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'90 1127 cafe build

125K views 873 replies 40 participants last post by  rex_saugerty 
#1 ·
hey guys
just got some parts to build a gsxr based café bike.

Its an 1100 frame for sure, but not sure about the engine. the engine numbers are there, but the CC numbers have been ground away for some reason. theres a pic of the numbers, and some of the engine, I know they are common engines and came in loads of different CC variants, but one of you might be able to tell what it is just from looking I guess.

somebody has removed the lower subframe mounts and looks like they have moved the upper ones too, so I will have to make and weld some new frame tabs.

ive got a K1 750 front end to use, with a different upper bearing to fit the OD of the gsxr frame, and the ID of the 750 stem. tried that out before and that's all good, so no issues with putting the front end on.

I haven't got a swingarm yet. ive got access to a bandit 1200 rear wheel and swingarm and might go with that for now.

ive got a MK1 bandit 12 tank for it, its not a direct fit, but looks close enough.....the front mount will need to be extended to tuck under the lip of the frame, and the rear tabs where the side panels pushed into the tank need to be cut off, but id have done that anyway as its just having a café tail and I wanna keep it clean.

any advice about what rear end to use? swingarms and that I mean.....whats a good swap for these that doesn't need too much screwing around.

and if anybody could tell me more about the frame and particularly the engine, id be really grateful.

thanks fellas
 
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#3 ·
Got any pics of the whole bike form the side? I know the 1100 is really tall, and the 750 is alot shorter even just eyeballing it you can tell while it's still in the frame. And that whole numbers thing is sketchy as hell. Someone was just trying to sell it for more just to say its an 1100. only way to tell if its an 1100 from here is to measure the cylinders.

As far as gas tank, bandits tank will look really out of place. Swingers from newer model gsxrs have been swapped alot, just do a search here on the forum and even google. I've not done a swap personally.
 
#8 ·
It's all about the cylinder head for this one. only the 88-89 GSXR 750 motors had the "dot" head. There were also some Katanas that used a variation of it, but odds are that it's the 88-89 750. Other years are tougher to determine.

Edit for clarification: The ******** on Katanas is the same casting and valves as the ******** on the GSXR. However, the Katana uses milder cams and makes less power.
 
#6 ·
the R712 engine code came up as a 750 katana for me when I had a look, I know where the original engine is, but its in bits and not worth messing with really as this one looks a whole lot better. its only a café racer, so doesn't need all the power of the 1127 engine anyways.

the frame is bugging me. the shock mount has been messed with (badly) and I dunno if anything else has.....first time working on a slingshot frame and I dunno what should actually belong where it is and what has been modified. ive got the engine out now, so will go get some new frame pics in a min and hopefully you guys will be able to tell me if this frame is worth bothering with, or replacing. theres a 750 slingshot frame close to me for ÂŁ60 ($100) and its clean and original.

ive got a K1/2/3 gsxr 750/1000 swingarm to go on it, and have tried to mock up the arm with the K1 linkage, but that was nowhere near fitting. I guess I need to get the proper slingshot one. shock is also K1 from my old 750 that I broke for parts a few weeks ago.....same as the entire front end.

could one of you slingshot buffs let me know if all the mounts on the frame look right to you.....ive gotta know that its right before I sit my arse on it. I cant trust somebody elses old welding, especially not on ALU.

i'll get some new pics and post them up next.
 
#9 ·
got my material to build my new subframe today.
ive still got to remove the old top mounts that the frame has had welded on by somebody else in the past, the lowers are already missing so that saves me a bit of time at least.

i'll be getting the swingarm on in the next few days, its a hayabusa I think. looks like a K1-3 750 arm, but doesn't have the gsxr logo on the inside, so guessing hayabusa. I thought it was from a TL1000, but they never came with an arm that looks like the one I have.....its all good anyway, whatever its from, they are all the same size and take the same wheels etc.....

still need to get the rear axle and axle blocks, and work out which shock linkage to use, the slingshot, or the one to match the new swingarm.

once the subframe and seat are on, I can start making the new loom......this bike is just for fun and looking cool on, so wont be having lights as I don't ride at night anyway, so the loom is pretty much just the charging system and starter, easy to make, more of a bugger to hide away as my café tail isn't big enough for everything.

i'll be sorting the frame out tomorrow anyway, so will get more pics as I go along....
in the meantime, if anybody that has done the gsxr/hayabusa swingarm swap into the slingshot frame could tell me which shock linkage I need to use, that would be cool, thanks.
 
#10 ·
the subframe is done now.....took about 8 hours in total of measuring, cutting, welding and so on.....
the welds and edges still need grinding smooth, but that doesn't matter for now.

the front has a brace under the battery, and then a battery box welded to the braces, so the battery is secure and wont move anywhere in its little box.
the back section has the metal tray where the regulator and cdi bolt to, that's all this bike has in terms of electrics as there are no lights going on it at all.

the café seat unit itself sits on the flat mounts, and looks as though it is floating from the side, and the bandit tank has been modified now so it fits perfectly, the tank sits slightly lifted up on its mounts, also looking like its floating a little from the side, so you can see a bit more of the shiny bits underneath everywhere.

I need to get the front end on tomorrow and check my bar clearance, but the bandit tank does have indents, so im sure that it will be fine and not hit anything.

theres still a bit to do yet, but its coming together now.

I don't have an alternator cover or stator yet......so im gonna have to wait till I can afford them to fire the engine, which is confirmed as a 750 katana engine now

everything is different colours at the moment, and I don't have the money for the paint job yet, so will just have to prime the seat and tank for now and leave the wheels odd colours (one gold and one orange)
when I do have the cash, the subframe will be red, main frame gloss black, wheels gloss black, and the tank/seat will be plum crazy purple (like the old dodge muscle cars, but with some metal flake in the clear)

its just gotta look cool and sound good.....not go too fast or be leaned over at 64 degrees like a motogp bike.....its just on old looking café style bike, made for fun.
 

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#11 ·
You have a pic with the tank on? Just knowing those bikes i would suggest making the tail more level and less kicked up. IMO I think it'll flow better.
 
#12 ·
I don't have a pic with the tank too just yet, the seat isn't bolted down yet so couldn't have them both on at the same time

honestly.....I don't like the kick either.....I wanted it flat but my friend that did the welding said try it with the kick. i'll be able to easily adjust it back to flat though.

i'll get him to fix that tomorrow and get everything bolted down proper with a tank and seat pic.
 
#16 ·
ive just tried the tank and seat on together, and it does look better than in the last pics, with the seat set in the proper position against the tank.

the tank has decent clearance with the yokes......but, the bloody steering stops on the yokes have nothing to stop against on the frame.....im new to these slingshot frames, but guessing somebody has cut off the original steering stops??
looks like i'll have to just make them on the bottom yoke and set them at the proper angle to stop against the frame.

the good news is that no matter what angle I have the steering turned at, there is still enough clearance for the clip ons, and nothing bangs into the tank or leaves too little room for my hands, so that's worked out great.

the gap under the seat and tank in the pics, is how its gonna be.....obviously there is still a lot of grinding to do on the subframe to make it look nice and then it needs powder coating, but you get the idea of how its gonna look.
 

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#17 ·
ive mocked up a few things now just to see how it will look a bit better.

I do have the front wheel and discs/calipers, but didn't bother putting them on yet.....all I need now to get the mock up stage done, is a stator and its cover, and the tyres.

the slingshot shock linkage is on its way, should be here by Wednesday/Thursday, and then I can make the new shock mount, which will be adjustable for position, so I can have whatever swingarm on the bike and not need to make a new mount.

I think its looking pretty good now.....the seat does look nicer with the tank and everything on it, but not sure of the angle still. anybody like it as it is, or think it really needs to be more flat?

with the bike as it was in the pic, its still light enough for me to pick the whole thing up with ease, and theres not much more other than the engine and tyres to go on it.....so it should be pretty damn light when its done.

what do you guys think? pretty, ugly, or whatever??
 

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#18 ·
Seat height looks just right to me. I usually base that on how it sits relative to the top of the tank, and that one is right on the money.
 
#19 ·
awesome. with the tank off, it looked a little high, but with everything on in mock up, it does look a lot better.

im hoping to get the stator and its cover this week, and get started on the engine.
honestly, its a total unknown for now.....it turns over by hand, but that's all I know about it.
ive got standard coils for it, but have had good success with stick coils on some of my other bikes.....they are easy to modify to work on any engine, and only take ten mins to do.
the standard coils have no caps on, and just the new caps are more expensive than swapping to modern stick coils.....id just need to get some waterproofing on the wires, because they are a lot more exposed in the way they plug in, but that's easy too.

does anybody know where to get rearsets for the slingshot? ive literally not been able to find any in the uk, so was just going to make my own.

also, the swingarm in the pics needs to be swapped out for a new one.....theres a massive ding where the right footrest would be, and its missing its bushes at the pivot.
I can get a replacement complete with everything for less than just the bushes, and for ÂŁ30 I cant moan about it.
 
#20 ·
got a little more work done today, no more pics as you wouldn't really be able to tell any difference.....but found a few things that need modifying to work right.

first, the top yoke ignition mount hits the frame on right turns.....no problem as the bracket was coming off anyway and the top yoke smoothing off and repainting. the ignition will be hidden somewhere with a push button starter and kill switch hidden on the side somewhere.


second, the seat.
with it in the position it was in, in the pics......there is just enough room for my arse when sat upright.....so I think it needs moving back a bit, but in doing so.....I expose the tank mounts, not really a problem and doesn't look too bad, but maybe it'd bug me after a while. I can also see the battery in the gap too which would definitely bug me....
so I guess the solution is to make a metal tray under the seat that will reinforce the fibreglass, and move the tail into the right position and cover the battery/tank mounts better too.

also, does anybody know of any good slingshot rearsets?

im finally getting hold of some of the missing bits, and will be making the shock mount tomorrow.....the wheels will be going for powder coat with the subframe sometime in the next week or so, then the tyres can go on the once and stay on.

the frame has some scratches that are deep, but it can easily be cleaned up at a cost of zero......just my time, which I have plenty of anyway.


anybody got any suggestions or comments?
I think its coming along nicely now and if I do get the parts I need soon enough, the bike will be done in the next few weeks......ready for setting up the suspension and geometry and tuning the engine properly.
 
#22 ·
i made a mock up shock mount the other day, just for test fitting of the swingarm and everything.....no pics as its already being used as the template to mill out the real one out of alu.

last things to do on the fab/modifying side now are to fix the steering lock stops so they actually do their job (they are too low at the mo and don't even touch the frame at all)
make a new front tank mount, which is easy enough.
and maybe machine out some new dog bones.....ive cut down some strong alu ones that I had on an old frame that was lying around, but might just make new ones that are a bit thicker.

ive got the left side engine cover on order.....so used to the newer engines that ive been calling it the alternator cover all this time, when its actually the starter gear cover on these older engines. when that arrives and the shock mount is back here (Monday/Tuesday) I can get the engine back in the frame and start the more fun work.....making the wiring loom and getting the engine running.

going to strip the carbs later today, which are bandit 1200 carbs on my 750 katana engine (R712 comes back to the first gen '88- katana....same as the newer one, but black paint on my older one, and silver on the newer ones)
I have no idea of the condition of the engine/carbs so far.....the engine is outside under a few bike covers, with all the ports plugged up and tyres and other stuff on top of it.....ive really had no need to even look at it so far, so just haven't bothered yet.
i'll get pics of the carbs while they are apart.

my subframe is getting powder coated soon, along with the wheels.....but the tank and seat will have to wait for their paint for now till I can afford to do them.
 
#23 ·
You and your build remind me a lot of me and mine. I've got a 1992 GSXR 750 I'm building under a shed roof kinda thing. Found the bike under a second floor deck getting rained on and being neglected. Frame had been modified at the subframe as well. Hell I even have a fiberglass cafe tail I was going to put on it. Its eerie how much our builds have in common and I know exactly how challenging it can be for you to build it in these conditions so I gotta give you a lot of respect for doing it. Its coming together real nice and I'm glad you haven't given up on this frame. It was a champion in its day and doesn't deserve to be abandoned because of the awful ways others have mistreated it.
 
#24 ·
My shock mount will be done tomorrow.....its machined from a block of alu to the right thickness for the extended length that the shock needs to be away from the frame.

I got this project as a pile of parts that had been sat for years
The slingshot / bandit frames are really pretty and I've wanted one for years now.
The bandit tank even looks right on the slingshot frame too.

Here in the UK, good slingshot streetfighters / cafés can sell for about £3000..... This should only owe me £1000 when its done. But I will be keeping this one for myself.....its too cool and endlessly customisable.

I'm thinking of making my own alu tail.....ill use these dimensions from the fibreglass one, but make it kinda like aircraft parts are made....ribs and sheet alu, riveted together.
I cant weld, and cant afford alu welding to be done, so that's the best option and still plenty strong.
 
#25 ·
I really like the idea of the riveted tail!... If you know a good air brush artist they could do up a paint job on the tank with air brushed rivets to match.

Either way glad to hear your making progress on the bike!
 
#26 ·
I've wanted to do a riveted part for a while now.
At first, I wanted the tank and tail to be bare metal, cleared over, but the only metal tails I have been able to find, are indian things and I couldn't do that to a slingshot gsxr.

Alu welding isn't so common I'm England for some reason, and when I've had it done, its been really ugly, unlike the great alu welds I've seen on American bikes, so the riveting idea seems like the best way to hand make my own tail without the expense and hassle of welding.
If I can get the tank to be really clean metal and metal finish it so it is presentable, then id love to just have a bare metal finish on the body.

I'll keep the fibreglass one on for now, but only for mock up....the final tail will definitely be a riveted alu one made by myself.
 
#27 ·
ive got the new swingarm on the bike now, all lined up and centred perfectly, just still waiting on the shock mount to be finished

the swingarm was super easy actually.....all ive done to fit this one was knock out a roller bearing, take out the central sleeve, put another in that's 20mm and shorter than the original, and put my end spacers in.....but mine were from a slabside gsxr swingarm, and had flanges on the ends.....just so happens, that without the chain rubber and side spacer on the new swingarm, and the new spacers slotted into the old gsxr ones.....it fits dead centre of the frame with no gap at all.
so even though I had different bushes to the ones used in the how to guide here on the site, this worked out even better and even easier.

theres loads of room for the shock, and it would even bolt in without hitting without the need for the shock mount to be spaced out.



that's all for now, but there will be more progress in the next few days when I get some more parts and get the engine back in.
 
#28 ·
finally some progress worthy of a post.....with pics

I got the temporary shock mount back, its ugly obviously, so just ignore that.....its just for mock up and was the template for the one that's being machined.
everything lines up beautifully, there's plenty of clearance between the shock and swingarm etc...

I still need to get proper bolts for the linkage and shock, but I just wanted to see some progress after being bored with it for a week or 2 now.

the forks are sat way down in the yokes, by accident if im honest, its a bitch lifting everything to put the front end on with the back already in, and that's kinda just where it naturally sat......but, I kinda dig it.
if anything, I think the front is sat a little higher than the back....like, less than an inch, but im sure I see something there.
there is still loads of bar clearance though like they are.

also put the seat back on just for the pics, so again, ignore the subframe.....its steel, and hasn't been coated yet, cant afford it just yet.....so its a mess with surface rust for now, but will be dealt with soon.

last thing to mention, I also got the rocker cover off the engine, and my cam codes do indeed come back to early 750 katana......ah well. i'll have to change the page title now we know its not an 1127.

anyway, the pics.....








 
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