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Discussion Starter #61
Some things to consider when building a racer or cafe race from these tube frame big motor bikes. We have built several for vintage racing and are now in the process of putting together a pair of Suzuki GS1100E's These are going to look close to the Yosh motorbikes ridden by Graeme Crosby.

First off the frames do flex especially with the modern rubber we can use now days. You can brace the chassis but you can't get all the flex out. One thing we found is that very wide rubber is not the best way to go (we're working with 160 rears) because you overload the chassis and the frame winds up and then springs back . Feels creepy ! So what we have been trying is to use the lightest wheels (because of rules no CF) we can find. We brace the swingarms, We also are using the best 41 mm forks we could find (USD forks are NFG by rule) with fork braces and Ohlins cartridges. By the way Ohlins cartridges in the Showa forks work great (we ran them at the Isle of Man Manx GP) without any problems and they're going to cost you $1200.00 less.

We use Ohlins dual shocks because that's what Yosh used back in the day. They are not perfect and don't work quite as well as the modern single shock but then again these aren't modern motorbikes are they ? You can make the dual shocks work they take a wee bit more fussing with and you need to take care to keep records of your changes if for no other reason than it keeps you keeping your changes clear side to side.

Also remember you will never be able to lean these puppies over like you can a modern sport bike cause shit will jit the ground. We had an old Muzzy SBK here and there were all kinds of work done to the cases to allow for more clearance while leaned way over. I don't know if it was Muzzy's guys or someone else but it looked good and did allow more angle. Also looked to be a ton of effort put in to it.

So my advice. Get the weight down, stiffen the swing anr and chassis, find modern wheels, and spend your money on good fork innards,and shocks...............Then ride the hell outa the thing.

Cheers
Rich
So what did you have to do to fit the 160 on the rear? And I have no intention of building a race bike I just want to build something that performes better than before and looks the way I want so what did you do specifically to your swingarm?
 

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So what did you have to do to fit the 160 on the rear? And I have no intention of building a race bike I just want to build something that performes better than before and looks the way I want so what did you do specifically to your swingarm?
If you look up pictures of braced swingarms on vintage bikes (AHRMA or WERA or the Isle of Man) you can see how they do it... basically a U-shaped tube connected on the underside o fthe swingarm near both shock mounts with two or so "struts" near the pivot.

If you want a suspension that performs better than before; racetech emulators and springs on the stock shocks along with a good fork brace. including machining it will cost you about $400?
 

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So what did you have to do to fit the 160 on the rear? And I have no intention of building a race bike I just want to build something that performes better than before and looks the way I want so what did you do specifically to your swingarm?
He has to comply with competition class rules, you can just replace it with a better one or fabricated one IF the drive chain can be made to clear the wide tire.

The sensation he is describing it's like having a rubber hinge in the middle of your bike. You might never push your frame that hard on the street, unless you ride fairly um spirited.

.... what's the distance from the centre of your rear hub to the centre of the sprocket?
 

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Discussion Starter #64
I found a guy who fans supported swing arms and its 3-5/8" from center hub to center sproket
 

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Discussion Starter #66
This is a pic of one swing arm conversion he did but I can send him my swing arm he can strut it and send it back with caliper brackets and everything for 160 so I think I'm going with that route he said it supports a 180 back tire
103346
 

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You likely won't find a better sounding board for ideas then guys like Rich that have pounded them round the IOM. It's a place that will point out a bad idea very quickly.
Woodman,
Just to clarify I am the wrench spinner. My riders are mates named Wade Boyd and Eric Lindauer. Wade has over 50 IOM starts most on solos but some on three wheelers. In fact there's a small private garden on riders right just before the Ramsey Hairpin where Wade launched his wife and passenger a few years back. We now refer to this spot as Christine's Garden.
Regards
Rich
 

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Woodman,
Just to clarify I am the wrench spinner. My riders are mates named Wade Boyd and Eric Lindauer. Wade has over 50 IOM starts most on solos but some on three wheelers. In fact there's a small private garden on riders right just before the Ramsey Hairpin where Wade launched his wife and passenger a few years back. We now refer to this spot as Christine's Garden.
Regards
Rich
All the more reason for him to pay attention. Not many places demand as versatile suspension as the IOM.

I always find it interesting that the "cafe"/pipeburn builders never mention riding their visions.
 

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This is a pic of one swing arm conversion he did but I can send him my swing arm he can strut it and send it back with caliper brackets and everything for 160 so I think I'm going with that route he said it supports a 180 back tire
Not with a chain it won't, you are pushing it with the 160, a 180 is 7+ inches wide, do the math.
... that swingarm isn't strutted, it's of a semi-modern bike, I could get one that good or better at the scrap yard for 50 bucks canadian.

wtf did he do to the rear half of the frame, that's terrible don't do that.
 

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Discussion Starter #71
That's not my bike or my setup just en example of a custom swing arm a fabricator sent me as an example
 

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Fabricated is a good term for it, the rear is something right out of a scrap yard with a hot front end hanging off it. It's going to ride like it has a rubber hinge in the middle.

... by the way did you notice how limited those USD forks make turning the bars, the bikes going to have a 25 foot full lock turning radius :rolleyes:
 

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This is a pic of one swing arm conversion he did but I can send him my swing arm he can strut it and send it back with caliper brackets and everything for 160 so I think I'm going with that route he said it supports a 180 back tire View attachment 103346
Now if he were to build a frame that worked with that front and rear he would have a good rolling chassis.
 

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Might as well just go buy a real bike,
that's a monoshock rear end that has been turned into a twin shock with about 3 inches of shite shock suspension travel and it's not complete for a reason the rear tire is a burnout and the front everything is too nice to be off anything that was legitimately scrapped.
 

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There is no listing because Ohlins doesn't and never has made forks for Kawasaki cruisers.

Measure from your top triple to the bottom of the tire. Find a bike with USD forks that has the same measurement. Buy the forks, wheel, rotors, calipers, upper and lower triples. Go to All Balls conversion charts and find the appropriate bearings for your conversion. Put the entire front end on your bike.
You might try some Showas, WPs, from Ducati Multistrada or KTM Adventures. They're long, have the modern brakes and have reasonable triples that aren't too ugly. You might get lucky and have close to right stem. I got the front end from a 390 KTM Duke that only required a kit from All Balls that had the right races to press into the frame and the axle was the right diameter for my S40 Boulevard. I wanted some longer forks for my Monster that got through the triples that allowed clip ons to be mounted above the triples. I found a set of Ohlins off an 04 Multi that fit the bill. They actually had to be shortened a bit to be perfect. It's not as hard or expensive to shorten versus lengthen. Keep your eyes peeled on ebay and buy as complete as you can.
 

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As far as the discussion relating to tire size. We were very lucky in that after we fitted the CB600 wheels F/R we had enough clearance to fit 160 Race rubber on the rear. If I remember correctly you can go to A.P.E. and they make a spacer set up so you can even get a 180 on the bike. As I said before bigger is not always better. People tend to think wider tire more rubber on the deck but if wheels don't accommodate the size then the foot print goes to hell and the bike feels wonky. On our GS1100E Classic SBK we will even be testing with a 110/ front as it may help turn-in.

After racing cars for years when I started building race bikes for mates the big difference between cars and bikes was feel. I did a lot of testing, my cars and other peoples. In a car I could (if I had to) work around almost any handling problem. NOT TRUE FOR MOTORBIKES! Even the fast guys can't go real quick if the bike does things they don't like.

So what I 've learned when it comes to bikes is don't get caught up with what's cool or the new trick thing. Make the bike feel right for you, Hell it's often even cheaper.

As far as the swing arm bracing it does make a noticable difference in feel on the rear. It is also important to make sure the pivot bearings are in good order. You'd be surprised how many time I've found the bearings or bushing worn out or even gone all together. The other often overlooked thing is being sure the chain (keep in mind that the chain is sort of part of the suspension) is the proper tension (make sure you weight the bike when checking) and is running true and straight. Oh ! and remember the marks on the chain adjusters often don't mean crap. I use a laser pointer and always double check that the rear tire is straight in the swing arm. If you don't the bike feels different on left v's right turns.

Cheers
Rich
 
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