Replacing the fixed cam chain tensioner(s)

Can anyone confirm that you can change the R/H one without removing the gearbox? Its the one that has the big nut on the barrel for the tensioner.

Yes, the right hand one pivots on a mounting bolt under the plug at the bottom of the right barrel. I'll see if I can get a pic for you. I think you can anyway. I have only done them during full engine rebuilds but from memory it's all accessible. The plug for the left hand one is. Behind the flywheel. Everything has to come off.

Thats promising to hear.

The roller cams still look good after 72,000 mile - pleased about that!

Pete, I found some pictures of an engine on ebay which show the nuts.

I have an addtional question:-

The tensioner plunger -
1, to double check the thin end goes onto the tensioner blade?
2, will it refill with oil if it has been cleaned

thanks

The tensioner plungers are different on the two cylinders. I'm on holiday in NZ at the moment and can't check which is which for sure but the priming end, the end with the ball valve, goes to the bottom of the reservoir so it can prime up when the motor starts.

If the issue is that the chains are rattling check and replace the sump spacer gasket first. This having blown out is by far the most likely cause of rattling chains rather than an inability for the ball valve to seat due to contamination.

Thank for the reply, I have discovered that the "easy" side pivot bolt is masked by the tensioner from the other side so cannot be removed without the other

So at this point it looks like an engine out job.

The tensioner blade is physically broken which is why I am trying to replace it (don't know why it broke)

I can't envision what you actually mean by this? How did the blade get snapped? The only one I ever snapped was entirely my fault. It happened when I was collapsing the tensioner plunger and I hadn't got the screwdriver down far enough between the blade and the chain. I seem to remember that was an engine out job too?? Only other time I've replaced them was as part of a full rebuild......

I left work one night and the bike felt a bit rough, went to get fuel and when I restarted one side sounded like a bag of nails and the bike didn't want to rev.

Got recovered and back home did some checks
cylinder pressure on bad side went up to 212psi good side 160psi
valve train was operating
took breather cap off head and the splash plate thingy to check cam timing and found that this had shifted bit.

The last time I did the cam timing (roller conv') was at 17K and now the bike has done 103K mile.

Oil get changed at 6k intervals

Took the head off to see if valves were ok and the piston was marked or not. All OK

The loose tensioner guide is OK, the fixed one - I'm not sure if it was fractured or if I was clumsy to be honest.

So having removed the cap the gain access to the tensioner pivot pin, it appears to have something in front of it stopping me, that looks like another tensioner blade.  I think that I shall take another look and see if I can do anything or will have to remove the frame from the engine.

OK, the 200+ cranking pressure is a dead set give away that the cam timing is a tooth out. Now unless the flinger plate was installed in such a way that one of the 'Bigger' holes in it was above the timing pin and the pin has wriggled its way out of the sprocket this simply can't happen by the timing 'Moving'. The primary timing is by gear, if that was wrong both cylinders would be exhibiting weird cranking pressures, (Not to mention the phonic wheel would be mis-timed so injection and ignition would be all wrong.) not just one. I'm not even sure if by 2011 there were still the 'Large' holes in the flinger plates? It was about that time the design was changed and the 'Large' holes were deleted. Why they were ever there in the first place is beyond me? They serve no useful purpose.

I suppose the other possibility is that the sprocket could be timed to the wrong hole? There are two holes in the sprockets, they are marked 'L' and 'R' for obvious reasons but if the wrong one is used that too would throw out the timing causing the high ranking pressure but I'd also be surprised if it didn't cause a collision event as well.

As for the whole business with the tensioner blade/s I'm scratching my head??? If the mobile blade is fine then it follows that whatever you can see through the mounting pin plug for it has to be something else. The problem is what? I'm surprised in fact that anything could fit between the plug and the head of the locator pin for the mobile tensioner blade? From memory everything is pretty tight in there. Then there is the question of what this random bit might be? The second blade isn't really a tensioner, it's simply a guide put in to protect the alloy of the camchain tunnel being walloped by the chain in the few revolutions before the tensioner plunger pumps up and tensions the chain. It sits in a slot in the crankcase at the bottom and has *ears* that sit in a slot in the barrel at the top of the cylinder to locate it. Once it's installed it can't move as it's held in place by the head and if it was somehow not located at the bottom it would be poking out into the chain run to such an extent that I'd think it would firstly be damn near impossible to get the sprocket back on the cam but if you did manage it the pressure on it would be phenomenal and it would of broken up or caused some other catastrophe as soon as the motor was started! It certainly wouldn't of lasted some 10,000 miles!

Anyway, I think we can take it as a given it was mis-timed on assembly. This always results in a great unwillingness to rev much above 6.5K but I suppose it's possible to not notice that if you don't take it up there very often, (To be honest, as time goes on I spend less and less time there!). That needs to be corrected but with the issue with the tensioner or whatever it is that is seemingly blocking the access to the pivot pin of the mobile tensioner blade? That should be accessible on the left hand cylinder at least simply by pulling the head and barrel that side. Indeed if it is a busted guide blade you might even be able to just lift the cylinder up without even fully removing it which would hopefully enable you to pluck out the remains of the offending item and, if it is indeed part of a busted guide blade, replace the blade after re-seating the barrel. Yes of course in such a situation one should replace the base gasket but as we know there is no requirement to do this when an engine is rollerised. The gasket is decompressed and then recompressed again and leaks rarely occur. I can't offhand remember one in the entire large number of engines we've done. I don't know if the gaskets are coated steel or some sort of alloy or maybe a polymer but they are certainly robust and if you can extract and replace any bit of dead whatever is in the camchain tunnel without liberating the rings from the bore so much the better. I'd risk it anyway.

While he head is off I'd wet test it but the high cranking pressure would seem to indicate it's OK. Might be worth spending a few bucks on some valve guide oil seals and checking for guide wear while it's off though.

Anyway, I'd follow that path prior to pulling the engine out of the frame although on a Sport you might have to just lower the engine in the frame to lift the barrel as from memory the back of the cylinder clonks the frame if it's still bolted in place.

Thank you for the detailed thoughts, gives me something to work on.

I cant agree on the mis-timing as I normally do a compression test around every 12,000 miles or so just as a reference to see if performance is dropping off.  Both sides have been quite close ever since I started taking readings, so that covers about 80,000 miles.  So for the drastic change in cylinder pressure indicates something did happen recently as the last pressure check was about 3,000 miles ago.

I do have some valve seals so can drop the valves and check

Thanks for the tip about lowering the front of engine to remove the barrel.

You aren't running a 'Fat Duc' or one of the other air temperature or lambda sensor foolers are you? That's the only other reason I can think that the camchain might of got so loose as to skip a tooth.

No nothing like that

I'll keep you posted on what I find

Just a brief update

The Left hand fixed tensioner covers the right hand moving tensioner

Both right hand tensioners were damaged and the cam chain too.

Have replaced all 4 tensioner blades and 2 new cam chains

Can you expand a bit on the left hand fixed tensioner covering the right hand moving tensioner? I don't understand what you mean.

Hi Pete

we were discussing whether it was possible to swap the right hand pivoting tensioner without taking the engine out as the large cap is visible (whereas the left one is behind the clutch flywheel. I had mentioned I couldn't remove the pivoting blade as something was blocking access to the bolt. This turned out to be the left hand fixed tensioner covering the hole.

Hope that makes sense?

Does this pic help ?

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Ah, gotcha. Interesting. I must never of tried it without the head off.