Author Topic: advice needed  (Read 1065 times)

Offline mtrhead

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advice needed
« on: August 22, 2018, 04:18:45 PM »
Folks,
running at a glacial pace I'm finally getting round to attempting a top end rebuild on my (in pieces) CB550F2, the bike had been shed bound and unloved since 1982 when I picked it up in 2015! After battling with getting the rocker cover off and having to drill four of the screw head out I'm faced with the following dilemma and would appreciate the collective wisdom of you lovely experts :

So the bike was bought with a "locked" engine. Based on the sump contents I think its a case of stuck rings in the bores rather than a catastrophic failure. Having tried everything to turn it over (other than the electric start) I gave up and figured I'd need to at least strip the top end. Now I'm there of course I've got the inevitable issue that I can't get at the cam sprocket bolts to undo them and have no chance to rotate them. I've tried a ground down spanner but to no avail and I'm in danger of rounding off the bolt heads. If I'm understanding the situation I have the following options, none of which seem ideal to me:

1) Attempt to have another go at getting the engine to turn, possibly giving it a go with the electric start so I can rotate the cam and get at the bolts. I'm worried that might do a lot more damage to the bores if the rings are rusted and not going to budge at all.

2) Cut the cam chain and buy a split chain, then try and thread post to end rebuild so as to avoid having to split the crankcase (I wasn't intending on touching the crankcase unless I needed too). The David Silver cam chains look like they are endless and I'm sure I read in a few places that running a split cam chain with a link is not idea (are they even available?)

3) Cut the cam chain, man up and go for a full crankcase split and rebuild etc using a replacement endless cam chain

Any ideas or pearls of wisdom? your thoughts and experiences would be appreciated, anyone local to me in Bucks who fancies a good laugh watching a complete engine novice digging himself a very deep hole is also welcome :)

Alan

Offline Nurse Julie

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Re: advice needed
« Reply #1 on: August 22, 2018, 04:31:03 PM »
Have you tried turning the engine over with a big spanner on the end of the crank? You can get a lot of leverage that way but, depending on why the engine is seized, this may still not work.
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Online K2-K6

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Re: advice needed
« Reply #2 on: August 22, 2018, 04:44:06 PM »
I'd be inclined to use a continuous camchain as a long term plan,  so if you cut it then almost certainly committed to strip it for best future.  That really puts you in that position.

To turn it you may get more success by removing the alternator cover and using a big strap wrench directly on the rotor as it should give you the leverage to rock the crank back and forth to move them. Presume you've put lubricant down the bores to attempt to assist already?

If you go via the cutting camchain/remove the head route, you've still got to get the barrels off the stuck pistons so worth trying to move first as it's much harder to do that with the barrels unsecured.

I'm not that far from you and can offer to assist if any use.

Offline sye

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Re: advice needed
« Reply #3 on: August 22, 2018, 04:59:20 PM »
The old school way was to put diesel in the bore and leave it till it soaked through.

Offline Seabeowner

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Re: advice needed
« Reply #4 on: August 22, 2018, 06:03:58 PM »
ATF/ acetone 50/50 seems most recommended to free bores. Have you tried this? As said, use alternator side to turn. Unless you free it you still have to get the block off after removing the head. Presume you were going to pound it with a block of wood or the like.
It's a 40+year old bike, with probably more than a few miles on it. It could probably do with a new primary chain and cush rubbers in the primary drive. It's not a difficult job if I've done a few. No special tools needed. Just the expense of gaskets/seals etc. If you're already looking at rebore/cam chain/tensioner rubber/top end bits. You're already in deep.
I'm only 20 miles away, but no expert, despite what it says here! Away to N Wales. But can assist in in a couple of weeks. Just looked, you first posted 2015, so maybe no rush.

Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange
1978  CB550K     Excel Black

Offline Bryanj

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Re: advice needed
« Reply #5 on: August 22, 2018, 06:10:31 PM »
Stood that long it will need all the seals changed so a full strip down is on the cards therefore split the chain then remove the cam before trying to turn from the generator end NOT the points end after filling the bores via the plug holes with whichever brew you choose

Offline mtrhead

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Re: advice needed
« Reply #6 on: August 23, 2018, 10:30:43 AM »
Thanks all for the advice folks!
As you highlighted Seabeowner I'm not exactly in a hurry :)  so  I'm off to get some ATF/Acetone as I figure I've got nothing to lose to try another marinading session with a different sauce.
I have plenty of other fun including presumably finding a local spark erosion expert to get the remaining valve cover studs off as they don't appear to be at all frightened by my mole wrench. This engine is definitely fighting me all the way.
Seabeowner..thanks for the offer, I might well ping you at some point down the road perhaps just to pass judgement on the various parts as I manage to extract them. This is my first engine strip so I don't have a seasoned eye when it comes to spotting potential problems

Offline matthewmosse

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Re: advice needed
« Reply #7 on: August 23, 2018, 08:19:44 PM »
Worth trying to build up snapped off fasteners with weld to get a better grip with the mole grips before spending out on spark erosion. Often the heat will free things off. Drilling bolts out of the alloy can be tried but only for the brave. When you get it right, pulling a spiral of steel thread from the alloy is very satisfying, but normally it's more a case of the hole ends up as a mauled oval with half the bit still in there. Depends on your skill expirience and luck. Getting stuck pistons out of the bore can be fun, whip the head off, bash with a lump of wood between the piston and the hammer. I'd cut the camchain, it's the cheapest component to replace, stripping the bottom end is worth doing once you are dealing with as much as you are in any case, you may well be finding stuck clutch plates along the way, better to resolve that now, who knows what other joys may reside best rule it all out with a full strip down and rebuild as doing half the engine would be a false economy if it all needs to come appart again with new gaskets required if the reason the bike was parked up was a fault further in. With really badly stuck pistons in a rusty bore I once had to resort to filling the bores with old petrol, diesel and oil, putting the whole lot in an old wheelbarrow and throwing a match in on a hot day, it did eventually get the pistons out in 1 piece. That kind of brutality was the result of the plugs being left out of the engine and the engine living outside.
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Offline paulbaker1954

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Re: advice needed
« Reply #8 on: August 25, 2018, 08:19:21 AM »
I can only recount my experiences

My 500 four came from US and was seized.

 I tried every witches  brew known to man I think and all to no avail and ended up cutting the chain to get the head off.

As to the pistons I found if you split the cases etc you can just get the big end bolts off and then pull the jugs off with the pistons and rods still on. This way you are dealing with freeing one piston at a time which is much easier if they are really tight. Mine we so tight I ended up having them pressed out in a machine shop. As to why they were so tight I never figured that out as the bores were perfect original spec and only needed honing.

As to chain I ended up using a split one from DS for long and complicated reasons due to a mistake I made on the rebuild and it has been fine. Many many folks do a chain replacement this way on a wide range of bikes with no problems. Of course endless always best but IMO splits are ok.

If I were you I would take the opportunity to do a full strip and check as others have suggested while you are in there in which case obviously go endless chain.
 
« Last Edit: August 25, 2018, 05:45:10 PM by paulbaker1954 »
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Offline SteveW

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Re: advice needed
« Reply #9 on: August 26, 2018, 04:30:50 PM »
Where in Bucks are you?
Im just by junction 5 M40 if you need a hand.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline mtrhead

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Re: advice needed
« Reply #10 on: August 29, 2018, 12:52:54 PM »
Thanks for all the further advice folks it is appreciated.
I thought I'd just report back in case it is of use to others. After glaring at the engine for a long time in a desperate attempt to make it back down I realised the crank bolts were just about at the horizontal. Sacrificing a spare 10mm spanner I ground it down so I could slide it into the gap and managed to loosen off one bolt.  I'm not sure if I was just lucky but that gave enough wobble in the crank to actually get both bolts off and the cam out.
All points well understood about the need to go further and do a proper job on the rebuild. I've got the ATF/Acetone marinade sauce going, will probably leave it a week or so just in case it does something.
SteveW...I'm mid way between Wycombe and Aylesbury, if you fancied a cuppa and a laugh at my misfortune :)

Offline SteveW

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Re: advice needed
« Reply #11 on: September 06, 2018, 04:06:07 PM »
Sent you a PM
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline Colonial-Clive (yindi)

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Re: advice needed
« Reply #12 on: September 07, 2018, 03:46:34 PM »
Hi, I had rusted in pistons after taking barrels of with pistons I filled each on with brick cleaner (hydrochloic acid) nasty I know left 24hrs drained of and with a wood drift and lump hammer tapped out offending piston.

 

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