ESE's works engine tuner

[lodgernz]

OK, here's the dyno result (thanks F5Dave) with my new Disc Valve setup on my NSR50, using the same 24mm carb and pipe etc. as with reeds.
The red line is with reeds, the blue line is with the RV.
As Wobbly predicted, closing at 80º has cost top end and over-rev. Surprising similarity with reeds through the mid-range though.

Next move is to cut the disc to get 85º closing, then, depending on that result, 90º closing. I think I'll leave the opening at 135º for now.

[wobbly]

Way back when dyno testing the old Rotax twin at Zipkarts for Hines Superkart,I found that the closing timing of the RV is very
responsive to tiny changes.
The stock timing was 134/86 , and moving the closing out to 88 gave a big result in peak and overev power.
That engine only reved to 13400 max tho, and any more timing simply killed the upper midrange way more than it increased the topend.
Opening ended up at 138 as going any more made it all but impossible to jet correctly with a huge amount of standoff badly affecting the acceleration
both under dyno load and on the track.
So my advice is to cut the blade in only 2* increments at most.

[peewee]

swepatrick a few years ago i had honda that i only used petrol and castor. the engine never failed but i took it apart one day, i think to grind the ports alittle from what i recall. i was suprised to see rust on the iron bore and forming on the crank bearing races. i suspect the castor was attracting moisture. dont forget it might happen to you also

while im thinking of it, does anyone know of a shorty plug thats reasonably priced ? since adding a spacer under the cylinder i cant use a normal plug now. i been using the br9ecm like what some moderm ktm use but theyre 12usd plus freight and theyre only available in resistor type. the owners manual says i should use nonresistor and i already have 5k cap so should i be using nonresistor or what ? unless maybe i could find a non resistor cap somewhere. the cdi-coil is all one unit. electronic stuff isnt my specialty

[lodgernz]

Way back when dyno testing the old Rotax twin at Zipkarts for Hines Superkart,I found that the closing timing of the RV is very
responsive to tiny changes.
The stock timing was 134/86 , and moving the closing out to 88 gave a big result in peak and overev power.
That engine only reved to 13400 max tho, and any more timing simply killed the upper midrange way more than it increased the topend.
Opening ended up at 138 as going any more made it all but impossible to jet correctly with a huge amount of standoff badly affecting the acceleration
both under dyno load and on the track.
So my advice is to cut the blade in only 2* increments at most.

Thanks Wobbly, that's really good info. So, 2º it is then. I suspect there's possibly 2º variation in timing due to belt flex but hopefully consistent under load.

I was very pleased to see that the twisted belt arrangement was completely untroubled by several 14,000+ dyno pulls, including "blipped" down-changes.

[Grumph]

Thanks Wobbly, that's really good info. So, 2º it is then. I suspect there's possibly 2º variation in timing due to belt flex but hopefully consistent under load.

I was very pleased to see that the twisted belt arrangement was completely untroubled by several 14,000+ dyno pulls, including "blipped" down-changes.

Put a strobe on it to see how much the belt moves in use.
On an OHC setup it's horrifying but your little disc is much lower loads.

[Peter1962]

Happy birthday, Frits !

[husaberg]

Put a strobe on it to see how much the belt moves in use.
On an OHC setup it's horrifying but your little disc is much lower loads.

Flettner has mentioned how this quirky wrinkle it could be very useful on a 2t.

Oh yeah happy birthday Frits, your present is under your bed.

[F5 Dave]

What I like is it gained between 9 & 10. Why?!?!. Also it used the same jetting as the reed valve. Was cool to see the belt in action. Like to see a way shorter inlet tract but packaging just doesn't allow.

[sidecar bob]

What I like is it gained between 9 & 10. Why?!?!. Also it used the same jetting as the reed valve. Was cool to see the belt in action. Like to see a way shorter inlet tract but packaging just doesn't allow.

Just loose the disc valve & belt. Apparently shit runs better without them.

[Flettner]

I don't know, but it would seem the sliding rotary valve GIB might be a good thing after all. It works for me. I wonder, what might happen if in conjunction with a variable valve housing, open a port on the opposite side of the crankcase when on the pipe. A 23 / 7 induction of sorts.
With TPI it just needs to be a hole.

[SwePatrick]

swepatrick a few years ago i had honda that i only used petrol and castor. the engine never failed but i took it apart one day, i think to grind the ports alittle from what i recall. i was suprised to see rust on the iron bore and forming on the crank bearing races. i suspect the castor was attracting moisture. dont forget it might happen to you also

while im thinking of it, does anyone know of a shorty plug thats reasonably priced ? since adding a spacer under the cylinder i cant use a normal plug now. i been using the br9ecm like what some moderm ktm use but theyre 12usd plus freight and theyre only available in resistor type. the owners manual says i should use nonresistor and i already have 5k cap so should i be using nonresistor or what ? unless maybe i could find a non resistor cap somewhere. the cdi-coil is all one unit. electronic stuff isnt my specialty

Yes, i know of castor and moisture, but it has never been a problem for me.
With petrol and castor i only got like 'syrup/caramel' coating after a while.

Are the answer laying right in front of me?
Is Shell advance racing m containing anticorrosion additives?

Reading in Shell´s pdf document they say 4% mixture is recommended for motorcycles.

Can it also be, the more oil the more problems?

[oldjohnno]

Yes, i know of castor and moisture, but it has never been a problem for me.
With petrol and castor i only got like 'syrup/caramel' coating after a while.

Are the answer laying right in front of me?
Is Shell advance racing m containing anticorrosion additives?

Reading in Shell´s pdf document they say 4% mixture is recommended for motorcycles.

Can it also be, the more oil the more problems?

I use Shell M with methanol too and have never experienced any corrosion. But if I don't purge it I get a LOT of water collecting in the crankcase, especially in hot and humid weather. It may be less of a problem in a cold climate.

[oldjohnno]

Hypothetical question: if you had some sort of magic inlet valve that needed no space or drive mechanism, where would you put it? In other words if you had complete freedom in placing the intake port and passage, where would it be and in which direction would it be aimed?

[Lightbulb]

Years ago, one of the methanol suppliers used to add a small amount of acetone to their stock. It allowed it to blend with the oil a little better. In the model engines, adding a little bit of diethylether, or ether at about 1% also improved oil mix stability and also aided in the fuel mixture being consistent. ie a very stable needle valve setting. But storing for any time was a problem as the ether would easily diffuse out of the fuel.
Neil

[Frits Overmars]

Undoubtedly using exhaust gas to pressurise the tank has had a beneficial effect chemically.

It's common practice in methanol-burning F3D model aeroplanes, but with one important restriction: the fuel is contained in a rubber bladder inside the tank.
The exhaust pressure works on the outside of the bladder, so exhaust gas and fuel never come into direct contact. Just as well, because the H2O-content of exhaust gas is quite a bit higher than the H2O-content of ambient air.

happy birthday Frits, your present is under your bed.

Thanks Husa, but I'm not going to fall for that any more. For years I've been looking under my bed before I went to sleep, but there was never a pretty body there waiting for me.