AHRMA Vintage Heavyweight Superbike Build

[Outlaw4shrt]

So before the flaming begins, I fully acknowledge that an XS1100 is not, nor really ever intended to race in a 1025cc displacement limited vintage superbike class. Having said that, on Wednesday I had a really great and long conversation with Thad Wolff who is on the AHRMA Vintage Superbike eligibility committee about my bike. I reached out to him and a couple other board members, and sent some pictures and a description of my bike and Thad got back to me. He was satisfied with the work converting my bike to chain drive and really excited about the possibility of having a Yamaha run in the class!

Below is a picture of my bike from a mock-up a while ago and is "generally" how it looks now. It is one of the pictures I showed Thad and will help explain some of the discussion points below.


A few of the talking points:
1. The chain drive conversion is a go! He liked the work that I had done and was satisfied with the welds (from what he could see in the pictures). His only concern was me changing the location of the swingarm pivot mount. He didn't like that I had changed it from the stock location. I moved it 2 inches forward and an inch down to shorten the wheelbase and to bring the swingarm itself down so I would have fewer issues with it clearing the chain during articulation. He didn't think it was going to be a deal breaker, but emphasized that I needed to pay very close attention to the rulebook and follow it as closely as possible to ensure eligibility.

2. The motor... So what he said is that the class guidelines are engines displacement limited to 1025cc, however, they aren't asking people to break engines open and my eligibility will really be based on if they receive a complaint about my bike or if it showed up sounding really angry/a fire breathing monster! Now, my motor is not stock, but I am running a stock cam (78'), stock carbs, and 87 octane non-ethanol gas. Based on some of the KZ's and GS's I've seen run in the class, I don't think having too much power is going to be an issue for me and I expect it to be quite the opposite. Having said that, depending on how this build goes and if I actually make it out on track, the goal would be to build a class legal motor for next year.

3. The look of the bike is going to be really important. That said, and I quote "it needs to not look like a rat bike!" and I respect that. That was never the plan anyway, and I will be painting the tank and seat and the bike will be really clean.

Alright, gotta head back to work, MTF...

[Outlaw4shrt]

continued from above.

3. Having a clean "period" looking bike arguably is one of the most important aspects of making it though tech. As far as the look goes, he wasn't happy about the seat that I have on there. He understood why I choose a different one since the original one for my 81H was a massive king and queen seat, but I need to put a 78 or 79 standard seat on it. Also, I need to run the stock gauges as well, which I have but haven't mocked up yet.

4. AHRMA rulebook. So I do need to make significant changes to the components on the bike:
- My bike currently has 43mm FZ1 works with 4 piston calipers and I need to downgrade to no larger than 41mm forks with single or dual piston calipers. Luckily I have an 88 FZR1000 with 41mm forks and 2 piston calipers sitting in the garage so that won't be too bad. I need to try and take the cartridge kit out of the FZ1 forks and put them in the FZR forks though.
- He didn't like the rear swingarm as it was too modern, and I need to switch to an older boxed aluminum swingarm or run a steel tubular swingarm from like a ZRX1100. Additionally, my current rear wheel is 5.5" wide and I need to go down to a 4.5" wide rim. Getting this done is going to be more of a challenge. I'd like to keep only Yamaha components on the bike, but I can't find a Yamaha 17x4.5 wheel from the period and then I'd have to come up with a Yamaha swingarm that would work. I have a local salvage place and they have an 86 FZX700 swingarm that might work, and they have a bunch of Suzuki katana 17x4.5 wheels so hopefully I can make that work. I think this is going to be the most challenging aspect of the build now (aside from just getting the bike running).

Overall, I need to:
- put some rear sets on for more cornering clearance. I'm going to pull the ones off my FZR which are nice actually because the rear brake master cylinder is built into the rear set and I think they will work out nicely. I'm going to pull them off this week and see if I can't get them mocked up and bungs welded for them.
- find some paint and make it look as nice as I can and finally get the frame powder coated.
- have a 4 into 1 exhaust, I'm not sure which brand, that I need to mock up and get a muffler for.
- weld bungs for the XJR1300 oil cooler that I have.
- come up with a solid carb and intake set-up. I think I'm going to drop the airbox and try to run velocity stacks. (is that a good idea or would it make more power on the stock carbs with the stock airbox?)
- find more weight to pull out of the bike...
- make this thing street legal and road worthy as well so I can troubleshoot the bike and get some miles on it before I take it out for a track day or least of all race it.
- The motor... I need to get it running, I think I need to do the second gear fix, it was recommended that I change 5th gear to a bearing style??? I've never seen anything about that and I'm not sure what to do, more research I guess.

My intent/goal for this project is to race at Barber for the vintage festival in October. I believe this to be an achievable goal, except for the fact that because of the size and visibility of that race, there is no riders school on the Friday before and as a new rider in the series I can't make that my first race. Bottom line, I need to have the bike ready to go by the July NJMP race. Still achievable, but I think time is going to fly by and it may not happen. And oh by the way, I'm about to take over as the Brigade S3 (operations officer) for 18th Fires Brigade...

So... any help would be greatly appreciated!
- Anyone have a 78-79 standard seat and tail section they'd be wiling to sell at a significant military discount?
- Anyone have any rear suspension ideas to are period looking but I can still run a 17x4.5" rear wheel with?
- I need some feedback on whether to run the airbox or find a solid velocity stack set-up for the stock carbs.

Any and all help would be greatly appreciated, thanks in advance.

- Adrian

[DiverRay]

Run the stacks that are in the airbox, they will probably give you the best performance. You should have the mount points on the front of the frame for the fairing and oil cooler already. you may be able to use those. Try to find a "modern", but old looking rotors for the brakes. The stock SS ones are close to 10 pounds each!
Get a set of '78 carbs, as well as the pickup assembly, TCI, and cams. The advance for the '78 was the most of any year, and it was the quickest of all the XS1100's built. The tranny is easy, follow along with the mods in the mod section. IF you can have a machine shop do the slight undercut, it would be better. You could probably have the gears Cryo hardened after to keep the wear down. If you are splitting the cases for anything, send me a PM as I have a pdf of notes from '78 for a little work on the inside of the case that will give you a bit more HP.
My guess is you are at Ft.Bragg? I was there in '74/75, 2nd 325th Inf.

[Eveready1100]

Mate, if you cop too much grief over the swingarm pivot mods, here's a photo of the Pitmans Yamaha Superbike circa 1981 as it was raced. That's the predecessor of the Motionlogics chain drive unit that I linked to in another thread., and if you look closely, you'll see that the swingarm pivot has been moved forwards on this bike. I can't see why you can't do this now, if they did it back then???

[Outlaw4shrt]

Run the stacks that are in the airbox, they will probably give you the best performance. You should have the mount points on the front of the frame for the fairing and oil cooler already. you may be able to use those. Try to find a "modern", but old looking rotors for the brakes. The stock SS ones are close to 10 pounds each!
Get a set of '78 carbs, as well as the pickup assembly, TCI, and cams. The advance for the '78 was the most of any year, and it was the quickest of all the XS1100's built. The tranny is easy, follow along with the mods in the mod section. IF you can have a machine shop do the slight undercut, it would be better. You could probably have the gears Cryo hardened after to keep the wear down. If you are splitting the cases for anything, send me a PM as I have a pdf of notes from '78 for a little work on the inside of the case that will give you a bit more HP.
My guess is you are at Ft.Bragg? I was there in '74/75, 2nd 325th Inf.

Hey Paratrooper! Thanks for the response. I was an FSO for Bravo Company 3/504 13 years ago, thank you for your service! Yes, I'm at Bragg again now, hopefully for a few more years.

I may try to run the stock stakes, but I think I'd like some kind of filter on them. I know I've seen some that are similar to the stock stakes with just a metal screen, I might try that. As far as the motor goes, I have an 81' motor with 78 cams. I don't think I can run 78' carbs because I need to use the 81's for the vacuum advance and same goes for the timing. As far as the 2nd gear, and 5th gear, I'm not sure if I'll need to split the cases or not. I need to do a bit more research and see what I'm dealing with.

Mate, if you cop too much grief over the swingarm pivot mods, here's a photo of the Pitmans Yamaha Superbike circa 1981 as it was raced. That's the predecessor of the Motionlogics chain drive unit that I linked to in another thread., and if you look closely, you'll see that the swingarm pivot has been moved forwards on this bike. I can't see why you can't do this now, if they did it back then???

Thanks for that picture! I'll definitely stash that away in the event that it becomes an issue with the technical inspectors.


Got some work done this weekend:
1. Decided that I am going to try and use the 41mm FZR1000 forks that I had on my other bike. Hopefully I can take the cartridge kit out of my 43mm FZ1 forks and have them put in the FZR forks. The issue I have is going to be mounting up dual piston calipers to these forks. I decided I'm going to try and run dual piston brake calipers from an 85 FZ750 with 38mm forks. I don't think the mounting location is the same between the FZ750 and FZR1000 forks so I'll need to figure that out. I went ahead and bought a set of FZ750 forks for cheap off ebay to help with getting the fitment right and in the event I can't get the FZR1000 forks to work.


2. Dug out the motor and some other parts to start getting ready for fitment. I'm starting to get quite a pile of stuff that I need to try and fit together.


3. Rear sets are going to be an issue for me... I'm hoping I can find an OEM set for cheap that I can make work on my bike without paying over $200 for an aftermarket set that I will still have to make work. More to follow.

4. The rear suspension. I'm going to try and get over to Motorcycle Salvation in Bensen, NC this week to try and fit some parts together to make a rear swingarm/wheel combo that meets the guidelines but that is still quality.

That's all for now.

[Mathh]

A shame you have to change the looks of your bike, I think it looks great.
Don't know if you're after 17 or 18" wheels but considering the fact you want to lose a lot of weight you might want to check out the wheels on the first Suzuki slabby's. These wheels are the lightest of all and can compete with even the most modern wheels weight wise. Most classic track bikes overhere are fitted with them and they are getting more and more expensive and harder to get. The 1100 has a 4.5x18 on the back.

Click here for pic

[motoman]

A shame you have to change the looks of your bike, I think it looks great.
Don't know if you're after 17 or 18" wheels but considering the fact you want to lose a lot of weight you might want to check out the wheels on the first Suzuki slabby's. These wheels are the lightest of all and can compete with even the most modern wheels weight wise. Most classic track bikes overhere are fitted with them and they are getting more and more expensive and harder to get. The 1100 has a 4.5x18 on the back.

Click here for pic

......an interesting learning curve Mathh.

[Outlaw4shrt]

A shame you have to change the looks of your bike, I think it looks great.
Don't know if you're after 17 or 18" wheels but considering the fact you want to lose a lot of weight you might want to check out the wheels on the first Suzuki slabby's. These wheels are the lightest of all and can compete with even the most modern wheels weight wise. Most classic track bikes overhere are fitted with them and they are getting more and more expensive and harder to get. The 1100 has a 4.5x18 on the back.

Click here for pic

so I'm definitely trying to run 17" wheels front and rear so I can run quality new rubber like either Dunlop Q3's or their DOT race tire. The look of the bike won't change too much I don't think, sadly, I just have to figure out how to fit older components to the bike. Having said that...

BIG WIN FOR THE HOME TEAM TODAY!!!

I had a little time off of work today and made it over to an Ebay parts retailer near me, Motorcycle Salvation, and the owner Joe is outstanding! He has decades worth of parts and an awesome inventorying system and he let me go through his stuff and build a custom set-up for my bike that I think is going to work out great!

So I was able to fit a 98-04 Suzuki Katana 17x4.5" rear wheel, sprocket carrier, sprocket, cush drives, rear rotor, caliper hanger, and caliper to a 1986 Yamaha FZX700 swingarm and it works great. The swingarm is boxed, but it is steel not aluminum which should make it past the inspectors.

I also picked up a set of 87 FZ750 sumitomo dual piston front calipers that were in good shape. I am going to need to either build or have someone make a set of custom mounting plates for them because the hole spacing is not right for the 41mm FZR1000 forks that I have, but, definitely making progress.

At the end of the day, I picked up great load of stuff, some more odds and ends, today at great prices. Big thanks to Joe and his team for making that possible.

The next step is to start mocking things up again and getting everything to fit/work together before taking it all apart again to weld what I need to and finally get the frame and other parts powdercoated.

[Outlaw4shrt]

A little progress last night. I'm going to have to tear it all down again but I need to get it all together to validate the components and make sure I have everything I need on the frame and it lines up before I powdercoat it. And I want to have the technical inspector look at it again in case he thinks I need to make any more changes.

More to follow in the coming days.

[Outlaw4shrt]

Did some more work on the bike this weekend, and I think I have achieved proof of concept, however, mocking things up has presented quite a few more problems.

1. The exhaust. I guess I really understand the issues now with running standard vs. oil cooled bike exhausts. I think with the oil cooler adapter plate on my bike, it pushes the oil filter cover plate too far down and it bumps into the standard 4 into 1 exhausts. I have a MAC 4 into 1 that I had fitted on the bike before without the filter cover on it and it fit, and now with it on it doesn't... Any 4 into 1 exhausts out there built for the later bikes with oil coolers? I guess I am ok with running the pipes I have now which are 2x 2 into 1. Looking at the old pictures, I believe the XS1100's back in the day were raced like that anyway, but it will make fitting an oil pan much more difficult.

2. The rear suspension. I think I've gone as far as I can with it. I'm going to need some help from someone with experience to line everything up and build the spacers I need for the swingarm itself and the rear axle, or I may just pay the extra money and bring the bike somewhere to have a professional do it.

3. The front brakes. I have a set-up that I think will work, but I'm definitely going to have to bring it to a professional to get the spacer built to line everything up.

4. The rear sets... Frustrating, I'm going to have to come up with something.

At the end of the day though, getting much closer. Starting to look like a superbike a bit.

[Outlaw4shrt]

Getting close now.

https://youtu.be/idsFloL85mU

[Outlaw4shrt]

Changed a few things around and back again, but with some help from the great folks at the XS Southeast Vintage Yamaha Rally this year I've made some great progress.

I got her running today, a ton of things to troubleshoot and plenty of little things to finish, but hopefully i'm riding before the end of the month.

Here's some photos of progress.

[Mathh]

That looks great, I really love the dual fillers on top of the tank.

[Outlaw4shrt]

Thanks, that's the Racefit kit.

[motoman]

Outlaw, in reference to your #5 post, vacuum port for vacuum advance is located on #2 carb same as 80-82 carbs. So yes, you can run the earlier78-79 carbs.