Author Topic: Never take anything for granted  (Read 351 times)

Offline philward

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Never take anything for granted
« on: March 12, 2019, 05:30:22 PM »
Just started the new K6 Cafe racer project I bought over 15 months ago. This has had a lot of work done on it already - powder coating, all cases polished professionally, carbs rebuild, new tyres, Borrani rims, new forks, new SS downpipes (on ebay at the moment) huge Mechemex alloy swing arm (going on ebay at some time), etc. Previous owner advised he had bought it as was but was told it was running well before being stripped. (he wasn't very mechanically minded so project was too much for him).
Anyway, I was going to re-wire with new parts and then start up to appraise what it sounded like. When fitting the coils, I noticed the front M6 cyl head bolt missing - so loosened the rocked cover so I could drop the M6 bolt in. Had a quick look inside and spotted a few rusty valve springs! I have never done a 750 project without a full engine rebuild (4 of them now) and this experience emphasises why I have!
So, engine out and first thing I find is 4 bolts missing from cam carrier and snapped cam bearing bolt loosely placed in the cap! (plus the 4 rusted valve springs). So that alone would have caused a catastrophic engine failure - so glad I spotted that missing M6 bolt.
The engine is now completely stripped and although cam chain/tensioner wheels knackered, luckily it looks like the bottom end appears not to have been apart so nobody's done any bodge damage to that area - mains, big ends, gearbox bearings, bores all good.
So, new cam and primary chains, tensioners,oil pump recon and rings (plus seals, gaskets) should see it to the required standard - not cheap but a lot cheaper than a blown engine. Phew... lucky escape!
There's a moral there somewhere for anyone on the forum who's on with a project at the moment were they are assuming a cosmetically good engine is ok - is it worth the chance?
Phil
Current Bikes:-
Kawasaki ZZR1100D3
Honda CB750K2
Honda CR750 Replica
Honda CB750K6 Cafe Racer Project
Kawasaki ZZR250 (1990)

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: Never take anything for granted
« Reply #1 on: March 12, 2019, 05:42:18 PM »
Oh dear Phil, that is a bummer. But, as you point out and you are right in doing so, you can never, ever tell what state the inside of these engines are in until you take them apart. Unfortunately there are so many bullshitters out there (intentional or unintentional), that nothing can be trusted. More so with the CB750/4 engine, where you can't just lift the lid and have a look see.
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 SumpMagnet

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Re: Never take anything for granted
« Reply #2 on: March 12, 2019, 05:51:46 PM »
very true...which is why my engine is in hundreds of pieces in boxes and bags....

Most of it was fine...but there are always things that lurk in the bowels....

In my case, busted clutch centre shaft, and knackered final drive bearings. Would probably have run just fine....until I started using it.
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline philward

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Re: Never take anything for granted
« Reply #3 on: March 12, 2019, 06:00:27 PM »
Just started the new K6 Cafe racer project I bought over 15 months ago. This has had a lot of work done on it already - powder coating, all cases polished professionally, carbs rebuild, new tyres, Borrani rims, new forks, new SS downpipes (on ebay at the moment) huge Mechemex alloy swing arm (going on ebay at some time), etc. Previous owner advised he had bought it as was but was told it was running well before being stripped. (he wasn't very mechanically minded so project was too much for him).
Anyway, I was going to re-wire with new parts and then start up to appraise what it sounded like. When fitting the coils, I noticed the front M6 cyl head bolt missing - so loosened the rocked cover so I could drop the M6 bolt in. Had a quick look inside and spotted a few rusty valve springs! I have never done a 750 project without a full engine rebuild (4 of them now) and this experience emphasises why I have!
So, engine out and first thing I find is 4 bolts missing from cam carrier and snapped cam bearing bolt loosely placed in the cap! (plus the 4 rusted valve springs). So that alone would have caused a catastrophic engine failure - so glad I spotted that missing M6 bolt.
The engine is now completely stripped and although cam chain/tensioner wheels knackered, luckily it looks like the bottom end appears not to have been apart so nobody's done any bodge damage to that area - mains, big ends, gearbox bearings, bores all good.
So, new cam and primary chains, tensioners,oil pump recon and rings (plus seals, gaskets) should see it to the required standard - not cheap but a lot cheaper than a blown engine. Phew... lucky escape!
There's a moral there somewhere for anyone on the forum who's on with a project at the moment were they are assuming a cosmetically good engine is ok - is it worth the chance?
Phil
Oh, I forgot - ALL the cylinder head to barrel seals missing (just head gasket)
Current Bikes:-
Kawasaki ZZR1100D3
Honda CB750K2
Honda CR750 Replica
Honda CB750K6 Cafe Racer Project
Kawasaki ZZR250 (1990)

Offline Rob62

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Re: Never take anything for granted
« Reply #4 on: March 12, 2019, 08:51:15 PM »
Sounds like those issues are due to poor engine building, not age related... If these engines have been left alone and not messed about with, they can be very reliable despite being old. It doesn’t follow that every old engine will need a full rebuild... but you do need to have a good initial examination as you did.. looks like you avoided a big problem. 8)

Offline philward

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Re: Never take anything for granted
« Reply #5 on: March 12, 2019, 09:07:43 PM »
Absolutely Rob - apart from the worn chains/tensioners, its all about the numpty previous engine builder. The issue for us old bike rebuilders is knowing whether an engine has been messed with by a numpty!
Current Bikes:-
Kawasaki ZZR1100D3
Honda CB750K2
Honda CR750 Replica
Honda CB750K6 Cafe Racer Project
Kawasaki ZZR250 (1990)

Offline Rob62

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Re: Never take anything for granted
« Reply #6 on: March 12, 2019, 09:40:05 PM »
........ The issue for us old bike rebuilders is knowing whether an engine has been messed with by a numpty!
Hehe...so true Phil  :o

Offline SumpMagnet

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Re: Never take anything for granted
« Reply #7 on: March 12, 2019, 11:59:56 PM »
People make mistakes building engines..... but I have never understood how people can completely miss out parts. Surely they must have wondered why there were bits left over....

Also...when things are broken...like a snapped bolt...just putting it back in so it looks OK? That's not making a mistake... that's something else entirely
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Mr_Sheene

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Re: Never take anything for granted
« Reply #8 on: March 14, 2019, 12:23:25 PM »
Unless you know what work was done and by whom, you run a serious risk with any engine. Some overestimate their abilities but many are just plain crooked. I'm being clever after the event. Julie can testify how close I came to catastrophe and some of the damage must have been done by the seller showing me how easily it started. Funny how it didn't start when I got it home! Cynical caution saved me and 'Trigger' fixed it but the advice from well meaning friends was 'run it and give it time to bed in'. If I had it would have 'blown' and the seller would be in a position to say that he didn't know how I'd treated it. Not his problem! Caveat Emptor.

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: Never take anything for granted
« Reply #9 on: March 14, 2019, 12:59:15 PM »
Indeed Phil, your engine was in a terrible, terrible state, one of the worse we have had through here for major damage to almost every internal component and positively dangerous, just by the seller starting it that once, as you know.  I don't know what handbook the seller was using when he worked on that engine but all he achieved was total destruction of what should have been a nice running safe engine.
« Last Edit: March 14, 2019, 01:03:57 PM by Nurse Julie »
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 Seamus

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Re: Never take anything for granted
« Reply #10 on: March 16, 2019, 09:15:12 AM »
Restored a K1 once, it was bought as being fully done and working. Leaked a little bit of oil from the drive gear. Turnrd out that the chain had been through the cases and it was repaired with epoxy resin. Lovely.
Lucky at the time as my bro in law worked with an aircraft approved welder. Did a great job