When to change Cam Chain

[akanana]

I recently changed the cam chain on my 2007 YZ450F after the chain slipped a tooth or two when kick starting the bike, the bike runs fine now, but my questions are:

1. After how many hours should I change the cam chain considering my riding is mostly in sand dunes which I assume hard on the engine. (I now have an hour meter!!)

2. Is there a test you can perform to check if the cam chain needs chaning.

3. When aligning the two dots on the cams with TDC, which dots should I pick? I learned the hard way that there is more than one dot per cam shaft!

Thanks a lot in advance. If it was not for Thumper talk I would have not ventured into changing the cam chain:banana: .

AK

[426 NOOB]

I recently changed the cam chain on my 2007 YZ450F after the chain slipped a tooth or two when kick starting the bike, the bike runs fine now, but my questions are:

1. After how many hours should I change the cam chain considering my riding is mostly in sand dunes which I assume hard on the engine. (I now have an hour meter!!)

2. Is there a test you can perform to check if the cam chain needs chaning.

3. When aligning the two dots on the cams with TDC, which dots should I pick? I learned the hard way that there is more than one dot per cam shaft!

Thanks a lot in advance. If it was not for Thumper talk I would have not ventured into changing the cam chain:banana: .

AK

most people will argue that it is so cheap that it should be done once a season. small price to pay. I believe that the manual has some kind of procedure to see if the tensioner or chain needs to be replaced, check there first. Not sure about the cams though, manual for this one too. If you dont have one they are posted in the common threads sticky.

[matt4x4]

My way is to do it with every piston change. Typically, I re-ring between 40-50 hours and change the piston between 80-100 to be safe.

So IMO 80-100 hours. This is based on my riding style which is NOT WFOATFT

(Wide Full Open All The **** Time)

[ace402]

At least once a year. Twice if you really want to be safe.

[grayracer513]

For cam timing info, download a manual here:

http://www.yamaha-motor-europe.com/community/service/manuals.jsp

The exhaust cam has two marks. position one at 9:00 o'clock and the other at 12:00. Align the 9:00 mark with the cam cover gasket surface as nearly as possible with the engine at TDC.

The intake usually has 3 marks (E, a dot, and I), but may have 2. If 3, put the dot at 12:00 and align the I with the head as above. If two, put one at 12:00 and the other at 3:00 and align the mark at 3:00 with the head.

Roll the crank and cams backward about 5-10 degrees, then turn the crank forward to TDC and double check.

[rdefonce]

I just replaced mine, and it was a straight forward job ACCEPT for getting the new chain on!

Gray, in your explanation you mentioned if the tensioner doesn't easily come out, to just drop it out'a the way, which I did. Are you able to install new chain with tensioner still in motor? I finally got it but it was a B&**@ch!

[grayracer513]

I just replaced mine, and it was a straight forward job ACCEPT for getting the new chain on!

Gray, in your explanation you mentioned if the tensioner doesn't easily come out, to just drop it out'a the way, which I did. Are you able to install new chain with tensioner still in motor? I finally got it but it was a B&**@ch!

I have no idea why you had so much trouble with this. With the rear tensioner shoe unbolted from near the crankshaft, and sitting down in the case, hold the chain sideways and lower it down between the front guide and the crank. Then pull the near edge of the chain outward far enough to get around the end of the crank and rotate the chain to get it over the crank (counterclockwise, vertically). Piece of cake.

[rdefonce]

I have no idea why you had so much trouble with this. With the rear tensioner shoe unbolted from near the crankshaft, and sitting down in the case, hold the chain sideways and lower it down between the front guide and the crank. Then pull the near edge of the chain outward far enough to get around the end of the crank and rotate the chain to get it over the crank (counterclockwise, vertically). Piece of cake.

Man! Guess I was doing it backwards; putting it on the crank first, then working it over the cam sprockets. Next time I will put it on cam sprockets first, then over the crank sprocket.

[grayracer513]

OK, I see where your problem was now. The rear tensioner shoe only needs to be off in order to get the chain onto or off of the crank sprocket. It has nothing to do with getting the chain onto the cam sprockets. The chain cannot be either taken off of or put onto the cam sprockets unless the cams are removed from the head, and the chain has to be on the crank first.. To reinstall, place the exhaust cam over the center of the head and place the cam chain over the exhaust cam sprocket. Roll the cam into place and get the timing lined up as well as possible. At this point, be sure you do not have any free chain hanging off the crank sprocket. Again placing the cam in the center of the head, count pins between the 12:00 o'clock marks on the two cams (13 if it's a 426 with a 426 exhaust cam or a 450, 14 if it's a 426 with 450 cam in it) and roll the intake cam down into place. Back up both cams and the crank about 10 degrees and then turn the crank forward to TDC. Double check the timing and correct as needed.

[426 NOOB]

(Wide Full Open All The *** Time)

just so you know WFO (biker term) stands for wide *** open. lol

[rdefonce]

OK, I see where your problem was now. The rear tensioner shoe only needs to be off in order to get the chain onto or off of the crank sprocket. It has nothing to do with getting the chain onto the cam sprockets. The chain cannot be either taken off of or put onto the cam sprockets unless the cams are removed from the head, and the chain has to be on the crank first.. To reinstall, place the exhaust cam over the center of the head and place the cam chain over the exhaust cam sprocket. Roll the cam into place and get the timing lined up as well as possible. At this point, be sure you do not have any free chain hanging off the crank sprocket. Again placing the cam in the center of the head, count pins between the 12:00 o'clock marks on the two cams (13 if it's a 426 with a 426 exhaust cam or a 450, 14 if it's a 426 with 450 cam in it) and roll the intake cam down into place. Back up both cams and the crank about 10 degrees and then turn the crank forward to TDC. Double check the timing and correct as needed.

Gray, got it. Thanks for the detailed info, I will print this out for future ref!