Topic: My 1977 K7 Rebuild Story - Chapter 1

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So, after spending a few days driving around the neighbourhood I saw these things:


Clunky shifts with extra neutrals between 3/4 and 4/5
Incorrect carbs make it difficult to start and run properly
Occasional coughing and spluttering
A couple of significant oil leaks
Lots of dirt and nastiness
Lots of noise from the bottom end - sounds like chains...
Took it to the local dealer for a safety check - rear brake failed, front wheel bearings grinding, steering head bearings gone.

I took off the fairing - not part of my plan gave it an overall cleanup and decided that it should come apart down to the frame.

Look ok from 10 feet and I like it better without the fairing.

upside down picture it will open ok..

[Alan F.]

Sure is much more OEM Honda that way! Can't argue that. Can I ask what front and rear tire sizes it's wearing?

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I'll check that out don't remember off the top of my head.

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Front Dunlop D40-4F 100-90-19
Rear Dunlop D404 130-90-17

These are labelled tubeless - but of course have a tube in them.

[Alan F.]

Thanks, I'm totally on the fence about which rims to use, I should probably go with the 17" rear so I can ride 2-up.

Shinko 230 front
100/90-19
load index 57=507lbs

Shinko 230 rear   
130/90-17
load index 74 = 827lbs

1334lbs total load index front+rear
Bike is 550lbs wet,
Which leaves 784lbs for 2-up + gear

That should ALWAYS be enough.

[HondaMan]

Clunky shifts with extra neutrals between 3/4 and 4/5

This can happen with the K7/8 tranny when the shim on the end of the mainshaft was borderline not-thick-enough and now it has worn in a little bit. Not a big deal. Using proper oil (like 20w50 Bel Ray EXL Mineral) will go a long way toward 'fixing' it unless you're opening it up, then increase the shim to the next size up from where it is now.

Incorrect carbs make it difficult to start and run properly
Occasional coughing and spluttering

It sounds like these are related? What carbs does it have?

A couple of significant oil leaks
Lots of dirt and nastiness

Where?

Lots of noise from the bottom end - sounds like chains...

This is normal if the engine isn't smooth. The clutch has a special dual-steel plate in the stack, which has little springs in between the 2 plates. There are some rivets holding the plates to each other, and if they are a little bit loose this will amplify the 'noise' in an already-uneven engine. Also, running the correct oil type (see above) will help smooth this out as well.

[Alan F.]

Clunky shifts with extra neutrals between 3/4 and 4/5

This can happen with the K7/8 tranny when the shim on the end of the mainshaft was borderline not-thick-enough and now it has worn in a little bit. Not a big deal. Using proper oil (like 20w50 Bel Ray EXL Mineral) will go a long way toward 'fixing' it unless you're opening it up, then increase the shim to the next size up from where it is now.

I think my K8 will need this shim replaced for the same reason. Is there a fiche or part number I should look at?

Is it #24 ? at the lower left?
WASHER A, THRUST (25MM)
90458-506-810

[HondaMan]

Clunky shifts with extra neutrals between 3/4 and 4/5

This can happen with the K7/8 tranny when the shim on the end of the mainshaft was borderline not-thick-enough and now it has worn in a little bit. Not a big deal. Using proper oil (like 20w50 Bel Ray EXL Mineral) will go a long way toward 'fixing' it unless you're opening it up, then increase the shim to the next size up from where it is now.

I think my K8 will need this shim replaced for the same reason. Is there a fiche or part number I should look at?

Is it #24 ? at the lower left?
WASHER A, THRUST (25MM)
90458-506-810

Yep, that is the one! It came in 3 thicknesses to fit the width of the inside milled surface of the case at the end of the mainshaft opposite the clutch. In essence, it pushes the gearset slightly toward the clutch. The end gear (11) must mesh at least 3mm with the 4th gear (7), and 4mm is better if the forks will separate them at least 2mm when shifted out of top gear.

There were actually 4 thicknesses used when you include (0) spacer: 0, 0.1, 0.5, 1.0mm thicknesses. Most of the K7-8 engines I see have the 0.5mm spacer, while the lion's share of the F2/3 versions have the 1mm thickness. I have also seen them with 2 spacers: usually the 0.1 with one of the others. I think Honda had some quality-control issues with their machinists in the 1977-1978 engines?

[Alan F.]

Yep, that is the one! It came in 3 thicknesses...

Thanks! I'm happy to have identified it first try.
Past tense was intentional eh?  It's NLA now.

So, do we just add a thickness of oil impervious material between the case and existing thrust washer? Or is there a replacement for this thrust washer that we can add if we split cases and find it missing?

The bearing in that diagram #28 is a 6205 (ID 25mm, OD 52mm, 15mm width)

So I guess I want a thrust washer with a 25mm ID, but what OD and thickness?

[Alan F.]

Would you think this would do?

https://www.ebay.com/itm/INA-AS2542-Metric-Thrust-Bearing-Washer-FAG-Schaeffler-Koyo-SKF/162373690336?hash=item25ce39e3e0:g:JQwAAOSwNnRYi5i-

25 mm ID x 42 mm OD x 1 mm Wide, ships from California $9.99 free shipping.

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Hey - I did'nt check this post in a while thanks for the info.  Everything is in pieces in the motor at this point - I just started looking through the transmisson today - it actually seems in great shape for 70,000 miles - sitting for 30 years and bad maintenance by the po. Shift forks measure the same as the nos pieces I got to replace them, same for the fork shaft and drum. So I guess the old ones are going back in and I have nos spares. I'll have to find that thrust washer and measure it - I suspect its with the clutch parts.

All the gears look fine and no damage or serious looking wear - my only question would be about side ways "wiggle" of the gear on the splined shaft. If I grab a gear and try to move it sideways in its vertical plane - that is along the axis of the shaft --------II--------- i get a mm or so of sideways wiggle - how much is too much? and is it usually shaft wear, gear wear or both?

Guess its time to post part three.

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I also see that CMS has what they claim is that part 90458-506-810 - it seems to be part of many models and variants..6 euro 50..seems a lot for a washer but unobtanium..