What is a realistic lifespan for a CB500/550 camchain?

[Bryanj]

Delta, the only way an owner would know about the primary chain is if they know exactly where to feel with the sump off OR where to look when the cases are split for some other reason. I have just had the sump off a 50000 mile engine and the wear is significant with a feelably loose chain.

[Trigger]

Same as they didnt put a new chain in the cx500 tensioner mod kit so you ended up doing them again at about 30000

I was always surprised how the CX chain stretched so fast being a HI-Vo and short at 78 links 

[Bryanj]

Well ive been using it for years but then i did sail with chinese crew who used englishish

[K2-K6]

Is "Feelably" actually a word?

wasn't that one of the tellitubbies?  Or that's what they called him behind his back, although not proven through legal process 

[K2-K6]

"In my archives there's also an article about a Dutch teacher who back then has bought his CB500 new and with just regular maintenance in 20 years, using it as a daily rider to go to work, winter and summer has done 220.000 kms without the block ever been opened. He confessed he seldomly went over 6000 rpm"

This illustrates that mileage as an absolute basis for judging the chain life has potentially large error.  The only consistent accurate way at technical level is to count crankshaft revolutions.  Chain life at average of 4,500rpm v the same at 7,500rpm will clearly reach the same wear point at very different mileage totals.

There doesn't appear to be any problems with "tensioner" units in quality or design.  It's secondary, as if the chain didn't wear, then the adjustment likewise wouldn't have to move.

Any improvements would come from preventing the chain from wearing at the same rate,  that would be either material specifically in the chain bearings or a change in lubricant that would better support the chain bearings.

[robvangulik]

This illustrates that mileage as an absolute basis for judging the chain life has potentially large error.  The only consistent accurate way at technical level is to count crankshaft revolutions.  Chain life at average of 4,500rpm v the same at 7,500rpm will clearly reach the same wear point at very different mileage totals.

That doesn't work either, when riding in the same gear your distance per revolution will be (approx) be the same at high and low revs, just in a shorter time frame

[K2-K6]

You're right robvangulik,  but it's because I've used rpm to describe engine revs of which the "m" is time component.

The correct technical / grammatical description to describe the chain's life would be engine revs in total accumulation,  just that we reference them as "rpm" because our usual indicator,  the tachometer says that.

To clarify,  chain life should be consistent and measurable to reasonable accuracy in total cycles or accumulated crankshaft revolutions.

[Trigger]

I never believe any customer who states that they change there oil regularly or that the engine has never been apart or that it has only done 20.000 miles because that is what the clock says. As i have stripped engines down to find non OEM cam chains, non OEM internal bolts and washer, non OEM cam blades and a load more.

Trigger always finds the truth when I am inside the motor 

 

[AshimotoK0]

The original CB250 in early 1968 had a hydraulic cam chain tensioner pressurised by the oil pump pressure. By the sounds of it ..literally... it was a complete distater and Honda quickly  issued a modified spring loaded replacement with locking bolt... of a similar desing to what they used on the up and coming CB750. I had never seen one of the originals up until a few years ago until  I bought two early CB250K0's from the estate of an old guy. They both still had their original hydraulic tensioners fitted as they had never been recalled (they had been off the road since the early 1970's). One had only done a genuine 4.5k miles and the other 6.5k miles. On both engines, when stripped, the cam sprockets and the chain in particular were worn ...which brings home to me that  correct cam chain tension is critical to the life of the chain.

Talking to a couple of guys on FB who rode these bike when new..one of them was the workshop manager at Freddie Friths in Lincoln, they reckoned you had to ride the first few minutes with the cam chain rattling, which then went away.

Also the Freddie Frith bloke told me he was in the shop one day when Dick Emery came in to to test ride the 1st CB750 they got in, as he was in Panto at Cleethorpes. Dick then went back home south and bought one (BYU 764H) from Tippets of Surbiton. Freddie Frith  took a photo of him on it but sadly, the chap can't find it.

[K2-K6]

In parallel to you Ken, one of these has gone live on the USA site but not yet a longer term view.

http://forums.sohc4.net/index.php/topic,182030.0.html

It seems to make it quieter from initial reports as he's running it with a worn chain, sounds severely worn too! So effective from that point of view and may be to keep the chain from machining the case casting internally. 

I'd be more concerned that he feels his problems have gone away though with the chain that worn, and could understand why you changed them if ever the cases were split (seems daft not to) also interesting that the Benelli guy is looking at it too as it's a straightforward copy of the Honda in that regard.

Edit;- it's these words from that thread that alarm me "Following an hour ride and some aggressive testing, the part performed perfectly.
Prior to the install, I had excessive chain slap that resulted in a rough/noisy idle and metal flakes in the oil pan. After the install, the idle is smoother and there is no chain slap in the lower end. Overall, this was well worth the effort."

If ever one needs changing 

[Trigger]

There is no point having a worn chain that is quiet. The more it stretches the more the teeth on the crank get worn and the teeth on the primary drive. Another false economy when, you think how much a crank and new shells to match cost.

[AshimotoK0]

The aftermarket chains are crap that Sliver sells as a OEM replacement and the Honda ones are £££

That's worth noting everyone ... it's bad that they are being sold as OEM and not as good. I got mine from Yamiya in Honda branded packing so hopefully it is OK.

[K2-K6]

Thanks to you all!

... Which oil do you use and what change intervals?

Bike has been maintained well. Over the years I have used various oils. At the time it was Castrol GTX2 ofcourse. Last ten years it has been Castrol High Mileage and I must say I'm very pleased with it. It keeps everything clean and helps rubber seals live longer. I prefer 15W-40, because I won't operate the bike at lower temperatures than say 15^oC. In long vacations I saw no problem doing 5000km before an oil change. Long rides and ideal circumstances. One day in Spain when I changed the oil - I had to renew some oil pump O-rings - the mechanic in who's workshop I did this, was surprised I didn't pour the collected oil back in again. I told him I had been riding 4-5000 km and it was time for an oil change. He kneeled, dipped his finger in it, rubbed it between thumb and finger, smelled it and concluded: "como nuevo" and asked me if he could have it for his Laverda. Below a pic of what the oil screen looked like after some 50.000 kms. Mind you, before cleaning! Also the oil pan was super clean. Never seen any sludge. Decades ago I found a chafe (is that the word?) of aluminium in the oilfilter housing or oil pan (forgot which). Could well have been from the drive chain eating in the crankcase. This was some 30 years ago.
Alas! In the meanwhile there's a new development. Let me look for the link.

The route taken above intrigues me, to which I'd like to add my views.

Agree that current oils show remarkably clean condition during service life. To me this primarily indicates low oxidation,  tolerance of the heat it experiences (resistance to burning into black carbon deposits) but also as I understand it,  will be deteriorated specifically in it's film strength which is unseen to visual examination. 
I too use the smell test,  but if you are doing this you have to have a direct comparator (new oil) to give yourself a baseline.  I think if you do this it will be more clear just how much of unburnt combustion byproducts it contains.

I'm not sure that the service change intervals can be arbitrarily changed to double or triple the mileage because of the reasoning layed out in above paragraph.
These engines routinely run richer than the ideal fuel burn required (they're not alone in that aspect as all engines from that era do) but it's this consideration that serms to have made the most difference in oil servicing/lifing of newer and current production vehicles more than anything I've seen.
Basically it would have to run more efficiently fuelling wise to  change the oil's service period irrespective of what the oil looks like. I feel there's a way to move these more in that direction safely that could help.

The "high mileage" oil choice is something I'm seeing in a different perspective too.  Oil companies are very marginal in how they describe an oil's intent within markets.  To me everything about that description says helping to nurse an old and potentially worn engine over it's final mileage,  as opposed to an oil that will offer increased protection over longer mileage.  There's a subtle difference,  I agree,  but their terminology for what i feel you've intended to do is "long life " oil.  There's a more useful choice within the castrol range that specifically offers better protection of highly loaded components.

It's interesting that  most (maybe all) generally available oils will have no connection whatsover with the engines of this type,  we are really on our own in decisions like this.  Their descriptions don't help.

Also,  many of the oils by default have reduced metal to metal contact (exactly what's happening in a chain bearing) protection as they are favouring emissions equipment lifing as part of their bulk marketing strategy.  I believe this is mostly a severe reduction, or elimination of zddp content to best preserve catalysts within vehicles they now consider old and "high mileage " this being the opposite of these (honda sohc era)  engine's needs. Led by legislation originating in California,  the industry is aware of how the current oils compromise valve system and materials traditionally used in engines,  but feel the environmental benefits outway any concerns about older engines longevity.  Newer engines are being specced metallurgically to work in this way to keep durability with oil formulations available currently.

Edit;- to add  https://www.theoillab.co.uk/product-category/oil-testing/engine/ link that illustrates what the oil can be tested for. Expensive warranty claims are sometimes subject to this type of service to establish if the correct oil has been used, plus it's condition at point of failure.

[Bryanj]

Can anybody explain why a new Kawaski primary one which is the same from Fowlers is almost 2/3 cheaper at £44?

[Bryanj]

I looked at an ebay reference that gave several numbers one being a Kawasaki number so copied it into google. I will see if i can find it again.