ESE's works engine tuner

[F5 Dave]

I'm 70 years old now, so my physics education started about the same time that fire was invented. That came in quite handy if thermodynamics is what you need.
Knowledge? That's simple: it's never enough. No matter what you study, if you're serious about your work, you'll always end up at the boundaries of your knowledge.
Quantum mechanics: I barely follow it; I still hope that one of these days someone will come up with a more elegant approach.

Improving cooling by preventing heat going from duct/flange to the cooling fins?? Yeah, if your goal is to keep the cooling fins cool. But you don't want cool cooling fins, you want all the walls that come into contact with fresh mixture to be cool.
Inserting a pipe in the duct will decrease duct volume and diameter, which is usually a good thing. And the air barrier between the pipe and the original duct will keep the original duct cooler, but it will keep the inserted part of the pipe hotter, which is a very bad thing.
The fact that with this solution the bike comes on the pipe a bit later is an indication that the exhaust gas stays hotter. In itself that is not a bad thing. But the hot inserted part of the pipe will also heat up the washed-through fresh mixture which is bad for power and provokes detonation.

Have to say. I love your turn of phrase.

[Frits Overmars]

Have to say. I love your turn of phrase.

My pleasure Dave. And that's not just a figure of speech; I really like to weave some entertainment into my writing. It came in handy when I made a living as a technical editor and I still enjoy doing it.

Frits, why would then mostly air cooled kart cylinders, like these two, have flanges as closest possible to the cylinder without any fin attached to the flange? Looks to me that they are trying to cool cylinder as much as possible I.e. on a radial positioned fins like here, heat from flange would go directly to transfer ducts if fins attached to. On that cast iron cylinder of mine fins are axial positioned and no fins from flange are connected to the transfers. Looks like two situations and finally getting some answers!

That is right Frano. In those aircooled kart cylinders the exhaust duct was kept as short as possible, so it would pick up as little exhaust gas heat as possible.
There were no fins attached to the flange, simply because there was no place for them. But fins conducting heat from the exhaust duct to the transfer ducts need not be a problem because you can simply make interrupted fins like in my 1955 DKW.


Those kart engines had issues that were completely different from the engines that I've been working with in the past decades. Cooling was a major weakness of course, with their shrunk-in cast-iron sleeves and aircooling. Because of their mediocre cylinder filling, detonation was less of a problem despite their high compression ratio.

Maximum power was not nearly as important as a huge overrev ability. The graph below shows the powercurve of a 100cc world champion with direct drive:
no clutch, no gearbox, just a chain from crankshaft to rear axle. Acceleration out of slow corners was paramount, so because of this direct drive those engines needed a very short gearing. And to avoid being overtaken further up on the straightaway they also needed this huge overrev capacity.

This brings back memories. The first time I got in contact with these direct-drive engines, I immediately saw big opportunities: better port timings, better scavenging angles, better angle.areas, a better pipe, and so on.
It worked: lap after lap my driver managed to overtake two or three competitors on the straightaway. There was just one little problem: he was left standing after every slow and medium-speed corner. And in those days the tracks had more corners than straights. I believe they still do .

The only modification that survived this learning curve, was the brake light switch on the brake pedal, borrowed from a moped. There was no brake light, but the switch cut out the ignition, so the driver could brake and at the same time keep his right foot down: more mixture through the engine, better internal cooling and lubrication, and eliminating the dangerous practice of putting your right hand over the side-mounted rotary carb inlet, also with the intention of providing cooling and lubrication,
and with the risk of getting a finger caught in the chain. I've seen drivers taking off their right glove with a finger tip still inside it.

[Matt@TYGA]

Please excuse my incompetence, but trying to find a post from Jan where he mentioned rod length ratios and what have you. I'm obviously crap at searching this forum as I can find just about everything except what I actually want!! Any help appreciated

Cheers, Matt.

[breezy]

I first tried it on a 50 cc in 1074: more power.
Going from 80 to 85
Then at Aprilia in 1996: more power.
Without varying the crankcase volume.
We went from 112 to 113 and 115, later 118 was tried, still better.
For the RSA we had to lengthen the connecting rod from 115 to 120 to improve inlet flow: more power.
It is mainly due to piston friction I think.
NSU already found this in 1953, piston friction was the main source of friction in their 250 4-stroke engine.
It may be different for a reed valve engine, I have not much experience with these.
But the piston friction loss will, of course, be the same in a reed valve engine.

Of course at BDC there is no difference as you have to adjust the cylinder height!
Maybe it is interesting that with a longer connecting rod I could use higher transfer ports on my 50.
Getting still more power!

The crankcase volume also changes, of course, unless you change the position of the piston pin in the piston, as we did at Aprilia
This can be better or worse....
You can change your crankcase volume in many ways.
But always keep in mind that flow is more important than volume.....
On rotary valve engines I found the bigger the better, within reason of course....
The Aprilia engines had very narrow crank wheels, (16mm) so a very big crankcase volume. About 660cc in TDC
A big crankcase volume makes very long inlet timings necessary.
And big carburetors.

This is probably the reason why reed-valve engines need a smaller crankcase volume.
The reeds 'decide' for themselves when to open...
They need some depression.
And because maximum inlet flow is probably determined by the reed block, big carburetors won't work on a reed-valve engine.
They just slow down the flow in the carburetor, making for a difficult carburetor adjustment.

So I think that a rotary valve engine will always give about 3-4 HP more (125cc) than a reed valve engine.
Because of its unrestricted inlet flow and less pumping losses.

hello, was it this...conrod lengths?

[wobbly]

Matt , the Aprilia ended up with a 120 rod om 54.4 stroke.
Honda had a short 105 for ever , but finally saw some light in the last Aoyama RS250 that had 109.
In karting its still a matter of conjecture , but the shortest is 105 , the longest 115.
TM have 109.8 due to a CNC error 20 years ago.
Depends upon the intake system somewhat in that any RV loves a big case , so long rods make this easy to achieve.
Reeds seem to have a bottom limit of diminishing returns at about 1.3 ratio - any bigger case and you have to use excessively thin petals to get the case Helmholtz
and the reed first mode frequency correct.
Then the reeds start going spastic and you loose any extra power gained from the bigger case reservoir volume.

[Muhr]

The 3D map allows you to take timing out when pulling low/med rpm with little throttle opening.
This is where the engine will deto if running up around 28* in a single curve map.
But 28* is what you want when at low/mid rpm under the pipe , when at full or near full throttle.
This gives way better throttle response.

Thought that I would come back to a side project that we fiddle with to a friend who spends the weekends with Kart-cross. I wondered about experience of ignition systems and you answered unequivocally that Ignitech was the way to go. unfortunately they seem to be very busy, so I chose to go for zeeltronic PDCI-15V with programmable spark power. Hopefully we will not be too disappointed! Otherwise it starts to approach Dyno time !! Will return with results.
If someone has tampered with spark power, I would like to receive some experience.

[peewee]

on Friday I got started welding the ears then the worst possible thing happened. the torch head died and spit water out. probly be seven to ten days before I can have another torch to my house but this time I buyed two heads as a spare so this shit can never happen again. im alittle angry because I could have finished the welding already today

[SwePatrick]

Thought that I would come back to a side project that we fiddle with to a friend who spends the weekends with Kart-cross. I wondered about experience of ignition systems and you answered unequivocally that Ignitech was the way to go. unfortunately they seem to be very busy, so I chose to go for zeeltronic PDCI-15V with programmable spark power. Hopefully we will not be too disappointed! Otherwise it starts to approach Dyno time !! Will return with results.
If someone has tampered with spark power, I would like to receive some experience.

I had an older ignitech system on my machine a while ago, and it was baaad,,, well the coil was or the time loading the coil.
I had a batterycharger running at the same time as my dynopulls, and still it just soaked ampere when i was hitting the throttle, i tried different plugs, no success.
It just wasn´t to be done in my methanol engine, the voltage drop was HUGE during maxtorque and upwards, it was down to 9v.
And it had problems producing power ofcourse, when starting to get some power, it just began to misfire.
My old pvl '458' performed much better.

But i gave ignitech a chance again, i bought a new system from Emot.nl and he has combined the ignitech with a pvl coil.
Now i have no issues what so ever.

Rgds.

[yatasaki]

Frits, while still warm about aircooling, a few right or wrong statements:
Air-cooled cylinder to fit with metal gasket or without gasket,as needed ,under cylinder to improve cooling.
Crankcase to isolate by layer of something to keep mixture as cool as possible.Heat from cylinder then goes to gearcase and oil over the crankcase ( crankshaft will pick some over bearings)
Gearcase to roughen from inner and outer walls: Inner to keep oil longer on the walls, outer to increase cooling area.
Ignition and gearbox covers made from aluminium to mount without or with metal gasket to improve cooling. Oil would do heat transfer to cover when fit with paper gasket but why not both.

[wobbly]

Something TZ350 did that I thought was damn clever - he made a head gasket from copper sheet.
But the sheet extended out way past the head and cylinder fins.
Must have improved air cooling capability dramatically.

[yatasaki]

Copper gasket would be great...if fins are radial (and if not clogging fin-air passage) but in my case are axial

[TZ350]

Air-cooled cylinder to fit with metal gasket or without gasket,as needed ,under cylinder to improve cooling.Crankcase to isolate by layer of something to keep mixture as cool as possible.Heat from cylinder then goes to gearcase and oil over the crankcase ( crankshaft will pick some over bearings).

My experience with isolating the cylinder from the crankcase was that the crankcase/gearbox and oil by them self run very hot. Maybe as much as 80-90 or even 100 deg C in a long race when the water cooled cylinder was only ever at 40-45 deg C.

Next time you run your bike, afterwards feel the flywheel, it will be quite hot. That heat is mostly transmitted out to the flywheel and comes from the crankcase. I think that anything to cool the crankcase would be worth the effort.



Speedpro took the copper head fin idea a step further and made a clutch cover copper gasket/fin that picked up heat from the hot gearbox oil and transmitted it to a large cooling fin on the outside.

[husaberg]

My experience with isolating the cylinder from the crankcase was that the crankcase/gearbox and oil by them self run very hot. Maybe as much as 80-90 or even 100 deg C in a long race when the water cooled cylinder was only ever at 40-45 deg C.

Next time you run your bike, afterwards feel the flywheel, it will be quite hot. That heat is mostly transmitted out to the flywheel and comes from the crankcase. I think that anything to cool the crankcase would be worth the effort.

Speedpro took the copper head fin idea and made a clutch cover copper gasket/fin that picked up heat from the hot oil and transmitted it to a large cooling fin on the outside.

The Kawasaki tandems that ran at Daytona one year had the oil levels lowered to prevent the oil splashing against the inner crankcase. with this mod they held their power longer.
i wonder if a plate kind of like a windage tray that stops the hot oil hitting the inner crank side would help. On bike where you cant water cool the cases.
Along with that Russian ceramic paint emot has on both inner surfaces.

Another GP trick is to run separate oil for the clutch and gearbox just block up the holes between both that is where most of the heat actually comes from or better still make a dry clutch. this way you can run different levels
You have already stopped the friction from running the gears through a trough of oil with your gearbox oil pump set up so only need the oil to touch the bottom of the primary gears
the Kawa tandems They also ran 7 speed gearboxs at Daytona as the rules never said you couldn't that way if the wind changed on the bowl they would still be gear correct.

ps Remember how finned the air cooled Suzuki twins and triples crankcases were. bloody heavy and hard to cast but they did it. i dont think it was just fashion

Greeves t i think used to run a ducted cavity between the bolt up gearbox
Frits posted a pic with the big Germans 50 with the massive weld on fins on the crankcase for some simpson? air cooled class


a lot of Little tings add up.

[yatasaki]

My clutch is ON the crankshaft
Rulebook doesn't allow to weld anything
So engine itself has to look as from factory from outside.
Ok..maybe a bit oversize copper gaskets wouldn't be a problem

[Muhr]

ps Remember how finned the air cooled Suzuki twins and triples crankcases were. bloody heavy and hard to cast but they did it. i dont think it was just fashion


a lot of Little tings add up.

You also have a vortex solution on air-cooled crankcase

https://www.tkart.it/en/magazine/und...16-revolution/