Some of the better Links. Posted here together on page 80 so they can be easily found.
Came across this on ignitions. yes its cars and 4-stroke but informative nevertheless.
http://www.max-boost.co.uk/max-boost...ion_deeper.htm
Gordon Jennings:- http://www.vintagesleds.com/library/...20Handbook.pdf
An assortment of Gennings Articles:- http://www.edj.net/2stroke/jennings
Graham Bell:- http://www.kreidler.nl/artikelen/per...raham-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/T...rcycle-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_in...okeengine.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/teamsparr...rheadsv2_3.xls
Simulation video clips of 2-stroke scavenging:-
http://video.google.com/videosearch?...um=4&ct=title#
A catalog search engine, pistons, rod kits etc.
http://www.who-sells-it.com/r/mahle-...-2-stroke.html
Using only one ring:- http://www.vintagesleds.com/library/...ing_effect.pdf
The effects of higher compression ratios in a 2-stroke:-
http://www.vintagesleds.com/library/...ompression.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/t5...organ/head.htm
Dispelling 2-stroke tuning myths:- www.fatbaq.com/RS125_dispellingmyths.doc
Rate of Fuel Burn:- http://www.factorypro.com/tech_tunin..._vs_power.html
Reading Plugs:- http://www.dragstuff.com/techarticle...ark-plugs.html
Engine formulas:- http://members.bellatlantic.net/~vze...es/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....ge=squish1.htm
http://www.aircooled-rd.com/default....ge=squish2.htm
http://www.aircooled-rd.com/default....ge=squish3.htm
A preview of Kevin Camerons book “Sportbike Performance Handbook”:-
http://books.google.co.nz/books?id=L...esult#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/...ase_volume.pdf
Piston pin offset and what it means for extra power:-
http://www.motorcycleproject.com/mot...ws-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
.
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/...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
.
OOOOOOOOOOooo
AHHHHHHHHHhhhhhhhhhhhh... that is so cool!!!
what a ride so far!!!!
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.
Don't you look at my accountant.
He's the only one I've got.
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.
.
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!![]()
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.
.
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!
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.
Don't you look at my accountant.
He's the only one I've got.
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.
.
Yes I've had different settings with different heads when trying out things (often with no appreciable change in performance, sometimes with).
Don't you look at my accountant.
He's the only one I've got.
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.
Pammy is coming over to NZ soon, perhaps you can model the curves off her?
. . . actually maybe not. Must have a daughter by now?
Don't you look at my accountant.
He's the only one I've got.
There are currently 39 users browsing this thread. (0 members and 39 guests)
Bookmarks