Reply To: Valve clearance, camshaft, camshaft tensioner – a problem or a serious fault?
Hi, I haven’t been here for a while because I was struggling with the availability of parts, and whenever I took something apart, new unwanted parts came out that were simply worn out. I removed the magnet wheel and replaced the timing chains. I compared the timing chains to new ones and it seemed as if they had stretched by as much as 2 pins. Is it possible for these chains to stretch that much? I don’t know if I measured them correctly, placing one against the other, against a flat metal element as a starting point (one full chain link, two pins) and stretching them lengthwise and comparing them visually (I didn’t measure them with a tape measure).
I replaced practically all the seals I encountered along the way, except for one that is in the cylinder cover and seals the spark plug.
Not to mention the repairs of broken threads (two in the cylinder in the camshaft bearing mountings and two from the cylinder cover mounting…).
Everything I did, I did according to best practice and the service manual. Everything I removed from the motorcycle that was described in the service manual, I measured, checked for compatibility, and if it was incompatible, I replaced it, and if it was compatible, I put it back in. I recorded every step of my work with a GoPro, so I tried to put everything back together in the same order and sequence as I took it apart (of course, confirming everything with the service manual to make sure it was correct). I tightened each screw with a torque wrench and applied threadlocker where indicated in the service manual.
The valve clearances are currently as follows:
Front
0.15 (IN) 0.13
0.24 (EX) 0.26
Rear
0.13 (IN) 0.14
0.26 (EX) 0.24
I performed the cylinder compression test again, which now looks like this:
Front – 10.2 kg/cm2
Rear – 10.6 kg/cm2
The compression test was performed with a drop of oil poured onto the piston.
I read your answers regarding the tensioners, and I installed specially ordered 0.5 mm thick gaskets under each one (the same as the ones that were installed previously). Both the front and rear cylinders had only two holes for screws, none of them had a third hole. Unless we are talking about a milled groove inside the tensioner hole?
Generally speaking, before the entire replacement procedure, after opening the rear cylinder, you could see the chain jumping on the sprocket – as if the tensioner was not tightened. But it was not possible to tighten this chain. After replacement, this effect is not present when turning the magneto by hand.
I am currently in the process of putting everything back together, I still have to install the airbox on the carburettors, install the tank, connect everything and fill it up to start it. If the bike heats up and continues to make noise, the rear tensioner will be the first to go.
My question is, what if the tensioner is replaced and it still makes noise? Where should I look for the cause? Could it be that one of the valve springs has reached the end of its life?