Yamaha TRX850 Enthusiasts Forum

Hi guys bike has done 36,000 miles and am about to subject it to increased milage due to change of job

Thinking about changing cam chain

How easy is it to change the cam chain without breaking it?

has anyone got experience of riveting a hyvo cam chain, is it a good idea? - don't want to risk wrecking engine, but also don't want to go to a lot of unecessary work.

Im a bit stale on what you need to do to change the cam chain.... here goes: valve gear cover off, release cam chain tensioner, remove lower panel enclosing the oil pumps (Im a bit foggy as to what greets you in there apart from the pumps) and here you have access to the chain as it passes around the crankshaft sprocket,.... back to the top and you remove the front chain slipper by pulling it upwards (do you need the engine out of the frame for this, I had it out anyway), remove one of the cam sprockets, the inlet is probably easier .....and then the chain is loose and able to be removed by passing it through past the crankshaft sprocket and out where the lower outer panel was. I remember one manual (on the net for free I think) tells you what can be done if the engine remains in the frame..........when reassembling just do the opposite to removing the old chain but get the marks on the alternator/flywheel to coincide with the marks on the two cam sprockets as they relate to the cam cover mating face on the head. You may notice a disparity between the inlet and outlet cam sprocket markings, this is often the case and entirely normal for these bikes. If you want to check for cam chain wear compare the alternator flywheel markings with the two cam sprocket markings. The inlet is the most accurate (I think the exhaust marking often trails behind the inlet marking by about a third of a tooth. This is the funny thing about TRX,s though some TRX,s have markings that all align). If the flywheel markings are ahead of the inlet cam sprocket markings then you have cam chain stretch. If it were my bike I would not be concerned if the flywheel markings were only slightly ahead of the inlet cam sprockets. You will not notice any performance loss, as it will be minimal, and the chain will most likely be a goody. It's a matter of how ahead the flywheel marks are.
When reassembling the engine do remember to loctite and thoroughly tighten the cam sprocket bolts....it's not hard to forget to do this , in your moment of victory ..... and the camshafts have holes or hex's (holes I think) so that you can rotate them and also hold them while tightening up the sprocket bolts.
To join the new chain (if it's not continous) you need a "soft" link which you will peen over the two pins with the link placed on a hard steel surface, before you put the chain in the bike......
I reckon it's first worth evaluating whether the chain needs replacing before you commit to surgery.... Cheers

The tensioner is set at - what? All the way in? If so replace chain, otherwise... why?

As I said earlier, I am now doing a 60 mile round trip commute a lot at high speed, so reliability becomes more of an issue

I did try to get a feel for how much wear is acceptable on the cam chain i.e. how many clicks on the tensioner, but got no helpful answers. A mechanic who does a fair amount of work on TRX's said that camchains wearing and jumping a few teeth on the sprocket was not unknown and if this happened a lot of damage was done. As a result am seriously considering changing the camchain as aprecaution