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Valve Timing Question

Old 05-30-2006, 08:49 AM
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Valve Timing Question

What performance issues would I have if my valve timing was off one tooth on only one cylinder?
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Old 05-30-2006, 09:49 AM
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It depends if its advanced or retarded. It should run but not smoothy.

Do you know how to check if your cam chains are timed right? Pull the big allen bolt on the left side engine case and your vlave covers. The timing marks are on the cam sprockets and inside the allen hole. Good luck!
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Old 05-30-2006, 10:46 AM
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Yes, I know how to, I have the service manual, but the marks on the cams do not line up perfectly on either cylinder if I put the crank to RT mark and FT marks, so I am concerned that maybe They would be off slightly. The bike starts great, and idles perfectly, revs right up to around 6000 rpm before I start to notice anything slightly wrong. Almost feels like it is starving fuel, but when I tested the petcock, the gas dumped out, so I know that is not the problem. I can get it to rev a little higher, but not very smoothly. I am not sure if it is valve timing, or electronic, or fuel. I just wanted to get some input as to what effect incorrect valve timing would have. I would rather not start playing with that, if I don't have to.
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Old 05-30-2006, 11:52 AM
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The marks on my bike line up perfect. Did you put tension on the valvetrain (put in 5th gear and turn rear wheel to get the slack out of the cam chain)?
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Old 05-30-2006, 06:43 PM
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I've got 50,000km on it, so I am pretty sure my chains are slightly stretched.. I talk to one bike mechanic about it, and he said that he rarely sees them line up perfectly. I know that I have not changed the timing on the rear cylinder because I learned from doing the front how not to let the chains jump when changing the CCTs. So I lined up the front cylinder at pretty much the exact same plave as the rear. both cams are slightly retarded. About a half tooth or so. Do you think I should try and move both of my cams so that they are both advanced a half tooth?
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Old 05-30-2006, 09:22 PM
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Hmmm...

If you think the chains are stretched and thats why they won't line up I would replace the chains. The bike I timed had 28k miles so it had a few miles. The manual wasn't very straight forward so I had to mess around with it for while before I got the perfect lineup. Are the cam marks atleast lining up with the head? If so I would say stretched chain or keep messing around with it. If the cams won't time with the head I would say you have a badly stretched cam chain.

I can dig out my manual if you want.
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Old 05-31-2006, 04:42 AM
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I have done a complete rebuild on my engine so have new everything, and my timing marks line up perfectly. Fixing this would be a good start to fixing your problem.
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Old 05-31-2006, 01:59 PM
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Okay... So if I have both cams timed one tooth retarded, on both cylinders, would the bike still idle smooth, and perform not too badly at low RPMs? But then start to act like a poo face at higher RPMs??
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Old 05-31-2006, 02:25 PM
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Its really hard to say. You need to take care of your cam timing problem first before you try anything else. Otherwise you'll never know where the problem oriniated.
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Old 05-31-2006, 07:15 PM
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Are both front and rear marks off by the same amount?
It would be relatively easy to reset the rear cyl one tooth and spin the crank a couple of times to see how close the timing marks look afterwards.
I'm not sure how many teeth on the cam gear ( about 44 ?) which would be about 8° per tooth .... or about 16° on the crank. Sure seems like more than enough to mess with performance in a big way.
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Old 06-01-2006, 02:49 PM
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See, I am not worried with moving the cams around and playing with it in that way, but if I can spin the crank, with no issues, or hitting, is it possible to smash a valve? I am pretty sure that both sets of cams are off the exact same ammount, so that is why I thought it was not set on the wrong teeth. I am also curious to know how hard it would be to change the cam chains? Do I have to pull the crank? Also, the marks on my crank, do I line it up with the letters, or the little line? I have been using the little line beside the FT, and RT marks. IS this correct?
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Old 06-01-2006, 03:26 PM
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Originally Posted by dustinwild
See, I am not worried with moving the cams around and playing with it in that way, but if I can spin the crank, with no issues, or hitting, is it possible to smash a valve? I am pretty sure that both sets of cams are off the exact same ammount, so that is why I thought it was not set on the wrong teeth. I am also curious to know how hard it would be to change the cam chains? Do I have to pull the crank? Also, the marks on my crank, do I line it up with the letters, or the little line? I have been using the little line beside the FT, and RT marks. IS this correct?
I've often thought I'd like to retime the valves ... trial and error just to see what performance changes I could come up with. The cam sprockets would need to have the mounting bolt holes enlarged a bit to allow for retuning but as you probably know these change are usually done on the order of just a few degrees, in either direction. Obviously, reseting the cam sprocket by one tooth is a big change. I'm not sure how critical the valve clearance is here for a change like that but a slow turn of the crank will quickly tell you if there is an immediate problem. I doubt a 1 tooth change would slap the valves though.

yes, the line next to FT and RT is the correct set point.

As far as changing the cam chains goes. I've not done it but I'd think it'd be just like installing a new drive chain.
ie: grind a link pin head, press out the pin and then wire the new chain to the end of the old, pull it through, press a new link into the new chain....
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Old 06-01-2006, 03:46 PM
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the engine has quite a bit of valve-piston clearance, so one tooth probably woudn't be an issue.

replacement of the timing chains requires everything up to, but not including splitting the cases. i.e. removing clutch, primary drive gears, oil pump and water pump drives, flywheel, etc.

I woudl try to get the timing marks lined up first. If you are rotating the engine forward and the tensioners are in place they should line up.
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Old 06-16-2006, 05:03 PM
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Well, I finally took my bike in to a mechanic and had him have a look at it.. He was shocked.. He heard me ride up on it, and he said, there is something wrong with it... So, I left it with him, and he tore into it to find out that the front Cylinder was out of timing one full rotation of the cams. But, the bike still started perfectly, idled great, had good low end torque... Now, I can't figure that one out. How does it run virtually perfect if the cams are out a full 360 degrees? Wow.. I was going to try and move the cams a tooth here, and a tooth there, but I didn't want to smash a valve again, so I took it in. I would have never guessed a full rotation out... Damn hard to read manual. I think I should go and buy one so that it is easier to read. Who would have guessed!!!
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Old 06-16-2006, 05:11 PM
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So I gotta ask...how does it run now?

Reason I ask is that one full rotation of the cams is the same thing as what you started with. One full rotation of the CRANK is different. That must be what he meant.
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Old 06-16-2006, 05:21 PM
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Obvious. If its wrong, it won't be subtle.
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Old 06-16-2006, 06:48 PM
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Sounds fishy to me .. as Greg pointed out one rotation on the cam puts you back where you started.

One rotation off on the crank for the front cyl and I don't see the engine running at all, ie: intake down stroke pulls from the pipe.... the exhaust stroke goes back through the carb into the air box .....
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Old 06-16-2006, 07:36 PM
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Well, I'm not sure... He said that the cams were out one full revolution. Basically so that it would spark one stroke off... Hmmm... I don't know.. It really doesn't make too much sense to me. I will have to get the bike back and figure it all out. I trust the mechanic though, he is a good friend of mine so I know that he wouldn't screw me over. It's not like I took it into a bike shop and trusted any of them crooks.. Heck, I used to work at a bike shop, I know what they do!! This guy is a machinist for his day job, and works on bike on the side. Used to be a tuner for a racing team here in the city. He makes custom machined cams, and machines heads, ports, and all that... He knows a ton about this kind of stuff. He tried to explain it to me over the phone, and I just couldn't quite follow it. I can't wait to get her back though!!! I miss her so! I have been bombing around on my brothers ZX9R for the last little while to tie me over... It's just not the same...
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