06 YZ450 Jumping Time

My 06 YZ450 conked out on me yesterday in the dunes. It turns out it jumped cam timing. I reset the timing thinking that maybe it was just a fluke since I was on it pretty hard. It started a couple of times and then did it again. The timing chain is less than a year old, but I know that doesn't always mean much. Is there a way to test the chain tensioner spring?



I would check your cam chain tensioner. Does it have any slack in it if you put the tensioner on? What do the teeth on your cam look like? Where the cam and cam chain replaced at the same time?

I know sometimes the automatic stock tensioners can get stuck or not work correctly...I would clean that best you can and see if its the issue....You don't want it jumping timing too bad or you can have a real problem on yo0ur hands.

The teeth look fine, I need to pull the tensioner again and give it a good cleaning. But, what I am wondering is if there is some sort of spec the spring should be at.....?


New tensioner

Anything else I should be looking for besides tensioner and chain?

If it hasnt been apart then not to worry, but cam cap torque, overdid them before on my rx1 motor(just another 5 valve yami motor) and it caused it to jump the chain and smoke a set of valves on the pistons.

Okay, fixed :thumbsup: I went ahead and replaced the chain and tensioner. But it looks like it was the chain that failed, it has some "tight" spots. I think it was going before my trip to the sand, the bike seemed a little doggy (but not by much) right before we left. Of course the emergency carb cleaning when it first quit probably didn't hurt.

Now for my next question, that timing chain was less than a year old. I don't race, but I am a big guy and I ride some pretty tight/steep stuff in the summer and I was on it pretty hard in the dunes on some of the big hills. I generally try to use OEM parts, but I am wondering if I shouldn't use an aftermarket chain the next time?

The OEM chain is the same exact part as at least one of the $60 aftermarket chains available. I'd be more concerned about your oil. The usual way the chain fails is the links start binding up, which is what I believe leads to at least half the cases of skipping time. Most of the time when I've seen that there have been questions about how well maintained the bike was.

Good to know. I am pretty fussy about changing the oil. I change it almost every ride in the summer (when the weather is hot) and every 2-3 rides when the weather is cooler depending on how hard the bike was working. I am using a washable oil filter, do those typically have issues with filtering well enough?

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