

[TZ350]

Direct Injection is a serious idea that seems to be getting some traction, could be the revival of small 2-Strokes.

.

[Chambers]

Optimization of a Direct-Injected 2-Stroke Cycle Snowmobile
Document Number: 2003-32-0074

Date Published: September 2003

Author(s):
Walter Hull - Colorado State Univ.

Abstract:
A student design team at Colorado State University (CSU) has developed an innovative snowmobile to compete in the Clean Snowmobile Challenge 2003 competition. This engine concept was originally developed for the CSC 2002 competition and demonstrated the lowest emissions of any engine that competed that year. The team utilized a 3-cylinder, 594cc, loop-scavenged, two-stroke cycle engine (Arctic Cat ZRT600) and then modified the engine to operate with direct in-cylinder fuel injection using the Orbital OCP air-assisted fuel injection system. This conversion required that the team design and cast new heads for the engine. The direct-injection approach reduced carbon monoxide (CO) emissions by 70% and total hydrocarbon (THC) emissions by 90% from a representative stock snowmobile. An oxidation catalyst was then used to oxidize the remaining CO and THC. This combination of direct fuel injection and oxidation catalysts reduced CO by over 97% and THC by over 99% when compared to the 2002 SAE CSC control sled. The design discussed in this paper builds on the core technology developed in 2002 to improve performance and reduce noise.

The direct-injected engine and supporting hardware were transferred to a lightweight 2002 Arctic Cat ZL600 chassis. The modern suspension and the reduced weight of the chassis resulted in improved handling, increased acceleration and improved fuel economy.

The 2002 entry exceeded the competition noise limit by one dBA. A comprehensive effort was undertaken to redesign the exhaust system to reduce noise, improve power, and to more effectively accommodate the oxidation catalyst. Analytical and experimental techniques were used to redesign the exhaust system which demonstrated a 20% improvement in peak power and mid-range torque over the 2002 entry. Improved materials are utilized to withstand the high temperatures produced by the oxidation catalyst. The new exhaust silencer design combines a diffusive silencer, a side resonator, and an absorptive silencer. Intake noise is attenuated with a combined diffusive silencer and side resonator silencer. The exhaust and intake silencers were effective in reducing the engine?s firing frequency and the first four harmonics.

A cost analysis has shown that this complete design approach would add $473 to the production cost of manufacturing the snowmobile. The majority of this cost is incurred by the direct fuel injection system and the modifications to the exhaust system.

.

[Chambers]

Wait and there is more:-


High Specific Power Output Direct Injection 2-Stroke Engine Applications
Document Number: 2005-32-0066

Date Published: October 2005

Author(s):
Rodney Houston - Orbital Australia Pty. Ltd.
Greg Bell - Orbital Australia Pty. Ltd.
Steven Ahern - Orbital Australia Pty. Ltd.

Abstract:
Whilst direct in-cylinder injection is now common in both the automotive and non-automotive markets, the very high-performance, 2-stroke engines pose specific challenges to the application of direct injection due to the increased fueling levels, the high fuel turn down ratio requirements and the reduced fuel preparation times at high engine operating speeds.

In addition, a high-performance, 2-stroke engine will usually have a highly tuned scavenging system, which puts further demands on the fuel and combustion systems to achieve the desired performance. The fuel and combustion systems must also retain the low emissions to meet the relevant emissions legislation with a minimum level of aftertreatment. This paper briefly discusses the requirements for emissions reduction in high-specific-output, 2-stroke engines, whether it is for a high-performance motorcycle application that only uses relatively low loads across the emissions testing cycle or for a highly loaded and high speed snowmobile application.

This paper then reviews some of the specific challenges and latest developments for an Air-Assisted Direct Injection (ADI) system and the accompany combustion system to address the operating requirements of high-performance and high-speed, 2-stroke engines.


So Yes it looks like DI is being taken seriously and could be made to work with race 2-stroke engines.

.

[TZ350]

.

In moments of desperation or bad judgement racing someone for the next corner I have often slowed myself down by holding a gear to long, and making the motor rev way past its power peak.

And later thought, if there was an automatic way to change gears when the motor touched peak rpm the bike could accelerate much more smoothly and quickly.

When I was in JayCar’s yesterday I spotted this kit KC5378. It’s a frequency switch that will switch devices on or off according to engine rev’s. This could trigger an electric door lock attached to the gear lever when the motor hits peak rpm.

I could control it by setting it up so that it only works when I have my thumb on the horn button. Then at the right times All I would need to do is have my thumb on the button and keep the throttle nailed for fast seamless acceleration.

.

[Skunk]

Or do it Sketchy's way... hold your foot on the gear lever (race pattern) and push the kill button to cut the ignition for a moment and the gear changes as the motor drops it's loading. Done.

I would, however, be interested in that kit to limit the revs.

[TZ350]

Or do it Sketchy's way... hold your foot on the gear lever (race pattern) and push the kill button to cut the ignition for a moment and the gear changes as the motor drops it's loading. Done.


Next time out I will try that.

.

[Pumba]

Home made quick shifters in buckets, dont know why, but I have a funny felling this may not end well:blink:

[F5 Dave]

Yeah I've had my project one on breadboard for 14 years. Even made the gear linkage switch & a charge pump so no battery reqd. Filed under 'one day when there is less important things to do'.

[Skunk]

Too many project huh Dave? :whistle:

[F5 Dave]

Too many projects & not enough arms that work atm.

[TerraRoot]

More info on DI.

Since the most popular DI bike i can get my hands on is a aprilia sr50, i went a searching there. and found a whole sub forum doing the megasquirt thing
http://www.scooter-freaks.nl/forum/showthread.php?t=274376

okay it's only a 50, but i can't find any bigger ADI injectors anywhere, so maybe just double or triple up on 50cc injectors? arrange them around the standard spark plug and use one big air pump and fuel pump.

All the technology is out there and tested except for the ADI injector and the need to make a need head to house the spark plug and injector. easy eh?

[TZ350]

All the technology is out there and tested except for the ADI injector and the need to make a need head to house the spark plug and injector. easy eh?

Please keep us posted as your project with the DI progresses.

.

[TerraRoot]

sorry if im sounding like an arm chair engineer.
just want to pick other peoples brains on how they would do it

[TZ350]

sorry if im sounding like an arm chair engineer.


New ideas and arm chair engineering its all good, all interesting and DI and the engine management that goes with it, I think is an interesting idea with potential.

Sorry if I mis-read you, I was becoming concerned, that DI was about to be promoted (pushed) as an idea that Team ESE should pickup.

From experiance I know the time and effort it takes to make even the easiest idea work.

And even with DI you still have to get the air into the cylinder using all the familiar 2-stroke tuning techniques. From what I can see, the DI bit just cuts down on wasted fuel but has some potential for cooling the piston crown.

For performance, cooling the piston crown is a good idea, and worth looking into, I will certainly look into it some more myself.

Its all good, many thanks TerraRoot for your input. Team ESE.

.

[TZ350]

.

More on cooling the piston crown and a little off topic.

Water is too brutal to squirt onto a hot piston crown, it causes the alloy to fracture. But in the past I have toyed with the idea of injecting nitromethane to cool the piston crown. I was going to squirt it up into the underside of the piston from below.

I figured the liquid nitro would hit the hot underside of the piston as it descended and opened the transfer ports. As the liquid nitro burst into vapor it would cool the underside of the piston crown and the vapor pressure would help eject the airfuel mixture out of the crankcase and up into the cylinder.

I reasioned, that with the motor tuned to run correctly on petrol in the ordinary way, adding nitro, as nitro is 48% oxygen 52% fuel there would be no problem as it would make the motor run slightly richer and hopefully stronger.

I did try this out once, it made the motor run hotter suggesting more power but strangly it wen't no faster. The good thing was it did not blow up so I was right about the mixture. I am not sure why it did not run stronger, maybe an ignition timing thing or compression issue. Just out of curiosity I would like to get back to it one day and get it right as I have always wanted to run a Bucket at speed around a long track like Pukekohe.

If anyone else has experimented with using nitro as a chemical supercharger in a 2-stroke I would be interested to know how it worked out.

DI and nitro could have real performance possibilities.

.

[TZ350]

.

A link to the Mega Squirt manual that TerraRoot is talking about. http://www.megamanual.com/index.html

Looks interesting, could have possibilities.

.

[speedpro]

Nitro is lovely but stuff does go bang. Actually it goes BANG. I remember yakking to John Boyle about it years ago and he reckoned 10% in alcohol smoothed the idle and generally made all sorts of improvements. Nitro doesn't mix with petrol I think. There was a small rail years ago at Thunderpark that used to start on alcohol and switch to nitro. You could hear the change in the exhaust note. Robert Holden rode Bob Brown's(I think) Ducati on a Methanol/Nitro mix. Made your eyes water and your nose sting.

[TZ350]

Nitro will mix with petrol but the problem is nitro does not like a lean situation at all and will detonate at the slightest hint of leanness and petrol does not like to be run too rich so its a difficult balancing act running a nitro/petrol mix. But methanol/nitro is much easier to use as methanol loves to be run rich.

My method was to not mix the nitro and petrol directly but to set the bikes carb up on a generous petrol setting by itself so the motor was running on the slightly rich side of the correct air/fuel ratio for petrol. Then to squirt nitro in as an extra. Nitro carries slightly more fuel than oxygen so when it is injected the motor richens up even more. Being richer than it really needs keeps things safe.

.

[TZ350]

.

Nitro is a slow burner so you need extra advance. This slow burn is why you see the top fuel dragesters flaming out the exhausts.

To speed the burn rate up you can add hydrazine (Now Banned). The correct amount is 1/4 of 1% add 2-3% hydrazine to nitro and you have a very explosive mix.


Pic-1 a 60's rail dragster.

Pic-2 is what happens when you add to much H. Hydrazine The Doomsday weapon of the sixties.

The attached image is a Top Nitro Fueler staging. Thats big time Nitro, don't you just love it.

Yes, one day I will get back to trying nitro in my Bike again, just for giggles mind. :msn-wink:
.

[F5 Dave]

Just for giggle ok, but people reading the thread shouldn't get the idea that it is legal for racing to add any fuel other than petrol to a bucket.

[Skunk]

Just for giggle ok, but people reading the thread shouldn't get the idea that it is legal for racing to add any fuel other than petrol to a bucket.
Damn! Anyone want to buy 100 litres of liquid nitro?

[TZ350]

Just for giggle ok, but people reading the thread shouldn't get the idea that it is legal for racing to add any fuel other than petrol to a bucket.

Nitro is strictly for giggles, a bit of track day fun.

.

[TZ350]

.

Another usefull kit from JayCar. Kit number KC5466 $29 aprox. Its a CDI kit to replace a bikes blown CDI. This could be adapted in all sorts of ways.

It uses the bikes own high voltage stator coil to charge it and the trigger coil to fire it.

I am going to see if I can use it with the programmable ignition kit I started playing with before.

Also if anyone knows how the retard part of a CDI circuit is arranged I would love to know.

.

[pete376403]

.
Nitro is a slow burner so you need extra advance. This slow burn is why you see the top fuel dragesters flaming out the exhausts..

Maybe not - "Nitromethane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases."

http://www.ultimatecarpage.com/forum/miscellaneous/20271-top-fuel-dragster-facts.html

Ronnie Moore used Nitro fuel in his speedway bike for the World Champs back in the '60s. Nitro was very hard to get in England at that time - he visited every model shop in London to purchase bottles of model plane fuel. Seemed to work - he won the world title

[koba]

Nitro is strictly for giggles, a bit of track day fun.

.

I thought you were talking about NITROmethane and not NITROus oxide, now I'm all confused :confused:

[TZ350]

.

Hmmmm Blue Bottle, Puff Puff

Deep Breath Now......... Gigggle........gigggggle ...What!.....Nitromethane.....Nooooo...he..he....h e..he.........

.

[bucketracer]

.

More of the 1975 DKW Mx Engine, 54 Bore 54 Stroke 21Hp Six Speed.

Pic-1 Crank Shaft

Pic-2 Squish Head (with incorrect plug fitted)

Pic-3 Massive Cylinder Finning, Short Exhaust Tract

Pic-4 Cylinder Ports

Pic-5 Crank Case and Head Finning

Pic-6 Angle and Shape of Transfer Ports.

Notice the gap around the carnkcase and the shape of the transfer and how the case at the top of the flywheel blends into the transfer. Sorry I did not think to make a portmap or measure the port timing.

.

[ajturbo]

how the fuck is this going to make my RG go faster????

[bucketracer]

.


how the fuck is this going to make my RG go faster????

I refuse to answer that question on the grounds that I don’t know the answer.

.

[diesel pig]

.



I refuse to answer that question on the grounds that I don’t know the answer.

.

DAM you and your honesty:innocent:

[Buckets4Me]

DAM you and your honesty:innocent:

If you polish the head and lap the valves you will get an extra 13.5 hp out of that old RG :woohoo::scooter:

[ajturbo]

trouble is that the last time i "lapped the valves" on the RG50... i found i did too good a job and now i cannot find them....:bash:

[F5 Dave]

The valves are on the underneath of the barrel, 1/2 case reed induction.
2 more are in the tyres. You may also wish to consider the fuel tap a 'valve'.

[ajturbo]

you really think i need the valves in the tires?.. saves weight if not...

[F5 Dave]

No that is a common miss-perception. As air in the tyres is a positive pressure; every pound added, is a pound off the total curb weight.

There is of course a trade off in grip if you apply too much pressure, but if you keep it below 45psi I think you will make up for your extra girth compared to the jockeys out there.

[ajturbo]

thanks for the heads up dave....

hope it rains on sunday... i have wets front and rear!!! wooo hooo

[Buckets4Me]

you need to put a bigger fuel tap in as well
and raise the tank up (as this gives it more presure)
so now you will have more fuel flow and more presure behind it you now need bigger carbs and a wilder cam :crazy: :scooter: :wari:

go the mighty RG :wari:

[ajturbo]

you need to put a bigger fuel tap in as well
and raise the tank up (as this gives it more presure)
so now you will have more fuel flow and more presure behind it you now need bigger carbs and a wilder cam :crazy: :scooter: :wari:

go the mighty RG :wari:
wilder cam?????

i could weld that to the radiator.... think that would help?

[TZ350]

Some of the better Links. Posted here together on page 80 so they can be easily found. :blink:

Came across this on ignitions. yes its cars and 4-stroke but informative nevertheless.
http://www.max-boost.co.uk/max-boost/ignition_deeper.htm

Gordon Jennings:- http://www.vintagesleds.com/library/manuals/misc/Two-stroke%20Tuner%27s%20Handbook.pdf

An assortment of Gennings Articles:- http://www.edj.net/2stroke/jennings

Graham Bell:- http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving. http://www.scribd.com/doc/15392252/Tuning-for-Speed-P-E-Irving-1965-Tuning-Racing-Motorcycle-Engines

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

Yamaha SAE Paper on Porting:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

Ignitech ignitions:- http://www.ignitech.cz/english/aindex.htm

This http://www.geocities.com/a57ngel/moto/CDI.html talks about repairing/modifying a KDX CDI's retard curve, there is also a schematic.

Gold Mine 1:- http://www.2stroke-tuning.nl/media/

If there is any rule for the inexperienced to keep in mind. it is that everything a reasonable intelligent person should intuitively believe to be right will probably be totally wrong. http://www.bmw-m.net/techdata/cylinder.htm The inlet port needs only a slight convergence of 1.5 degrees included angle, which doesn't sound like much. But a 12 inch section of aluminum pipe taper-bored for a 1.5 inch inlet and a 1.498 inch outlet flows better than a parallel-wall pipe, and a lot better than air going from the cones' small end to it's beg end. Sound waves love a divergent duct, air flow does not.

How a 2-Stroke realy works.
http://www.southernskies.net/page_info/runningtwostrokeengine.html

ok here's one to send people down the garden path with a nice but difficult idea
http://www.muller.net/mullermachine/docs/slippy1.html

Here is an online Squish Velocity Program. There is also a few other useful programs.
http://www.torqsoft.net/squish-velocity.html

http://www.torqsoft.net/piston-position.html

Terminolagy:- http://www.2-stroke-porting.com/terminology.htm

MSV Mean Squish Velocity Calculator:- http://myweb.tiscali.co.uk/teamsparrow/cylinderheadsv2_3.xls

Simulation video clips of 2-stroke scavenging:-
http://video.google.com/videosearch?client=firefox-a&rls=org.mozilla:en-GB:official&channel=s&hl=en&q=two+stroke+scavenging&um=1&ie=UTF-8&ei=-EUFSunlCcjJtgeG2K2XBw&sa=X&oi=video_result_group&resnum=4&ct=title#

A catalog search engine, pistons, rod kits etc.
http://www.who-sells-it.com/r/mahle-pistons-2-stroke.html

Using only one ring:- http://www.vintagesleds.com/library/manuals/misc/jennings/l-ring_effect.pdf

The effects of higher compression ratios in a 2-stroke:-
http://www.vintagesleds.com/library/manuals/misc/jennings/higher_compression.pdf

From, Yow Ling. www.zeeltronic.com has fully programmable cdi's about 100 euros.

Stan Stevens RGV Tuning:- http://www.stanstephens.com/rgv.htm.

It might be Karts, but there is a bit of interesting reading here.
www.kartweb.com/TechArt/2Stroke/chapter1.doc
www.kartweb.com/TechArt/2Stroke/chapter2.doc
www.kartweb.com/TechArt/2Stroke/chapter3.doc
chapter 3 is on chambers.

A MacDizzy Blaster Engine Rebuild with Photos:- http://www.macdizzy.com/1989hhopup.htm

MacDizzy's:- http://www.macdizzy.com/

Modifying a Suzuki open chamber to a squish head:- http://www.ozebook.com/compendium/t500_files/morgan/head.htm

Dispelling 2-stroke tuning myths:- www.fatbaq.com/RS125_dispellingmyths.doc

Rate of Fuel Burn:- http://www.factorypro.com/tech_tuning_procedures/tuning_fuel_octane_vs_power.html

Reading Plugs:- http://www.dragstuff.com/techarticles/reading-spark-plugs.html

Engine formulas:- http://members.bellatlantic.net/~vze2p5sj/modelengines/engine1.htm

A Handy Coverter:- http://www.mr2ownersclub.com/converter.htm

Detonation:- http://www.factorypipe.com/t_deto.php

Dale Alexander. The Art Of Squishing Things Until They Make Power:-
http://www.aircooled-rd.com/default.asp?txtPage=squish1.htm
http://www.aircooled-rd.com/default.asp?txtPage=squish2.htm
http://www.aircooled-rd.com/default.asp?txtPage=squish3.htm

A preview of Kevin Camerons book “Sportbike Performance Handbook”:-
http://books.google.co.nz/books?id=LswdRd2Zm8YC&pg=PA85&lpg=PA85&dq=tz250+detonation+repair&source=bl&ots=zYYDz0MEyv&sig=pRPBbN00SOAg-wfME3O1YZCk9KU&hl=en&ei=Ve2tSb6iBYT06QO585zgBQ&sa=X&oi=book_result&resnum=1&ct=result#PPA81,M1

TUNING VESPA'S THE NORRIE KERR WAY.....
http://www.scooterhelp.com/serial/tuning.books.html

Crankcase delivery ratios and inlet timing for rotary disk motors:-
http://www.edj.net/2stroke/jennings/delivery_ratio.pdf

The effects of crankcase volume on the delivery ratio:-
http://www.edj.net/2stroke/jennings/crankcase_volume.pdf

Piston pin offset and what it means for extra power:-
http://www.motorcycleproject.com/motorcycle/text/cows-offset.html

4-Stroke stuff but very interesting about porting and combustion.
http://www.gofastnews.com/board/technical-articles/

Supercharged Honda 50 http://www.elsberg-tuning.dk/the%20bikes.html

Drop your engine in liquid nitrogen:- http://www.iwt.com.au/cryogenics.htm includes dyno charts to prove the theory. Thanks Yow Ling.

The Big Tuning Manual from Piper Cams:- http://www.bgideas.demon.co.uk/tmanual/ it talks about combustion chamber shape and swirl patterns, and are PDF's that can be down loaded.

A jpg file of a degree wheel that you can download and print out.
http://www.eurospares.com/graphics/degreew.jpg

And also from Euro Spares a "Bibliography of Technical Books."
http://www.eurospares.com/techbook.htm

Someone else's efforts at porting:- http://www.teamsmoke.com/photo4.html

In many cases a non-squish combustion chamber, with its complete utilisation of the mixture to offset the power-limiting effects of a necessarily-lower compression ratio, has proven to be best in absolute terms of power and economy. http://toostroke.blogspot.com/2007/12/squish-bands.html

A cataloge search engine of all things!!!!!! Lots of 2-stroke piston stuff. Probably can find rod-kits and other bucket stuff if you look. http://www.who-sells-it.com/r/mahle-...-2-stroke.html

.

[bucketracer]

http://homepage.mac.com/rg500delta/deltaphasetwo/Frames/pipe_design.html

for Rg500 but its alot about pipes :first:

Originaly posted on the 2-Stroke Tuning Thread.

A very interesting read.

.

[TZ350]

I had been accumulating bits and pieces to make a flow bench test rig for testing the transfer ports. It was going to be a variable speed blow through system with smoke.

Then on the two-stroke tuning thread SS90 reminded us about Gordon Jennings description of a test rig, ( http://www.vintagesleds.com/library/manuals/misc/Two-stroke%20Tuner%27s%20Handbook.pdf page 122). It is fairly simple and easy to make. Thomas and I knocked one up in a couple of hours.

For a smoke trace we researched how smoke machines work and found that car anti- freeze dripped onto a soldering iron made smoke. Read more here:- http://www.electricstuff.co.uk/smokegun.html

Unfortunately this is wet smoke and condenses on the underside of the flow rigs window. Read more about making your own smoke fluid:- http://www.bigclive.com/smoke.htm

The condensing water vapor obscures the view of the scavenge patterns but you can see the droplets being driven across the window and get some idea of what is going on inside. Dry smoke would be better.

Pic-1 The basic rig.

Pic-2 The piston plug (height adjustable)

Pic-3 Smoke from the soldering iron being sucked up the transfer port

Pic-4 Short-circuiting from the main transfer to the exhaust port

Pic-5 Water droplets being driven across the window

.

[ajturbo]

OOOOOOOOOOooo

AHHHHHHHHHhhhhhhhhhhhh... that is so cool!!!

[F5 Dave]

um yeah all very interesting, but I wonder what sort of conclusions you are going to draw from all that? Perhaps a big deflector piston?

There is of course pump action & suction occurring & they happen at differing times & none are constant.

Obviously there is no measuring occurring (most modern tuners spurned those types of flow benches in the 80s anyway), so you are only looking at patterns.

Mk2 should blow considerable amounts of smoke rather than suck small amounts. As I've said before, my pattern flow bench is the tap aimed at the transfers bottoms. It is fully adjustable & you only need the washroom sink, but you have a good idea where the transfers are aimed at, at least in favorable conditions.

[TZ350]

um yeah all very interesting, but I wonder what sort of conclusions you are going to draw from all that? Perhaps a big deflector piston?

Mk2 should blow considerable amounts of smoke rather than suck small amounts.

As I've said before, my pattern flow bench is the tap aimed at the transfers bottoms. It is fully adjustable & you only need the washroom sink, but you have a good idea where the transfers are aimed at, at least in favorable conditions.

Deflector Top Piston, of course that’s what we are going to do, welding up one of my best pistons now. Cutting the head back with an angle grinder and chiselling the swirl pattern grooving into the cylinder wall.

We have tried water and you can definatly see where the transfers are aimed but I wanted to see the looping of the transfer streams. I particularly wanted to see how symmetrical they are and how they scaveng the combustion chamber, if at all.

As crude as it was I could still see the transfer streams swirling around in a circle above the exhaust port. Small shifts in the shallow convex window changed the swirling pattern. I don't know what any of this means yet, but its early days.

When we tried water we could only squirt it down one transfer at a time, and even then could not completely fill the transfer duct so we only got a partial look at how the streams behaved.

We plan to try it again, with a better system to squirt the water through both opposing transfers at the same time. I think water could be a good way to check the symmetry of the ports and the hight and angle they meet at.

I am not sure what we will learn but it must be worth a look. Any one could do this, its real fun backyard stuff.

.

[SS90]

Deflector Top Piston, of course that’s what we are going to do, welding up one of my best pistons now. Cutting the head back with an angle grinder and chiselling the swirl pattern grooving into the cylinder wall.

.


F5dave brings up a point.

But I will go a little further based on my experience.

Flowing water from a tap through each port is a quick way to check if you have each side EVEN (critical) but doesn't really show you what each pattern achieves when it comes to "looping", but it is good to build a "data" base from for each different pattern you try.

Also, F5dave points that you cant take into account the effect of the expansion chamber, which again is quite right. However, that is why you have to build up a small" data base" of what you perceive to be the best pattern, compared to the results you get on the dyno.

Personally, I find the somewhat messier (but easier to read) method of starting with an old set of cases (crank as well) and adapting a inlet from a garden hose along with compressed air (via a sensitive pressure regulator).

The exhaust port connects to a 44 gallon drum (or maybe just out the window as I do).

Control the air pressure (only a small amount is needed).

The air bubbles then represent the "Shnürle loop"

Again, it doesn't take into account the expansion chamber, but it is "controllable" in so far as the "identifying medium" is concerned (air bubbles)

It may take a few nights concentrated work.

Also, my personal suggestion would NOT be to use a "deflector" type piston (that is of course returning to a "cross flow" engine)

They do have distinct advantages, but you will find (as others have) the uneven piston crown thickness will cause heat dissipation problems for you.

I am also fairly certain (almost 100%) that with such a piston (defletor/cross flow) there is no way in hell you could run the compression ratios you are, and certainly not use a "squish band head".

Such designs are suitable (in my experience) only for low spec,slow running designs. (Scooters from the 30's is an example), but I know that some outboard motors (not high spec ones) still use it, but they are fuel injected, and designed to run at mid throttle for long periods), which cross flow engines are very good at, due to their superior scavenge flow.

But try to subject them to prolonged "full throttle (high load) use, and the combustion temperature goes through the roof.

I rode a friend's 1951 "cross flow" engined scooter from here to Austria 2 months ago (200 KM) and, at what I would guess to be 55 KMH (no speedo's in those days) and maybe 3,000 RPM (again guessing) the engine was very interesting to ride...no "power" to speak of (125cc) but the "power delivery" was quite like anything else I have ridden, smooth, linear and used almost no petrol at all.

It seemed to have power from as little as 600 RPM, but only revved to (max I would say 3000 RPM)

Ironically, at those speeds I had plenty of time to think about scavenge patterns!

I suspect that adding an expansion chamber into the equation would complicate matters more, though I have never tried that one.

I am of the opinion that since you have the dish in your piston, you should create a pattern that utilises that to your advantage (as far as the rear boost port is concerned)

BUT, you must make a clear cylinder head to the same specs as your alumnium one,(then spend the afternoon polishing it so you can see through it, because don't forget, your cylinder head is part of the system.....you can't get a good idea of your scavenge pattern with a flat dish!:no:

[TZ350]

Flowing water from a tap through each port is a quick way to check if you have each side EVEN (critical) but doesn't really show you what each pattern achieves when it comes to "looping", but it is good to build a "data" base from for each different pattern you try.

I am of the opinion that since you have the dish in your piston, you should create a pattern that utilises that to your advantage (as far as the rear boost port is concerned)

BUT, you must make a clear cylinder head to the same specs as your alumnium one,(then spend the afternoon polishing it so you can see through it, because don't forget, your cylinder head is part of the system.....you can't get a good idea of your scavenge pattern with a flat dish!:no:

Thanks SS90 for your reply.

I was just giving (or trying to) give F5 a laugh with the deflector piston.

I have come to like my dished piston and the small compact combustion chamber that it gives me. I run a spark advance of about 16 degrees compared to about 26 (std is 20) for the other open chamber ESE engines which are similar in all other ways, that must mean something.

From my brief experimenting I can see your right about having to have a faithful replica of the actual cylinder head, I always expected I would have to make one.

I set my piston plug up so it was adjustable, now I can look at the flow pattern and how it changes as the port opens.

The water and air rig you describe sounds good, I have a spare complete bottom end. It might just become a flow rig now.

In fact I think that’s the direction we will go in next. We could blow smoke through it and/or air/water like you describe.

I can see myself getting very wet playing with it, so lots of fun.

.

[SS90]

Interesting that you find 16 deg to be suitable.

In this scene, (if you have a static ignition set up) it is considered "finite" to set it at 17 Deg, which not surprisingly is where Vespa set their small frame engines to factory.

I have found (with a static system) that much over 20 deg and you increase the chances of holing a piston dramatically.

Of course this is only in relation to cast iron high tuned stuff with high cylinder compression, the aluminium gear is less likely to have a problem, but, still its considered "S.O.P" to set any tuned (non retarding) ignition to 17 Deg, and all unmodified stuff will run up to 25 deg with out problem (Albeit a little hotter than normal)

I am personally interested in seeing your results as to what sort of pattern you get originally, then compared to when you crank up the water pressure (which has a similar effect to having higher primary compression)

One word of advise, to save time, when you change angles (particularly on the boost port/secondary transfer area), use a "hot melt glue gun" as a filler material, just before it cools, using a surgeons rubber glove, with you finger dipped in water/dishwashing liquid smooth it out to somewhere near the angle you want. You can change the angle to where you need by using a flat skinny blade slightly heated.

It really quick, cheap, and no problem if you stuff it up.

When you get what you want, you can later replicate it with a good quality devcon filler.

2 weeks ago, I had some Devcon fall out (been in there 1 year), Amazingly no damage, but a cautionary tale for sure!

This particular engine had been DRAMATICALLY over heated 3 race meetings before (he hadn't checked the squish with a new piston) and I suspect that the overheating caused the Devcon to shrink when it cooled down, as I have never had that happen before.

While I admit my first scavenge patterns where complete SHIT, by the time I had finished I went from 15NM and 21.7PS to 19NM and 20PS, a new expansion chamber, and a suitable primary compression ratio to match and 20NM and 24PS, all with no squish band head.

I don't expect that Suzuki with the GP125 where as bad as my first attempts, but it indicates to me that there is substantual gains in Torque, particularly at lower RPM. And we always forget that a Two stroke is so damned good at producing torque!

[F5 Dave]

Hard to compare static ignition points unless running ignitions with nill retard, the other ESE ignitions may have a different year ign (if all using KX) which have mondo retard. 26 deg will make for good idle & off idle performance & then back off as revs rise.

I try to rough grind & centre-punch some divets (if room) to get Devcon to adhere. Then metal cleaner. Brilliant stuff. Pity it doesn't last in exhausts.

[TZ350]

No retard, the 16 and 26 were set using a dyno and have run reliably in the field. The particular KX ignitions used have no retard at all, just a static fixed point.

So 16 and 26 is interesting as the only real difference between the motors is the combustion chamber shape.

We are going to trial a RM ignition that has retard (not sure how much) on the 26 open chamber motor soon, hopefully next week we will be able to get to the dyno at Henderson Yamaha.

.

[F5 Dave]

Yes I've had different settings with different heads when trying out things (often with no appreciable change in performance, sometimes with).

[k14]

Rather than stuff around with other ignitions, just buy an ignitech. I bought one for my CB a month ago and they are brilliant. Cost me $350 and it was worth every penny. Plugged straight into the CB loom and have gone to total loss now too. Just need to optimise the curve. I think I need a dyno for that though.

[F5 Dave]

Pammy is coming over to NZ soon, perhaps you can model the curves off her?

. . . actually maybe not. Must have a daughter by now?

[TZ350]

Rather than stuff around with other ignitions, just buy an ignitech. I bought one for my CB a month ago and they are brilliant. Cost me $350 and it was worth every penny. Plugged straight into the CB loom and have gone to total loss now too. Just need to optimise the curve. I think I need a dyno for that though.

I had a look and they are good looking units. They only need a battery and trigger.

Ignitech ignitions:- http://www.ignitech.cz/english/aindex.htm

.

[k14]

I had a look and they are good looking units. They only need a battery and trigger.

Ignitech ignitions:- http://www.ignitech.cz/english/aindex.htm

.
Yeah I was slighly apprenhensive due to the fact they were from so far away (Cheq Republic) and not renowned for their electrical engineering prowess, but haven't had one problem with it. You need a bit of mechanical/electrical knowledge to setup but the documentation is great and its quite straight forward. Only problem is their english isn't spectacular so if you have some questions it may be hard to get an answer.

[TZ350]

Personally, I find the somewhat messier (but easier to read) method of starting with an old set of cases (crank as well) and adapting a inlet from a garden hose along with compressed air (via a sensitive pressure regulator).

I am of the opinion that since you have the dish in your piston, you should create a pattern that utilises that to your advantage (as far as the rear boost port is concerned)

BUT, you must make a clear cylinder head to the same specs as your alumnium one,(then spend the afternoon polishing it so you can see through it, because don't forget, your cylinder head is part of the system.....you can't get a good idea of your scavenge pattern with a flat dish!:no:


One word of advise, to save time, when you change angles (particularly on the boost port/secondary transfer area), use a "hot melt glue gun" as a filler material, just before it cools, using a surgeons rubber glove, with you finger dipped in water/dishwashing liquid smooth it out to somewhere near the angle you want. You can change the angle to where you need by using a flat skinny blade slightly heated.

It really quick, cheap, and no problem if you stuff it up.

When you get what you want, you can later replicate it with a good quality devcon filler.



Interesting posts, good read and info. First step is to make a clear cylinder head.

.

[TZ350]

Yes I've had different settings with different heads when trying out things (often with no appreciable change in performance, sometimes with).

The difference in ignition timing between 16 and 26 degrees on the ESE engines seems huge but the power difference was small only a HP and a bit, about 10% at best.

Actually 10% is quit a bit I suppose.

.

[SS90]

The difference in ignition timing between 16 and 26 degrees on the ESE engines seems huge but the power difference was small only a HP and a bit, about 10% at best.

Actually 10% is quit a bit I suppose.

.

I have been working with my own ignition since November last year, and found the results/power gains to be quite varied.

I was told previously that if I took an existing "well tuned engine" (say, 24PS or more) and simply fitted an ignition with (for example 8 deg retard) I would get .0001 PS gain. (peak power)

i.e peak power won't increase

That turned out to be quite correct.

What is noticable though is a substantual gain in acceleration from idle up to about 3000RPM (more "bottom end")

Like you have noted, different combustion chambers require different ignition amounts of retard, and there is an element of "suck it and see"

The big advantages (I have found) is drastic reductions in cylinder head temperature.

For example, on a slightly modified cast iron cylinder, at 8000RPM (which is quite high for a road scooter) my current ignition design runs at from 25 deg at idle down to 7Deg BDC at 8000RPM), and works well.

This "test engine" is only a standard 75cc cast iron cylinder with standard head etc, and no expansion chamber.

N4cQIKUxxsE

[TZ350]

.

i.e peak power won't increase

That turned out to be quite correct.

What is noticable though is a substantual gain in acceleration from idle up to about 3000RPM (more "bottom end")

That makes sense, if the static timing was set for peak power then a retarding ignition that retards back to the same point as the original static timing would produce the same peak power.

I had a look at the video, very interesting, better bottom end drive, now thats very interesting. I am not sure how much retard (maybe 15 degrees) I will have. So the plan is to start at about 30 or so and let it retard back to 15/17 as the rev's hit peak torqe. Setting up and checking the torque gain/loss should be quick and easy using a dyno.

.

[SS90]

.

I had a look at the video, very interesting, better bottom end drive, now thats very interesting. I am not sure how much retard (maybe 15 degrees) I will have. So the plan is to start at about 30 and let it retard back to 15 as it hits peak torqe.

.

The amount you need seem to vary drastically from engine to engine. (Cylinder head design, exhaust etc)

I can't remember where I found the attached file, but it is a good example of what is considered a "basic curve"

From memory it was using a CR125 (I think)

Personally I have found that, with a good expansion chamber (and suitable head) around 8 deg before TDC at 8000 RPM seems to work,

for anything higher revving, it would be suitable to advance back to 12deg (or so), then back down to (perhaps) TDC firing at 13,000RPM (or even a few deg after TDC) which will give more over rev, but all that is only applicable to "high end stuff"

AG Bell wrote a good book on ignition curves.

[TZ350]

Thanks for the look at the curves.

I will have to live with whatever the RM curve is in my new ignition but I have been working on my own programable (Jaycar kit) ignition and will be able to change/adjust the curve in that when I get it working.

.

[TZ350]

.

This http://www.geocities.com/a57ngel/moto/CDI.html talks about repairing/modifying a KDX CDI's retard curve, there is also a schematic.

.

[SS90]

Interesting what they end up with as far as curve goes....not too far removed from what I found to be a gain.

At home I have a print out of a map curve of the final set up, I will post that when I get home as a matter of interest.

[SS90]

While this certainly isn't for "high end" performance tuning, this graph represents what I run on a cast iron cylinder that runs up to around 8,000 RPM (which is in reality what most customers need)

It isn't really suitable for an engine that runs to say 10,000 or over, but in reality I don't know of a customer who needs that.

For racing use I have another system that retards from 25 deg idle to 17 deg (and remains there until 12,000)

Strangely, while I expected the second "racing" curve to allow the engine to run cooler (passing the heat on to the pipe), I found the opposite to be true, and while it certainly allowed the engine to over-rev more, I found the cylinder head temperature increased dramatically, which was quite a surprise really, lowering the compression a tad and jetting up solved the problem, and it does make more power (now), but, it was a surprise too see.

It was this experience that the above curve was "found"

Speaking to others here, they had found the same problem.

with a retarding ignition, set up certainly appears to be critical.


I don't recommend the above curve for your engine Teezee, but my experience suggests that retarding from 30 to 17 deg (or thereabouts) is about right for an engine revving harder (above 7,000 RPM)

[ajturbo]

so where is all this leading?

a fire breathing 50cc bucket for sale in NZ?











as usual, i have added volumes of interesting facts for you guys to debate

[TZ350]

Speaking to others here, they had found the same problem.

with a retarding ignition, set up certainly appears to be critical.

I don't recommend the above curve for your engine Teezee, but my experience suggests that retarding from 30 to 17 deg (or thereabouts) is about right for an engine revving harder (above 7,000 RPM)

Thank you for your information. My plan had been to retard more than 17 in fact to about 5 at 11,000. You have given me more to think about. I hope to get to the dyno this week and try the RM125 ignition. I have no idea of its curve but have to start experimenting some where.

I have not made any changes to the bike since it was on the dyno at Johns. Because I want to get a good base line printout with torque/revs from the dyno at Henderson before trying new mods.

As several bikes will be going over I should have time to do a base run then fit the ignition and do a little experimenting after the others have done their runs.

I don't have a nice degree wheel setup like yours and my strobe is not that great at triggering of CDI's either. So a couple of other small w/shop things to fix as well.

But I do have a very good copper head to use if things get too hot though. :laugh:

.

[TZ350]

Thank you for your input AJ.

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[TZ350]

.

"so where is all this leading? a fire breathing 50cc bucket?"

Well you never know AJ, just you wait untill Taupo.

Hopefully there will be three of them if not four from team ESE.

.

[SS90]

My plan had been to retard more than 17 in fact to about 5 at 11,000.


.

That's not too far wrong in my opinion. I have seen dozens of different curves from different manufacturers the last year (original and aftermarket) and read a few (conflicting) claims/statements as well.

It does seem that those sort of numbers you are talking are reasonable, but from my experience the suitable curve is very dependent on the cylinder head/ expansion chamber design.

By that I mean, "one curve is certainly not for all"

I'm guessing you are aware of that.

I have mentioned earlier in this thread, but I feel it is important to remind you that when it comes to selecting the correct curve for your engine, it is (all too easy) to go too retarded right at the top end.

This does give you more overrev, but also has the effect of " locally super heating" the piston crown on the exhaust side, and eroding the crown away on that edge.

The effect is the same as too advanced timing, but the cause is somewhat different.

My experience with this is from a VERY VERY wide exhaust port (bridged), and I guess with your unbridged exhaust it's not so much of a concern, as the flame front is considerably smaller with a narrower exhaust port.

The best tools are the cheapest an EGT sensor and an under plug head temp sensor form a Kartsport shop can give you so much information.

AG Bell wrote a book on ignitions, and he suggested a few curves that are interesting, I am unsure if you can find it on the net, but it may give you some ideas that I missed.

[TZ350]

Haven't found Bell yet but came across this on ignitions. yes its cars and 4-stroke but informative nevertheless.

http://www.max-boost.co.uk/max-boost/ignition_deeper.htm

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[TZ350]

The best tools are the cheapest an EGT sensor and an under plug head temp sensor form a Kartsport shop can give you so much information.


We have been having some success with developing a data logging system for our buckets. We use a new to the market Track Day system http://www.xtracing.com/en/gpxpro/features.php and have made a small instrumentation interface so we can log CHT and EGT temperatures.

The GPX can be wired into the existing wiring of a track day or road bike but for an outright racer with little more than a magneto ignition the GPX neads some interfacing system to pickup revs, temps etc.

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[Chambers]

Latest addition to Team ESE's stable of bikes. A 9Hp 3.81ft/lb RG50.

Brought of Trademe, the bike looks very competently put together. The story has it that some girl who was very keen on Buckets, raced this bike about 6-8 years ago then moved to Australia leaving it behind in some shop at Tirau. It was obviously very well cared for.

Pumped up the tyres, changed the oil and water, cleaned the carb, fresh fuel a little push and ZOooooooom ZOooooooom.

Over to the dyno.......9hp and Bob's your uncle.

.

[Buckets4Me]

is that all you did today ????? :scooter:

[TZ350]

.

Headed over to the dyno today, turns out that Chambers has got himself a real neat little 9hp RG50 for F5.

And I managed to get a good baseline run on my GP125. I had not changed anything since the first lot of dyno runs we did at Johns where we only got Hp vs Road Speed. Now I have a proper hp/revs and torqe curve printout.

My base line is 20.6hp at 11,000rpm and 10.3ft/lb with a long flat torque curve.

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[TZ350]

.

Ned Kelly did not have such a good day.

Pic-1 Ned Kellys 16rwhp Easter dyno run which falls off badly compared to Chambers Pic-2.

Pic-2 Chambers 18rwhp Easter Dyno run, motor, chamber, ignition timing essentially the same as Ned Kellys.

We surmised that Ned Kellys was over compressed compared to Chambers engine and this was causing the flattening of the torque curve at higher revs.

Pic-3 Top line is with the compression reduced, a loss of 0.5 hp compared to Easter. Next we surmised that the ignition might be over advanced so we knocked it back to 20 degrees, second line.

Chambers has a fixed point ignition and now we are thinking that the Kawasaki Motor Cross ignition unit that Ned Kelly has goes into heavy retard over 8,000 rpm. But we are handycaped by having a timing light that can't be used over 6,000 rpm so we realy don't know how any of the ignitions are behaving when they are "On the Pipe", at 8,000rpm or more.

Ned Kellys engine runs real hot compaired to Chambers and mine runs realy cool with the head, measured after the third 20hp run and as close to the plug as possible at 50-60 degrees and deep in the barrel between the top two fins at 70 degrees. So I have plenty of cooling capacity left.

The bright spot for Ned Kelly was the realisation that he has been peddling a bike down on power (15-16rwhp) and keeping up with the fast boys. So his riding is pretty good.

Pic-4 My 20rwhp base line run. Now I can get on with my planed mods and exploring those suggested by SS90, Thomas and the others on this thread.

Many thanks to Gavin at Henderson Yamaha for his expert handling of the dyno.

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[Chambers]

Have noticed TZed 20.66 RWHP @ 10.34 Max Torque, Chambers 18.63 RWHP @ 10.44 Max Torque slightly more torque and 2 hp down.
Yeah I would be happy in Ned Kellys shoes he has the handling and will get the HP Im sure the ignition is the problem, Ive got everything crossed that I can get around the corners at more than walking pace with the work done on the front end, still not sure about the back. Go the RG top buy

[SS90]

I recon Chambers engine could be the go, if he can keep that same curve shape and just gain 2 HP I am of the opinion it would be on of the most rideable (High powered) buckets around..... maybe even leave the engine alone and just change the pipe and ignition?

My experience is that it's quite hard to get a nice long spread of peak power like that.

Also, just looking at the roughness of your curve (for the RG fiddy), there is a good chance that your chain is either too tight or knackered, might be worth a look!
:scooter::scooter:

[TZ350]

.

Also, just looking at the roughness of your curve (for the RG fiddy), there is a good chance that your chain is either too tight or knackered, might be worth a look!
:scooter::scooter:

.

Thanks for the tip, checked it this morning but all Ok. The bike is in pretty good condition.

It was just a quick once over on the dyno we didn't want to change the wheel base setup as we were in the middle of working on the 125's and I don't think the RG50's back wheel was sitting in an ideal position on the roller as it is just a bit shorter in the wheel base. I thought it might have been just trying to climb to the top of the roller, it was bouncing a bit and pulling on the tie downs.

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[Anakist]

Hey guys,

Just read the entire thread. Wow what a lot of info. TZ350: There is a lot of information about the heat dissipation of various materials used in computer heat sinks (full aluminium, aluminium with a copper slug, full copper etc), around. Here is a start. http://www.heatsink-guide.com/

The prevailing wisdom is copper is very good at absorbing and dissapating the heat (through the whole heatsink), but not so good at shedding it to the air; Aluminium is much better at shedding it to the air, but not as good at absorbing and dissipating it. Hence the move to copper slugs (contacting the heat source) pressed (IIRC) into aluminium coolers.

We have since moved to heat pipe coolers, but the still use copper bases and pipes, and aluminium fins. This is all done with low pressure, high velocity air.

James

[F5 Dave]

With the 50 on typical Dynojet you need to make some sort of spacer, few blocks of wood in a pinch. That is revving pretty high, the crank may(will) not last if you under gear it & let it spin out there too long.

[TZ350]

Practice on Saturday. http://www.flickr.com/photos/dty1/sets/72157621987309122/

Racing from Sunday. http://www.flickr.com/photos/dty1/sets/72157621989269542/

Other Motorcycle Racing pictures from Damion. http://www.flickr.com/photos/dty1/collections/72157600077237955/
There is no copyright and they can all be downloded.

Team ESE's No 14 (TZzz GP125) riden by Dave M went like a cut cat and was possibly the fastest bike in a straight line. Dave M rode like a demon but the handling and power delivery made it very hard work for him. The fields were dominated by 4-strokes, mostly FXR's and CB125T's with their broad power bands and easy drive out of the corners but Dave M pretty much dealt to them. It wasn't pretty but his style sure was effective (and brave).

But like SS90 says, its time to develop a broader power delivery like Chambers has. Now that I have my base line dyno run I can get into it. And it looks like I need to do some serious work on the suspension too.

.

[F5 Dave]

How is that collarbone healing up?

[TZ350]

Getting there, but not game to race again for a while but certainly plan to be riding at Taupo. How are you going?

.

[TZ350]

That is revving pretty high, the crank may(will) not last if you under gear it & let it spin out there too long.

Yep the crank expired Sunday. :crybaby:

.

[F5 Dave]

Oh, sorry to jinx it (perhaps to the minute if it expired at post time of 10:48?), but as you know 2 strokes that sit for ages are a problem, big end could easily have had some rust forming that strips away the plating when used in anger. I'd be tempted to add a couple of degrees to the baffle to cut the power off earlier (didn't even see if it had a proper pipe).

I'm hoping to be able to ride again in September, maybe race Oct.

[TZ350]

but as you know 2 strokes that sit for ages are a problem, big end could easily have had some rust forming that strips away the plating when used in anger.

It had sat for quite a while. barrel/piston is ok and the porting work looks very professional. The rod was the old no slots kind so the replacement will have slots and better oilling. Thanks for the tip about the baffel cone. The pipe is home made but not of the standard of the rest of the bike.

I have a GP125 pipe to make too and another to design and make, allways more projects than time.

Have fitted and run the GP125 with a retarding RM125 ignition now (last night) so of to the dyno again to dial it in, more $$$$$.

Glad to hear you are healing up, :doctor: it has taken such a long time.

.

[F5 Dave]

Yeah, no real progress until they put the plate in. Still should be good now.

[TZ350]

.

Measuring the balance factor of our Suzuki GP125,s

The round bar is very nearly as good as knife edges.

Pic-1 Finding the counter balance by hanging washers of a hook attached to the conrod.

Pic-2 Determining the mass "C" of the counter balance.

Pic-3 Determining the mass "R" of the reciprocating weight.

The balance factor B = C counter balance mass divided by R reciprocating mass.

The balance factor is.......B = C / R

As measured by me, it turns out that the balance factor of:-

A standard Suzuki GP125 is 69%

A Standard Suzuki GP100 is 76%

A GP with alloy plugs in the counter balance holes becomes 58% for the 100 and 52% for the 125.

When we recently dyno'ed two of our bikes with cranks that had the same 69% balance factors. The RS frame vibrated much more than the original GP frame did.

For us this supported the notion that there is no one correct balance factor, as the right balance factor is the one that works with the frame that the motor is mounted in.

I think it was SS90 that said that the balance factor that works best in a high output 2-stroke will tend towards 50% as the rev's go up. And we found that, that pretty much happened. When we put alloy plugs in the crank balance holes to raise the primary compression ratio. As an unintended consequence the balance factors changed and become less 58-52% and the engines became noticeably smother at higher rpm.

I asked Thomas about this and he said that motors with a wider spread of power and that are operated over a wider rev range like the std GP engine tended to have a higher balance factor than ones with a narrower power band like our hotted up engines. That made sense when you look at the Kawasaki 250 & 500 4-stroke MX bikes that have a BF of 60% and the big 4-Stroke cruisers & sport bikes at 70+ %.

It seems that the wider the rev range the motor is going to be operating over the higher the suitable balance factor will be. Its easy to relate this to the Kawasaki 4-stroke 250 Mx bike, same revs but wider power band, and a BF of 60%.

I have a Honda RS125 crank to look at next, I suspect it will be 50% but for different reasons.

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving. http://www.scribd.com/doc/15392252/Tuning-for-Speed-P-E-Irving-1965-Tuning-Racing-Motorcycle-Engines

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

The balance factor is C / R

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[Brian d marge]

How I balance my engines

from top of head

There is the point of change in motion , hard to determine , geometric ot moment of Inertia

anyway the wieght is slightly different , as the position is slightly different

So i machine up a lead weight that fits around the crank pin as close to the centre line of the pin as possible ( as the mass acts around the pin ) even that is a bit big as the mass of the lead wieght is away from the centre line ,,,of the crank pin

then press up the assembly run on knife edges ( i made a jig using bearings , to try and reduce friction loads ....) and it should come to rest in a different spot after the lightest of touches

thats just the way I did it

Stephen

[k14]

I have a Honda RS125 crank to look at next, I suspect it will be 50% but for different reasons.
Can you work the balance factor out for the RS125 by just weighing the parts of the crank (as you did in the above post) because it has a separate countershaft? Or do you have to weigh the countershaft too?

[TZ350]

Can you work the balance factor out for the RS125 by just weighing the parts of the crank (as you did in the above post) because it has a separate countershaft? Or do you have to weigh the countershaft too?

I was able to weigh the RS crank the same way and the crank itself came out at 50%. The counter balance also looks to represent 50%.

I don't have all the RS here but after looking at the H100. The way I think it works on the RS is that the counterbalance spins twice as fast as the crank.

I said the counter balance "represents 50%" as I don’t think it weighs 50% but because it spins twice as fast as the crank its inertial mass becomes 50% as it spins around.

This allows the counter balance to work with the crank top and bottom to cancel out the piston and then it cancels out the counter weight of the crank mid stroke twice a revolution.

So it goes something like this.

Top:- Cranks 50% plus Balance Shafts 50% going down together cancels the Pistons 100% coming up.

Mid going down:- Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions.

Bottom:- Cranks 50% plus Balance Shafts 50% coming up together cancels the Pistons 100% going down.

Mid going up:- Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions again.

To do this the Balance Shaft has to rotate twice as fast as the crank.

So in theory you get a 100% balancing of the engine but really its just a bit of clever push and shove. As the crank is still 50% out of balance and when it pushes side ways the counter balance shoves it back and then twice a revolution the two of them gang up on the piston and pull it back.

It looks like the engine is balanced but there are really a lot of stresses going on inside.

I am not sure how you would go about matching the counter balance shaft to the crankshaft without making some comparitive weight measurements and doing some maths that takes account of changes in inertial mass with changes in rpm as it would not be a simple 50/50 weight thing for the whole rev range.

As the inertial mass of the counter balance shaft will change more than the crankshaft does with changes in rpm. So I guess you tune the weight of the counter balance shaft to work best in the rev range you want to use.

The balance factor of the RS crank is C/R = 50% of the reciprocating mass.

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[TZ350]

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BMEP introducing some Science to comparing comparative engine performances.

Brake Mean Effective Pressure....Engineering Term & Method for Comparing Different Engines

You can take the performance of say a 125cc Vespa and compare its performance to any other engine whether they are 4-stroke, 2-stroke, supercharged, turbo charged, Diesel, petrol, nitro burning dragster and get a clear idea of whos engine is performing best.

BMEP-PSI = Average Cylinder Pressure in PSI

Two Stroke -- BMEP = HP x 6500 / L x RPM

Four Stroke -- BMEP = HP x 13000 / L x RPM

L = Displacement in Litres (80 cc = .08 Litres) (700 cc = .7 Litres)

So 27.1*6500/0.125*7800 = 180.7

BMEP of a 27.1hp 125 at 7800rpm is 181psi.

BMEP can be used to evaluate power claims be it at 7500rpm or 14,000 and 4 or 2-stroke.

Most air cooled 2-stroke engines will be lucky to better 135psi and water cooled 160 or so. A Honda RS is about 160 and F1 4-stroke race engines manage a bit over 200. So by doing the numbers on your engine (or any engine) you can get an idea wher your at in the development stakes.

An explanation of the expansion chamber design process proposed by Gordon Blair.
http://members.bellatlantic.net/~vze2p5sj/modelengines/expcham.htm

A very through treatment of 4-stroke engine design fundamentals by Gordon Blair. http://www.profblairandassociates.com/pdfs/Back_to_basics.pdf

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[bucketracer]

Something for you TZ, I went looking for references to blowdown degrees required but got side tracked by this article on measuring ports, and I was particularly impressed by how they measured port angles.

www.kartweb.com/TechArt/2Stroke/chapter2.doc

[Brian d marge]

The BMEP in my Enfield is around the 90 to 125 psi cant remember off top of head

the problem is the the fuel conversion efficiency , modern cars are up round the 30 % my Enfield is around the 16 %

Then there's the heat and control of ...........

Stephen

[TZ350]

Well that was fun, an afternoon on the dyno with Gavin from Henderson motorcycles dialing in the RM retarding ignition. The idea was to have the ignition over advanced in the lower revs to pickup some extra torque and then retard back for max power as the revs went up.

Spent a happy couple of hours finding the sweet spot in the retard curve. Went about this carefully 2 deg at a time until we had maximized the power output. Interestingly again as the retarding ignition was dialed in I had to lean it out on the main jet, to get best power.

Turned out to be a total disappointment, but I really should not have been surprised. Especially as after a bit of thought I had started to suspect that an engine that originally got fatter and broader as its over advanced fixed ignition was retarded would not respond well to another over advanced ignition.

As it turned out the power/torque curve with the retarding ignition was worse in every way compared to the fixed ignition except at over rev. I guess the amount of retard (about 15deg) with this ignition is too much to be able to get it right at both ends of the rev range.

The one exciting point is the 500rpm over rev at the top. I will try this retarding idea again with a unit that has less retard, maybe 5-7deg. Didn't SS90 say that less retard than 15 and more like 5-7deg might be better? he could be right. The RM unit is probably better suited to one of the other ESE bikes that still has the large open no squish head like the early RM did.

Pic-1 Retarding ignition, curve "R"

What I would like is the fixed ignition curve to 10,500revs then have the retard kick in for over rev to 12,000.

.

[k14]

Save the stuffing around and go buy one of these http://www.ignitech.cz/english/aindex.htm

Best money I have spent on my CB. Still haven't had it on a dyno yet so have only been changing the timing by my own feelings. I can keep up with most of the FXR's down the straight on the CB now. Something I couldn't even remotely manage with the standard CDI.

[sonic_v]

Well that was fun, an afternoon on the dyno with Gavin from Henderson motorcycles dialing in the RM retarding ignition. The idea was to have the ignition over advanced in the lower revs to pickup some extra torque and then retard back for max power as the revs went up.

Spent a happy couple of hours finding the sweet spot in the retard curve. Went about this carefully 2 deg at a time until we had maximized the power output. Interestingly again as the retarding ignition was dialed in I had to lean it out on the main jet, to get best power.

Turned out to be a total disappointment, but I really should not have been surprised. Especially as after a bit of thought I had started to suspect that an engine that originally got fatter and broader as its over advanced fixed ignition was retarded would not respond well to another over advanced ignition.

As it turned out the power/torque curve with the retarding ignition was worse in every way compared to the fixed ignition except at over rev. I guess the amount of retard (about 15deg) with this ignition is too much to be able to get it right at both ends of the rev range.

The one exciting point is the 500rpm over rev at the top. I will try this retarding idea again with a unit that has less retard, maybe 5-7deg. Didn't SS90 say that less retard than 15 and more like 5-7deg might be better? he could be right. The RM unit is probably better suited to one of the other ESE bikes that still has the large open no squish head like the early RM did.

Pic-1 Retarding ignition, curve "R"

What I would like is the fixed ignition curve to 10,500revs then have the retard kick in for over rev to 12,000.

.


I would not give up on your ignition just yet. I usually find that the fitment of a retarding ignition usually requires a different exhaust pipe, particularly if the original is a touch on the short side. It strikes me that your engine is now working at revs that are too high for the exhaust port time area. A longer pipe that better matches your exhaust port time area and the new peak power ignition advance could provide big gains.

Would be interested to see your exhaust duration and exhaust system tuned length (piston to end of reverse cone). In fact whilst you are at it you should calculate your exhaust port time area.

I have used the rm80 ignition on different applications and it has worked well. However, at peak power speed have uasually had an advance of about 7 degrees. This requires the exhaust to be spot on to work. Judging by your description of the rm125 ignition, it sounds as if the two might be very similar.

[Brian d marge]

May I make another suggestion !

I m not sure of the bike, and have a little bit of an idea of the tracks you run on ( would they be the same as Ruapuna kart track)

anyway that Dyno run is peaking at 12? do you even get to 12 on the tracks you run at ? , its the haul out of the corners

Id be moving that peak down to where you actually spend most of the time... and thermal efficiency

2 strokes have a nice chamber, but if the flow is separating anywhere along the path or out the exhaust, even separating IN the exhaust

your flow, what ever will get the mixture in there is looking good .... but if it isn't converted. its wasted, what are your Mach numbers for those ports? ALL ports , crankcase , transfer , inlet ?

Me I bumped up my BMEP and now have a mighty heat issue and its a toughy !

i am Enjoying this thread , but don't spend too much , that is real easy to do ,,only to say ,,,ooopps ( I think you know that ! ,,,,I am still too dumb to realise ,,,so continue to waste far too much money ,,,,,though it is getting better as I improve my simulation skills )

Stephen

[ajturbo]

May I make another suggestion !

I m not sure of the bike, and have a little bit of an idea of the tracks you run on ( would they be the same as Ruapuna kart track)

anyway that Dyno run is peaking at 12? do you even get to 12 on the tracks you run at ? , its the haul out of the corners

Id be moving that peak down to where you actually spend most of the time... and thermal efficiency

2 strokes have a nice chamber, but if the flow is separating anywhere along the path or out the exhaust, even separating IN the exhaust

your flow, what ever will get the mixture in there is looking good .... but if it isn't converted. its wasted, what are your Mach numbers for those ports? ALL ports , crankcase , transfer , inlet ?

Me I bumped up my BMEP and now have a mighty heat issue and its a toughy !

i am Enjoying this thread , but don't spend too much , that is real easy to do ,,only to say ,,,ooopps ( I think you know that ! ,,,,I am still too dumb to realise ,,,so continue to waste far too much money ,,,,,though it is getting better as I improve my simulation skills )

Stephen
so your talking about an engine that pulls like my buell (or a school boy if your like that) from way... way down low?...

[F5 Dave]

What I'd be concerned about is that the retarded ignition gets the revs pretty high for an old suzi crank. But clearly there would be a nice gain in a curve closer suited between the two.

[bucketracer]

Another handy rule of thumb for those who find working with Port-Time-Area irksome.

Bells book has some handy rules of thumb for port timings for the Ex, In and Trans but nothing for "Blow-down" the period between exhaust opening and the transfers opening.

I found this handy rule of thumb for blow-down in Gordon Blair's book "The Basic Design of Two-Strokes", and it is, that the number of degrees of crank rotation for sufficient blow-down time will be around the degrees of crank rotation it takes for the piston to uncover a 1/4 of the exhaust port window area.

So for wide bridged ports and ex ports with supplementary side ports the number of degrees required for blow-down will be less than for narrower higher single exhaust ports.

.

[TZ350]

Thanks for that Bucket, if you can find it on the net I would love a link to it.

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[bucketracer]

Will see what I can find.