top cam chain roller wear

[gray]

Yearly oil change for the season ahead done today. Some thin tiny flakes of metal on the magnetic drain plug ( ie steel) and some greyish gooey deposit too (alloy?) The engine has been a bit clicky from the rear of the cylinder head over the last year or so, not improved by doing shims, balancing carbs etc.
decided to get it on the bench and start having a look- looks like there is some wear on the top idler. No up and down or front to rear play. you can see that the central bearing bush is loose in the bearing - it moves along the central shaft independently of the outer part of the cam sprocket. And you can wobble the sprocket so it can point towards the Left indicator then the Right indicator.
How much play is acceptable?
And is this the likely culprit or should I delve deeper?

[zed1015]

Slight side float of the whole idler sprocket is normal but wobble isn't.
if the outer sprocket ring and rubber center have unbonded it must be replaced.

[gray]

yeah that's what I thought / was afraid of . I'll try replacing it then see if it helps.

[gray]

took the top roller out , ground off 1 end of the central pin and drifted it out. 1 of the side strengthening plated was loose, the spot welds had failed. The roller centre almost fell out of the sprocket centre.
However it doesn't really explain the greyish goo in the sump Looking up into the gearbox no obvious clues or signs of wear or grinding, nor inside the clutch cavity or the stator cavity when I took the covers off to look.

[zed1015]

Greyish goo may be Mayonaise.
Oil and water emulsion due to condensation build up .
Gets worse in cold weather or when the engine is run but not allowed to get fully hot enough to evaporate the excess moisture.
Either that or just accumulated sludge from contaminants and piston blow by over many years.

You will most likely need to replace all the idlers and wheels as they will all be on their last legs and close to failing in the near future.

[Gray17]

As you will see from some of my posts on the Forum i am doing a full restoration of my Z900, part of which was full engine strip to vapour blast cases. Now back from blasters and on with rebuild.
Like you i found thick mud like substance in sump several mm thick, mine was charcoally black rather then grey, im guessing like yours probably years of oil/water and in my case rubber mix as a couple of my rollers centres had collapsed and part of it in sump. Guessing it hasnt had regular oil chamges in its 48 years, probably sat in garage most of time. Luckily my tensioner and top roller are all perfect but will be checking all the spot welds thats for sure.
Hope you get yours sorted, i suppose the question is do you replace the danaged one and leave it at that, or strip full engine to check all just in case theres more issues, that a dilemma i didnt have as everything had to be removed for vapour blasting.
Keep us all posted.

[gray]

My bike gets an oil change every year at this time , and although high mileage ( 105k) only did 1000 miles last year.
the magnetic sump plug showed some tiny steel shards as well as the greyish goo that swirls and shimmers slightly when you shine a torch on it ( making me think it was metallic contamination )

[gray]

It had a full engine strip at 100k so the sump was cleared at that time. I replaced the 2 lower adjuster rollers and the plain cam chain roller at that time

[gray]

I've ordered a top cam idler and will put it together and see how it goes I think