camchain tensioner

[DomP]

Would it be fair to say the 500/550 camchain adjuster is the weak point in terms of design on these engines?  When I rebuilt my engine i now wish I'd replaced the whole assembly, the slot in the adjuster screw is a bit chewed up making it hard to hold still while tightening the 10mm nut.

[Bryanj]

Not really, its fine till its abused by somebody trying to remove any slack by turning the screwdriver slot.
If used solely as the manual says there are no problems.
The 500 primary chain does eat into the main oil gallery in lower crankcase but the 550 was a slightly different casting.

The most common fault on 500 was centre selector wear and on the 550 one gear can shear the dogs off but cant remember which

[deltarider]

Not really, its fine till its abused by somebody trying to remove any slack by turning the screwdriver slot.
If used solely as the manual says there are no problems.
[...]

IMO, it's by far the shittiest part on the CB500/550s. What Bryanj doesn't tell, is that the mechanics at Honda dealers in Europe have been instructed by their resp importers on how to perform the adjustment best. That differed from what a customer reads in the manual. As it is sooo easy to damage the camchain tensioner assembly - it was designed far too fragile - Honda had done better not to give any instructions in the Owner's Manual on this, but to advise owners to have it done by a dealer.

[Seabeowner]

Whatever method you use Bryan's method. your Euro method or the manual, as long as you don't wreck the screw head the worst you get is maybe a slightly looser cam chain, not the end of the world.

[bigmockuk]

hi guys,im not long finished building the engine back up,decided to strip it back down and fit rubbers to camchain tensioner,but no joy! rattle is still there,the camchain guide is fine and i dont believe the chain is worn,after fitting chain to the sprocket and sprocket to camshaft i loosen adjuster nut when no1 cylinder is on commpression stroke and advance spring is in alignment with timing notch then the tension on the chain seems fine,nothing loose.the only thing i have`nt checked on the top end is to see if there was a broken inner valve spring which i doubt.i`ll  upload a short video i took of the noise to youtube and post the link,again,cheers for allyour input on this.

[bigmockuk]

video link https://youtube.com/shorts/bnGOP-TrCN4

[Nurse Julie]

A few strange noises going on there. It sounds 'tappety', almost like a chipped tappet or misaligned or something that's not allowing it hit the top of the valve stem square on.

[bigmockuk]

nursejulie thats my thoughts too,i was so sure it sounded like a very loose tappet,or damaged shaft,another member wrote about a 400cc having side movement at the tappets even though that bike has springs to help prevent sideways movement,up close,some of mine look nicely rounded off but others have slight imperfections,almost pitted,not sure if that could cause it.my tappets have a lot of sideways movement im thinking putting shims in there might help.im still positive its related to the rocker gear somehow.

[Murf]

Well the engine is a bit noisy and has some rattling, it’s already been said but are you sure that the exhaust gaskets are not blowing a bit or even a bit of a blow on the cylinder head gasket.

At the moment we are all chasing shadows, so I feel you need to go back and systematically go through the problem. Every part of the engine has a specification  with a + and - tolerance, which is listed in workshop manual.  So you need to check the components which might create a top end rattle are within tolerance.  For example side float on the rockers has a tolerance listed, check them with a feeler gauge, if they are in tolerance then that’s not the problem.  If they need shimming then the difference between the listed specs and the actual gap will be the size of shim you need, you can’t make them tighter than the specified end float, or they will wear away at the head. You need to keep the rocker central to the valve stem, so need to know which side to put the shim, or do you need a half width shim on each side? 

What I would say is strip the top end then go through all the components:- bore wear, piston wear, piston ring wear, small end wear, big end wear,  all components related to camchain tensioner, cam lobe wear, cam bearing wear, engine valves, valve spring length, rocker shaft wear, rocker end float, worn or mushroomed tappits. Rebuild carefully , check engine timing, check ignition timing, put new spark plugs in. New gaskets and seals. Balance carbs. 

Then hopefully post video of beautiful sweet running engine 😄.
Well that should work but there ain’t no certainties with old engines.
BTW I am certain I will have missed something important from that list so please add.

[bigmockuk]

Cheers for that Murf,its certainly in depth,and gives food for thought,im gonna step away for a few days n get some fresh perspective on things,i`ve got two bolts de-threaded now inside the top breather cover probably due to amount of times i`ve had it apart in last few weeks,so i`ll use thread inserts that i have to sort them.the bike is 48 year old but lay in a garage for 35 year so was only really on the road for like 13 year and covered around 25,000 miles,i would`nt expect to see any real wear n tear,it was running fine until recently then this noise developed so more sudden than gradual,it does have a loud clutch basket that i need to look into so the way ahead is to strip top half completely down n take measurements and renew all gaskets,do you know off hand where i could get a hold of shims thin enough i could use on side rockers? i`ll post back once i`ve had time to go through things and determine whats wrong and like you say,hopefully have it running sweet again soon 

[Bryanj]

Sitting for that long can frequently cause rust spots in the bores leading to bad rings and bad piston fit

[Murf]

Well after saying there were Specifications for everything, I can’t find any specs for rocker arm end float 🙁. Anyway I have had a good look at a rocker box I am going to use to replace the knackered one on my K1 550, it is the later type with the pinned rocker shafts like the one you should have.

I have checked the rocker end float:- rockers for  2 and 3 cylinders they range between  .012” to .017”

For 1 and 4 cylinders they are .012”
All measurements are in thousands of an inch.

I have listed them as above because the casting in the rocker box for 1 and 4 cylinders is different to that for 2 and 3
1 and 4 have a step in the casting as shown in the photo, so clearances have to be taken on the stepped out area.

I will use this head on my engine and feel it is ok, am I right, I don’t know really, maybe someone could check the clearance on the NOS rocker box they have in their parts sash 😁.

[bigmockuk]

i should probably have honed the cylinders,i just gave them a good visual check,oiled them up and rebuilt the engine,as to end float on the arms,murf, i can certainly check n see what their at and compare to what you have.the fact the bike was running fine for the first 100 miles driven at relatively low speeds with no harsh acceleration when this fault developed,ive been looking for obvious things like damaged parts or out of place parts and not really gave thought to worn parts so as theres nothing obviously out of place i`ll need to start checking tolerances in various parts especially rocker gear.