82 Kat resto-mod aka Project Bucket Case

[ukilme]

You have quite an angle on your swing arm M8. The shock mounts are too far forward. You are going to find that your chain will be sawing through your pivot. If you haven't already bought your offset sprocket I would suggestyou try a 19t front and a 51 tooth rear. Sounds big I know, but in actuality they are the same diameter as the stock 630 that came off it. Give or take a mm or two. Check it out and make sure your chain clears.

cheers,

Ya, I am a little worried about the chain rubbing agaisnt the swing arm. I figured I could use a larger front and rear but damn 19/51 is big. But if is the same diameter of the stock 630 sprockets then it won't be to bad.

I was trying to go for between 25-26 degree rake which it is but I wasn't think far enough ahead. And yes, I do plan on a damper. I have not decided how to go with it.

Now, with the engine in the frame, the shock will compress the shocks a bit. Would this help a little with the issue?

[ukilme]

This is true (better than just sliding the axle all the way forward) but it does not center the rear wheel on the Rear axle.

Agreed it does not center the wheel on the axle but it will help the z and y axis. If I got my terminology right.

[katman]

With a .650 spacer the rear wheel is centered in the frame. This is how I have arrived at this conclusion.

have drill rod through my steering stem and swingarm pivot. I have measured both triangles which showed me that the neck is straight in relation to the pivot. Reason being the distances are exactly the same with each side of the triangles.
I then measured from the pivot rod to the center of the rear rim. With the numbers from each end of the drill rod through the pivot being equal to the mm, you have to use a .650" spacer on the sprocket side.

This aligns the front and rear wheels in my frame. It aligns the wheels with the center line of the bike and it requires the custom offset front sprocket to align the chain. All said and done, for the kat and bandit arm, everything is at least as straight as from the factory. I am most confident in these numbers.

[ukilme]

I think ukilme is doing a good job, but I just did not see where he established the (#1) first part of the alignment procedure which is to insure that the rear wheel is located properly on the rear axle.

The offset of the wheel to the forks needs to counter the offset between the center of forks and the frame pivots so the wheel is on the centerline. I think 3/16" is the offset. This is done with R axle spacers.

1-2mm accuracy is fine

Once this is done then (#2) the rear to front wheel alignment is done (adjusting axle adjusters)

finally the (#3) offset sprocket to get the chain in alignment.

Maybe this will help and you can let me know if I am doing it wrong which is what this thread is about.

I started with a straight frame. I checked it out when I bought it and my welder check it out when I got the bracing done.

Next, I got a complete 93 gsxr750 front end including the spacer, speedo, a 93 gsxr front wheel and even the brakes ect. Now, I did use a 02 CBR 954 tree but the spacing is the same. My thinking with this combo means that front wheel will be centered to the frame.

With the front wheel mounted, I made sure the forks were not out of line and the wheel was correct with the 3 axis-again, I hope my terminology is right.

This means my front wheel is a known at least to my thinking and the rear is the unknown

Now, the rear rim is a 93 gsxr750 rim as well. This meant that stock B12 spacers are the same (part number 64741-17e00/left side and 64751-46e00 the right side). With these spacers, I could mount the rear and make sure the front rim straight ahead. From here, I figured out the rear wheel spacer.

So, basically I work from my known (the front) to the unknown (the rear) which should take care of offsets. However, if I would have another unknown rims (R1, even B12) then I would have center the rear first.

Also, as I was using the laser to check the alingment. I was able to measure the laser along the frame especially at the cross member and the the distance was pretty much the same as the wheel alignment. About 1mm difference.

Let me know if I did this okay. You both, Katman and posplayr, know more about this then myself

And thanks for your advice and questions.

[katman]

Yur doin it all right Bubba. Best to air it out now and correct than after it is built.

[posplayr]

With a .650 spacer the rear wheel is centered in the frame. This is how I have arrived at this conclusion.

have drill rod through my steering stem and swingarm pivot. I have measured both triangles which showed me that the neck is straight in relation to the pivot. Reason being the distances are exactly the same with each side of the triangles.
I then measured from the pivot rod to the center of the rear rim. With the numbers from each end of the drill rod through the pivot being equal to the mm, you have to use a .650" spacer on the sprocket side.

This aligns the front and rear wheels in my frame. It aligns the wheels with the center line of the bike and it requires the custom offset front sprocket to align the chain. All said and done, for the kat and bandit arm, everything is at least as straight as from the factory. I am most confident in these numbers.

Rob,
Interesting setup. That does confirm your overall frame alignment . . I think it is valid for the following combination:

• 5.5"x17" 2nd Gen GSXR rear wheel
• GS sprocket carrier
• Bandit swingarm centered in the pivot bosses

I'm using a different wheel, carrier and swingarm offset so mine is different.


Just as a double check I would measure the wheel position inside of the swinger forks and see if you get the right offset.


Jim

[posplayr]

Maybe this will help and you can let me know if I am doing it wrong which is what this thread is about.

I started with a straight frame. I checked it out when I bought it and my welder check it out when I got the bracing done.

Next, I got a complete 93 gsxr750 front end including the spacer, speedo, a 93 gsxr front wheel and even the brakes ect. Now, I did use a 02 CBR 954 tree but the spacing is the same. My thinking with this combo means that front wheel will be centered to the frame.

With the front wheel mounted, I made sure the forks were not out of line and the wheel was correct with the 3 axis-again, I hope my terminology is right.

This means my front wheel is a known at least to my thinking and the rear is the unknown

Now, the rear rim is a 93 gsxr750 rim as well. This meant that stock B12 spacers are the same (part number 64741-17e00/left side and 64751-46e00 the right side). With these spacers, I could mount the rear and make sure the front rim straight ahead. From here, I figured out the rear wheel spacer.

So, basically I work from my known (the front) to the unknown (the rear) which should take care of offsets. However, if I would have another unknown rims (R1, even B12) then I would have center the rear first.

Also, as I was using the laser to check the alingment. I was able to measure the laser along the frame especially at the cross member and the the distance was pretty much the same as the wheel alignment. About 1mm difference.

Let me know if I did this okay. You both, Katman and posplayr, know more about this then myself

And thanks for your advice and questions.

Personally I would not try and reference off the front fork as there is no good way to tell when the front fork is straight in the frame.

What Rob and I were trying to figure out before and I think he had already arrived at the 0.650" before was how to confirm the rear wheel spacer that centered the rear wheel.

He had confirmed that by simply measuring how much offset the swing arm has ( 3/16" in the case of Bandit swingarms) and positioned the rear wheel (trial and error ) until the offset of the wheel between the rear swing arm forks is offset to match. He also used depth gauges which I tried also to duplicate but never felt too confident in all the translations.

I used some similar results to modify my rear spacer with even a few more twists.

Unless you can duplicate what Rob did, the simple measurement is get the wheel offset in the fork to compensate for teh swingarm offset. I used a T square to measure my offset.

[katman]

I rigged up a laser see how it may turn out. The holder is machined with a lathe and a mill so it is acurate. My laser is also fine tuned and checked between my chuck and dead center on the lathe. The two hangers were machined as well on the lathe.

I aligned the laser on the pivot bolt with the point of the drill rod through the steering head and I tightened the set screw. I was then able to rotate the laser front to back. I followed the dot up the drill rod and across the frame main back bone that the tank sits on. As I ran it back to the rear wheel it again confirmed my last measurements.
As Jim said,

This is for a 5.5 straight spoke wheel
bandit swingarm
gs1100 sprocket carrier

My checks on the chain alignment shows a .465" offset front spocket. I get them made for 79.00 any tooth and pitch. This setup gives you .160" (4mm) more room for the chain to get past the frame.

[ukilme]

Personally I would not try and reference off the front fork as there is no good way to tell when the front fork is straight in the frame.

What Rob and I were trying to figure out before and I think he had already arrived at the 0.650" before was how to confirm the rear wheel spacer that centered the rear wheel.

He had confirmed that by simply measuring how much offset the swing arm has ( 3/16" in the case of Bandit swingarms) and positioned the rear wheel (trial and error ) until the offset of the wheel between the rear swing arm forks is offset to match. He also used depth gauges which I tried also to duplicate but never felt too confident in all the translations.

I used some similar results to modify my rear spacer with even a few more twists.

Unless you can duplicate what Rob did, the simple measurement is get the wheel offset in the fork to compensate for teh swingarm offset. I used a T square to measure my offset.

What do you mean by straight? Are you talking, fork pinching, forks being parellel to the center line or offset to the center line?

I guess the method I used can lead to more errors then Rob and yours. But the good news is I can still double check it before I mount the motor.

Jim, didn't you get your top hat spacers offset? Or am I thinking of someone else? I just got the standard top hat spacers from Rob.

And Rob, I will most likely hit you up for the sprocket as a 18 or 19 tooth sprocket is not easy to come by. And I love the tools that you make that center line tool is really cool.

[posplayr]

What do you mean by straight? Are you talking, fork pinching, forks being parellel to the center line or offset to the center line?

I guess the method I used can lead to more errors then Rob and yours. But the good news is I can still double check it before I mount the motor.

Jim, didn't you get your top hat spacers offset? Or am I thinking of someone else? I just got the standard top hat spacers from Rob.

And Rob, I will most likely hit you up for the sprocket as a 18 or 19 tooth sprocket is not easy to come by. And I love the tools that you make that center line tool is really cool.

The forks are straight when the front wheel lies in a plane parallel to a vertical plane running through the centerline of the frame. Assuming the frame is straight, this occurs somewhere along the line as you turn the handlebars from left to right. The question is where and it is hard to measure unless you can somehow lock down the front fork.

[ukilme]

The forks are straight when the front wheel lies in a plane parallel to a vertical plane running through the centerline of the frame. Assuming the frame is straight, this occurs somewhere along the line as you turn the handlebars from left to right. The question is where and it is hard to measure unless you can somehow lock down the front fork.

Got it. That's what I tought you meant. Thanks.

[katman]

That is where the drill rod and a couple cones come in handy

[posplayr]

What do you mean by straight? Are you talking, fork pinching, forks being parellel to the center line or offset to the center line?

I guess the method I used can lead to more errors then Rob and yours. But the good news is I can still double check it before I mount the motor.

Jim, didn't you get your top hat spacers offset? Or am I thinking of someone else? I just got the standard top hat spacers from Rob.

And Rob, I will most likely hit you up for the sprocket as a 18 or 19 tooth sprocket is not easy to come by. And I love the tools that you make that center line tool is really cool.

Rob and I went around and around chasing down what I think was just measurement error on the measurement in wheel spacers for a Bandit arm. In the end I used his original numbers although I did a variation to offset the swingarm to use the stock rear brake setup. I have a single 1.0" spacer sprocket side with all stock 88 GSXR 1100 wheel/sprocket carrier/brake arm.

I tried to confirm the rear wheel spacing by using a straight edge from the front wheel back to the rear wheel (with the frame upside down) and the distance is just too great to get an accurate read. My straight edge was good to about 1/2 mm in 8 ft, but that was not the issue.

That is why I recommend the following steps:

1.) center the Rear wheel with the proper spacers (1-2mm tolerance)
2.) string adjust rear wheel to align with front wheel (4 measurements FB of both left and right rotor) (1-2 mm)
3.) align the chain with counter sprocket/surfacing sprocket carrier (1 mm.

[ukilme]

I used a 8 foot metal level that was straight to make sure the front wheel was aligned and took my measurements from the rim.

I have today off, so, I'll double check the wheel and see if it is centered.

NOw, I have a question with regards to the swing arm. I realize you, guys, wouldn't have done it the same way, but would you use it or redo it?

As Rob mentioned, the mounts are pretty far forward and gives me about 25-26 degrees overall rake and stock Katana is around 28 degrees. I was going for a little more rake and not even thinking chain clearance with the swing arm.

So, the issue are chain clearance which can be fixed with custom sprocket (cross my figures) and the mounts themselves. While strong and similiar designs used by others, can be made stronger even if the shock are square.

[posplayr]

I used a 8 foot metal level that was straight to make sure the front wheel was aligned and took my measurements from the rim.

I have today off, so, I'll double check the wheel and see if it is centered.

NOw, I have a question with regards to the swing arm. I realize you, guys, wouldn't have done it the same way, but would you use it or redo it?

As Rob mentioned, the mounts are pretty far forward and gives me about 25-26 degrees overall rake and stock Katana is around 28 degrees. I was going for a little more rake and not even thinking chain clearance with the swing arm.

So, the issue are chain clearance which can be fixed with custom sprocket (cross my figures) and the mounts themselves. While strong and similiar designs used by others, can be made stronger even if the shock are square.

I added about 1" to my shock length to increase the rear ride height. It is hard to do that without spending a lot of money on shocks. 1" is a pretty common increase. How high do you figure you have raised the rear with relocation of the shock mounts?


If you remember the law of sines (a little trig) we can compare your swingarm angle to mine. You would need to measure the following three distances:

L1-swing arm pivot to rear axle (center to center)
L2-top shock to swingarm pivot
L3-top shock mount to rear axle

The ride height difference between yours and mine will be approximately
del_height = Sin (theta 3_yours-theta3_mine) *L1