Author Topic: Nerdos' 750K3 restoration  (Read 19094 times)

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Offline bytio

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Re: Nerdos' 750K3 restoration
« Reply #100 on: June 19, 2014, 01:10:11 AM »
Have you checked the clutch spring length, I had a similar issue after replacing clutch springs that were new but too short

Offline Nerdos

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Re: Nerdos' 750K3 restoration
« Reply #101 on: June 19, 2014, 02:00:51 AM »
Small update here.  I took the clutch cover off and fumbled about with the lifter mechanism and refitted it.  Now there is plenty of resistance in the lever.  In fact, I would say way too much resistance.  The clutch cable was totally seized and the bike had not run since 1994 when I got it so I don't know how the clutch should feel but as I mentioned in a previous post, I have had 3 other SOHC4s in my time and although the 750 is larger and therefore presumably has a heavier clutch, I still think there is something wrong.  I can't check its operation right now as I am waiting to fit the new ignition system (arrived an hour ago but I am trapped at my desk).  As part of the rebuild I replaced the clutch cable with a genuine Honda part.  I also bought a clutch kit of plates and springs.  The springs were genuine Honda and the plates were aftermarket with the diagonal cuts on them.  Having absorbed the wisdom of Hondaman on these plates I decided to measure the originals, found that they were within tolerance and reused those.  So, in essence, new genuine Honda springs and cable with original, 72 vintage, clutch plates.  If anything it feels almost as if when I pull the lever something is bending inside the clutch.  It certainly does not give the feeling of something being moved as Soichiro intended.
Very much open to advice.  The bike has run for about 15 minutes on the bench so oil should have circulated thoroughly in the clutch and yes, I did oil the parts thoroughly as I reassembled.

Offline Nerdos

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Re: Nerdos' 750K3 restoration
« Reply #102 on: June 20, 2014, 12:31:57 AM »
DSS electronic ignition works a treat I am pleased to say.  Love the LED on the backplate so that you can set the timing initially without a strobe.

Clutch still a problem though.  It seems the clutch is disengaged at all times.  So, lever at the bars is in the correct position at rest and can be pulled back towards the bars by about an inch or so (but it's very stiff).  However, if you put the bike in gear with the engine running the rear wheel does not turn.  In fact there is barely any difference detectable if I stop the engine, put the bike in gear on the centrestand and rotate the rear wheel by hand or if I do the same thing in neutral.  I know I will have to pull the clutch out to find out what cretinous mistake I have made but if anyone can give me some pointers before I get oily I'd appreciate it.

Offline Nerdos

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Re: Nerdos' 750K3 restoration
« Reply #103 on: June 20, 2014, 07:32:17 AM »
Actually, this looks promising...
http://forums.sohc4.net/index.php?topic=36525.0

Will have to wait till Sunday to find out but it seems the most likely problem.

Offline Nerdos

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Re: Nerdos' 750K3 restoration
« Reply #104 on: June 23, 2014, 12:20:21 AM »
As suspected, the clutch inner was 90 degrees out of alignment with the basket.  Another easy to make mistake which I should have noticed. Now I have this cracked lifter plate to show for my incompetence and they're not particularly cheap to replace either.  D'Oh!  The clutch does work now though.  Not heavy in the slightest - I just can't go anywhere until I have replaced it.

Offline Nerdos

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Re: Nerdos' 750K3 restoration
« Reply #105 on: July 01, 2014, 07:09:05 AM »
CMS came to the rescue with a new clutch lifter plate and we're mobile.

The bike has just come back from its MoT test - not sure what your equivalent is called in the US but in essence it's a roadworthiness certificate.  Anyway, it passed.  First time.  Very nice too although I think probably a bit lenient on the part of the tester but I'm certainly not complaining.

The most pressing issues are cylinder 3 not firing and teh transmission.  I'm sure I will get the first problem sorted without too much fuss.  Number 2 had a blocked slow jet.  I cleaned that out and it started firing but number 3 then picked up the baton of faultiness and ran with it.  I've had the float bowl off and it's full of fuel and the slow jet is clear so that's just the spark to look at I guess.

The most worrying problem is I only have 1st and 2nd gear.  The lever will move up when I am looking for third and I can feel the resistance of the spring which returns the lever to the 'at rest' position but no 3rd gear. Nor 4th nor 5th obviously. I am pretty sure I checked the gears all engaged when I was assembling the engine.  It all seems so long ago now.
Anyway, any advice on my gearbox woes would be welcome.
In the meantime here's a picture of the machine just before its MoT (which you will have ascertained, does not include a road test).