Author Topic: 550 top and bottom rebuild  (Read 285 times)

Offline Richie 550/4

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550 top and bottom rebuild
« on: February 09, 2020, 02:49:31 PM »
Hello all.

Sorry for disappearing on you all late last year. I have been flat out clearing my Callander ready to attack the rebuild.

I am pleased to report that I have now got my teeth well into the rebuild and thought it was time I gave you all an update on my progress so far.

Since my last posts, I have spent many an evening researching and violating parts and knowledge from friends and the beloved you tube.

I now have the crankcase split and have retrieved the cam chain guide which appears to have been the initial offending part that caused the cam chain to break in the first place. In 600 miles since the previous owner had done a “top end” rebuild. The cam chain had been orb completely through the guide face and then right through the steel backing, getting caught on the backing and subsequently breaking the chain. Lucky for me, as the engine had only been running for a short time under these conditions it has not done a huge amount of damage. The big end and main bearing are caked in steel particles from the guide and are no good, but this has not damaged the journals.

So. After this investigation, I have now a big long list of parts on the way for the rebuild. Luckily I only needed one pair of A bearings (the rare and elusive A bearing) my local engineer shop has measured the crank and has said a B bearing still brings me within clearance. 

I have had the top and bottom end vapour blasted and some of the covers, I’ve also made a couple of repairs to the bore fins and painted the block. Whilst in the bottom end I’ve found the reason for poor fifth gear selection. Worn main shift fork. I’ve sourced all new bearings apart from three which are no longer available and again, luckily. These three are still good in the original, so will be going back in along with a multitude of new parts. David Silver and CMSNL have both done very well out of me over the past few months.

I have spent hours cleaning up parts and polishing out some slight corrosion on some parts in the bottom end. It seems this bike may have been say for a while at some point in its life. A few parts like the shift drum had some minor pitting and the shift fork spindle. So out came the polishing paste’s and away I went.

So enough of my waffle. Here are some pics for your rainy days.

Offline SteveW

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Re: 550 top and bottom rebuild
« Reply #1 on: February 09, 2020, 06:25:15 PM »
Where about in Oxfordshire are you? I’m just over the border in Bucks, just on the M40 junction 5.
1974 CB550 K0
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1980 RD350LC

Offline Richie 550/4

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Re: 550 top and bottom rebuild
« Reply #2 on: February 09, 2020, 06:29:12 PM »
Botley. Oxford.

Where bouts in Bucks are ya?

Offline Bryanj

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Re: 550 top and bottom rebuild
« Reply #3 on: February 09, 2020, 08:21:24 PM »
If you got ALL the bits thats less than a day to a complete lump, or at least i could. Im in Gloucester by the way.
Got 2 spare selector drums on desk, same as 350 twin

Offline Trigger

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Re: 550 top and bottom rebuild
« Reply #4 on: February 10, 2020, 08:19:56 AM »
Nice looking cases.
I am not a fan of vapour blasting as last year alone I had 3 engines in that had destroyed themselves due to glass bead still in the oil ways. When cleaning out the oil ways there is one that most people miss. You have to remove the slugs on the sides of the head and clean out the oil way that feeds the cam journals and then make new slugs to cap  ;)

Offline Oddjob

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Re: 550 top and bottom rebuild
« Reply #5 on: February 10, 2020, 09:42:21 AM »
I have some black crank shells, I may be persuaded to part with 2.
Don't play stupid with me, I'm better at it

Offline SteveW

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Re: 550 top and bottom rebuild
« Reply #6 on: February 10, 2020, 12:01:09 PM »
Botley. Oxford.

Where bouts in Bucks are ya?

Stokenchurch
1974 CB550 K0
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1980 RD350LC

Offline Richie 550/4

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Re: 550 top and bottom rebuild
« Reply #7 on: February 10, 2020, 04:37:18 PM »
Hi all

Thanks for your advise members.

I agree Trigger. Very nerve wracking to think some media may be still lurking somewhere. Thanks for the heads up on the head plugs being a problem area to keep an eye on. Are we talking all 3 plugs per side of the head or just the central one on the Oil way?

Oddjob. I would be interested in taking a pair of black bearings off your hands if the offer still stands. I would feel more confident knowing the spot on size is down there. Let me know what you want for them.

Many thanks. I look forward to maybe meeting up with some of you guys this year. I take it there are members meetings organised?

Offline Richie 550/4

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Re: 550 top and bottom rebuild
« Reply #8 on: February 10, 2020, 04:43:24 PM »
Hi Trigger.

Do you have any suggestions on removing these plugs on the head? Is this a drilling out job or is there a clever way of removal? I take it from your mess these are not available for replacement and need to be machined?

Richard

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: 550 top and bottom rebuild
« Reply #9 on: February 10, 2020, 04:46:09 PM »
Yes, some of us are meeting up at the Classic Bike Day at Crich on 5th July. Always a great day out and free for us to get in if we arrive on one of our old Classic bikes.
Details on the link below.
http://www.sohc.co.uk/index.php/topic,20907.0.html
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 Trigger

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Re: 550 top and bottom rebuild
« Reply #10 on: February 10, 2020, 07:31:55 PM »
Hi Trigger.

Do you have any suggestions on removing these plugs on the head? Is this a drilling out job or is there a clever way of removal? I take it from your mess these are not available for replacement and need to be machined?

Richard

It is only the centre slug that needs to be removed. Drill, insert a tap and connect a slide hammer to pull it out. You need a lathe to make new ones  ;)

Offline Richie 550/4

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Re: 550 top and bottom rebuild
« Reply #11 on: February 11, 2020, 08:51:01 AM »
Hi Trigger

Thanks for the valuable advise. I owe you a drink or two

Offline Trigger

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Re: 550 top and bottom rebuild
« Reply #12 on: February 11, 2020, 12:22:03 PM »
Hi Trigger
 
Thanks for the valuable advise. I owe you a drink or two


You won't see that on a YouTube vid  :o  ;)

Offline Richie 550/4

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Re: 550 top and bottom rebuild
« Reply #13 on: Today at 07:22:55 PM »
Hi all.

Just a quick update on my progress with the rebuild.

So. I have the crankcase back together for the final fit. Just the primary shaft to fit and oil pump. I’ve been through the gears and all seems well.

Attached a few pics

Many thanks to those who have been so helpful coming forward with your advise and experience.

Richard

Offline Richie 550/4

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Re: 550 top and bottom rebuild
« Reply #14 on: Today at 07:26:50 PM »
Sad news!

I was picking up some parts from a local custom builder today, he had recently had a workshop fire and one of the casualties was a recently fully rebuilt CB750 early 70’s

A very sad sight indeed.

Hope he can salvage her?

R

 

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