My '79 Restoration

Hey, what projects are you planning or preparing for? CBX, other motos, workshop, WHATEVAH!
Russ
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Re: My '79 Restoration

Post by Russ »

desertrefugee wrote:Nice work. But, you mentioned that the bike was a low miles example. Any idea why all the wear and tear? In particular, the cam chain issues are surprising. Tensioner wear and stretched chain? Wouldn't that take a fair number of miles/kilos traveled?
Regardless, this one is going to be a gem of a restoration. Thanks for the travelogue.
Hi bud, I'm sure the mileage on the bike is correct (14,000 ish) as I have the original Dutch papers from its one previous owner and the clocks show no signs of being messed with. All the head cam journals also show minimal wear (you can still see original tooling marks if you zoom in on the pictures) with no ridges or grooves, the aluminium bearing faces would have been the first casualty.
As I said in the thread, the only wear problem I found was with B blade and chain. I'm positive this was due to the tensioner being forced past the locking bolt, the chain stretch was also the result of this. How many miles did it take to wear them out? might be 500, or 5,000, we'll never know.
Even now, months later, I still can't get my head round the logic and thought process behind this? The bike had been laid up for many years and I bought it from a dealer not the owner. The big plus point though, is that the chain didn't actually snap.
Russ

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Re: My '79 Restoration

Post by daves79x »

If I follow your explanation correctly, you say that the top tensioner rod was forced back into the head further than the lock bolt and it was just resting against it? I just don't think that's physically possible without something being broken with the tensioner. You must verify that your long tensioner is working correctly. Loosen the rear lock nut and see if it pops downward any at all. If so, that would indicate that it is indeed taking up slack in the chain. Failure to moves down does not mean something's wrong either, just means that the tension is correct, if it is working correctly. While the lock nut is loose, grasp the top of the tensioner with pliers and pull up. The tensioner should move upward quite a bit, which is tanking the tension off the chain. Tighten the lock nut, then hold forward tension on the crank (with the 17mm hex on the crank end). Then loosen the lock nut again and observe the tensioner popping downward significantly, to the correct tension again. If any part of this check fails, then something is wrong.

These camchains do stretch significantly, but not to excess in the stated mileage. I've seen 100,000 mile engines using the original camchains and the tensioners still take up enough slack. Somone screwed something up with your top tensioner and I'd be very careful diagnosing exactly what it it and what needs replaced.

Dave

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Re: My '79 Restoration

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Hi Dave,
Thanks for the tensioning explanation but I'm conversant with how they work and how to check and tension both chains correctly. Obviously the chain will not stretch to the point it had got to in one go, they must have repeated the operation several times to get to where it was - reading back through the thread I realise haven't made this clear enough. Each time they shoved the plunger in a bit more it wore a bit more material off both ends of the tensioner blade and also put enough tension in the chain to stretch it a bit further. I realise this must have been going on for a while and hadn't happened in one go.
I also realise that the chain stretches a bit over time in normal operation, but in no way was this a "normal operation" scenario, it got to the point it had because the rod had been physically forced in too far, and then nipped up.
daves79x wrote: These camchains do stretch significantly, but not to excess in the stated mileage. I've seen 100,000 mile engines using the original camchains and the tensioners still take up enough slack. Somone screwed something up with your top tensioner and I'd be very careful diagnosing exactly what it it and what needs replaced.
Dave
I did look at all the evidence to support this, it wasn't a knee-jerk diagnosis;
There was a hole in the cap that blanks the rod off - this was probably done to make it easier to shove the tensioning plunger in, rather than flip the cap out each time?
There was oil staining round the area, weeping both from out of the hole in the above mentioned cap and the hacksaw cut across the sealing face on the tensioner locking bolt - now repaired. This shows that they had been working in the area for some reason?
The locking bolt was behind the rod - the rod has not been shortened so the plunger movement must have come from somewhere else? i.e. the blade and chain
The blade had heavy wear to both ends shown in the pictures - obviously this had to be made from the chain?
The chain itself was 2mm longer than outside tolerance over the specified number of rivets - the only way I can see this amount of stretch happening is by over tightening of the chain tensioner?

The only diagnosis I can come up with to explain the worn chain, worn tensioner and hole in the plunger cap is the one I have explained in the thread? I would be very interested to listen to any other scenarios as to how this specific wear pattern would happen?
I have replaced the worn chain, installed a new tensioner (albeit a modified Honda one), welded and faced the head damage, done all the shims, installed and checked operation of both camchains and correctly tensioned them.

The engine is up and running - it is running very smoothly with no untoward noises, although I did have to replace the clutch dampers with "Six Centre" ones as it was a bit noisy around the clutch area on tick over.
Thanks very much for your thoughts on this though.
Russ

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Syscrush
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Re: My '79 Restoration

Post by Syscrush »

steve murdoch icoa #5322 wrote:And a lot of us here appreciate having tech stuff being explained in this matter.
Looking forward to the next installment.
:text-+1:
What he said! Thanks for sharing.
Phil in Toronto
A cool guy deserves a cool bike, a dork needs a cool bike...
Pics of Perry, my '79.

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wyly
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Re: My '79 Restoration

Post by wyly »

Syscrush wrote:
steve murdoch icoa #5322 wrote:And a lot of us here appreciate having tech stuff being explained in this matter.
Looking forward to the next installment.
:text-+1:
What he said! Thanks for sharing.
yup he's given all of us another option regarding cam chain guides when the world supply of oem guides is exhausted..:text-thankyouyellow:
CBX a work in progress, still improving...GS1150EFE completed and awaiting modifications.....RD350, remnants in boxes scattered throughout the garage

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Re: My '79 Restoration

Post by rupsus »

Did you install new rivets or re-used the old ones?

Russ
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Re: My '79 Restoration

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rupsus wrote:Did you install new rivets or re-used the old ones?
I used a drift on a press that was a lot smaller than the rivet diameter and it "unflared" itself as it was pressed out. I used the old rivets and a ball bearing to flare the end again, you need to be careful not to press it too hard and make sure the blade can rotate freely on the rivet.
Russ

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Re: My '79 Restoration

Post by rupsus »

:text-goodpost:

Russ
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Re: My '79 Restoration

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A bit more on the motor.....

All the engine orifices were blocked up, this was to stop any media getting into the motor when it was vapour blasted. Every hole had a machined bung made to suit, all made with an O ring groove or a gasket face so no chance of any blasting media entering the motor.
The motor sounded ok when it was running and I knew it would be a massive job to strip all the casings down. I could tell that the engine hadn't been stripped before so, considering the low mileage, it should be near enough as it was when it left Honda all those years ago.
New gaskets underneath the exhaust bungs to be squashed with the makeshift clamps - you can see four bungs and clamps fitted below.

All the shims were either swapped, changed or ground to get the optimum clearance. All back into position, the numbers are just to let me know where they were and the size.
IMG_0850.JPG
The sump was removed and pick up strainer was cleaned, this filter just stops any big bits going into the pump with a paper jobbie on the front of the motor doing the proper filtering. The gears all looked good with no marks or chips. On the outside of the motor left and right just above the filter there are the oil cooler flow and returns, these aluminium bungs had O rings to seal and clamping plates made.
IMG_0914.JPG
The filter housing always seems to get damage to the fins for some reason, the two outside ones needed building up on this one.
IMG_0909.JPG
All cleaned off with just a slight colour difference to say it's been repaired, when it's painted you won't be able to tell.
IMG_1334.JPG
Nylon bungs were turned up for the inlets and were clamped with the original carb rubbers as new rubbers were on order.
IMG_0685.JPG
Now that all the holes had been blanked off it was ready for it to be vapour blasted. A mate of mine has a machine that was big enough to get the engine through the door with a turntable so the motor can be turned through 360', the motor is 110kg (240lb) so is not easy to handle. The mild steel engine stand was designed for the vapour blaster in mind, when the first pass on the base was done the stand was turned on it's back and it could be blasted through 360' again. Pawel, my friendly Polish blaster, spent 4 hours doing this - FOC thanks to my mate Imran.
The result is a motor that is keyed and ready for paint. The clutch, ignition advance timing gear cap, crankshaft and camshaft end caps and alternator covers were also blasted and will need to be re-polished and fitted with new gaskets.
IMG_1366.JPG
All masked off and ready for primer and paint, this is the clutch side. I did remove some of the bungs and caps to see if there was any sign of blasting media behind them, luckily all had held back the pressure of the blaster. Obviously all the masking tape has to do is keep the paint out of the internals so it's a bit slap-dash.
IMG_1367.JPG
And the alternator side, showing caps with O rings for the starter, two for the head oil feed pipe, oil filler dipstick (a pain as the thread was a bastard pitch and form so had to grind a bespoke tool to screw cut it on the lathe), oil cooler feed and also nylon caps for the gear shift and sprocket seals.
IMG_1368.JPG
Next is engine paint..............
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daves79x
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Re: My '79 Restoration

Post by daves79x »

Did you put dummy bolts in for the chrome head bolts and shifter cover bolts, and others? My issue with this approach is that all the case bolts will now be painted instead of bright zinc. And all gasket edges will be also. It’s a lot of work either way, but I’d rather disassemble. I’m sure it will look great though!

Dave

Russ
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Re: My '79 Restoration

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daves79x wrote:Did you put dummy bolts in for the chrome head bolts and shifter cover bolts, and others? My issue with this approach is that all the case bolts will now be painted instead of bright zinc. And all gasket edges will be also. It’s a lot of work either way, but I’d rather disassemble. I’m sure it will look great though!
Dave
Hi Dave, I had a good think about it and, as the engine was a good runner and oil tight, I was happy I went the way I did. I know the edges of head and base gaskets will be painted but all the cover bolts were replaced or re-plated so they will look original. The rocker cover joint and all other "outside" gaskets were replaced with new ones.
Russ

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Re: My '79 Restoration

Post by jnnngs »

Russ,

Either way will work - I am with Dave and strip the engine down before painting. I just find "man handling" a complete engine is too much - but you have access to the necessary tooling so it works for you.

Good write ups tho', and appreciate the effort that goes into these things!

Paul.

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Re: My '79 Restoration

Post by steve murdoch icoa #5322 »

Thanks for the detailed write-up and pics, Russ.
I keep learning stuff from these projects.

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Re: My '79 Restoration

Post by NobleHops »

Coming in late to this thread, this is all super interesting to me as we do vapor blasting and I am duly impressed with the workmanship and effort that was put into sealing up this engine, along with all the other highly skilled mechanical work you have performed on the bike.

At the risk of pissing you off (I truly hope I won't) why didn't you simply soda blast it if your intention was to paint it? We have found that we get better adhesion by soda blasting with a coarse grade of soda, then rinsing, then an etch with an aluminum metal prep, then degrease with acetone and immediately spray. We can mask an engine for soda blasting in a couple of hours very effectively.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

Russ
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Re: My '79 Restoration

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NobleHops wrote: At the risk of pissing you off (I truly hope I won't) why didn't you simply soda blast it if your intention was to paint it?
Hi bud,
As I mentioned in the thread, a good friend of mine has a large vapour blaster and he did all the work free of charge (I did do a load of ally welding for him though). He got onto the grit suppliers and told them what we wanted to do and they specified the correct abrasive. When it was done it had a good key for primer and paint.
This was the reason I went this route.
Will post some pictures of the painted motor.

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