Stage 6 90cc Build

[wrhracing]

Well guys I have completed my first Stage 6 90cc build. It was quite impressive after tuning it in. I had to build a head for it of course, bore and replate the cylinder, stroke the crank, etc. The good news is it can use either the 12 or 13 pin malossi piston with out uncovering the exhaust port at TDC.
35mm D slide really makes it run strong.
I will say the crankshaft selection makes a world of difference in performance.
Anybody else out there building any new hybrid engines?
I sure would like to see a Rotary valve DRX running around the Nationals next year. It would open up another game of catch up.

[Team-Ty]

I'm trying to get a variable exhaust valve to work off a rotax motor and the rotary valve would be great, have thought of that already but the drive of the valve is making me step back. I just have to finish buying this house and then its on. Im out of the 50s next year and the 70 motor will have to be built. Tommy Alley said that we need to talk some time

[wrhracing]

If Tommy Said it then it's got to be true.
251 680 4972 after 6pm.central. Billy Holt.

Use the power valve that is exhaust pressure regulated....simpler and no tricky mechanisms to foul up. The power hit is adjustable by spring strength.
I have had discussion about the a power valve CR 85/105 Cylinder assy. recently. It seems interest is rebrewing about the state of tune of the shifter classes.
Ever heard of electronic boost bottles?

[fomospede]

Originally posted by wrhracing
Well guys I have completed my first Stage 6 90cc build. It was quite impressive after tuning it in. I had to build a head for it of course, bore and replate the cylinder, stroke the crank, etc. The good news is it can use either the 12 or 13 pin malossi piston with out uncovering the exhaust port at TDC.
35mm D slide really makes it run strong.
I will say the crankshaft selection makes a world of difference in performance.
Anybody else out there building any new hybrid engines?
I sure would like to see a Rotary valve DRX running around the Nationals next year. It would open up another game of catch up.
all talk
no specs or pictures?

[wrhracing]

I didn't take pictures, but what specs do you need? You know what the cylinder looks like... You know what a stroked crank looks like,a 35mm D-slide is a 35mm D-Slide. etc. etc.

[fomospede]

specs
bore
stroke
which s6 cylinder
buy saying you built the head you took a piece of billet and spun it up in a lathe and or with some mill work?
let us at your genius ;)

[wrhracing]

45 x 50 S6RT . Spun it up out of aluminum. 180psig. 9mm squish band. 8.5 degree.

[#404's Dad]

I'm sure it runs like a scalded dog!!!

[john willhoite]

how does it compare to a 2fast?

[fomospede]

what pipe
what intake
carb facing rear?
obviously you tuned it the right way on a dyno
what kind of power at what rpm?

[FISH ON!]

I'm less interested in the specs and more interested in seeing it run the Nationals against all the others................. right now it looks like there is one builder who pretty much has dominated the 90cc CVT class this year at the MX Nats.

[wrhracing]

Originally posted by john willhoite
how does it compare to a 2fast?


My very fastest 2 fast which was prior to this s 6 build had more amazing torque then I had ever felt before on any other 2 fast.
The stage 6 90cc build also has the same impressive torque. And there is more to be gotten out of it since this is just the initial build. So further refinement is available.

[wrhracing]

Originally posted by FISH ON!
I'm less interested in the specs and more interested in seeing it run the Nationals against all the others................. right now it looks like there is one builder who pretty much has dominated the 90cc CVT class this year at the MX Nats.

Your absolutley right one builder this year . The year before that ,The year before that, and it goes on. But who was it that built the very first 2 Fast 90 before they were even 90cc. Mike Harper's and Neil Dupont's son's had the only two built anywhere. And they were extremly fast compared to anything else available.
So if it sorts out that it runs at Loretta's then it runs at Loretta's... or before!

[wrhracing]

Originally posted by fomospede
what pipe
what intake
carb facing rear?
obviously you tuned it the right way on a dyno
what kind of power at what rpm?

Can't tell you which pipe will be on it when it runs and even if I did it would not be available publically. Intake is one of my own intakes with the reeds rotated 90 degrees and stuck in the cases a bit. And no I didn't tune it, in your opinion, the right way with a DYNO. but I did use a calculater quite often.
The most a dyno has done for me is to be a lie detector,prove my jetting, and give horse power numbers comparable to other peoples dyno's. I let my engines freely be tested on a dyno of the customers choice independently. If they tell me the result then great.
I'm generally not real big fan of ultra high RPM'S and I do stay just under the ratings for the crankshaft. Long term engine life and rideability (Torque) is what I generally enjoy building the most.

[mmsoup]

Billy

I don't want to challenge you to share anything in particular, I have seen your motors in various quads and they were stout. I am more interested as to why you would take a Stage 6 cylinder and bore it (I'm assuming that you port mapped it and adjusted timings etc) and then turn up a new head instead of just tuning a 2Fast?

Sort of like certain folks playing around with the Polini BB and the crank, I didn't get it unless they were just trying to create a market and sell something.

Why not take a TCR cylinder and make something out of that kit? Or better yet an Airsal 88cc kit and put some wrh majic in that?

I guess I am wondering why? I don't pretend to have the skill set you have but I am wondering what the motivation is

[wrhracing]

Originally posted by mmsoup
Billy

Why not take a TCR cylinder and make something out of that kit? Or better yet an Airsal 88cc kit and put some wrh majic in that?

I guess I am wondering why? I don't pretend to have the skill set you have but I am wondering what the motivation is

That was the request I received, to take the Stage 6 kit, build it and see what can be made from it.

I had done a couple of the TCR kits 2 seasons ago when there were no 2 fast readily available. One of the kits actually was from a Piaggio which was really a pain considering the cylinder stud spacing was a different pattern then the minarelli and the coolant comes in from a different place.

I have a Airsal crank/cyl kit under the bench, the short rod, small top brng., and small crank diameters would kind of add more work to it, but I think that may be a very good starting point for a next "Fun" project. The next engine will probably be a shrouded crankshaft design to keep the crank turbulance (wind) out of the equation.
I always wanted to complete that style engine, as Harpers engine from 2-3 seasons ago had a half shroud around the crankshaft and performed supurbly all season.

[wrhracing]

Originally posted by mmsoup
Billy

I am more interested as to why you would take a Stage 6 cylinder and bore it (I'm assuming that you port mapped it and adjusted timings etc) and then turn up a new head instead of just tuning a 2Fast
Port mapped, degreed, time area. Had to machine the cases to allow the cylinder to sit further down just to bring the transfer port timings in to a usable range, this also allowed me to use a shorter skirt 12 pin malossi piston (less weight) in the cylinder without uncovering the exhaust port at tdc. Otherwise the heavier 13 pin kit would have to be used.
then the exhaust,and exhaust port had to be adjusted for the larger displacement of the engine which included machining a new exhaust spigot for the exhaust flange.
I did it because if you don't try to outrun what is currently the fastest out there, then the class kind of stagnates and becomes complacent with what is available. Much like the 70cc class had become in the day of the Metrakit and 20mm Pe carb setup of a couple years ago. I tried to tell them on this forum of what the real engines ran like and they shunned me. Well ,OKAY..... so they had to step the game up the next year big time. They were caught with there pants down.
I just try to think outside of the box, find out where the restriction is in getting to the next level and un-restrict.

[wrhracing]

Originally posted by mmsoup
Billy


Sort of like certain folks playing around with the Polini BB and the crank, I didn't get it unless they were just trying to create a market and sell something.


I don't know who your referring to but, I can guess by destroking it, it becomes a legal 90cc.
After looking at the pictures of the kit, and I haven't had one in my hands.... i would probably long rod it and then get a piston with the pin closer to the dome of the piston itself, possibbly even deboring/resleeve then nikosil it. To come up with the very base of the engine design.
Unless of course it was to be used in only wide open, flat track style tracks. The approach would then alter a bit.
Your rider still has to be able to hang on to it and the on going mechanicals have to be maintained.
I have seen the "create the market " happen often and others have wanted the next gimmick to sell. Us old schoolers refer to it as "Drinkin the Kool-aide".

[mmsoup]

Thanks Billy

I appreciate the insight, like I said originally, I have seen how good your motors can be and hope you can make something out of the Stage 6 build. I didn't ask one question correctly, so here goes, Can you make any kit perform at the absolute level depending on requirement (MX, XC or TT) regardless of kit manufacture, if you put the necessary time into the math?

[Logan #34's Dad]

Originally posted by wrhracing
The next engine will probably be a shrouded crankshaft design to keep the crank turbulance (wind) out of the equation.
I always wanted to complete that style engine, as Harpers engine from 2-3 seasons ago had a half shroud around the crankshaft and performed supurbly all season.

Hey billy, in reference to the shrouded crank idea, On one of the scooter forums from across the pond (i believe i've seen you post on a couple) there is a guy that has detailed photos of how he did it for his racing engine. Inserted a ring on each half of the cases only leaving a gap where the crank rod needs to travel. interesting stuff........ I dont know how it'd affect power but.......

[wrhracing]

Originally posted by mmsoup
Thanks Billy

I appreciate the insight, like I said originally, I have seen how good your motors can be and hope you can make something out of the Stage 6 build. I didn't ask one question correctly, so here goes, Can you make any kit perform at the absolute level depending on requirement (MX, XC or TT) regardless of kit manufacture, if you put the necessary time into the math?
I'll say there would be certain kits I would target for x-country over others, and the obvious High RPM kits for flat track, of course there are dominate kits out there now. I'll get back to you in a bit. Gotta get to work.

[#404's Dad]

Originally posted by mmsoup
Thanks Billy
Can you make any kit perform at the absolute level depending on requirement (MX, XC or TT) regardless of kit manufacture, if you put the necessary time into the math?

In my experience a motor built for either can be made to perform at any, we have TT motors that are capable of being up front in MX and vice versa, its all in the clutching and gearing in my opinion.

[wrhracing]

Originally posted by mmsoup
Thanks Billy

I appreciate the insight, like I said originally, I have seen how good your motors can be and hope you can make something out of the Stage 6 build. I didn't ask one question correctly, so here goes, Can you make any kit perform at the absolute level depending on requirement (MX, XC or TT) regardless of kit manufacture, if you put the necessary time into the math?

All kits are not created equal...
Example: The cast iron kits (H2O 52mm Bore).(90cc).(APX/DRX)
Stock the transfer tunnels are not "T-Cup Handle" shaped and the available volume is lacking. The T-Cup shape promotes torque, lets the gases adhere to the dome of the piston better, and increases the available volume for the next charge with out as much disruption/direction change of the incoming gases. "Flows better".
Of course the exhaust ports, can potentially be better bridged if they could be sufficently cooled to prevent "Bridge Bulging" and the exhaust seizure that follows shortly after.
I have had the opportunity to build a bridged exhaust APX cylinder, I cut it with the intent of Higher rpms and maximum Horsepower. It is definatley an advantage over the oval port design especially while retaining reliability, offering ring support unmatched by the oval design. It ran real, real good.

[wrhracing]

Originally posted by mmsoup
Thanks Billy

I appreciate the insight, like I said originally, I have seen how good your motors can be and hope you can make something out of the Stage 6 build. I didn't ask one question correctly, so here goes, Can you make any kit perform at the absolute level depending on requirement (MX, XC or TT) regardless of kit manufacture, if you put the necessary time into the math?
Usually I can pull the most out of an engine if the math is done and you know what the "Math" does.
Example is Eric Havert: Heavy 70cc rider of a few years ago. How do I make a "70" win with a 60 to 70 pound handicap?
I had to go outside what others were doing and put huge reeds in, bigger carb, more compression, longer rod, and make it a pure ***** grunt motor with a pipe, that at the time, was state of the art in M.Q.racing.
In short sometimes the math says the cylinder manufacture didn't leave enough meat to put ports where you want them or cylinder sleeves are to thin, or you cut thru to Daylight trying to get a particular angle, or you epoxy ports up and reangle, etc.
Crankshaft weights are important as are case volumes, and rod length. All have there fit in the design of your engine. Occasionally a accident will lead you to something you had never thought possible.

[wrhracing]

Originally posted by #404's Dad
In my experience a motor built for either can be made to perform at any, we have TT motors that are capable of being up front in MX and vice versa, its all in the clutching and gearing in my opinion.
Thats a dominating style engine that occassionally becomes available to the capable MOM,DAD, & RIDER. I can recall a 50 engine that doubled the torque of others on a dyno.
I have one 50cc engine in the Nationals this year.....and it's held up well.
I'll stop at that. These kids really make me proud! I only wish I could be there to watch them ride.

[mini racer #39]

thanks dad for the great years Erik says WE were the fastest at 1 or 2 times and you sure did over come #39

[wrhracing]

Originally posted by Logan #34's Dad
Hey billy, in reference to the shrouded crank idea, On one of the scooter forums from across the pond (i believe i've seen you post on a couple) there is a guy that has detailed photos of how he did it for his racing engine. Inserted a ring on each half of the cases only leaving a gap where the crank rod needs to travel. interesting stuff........ I dont know how it'd affect power but.......

The Smaller YZ-85's have a partial shroud over their crank halves. I've seen other examples in the Road race end of the world, V-4 two stroke RG Suzuki's for example. Mostly I'm interested in just doing it to see if the effect on the power is worth the trouble.
I saw the ring insert, but an epoxy may be my method, or I could use 90 cases and a 50cc diameter crank.
I don't know right now but i do know it's gotta be 115* F outside. I'm hot and can't think right now.

[skyeryder]

Billy sent ya a pm