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Motor went BOOM yesterday, its 7/11 or 1100 time

30K views 323 replies 19 participants last post by  Gixxerider86 
#1 ·
thats right, not even 4k miles on a full motor rebuild and it took a dump during a fly-by vid I was recording yesterday. My guess is it started running lean (I had to switch from "on" to "reserve") and I ran it too hard for too long while too lean. Ill investigate later. as for now, Im considering doing what I should've done from the start and thats dropping in a bigger motor.

I think I've seen a master thread somewhere on here where every member who's attempted this listed all their successful configurations, Im talking oil cooler options, 1052 1127 and 1157 (b-12) engines in a 1st gen, header options, etc, but I couldn't find it. anyone know what I'm talking about, if such a thread exists? I thought I've seen it? Ive been reading that ill be able to still perform valve adjustments with the motor still bolted in the frame on any motor swap. I wonder if Ill be able to run air filters, the dual pod for the slingshots on my 750 are already a little smooshed from squeezing into the frame, any of these motors will be taller and I will still be running slingshot carbs as I have a nice set from an 1127. Will all the existing wiring and electrics work? I see a bunch of 7/11 conversions for 2nd and 3rd gen 750s but not so many on 1st gens.

My other option would be to locate a cheap 1100 and transfer all the good stuff from my 750 onto it: dyna coils, plastics, tank, lights, brakes, pretty much everything but the motor. maybe even front forks too, since they are rebuilt, and wheels/tires. This route will at least take out most of the guess work.

Consider this thread build #2, on a slight budget
 
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#2 ·
hey i love your idea on a 7/11 swap. but i do own a 87 gsxr that i wanted to do that 1052 swap in it to . but i just dont think that first gen gsxr frame cant take the power of a 1052 or any bigger motor. unless you do alot of frame bracing.i would feel safer to put that 1052 in a 2nd gen frame only because it has a little bit of a beefier frame than first gen . just something to think about.
 
#3 ·
That's bad luck . . .
Could be something else - poor fuel supply would make it run poorly first, then burn valves etc if it ran too lean for too long.
GotGixers has a tuned 1216 in his 750 frame ! he's one of quite a few on here I think, I don't know what he's done to the frame - like fit the stronger/longer 1052 swing arm etc - he does have GSXR1000 forks on it, I know that.
 
#4 ·
Maybe I'm asking the obvious here - why did you continue with the high speed flyby if you suspected a lean problem?

I remember from your engine rebuild thread that you had lean issues from the get-go. In those 4k miles, did you get the engine running sweetly/tuned/set-up properly?
 
#5 ·
yes I ended up with slingshot carbs from a katana 750, switched parts over to make them '88-'89 GSXR 750 carbs. got brand new emulsion tubes and needles that are for those carbs and were WAY too rich, ended up running katana 600 needles and tubes which were perfect, for a little while until they started wearing and creating another rich problem. main jets were spot on, perhaps very slightly rich.

as I was doing the flyby it was pulling just fine until I started loosing power quickly, let off the throttle then pulled in the clutch and I immediately knew something went very wrong
 
#6 ·
I've got a very nice 1340 91 1127 I'm parting have a look in the classifieds, for pics and a write up, I'm just starting to part it. It might be up your alley. Can provide you with a complete set of 1127 mounts, carbs( 41mm fcr's) etc etc
Sorry about your bad luck.
All the best
Dave
 
#7 ·
hi mate ,that sux alright , did you hear any horrible noises ? did it actually go boom !! Could it be an electrical fault ? , my 1100 lost all power under full throttle one day and started running on two cylinders , felt like I hit a brick wall, it turned out to be the cdi unit .The first gen 1100 frames flex a bit and are stronger than the first gen 750 frames so I would be thinking you would need to gusset the frame for sure , thats one of the reasons I decided to use a 2cnd gen 750 frame for a bigger lump as it is stronger .If you are going to transfer all the bits over to a first gen 1100 and all your parts are original ,there are some differences .Off the top of my head ,your forks are shorter , the upper fairing is a bit narrower (it would fit if you use your 750 headlight/fairing bracket ) , the mids have the upper mount in a different place but otherwise the same ,all the rest of your fairings are the same . the swing arm is shorter ,your headers most likely would be too short to clear the sump , your wheels look the same but are not as wide, the brake discs are smaller and not full floating .The cdi unit will be programmed differently I would be thinking . there are other differences too . there is a sticky at the top of the forum for known swaps , it might be what you saw . I hope it all turns out well what ever you decide to do , take it easy brother .
 
#8 ·
this is great info right here, thanks a ton! :punk as I spotted a nice 1st-gen 1100 semi-project. everything is there as well as a rebuilt 1052 motor. I might consider transferring over all my plastics as well as the headlight and bracket, he has slingshot plastics that are primed (no paint) but I dont know if they will fit. Im going to utilize the 1100 swingarm, Im thinking maybe running the 750 wheels with the 1100 rotors and spacers, I wonder if the rear wheel will fit that way? as its a longer swingarm I will need to add links to my chain (which I have) or get a new one. Or just use whatever's on there wheel and sprocket/chain-wise and get new tires, definitely transferring over my rebuilt calipers and SS lines. The only electronic part ill be switching (other than possibly the headlight/taillight) over are those coils, and last I talked to dynatek, IIRC, they said the coils will work on 750s AND 1100s? I really need to revert back to that sticky

lots of ideas and lots of questions, but I need to look at the bike first and see if its any good, then get it. all of this is just a game plan
 
#9 · (Edited)
Hey G86,

Your thread title says your motor went boom and you've said it took a dump, however the only symptom you've described is it quickly started losing power.

Did it make any mechanical knocking noises? Are there any holes where any internals tried to get out? Did it idle after you came to a stop? Have you removed the sump to check for debris? Did the oil light come on? Does it turn over by hand with the plugs out?

Have you thought about pulling the engine to check what's right and what's wrong? Maybe if it was leading to a seize condition you could get away with a 2nd hand barrel and new pistons. My point is - it could be a cheaper option than the 7/11 or 1st gen 1100 option
 
#10 ·
hah, you're absolutely right, sorry about that everyone. I was doing a flyby video and was going around 150 when I started losing power quickly, after switching the fuel tap to reserve so I knew it wasn't running out of gas. I pulled the clutch in and the motor locked, bumped the clutch a few times (which I probably shouldn't have done) to free it up as I was slowing down. I looked back and there was a bunch of blue-ish smoke from burnt oil where I passed, I started it back up and sure enough loud clanking, metal-to-metal noises coming from the motor, I shut it off immediately. I didnt give it a thorough look-over, but there wasnt any huge oil leak and from a quick look around I didnt see any holes punched through the crankcase. It sounds like something went bad inside one of the cylinders but I could be wrong. I also noticed some oil seepage around one of the head studs that wasnt there before, and the bike does not want to shift into nuetral and was a little tough shifting down to first after coming to a stop.

My logic is that Im looking at least at getting another wiseco piston and rings, a new sleeve, head and base gaskets, new valves and probably some machine work done. Thats already around $500, thats not if anything else got damaged in the process. I dont want to tear down this motor again, not yet, and I was already considering something bigger. One of the mistakes I made was getting high compression on this bike, not that I had any problems (I didnt) but I do wonder if there was any detonation involved. Around here I can find a complete, not-so-complete 1st gen 1100 with a good motor for $700, gonna go look at it today. Im sure I can get a hold of a known good running 1052 or 1127 for that same amount, thats just for a motor let alone a bike. I know I could sell my '86 750 as a parts bike and get my money back, or throw another motor in there and sell it whole
 
#11 · (Edited)
I COMPLETELY forgot that I still have my stock pistons and rings that are in very good shape! I honestly had no business tearing down the motor in the first place, maybe I will just rebuild this motor. Ill need to get new sleeves. Ill tear into it tomorrow and see what I find. Regardless, I still want a bigger engine, whether it'll be going in this frame or an entirely new bike :banana
 
#13 ·
Ok I'll answer some of your questions based on first gen 7/11 swaps and racing. Yes it is a simple swap and chances are your pipe may work with the 1100 motor. Yes the frame flexes but unless your really pushing it you will never notice. I've raced my unbraced 7/11 for 6 years and the only issue I've seen is on the chain side under swingarm tends to take some chain abuse. This motor makes 134hp at the rear and 82ft lbs of torque. I've raced my heavily braced 750 7/12 for over 14 years and broke one rear motor mount. Both bikes run 5.5 rear wheels with Bridgestone slicks on tire warmers so they've been flexed to the max. I always check the frames every morning before first practice and at the end of the day. The 7/11 runs the 750 box and 36mm cv carbs with Hindle exhaust. Can you tell the difference between the braced and unbraced frame, yes you can but both work pretty good once you get used to the tendencies of each. The funny thing I notice and it just may be in my mind is that when hard on the brakes on the unbraced frame it feels like the frame is bulging out right around the carb area. It's still stable but on this bike when you let off from hard braking you have to give it a split second to uncoil. Ha ha. After that it's stable mid corner and will twist up nicely coming out of a corner hard on the gas. I'd say there would be no issues using an unbraced frame for the street just take it easy on the wheelies.
 
#16 ·
Not good pictures OEM bodywork is 7/11. The bike with the 01 tail has been boxed and reinforced. If you look at the rear of the frame you can almost see the plate that was welded there as well as the gussets welded in the corner. The openings on the front are plated and welded and an additional cross beam welded in. Basically making a box out of the channel frame.
 

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#17 ·
Did a little research and it appears all years Katana AND Bandit 600's have the same stroke as a first-gen GSXR 750. that being said, I should be able to bore out the 600 block to a 749 so I could reuse my stock pistons? that'll save me a lot of money and rebuilding this 750, if the bottom end isn't screwed, shouldn't be a problem

Then I could proceed to the 1100... :)
 
#20 ·
an even better idea: use 2nd-gen 750 pistons. they are 73mm in diameter, my wisecos are 71mm. I can reuse my block, get a bigger motor, and reduce compression, all to my likings. doing some math, using these pistons will punch my motor to around a 815cc and maintain close to stock compression ratio
 
#22 ·
I've been using 2nd gen rods this whole time as they are stronger, so I know the piston pins shouldn't be an issue. boring from a 71mm to 73mm would mean 1mm off the existing walls, I think Ive seen this done before. I wonder if I would need to use a 2nd-gen head gasket as well
 
#24 ·
I read that article yesterday, a very interesting article indeed. It really is amazing how much potential these motors have and what can be swapped onto them. On that bike though, they used first-over pistons, the short stroke block with a spacer, and a ********. I'm wondering if I could bore out and reuse my long stroke block and Ill be using my stock head if it isnt trashed, its already been milled about "010. and has 18.5cc combustion chambers. I have a spare cylinder block that was unprofessionally bored to 71mm, Ill look it over and take it to a machine shop to see if boring to 73mm is a good option
 
#25 ·
so I measured the sleeve thickness on my spare block that was bored to 71mm and they are currently a tiny bit over 2mm thick, like 2.1mm thick. boring to a 73mm will leave about 1mm of thickness on the sleeves. is this safe?

If I did just go with the short stroke block, the stroke on those motors is 44.7mm and on the long strokes its 48.7mm. Would this mean Id need a 4mm thick block spacer?
 
#27 ·
finally got around to taking the top end apart, discovered piston #3 grenaded. keep in mind these are forged wiseco pistons, the motor mustve ran super lean and got super hot, idk. head and valves to my surprise look reusable, but I might be going with a different head this time around if I get a whole spare motor and if everything is in good shape. Ill post up pictures as soon as I get home from work, Ill find out also if the rods and bottom end are still in good shape
 
#29 ·
so I went to another salvage yard to see a '90 GSXR 750 that Ive had my eyes on for some time now but never really looked into it. I ended up buying the motor, thinking that because its a long stroke all the top end will easily swap onto my '86 bottom end. I found a dot on the head and the cylinder block was stamped 748cc. It wasn't until I got home and ran the engine code to find that this motor is actually off an '89 750 short stroke. with that being said Ive got some...

good news:
Its got the ********! bigger valves, cams, and runners, and everything so far looks pretty good on it. Its got the 73mm pistons and block that are fully intact, this means that I could possibly build a big bore ~815cc similar to the one in Powers of the Poconos. the engine came with yoshimura headers! engine turns over and is not seized

bad news:
its been sitting for a while. theres rust inside the cylinders, but it doesn't look too bad, maybe ball hone will take it all out. the piston rings are stuck, I need to figure out a way to free them up to see if they're salvageable. everything, as expected, will need a thorough cleaning. yosh headers will need to be blasted inside and out and repainted or plated. THE MAIN ISSUE: like everyone's been saying, these piston wrist pins are about 1mm larger in diameter than the ones on the long stroke motors. this means I will need to find someone who can bore out the small ends on my existing con rods while still assembled and on the bike, or get a small hone and do it myself. Im sure its possible, but maybe its a bad idea? the other option would be swapping out the con rods and getting the correct bearings. this would mean splitting the cases again, and id rather not go this route

or I could just replace the one sleeve and piston and continue running 12.5:1 CR 771cc....or add a spacer to drop the CR. what do y'all think?
 
#31 · (Edited)
they might've started making a little contact when the motor blew, it getting super hot probably made this happen. theres no signs on the valves at all, only the pistons. Im switching over my kibblewhite springs onto the ********, ill check if theres any damage to the seats or valve stems

I read through some old threads on here and found that I'll be safe boring out the small ends on the long-stroke con rods, I love this forum :)
 
#32 ·
my suggestion is disassemble your blown bottom end, check the #3 rod and bearing. Completely clean the engine and don't forget to drain and clean all lines and the oil cooler. Order one piston and sleeve and get it running. One final comment, get that bike to a dyno and get your carbs balanced and get that thing jetted correctly. Put the 88 motor in storage as it appears it will cost more to get that thing running than the one you currently have. Sorry for you luck but keep us all updated.
 
#34 ·
You can't enlarge your con rod small ends in-situ and you won't be able to hone them out 1mm while maintaining concenticity. I believe their finished size is achieved with a machine reamer - their factory tolerance certainly eludes to this.

It looks like bits of piston rattled around in the combustion chamber for a couple hundred times , so I imagine there'll be debris right through your engine. As mentioned, complete a full strip down, measure your no.3 rod for straighness, crank for run-out and clean every internal crevice and oil passage. Otherwise you're setting yourself up for a more spectacular engine blow next time.

While it's apart, sort your rod small ends (if it's possible/safe to do so).
 
#35 ·
I have the motor apart and Im glad I did, cleaned out a bunch of debris that I didn't imagine would be in there. Have the con rods out to get machined, or possibly. I got the pistons and rings soaking in marvel mystery oil for 3 days now and those rings are still really stuck. Maybe if I just assemble them as they are they will eventually break loose after a few heat cycles? Im also concerned that the cylinders might be rusted/pitted to the point of needing an overbore
 
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