Cam timing

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redneksoldier

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So, first, a little back story...
Beginning of summer I rebuilt the motor on my '94. I had pulled the motor for second gear fix and found the oil pump o-ring issue and some main bearing damage. I also discovered that somebody had been in the motor before. Both cam chain tensioner guides were broken, which I picked up a used set from Sean for an exceptional price. New bearings, rings, seals trans, and HD oiler installed and it was running like a top again.

Fast forward to 2 weeks ago...

On my way home from work, after getting off the freeway, the bike was running rough and lacked power badly! Seemed like it was running on 2 cylinders. I limped it on home a few miles and parked it. Started it up the next morning and it seemed to idle fine, but was really flat and popped back through the carbs when I gave it some throttle. My mind went immediately to ignition (ignitech and cops) or carb issues. Troubleshoot the ignition, no issues. Shotgunned the carbs, no improvement. Checked compression, 185-195psi on all 4. I happened to be standing behind the bike with it running on the lift. The exhaust note sounded funny. I put my hand over the pipe and it was pulsing pressure and suction. Hmmm, cam timing issue? Got the valve covers off and sure enough, front bank (#2 & #4) was out of time by 1 tooth.

I got the timing set back to the correct position today. Kind of hard to look down inside the engine to see the tensioner guides with the engine still in the frame. I have one of those cheap endoscope cameras that plugs into my cell phone. I'll poke it around in there and see what I can see before I button it up.

Has anyone else ever seen or heard of issues with cams jumping time?
 
Last edited:
So, first, a little back story...
Beginning of summer I rebuilt the motor on my '94. I had pulled the motor for second gear fix and found the oil pump o-ring issue and some main bearing damage. I also discovered that somebody had been in the motor before. Both cam chain tensioner guides were broken, which I picked up a used set from Sean for an exceptional price. New bearings, rings, seals trans, and HD oiler installed and it was running like a top again.

Fast forward to 2 weeks ago...

On my way home from work, after getting off the freeway, the bike was running rough and lacked power badly! Seemed like it was running on 2 cylinders. I limped it on home a few miles and parked it. Started it up the next morning and it seemed to idle fine, but was really flat and popped back through the carbs when I gave it some throttle. My mind went immediately to ignition (ignitech and cops) or carb issues. Troubleshoot the ignition, no issues. Shotgunned the carbs, no improvement. Checked compression, 185-195psi on all 4. I happened to be standing behind the bike with it running on the lift. The exhaust note sounded funny. I put my hand over the pipe and it was pulsing pressure and suction. Hmmm, cam timing issue? Got the valve covers off and sure enough, front bank (#2 & #4) was out of time by 1 tooth.

I got the timing set back to the correct position today. Kind of hard to look down inside the engine to see the tensioner guides with the engine still in the frame. I have one of those cheap endoscope cameras that plugs into my cell phone. I'll poke it around in there and see what I can see before I button it up.

Has anyone else ever seen or heard of issues with cams jumping time?

Which were broken? The ones on the tentioners side or?
I ask because I'm going to be inspecting my loud chain noises soon. Starting at the tentioners themselves.
 
The tensioner side was broken on both heads. The little cleat that seats into the block was broken off. I can't remember if it was the top or bottom that was broken. You can't replace those without pulling the heads. I'm going to check mine out in a few minutes. Going to try using my little inspection camera to get a look at it.
 
Well, got a good look at everything. Both tensioners and guides look good. The front chain was definitely loose when I took it apart, but it is tight now. The tensioner was working correctly.

There was only one thing I could figure might have been the cause:
The tensioner makes a permanent divot where it presses on the rubber coating of the guide. Maybe it wasn't seated properly. I don't know.

I'm going to put it back together and try again. I got lucky and it only jumped one tooth and didn't have any valve to piston contact.
 
Never heard of that? Just incorrect assembly is all i've heard before. I have heard only of a couple of broken tensioners in the past.
 
Never heard of that? Just incorrect assembly is all i've heard before. I have heard only of a couple of broken tensioners in the past.

Yeah, I'm pretty sure they were not seated correctly in the bottom of the block by whoever worked on the motor before I got the bike. That's the only way I can figure they got broke the first time. Just to clarify, I checked them with the mini cam and all is still good. Don't know how it jumped time, or why it waited 4000 miles to do it.
 

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