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Never take anything for granted

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philward:
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

Nurse Julie:
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.

SumpMagnet:
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.

philward:

--- Quote from: philward 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

--- End quote ---
Oh, I forgot - ALL the cylinder head to barrel seals missing (just head gasket)

Rob62:
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)

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