Bully J/S Clutch engagement...

[Ted Hamilton]

I saw a Bully J/S clutch being advertised at BMI as engaging at 10,200 RPM....is that correct? It was a 3 disc... If I could get one that engaged at 9000, I'd use it. I assume that I could just add bolts and nuts to the lever arms on this one? Being used for a 3/4" shaft KT-100....each disc handles 10hp? I'm tempted to try a 2 disc but don't want to burn it up...

 

[ECkarter]

2 disk will be fine

 

[alvin l nunley]

The KT100 reaches peak torque very close to that RPM. You are reading the engine RPM right?

Divide that by the ratio from the engine to the Jack shaft primary. It will tell you how fast the clutch is spinning. Multiply the engine torque by the primary ratio to see how much torque the clutch is absorbing. I see no reason for running a 2 disc clutch. My preference would be 3 or 4 disc. That clutch is absorbing a lot of torque. Depending on the primary ratio, anywhere from 2 to 3 times the torque an engine clutch would be absorbing.

 

[Ted Hamilton]

I'm not running a jackshaft, Al.
It's an old-style KT-100 with the 17mm straight shaft (inboard) that someone professionally machined a sleeve to convert to a true 3/4" shaft. I'll be using the clutch in the "normal" sense. If I could get a 2 disc clutch, and engage it at around 8000, I'd be happy.

 

[medusa51]

Ted, I run my jackshaft at about 6600 rpm. I tried it at 10300 rpm and it did not work for me on a dry dusty track. It was like popping the clutch on a motorcycle and all it did was spin the tires so I set the springs to the lowest engagement. works great now. The spring height is at .300 on a 3 disk el diablo.

 

[Chris Cooper]

I'm not running a jackshaft, Al.
It's an old-style KT-100 with the 17mm straight shaft (inboard) that someone professionally machined a sleeve to convert to a true 3/4" shaft. I'll be using the clutch in the "normal" sense. If I could get a 2 disc clutch, and engage it at around 8000, I'd be happy.

Morning Ted,

Are you planning to run the clutch directly on the crank shaft ? If so, I would check with Buller (or the guys at Viper) to see if they offer a spring and weight package for that high of an engagement. The most I’ve seen (and I have not looked too much) is a 4200 ish engagement speed.

Just a thought.

 

[alvin l nunley]

And and and and and and
You said a "Jack shaft clutch" so I assumed you're running a Jack shaft. You must be running a KT100 with a 3 hole can muffler? Only then would I ever set the clutch that low.

Maybe with a little more detail you could get better advice.

 

[twostroketoowoke]

You’ll have a hard time making a bully style clutch engagement that high at actual engine RPM’s on the crank, and it will generate a lot of heat. The engagement ratings posted about that clutch (10.2K) are at actual engine RPM in conjunction with a jackshaft using a 2.71 primary which makes the actual clutch engagement 3,763.

 

[twostroketoowoke]

If not using a jackshaft is a must, your safest bet is sadly a low stall JICA/KT Dry clutch or an old style wet bathe L&T/Steel Nytro

 

[ECkarter]

If not using a jackshaft is a must, your safest bet is sadly a low stall JICA/KT Dry clutch or an old style wet bathe L&T/Steel Nytro

Was just going to point this out as well, Misread that it wasn’t going on the jackshaft. I would put a belt driver on the crankshaft and jackshaft it, or swap the crank half out and use a jica /kt clutch as pointed out.

 

[Ted Hamilton]

The engagement ratings posted about that clutch (10.2K) are at actual engine RPM in conjunction with a jackshaft using a 2.71 primary which makes the actual clutch engagement 3,763.

That's what I needed to know....thanks!

 

[Ted Hamilton]

Sounds like a jackshaft is in order. I already have a 3/4" bore 8mm driver. Everything will go on one side, so I'll have to watch the bearings...

 

[Hoppy]

HDC-5 from Horstman. Small 3 disc dry clutch specifically for the KT-100.

 

[MO Predator Racer]

I dont know anything about 2 strokes or 2 stroke racing, but what is the highest rpm you record during a race?

 

[spincycle]

I dont know anything about 2 strokes or 2 stroke racing, but what is the highest rpm you record during a race?

I try to get my 2 cycle 125 Sudam to approx 14,000 engine rpms...

 

[medusa51]

I turn my 125cc leopard to 14900rpm pulls the whole time. Hold my beer!

 

[alvin l nunley]

2 disk will be fine

I dont know anything about 2 strokes or 2 stroke racing, but what is the highest rpm you record during a race?

KT100, Horstman 3 disc engine clutch, with a pipe, 15,200. Direct drive, 17,000. Average Sprint track.

 

[ECkarter]

KT100, Horstman 3 disc engine clutch, with a pipe, 15,200. Direct drive, 17,000. Average Sprint track.

Al, you need to get out and go dirt racing.

 

[Ted Hamilton]

14.5-15K is what I was seeing for top RPM on dirt KT-100.... With not much drop in the corners. Patriort Speedway, Blacksburg, SC.

 

[alvin l nunley]

Al, you need to get out and go dirt racing.

I would love nothing better, I miss those weekends at the track. I'm probably losing contact where the KT100 comes in. Maybe they don't turn the RPM they use to, but that's the RPM they turned when I raced on a weekly basis. I remember when I first purchased a KT100. One of the first 100 imported into the US. Three-quarter straight shaft, stock, out-of-the-box, no cc check. I have to assume it was the 12.5 CC head. My first race was at Kerman California, it turn 14,500 down the straight. Maybe I should get out to the track and see what their turning now. It's been over 40 years since that first day at Kerman, who knows how many changes have been made since then, they may not be able to turn the RPM they use to. It could happen!