Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: RGP750 on February 16, 2014, 08:37:37 PM
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I bought this 750 back in September ,A one owner from new even got original purchase receipt £890-00 and new 4 pipes (he didn't want to chance them going rusty so fitted motad, my Brucy bonus)
Thought i might keep it as original but after a few rides front break needs an overhaul Carbs keep blocking
so seeing as it was such a lovely day today decided to start.
Started to dismantle carbs but i'm stuck . Is the top shaft is it secured with captive pins?
see the photo (hope they up load )
Cheers Richard
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Yes they are, and it's not a good idea to try and dismantle them, the pins were never available as a spare part. Unless the action is stiff, leave well alone! Lubricate by all means, but they are a right pain to re assemble, and finding a way of securing them, and if you hit them too much the alloy can break >:(
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Hi thanks for that I thought they were, hence why i stopped.
The bike has done 25000, while they are taken down i was going to sonic clean them.
What is best for external finish,should i do a complete rebuild? if so can anyone recommend rebuild kit,
they range so much in price from £28 full kit of 4 to DS £80 ?????
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I have just found this out on my 500/4, I wondered why the shaft was hard to remove! Now I have to fabricate something to replace the pin that locates in a groove on the shaft to stop lateral movement.
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Hi have you drilled yours out?
I'll have a closer look at mine tomorrow,while i hear what hairy git says i think there is
more than enough material to tap3mm for a grub screw.
and be able to dismantle fully to renovate.
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Richard I've done quite a few 750 sets now. I break the carb units themselves down completely to ultrasonicly clean, but always clean the manifold / actuator bar as a complete unit wherever possible (so long as it has no excessive play / stiffness in the mechanism you should be fine). Just thoroughly clean, dry and lubricate after. I would always go for the honda gasket sets and try and use genuine Keihin pilot jets if possible. Keyster kits are 'ok' but the pilot jets in particular aren't a patch on the genuine keihin parts IMHO.
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I broke my carb set down to basic components - ie drilled out the pin in question. Would I do it again... mmm, not sure, a lot of stress for very little return... if you crack the boss etc you'll be wailing "why, oh why did I do this" long into the night! Check ebay for a spare before you commit!
The pin was a sod to drill out bring harder than its alloy boss, and, as suggested, I did then tap / replace with a grub screw (with honed end).
There was a thread on this a while back; forget which member but he (unfortunately) did indeed shag his shaft - admittedly through not realising there is a pin & welly'ing it out. Forget his repair... you'll have to hunt back if interested. (was the CB750)
Honestly, suggest you take James's advice / method...
Good luck,
Simon
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Thanks for the tips guys,think i'll keep it together then ,it is running free.
is David Silvers the best place for decent carb parts?
thanks again Richard
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Dave Silver / CMSNL / Fowlers for the Honda parts. NRP carbs for misc keihin parts (jets etc...)
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I have managed to drill mine out and will tap a 3mm thread for a screw, once in place will file flush and no one will know!
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Davis Silvers has aftermarket carb service kits at £16+the dreaded ,anyone have comments on these please.(aftermarket)
I would like to hear from other users before spending £80
thanks Richard
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Hi
I've just stripped said pivot pin (1975 K2) and damaged the alloy casting (that holds shaft and carb bank). It appears to have two removable keys in the shaft that slot into the casting in a set position (rotating shaft/casting) and then slide out easily. I've just bought another alloy casting from ebay (USA).
While I'm on subject - please see my new thread on carb bracket finish
Hope this helps (will let you know how assembly goes in few weeks after plating)
By the way - cruzimage on ebay (japan based) have kits for all 4 carbs for £28 - don't know what there like. I've tried to buy them but cant because says seller will not sell to me!
Phil
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Hi Guys
I had to replace the part where the cables go onto and for the life of me dont remember messing with that.On the spindle that goes right through the carb linkage there are half moon shaped keys that you have to get out,after which it all falls apart.
Cheers
Bitsa
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At the moment i have got the paraffin out and kept the assembly together cleaning up ok.
another result "her in doors" just gave me an electric toothbrush to help me clean in the intimate corners,works a treat.(think she will be asking me to decorate or something).
I have seen the 4x carb kits on ebay at £28, looked at feedback and one comment says they are out of tolerance so don't think i would risk it.