1983 Katana 1100 Race Build

[D Nuts]

Vintage racing in my area allows for swing arm, fork & rim mods but they must come from machines 1982 or prior. A priority for my is running 17's front & back & I'd like to run a 120/180 combo to I can use quality rubber. I also want a Superbike Bar instead of clip ons.

I wouldn't mind shortening the swing arm so the bike will turn easier. (I know gsxr is viable, but that's 85 + & can't be used).

I must run dual shocks & may go for Ohlins. I'd also wouldn't mind a digital tach. I must also use the same # of piston brakes.

These are some of the things I can think of that are linked together / affected that should be considered.

Does anyone have any viable ideas that will qualify?

Thanks for your help

[El Giablo]

Vintage racing in my area allows for swing arm, fork & rim mods but they must come from machines 1982 or prior. A priority for my is running 17's front & back & I'd like to run a 120/180 combo to I can use quality rubber. I also want a Superbike Bar instead of clip ons.

I wouldn't mind shortening the swing arm so the bike will turn easier. (I know gsxr is viable, but that's 85 + & can't be used).

I must run dual shocks & may go for Ohlins. I'd also wouldn't mind a digital tach. I must also use the same # of piston brakes.

These are some of the things I can think of that are linked together / affected that should be considered.

Does anyone have any viable ideas that will qualify?

Thanks for your help

This may help. El G.

[D Nuts]

Sweet. What type of forks, swingarm and rims? Mine have to be 1982 or older. thanks

This may help. El G.

[GregT]

First off, where are you and what organisation are you going to race with ?
Around the world - certainly Europe,Oz and NZ - 17in rims are allowed in pre 82 classes but usually in limited widths.Typically 3.5in front and 5in rear. period 17's are certainly available - but too narrow for current rubber.
If you are indeed limited to period rims then stay 18in - there is some very good (but expensive) rubber available - Avons in particular do race rubber in 18's.
Brakes - again period limitations are usually 2 piston calipers which means Lockheed or Brembo 08's - usually there's a disc diameter rule too.
Swingarm - use a GSX1100 alloy arm and brace it. Light and stiff.
Shocks - there are cheaper options than Ohlins.

What are other people in your class using - always a good starting point.

[El Giablo]

Sweet. What type of forks, swingarm and rims? Mine have to be 1982 or older. thanks

Stock fork, Cal-Fab swing-arm, Dymag wheels. El G.

[streetfighters]

180 size tires were not even invented in 82. Can you use slicks or should tyres be DOT? Are you sure they can be used in this class?
Also, Kawasaki Z-1 / KZ swingarms were shorter but again no room for 180 rubber and as rigid as a boiled noodle in standard form. They can be braced though if allowed.
I'd nail down the allowed mods prior to buying parts. No sense in building a great bike only to be DQ'd at tech insp., right.
streetfighters

[D Nuts]

Im in Ontario, Canada. VRRA

I have a difficult time reaching the tech guy and only 1 person races this model and I have msg'd him and waiting to hear back from him. Its going to take a while to get this project done and waiting for a week (or weeks) for just 1 reply really slows the process down (not to mention finding parts isnt a walk in the part). Ive read the rules numerous times and Ive never raced Vintage before and the list of rules are alot longer and it me, sometimes unclear. Things were more simple racing current bikes. I dont think im permitted to use GSXR components as they are 85+.

First off, where are you and what organisation are you going to race with ?
Around the world - certainly Europe,Oz and NZ - 17in rims are allowed in pre 82 classes but usually in limited widths.Typically 3.5in front and 5in rear. period 17's are certainly available - but too narrow for current rubber.
If you are indeed limited to period rims then stay 18in - there is some very good (but expensive) rubber available - Avons in particular do race rubber in 18's.
Brakes - again period limitations are usually 2 piston calipers which means Lockheed or Brembo 08's - usually there's a disc diameter rule too.
Swingarm - use a GSX1100 alloy arm and brace it. Light and stiff.
Shocks - there are cheaper options than Ohlins.

What are other people in your class using - always a good starting point.

[D Nuts]

I didnt think there was a restriction on tires, just rim size and the rubber has to be appropriate for the rim (my understanding of the rules). Slicks are permitted in Period 4 (my Kat is period 3). This is my problem, my inability to get clear info from the tech guy and the rules are extension, but not clear in my mind (but it could be because i have no experience with vintage racing)

180 size tires were not even invented in 82. Can you use slicks or should tyres be DOT? Are you sure they can be used in this class?
Also, Kawasaki Z-1 / KZ swingarms were shorter but again no room for 180 rubber and as rigid as a boiled noodle in standard form. They can be braced though if allowed.
I'd nail down the allowed mods prior to buying parts. No sense in building a great bike only to be DQ'd at tech insp., right.
streetfighters

[GregT]

I've had a look at your rules and they're about the same as ours in NZ.
You're limited to 3.5in front and 4.5in rear but allowed 17's both ends.
Solid spoke mags too which is a bit picky IMO....CBR600 wheels should suit you there.
Two piston calipers like us and 300mm disc size and effectively non floaters too, same as us. I'm using Brembo 08's on 296mm CB1000F discs mounted on machined alloy centers. The Brembos are readily available and way cheaper than Lockheed's.
Swingarm - as I said use a GSX 1100 arm which is what you North Americans know as a GS1100 - the 16v version has an alloy arm which is correct period and can be braced too.
If you're serious use Keihin CR roundslides which are allowed where I doubt flatslides are.
Tyres - treaded 17's Michelin or the new Metzeler's seem to be the pick but it depends if you are allowed tyre warmers. If not try Michelin pilot 2ct.
Vintage - or post classic racing as we know it is fun and I'm sure you will enjoy it. You're starting from a good point too with the Kat.

[D Nuts]

Wow. Thanks so much for offering so much help! Really appreciated. I have heard many good things about the VRRA, but I'm just having a bit of a hard time reaching the tech guy and my experience with Vintage is zero, but I'm really pumped about checking off this "bucket list" item for myself.

If I were to find a GS1100 swing arm, would that be 81 or 82 (there was a model change up here in 82, but im not sure whether it affected the swingarm. Would CB1000F disks mount on CBR 600 rims ok? Will a 4 1/2 rim handle a 180 ok? What your CBR 600 would you suggest? Are there different models of Brembo 08's needed to fit the swingarm? Do I need to purchaseBrembo caliper brackets and master cylinder or will they work with oem (just bolt on)? Should I be looking at a rear caliper upgrade (I think it maybe the 09)? When I order my Ohlins shocks, would I order the model for my 83 Katana 1100 or for the GS1100 model? Someone I spoke to suggested that I raise the rear and try to go with a longer shock (Im not sure how this will affect wheel base or geometry, but a shortest wheel base would turn nicer (I think OEM was 60 inches). A for carbs, it states "
6d. CARBURETORS: Must be of style and type used within period including flatslides". Fork suggestions? Should I stay with OEM and accomodate a 17 rim that can take a 120? Id like to convert to superbike bar so this is a factor for the fork set up I think.

As far as cooling, Ive been searching on line for a bolt on oil cooler (I have a Lockhart Phillips years ago and it worked fine for the street), but I dont know of any other brands that still produce something viable and effective. Thanks so much for your help!

I've had a look at your rules and they're about the same as ours in NZ.
You're limited to 3.5in front and 4.5in rear but allowed 17's both ends.
Solid spoke mags too which is a bit picky IMO....CBR600 wheels should suit you there.
Two piston calipers like us and 300mm disc size and effectively non floaters too, same as us. I'm using Brembo 08's on 296mm CB1000F discs mounted on machined alloy centers. The Brembos are readily available and way cheaper than Lockheed's.
Swingarm - as I said use a GSX 1100 arm which is what you North Americans know as a GS1100 - the 16v version has an alloy arm which is correct period and can be braced too.
If you're serious use Keihin CR roundslides which are allowed where I doubt flatslides are.
Tyres - treaded 17's Michelin or the new Metzeler's seem to be the pick but it depends if you are allowed tyre warmers. If not try Michelin pilot 2ct.
Vintage - or post classic racing as we know it is fun and I'm sure you will enjoy it. You're starting from a good point too with the Kat.

[Buffalo Bill]

“Will a 4 1/2 rim handle a 180 ok?”

NO, you're limited to 160.
Go to Michelin.com and download their Motorcycle Tire Fitment Guide.
You might find the Michelin sales rep for VRRA on their forums, and ask him what's best.
Best 'O luck!
Bill

[amxsteve]

i have an 82 1100E swingarm you can have for FREE come and get it.I am in Tottenham/Ont about 90 min from u. have lots of other parts too

[TheCafeKid]

You don't want a tire that's too wide for the rim. It eats up effective contact patch on center, when you're putting the power down, (also the smallest point of contact in ratio to the rest of the tire) and it will also slow handling.
With those rim limitations stick with a 150-160 rear and a 110 in front. The GS1100 swinger went the same from 80-83 so no worries there and an 18x4.5 rim and tire combo will fit without trouble. Any limitation on chain pitch/type?

For your forks stick with stock Kat fork or an 82 GS1100E fork. They have some damping adjustment built into them. Unless you're allowed cart
Emulators. Then go with those. Good springs, a period brace, and as much damping adjustment as you're allowed and you'll be fine. They're smaller diameter than later forks, but the walls are thick. Thicker than some modern stuff. Where you'll want to worry about flex is the frame. You allowed to brace it?

[GregT]

Somewhere on here is a build thread for a GS1000 for VRRA. A lot of what he did is applicable to your Kat, particularly wheel and brake transplants and frame bracing.I'm sure someone better at it than me will post a link.
If you do go to the Brembos you'll have to make up the mounting hardware to suit whatever discs you finish up using.
The 08 Brembos were used on a lot of continental stuff - on BMW's up to recently. BMW ones come up on ebay frequently. Use a 14mm mastercylinder and you'll do stoppies....
Discs are a problem in that you want as big as possible - but as thin as possible (5 mm is good and common) then you have to adapt them to the wheels you use.Vintage racing done seriously is not an easy game.
Cafekid is on the right track with forks. I see your rules allow later RWU forks to a max of 41mm OD - sure saves hunting for GL1000 forks in good condition which is what happens here.
Shocks - you buy Ohlins or similar by length...our GS1000 is running 360mm long Gazi shocks which are an Ohlins copy. There's usually alternative length clevis ends available. Supply details of your weight when you buy as they can give you springs which will be in the ballpark.
No chain size rules so convert to 520 for tyre clearance.
Back brake is best converted to an underslung mount using the std caliper as the GS1100 top mount gives tyre clearance problems. If you use the smaller disc which will probably come with the 17 rear it's a weight saving.

As you'll see from the answers there's plenty of help available here - and you haven't heard from the Aussies yet - they're probably still hungover from the weekend's Rugby and MotoGP....Have a look at Sharpie's pics and posts.

[D Nuts]

Im was pretty sure a 17 inch 3.5 inch front would be good with a 120/70. I wasnt sure if i could use the stock forks, CB1000F rotors and the Brembo F08's all together. I'm looking for a set of F2 rims now 160/60 for the rear as well and Im gonna pick up the 82 GS1100 swingarm this week thats to Steve who lives only about an hr or so away from me (thanks Steve!) And, thanks alot Greg for schooling me

Somewhere on here is a build thread for a GS1000 for VRRA. A lot of what he did is applicable to your Kat, particularly wheel and brake transplants and frame bracing.I'm sure someone better at it than me will post a link.
If you do go to the Brembos you'll have to make up the mounting hardware to suit whatever discs you finish up using.
The 08 Brembos were used on a lot of continental stuff - on BMW's up to recently. BMW ones come up on ebay frequently. Use a 14mm mastercylinder and you'll do stoppies....
Discs are a problem in that you want as big as possible - but as thin as possible (5 mm is good and common) then you have to adapt them to the wheels you use.Vintage racing done seriously is not an easy game.
Cafekid is on the right track with forks. I see your rules allow later RWU forks to a max of 41mm OD - sure saves hunting for GL1000 forks in good condition which is what happens here.
Shocks - you buy Ohlins or similar by length...our GS1000 is running 360mm long Gazi shocks which are an Ohlins copy. There's usually alternative length clevis ends available. Supply details of your weight when you buy as they can give you springs which will be in the ballpark.
No chain size rules so convert to 520 for tyre clearance.
Back brake is best converted to an underslung mount using the std caliper as the GS1100 top mount gives tyre clearance problems. If you use the smaller disc which will probably come with the 17 rear it's a weight saving.

As you'll see from the answers there's plenty of help available here - and you haven't heard from the Aussies yet - they're probably still hungover from the weekend's Rugby and MotoGP....Have a look at Sharpie's pics and posts.