ESE's works engine tuner

[SwePatrick]

Patrick im sure a small 2t would do fine at 18:1 but what about with 90.5mm piston ? unfortunately I have no test dyno to see if it makes the same power at lower comp ratios.

The piston can take it, the thing to worry about is small end bearing.
To gain data about this, have a look at those hardcore dragracing banshees in the USA.

rgds.

[peewee]

patrick i dont pay any attention to the usa banshee guys. i think most of them are a bunch of rubes . alot of what they do i dont agree with and their 2t ideaology seems to be stuck in 1980. besides that, i find frits, wobbly, jan and everyone else around here to be far more knowledgable

[wobbly]

The loads imposed by compression forces are a whole order of magnitude less than those of the inertial stress on the piston/rod/bearings etc from
being stopped at TDC/BDC.
I have said this before - you could happily double the power output of an engine and see no evidence of any extra " load " on the working parts as long as the rpm
wasnt increased.
The exception is of course the gear tooth loading, and maybe long term bore/ring wear from the higher gas expansion pressure.

The same small end bearings as are used in a Banshee can be had with silver plated cages if that is a reliability concern, but if they fail it would be because
they are shoving a massive 75mm piston around, when the original design was for a tiny 54mm - 125 sized cylinder.
And I would bet the house on the fact that the failures would be down to the onset of detonation - again,the shock loading of this uncontrolled combustion far exceeds
any forces imposed by a controlled ( relatively slow ) spark ignited gas burn.

As far as compression is concerned in big bore sizes, it has been proven time and again that smaller pistons can be pushed way harder.
19:1 was used with Elf 124 octane in 125/250 GP racing, and is fine with Methanol at over 130 effective octane when running over rich.
In a huge bore i would go 15.5,maybe 16.5 for drag racing where the run time is super short.
But to use these big compression's its super important to have effective squish working and a very cold plug,with water being used properly to cool the threads.
To be sure, the heat released into the pipe is lower, due to a load of unburnt fuel being dumped, but the combustion temp is high that is generating the higher gas pressure
to make more power.

[F5 Dave]

Thoughts on my plated bore hone question a couple pages back??

[wobbly]

Diamond as such isn't really needed, you can hone a coated bore with normal stones easily enough.
The real issue is that " proper " Sunnen honing heads force the stones dead true to the vertical axis of the machine, thus can remove taper or ovality.
This assumes then of course that the bottom deck is true to the bore - not an assumption you should make of course.

The honing pattern is hugely variable depending upon the bore and ring face material.
I recently dyno tested a Vortex ROK engine, the same as the one I did during analysis for NZ Kartsports replacement midget/junior category.
The popular myth was that they never go as well when a new piston is fitted, so to be quick you must have a brand new engine just run in.
Anyway the short of the story is that after testing the actual Ra of a new bore,I tried various surface courseness, and hatch patterns.
The stock new surface Ra from the factory is very fine, but has a huge crosshatch pattern almost 90* and using a $25, 3 stone small engine hone from Supercheap
I could replicate this in 30 seconds with a battery drill running real slow.
Result - same power everywhere within a 1/10th, worst result was from another engine man who had a very course surface with very shallow hatch - 0.8 Hp down ( nearly 10% )
Vortex are no fuckwits it would seem,some engine builders are.

[SwePatrick]

patrick i dont pay any attention to the usa banshee guys. i think most of them are a bunch of rubes . alot of what they do i dont agree with and their 2t ideaology seems to be stuck in 1980. besides that, i find frits, wobbly, jan and everyone else around here to be far more knowledgable

Yes, they might be, but you can´t deny that those bansheeguys actually got a lot of power in their rides?
To be a really good tuner one need to look over the fence also.

[Grumph]

Diamond as such isn't really needed, you can hone a coated bore with normal stones easily enough.
The real issue is that " proper " Sunnen honing heads force the stones dead true to the vertical axis of the machine, thus can remove taper or ovality.
This assumes then of course that the bottom deck is true to the bore - not an assumption you should make of course.

The honing pattern is hugely variable depending upon the bore and ring face material.
I recently dyno tested a Vortex ROK engine, the same as the one I did during analysis for NZ Kartsports replacement midget/junior category.
The popular myth was that they never go as well when a new piston is fitted, so to be quick you must have a brand new engine just run in.
Anyway the short of the story is that after testing the actual Ra of a new bore,I tried various surface courseness, and hatch patterns.
The stock new surface Ra from the factory is very fine, but has a huge crosshatch pattern almost 90* and using a $25, 3 stone small engine hone from Supercheap
I could replicate this in 30 seconds with a battery drill running real slow.
Result - same power everywhere within a 1/10th, worst result was from another engine man who had a very course surface with very shallow hatch - 0.8 Hp down ( nearly 10% )
Vortex are no fuckwits it would seem,some engine builders are.

Never worked on one of them...what's the ring ?

Those small engine hones have saved my bacon a couple of times. Good value.

[Flettner]

Ok, It's me, go round in circles with projects:
On the weekend I did a trail ride, not unlike other weekends but this one was relatively open and fast. Most upset as I couldn't hold off the 450's. So it is time!
This 360 rotary valve twostroke engine has sat on the shelf for several years now after I came up against a problem with the valve / throttle assembly. I'm assuming if I made the throttle gate a two piece opening from both sides I could have the valve opening at approx BDC on the pipe and after the transfers close at lower off pipe running. To be fair I think Frits already suggested this. The other side (close side) gate will move with revs / throttle as it dose now with my 350 F9. The cylinder already is cast to accept in cylinder injectors. I guess I'm asking is this a fair assumption.

[Grumph]

Ok, It's me, go round in circles with projects:
On the weekend I did a trail ride, not unlike other weekends but this one was relatively open and fast. Most upset as I couldn't hold off the 450's. So it is time!
This 360 rotary valve twostroke engine has sat on the shelf for several years now after I came up against a problem with the valve / throttle assembly. I'm assuming if I made the throttle gate a two piece opening from both sides I could have the valve opening at approx BDC on the pipe and after the transfers close at lower off pipe running. To be fair I think Frits already suggested this. The other side (close side) gate will move with revs / throttle as it dose now with my 350 F9. The cylinder already is cast to accept in cylinder injectors. I guess I'm asking is this a fair assumption.

I'd always wondered about using a doubled rotary valve the two pieces of which could move relative to each other to vary timing - possibly using a centrifugal mechanism. Your idea (as i understand it) of moving the port opening in the outer cover is probably easier.
But how much difference does varying the valve timing actually make ?
I have also had it suggested to me that it's possible to use both a reed and a rotary valve on the same motor. Rotary timing optimum for peak HP - with the holes filled in by the reed valved "conventional" inlet...Two carbs so KISS goes out the window.
Yes, Husa I do know about the Kawasaki system - KIPS is it ? Additional small reed inlets off the disc cavity.

[husaberg]

I'd always wondered about using a doubled rotary valve the two pieces of which could move relative to each other to vary timing - possibly using a centrifugal mechanism. Your idea (as i understand it) of moving the port opening in the outer cover is probably easier.
But how much difference does varying the valve timing actually make ?
I have also had it suggested to me that it's possible to use both a reed and a rotary valve on the same motor. Rotary timing optimum for peak HP - with the holes filled in by the reed valved "conventional" inlet...Two carbs so KISS goes out the window.
Yes, Husa I do know about the Kawasaki system - KIPS is it ? Additional small reed inlets off the disc cavity.

Not what i was going to say,. lol
but years ago i post a dyno graph that shows the effect of just retarding the disc timing itself its very telling. it appears to be a true something for nothing curve extender
Give me a bit of time to find it.
Note the duration of the disc opening in the graph is the same for both examples only the opening and closing timings are different.

[F5 Dave]

Thanks Wob. Does raise the odd question more. . , just trying to formulate an intelligent one,. . .
So were gp teams honing barrels at the track back in the day, assuming they didn't have an endless supply of new barrels?
Are some plating finishes more tolerant?

[Flettner]

Grumph, the rotary valve timing makes a huge difference as I've found on my F9, but I'm only adjusting the shut side. Approx 55 degrees through to approx 78 degrees. I've always understood the open side did not matter so much but once again because i can I'd like to adjust the open as well. On a standard Kawasaki the valve opens after the transfers shut but with 'cut' valves I saw the port open before the transfers shut and I guess on the pipe that's a good thing but how much? I thought I read somewhere here that the transfer event was largely over by BDC , is that so? If so, on the pipe I might as well open the RV as soon as possible.

Real reason. I painted myself into a corner with the throttle gib not having enough room to be able to slide the whole way across the port so if I have another from the other side, mechanical problem solved.

I made a Kawasaki 100, (a 100 years ago) that had both RV and a reed valve in the back of the crank case. Two carbs, standard RV and carb with the reed being (RD250?) through a similar carb. Special throttle cable linkage so RV opened before the reed. Original cast iron cylinder was the blockage though, even being water cooled and ported, transfers were just not big enough, luckily I don't have to put up with that bullshit now.

[TZ350]

Grumph, the rotary valve timing makes a huge difference as I've found on my F9, but I'm only adjusting the shut side. On a standard Kawasaki the valve opens after the transfers shut but with 'cut' valves I saw the port open before the transfers shut and I guess on the pipe that's a good thing but how much? I thought I read somewhere here that the transfer event was largely over by BDC , is that so? If so, on the pipe I might as well open the RV as soon as possible.

From memory.

The most effective suction effect of the pipe needs to be centered around BDC. To get the widest power spread, before at lower rpm and swinging through BDC at max power to after BDC for over rev.

The rotary valve opening point needs to open later and later as the rpm increases so as to give the pipe time to suck up the higher crankcase pressure created at BDC instead of it escaping out the inlet tract.

As the rpm increases the inlet can be closed later and later to take advantage of the increasing energy in the ram effect of the inlet tract.

So if you have enough inlet open duration for the power you want then the hot ticket for greater power spread might be to swing both sides of the inlet timing in unison so the duration stays the same but the inlet opens and closes earlier at lower rpm and as the rpm increases the inlet opens and closes later and later. A true win win at both ends, opening and closing.

[katinas]

Do you have a video of it running? May we see it?

Hi,

I planned to make new header for pipe (shorter, straighter) before second tests , but Flettner forced me rolling the motorcycle on ice with slicks for videos tests ( cold winter -15C, so If I get sick, I hope Flettner will send me New Zealand honey ).
But failed to attach this video, file is to large, although I select very low resolution

[husaberg]

Hi,

I planned to make new header for pipe (shorter, straighter) before second tests , but Flettner forced me rolling the motorcycle on ice with slicks for videos tests ( cold winter -15C, so If I get sick, I hope Flettner will send me New Zealand honey ).
But failed to attach this video, file is to large, although I select very low resolution

Add to youtube or what ever your preference is then post in a link using the video option
Second row fifth from the right it the icon looks looks film roll.
I am picking you were trying to add it as an image or a file attachement, rather than a video.