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Messages - K2-K6

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61
Desperately Seeking!! / Re: Main Jets 550 F2
« on: April 10, 2024, 05:12:56 PM »
 ;D bonus.

Certainly worth talking it through with him, may be able to help out.


62
Desperately Seeking!! / Re: Main Jets 550 F2
« on: April 10, 2024, 01:36:08 PM »
The type of place that would do them to spec is a clock repair business, it's sized right in their trade and experience.

They could likely and easily manufacture a set to spec too from simple brass stock in a small collet lathe. They're often making bushes (very similar in size) to repair old clock plates that have worn spindle holes. All reamed to accurate size in matching the tight tolerance needed.

Set of four aren't really much work in total labour time.

Could be an avenue to explore, perhaps if someone else needed some decent quality too.


63
CB750 / Re: Ignition system CB750 K3
« on: April 10, 2024, 12:55:04 PM »
Yes to ad hoc firing.

The coils, two leads ordinarily yellow & blue are down to points to give switching and timing, all left as normal.

The other two wires to coil are the supply of positive voltage to power the whole system.  Just give them the 12v supply and it'll be live.

Make sure you can easily disconnect (crocodile clip ?) In case you need quick shutdown  :)

64
Desperately Seeking!! / Re: Main Jets 550 F2
« on: April 09, 2024, 06:30:12 PM »
Considered resizing some ?

https://www.primetools.co.uk/product/stahlwille-11085-jet-reamers/

Reaming is really accurate to finish the bore in brass.

65
Misc / Open / Re: Spoke thread?
« on: April 09, 2024, 11:55:13 AM »

56 TPI equal to 0.454mm (0.45357) in possibly a Witworth thread form of included angle 55 deg seems to be somewhat in the ball-park for thread type  :)

Whitworth quite a possible form as date of record likely fed into bicycle std manufacture, with pitch rather than ultimate other decider to give characteristic tensioning effect that's consistent for X number degree of tightening turn to load the spokes.

Thread pitch desirable regardless of spoke gauge would seem logical to wheel building, and so giving likely hybrid to the thread form used, even today.

66
CB350/400 / Re: CB400 Four 50th Anniversary meet at David Silvers.
« on: April 07, 2024, 09:29:29 AM »
Was a really good day out last time there.

Meeting others from forum, great bikes, very interesting museum, different bikes running etc. Will plan to get there again for this one.

Also walked out along nearby coast, excellent Fish-n-Chips down by the beach in Aldborough before heading home to finish a great day out.

67
CB750 / Re: Opening that can of worms
« on: April 06, 2024, 02:33:35 PM »
Tentatively, looks like it may have the unique to F2 oil cooler plate behind filter housing (can't quite see in picture) which could mean F2 bottom end, or fitted to replacement engine as it's just a longer bolt used. Engine number will show case type anyway.

Top  "shelf" of head fins look more like K series as the F2 extended out more toward front wheelmin giving more cooling to exhaust port area.

As Bryan notes, could be K top onto F2 bottom end .... or K painted black to look like F2 original.

68
CB500/550 / Re: Comstar brake shoes
« on: April 05, 2024, 07:43:40 PM »
Any picture of wheel and hub to give idea of model ?

Likely that the CB650 was a swap in for original fitment, size parity of model. That seems to agree with your 160 x 40 mm dimension and listed some places as "321" code.

https://www.squaremotorcycleparts.co.uk/products/rear-brake-shoes-honda-cb650-cb-650-1983-1985

Is the whole brake "track" in the drum obviously used, or perhaps you can see a narrower band of witness mark if too  narrow a shoe has been installed.

69
CB750 / Re: Opening that can of worms
« on: April 05, 2024, 06:12:48 PM »
Looks full F2 rolling chassis etc, but motor appears previous to the F2  original.

Seems to have something like a Suzuki GS 750 type instrument binnacle though.

70
Misc / Open / Re: Oil temperature gauge
« on: April 05, 2024, 09:14:59 AM »
I spotted this oil temperature gauge for the CB400F on the Yamiya site, if my guess is correct it fits where the dipstick otherwise would sit. Has anyone got one, is it worth investing in? https://www.yamiya750.com/index.php?main_page=product_info&cPath=179_281&products_id=4119

Interesting to see what oil temperature is running at, but with no effect if you're not going to take any actions to change it.

Engine should run at 90C generally, but if too low temperature, winter for example being lower ambient (no thermostat on air cooled bikes) then a thinner oil viscosity could be appropriate, yes even with multigrade. Honda data says ambient below 15C then 20 viscosity is suitable.

If for example you, due to ambient and circumstances reliably saw 100C plus oil temps, then additional cooling and/or raised viscosity may be appropriate. 

The 40 viscosity in "general" use oil recommended does actually cover that 100C scenario for high ambient temperature running.

A temperature logging ability would be of more use in tracking and diagnostic analysis than a gauge.

71
CB500/550 / Re: Gammatronics
« on: April 04, 2024, 05:21:21 PM »
They make "supplementary" switching kits, much like Hondaman type unit, this to take triggering from points and then switch load to coils by solid state circuitry.

Unsure if that's what is meant in enquiry  ....

If that's the case, it looks reasonable, but would need a field test pilot  :) to give us a view of practicals here on the forum.

72
The supply to any electronic ignition could be wired direct to battery for the loaded circuit

With something like this https://www.12voltplanet.co.uk/standard-mini-make-break-relay-normally-open-no-contacts-12v-20a-with-fuse.html 12v relay incorporating it's own dedicated fuse as protection for that circuit only.

This would then only be triggered by switch on of ignition key, with fully independent direct supply to handle ignition system load autonomously.

73
The Black Bomber Board / Re: 67` Bomber running problems
« on: April 03, 2024, 09:02:05 AM »
I'd agree with Ash in checking #9 item first to see if any problem there.

Seems to be a detent position hold (generally they are) to prevent the shift drum moving without command or instigated by lever.

Sounds like it's OK inside the main box, else you'd likely get conflicts between gear sets if there's variation within that part of operation.

Also as Ash notes, checking the drum etc with clutch cover removed to see if there's reasonably positive "stopping" of the drum itself ( shift exchange lever removed) would verify the positive operation of that #9 mech.

74
CB750 / Re: F2 carb issues
« on: April 02, 2024, 04:27:14 PM »

Practical advice for OP to check nothing simple is catching you out on this set.

No carbs should "hang" on the throttle pull cable at closed position. This is ONLY facilitated by throttle stop screw next to cylinder #4 in providing absolute slide base position.  If there's any tightness in pull  cable at this position, then it needs adjustment to provide slack such that it can't interfere with complete "drop" onto that stop when you just let the twistgrip go.
Make absolutely sure there's no conflict with secondary cable throughout full twistgrip movement.  There's usually only adjustment on pull, with return being fixed.
You can remove the return cable while you try to diagnose fault, but advise to use when ultimately riding it though.

Idle mixture screws are set from a start point of 1 & 3/4 turns out from fully closed on the F carb set. Anything significant below that will likely give the symptoms described, effectively lean idle, with revs slowly drifting down and stalling. Make sure they are in the starting position if you don't know how they've been set.

Worth verification of these points to see if there's anything basic running you ragged.


75
CB500/550 / Re: CB550K1 - rear shocks replacement - actual options?
« on: April 02, 2024, 11:40:00 AM »
No help from me on the shocks.

But that's such a good picture of your bike Erny ... someone knows their shutter speed and aperture combination to pull those aspect together  :)

Perfect blur of spokes etc, while leaving good record of the bike moving.

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