Author Topic: Engine teardown and inspection  (Read 8071 times)

Offline cantarauk

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Engine teardown and inspection
« on: October 07, 2016, 09:19:42 AM »
Hi,

I recently purchased a '72 CB500 which was a bit rough around the edges to say the least with the intention of rebuilding this as a Cafe style racer. I have been taking my time with the stripping down of the bike and am now at the point where I am taking the engine apart which is a new skill in itself.

I have read that camshaft bearing surfaces should be inspected and should be smooth and shiny and if there is excessive wear it or it is scratched it should be replaced. My question here is what warrants excessive wear/scratches as I have seen as bad surfaces on posts where used have said this should be fine. 

I have attached some images and would appreciate the professional opinion of the community.

There will be more questions the deeper down the rabbit hole I get.







Glenn
« Last Edit: October 07, 2020, 08:37:30 PM by cantarauk »

Offline Chris400F

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Re: Engine teardown and inspection
« Reply #1 on: October 07, 2016, 09:31:19 AM »
I don't think I would be able to comment usefully anyway but can't see the images so suspect others won't be able to either.
Can you check they are visible? Are they perhaps hosted somewhere not publicly accessible?
« Last Edit: October 07, 2016, 09:32:59 AM by Chris400F »

Offline Oddjob

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Re: Engine teardown and inspection
« Reply #2 on: October 07, 2016, 10:15:05 AM »
I can see them and they ain't pretty. Unfortunately there all apear to be of the 2 bearing surfaces next to the camchain tunnel, none of the 2 end journals. Red hermetite everywhere (oh dear) camchain tunnel is badly marked with what appears to be where the chain has broken at some time. Journals are very poor, not good at all, looks like something has gone round at some point as the oil spreader opening is peened over on the edge.
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Offline AshimotoK0

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Re: Engine teardown and inspection
« Reply #3 on: October 07, 2016, 11:06:15 AM »
Agree with Oddjob. What does the mating cam cover & camshaft look like ? I think there is a CB magazine article on the 400/4 project bike  setup which had been fitted with NOS Villiers engine shells, I think previously carried out  by Dixon Racing ( they had fitted a new cam cover and half bearing shell arrangement  in the head). This requires precision engineering though.

Your best bet is either a replacement from DK or Jap2wheelz (Frank)  in Germany though.  Both have a decent reputation and good returns policy. Or perhaps someone on here has a decent spare to sell you.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline AshimotoK0

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Re: Engine teardown and inspection
« Reply #4 on: October 07, 2016, 12:22:20 PM »
Further to last post of mine here is the Dixon Racing conversion on the CB bike
Go this below back from Rick Parkington of Classic Bike Magazine regarding the cam bearing shells fitted to the CB400F project bike they are building. Interesting stuff !!

Cheers ... AshD

-------------------------------------------------------------
Hi Ash,  Received your message to David Silver via a rather circuitous route! Afraid I can't offer much more information at present  largely because the engine is sitting inverted on its head while I  assemble the bottom end! I will by all means take a closer look when it's right way up again. Since the cam cover has no shells fitted, the cam diameter must still be standard and that means that if these are Kawasaki shells, it must be a model whose cam is the same diameter as a 400/4. My issue was that as a machining job it isn't one I'd like to undertake because the head design prevents starting from one end and boring straight through; it would be tricky to get right starting with an already worn head and it wouldn't have to be far out to seize. I'm guessing there's more slack on the fit than there was on the DOHC motors where the cam caps were not avaailable separately and disaster followed mixing them up... The cam cover is away for chrome stripping and polishing just now but I'm looking forward to plastigauging the fit of the cam when it returns. I can see it would be a big help to SOHC owners to find out how this was done (in my bike shop days I used to have a black museum of gruesome SOHC Honda cams!) but I have a feeling finding the shells may only be half the answer, it's a pity it looks like it was done before my mate bought the bike Cheers Rick

Hi Ash,
OK got bit more info now. The bearing shells in the head are not Z1. I popped one out and the number on the back is G (in a square) S8919M. The stamping looked similar to that on Triumph shells, so assuming it was a Glacier bearing I tried Googling the number but no result.Giving up on the Internet I did what I should have done first and checked my 1968 Glacier catalogue. Turns out they are from a Villiers industrial engine. The set number was B 1042 S and the engine is a Villiers Mk12 1.5hp, 120cc. The shells in the head are minus tens; turns out the Villiers standard shaft diameter is 0.874", I measured the cam at 0.864", so using -0.010" shells will make the fit right for the Honda cam. I suspect these bearings will be hard to obtain now but you never know.Speaking to someone yesterday who reckoned that back in the day Dixon Racing used to do cylinder head bushing operations, thy supplied the Yoshi parts so that would make sense.Thanks for the invite to the forum; not sure I'd have much to contribute, I'm afraid this is the first four I've laid a spanner on. Work aside I avoid the computer - too much to do in the shed. I actually started a blog this year (www.rickparkington.co.uk) and am having trouble finding the time even to do that! But feel free to use this info and pics. Hope it proves helpful.
All the best Rick P



http://vintagemotorcyclepistons.co.uk/page/5




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« Last Edit: October 07, 2016, 12:24:20 PM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Trigger

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Re: Engine teardown and inspection
« Reply #5 on: October 07, 2016, 12:54:02 PM »
I also can't see any pictures.

Offline AshimotoK0

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Re: Engine teardown and inspection
« Reply #6 on: October 07, 2016, 01:40:47 PM »
I also can't see any pictures.

They are coming up OK for me Graham but here if you can't see 'em

https://www.dropbox.com/sh/axf4lyhra89zsi0/AAC2kGVjjiKQbDq8nRTavorFa?dl=0
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline clive

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Re: Engine teardown and inspection
« Reply #7 on: October 07, 2016, 01:45:13 PM »
i can,
cb500/4, 535 virago, sunny south yorkshire, apart from floods, earthquakes

Offline Nurse Julie

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Re: Engine teardown and inspection
« Reply #8 on: October 07, 2016, 02:11:28 PM »
I cant see the original pics either
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
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Offline AshimotoK0

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Re: Engine teardown and inspection
« Reply #9 on: October 07, 2016, 02:36:52 PM »
I cant see the original pics either

Feeling guilty about using up all of Steve's storage ... so off to make a site donation...HINT  ;)  Blaming Trigger & Julie  :D

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“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Oddjob

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Re: Engine teardown and inspection
« Reply #10 on: October 07, 2016, 10:43:01 PM »
500 heads and cam covers are pretty common, as are camshafts. Far cheaper to just buy good second hand ones. I'll have a look and see if I can help, I have loads of spare parts for 500 engines.
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Offline matthewmosse

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Re: Engine teardown and inspection
« Reply #11 on: October 08, 2016, 08:41:44 AM »
I have a head + top end off a cb500 that has been modified to run needle roller bearings, bought years ago off ebay, the seller didn't know who had done the conversion. I reacon the cb500 head and cover could be converted to allow for the cam bearing to be line bored down its length and sealing caps inserted at the assembly stage ( might be a bit involved given the need to seal up the cover with bolts holding it down being in the same place etc). On my kl250 I found a local shop willing to machine out the knackered head bearing surface and insert a phosphur bronze insert for the cam to run in, a much simpler prospect but surprisingly cost effective costing only £65 which was cheaper then any good cylinder heads off ebay in the 6 months I was looking.
I have a few worn heads if anyone wants to have a go at a modification, the guy who did my kl head was only willing to give it a try when he had 3 spares available so no loss if it didn't work, and then he modified the worst one.
Got a 500/4 with rust and a sidecar and loadsa bits. nice and original and been round the clock

Offline AshimotoK0

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Re: Engine teardown and inspection
« Reply #12 on: October 08, 2016, 10:28:40 AM »
500 heads and cam covers are pretty common, as are camshafts. Far cheaper to just buy good second hand ones. I'll have a look and see if I can help, I have loads of spare parts for 500 engines.

I fully agree Ken  but sooner or later we are going to run out plus what happens if the valves/ guides/fins/mating surfaces/threads are all fine or refurbed and you would like to keep the original head. By posting the alternative options on here then in years to come it may benefit someone, which to me is what these forums are all about IMHO. Taking bikes like the CB250/350K try finding a decent pair of used cam bearings ! Interesting that Dixon Racing would take all of that trouble in what I guess was 1980's , early 90's.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline cantarauk

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Re: Engine teardown and inspection
« Reply #13 on: October 08, 2016, 12:11:40 PM »
Hi all,

Thank you for the replies and advice so far. As mentioned I am all new to this but it all makes sense to me and I guess what I have currently needs either replacing or machining to make good. I am away for the weekend but when I get home I will fix the images so that all can see them and the also add additional images as requested. Thanks agin.matthewmosse where is your contact that machined you kl based? Or does anyone know a machinist up north (Yorkshire) who would undertake this ? £65 seems like a bargain to me


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Offline matthewmosse

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Re: Engine teardown and inspection
« Reply #14 on: October 08, 2016, 03:00:58 PM »
Mid Wales motox handled my kl engine rebuild and Matt who runs it outsourced the machining  - I think to a retired enginerr who does a bit to keep himself entertained. Normally I would think replacement would be cheapest for a worn / dammaged head, but since I last had to buy bits for a cb500, parts have kept creeping up so that is open to constant re evaluation, gone are the days of £50 complete engines that could simply be dropped in and run for the cb500 or 550. 
For myself I stockpile bits like worn cylinder heads for these bikes, at some point it may be viable to either get a batch machined or invest in the kit to re work them when good spares dry up. The rear brake hubs proved not too hard to repair, but after I figured that out and did a few for myself I found an engineer in Huddersfield doing them at such a bargin price I wouldn't be in a hurry to do another.
Got a 500/4 with rust and a sidecar and loadsa bits. nice and original and been round the clock

 

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