Author Topic: 750 K2 Strip & Rebuild - help please  (Read 20965 times)

Offline Trigger

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Re: 750 K2 Strip & Rebuild - help please
« Reply #180 on: July 21, 2022, 08:11:33 AM »
Not sure what year they started all the superseding from chrome to BZP as, in the UK we had long running models like the CB750 and CB500 four.
By the time the CB550F1 came out there was very few chrome fasteners on the bike.
The only bolts i can think of that were not changed to BZP was, the indicator M6 bolts, top yoke bolts, nuts, washers , handle bar mounting bolts and the disc mounting bolts  ;)

You have also got all the different size nuts which may have the same thread but the A/F ( spanner size) were different. One of my pet hates was to see M8 bolts on the fork caps with a 12mm A/F when they should be 14mm A/F  :o 

Offline Bryanj

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Re: 750 K2 Strip & Rebuild - help please
« Reply #181 on: July 21, 2022, 08:20:07 AM »
Trigger, the spanner size was because Honda used Japanese metric standards not ISO metric standard, you would have really hated the big tankers built in Japan, it was a nightmare after drydocking a German built one in Yokohama

Offline Trigger

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Re: 750 K2 Strip & Rebuild - help please
« Reply #182 on: July 21, 2022, 02:53:12 PM »
Trigger, the spanner size was because Honda used Japanese metric standards not ISO metric standard, you would have really hated the big tankers built in Japan, it was a nightmare after drydocking a German built one in Yokohama

I know that it is all Japanese industrial standard Bryan, there are some M8 nuts with a 12mm spanner size and some with 14 mm spanner size. Also M10, 14mm spanner size and M10, 17mm spanner size, M12, 17mm spanner size and M12, 19mm spanner size and not forgetting many washer and nuts at different thickness  ;)

Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #183 on: July 21, 2022, 04:22:00 PM »
All rather confusing for the restorer as the fastener Part # does not specify the bolt’s finish. This arvo I googled the common part # for the starter cover bolt (CB750, K1, K2), and was ‘shown’ very ordinary (Honda packaged) BZP bolts. How does one know what is right?

Moving on, I looked more closely at the Sandcast Starter motor cover plate, and noted it too (just) fails the feeler gauge check… ie there is a discernible 0.5mm gap. I’m beginning to reckon the plates are non-OEM as everything else looks correct and original.

In the case of the K2 rebuild, and the new Yamiya plate, I’ve ‘fixed’ the problem by adding a thick SikaSeal adhesive base to the packing seal, ie raised it 1.5mm. For now, it’ll do until I get to the bottom of the issue….

One last query; one starter cover plate is mirror chrome, and the other a brushed chrome finish. Which is original pls?
« Last Edit: July 21, 2022, 04:24:56 PM by Lobo »

Offline Oddjob

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Re: 750 K2 Strip & Rebuild - help please
« Reply #184 on: July 21, 2022, 04:56:50 PM »
One nut that seemed to retain the chrome look was the upper shock absorber cap nuts and the big thick washers behind them.

Another was the pinch bolt for the rear brake arm on the rear brake plate. Same for the gear lever pinch bolt, some changed but some retained the chrome one.

Some fasteners do use an identifier on the end, modern Honda JIS screws for instance can be identified when they are black and also when they have a captive split washer, for use on handlebar switch gear for instance.

Oh just thought of another chrome bolt, rear number plate bracket ones, the 4 which attach it to the guard, they tended to be chrome with chrome washers, as did the rear light ones come to think of it.
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Offline Trigger

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Re: 750 K2 Strip & Rebuild - help please
« Reply #185 on: July 21, 2022, 06:49:06 PM »
All rather confusing for the restorer as the fastener Part # does not specify the bolt’s finish. This arvo I googled the common part # for the starter cover bolt (CB750, K1, K2), and was ‘shown’ very ordinary (Honda packaged) BZP bolts. How does one know what is right?

Moving on, I looked more closely at the Sandcast Starter motor cover plate, and noted it too (just) fails the feeler gauge check… ie there is a discernible 0.5mm gap. I’m beginning to reckon the plates are non-OEM as everything else looks correct and original.

In the case of the K2 rebuild, and the new Yamiya plate, I’ve ‘fixed’ the problem by adding a thick SikaSeal adhesive base to the packing seal, ie raised it 1.5mm. For now, it’ll do until I get to the bottom of the issue….

One last query; one starter cover plate is mirror chrome, and the other a brushed chrome finish. Which is original pls?

The cover plate is flat mirror chrome. I have had a look at all my starter motor cover on 750's and all sit flat, not sure if i got them from Yamiya though  ::) If you are not having any joy contact yamiya as, they will take a new one out of the packet and test fit it to one of there bikes  ;)

Offline Trigger

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Re: 750 K2 Strip & Rebuild - help please
« Reply #186 on: July 21, 2022, 06:53:16 PM »
One nut that seemed to retain the chrome look was the upper shock absorber cap nuts and the big thick washers behind them.

Another was the pinch bolt for the rear brake arm on the rear brake plate. Same for the gear lever pinch bolt, some changed but some retained the chrome one.

Some fasteners do use an identifier on the end, modern Honda JIS screws for instance can be identified when they are black and also when they have a captive split washer, for use on handlebar switch gear for instance.

Oh just thought of another chrome bolt, rear number plate bracket ones, the 4 which attach it to the guard, they tended to be chrome with chrome washers, as did the rear light ones come to think of it.

The rear number plate special bolts had chrome washers under them. Not all SOHC's and years came with chrome rear light bolts in chrome and the ones that did had chrome washers beneath them  ;)

Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #187 on: July 24, 2022, 12:15:56 PM »
Rebuilt the forks today, and tomorrow, will fill with oil.

Any recommendations (oil grade) to go for, or just stick with book figures.

Ta…

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Re: 750 K2 Strip & Rebuild - help please
« Reply #188 on: July 24, 2022, 12:31:07 PM »
Motul 10 viscosity if available in your marketplace.


Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #189 on: July 26, 2022, 12:45:59 PM »
Thanks Nige… Agip oil went in as locally available.

At last the rebuild begins, with the engine into the frame today. Am lucky enough to have an electric hoist in my garage roof - worth its weight with the Moto Guzzi rhinoceros thing…
All went smoothly with no dents nor scratches anywhere; my missus is becoming better and better @ such helping chores.

Q - the various fork bolts. (1) how come there aren’t D washers at every clamping joint, and, (2) should you expect the D washers (Fork upper bridge) to be loose or clamped at the 6ft lbs torque book figure. Mine, currently are rattling, though tbh I’ve only done them up guesstimate tight for now.
« Last Edit: July 26, 2022, 12:52:39 PM by Lobo »

Offline Oddjob

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Re: 750 K2 Strip & Rebuild - help please
« Reply #190 on: July 26, 2022, 01:29:10 PM »
If the top yoke clamp bolts are 8mm then it's supposed to have D washers and yes they'd not rattle.

The pinch bolts are also supposed to be fitted so the nut is at the lowest point, so back of the yoke, this is so if the nut ever came undone only the nut and spring washer would fall off, if fitted the other way the entire bolt would slide out. Added bonus to doing it this way is that IF the bolt ever slid out it would almost certainly hit the tank, that would most likely dent or at least ding the paintwork due to the weight of the bolt, you may get away with the nut hitting the tank.
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Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #191 on: July 26, 2022, 02:03:54 PM »
Cheers Ken, interesting and sensible…

Wherever possible, I’m trying to be totally accurate with the rebuild, and what you write is in confliction with my Honda Parts diagram - which shows the bolt inserted from the rear!

Was it a later Bulletin perhaps? Regardless, I may well take your advice on this one; tbh I’ve been slipping in the odd extra washer as can’t bear the thought of raw spring washers against the new & pristine powder coated frame.

(…just had a thought: if a stanchion pinch nut disappears whilst riding I’ll have far bigger problems than a scratched tank to be worrying about 😂)
« Last Edit: July 26, 2022, 02:21:12 PM by Lobo »

Offline Oddjob

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Re: 750 K2 Strip & Rebuild - help please
« Reply #192 on: July 26, 2022, 02:38:07 PM »
That's true. However by putting the nut and spring washer at the bottom it's also visible to you as you ride. So if it was coming lose you'd have at least a chance of spotting it. Other way round and they are slightly hidden and thus first thing you may notice is the bolt missing entirely. The bottom pinch bolt would hold the leg I'd imagine until you got round to fitting a new bolt. Trouble is those bolts are chromed so they tend to be special order etc and not cheap.

If the bolt was the later 7mm bolt there are no D washers fitted to those but a K2 would have the 8mm ones as standard IIRC.

Parts book is fine for seeing correct parts but not for orientation IMO.
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Re: 750 K2 Strip & Rebuild - help please
« Reply #193 on: July 26, 2022, 02:51:32 PM »
I can see the logic of fitment opposite to manual but have always done it as illustrated by Honda, never had one come undone on any bike though.

The arrangement they've got may (you'd need to check bore size etc) be such that the placement of the bolt head and restricted by the D washer keeps the alignment of the bolt coming through the front of the casting. That could be to prevent the bolt shaft pulling inward toward the stanchion and maintaining a flat pull on the front of the casting. The front hole can then be "floating" without binding to  give more than desired bend to casting, in other words trying to keep both bolt head and nut faces planar to each other.

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Re: 750 K2 Strip & Rebuild - help please
« Reply #194 on: July 26, 2022, 02:54:47 PM »
Similar to front spindle clamp orientation.

The lower triple clamp is also steel and much less vulnerable to excess bolt load than the top aluminium casting, which takes most of the chassis load on it's own.

 

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