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TOPIC: What he said...measuring fork tubes

What he said...measuring fork tubes 11 Sep 2019 12:34 #810715

  • 577nitro
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So I decided to start measuring everything to see just how off the tubes could be on my other bikes. The stock 38mm fork tubes were, as Dr. G said .0035 off, at the axel it could three times that. The more modern suspension were far better, my 2008 VFR was only .001 off .

577nitro

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What he said...measuring fork tubes 11 Sep 2019 13:51 #810716

  • SWest
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How did you measure?
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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What he said...measuring fork tubes 11 Sep 2019 13:52 #810717

  • Dr. Gamma
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Wait to you measure the clearance between the frame boss and the swing arm bolt!!!!!!! Then the clearance between the inner swing arm sleeve and the swing arm bolt!!!! One of the very first things I noticed on '79 factory Kawasaki Superbikes was a very non-stock looking swing arm bolt and nut. When I put the swing arm bolt through my Kz1000 frame I quickly saw why they used something besides stock parts. There was like .035 thousands or more of play between the two. Same with the inner sleeve too!!!!!

I then had my favorite machine shop make me up a few oversize swing arm bolts. They also made me a tool that kept both sides of the frame in alignment as I hand reamed the frame bosses to size of the new oversize swing arm bolts!!! I have to lightly tap the new swing arm bolt into place on my Superbike frame. My machine shop then honed the inner swing arm sleeve to have only .001 thousands clearance between both. In the end I now had a swing arm and frame that had zero play between the two!!!! Just imagine if you have like .035 thousands side to side at the swing arm pivot point. How much side to side movement would you have at the rear axle!!!!! Same thing applies to the play in the motor mount bolts on the Kz1000 frames. If you run ream fit oversize bolts, the motor now becomes part of the frame.

I used to eyeball the factory Superbikes and check out all the things they did to their bikes. I would photograph everything on those bikes from end to end. Sometimes the factory guys got a little annoyed at me hanging around and taking so many photos!! The Honda guys were the worse in trying to get in the way of me taking some closeup photos. I got many of my ideas from just checking out the factory bikes. Why copy the bikes that run in like 10th place or so. You check out how the winning bikes did things!!!!

1972 H2 750 Cafe Racer built in 1974.
1976 KH400 Production Road Racer.
1979 Kz1000 MK. II Old AMA/WERA Superbike.
1986 RG500G 2 stroke terror.
1986 GSXR750RG The one with the clutch that rattles!

Up in the hills near Prescott, Az.
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Last edit: by Dr. Gamma.

What he said...measuring fork tubes 11 Sep 2019 23:25 #810733

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SWest wrote: How did you measure?
Steve


I used a digital micrometer I've had for years that is used for reloading. I measured the tube in multiple locations they seemed to remain constant.

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What he said...measuring fork tubes 11 Sep 2019 23:44 #810734

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DG, any idea on the size and quality of the PMC bolts? They look nice and are stainless steel or chromoly. Some are hollow.

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What he said...measuring fork tubes 12 Sep 2019 00:04 #810735

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Dr. Gamma wrote: Wait to you measure the clearance between the frame boss and the swing arm bolt!!!!!!! Then the clearance between the inner swing arm sleeve and the swing arm bolt!!!! One of the very first things I noticed on '79 factory Kawasaki Superbikes was a very non-stock looking swing arm bolt and nut. When I put the swing arm bolt through my Kz1000 frame I quickly saw why they used something besides stock parts. There was like .035 thousands or more of play between the two. Same with the inner sleeve too!!!!!


I just noticed that the police model has a different swing arm, it looks beefier and is braced more at the pivot. Will this fit on a KZ1000J/GPZ frame and or other KZ frames?

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What he said...measuring fork tubes 12 Sep 2019 02:28 #810737

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The take away I'm seeing here is remove any and all slop from the frame and suspension moving parts. So you probably don't have to drop a ton of money on exotic parts just make the stock ones work they way they should or stiffen them up and you should have a decent handling bike. Just my 2 cents.

577Nitro

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What he said...measuring fork tubes 13 Sep 2019 10:19 #810806

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577nitro wrote: DG, any idea on the size and quality of the PMC bolts? They look nice and are stainless steel or chromoly. Some are hollow.


My motor mounts bolts are just Grade 5 aircraft bolts. They are slightly oversize compared to the diameter of the stock metric bolts. I used an adjustable ream to open up the frame and the bosses on the motor where the bolts slide into. What you are looking for is zero clearance fit on all the motor mount bolts. My motor mount bolts have to be tapped in with a dead blow hammer. That way you are making the motor become part of the frame. Its the same as bracing that part of your frame. I don't think anybody still makes the thicker aluminium motor mount plates that I used on my bike.

The adjustable ream I used to open up my fame and motor to accept the oversize bolts.


The oversize motor mount bolts and thicker mounting plates installed on early Kz1000 frame.
1972 H2 750 Cafe Racer built in 1974.
1976 KH400 Production Road Racer.
1979 Kz1000 MK. II Old AMA/WERA Superbike.
1986 RG500G 2 stroke terror.
1986 GSXR750RG The one with the clutch that rattles!

Up in the hills near Prescott, Az.
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Last edit: by Dr. Gamma.

What he said...measuring fork tubes 13 Sep 2019 12:47 #810809

  • TexasKZ
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Though not identical, D&G still list billet motor mounts.

www.dgchassis.net/Dragbike%20Motor%20Mou...ike-motor-mount.aspx
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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What he said...measuring fork tubes Yesterday 01:49 #810856

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Dr. Gamma wrote:

577nitro wrote: DG, any idea on the size and quality of the PMC bolts? They look nice and are stainless steel or chromoly. Some are hollow.



The oversize motor mount bolts and thicker mounting plates installed on early Kz1000 frame.


PMC sells the Aluminum billet mounts as well, I just ordered a set from webbike.jap. PMC appears to have a huge array of vintage performance parts, including many S1 replica included. They, I think, are a major supplier of bits for the great AC Sanctuary builds. I have a pretty big order of pieces from them coming in . One thing is an adjustable side stand that is longer and straight so it will tuck up under the frame out of the way of the S1 rear sets I have.

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