Home

Welcome to my little Kawasaki KZ750 Twin info site.

To get started, click on any of the categories at the right side of the page or the links at the top of the page.ย  Or if you need to find something more specific (like “service manuals”), use the search at the top right.

Enjoy!ย  …and thanks for stopping by…

20070603fiberWrapExhaustb

236 Comments

  1. Biquetoast

    @Rhyno –
    Sorry, no, I wish I could help. I think it’s off to eBay for you…
    -‘Toast

  2. Rich

    โ€™Toast,
    I just smashed the black plastic rear Master cylinder cap. It’s the same size as the one off the front(I took it off to check). I did a web search for them but its turning up empty for part specifics. I would assume then that all caps the same size or something? I’d like to just get a cheap plastic replacement rather than buying an expensive chrome or metal cap. I know this may be a stupid question but, hay, you’re like Obe’one Kenobi of this stuff. so what’s the harm in asking…

    Dick

  3. Biquetoast

    @Rich –
    Good news! It appears that both the front and rear cap are the same part number on the ’76/77.
    I checked ye olde parts list (see it here: http://kz750twins.com/?p=418), and found that this is what you’re after:
    Front cap – 43026-003 CAP,OIL CUP (pg 46/47)
    Rear cap – 43026-003 CAP,OIL CUP (pg 74/75)
    I hope that helps…
    -‘Toast

  4. majo

    I hawe a 1978 z750twin scr…. great bike

  5. Mike

    Love the site as always . I have a question . I have oil dripping from the tach cable at the head . I know there an o-ring and a seal in there . Can the tach drive be removed (seal is out board)easily or is heavy disassembly required . Tired of wiping oil off my leg . Can’t find any reference to this in the manual . Thanks in advance for any help……..Mike

  6. Mike

    Sorry……77 if it matters

  7. Biquetoast

    @Mike-
    It’s been a while since I addressed this, but it’s something all 750 twin owners face at least once. I remember writing (and reading) posts about the right way to fix it… it involved taking off the valve cover, and maybe the head, and pressing out the drive, inserting a seal, bla bla bla.
    Wanna know what I did (and many others) to successfully stop the leak?
    1.) Unscrew tach cable from head
    2.) Insert small o-ring (can’t remember the size, but same as tach cable end)
    3.) Screw on tach cable
    …now this isn’t the *correct* way, but it forces any leaking oil up the tach cable and lubes it. I’ve done this on both my 750s, and I’ll probably do it again since the one o-ring is failing after about 7 years. Consider it a poor man’s fix, but it works pretty well…
    -‘Toast

  8. Mike

    Thanks Toast……..already picked up an o-ring . Guess a proper fix will have to wait till winter……which winter , i’m not sure of yet . Hate to stop riding with the weather so nice now in NY .

  9. Mike

    O-ring did the trick . On the road again……..

  10. KraZy750

    I have a ’78 KZ 750 twin and I’m looking for new piston rings and rod bearings. I’m not having much luck on my search. Any suggestions?

  11. Biquetoast

    @KraZy750 –
    I wish I could help… all I ever do is troll eBay to find things….
    -‘Toast

  12. lakesguypaul

    Hi All
    Great site and i am a newbie here. I bought a 1978 KZ 750B that had been sitting for over 10 years and was tore down to be painted and was wrecked in the front and had the whole front end replaced and i had to hand wire it back to stock.I got it running and it was running great. then all of a sudden it stated to miss badly and then wouldn’t start at all. carbs are redone,there fine, all new electrical, thats fine.It seemed like it wasn’t sucking gas in to the heads,I pulled the plugs out and checked the compression, problem, 74# on the left side 95# on the right.It had like 130# before.I only put like 32 miles on it and never rode it hard or red lined it.I can get a used motor for 150.00 or do you think it is just a problem in the heads? I wouldnt want to do all the work swapping out a motor and have the same thing happen again if i knew i could just have the heads redone and the bike would be solid.motor has 23k on it now. Thanks for any suggestions!!!

  13. TerryKZ

    I’m slowly pulling apart my ’76 KZ750B1, cleaning, repairing and replacing as I go. While cleaning all the gunk from under the rear inner/outer fenders and the tail piece, I heard something drop onto the work bench – it was a black plastic disc about 1.4″ in diameter. The hole it fits into is between the last mounting bolt at the rear of the tail piece and the tail light. I don’t see it on any of the parts diagrams – any idea what it is and what it is for? Looks like it was installed using a small amount of glue. Thanks for any information!

  14. LonesomeTwin

    Biquetoast!!!

    Long time no see. Nice to see someone carrying the torch, if you need yet another manual (I did mine myself, its small but good ๐Ÿ™‚ ) or some long-forgotten reviews or whatever, get back to me.

  15. Biquetoast

    @LonesomeTwin –
    Hi Steve, long time. Yeah, I’m still loving my twins, in fact just rode one to work today in December! I really wish I had more time to put into this site and keep it up to date, and make it really useful. Maybe when I retire… ๐Ÿ˜‰
    – ‘Toast

  16. kevin

    Toast, I have been building this kx750 twin for the last year now, I got it all put together, engine running great, except for one problem, it has a very hard time shifting into second gear, not that it is hard, but more like just goes into to neutral, but once in a while it will go into second gear, then will easily shift up and down, then will just start doing the same thing again, from first to neutral, like its not being full engaged up, but shifter wont go up any further. Any ideas? She wants to go and the few times I have been able to get it to shift up she is a runner.

  17. dee_sandy

    Hey Toast,

    I just bought my self a 1976 KZ750 and I’m working on getting her in running condition. Right now I’m working on the front brake, going to replace the brake line, but ran into trouble when the brake pipe was seized. I ended braking the brake pipe and now I’m having trouble finding another one.

    I’m going to be replacing the line with this: http://www.dimecitycycles.com/vntage-cafe-racer-caferacer-bobber-chopper-brat-custom-motorcycle-brake-parts-galfer-k7-stainless-steel-universal-brake-line-fk-u11.html

    And I found this brake pipe: http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-brake-parts-oe-honda-cb-450-750-hard-front-brake-pipe-line-45128-323-020.html

    But it says it’s for a CB450, and “May Fit Others”, but of course I don’t want to just buy it and see. Do you know where I could find a brake pipe or have a suggestion to not use a brake pipe? Thanks!

    -Dee_Sandy

  18. Biquetoast

    @dee_sandy –
    Boy, that’s a tough one. Those early 750’s have that solid brake line pipe because your front brake was in front of the fork… So the big problem is that if you use a hard pipe from another model, it may not fit and you cannot really shape it. On the other hand, you could figure out a way to run braided stainless steel line all the way form your brake switch to your caliper, and just skip the solid line. It may not look right, but with the correct fitting, it will work (but be careful where you route it). Or, just keep hunting for an original hard line…

  19. Biquetoast

    @kevin –
    Whoa… wait a minute… You mean it won’t shift into second when running? Remember, there’s a mechanism in there that stops you from shifting into second while stopped. I can’t remember what it’s called, something like “positive neutral idle…” or something, I forget.. ๐Ÿ˜‰

  20. kevin

    Yes. While running it wont shift into second, most of the time. I thought there was something like a neutral lock. Looks like balls fall into a notch one one of the shafts gears are attached to. I am just gonna buy new gears, shifter drum cam and shifter fork, that should fix problem. Its in the 80’s herevin phoenix, gotta ride.

  21. kevin

    Also toast, thank you for your time

  22. kevin

    Toast, so i I read what you had to say about electronic igintion opitions and to me it sounds like an igintion from a kz440 is best and easiest way to go, would you agree? As always, thank you vey much for your time and knowledge.

  23. Biquetoast

    @ kevin –
    I confess I have not actually done that mod with the kz440 parts, so I cannot say specifically.
    However, it sure does seem to be pretty straightforward.
    And while I have all the parts to do it… When the time comes for me to change from points to electronic on my second 750, I’m pretty sure I’m going to do the “half-Dyna” method, just so I can have the safety and reliability of *new* hardware. And since the kz440 parts are only going to become more rare as time goes on (meaning the cost goes up with scarcity), I’d rather have something that is replaceable upon failure, is future-proofed, etc. After all, I intend to have these bikes for many, many years….
    ๐Ÿ˜‰
    -‘Toast

  24. kevin

    Thank you for your time. Mechanic wants 1700 dollar’s to rebuild bottom end, found engine to buy for 250, looks like engine swap out for me this weekend………

  25. HowNowKaw

    Holรก Seรฑor Toast, et al.
    I just picked up a rolling basket today and am conflicted on direction. The serial number says it is #262 (BE000262 & engine number is BE000223) off the line. It is abused and somebody has swapped in a rear mag wheel that has a disk brake and otherwise it has just been neglected. It has FL title and three(yes, dear god, 3!) bills of sale on top of that so titling is possible but probably a PITA.)
    I like the bike but I already have four other variations of KZs so I don’t have to have it. So finally here’s my question:
    Should I put a bullet in its head and part this puppy and be done or does anybody have a nifty legal and yet cheap titled frame to sell?
    Thanks

  26. HowNowKaw

    (…crickets…)

    Do I need to put a coin in the slot? Is that how this works? I will give it a week or so then if I don’t have a titled frame and nobody want/needs parts I’ll separate the steel from the aluminum from the copper and so on.

    Grassyass.

  27. Biquetoast

    @HowNowKaw –
    Hi buddy… Naw, you just have to shame me into getting off my rump to respond… ๐Ÿ˜‰
    As for the bike, title, frame, etc… I’m afraid I don’t have a frame for ya, so we’ll see if you get any other responses. As for parting it out… It’s not a romantic notion, that’s for sure, but the parts *would* help to further bikes that need the love… Especially since it sounds like you have your hands full. Nice VIN and engine number by the way, those are about as low as it gets.
    -‘Toast

  28. HowNowKaw

    @’Toast
    Haha, sorry I was only trying to be a little cheeky. ๐Ÿ™‚ I am not a big fan of parting it out either and still might consider getting the paperwork straight on this because those are low VINs. I am not 100% that it can even be done in FL since they are so strict on dotted Ts and crossed Is and such. I would much rather see use come out of it. Alas, if it is not to be… well… anyway.
    Thank you greatly for creating a repository for the info on these bikes and for your response as well. We shall see what is in the cards for this one.

  29. Carlos

    @biquetoast
    hey man, I have a question. I can’t seem to get my pipes on right. The exhaust collars don’t exactly fit on the correct way but they are the OEM ones that I pulled off when I removed the pipes. How did you fit your pipes on when you reinstalled them?

  30. Hallsofstone

    Bought an ’82 and am having serious issues with fuel leaking out of the carbs. I’ve replaced the petcock and had the carbs taken completely apart, cleaned, and reassembled. Everything looked very good and normal. Even with the petcock in the “off” position it will leak. I assume it’s just the residual fuel in the lines from prior to the petcock closure. Thought it was just a stuck float or something but it wasn’t and I’m plumb out of ideas. Anyone else had this problem?

    Saw a video of a guy starting up his KZ and it catching fire. Would very much like to avoid re-enacting that scenario.

  31. Biquetoast

    @Carlos –
    Actually I don’t recall ever having had a problem with my exhaust collars like that. Could it be that there’s something stuck inside that’s stopping a good fit? Maybe the exhaust “crush washers” are deformed or missing?
    Sorry I don’t have anything that comes to mind…
    -‘Toast

  32. Biquetoast

    @Hallsofstone –
    Hmm… I had thought that the ’82 had a vacuum petcock, but clearly your saying it has an “off position” which makes me think you have an older-style gravity petcock.
    Bottom line is this… The petcock should stop the fuel flow. The float jets are great for regulating flow while running, but don’t expect them to hold back the river flow.
    Honestly, mine leaks a bit every year when I first put it in to service (and stops in a few days), as the rubber in the petcock re-expands from dry storage, but really it shouldn’t leak at all.
    So focus on your petcock, and make sure it really stops the flow. Or replace it.
    -‘Toast

  33. Hallsofstone

    ‘Toast,

    Really appreciate your thoughts on the subject. My bike is, seemingly, a conglomeration of parts from bikes older and newer. The petcock was just gone through last week. It is the three-place gravity style with “reserve”, off, and “Primary”…but you’re right, the fuel in the lines won’t get stopped effectively by the float jets and hence my leak.

    I think you’re on the same track I was and it’s great to have my suspicions confirmed. Can’t tell you how nice it is to have folks like you out there willing to help people out.

    Cheers,
    Hallsofstone

  34. Hallsofstone

    Well, unfortunately I was wrong. It is still the vacuum style petcock and it is still leaking. It still leaks when it’s not on the prime setting (which seems to be the forward position). Going to pull the tank and rebuild the petcock again with a fresh kit.

    I certainly hope I can do it right this time. Thanks so much for posting all those manuals! They are hugely helpful!

  35. Hallsofstone

    Any issues that I could run into with replacing the vac petcock with a gravity style mechanical petcock other than plugging up the vac line on the carbs? Anyone done this yet and if so, any pointers?

    If someone has installed something specific to replace that vacuum petcock, I would love to hear what that product was.

  36. Biquetoast

    @Hallsofstone –
    Hey does that’82 have a round screw-on style mount for the gravity petcock? I have a feeling it does NOT, but just want to ask. If it does, you can use a bunch of different ones, all the way from old Z1, to the early KZ750s, to Harley. If not, you’ll have to fish for after-market replacements at places like Z1Enterprises.com and such. On the complete other hand, now that we know it’s a vacuum petcock, it may only require a replacement bladder or rebuild kit.. You may want to check into that route too. Good luck, bro…

  37. Carlos

    @biquetoast Turns out I’m an idiot and was fitting the collars on the wrong side of the header flange. All good, pipes are on the bike.

    now I have a different issue… I’m decent when it comes to tuning bikes but this sucker has me at an impasse. I have the bike jetted exactly to repair manual specs (my bike’s an 82 kz750M1), and the only mod I made was I installed an adjustable jet needle. So it has 115 mains and 45 jet and the needle at the third groove. I cannot tune out a loss of power from 3/4 to full throttle; I was wondering if y’all had some ideas for me.

    I cleaned the air filter, checked for exhaust leaks (but that even that wouldn’t make sense bc I still have plenty of low end power), checked for intake leaks and I don’t think I have any. bike has good compression… I’m stumped.

  38. Biquetoast

    @Carlos –
    Okay, past one problem on to the next. ๐Ÿ˜‰
    Actually, I do have a thought on that… at 3/4 to full throttle, you are in a couple situations… I mean like fully on the “main” fuel/air circuits/jets, high fuel flow., etc.
    Whenever I get into a situation like you’re in, believe it or not, I go back and re-check the things that you probably already assume are correct. Like float level (I’m psycho about float fuel level), carb balance (you must balance them perfectly), clear internal fuel passages (I recommend dosing with 1/2 can of Seafoam per tank, maybe 2/3 in emergencies like this), timing and auto-advancer settings, and the main jet size and position.
    I have to admit, I don’t know much about the ’82 and it’s different carbs, but it sure sounds like you’re running lean up there on the mains. So is that the jet? Is that the fuel passages? Is that the float level? Check ’em all… Oh, and to clarify about Seafoam… When you’re trying to clean *internal* passages… You need to run the engine a bit with the fuel mixture to get it through passages that are not completely blocked (if yours are blocked, it won’t work). Then, over the coming days, the Seafoam slowly eats away the gummed up fuel inside the passages. Good luck!
    -‘Toast

  39. Hallsofstone

    Toast,

    I spent many hours researching and then searching for a petcock that fits. In the end, it took two separate trips of multiple hours, more research, multiple phone calls, and an hour of digging through a giant tub of a few hundred petcocks to find a couple that might work.

    Brought them home, installed and tested one, and got the bike running. Everything seemed fine until I was about to take off around the block and I see fuel just streaming out of the bike’s airbox again. Killed it and pulled the tank again. Had to drain it all back into a can.

    I’m really at a loss here. Carbs have just been rebuilt. Brand new petcock. WTF is going on here?

  40. Carlos

    @Biquetoast well, after much toil I finally got the bike to run how it’s supposed to. apparently the jet needles that I installed are considerably sharper than the stock needles, and it was running very rich, which I expected. shimmed the needles down and all is well. it was also running plugs that were way too cold for the use, so I had to
    install the recommended B6ES’. however…… the crankcase gasket started bleeding oil so I now have to repalce the damn thing. always something new.

    I did run a compression test on the cylinders and they both read 150 psi, COLD. naturally this seems too good to be true, so I’m gonna be doing another test ASAP.

  41. Carlos

    @hallsofstone
    you should look around eBay for a petcock; I’m sure someone has the exact one for whichever model you own. you should also check the petcock’s two gaskets and o-ring to see is they’re damaged of leaking. and, not questioning your intelligence, but make sure it’s on on and not prime… flooded my carbs way too many times.

    I have a comprehensive service manual in PDF format that I could send you, if you haven’t got one.

  42. Carlos

    p.s. the ignition timing for the M1 is transistorized, so it has automatic ignition timing. got lucky in that respect. a friend of mine jury-rigged a carb synch with some clear PVC tubing and two beer bottles and man, it works freaking great.

  43. Carlos

    @hallsofstone
    in fact, the only way (and I’m reasonably certain, but I could be wrong) that your fuel petcock could be leaking gas is if the o-ring sealing the lever is worn down and/or if the gasket in the sediment cup is broken.

  44. Hallsofstone

    @Carlos
    I’ve replaced the petcock with a non-vacuum style and capped all of the vac lines. Finding a petcock that fits the mount and meets the space/configuration constraints while flowing the proper amount of fuel (1/4 line(s))The original is impossible to find in new condition but rebuild kits are common. My goal was to eliminate vacuum actuation based on the suspicion that it was bleeding back into the carbs and airbox from the vac lines.

    In the end, sadly, it was both the vac lines and the residual flow in the hoses below the petcock. All of it back feeds into the carbs and flows out of the air intake valves. The floats have to be stuck as wide open as it gets. That means I’m into a full carb rebuild. My issues now include several stripped/damaged screws and a nearly felonious previous “rebuild”. I may have to replace the entire carb pair…which means find decent used parts, rebuild, reinstall, tune, go. Costly and time consuming.

    Does anybody know what the two fuel bung crossovers on these carbs are. More importantly, is one of them an overflow return? are there petcocks with a “send” and “return” setup? Would they help the problem?

    Hoping to have a bike to ride sometime this season.

  45. Carlos

    @hallsofstone
    if you’re referring to the three-way joints connecting the carbs (I’m assuming you have BS34s), one is a fuel overflow and the other is the fuel intake for the carb. if you just bought the bike, I suggest you perform a full carb rebuild/inspection anyway, because most people mess around with them without knowing what they’re doing.
    if you have a dremel, stripped screws are no probles; impact drivers and PB blaster also work wonders.
    you should also make sure that gravity actuated petcocks work on the BS34s. I can’t imagine why they wouldn’t, but I’ve made assumptions about these bikes before and it’s taken me nowhere good. the 78-79 model had BS-38s with a manual petcock and those carbs are a whole different beast.

    as far as the OEM petcock goes, you should at least try to buy a fairly decent, vacuum actuated petcock and use a rebuild kit. that’s what I did on this bike (KZ750-M1) and I’ve had no problems with fuel delivery to the carbs thereafter.

  46. Hallsofstone

    @Carlos

    According to my research, the fuel overflow can be tied into a return line to the tank. Both of the compatible gravity fed petcocks I found for this bike have two 1/4″ bungs on them. Right now, I’m trying to figure out if the extras are specifically for a return line or if they are there for twin supply (like for a duel inlet carb setup, or secondary reserve supply).

    The gravity fed petcock supply should operate just fine on this carb setup because it’s basically the same delivery principle as vacuum actuation. The dilemma here is whether or not to cap off the vac lines on the carbs or simply leave them connected directly to the vac bung on the air box. They were designed to be connected, so I’m going to try to reuse some of the original vac lines to reconnect the carbs to the airbox today. I’m curious to see how that would effect the bike while running.

    I also have an appointment with my favorite mechanic. He’s owned about six of these old KZ’s. He offered to help me work through it this week. I’ll pop back on here and offer up the details once we’re done. Someone else may run into this same issue and benefit!

  47. dave the welder

    hello all i just got a 82 750 CSR.mostly all there except for the air cleaner assembly and both side covers.was wondering is this specific for this model only or are there other years/models that will interchange thank dave

  48. Carlos

    @hallsofstone would love to hear an update on your predicament, if that’s alright.

    @bikestone and everyone else
    so the bike is running excellently now. smooth power delivery as far as you can get with these CV pos carbs, and the milage is around 50 mpg. as part of the restoration, I

    a) ran a compression test on both cylinders
    b) checked the cam chain tension and adjusted accordingly
    c) checked the swing arm and its bearings while the wheel bearings were being replaced
    d) replaced both sets of wheel bearings and replaced the entire brake system

    however, when I ride it, while I’m just cruising, I feel this persistent sort of harmonic vibration. these bikes shake a whole lot when accelerating, but this vibration comes, for a lack of a better word, in waves. in vibrates, doesn’t vibrate, vibrates, doesn’t vibrate… kind of like that.

    now, the question is: what could it be? the bike, prior to falling into my ownership had about 12,000 miles on it, so I really doubt that the balancer chain and/or the balancer mechanism is timed improperly or not working altogether. could it be the engine mounts or something along those lines? I’m convinced the vibration is pretty harmless because I’ve ridden this a lot and for long periods of time and nothing has happened to it so far. any thoughts would be greatly appreciated!

  49. Carlos

    ^ TOTALLY meant @biquetoast I’m not entirely all there today haha

  50. Biquetoast

    @ Carlos –
    Good to hear about all the good runnings…
    But I have a question back at you…
    When you feel that crazy “wave” of vibration… Could it possibly be your drive chain flapping back and forth on the bottom?
    Okay, I know it sounds crazy, and not that I’d ever look down at my drive chain while riding (because that’d be dangerous), but when I’ve felt those exact things, I’d look down and see the bottom “return” part of my drive chain flapping left and right in some crazy harmonic vibration. And a little throttle control and it goes away. Now, I’ve always thought I was nuts about this, and nobody’s ever corroborated my symptom, but I’ve had somme luck mitigating this by adjusting the rear wheel alignment just a tad. Anyway, check that (or not, if you think looking down like that is dangerous), and let me know if that’s what you have too…
    -‘Toast

Leave a Comment

Your email address will not be published. Required fields are marked *