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Twin Engine GSXR Land Speed Racer

55731 Views 337 Replies 83 Participants Last post by  Beairsto Racing
Hi everyone,
This my first post. I was slacking off and surfing the net hoping to find race parts for early GSXR's and ended up on this site and then was surprised to see a recent thread on one of my race bikes. I just enjoyed my 8th year competing at the Bonneville Salt Flats, I've had some success with very large displacement Hayabusa's. I still own my first race bike, a 1986 GSXR 1100 built as a period endurance racer.

One of my mentors, Larry Forstall built my twin engine GSXR back in the early 90's. Larry built it to run in the "naked" classes without any bodywork. Other than a couple of shake down passes which were aborted due to vision problems and salt conditions, the bike has never run. The Double sat for over a decade in Pennsylvania. I met Larry in 2002, the year that I got inducted into the Bonneville 200 MPH Club and he mentioned having a twin engine GSXR in storage. I was after Larry for several years to either sell it to me or let me fix it up and race it. Bonneville has such a rich history of multi-engine vehicles, I thought the Double was very cool. I was teased with pictures at first but Larry finally agreed to sell it to me and I had it shipped up to Alberta, Canada. I will always run it as a "Beairsto & Forstall" entry. Larry is an innovator and I'm proud to own a piece of his work.

The Double uses a pair of 1986 GSXR 1100 engines, they are now 1255cc with Cosworth pistons, ported heads, Carrillo rods, Falicon cranks, Megacycle cams, 40mm flat slide Mikuni's, all the good stuff that was available at the time. Older technology for sure but horsepower is horsepower. The engines are coupled together, both transmissions are engaged.

I work overseas in the middle east and Africa, I'm not home much and it was hard trying to get 3 other race bikes ready for Bonneville. As anyone who has run at Bonneville knows, corrosion is a bitch. It doesn't seem to matter how much you clean up afterwards, it ruins everything. Having sat for so long, the bike needed some attention. I also wanted to be able to run the bike with bodywork and decided that an early GSXR competition fairing was the right choice. We replaced the wiring harness, spark plug wires, cleaned the carbs and got the front engine running fairly quickly. The rear engine gave us a little more grief but we sorted through the electrical gremlins. A seized rear custom clutch slave cylinder almost kept the bike at home, we fixed that the night before we left.

I had never driven the bike until I let the clutch out for the first time on the salt. Its very stable at speed but it is a bit of a stretch even laid out over it and the gear shift pattern is backwards.
The front engine is started using a battery cart, with the bike on a stand, I shift into 1st gear, rev it up a little and drop the clutch. The rear engine fires up and the bike gets alot of attention. I put it back into neutral, the stand is removed and I wait for the starter to give me the ok to run on the course.

I did a couple of passes on the short course to get familiar with the bike but we soon discovered a weak link in the engine's coupler. I knew with the weak idler gear that I would only be able to make a few runs. My top speed was 203mph @ only 7000rpm, the bike has alot of potential in it. I like it because its different, my Hayabusa disappears in a sea of other 'Busas at Bonneville. On my last run, we actually broke the coupler's idler gear and the loose chain caused a bit of damage but nothing that can't be repaired. There's nothing like running 200 mph and hearing bad crunchy noises coming from the coupler.

I hope to be able to run it again this year at Bonneville or El Mirage, work permitting. The bike is in a shop right now getting the coupler modified. I also need to improve the rear suspension and add some ballast for traction. It just spins the tire hopelessly at anything over 3/4 throttle. Over the winter I'd like to throw some more power at it and upgrade the 1255's, its a shame they stopped making the big blocks. We are entertaining the idea of adding fuel injection as well.

Well I should get back to work.



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I may have missed something but it seems the bikes setup is running with clutches linked on both motors and I am guessing both shifters linked toghter as well. If that is the case it doesnt matter if the motors are timed together seeing as its not coming from the engine output shaft.
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