Author Topic: 1975 400/4 project  (Read 3564 times)

Offline Sprocket

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Re: 1975 400/4 project
« Reply #60 on: February 11, 2019, 01:31:24 PM »
So I've popped the engine apart! I've discovered the head gasket was installed upside down, a whole load of gunge in one of the oil restrictors and two of the pistons' rings have broken. But, I consider this a bit of a 'win' as there doesn't appear to be any damage to the pistons, bores, valves etc.

I'm going to take the bits into a local motor engineering company, I called them up today and they said they'd give me some advice if I needed it, but bring the bits in to look at and stroke beards by.

All the pistons have 'Honda written on them, so I would guess they're original and thus I'd be getting the standard sized stuff from DS to replace the rings. Sound logic?

The bores are completely smooth, as you might expect in a 60k mile engine! Am I to expect the engineers to recommend a hone and just replace the broken piston rings, or does anyone think I'm being far too naive?

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: 1975 400/4 project
« Reply #61 on: February 11, 2019, 02:44:05 PM »
At 60k, i would be expecting a lot of things to be beyond service limit now. Even if everything looks ok to the eye, everything needs to be measured, including the bores, to see if they are close to or beyond spec. A rebore is most likely at that mileage. Are your Honda pistons / rings standard size or oversize?. I'm assuming if the head gasket has been installed upside down, someone has been in there before.
And don't forget to fit new primary chain when you rebuild the bottom end and cam chain, totally false economy not to. And make sure your local engineering shop know about early Honda engines, the tolerances are very, very tight on these old girls.
« Last Edit: February 11, 2019, 03:00:11 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

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http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Sprocket

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Re: 1975 400/4 project
« Reply #62 on: February 11, 2019, 04:12:41 PM »
At 60k, i would be expecting a lot of things to be beyond service limit now. Even if everything looks ok to the eye, everything needs to be measured, including the bores, to see if they are close to or beyond spec. A rebore is most likely at that mileage. Are your Honda pistons / rings standard size or oversize?. I'm assuming if the head gasket has been installed upside down, someone has been in there before.
And don't forget to fit new primary chain when you rebuild the bottom end and cam chain, totally false economy not to. And make sure your local engineering shop know about early Honda engines, the tolerances are very, very tight on these old girls.
:) I was hoping you'd reply! I don't even know how to measure pistons to see if they're standard or oversize at the mo, so I expect I'll be leaving it with the engineers for a little while so they can measure stuff and advise. It certainly seemed like they were up for telling me what I needed to get, and letting them do the work I can't. I've previously experienced people getting a little testy when you say you just want them to do that. (Car stuff - "we can't give you a warranty, so don't come crying", etc)

I have used the engineers before for a couple little bits so I have a reasonable expectation they'll know what they're doing. I'm just keen to do as much as I can, and learn along the way.  8)

Offline Nurse Julie

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Re: 1975 400/4 project
« Reply #63 on: February 11, 2019, 05:41:25 PM »
Yes, it's great to DIY and learn but it can be a costly exercise as well. You will need to take the Haynes Manual with you to the engineers as it has the service limits in. Also, if you found crud in a restrictor jet, you need to strip the complete engine, thoroughly clean all oilways and the main oil gallery as that crud had come from somewhere and was travelling to somewhere else so anything or everything could be blocked or full of sludge.
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Sprocket

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Re: 1975 400/4 project
« Reply #64 on: February 12, 2019, 08:05:06 AM »
Yep, when I noted the positive stopper had broken, I made a mental note it's all coming apart anyway. I've been following the youtube videos and comparing to the book so far, and there's been relatively few show stoppers. Combine those two resources with you lot here and I reckon I'm laughing! :)

Costs wise, I reckoned a rebuild would set me back about £1000 but that wouldn't include any massive surprises. So I think we're still good at this point!

Offline rozabikes

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Re: 1975 400/4 project
« Reply #65 on: February 12, 2019, 10:25:58 AM »
Re U-tube on this. There is a pretty good strip / rebuild thread out there but remember when I was taking clutch off, I referenced that bit in the video as I was wondering how he locked the engine. Haynes made no reference either. He said something like his mate had a special tool (that we all know you need). However the video then flicked straight into clutch having been removed, so you did not see any locking method used.

One day I'll have the time to restore it, not just talk and dream....

Offline Sprocket

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Re: 1975 400/4 project
« Reply #66 on: February 12, 2019, 10:30:55 AM »
See I was worried about that too, but in my case the large nut wasn't in any way tight. After I unbent the retaining washer thing, I could unscrew it without needing to even use the clutch socket thing I bought! I feel like it's one of those that you need to 'shock' loose if needs be, with an impact driver.

Offline rozabikes

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Re: 1975 400/4 project
« Reply #67 on: February 12, 2019, 11:26:50 AM »
See I was worried about that too, but in my case the large nut wasn't in any way tight. After I unbent the retaining washer thing, I could unscrew it without needing to even use the clutch socket thing I bought! I feel like it's one of those that you need to 'shock' loose if needs be, with an impact driver.
Just locked the gearbox via final drive as suggested on this very forum.  It was just if you are gong to do such a video and take all that time, why not cover difficult parts, assuming the idea was to help others. :P

I had mislaid my tool for the job but far too impatient, so fashioned a 2 prong version with some flat steel. Did the job with adjustable spanner for leverage.
One day I'll have the time to restore it, not just talk and dream....

Offline Bryanj

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Re: 1975 400/4 project
« Reply #68 on: February 12, 2019, 01:00:31 PM »
Kawasaki had a workshop tool that was big molegrips with bent long legs that clamped into the inner splines, was quiet cheap when i was doing them so bought one

Offline Sprocket

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Re: 1975 400/4 project
« Reply #69 on: February 28, 2019, 07:02:42 AM »
So after some flu and other 'life events' I finally got round to taking the most final step and splitting the cases. Stubborn front mount bolt still there, I worked around it with a spanner and have left a bolt in for the engineers to fix. Also there's what's left of a sump bolt still in the bottom half, I may have a go or I may let them deal with it.

As expected the camchain adjuster locking bolt thread has completely gone though, which is disappointing. I was so careful not to touch it until I'd split the cases! I wound it in, looked at the end for any sign of mushrooming, there was none. Extracted what I thought was a little loose gunge on the end, then gradually back and forthed it. Bolt looked ok, but the thread inside has completely disappeared.

I did note the bolt wasn't straight too, which I assumed was going to be a problem. But on inspection inside, there is a drilling hole in the casting that isn't straight, so I'm not sure that's actually a problem. Ah well, will let the engineers sort it out.

Overall was pleasantly surprised there was less loose metal in there than I was expecting, but I did find the source of the other mysterious swarf in the sump. Top gear. Seems like it could be a common issue too, judging by how many gear sets are for sale without this one, or with it damaged  ;D

Offline Sprocket

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Re: 1975 400/4 project
« Reply #70 on: April 07, 2019, 10:23:45 PM »
Have received the cases and barrels back from the engineers. Front mount drilled out with a long drill. Cam adjuster repair kit fitted (front case needed machining a bit to get the internals to line up properly). Barrels measured and would you believe were still within tolerance for a standard set of pistons. The guys told me I could probably put the originals back in with a new set of rings if I wanted, but they always recommend new ones on historic rebuilds like this. The grooves were just over tolerance on pistons 1 & 4. Anyhoo, ordered a full set of standard ones from cruzinimage after some research and will see how I get on.

Slight pause in proceedings now while I wait for a power supply for my zinc plating kit. Silly me thought my battery charger could be fooled into powering it. Didn't check until I'd acid stripped all the bolts for the oil pump, so even though Julie got me a set of O rings super quick (thanks again!!) it's gonna be a week or so before I can refurb it.

Have a set of gears from a 14k mile bike too, from USA. They look a great deal sharper than the ones that came out, so that's a good sign too. Oh, and I also got a horn from a CL360 which comes with the same cover and bracket. Shipping was astronomical but the part itself was about $9. Still no idea if it works yet though, the bike is up tight against the wall now while I concentrate on the engine.


Offline Sprocket

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Re: 1975 400/4 project
« Reply #71 on: June 11, 2019, 08:18:48 AM »
Quick update, I haven't stopped working on it!

Cleaning, cleaning and cleaning has finally meant I can't find any traces of dirt on a clean cloth when I touch any part of the cases, inside, outside, oil galleries etc. Some of those 90 degree bends inside are almost impossible to get to, but many cable ties and a couple clothes hangers put their lives to the cause!

Have decided to get all new bearing shells, a couple might have been able to be cleaned, but I figured I may as well get it all sorted once, rather than pull it apart again in future. An eye-watering £218 to Long John Silver in exchange for 18 bits of curved metal...  :-X

Crank is pretty much assembled now, torqued up the big ends slowly, then again the following day and a satisfying teeny blob of green paint on each nut. The little things that provide satisfaction!

The gear clusters I got from America have been knobbled. In the countershaft one of the oil plugs was missing, the other punched through with a screwdriver. Although the old one I had was complete, I had no way of getting them out. So I went to see the friendly engineers and am waiting for them to turn down some brass to fit. While I was there they did mention they look like 11mm core plugs (which I have spotted online for a few quid) but I feel like getting something engineered to fit properly is the safest bet.

Spent some time measuring up the piston rings in the kit I received from Cruzinimage. All within spec, nothing needed filing back at all. Managed to bust a black ring assembling one of the pistons though. Top marks for customer service from the seller though, I explained I did it and they came back with a pretty reasonable price for a replacement set (2 rings and a 3 piece oil control set).

Jury is still out on what to use to bond the cases back together. Hondabond, Yamabond, Threebond, Toothpaste, Silicon Sealer, Sand & Cement, etc... Answers on a postcard please...

Offline Laverda120

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Re: 1975 400/4 project
« Reply #72 on: June 11, 2019, 08:34:31 AM »
Keep going 👍. Post some progress photos if you can. I use Honda bond for the cases.
1976 Honda 400/4
1977 Honda 400/4
1981 Honda CB250RSA
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1982 Laverda 120 Jota
1924 Triumph 550SD
2012 Stanley Battery Drill

Online K2-K6

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Re: 1975 400/4 project
« Reply #73 on: June 11, 2019, 08:38:51 AM »
"Jury is still out on what to use to bond the cases back together. Hondabond, Yamabond, Threebond, Toothpaste, Silicon Sealer, Sand & Cement, etc... Answers on a postcard please..."

I've seen a few that look like they've been assembled with sand and cement  ;D but you may need planning permission for that  ;D ;D

It's a nice step when you get everything clean and ready to go together,  sounds like good progress.

Offline Nurse Julie

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Re: 1975 400/4 project
« Reply #74 on: June 11, 2019, 08:56:51 AM »
Hondabond. But, I think any of them, yambond, suzukibond etc are all Threebond just in different tubes. Avoid white bathroom sealant, it makes such a mess 😀😀😁😀
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new