Kawi2strokes.com Forum

An H2 in Japan, I think....

Vintage pictures rock!

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steve

The Japanese dry clutch photo shows the finned dipstick handle. That dissipates the heat from the clutch that's not cooled by oil.

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If it surges, that's normal, upshift.

Actually, dry clutches are far superior to wet clutches. The ONLY adverse issue with the ones for H1R and H2R, are the metal friction plates. If you hold one of our dry clutches out at a long traffic light, you will over heat the friction and steel plates, and warp them. If you have the parts for a dry clutch, and build one for the street, DON'T hold the clutch released for long periods of time.

Now, realize that Jawa, Bridgestone, a lot of European bikes, and even one series of the Suzuki Limited Production 1100 bikes all had dry clutches, with composite fiber plates, and they work just dandy. Kevin Cameron and myself have both built dry clutch setups using the stock street bike clutch covers, modified, stock later model inner clutch hub, end plate, springs, plates and modifying the outer clutch hub with a spacer to clear the seal ihn the clutch cover. LOTSA WORK, but, superior clutch.

The input shaft for the H racer dry clutches is 10.00mm (.394 inch, just at 4/10ths of an inch) longer than the street bike stuff, and if you are a good machinist, and can figure stuff out, doing this isn't a real problem. I am doing one on my decades long liquid cooled H2-(R) street bike engine, using an early distributor drive H1 street bike cover. Most of the stock street bike input shafts have a recess on their hub ends, and most people don't realize it is for a seal, for the push rod, to take the same seal that is in an H1R/H2R input shaft. My objective is to use the kick starter, stock oil pump, tach, and distributor drive to drive a Yamaha TZ250/350 early water pump.

In the outer hub, the gear was separated from the hub, a spacer was made to space the hub outward, bolted back together, and the spacer was also the outer seal race. To make up for the increased thickness of the outer hub, the inner hub flange back face of the shaft area was cut down 6.00mm (.240 inch). It is a juggling act, but, works if you do it right. To get the nut to sit in roughly the same place on the input shaft, the inner face of the nut boss on the inner hub was cut 2.50mm's, (.100 inch). An extra push rod ball was inserted to lengthen the push rod.

The only other mod of the stock wet clutch parts we did was to make a full width outer ring, for the outer hub, closed off the hub fingers so they wouldn't crack and break off from no support. Look at a factory dry clutch outer hub bell, and you will see what Kevin and I built, and added to the hub, the cover with the holes in it that spins with the clutch. This part is a special part on the H racers, is the outer hub that bolts onto the gear.

Some years ago, I did the same to an S series clutch, for a race project for a guy in Oregon, never did hear if he ever got it, nor the whole bike done, or raced it.

This is an involved project, and if you have the time, machinery, can weld both aluminum and steels, and patience, would make for a great time waster if you get bored with things in general. The icing to the cake would be a 6 speed as well. I haven't found an existing street bike trans that will interchange easily...yet, but, I'm always on the lookout for one.

If you were doing a H1 dry clutch, it would be good to use H2 primary ratios to unload the box. Tuner is right on this one, am sure Dave C will concur. From memory I told him how to reverse the PD gear etc and make a dry clutch for one of his H2's.

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I am just a man working in a tin shed.

Thanks for the replies. I am not sure if I am going to do this project or not, but now hearing that it is possible with not obtaining rare h1r parts I am going to look into it. The thing that really got me thinking I will probably get involved in this project was this statment from tuner, as it sounds like any other project I get I get my hands on.

I know that Nev Lush knows "The Other Nev", Neville Doyle. Doyle was our Australian counter part at Team Kawasaki, and I know he did a couple of street bike dry clutches way back when, using the street bike parts and input shafts, as Kevin and I outlined the process to him a couple of times when he and his team were here in the mid-1970's.

The keys to getting a dry clutch to live on our engines for the street are to use the wet clutch friction and steel plates, the frictions are fiber, not steel, and work either way, wet or dry. Yamaha uses the same friction coating on their TZ plates as they do with their wet street bike clutches, and those dry clutches work excellent. And, don't hold them released for long periods of time. If you get caught at a long traffic light, take the transmission out of gear and let the clutch out.

No matter how much power/torque I made in the TZ twin and four cylinder engines over the years, I never replaced a clutch friction, or steel plate, nor a spring, they just kept on truckin'. Hurley used to use a street bike friction plate in his TZ750, I think from an XS1100 or so, only differences were the street bike plate was a hair thinner, so he ran and extra friction plate back to back, and the street bike plates cost a lot less than the dedicated TZ part.

Thanks for your insite tuner, if this project ever comes to be, I may have to pick your brain a little more on the subject.

I personally don't see anything "far superior" to a dry clutch. Ducati has finally gone to a wet clutch (on some models) so they don't sound like a wheat thrasher. Dry clutches were originally for quick change capability as racing clutches were totally abused in starts and it made it easy to change plates. Racing clutches don't have to deal with muddy rain water and other crap that is on public roads, as most race track are swept pretty much clean.

And just the fact a dry clutch will over heat if left in the released position, shows a superiority with wet clutches as the oil is actually cooling them. A properly adjusted wet clutch works fine.

Now, if you are looking for something to just be "different", then a dry clutch is great...........

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

Sometimes things are more about the build for me, to see if what I think I can accomplish in my head can actually come to life in the real world and do it within the parameters that I set. You should understand this John, the fiberglass tank that you run on your bike is not far superior to a stock steel tank. Some will say that the time and effort spent on it was not worth it. In the end though it was something "different".