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Building a frankenstein

176 Views 4 Replies 3 Participants Last post by  TwistedMister
Hello everyone, this is my first post here but I'm sure there will be a few.

Just to make a quick Introduction I'm 23 and been riding since 19, my first bike was a 1982 GS650GL and I bought it without realizing it was a project, now I know that bike inside and out and it's in the process of getting mechanically restored and bored out to 740cc, this is before I realized it was a waste of time to bore it out as there are plenty of way faster bikes out there. I also have a 1976 KZ750 that it a hardtail bobber, bought that one knowing it was a project and got it going in a night's work.

Now, onto my dream bike, ever since I seen a 1986 GSXR and learned the history it has been my favorite bike ever since, there also my favorite looking GSXR of all because the tank is not a flat top, for some reason the first generation tank shape is by far my favorite, aswell as the rest of the bike.

Anyways, I finally was able to get my hands on one....project that was in bins, but that's how we do it to save money and take more appreciation.

Thebike i got is a 1986 GSXR 750, I got everything except a tank, seat, carbs, exhaust, and coils for the bike, and it came with two sets of forks and engines, for $250 USD, with a title!

And now there is a third motor, I wasn't planning on it but I got offered a 1991 750 motor for $20, so I couldn't refuse.

So now I have 3 motors, an 1127 that seems to be from a katana and also missing its timing chain, a 1986 750 that had rusty water come out the oil lines when I moved it, with the intake ports matching, and a 1991 750 motor that has low compression on two cylinders and a bad second gear.

I have already bought a tank and seat, aswell as exhaust and carbs, and coils will be no issue, I already have a set of plastics lined up to be bought aswell.

The build plan atleast for the frame and motor is going to be a 1986 750 frame, a 1991 750 motor as its the last oil cooled 750 and the most powerful, aswell as the seemingly easiest one to rebuild as far as condition, and it is going to be fueled by GSXR 750 slingshot carbs.

So I already know there's a couple things I need to cover, I understand an airbox will not be an option, and I also know that the slingshot carbs are 36mm while the 91 carbs are 38mm for the 750 motor. I picked the slingshots as they can be used on the 1127 and also got a really good deal on them. I also know I need to use a 91 exhaust as the oil pan shapes are different on the other motors, which is fine as I have picked up a Yoshimura header pipe for the correct motor, a mid pipe and muffler configuration will be figured out no problem.

So, ofcourse let me know if you see any issues or have any questions to help me out or just curiosity about my configuration.

I do have a bit of a dilemma with the parts I received with the bike, I said it came with two front ends, it also came with a couple other things that were not with the original bike. I actually have a bunch of watercooled 1100 parts that came with the bike that will not be used more than likely.

So, I have an original front end that would need to be completely gone through and a watercooled 1100 front end that will not work without changing the tabs on the neck of the frame to stop them from breaking my hands, and it's also too tall of forks to be used.

I'm thinking of using a set of 1991 or 92 750 forks as they are a straight swap and also much better than the 86 forks.

I also have a watercooled 1100 swingarm but my buddy said it'd be a good one to use and the roads here aren't the best so I'll be fine with that.

Also I have watercooled wheels which will be fine, now they don't look as nice as the 86 wheels but I can deal with it, for now.

The rear shock is also from a watercooled 1100, so will I have to use it because of the swingarm or should it be changed?

Also, will I have to use the same wheel that came with whatever front end I use for the brake calipers to align properly with the disc's or is it easy enough to make whatever configuration I use work?

Sorry for the lengthy post, it's my second time building a bike from the ground up but my first time building a Frankenstein.

The goal is to have the best configuration for my frame without doing any serious modifying, I want this bike to be rideable on the street no problem and also do well enough in the turns, but not track oriented.

Also, the reason I'm not using the 1127 motor is because I rode my friends ZX7 with a ZX9 motor in it and couldn't even open up the throttle, it was an amazing feeling the bike gave but I'm obviously not ready for that much power yet. The plan with the 1127 is to rebuild it while I'm using the 750, and when I put the 1127 in the bike I will modify the 750 as much as i can basically, and then do the same with the 1127, it'll be a cycle lol.
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Welcome to the forum.
There's lots of support here.
Post some pictures of your project, when you get a chance.
Thanks for sharing, I look forward to your progress.

There's a couple of Parts Interchange stickys at the top of this section...have a look through there about different combinations.
Try the Search function at the top of page as well...there is decades of Oiler info archived here.
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I'll post pictures hopefully In a week, my foot is messed up right now and I'm stuck in bed.

I looked through the tagged posts, and it's all great info but the 86 Frame isn't in the same tagged post as the slingshots and early 90s gsxrs, I think it's basically the same for the front end and hopefully the swingarm so I should be good.

I think I'm going to use the latest year 750 forks that are a straight swap, or do a later year fork and use the right steering stems so I can make it work.

And for the swingarm it'll either be a 750 swingarm from a later year or an 1100 swingarm, I figure it's not bad to have a longer one as it'll help with stability and I don't think I'm dragging knees anytime soon, the roads here aren't the best anyways.

As for the rest, that'll be figured out, I definitely want a great set of brakes both front and rear, and ofcourse I want my Powerplant configuration to be smooth, since I'm gonna have to use pods a bit of the smoothness will be taken away but eventually these motors I have will be modified and need pods to really pull out the power.

The rest will be fine as this is most of the bike already planned out.

I just have one question for now, since I'm using a 86 frame and tank and 88 carbs, the only way I'd be able to run an airbox is if I use the 86 airbox with 88 rubbers on the intake side, right? But I have been told that the original airbox is rather restrictive so it wouldn't be a good idea anyways for my plans.

Here's two pictures, these are the two colourways I will have to decide, blue is always gonna be an amazing look on the bike but the red is alot less common and I contemplate if I like it more, and the skoal colourway uses my favorite color and is alot less common to be seen, im not sure which out of the two looks ill do, probably the original look, it'll keep it unique. In a world full of blue gsxrs and some red, this will be a pleasant site.

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