ESE's works engine tuner

[TZ350]

I think you are very high already, or just at max.

I just raised one up 5mm from bdc.

Tdc211 its encouraging to hear you have got good results with your 5mm dam, and Romeu its hard to measure mine with the cylinder off but it looks like the dam is about 6mm or so above the piston and still 5mm or so below the top of the transfers.

Well at least its good to know I am on the right track but I sure would like to know if this is the limit or if I can take it closer to the top of the transfers.

Then I remembered that Jan and Frits had talked about experiments where raising the exhaust port floor made more power by reducing short circuiting.

And by reducing the exhaust duct volume and to help guide the washed-through mixture back over the piston edge into the cylinder.

To make the raised floor work as part of an overall plan that was seen all the way thru by Jan at Aprilia, the area reduction at the port should be extended all the way to the flange.

Making this oval, and reducing the duct volume all the way to the exit then works with the 75% area guideline for T or tripple port duct exit geometry.

Lengthen it up to the flange face and make a smooth transition, like Wobbly advised.

Now I understand what Wob meant and why, thanks Frits.

[richban]

http://imageshack.us/scaled/landing/81/48301117th7.jpg

http://imageshack.us/scaled/landing/135/47867690ji4.jpg

http://imageshack.us/scaled/landing/81/21667591zu0.jpg

http://imageshack.us/scaled/landing/86/99514991ws5.jpg

Ahhhhhhhh ha.

[husaberg]

Ahhhhhhhh ha.

Ahhhhhhhhh.......sole? Grasshopper
do you speakey the lingo?
I guess Sir Stephen does,(Brian Demargerine) if you need it translated,where is the Japanese corespondent?
I will post some stuff in a minute. re the 54mm stroke RG250 crank going in the RGV250 courtesy of Vincent Crabtree. (VinCBR900)
With a bit of luck he might fill in the gaps as well.
Did i mention how close the stud spacing on the RGV are to my RSV copy molds?
He mentioned the center bearing needed to be changed. but from memory the spines rotor taper etc were all the same.

Hi,
I can try and dig it out of my archives - what you up to?

Basically, the best option for 54mm crank is to modify an RG250 from the mid 1980s. This is almost a direct fit, but the crank centre need modifying from 2 main bearings to 1 so machining down with a nice wide roller bearing from a TZ350.

If you want to run the TS200 cylinders, first of all find some which is difficult,so it is easier to get ZRT600 cylinders/heads from a Canadian/US snowmobile, and have steel powervalves that don't fall in and lunch the motor. You may have to do some crankcase boring. Then use Yamaha 66mm blaster pistons on TZ350 rods and a spacer plate to set the port timing for 180 degrees exhaust open, skimming the cylinder deck for the correct compression. This should get you something which runs but is not optimised - ports, ignition, powervalve control, carburetor etc. Then develop from there...

http://www.rgv250.co.uk/forums/index...ankases/page-2

[richban]

Ahhhhhhhhh.......sole? Grasshopper
do you speakey the lingo?
I guess Sir Stephen does,(Brian Demargerine) if you need it translated,where is the Japanese corespondent?
I will post some stuff in a minute. courtesy of Vincent Crabtree. (VinCBR900)

Looks like that was all a long time ago. There is loads of stuff on the RGV UK site. So much to sift through. Some say raise the barrels, another's says go piston flush and machine squish into the head. I will go with whatever makes the most toque. If going with a machined head squish. Is there a rule on the radius from the squish edge to cylinder. Or sharp edge transition. My head is spinning.

[wobbly]

There is only one rule grasshopper,NO radius from the squish into the bowl.
The other rule is to pull the squish down to the mechanical limit - ie probably around 0.7mm on an RGV then adjust the width to get around 38M/Sec MSV, usually 45 to 50%.
This generates good response and " torque" as you put it - but for sure will need a digital to retard the top end advance to get the overev back.

[richban]

There is only one rule grasshopper,NO radius from the squish into the bowl.
The other rule is to pull the squish down to the mechanical limit - ie probably around 0.7mm on an RGV then adjust the width to get around 38M/Sec MSV, usually 45 to 50%.
This generates good response and " torque" as you put it - but for sure will need a digital to retard the top end advance to get the overev back.

Yes 'torque' thats the stuff.

Thanks for that. I am getting my head around this all. The plan is forming. Cheers again.

[2T Institute]

Yes I think after reading a lot in the last few days an ignitech is in order no matter what.

The old 'kit' setup? Do you mean the 1.4mm base gasket and some compression. Seams lots of people talk about that being a good idea. And the 22d10 box?

Yep that's the old kit set up, it's been surpassed now mainly due to it pushing peak power up to 12,200 or so and allowing it to rev to 13,000. You can join the dots what happens after a hour of that.

If I was going to fit aprilia rsw cylinders I would fuck around with a old RG crank. How is Vince these days? Tell him I've picked up his torch about using inline kart engines

[richban]

Yep that's the old kit set up, it's been surpassed now mainly due to it pushing peak power up to 12,200 or so and allowing it to rev to 13,000. You can join the dots what happens after a hour of that.

Good to know. Well i will not be going down the route for sure. Cheers.

[husaberg]

Yep that's the old kit set up, it's been surpassed now mainly due to it pushing peak power up to 12,200 or so and allowing it to rev to 13,000. You can join the dots what happens after a hour of that.

If I was going to fit aprilia rsw cylinders I would fuck around with a old RG crank. How is Vince these days? Tell him I've picked up his torch about using inline kart engines

Tell him yourself i sent him a link..........
My take on using the RG crank is yes, it is likely not as good as a custom one,Of course is dearer than staying stock, But if you were going to tune up an old RGV for decent HP It would be silly not to rebuild the crank.
So seeing as the crank is getting rebuilt anyway you might as well rebuild the one with more stroke and thrown in some longer rods at the same time.

Don't you have something to do with a new crank for the RGV anyway Lozza?

[TZ350]

Bucket Racing Video from Chrisc's thread

Pictures of the bikes http://www.kiwibiker.co.nz/forums/sh...-warning/page7

[2T Institute]

Tell him yourself i sent him a link..........
My take on using the RG crank is yes, it is likely not as good as a custom one,Of course is dearer than staying stock, But if you were going to tune up an old RGV for decent HP It would be silly not to rebuild the crank.
So seeing as the crank is getting rebuilt anyway you might as well rebuild the one with more stroke and thrown in some longer rods at the same time.

Don't you have something to do with a new crank for the RGV anyway Lozza?

Having the crank pins indexed at 0-0 deg is as important as having it run true. I didn't do that much just found the bits , Gravmax88 was the smart one that rebuilt the crank and made it all work with big end thrusts.

[tdc211]

Raised floor 1st pull. I had power valve in the normal position .
Usually with the valve in this position the curve is straight.

This engine is smaller than my other posts at 103cc. I was able to hit 30hp at 12200 and a straight curve with some tuning.

[bucketracer]

I have been following this thread.



Here is my output shaft steel wheel dyno chart of my mx piped engine, a few ccs over 100.

Raised floor 1st pull. I had power valve in the normal position .
Usually with the valve in this position the curve is straight.

This engine is smaller than my other posts at 103cc. I was able to hit 30hp at 12200 and a straight curve with some tuning.

Interesting graphs, any chance of an overlay comparison of the original and the 30hp one with the raised exhaust port floor (easier to see whats going on), pictures?

[Yow Ling]

Raised floor 1st pull. I had power valve in the normal position .
Usually with the valve in this position the curve is straight.

This engine is smaller than my other posts at 103cc. I was able to hit 30hp at 12200 and a straight curve with some tuning.

What is the "normal" position ? How much did you raise the floor?

[tdc211]

Interesting graphs, any chance of an overlay comparison of the original and the 30hp one with the raised exhaust port floor (easier to see whats going on), pictures?

There is no original graph with a normal floor on this exact engine. This was a junk cylinder that needed plating so I filled up the floor and this bottomend has less stroke. I have done enough of these to know it is a straight line curve with a normal floor. After adjusting the valve to open faster the curve straightened out, no more dip.
It wanted more blowdown in the midrange. But remember the valve was set up for a normal floor on this pull. Really not suprising.
The floor raised 5mm did not hurt peak power. I am sure of that. I think it may have helped. But dyno box broke [new one is here] So we will see.