ulmer clutch kit question

[Srxspec]

You're simply not losing 1 hp per 100 rpm past the peak. That can be true with with unforgiving 2-stroke motors, but the 4-stroke is very forgiving and has a wide powerband.

10,500 RPM = 80.0 hp
11,200 RPM = 81.2 hp ***Peak HP***
11,700 RPM = 80.0 hp

So in 1200 rpm you only changed 1.2 hp from the lowest to the peak HP. As RPM increases so does your MPH because engine speed (actually clutch speed) dictates the MPH you can run with the given chaincase gear ratio.

 

[Reaper]

Must make tuning 4-stroke much easier I would think ?

 

[BV1]

You're simply not losing 1 hp per 100 rpm past the peak. That can be true with with unforgiving 2-stroke motors, but the 4-stroke is very forgiving and has a wide powerband.

10,500 RPM = 80.0 hp
11,200 RPM = 81.2 hp ***Peak HP***
11,700 RPM = 80.0 hp

So in 1200 rpm you only changed 1.2 hp from the lowest to the peak HP. As RPM increases so does your MPH because engine speed (actually clutch speed) dictates the MPH you can run with the given chaincase gear ratio.

I know I know... I was just saying 1 hp per 100 rpm to expand on my example. You kinda ignored my other questions though, this is a learning experience for me. I spent last night googling clutching and the way I understand it... (correct me if Im wrong, Im not trying to argue just to learn)

What you said is:

As RPM increases so does your MPH because engine speed (actually clutch speed) dictates the MPH you can run with the given chaincase gear ratio.

But the way I understand it RPM should increase due to the excessive MPH (because the clutch is fully shifted out and can no longer compensate for the MPH and the Chaincase gearing to keep down the RPM) not the other way around.

To me HP is power and every single 1.2 HP counts, the more power, the more accelleration. If I wanted to take advantage of that 1.2 HP I dont see how it would detriment my top end my revving lower, as eventually my clutch would shift out and I would see higher then 11,100 RPM anyways right?

Let compare two sleds on paper with the same Primary and Secondary clutches, everything the same, except for weights to allow shifting at a different RPMs.

Sled A is Shifting at 11,100 RPM WOT
Sled B is Shifting at 11,700 RPM WOT

Lets say they race on pavement for a mile, at the track, or your favorite ice lake or w/e.

Assuming they hook up the same as the MPH increases:

A - 5 MPH - 11,100 RPM - 81.2 HP - Not fully shifted out
B - 5 MPH - 11,700 RPM - 80.0 HP - Not fully shifted out

A - 60 MPH - 11,100 RPM - 81.2 HP - Not fully shifted out
B - 60 MPH - 11,700 RPM - 80.0 HP - Not fully shifted out

From 0-60 Sled A has produced an extra 1.2 HP consistently and should be in the lead slightly.

A - 85 MPH - 11,100 RPM - 81.2 HP - Fully shifted out
B - 85 MPH - 11,700 RPM - 80.0 HP - Not fully shifted out

At 85 MPH Sled A's clutch is now fully shifted out, and the clutch can no longer maintain 11,100 RPM for much longer. Its not like the clutch won't allow the engine to exceed 11,100 RPM, or 85 MPH, right?. I think that Sled A will still accellerate but now that RPM will start to increase with MPH instead of staying at 11,100 RPM. However it has had a 1.2 HP advantage until this point.

A - 95 MPH - 11,700 RPM - 80.0 HP - Fully shifted out
B - 95 MPH - 11,700 RPM - 80.0 HP - Fully shitfed out

A - 98 MPH - 12,000 RPM - 79.0 HP - Fully shifted out
B - 98 MPH - 12,000 RPM - 79.0 HP - Fully shitfed out

At 95-98 MPH both sleds are fully shifted out and pulling the same RPM, but I think that Sled A will have reached 95 MPH first as it produced more HP on average through the run.

The exact numbers and RPM's may vary I didnt calculate gear ratios for this but you get what Im trying to say.

If the above is inaccurrate please let me know.

I built my 95 Eagle Talon TSI from the ground up and I would have never been able to take advantage of every last of those 386 HP without the help from guys from www.dsmtalk.com their collective input and advice. I feel the same about my sled and this website. I eventually want to turbo it and turn it into a monster, but for now, I want to understand every detail about the sled and how the clutching works before I get into Cam shafts, tuned intake/exhausts and fuel accellerators... because each of these modifications will require a change in clutching.

Thank for your patience,

-Steve

 

[mlloyd]

SRXSPEC - I am considering using your clutch kit, increasing gearing to a 20 tooth and installing a Excell exhaust. Have you done any testing on this combination. I am hoping the clutch kit can maintain some of the bottom end pull while benefiting in some increased top end. I am currently running the stock gears in the FX model. Any information would be greatly appreciated.

 

[Srxspec]

BV1, buy the clutch tuning hand book by Olav Aaen. I believe you can find it on http://www.amazon.com. Then start testing different setups and taking alot of notes.

mlloyd, the 20 tooth will work fine. In some snow conditions it is actually better because it spins less down low under acceleration.

 

[Otter]

I tried putting a secondary clutch off my old 600vmax opn the phazer and i couldnt get te prober offset. i would have to either move the motor over or machine down the ineer shaft on the secondaty.

otter

 

[Srxspec]

Which year 600 was it off of? If it was a 95 or 96 model 600 it should've slide right on with no problems. You may have to adjust the washers that are on the jackshaft to get the proper offset. If it didn't slide all the way onto the shaft it was the wrong year secondary.

 

[Otter]

It was off a 96 vmax 600. I had all the washers on the shaft removed and i would of needed at least another .125 to get it close. The clutch inner shaft was up against the jackshaft bearing. The splines match up perfect. This was on a 09 rtx so maybe things have been changed a bit on the newer machines.

otter