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cams keep jumping out of time

H

hyprst

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Dec 21, 2009
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n.w. in
09 fx with 2700 miles rode perfect into the garage, made a clutch weight adjustment, turned the clutch by hand and heard clicking from under the valve cover, needless to say it wouldnt start so I pulled the valve cover and noticed the chain had slack and was jumping over the sprockets. Lifted engine to get at the tensioner to reset it, retimed the cams , released the tensioner turned over by hand again and the chain still jumps the sprockets. Doesnt appear to have a broken chain slide , guess I ll have to completely remove the engine and look in the side cover. Open to solutions if anyone has ran across this same problem.
 

If you rotated the engine backwards when working on the clutch you may have put slack in the timing chain. Because it wouldn't start I'd be concerned that it may have jumped far enough to cause piston/valve damage. I'd inspect the engine for wear/damage and if everything looks OK, replace the tensioner. Follow the procedure in the RS section.
 
I was concerned about bent valves so I removed the cams and did a leak down test everything is sealing good. Grizz Have you seen tensioners fail?
 
I've only seen failures in the 05-07 three cylinders engines. This is the first FX engine that I've heard about having an issue. The chain and gears on theses engines are not very heavy. Any slack at all in the chain will cause it to jump time. The timing sequence is to exhaust then intake. When this happens the exhaust lobe is not fully off of the valve when the intake lobe starts to open a valve. The spring in the exhaust valve pushes on the cam lobe which rotates it toward the intake cam leaving slack between the two cam gears. Normally it's the intake gear that jumps time. I think the fix for the 05-07 engines was to put a stronger spring in the new tensioner so that as the chain and gears wear it can take up the slack better.

Never rotate these engines in the reverse directions.
 
I had a Apex motor jump time. I think the tensioner went bad. Mine happened when riding tho... Motor was junk.

Does it turn over when your trying to start it? I would assume so. I would for sure get a new tensioner.
 
I did make the mistake of rotating the engine in reverse and it definitely jumped 2 teeth from cam to cam. I ve reset the cam timing 3 times and just turning the clutch (in the right direction by hand) the cams do exactly as grizz says they load and unload cause slack between cams and it jumps one tooth. Ive tried prying the tensioner slide so the tensioner can extend to the next lock groove to keep enough tension until the start up can fully pressurize the tensioner. Only thing I can figure is the wire spring clip in the tensioner got damaged being forced back by rotating the engine in reverse.
 
I've used tie straps on the cams to hold the chain to the gears then rotated the engine as far as possible to allow the tensioner to take up slack. You need to repositions the straps on the gears several times and make at least one revolution of the crank so that the tensioner takes up all the slack.
 
Tried the tie straps still cant get it to stay in time , ordered a new tensioner assmebly. Thanks grizz for the help , will keep you posted.
 
Got to the bottom of things tonite the chain guide on the tensioner side is cracked just above the mounting pivot bolt allowing the chain to slack and jump time.
 
If that's the only damage you got lucky. I'm surprised it didn't bend valves. Get it back together and get back out there. The season isn't over yet!
 
Hey, while the engine is out you might as well bore and stroke it. Maybe a turbo and nitrous also?
 
Mr. Oz will do all of the above only if I can use your hotel bathtub to clean and prep the engine for reassembly after a burn down.
 
Got the new parts today and yamaha has redesigned the tensioner side chain guide, the arc from the pivot hole has been moved, allowing the guide to ride closer to the chain and keeping the chain tight on the crank sprocket even when the tensioner is compressed. I took pics of it but cant figure out how to upload them.
 
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