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 Post subject: Re: H2 shift drum detent
PostPosted: Fri Sep 21, 2018 9:45 pm 
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Location: Rio Rancho, New Mexico
I played around with the shift arm and drum holder many years ago. I modified it into a 1 down 4 up. I will tell you there is a reason for the a semi light spring on the drum holder and the minimal depth. The shift shaft is so long there is minimal torque available to turn the drum. I ended up with a lot of modification just to get the shift lever to move the drum. This should be an interesting mod still. :thumbup:

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 Post subject: Re: H2 shift drum detent
PostPosted: Fri Sep 21, 2018 10:02 pm 

Joined: Thu Jun 09, 2011 11:25 am
Posts: 3156
Very interesting detent roller, nicely done. The Kawasaki dirt bikes and the H series racers use a two detent setup, one is like the stock one on the pins. The second is a roller that runs on the separator between the pin grooves, with a semi circular cut for the second detent for neutral.

Those sets use one spring between both levers, not dead ended to the case.


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 Post subject: Re: H2 shift drum detent
PostPosted: Sat Sep 22, 2018 11:32 am 
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Joined: Thu Sep 29, 2016 4:32 am
Posts: 615
Location: Indianapolis, IN
I'm hoping the increased detent force won't be so much of a problem with a roller tip to offset the shift effort. My memories of older Japanese gearboxes was that they were always on the edge of giving trouble, and an H2 with the kind of power they can make, and lack of new replacement parts, scares me. It might be that my box needs to be shimmed into gear better, but I thought I would start with the obvious external issues and go from there.

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 Post subject: Re: H2 shift drum detent
PostPosted: Sat Sep 22, 2018 1:55 pm 

Joined: Thu Jun 09, 2011 11:25 am
Posts: 3156
You are on the right track. How did you stop the drum from the original neutral detent when you went to 1 down, 4 up? I did mine by tapping the drum in the fork groove, and adding an allen bolt that was staked in place, and Lock-Tite bathed. The drum won't rotate into the original neutral position.

Then, I went to the dual levers for detents, and longer shoulder bolt. the levers make an X of it. And, as I said, I added a groove on the round portion of the drum between the slots the pins run through, in the position between 1st and 2nd, as the racer and earlier dirt bikes have.

I remember that with the H racers, with the engine running and the bike not rolling, it wasn't the easiest of tasks to find neutral, even on my Yamaha dry clutch racer engines. So, I developed an edge. With the clutch engaged in neutral, the pressure plate spun with the clutch. When the trans went into gear, the pressure plate stopped rotating with the clutch, as it was now connected to a transmission that wasn't spinning. It became part of the 'find neutral' operation to look down at the clutch spinning, and when the pressure plate started to spin with the clutch, the trans was in neutral I could let the clutch lever out without killing the engine. Only thing was, it looked a bit odd to be running the engine while completely bent over the fuel tank, looking at the side of the engine. Only a few others ever caught on.

Can't do that with a wet clutch, though...drat!


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 Post subject: Re: H2 shift drum detent
PostPosted: Sun Oct 14, 2018 4:49 pm 
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Joined: Thu Sep 29, 2016 4:32 am
Posts: 615
Location: Indianapolis, IN
Well it took me awhile, between just getting this thing to work out in my head, and in CAD, then figuring out how to fixture and machine it... tricky little bugger. The AN rivet retains the bearing, but it does not really need that, it can't come off. The arm is one piece of 4130, rivet does not hold the bearing boss on...Still have some fiddling to make it all work. Couldn't use the stock pivot bolt so had to make a cap screw one. The spring arm is longer and set for more preload from stock.


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1974 Kawasaki H2B 750, 1981 Yamaha XV750 Cafe, 1986 Kawasaki KDX200, 2003 Honda XR100, 2004 SDG140. 2006 Ninja 500R Turbo intercooled fuel injected.


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 Post subject: Re: H2 shift drum detent
PostPosted: Sun Oct 14, 2018 6:11 pm 
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Joined: Thu Sep 29, 2016 4:32 am
Posts: 615
Location: Indianapolis, IN
Crap that's a nice improvement! Shift just sitting feels snappy, shift drum snaps into position, yet no flexy shift shaft issues. Feels like a modern bike shift. Note the detent spring with some actual tension on it. Now just have to deal with the shift arm centering pin and it can go back together.


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 Post subject: Re: H2 shift drum detent
PostPosted: Sun Oct 14, 2018 7:17 pm 

Joined: Thu Jun 09, 2011 11:25 am
Posts: 3156
Nope, not done yet, you need the over and under shift claw. The racers had the claw that had both the pull teeth on the bottom of the grim, and claws that stopped the shaft and shifter from over shifting. Some of the other Kawasaki' two strokes used them, but they were different size. It might be the smaller triples. They help.

Remember, those shift detente were hardened steel,,keep a close look at the bolt pilot and hole in the lever you made.

The offset pin will do wonders getting the claw centered.


Last edited by H2RTuner on Mon Oct 15, 2018 10:58 am, edited 1 time in total.

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 Post subject: Re: H2 shift drum detent
PostPosted: Mon Oct 15, 2018 7:37 am 
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Joined: Thu Sep 29, 2016 4:32 am
Posts: 615
Location: Indianapolis, IN
I considered having this heat treated, but the only wear location is the pivot. I have almost tripled the thickness of it from stock, at the pivot, it's .190" thick there, and has MUCH better fit on the machined cap screw, which is heat treated. After thinking about it, the amount of movement there is minimal, rotates about 30 degrees per shift. So I don't consider that a wear factor at all. As long as it can't overshift, as it was doing before with the loose centering pin, it will be fine I think. Going to TIG weld the sides of the centering pin and tune the up and down shift movement by filing the sides of that. It needs more than an eccentric pin, the pin needs to be bigger than 8mm it looks like.

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1974 Kawasaki H2B 750, 1981 Yamaha XV750 Cafe, 1986 Kawasaki KDX200, 2003 Honda XR100, 2004 SDG140. 2006 Ninja 500R Turbo intercooled fuel injected.


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 Post subject: Re: H2 shift drum detent
PostPosted: Mon Oct 15, 2018 12:15 pm 

Joined: Thu Jun 09, 2011 11:25 am
Posts: 3156
the pivot i the highest loading area on the bolt and part, just keep a close look at it as you go.

The shift claw I am speaking of can be seen in the shifter mechanism page on bikebandit, for the 1974, 1975 S3/S3A, and 1976 KH400. It has a second claw that is a part of the lever above the drum, and stops the lever from over shifting the transmission. This is the same sort of device the H1R and H2R shifters use.

One important thing to know if you build one of those levers, there is a ledge in the upper case that catches oil flung off the primary bear, to divert onto the shafts inside the transmission, that is right behind the lever. This ledge is removed on the racer bikes, and isn't there in the S/KH series. It would need to be removed if the upper claw over shift part of the lever was added, not hard to do, I have done a few with the engine together, I just mask off EVERYTHING and cut away.

As far as the stop pin, the claw helps with that function as far as over shifting, with the offset doing what it is supposed to do, get the lower shift lever centered between the drum pins. In the standard lever shifter, the pin also acts as the stop for the lever, but may need some alterations to get the shifter stops configured correctly.

Take a look at the S/KH lever, it should be 'instant understanding' for you.


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 Post subject: Re: H2 shift drum detent
PostPosted: Mon Oct 15, 2018 1:08 pm 
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Joined: Tue Jun 07, 2011 6:37 am
Posts: 10460
Location: Rio Rancho, New Mexico
I don't see why you would have a overshift problem, that is very unusual. If it really is a bad problem for you, there is a super easy fix. Not my idea, but a great one, nonetheless. Just weld a small stop with a curved face onto the shift arm. When at full shift arm movement the stop is on the next pin up, stopping an overshift. :thumbup:

Image

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