Honda GB500 thread

Discussion in 'Old's Cool' started by Spurlock, Aug 27, 2016.

  1. XRLated

    XRLated Long timer Supporter

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    Wow. Thank you Bill. Studying and then filing away.

    Interestingly, a lot of GB clutch parts are still available on Partzilla, etc. I'll double check against the likely culprits on your list.
  2. XRLated

    XRLated Long timer Supporter

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    Has anyone experienced (or heard of) issues with the GB countershaft splines stripping out where they contact the countershaft sprocket? if so, are stripped CS splines a common problem or rare?
  3. Claytonroy

    Claytonroy Been here awhile Supporter

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    Not as a GB related issue, because the cush drive rear hub protects the driveline. I have heard of it happening to other RFVC based dirt oriented bikes though.
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  4. AnNoGBer

    AnNoGBer 89 GB500, 85 VF750S, 84 V65 Sabre, 85 V65 Sabre

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  5. Chankly Bore

    Chankly Bore Been here awhile Supporter

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    Don't quote me, but I seem to remember the XR600R countershaft was redesigned for more splines because of this problem. Incidentally the big Kawasaki singles have countershaft sprockets that look like the same dimensions
  6. XRLated

    XRLated Long timer Supporter

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    The XR650L got the redesigned more/narrower splines, but the bike's biggest design flaw is known to be stripping countershafts, which is why I was wondering if the fewer/wider-splined GB CS had issues: I was wondering if the new CS design for the XR650L was actually a step backward.

    Maybe or maybe not. In addition to the more/narrower-splined CSs on the XR650L, Honda also chose not to put a cush hub on the bike, and Honda chose to design a skinny sprocket with a consequently small contact patch along the splines for some reason. So, hard to know which caused the stripping, just the combination of no-cush and narrow-contact skinny CS sprocket, or if the more/narrower-splined CS also contributed. (For my XR650L, to reduce the stripped-CS Achilles heel, I've added an aftermarket cush hub to reduce the hammering and an aftermarket wide CS sprocket to increase the contact patch along the edith of the splines.)

    I guess there was some reason Honda went from few/wide to more/narrower splines, but sounds as if no one has first-hand experience of a CS stripping. All the used GB ones I'm seeing on the auction sites look in good shape. No doubt the cush hub is a big help.
  7. RowBust

    RowBust Long timer

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    Testing IMG_20201025_140651503_HDR.jpg IMG_20201025_140723767_HDR.jpg IMG_20201025_140705320_HDR.jpg
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  8. Wumpletoad

    Wumpletoad Last of the Late Brakers.

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    This usually has been an incipient, but often developed problem on many makes/types of motorcycle over the years. As the spline clearances increase with constant torque reversal, so the affects of the worn conditions become magnified; the cush element doesn't really change things much.

    For a long time, I always have assembled the front sprocket with Loctite Bearing Fit or equivalent. When left a couple of days before use, the inter-spline clearances are eliminated so there is no "rock" to initiate the wear process. Of course, this rather denies the advantages of Honda's "quick change" securing system and a puller will be required to remove the sprocket, but it will protect the gearbox shaft splines - I imagine new replacements are becoming scarce.

    W Toad.
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  9. Spurlock

    Spurlock Long timer

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    In my experience CS spline wear is much less common on road bikes than dirt, probably due to the less abrasive street environment and the fact that dirt riding usually entails much more on/off/on/off throttle work. I've always been in the habit of applying heavy bearing grease to the splines when fitting the sprocket, then spraying thick-setting aerosol grease into the splines at each chain lube interval. It flings out of course but in the meantime prevents erosion of the sprocket and shaft splines from rust and likely reduces wear.

    -Bill
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  10. AnNoGBer

    AnNoGBer 89 GB500, 85 VF750S, 84 V65 Sabre, 85 V65 Sabre

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    Early on made it a habit applying the rear brake before closing the throttle to keep force on one side of the tranny engaging points. Apart from actually minimizing the unrest of making up the slack it might also do good for the CS splines IMHO. Alas as yet I never had other reasons to pull and inspect it in my 14-15kmiles ownership of this GB500...
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  11. Bors

    Bors Adventurer

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    Is the GB250 as good and as sought after as the GB500?
    Reason I ask is there is a restored one for sale in my area for only $2000.
    Would this be a good buy?
  12. Spurlock

    Spurlock Long timer

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    From what I hear they are a great bike. But unlike the GB500 they were never sold in the US so parts would all need to be imported if you live here. There is often discussion of the GB250 on a Facebook group here: https://www.facebook.com/groups/1689304681350865/

    -Bill
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  13. squish

    squish Out of the office.

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    there’s likely some carryover to the XR650L which uses a very similar engine case design.
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  14. GBRiderinGB

    GBRiderinGB n00b

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    Hello guys and gals - I am new GB500TT owner having found a recent bike imported into the UK from Japan. I need your help, however!!

    I plan on doing a nut and bolt restoration and I would like to perform some sensible upgrades to the bike, so it ends up looking more like the faired machine in the second photo.

    So can anyone advise on the following;

    1. I believe the fairing is an OEM Honda option that was available for the GB400 - will it fit my machine and where can I find one?

    2. I would like to find a seat from a Mk2 (the one with the curved cowling) and have it painted and lined in the same burgundy colour. Again, some advice on whether I need the whole seat and whether it fits my bike or whether I can just buy the cowling and attachments would be greatly appreciated.

    3. I understand that a Jack Batson exhaust is the best way to go but again I am having difficulty trying to track one down. Any advice about how to find one would again be greatly appreciated.

    If anyone can help me source any of the above then I'd greatly appreciate your help. I'll follow up by posting photos of the restoration as it progresses.

    Attached Files:

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  15. Spurlock

    Spurlock Long timer

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    Greetings GBRider, welcome to this thread. Honda made the GB400 MkII which came with a fairing but those are no doubt very hard to come by. A fellow in your country has made fairing mounts for this fairing: https://www.feked.com/cafe-racer-ty...oQAnLKduzmWoXplyE_yzwbg1ekY_KPBiRJcQfrEQ1ITbA

    His name is Steve Graham Jones and he moderates a GB group on Facebook, here is a link to one of his posts describing his fairing mounts. He may or may not have plans to produce any more though.

    Set cowls are also very hard to come by. In the past there reproduction cowls sold on ebay Germany but I can't find them now.

    Jack Batson sells his exhaust systems directly. He lives in the US and can be reached at jeb858@gmail.com

    Here is his youtube video showing the system:

    -Bill
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  16. GBRiderinGB

    GBRiderinGB n00b

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    Thanks Bill for your quick and extremely helpful reply. It looks like the fairing on the bike I posted isn't a genuine GB400 fairing which has some 'ears' on each side, whereas the one in the photo is smooth - very much like the one that you sent the link. I'll get in touch and see whether this would do the trick - it certainly looks promising.

    I've found the company in Germany that makes the reproduction seat cowls - the issue is presumably they are made for the Mk2 seat which has the attachments for a cowl, whereas the Mk1 has the seat and cowl combined. Anyone out there have any experience with attach a cowl to a Mk1 seat at all??

    If someone would also come up with Jack Batson's contact details - or a JB GB500 exhaust gathering dust in a garage somewhere, then I'd be very happy to hear from you!
  17. Spurlock

    Spurlock Long timer

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    So does your seat not have the mounting holes for the cowl? I thought all the Japanese market GBs came with seat cowls. This image from cmsnl.com shows the Japanese GB seat as having the same cowl mounting system as others.
    [​IMG]

    By the way I believe that Feked fairing requires you to mount the clip-ons below the top bridge to clear the fairing cut-outs. Or maybe the fairing could just be mounted higher.

    Jack Batson's email address is jeb858@gmail.com

    -Bill
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  18. GBRiderinGB

    GBRiderinGB n00b

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    Bill, that's amazing, thanks. I was able to determine that the fairing is exactly the same one as the same picture is on the www.feked.com - so a fairing and screen is on its way!

    I have also been in touch with Steve Graham Jones who needs a minimum order of 5 mounting kits to produce the next batch - c'mon guys, you know you want one!!

    Thanks also for the email address of Jack Batson - I've emailed him and await his reply.

    Regarding the seat, I haven't yet seen the bike but when it arrives I'll see what the options are. Does anyone else out there know whether a seat cowl fits the Mk1 GB500 1985 model??

    Thanks so much for your help, I thought I'd need months to work out how to get everything lined of for the restoration......
  19. GBRiderinGB

    GBRiderinGB n00b

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    Bill, forgot to thank you also for the link to the CMS website - unfortunately it looks as though the special bolt and washer for the seat cowl is no longer available. Anyone any ideas where I might find a pair?
  20. Chankly Bore

    Chankly Bore Been here awhile Supporter

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    Further information. The Japanese market GB500 had the solo seat 77100-MK6-000, without the cowl and attaching hardware. The MK 2 GB400 had seat 77100-KN8-700 with cowl 77125-KN8-700ZB and attaching hardware; the special bolt could be made in stainless, the washer in some UV proof nylon type compound. The special nut, 61304-958-003 seems to be available.
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