1127 Dragbike Build

Ok, so how did this purchase happen? Some of you know I have a 1990 GSXR 750 build going on. As part of building this bike, my daily routine is searching eBay for parts (I have a long list of key words I use), checking cmsnl.com, Facebook Marketplace, and Craigslist. When I was searching Marketplace, I saw a listing for this bike with the title"1998 Suzuki" which was just listed. The bike appeared all original with the exception of an aftermarket exhaust. The price they were asking was definitely below current market rate (which is a bit insane the last few years). I immediately thought a few things: A) this will not be here long, B) this would be a much better platform to run than my 90 750 at the drag strip, C) I have a TON of NOS/aftermarket parts sitting idle on my shelf that I can use on this thing. I immediately called the guy, told him I'm on my way with cash in hand and will buy it assuming there are no unforeseen major issues with it (my wife was not so thrilled by the news). When I got there, I looked everything over. This was in a similar state as my 90 750. The bike was pretty mint until the owner dropped it on the right hand side. Such a shame. Also, the tank had a few dents and the clear coat was coming off. Outside of that, is was as expected. I fired it up and it became clear it was in need of some serious maintenance. Once warm, it would not idle. I took it for a ride and hammered it multiple times in the 1-2 shift to see if it would pop out. Transmission had no issues and it ran well under WOT. I was surprised by how much more power it had over the 750. It even scared me initially. Drove it back, handed him the cash and got ready to put it on the trailer. I notice then that it had an intermittent short more than likely on the ignition switch. No biggie but is was something that I needed to sort out.

Got the bike home and immediately started pulling it apart. Fortunately, I didn't find too many surprises with a few exceptions:

Swing arm had the common "exhaust wear" issue. Irritating, but I sourced another off eBay. I missed this. I also missed the Vance & Hines header had 2 small dents. I did check for this but it was impossible to see them until you took the header off. I had no intention of using it though. The first thing I did when I got home was call Ripple Rock Racers/Hindle and ordered an exhaust. I can't overstate how nice it is to simply pick up the phone and order a new exhaust (it took me numerous exhausts and a few years to sort out my exhaust situation on my 90 750). Arrived quick and I'm pretty happy with it, especially how the "Y" connections are horizontal and not vertical like everything else. This should give me and extra 1.5" of ground clearance which matters when you're trying to get the bike as low as possible:



I then turned my focus on the wheels & tires. I cleaned my original 750 wheels, swapped out the bearings, cush drive, front tire, and rotors with new parts (which I already had), ordered/mounted a new Shinko Hook Up 190 tire for the rear.

I ordered a lot of new stuff which is currently coming in. Here's current state:

Still have quite a bit of work to do but I should have most of it complete in a week.

My swing arm came in but it was a 89 1100 arm and was shorter (anyone need one?). Then I remembered a welder that I used in the past and brought it down to see what he could do. $50 later the problem was solved. I should have done this from the beginning:


When going through the fuel system, I found 2 of the carb boots had leaks to the open air (between the boot and the head). It was a bit of a challenge getting all them off but replaced all the O-rings. Then I turned my attention to the carbs. Got a new jet kit, rebuild kit, and some stuff off Ron Ayers. When I was pulling them, I found the air cleaner (presumably the original one) was PACKED with seeds and completely black. And I mean packed. I have no idea how any air got through it. Also, inside the airbox, was a coating of fine sand/mud. I found some in the carb bowls as well. A bit concerning. This mud I found throughout the bike in weird places. I'm guessing the owner lived off of a dirt road that the bike traveled to some extent. Anyhow, rebuilt the carbs, got a new K&N filter, and gave it all a solid cleaning:

One issue I came against was one of the carb top caps had the barb broken off. I sourced one off eBay but it ended up being different. I went to McMaster Carr and got part #'s 1658T12, 7605A5. I drilled out the barb with a 3/16 drill. Then I spun down the O.D. of the aluminum tubing to match the hole I drilled using a pedestal grinder. I left extra hanging out the bottom side so that I could file it flush with the sealing surface. A little epoxy and walla - its fixed:

The crown jewel came in today - NOS gas tank. Pretty stoked! At least I will not have to deal with a rusty tank on this build. Also ordered a full body kit from Airtech that will at some point down the road get painted to match.

Mounted up my exhaust. If you have a gen2 and you're looking to toss the stock exhaust mount, Yoshimura #200BG111820 is a direct bolt in swap without mods. I run one with both bikes (1100 & 750).

Parts are slowly trickling in. When I pushed on the rear subframe to test the current state of the shock, it was a pogo stick. Also, it was pretty obvious the leverage ratio wasn't great as it transitioned from nothing to a rock rather abruptly (before the shock bottomed out). So, I bought an "SRS" link from ACC Billet Engineering (great to work with btw - super responsive and quick shipping) to fix the ratio and a new Penske drag shock. The Penske was setup for the SRS and with 2 springs - one for stock wheelbase and one for +8" over. Next I needed some lowering links. The only option I could find was Soupy's Performance. The 1100 links they sell are set so you can lower and raise the ride height. Knowing the SRS will raise the rear by about an inch, I wanted to have more drop adjustability. I bought a set for a 1990 GSXR 750 which is a little longer and offers more drop potential (I need to set them to the same length). With that sorted, I need to get it installed and setup:

When researching the motor, I found several people who recommend buying billet 2nd & 5th gears on the output shaft. In a stroke of luck, I contacted Robinson Industries Inc who had some in stock. He cut me a deal and gave me a free 2nd gear drive which I was super stoked about! Output gears are undercut and work with stock gears too.

Running the bike this year wasn't in the cards. I sent out my forks to have them shortened and setup for drag racing to someone who assured me it was going to take 3 days to turn around. 3 weeks later he hadn't even opened the box and told me I was 3rd in line. When I asked for them back I was told he couldn't ship them for a week cause he was out of town. I really don't like it when vendors lie about turn around time to get the work in the door thinking at that point you'll just deal with whatever they give you. I had them shipped back and sent them to Traxxion to get it done. Also, the Soupy's Performance links hit the swingarm. I made the mistake of throwing the stock ones out so there was no going back. These things combined put me out to next season which isn't that big of a deal really all things considered.

One of the things I want to do with the bike is bracket race. In bracket racing, consistency is the key. With this in mind, I decided to buy an air shifter. I wanted to get the most reliable system available so I picked up the Schnitz Racing kit. It comes with a shift module that enables an auto shift function which simplifies things. I also picked up an MPS co2 tank so I wouldn't need an air compressor setup. Might take me a while to get it sorted out but should be a pretty bomber setup when done.

Over the last few months I've been going back and forth about what approach I'm going to take with the motor and when I'm going to build it. Do I do all motor, turbo, or nitrous setup? All options are pretty expensive when you map out the costs of doing it right and add it all up. Initially, I was thinking turbo but when you really dig into it, it's going to take a lot of trial and error to get everything figured out which I'm not crazy about. It's also the most expensive but also allows for the most power in the end. A stout all motor build will have the least amount of power and a lot of maintenance so kinda crossed that option off the list. Right now I'm thinking of building a 100hp nitrous shot motor. Thinking is I can run it as all motor most of the time and use the NOS when the track conditions are right. This will make it a 8 second bike and a 9.4ish bike on motor. Still unsure of when I'm going to build it but time will tell.

A bit more progress. One of the problems to solve for this build was how I was going to lengthen the wheelbase. No one makes bolt on extensions for this thing any more and nothing used was available. I did contact DME and they could fab a swim arm for it but it would use a gen1 Hayabusa rear wheel. The problem this causes is the chain line is different by 10mm and would need get a custom sprocket to fix it. Also, I would need to buy a hayabusa rear wheel complete and a rear brake hanger and caliper. Seeing as I already have new sprockets, a rebuilt GSXR wheel and caliper, I decided to go the extension route. So I modeled up some 8" swing arm extensions in CAD and sent them out to Protolabs to machine out of 7075. As a former machinist, it really pains me to pay someone to make me parts but I no longer have access to CNC. $750 later I got parts. Still need to do some post machining (drill & tap some holes) and make backing plates but we're getting there. I also made some adjustable lowering links. I do have access to some crude machines (no DRO) so this will work for now.

The lowering links enable me to throw the rear wheel back in and pull the stock 1127 front end. I decided to convert over to a 1990 gsxr750 front end to save weight. I found a perfect set of forks for $140 off eBay so had them fully rebuilt and "cut" to 2" of travel. One thing I noticed as I pulled this bike apart is just how stupid heavy everything is. This bike will be a lot lighter. I had a hard time buying a good front headlight assembly and fairing stay. After getting in some junk, I found CMSNL had a new faring stay for $140 so went that route plus found an NOS headlight bucket to build from. A new Shindy damper, Woodcraft clipons, CRG levers round it out. Having today off of work, I should have it all installed (minus the extensions) by the end of the day.

My initial plan for the build was to tackle the motor at the end of the 2023 season. I decided, however, to take the build on now. Where did I end up approach wise? Here are the details:

Fuel: 40mm Mikuni carbs with oversized 90-92 750 intakes (USA model)
Cylinder Head: Rocker head (non-shim), ported, decked, oversized Ferrea 30/26 stainless valves, APE: titanium retainers, heavy duty springs, seals, keepers, valve guides
Valvetrain: .400" lift Web cams, welded rockers
Block: Aftermarket big block, 1340 set to 12:1 to be nitrous friendly, oversized sleeves
Crank: APE magnafluxed, lighted, balanced, and straightened
Rods: Carrillo H beams
Transmission: Robinson billet 2nd & 5th output gears, 2nd input gear. Rest of the gears APE undercut
Clutch: MRE multistage lockup, Warp Speed Racing quick access cover
Misc: APE top end oiler, APE adjustable cam sprockets with heavy duty cam chain, APE cylinder & main studs with nuts
Power adder: Nitrous and controller system TBD

What kicked all of this off was finding a used aftermarket big block on eBay. These things are super hard to come by and pretty much unobtainium. Can you believe I got it for $400? I decided then to buy spares of everything and have them sent out for the build. I didn't want to be at the mercy of supply chain and people turn around times with a disabled motor. With that, scored a used crank and sent both out to APE:

I got a call from Jay at APE and much to my surprise, the crank passed magnaflux. The 1127 cranks are super crack prone and this was an eBay crank on the cheap. Jay said at least 30% of these cranks come up cracked. Something to keep in mind if you're going to build an 1127. Block checked out but needed everything - resurfacing, new sleeves, bore/hone, etc. I also ordered the Carrillo's which he was able to located in stock. Currently all of this in in process.

I purchased an eBay head (86 1100). Why do so many people try to sell heads without cam caps? Super annoying. It took me 3 months and multiple purchases to find a good core. There was a lot to consider approach wise with the head. Epoxy or no epoxy? I ended up going the no epoxy route as everyone I spoke to said it would eventually fall out over time. Epoxy will make more horsepower by raising the port floor, but didn't want to take the long term reliability risk. Valve size is another consideration. I decided not to opt for 31mm intake valves and went with the 30/26 route. Knowing I'm going with nitrous, I figured keeping it reliable for the rest of the build might be a good path plus I went with no epoxy anyways. Sent the rockers out to APE for re-weld and the head to Cooper Performance for port work. I put in a lot of work researching who knows how to port these heads. Carpenter wouldn't take it on. There was one name that consistently came up from the people who used to build these things back in the day: Cooper Performance. All said and done I can't recommend him enough. He was super responsive and turned around the head in 2 weeks! If you need his contact info, he has a page on Facebook.



As for the rest of the motor, pulled some cams I had in a katana motor and sent them to APE. Bought a spare transmission, new bearings, and sent it out to APE with the billet gears for undercutting. Purchased a spare set of cases and sent them in to Cooper performance to have the cases bored and some of the oil galleries plugged. Pretty much everything that needs to be ordered and machined is in progress.

It took some serious research but I was able to locate an APE top end oiler and heavy duty cam chain. Both have been discontinued for a number of years. The MRE multistage lockup came in. Should be "fun" to setup and dial in.

My bodywork also came in, along with the decals. Needs to be mounted. The quality of this body is much better then the one I received for my 750 so that's a plus.

Now I just to carve out some time to get some of this assembled and sorted out.