Difficulty of replacing a cam chain

Basically, I want to know if I'm in over my head. I haven't ordered the bits and peices yet, since I want to pull it apart and see what I need. I'm new to four stroke mechanics (I know the basics) so give some leeway on misnamed parts. I pulled off the (valve cover?) to expose the valve train. I see the rocker arms (yea?) valves, valve springs, cam, cam chain. The chain I think needs replacing, I can wiggle it around and pull it upwards slightly from the (cam gear?). How much further do I have to delve into this to replace the chain, and do I need to replace the tensioner? One other question, if I pull this next layer off, are the valve springs going to like, pop out, thus requiring me to buy a valve spring compressor? :thumbsup: I know, a lot of questions, but help me through!

haha, no, the valve springs will not "pop off" the head all comes off as one piece (including the whole valve train). the next section under the head would be cylinder. nothing special their. as for serviceable limit on your cam chain. im not sure, prolly refer to a service manual if you can. also, i have yet to see a 4-stroke where you can remove the cam chain WITHOUT removing the crankshaft (or at least sliding it out a little). probably wait for a more knowledgeable person to answer.

the cam chain stretches over time, after a while your timing is a few degree's out, loosing you power, but mroe worrying (particulary if you own a yamaha) is that if you leave it to long, the timing gears wills start to wear (just like a stretched chain will wear your front and rear sprockets), which will then also need replacing, back to it being very bad if you own a yamaha, the timing gear on the crank in a yamaha engine is not detachable, it is machined along with the crank, so if yuo own a yamaha and you let it stretch to that point, you'll need a whole enw crank.

best time to do the chain is when you do the top end, around 50-100 hours as a rough guide (depends if you ride hard, if you on the rev limiter a lot it wear's the cam chain so much faster)

I have yet to purchase the repair manual, as I just got the bike. The cam chain was adjusted to its fullest extent just a few weeks ago when the guy got the valves adjusted, and I THINK he said that they took a link out of it. I was just somewhat worried, as it makes a lot of noise (03 CRF450) it IS a unicam, and I've heard they're loud. I just dont want it to throw the chain or whatever, and blow a valve through my new bike :thumbsup:

I have yet to purchase the repair manual, as I just got the bike. The cam chain was adjusted to its fullest extent just a few weeks ago when the guy got the valves adjusted, and I THINK he said that they took a link out of it. I was just somewhat worried, as it makes a lot of noise (03 CRF450) it IS a unicam, and I've heard they're loud. I just dont want it to throw the chain or whatever, and blow a valve through my new bike :thumbsup:

You need a manual ASAP. you can't take a link out of a cam chain as you would a drive chain. The valve timing depends on the chain being the correct length and tightness. Most cam chains I have seen are not really adjustable, the auto-tensioner provides the correct tension assuming the chain is not stretched.

+1 on the manual. On my bikes, there is a guide to keep the cam chain on the crankshaft so you don't have to mess with that everytime you do something with the top end. This means you have to remove the flywheel to get to the guide so you can remove the cam chain.

Look on ebay for a flywheel puller for your bike or go to the dealer. The manual will help you, step by step, through the process and remove all mystery.

Have fun!

Dave

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