Post by jdbrees on Jun 15, 2008 11:09:50 GMT -5
I'm generally pretty good with most things mechanical, but I've been hesitant to relate this tale as I'm quite embarrassed about what I've done. I'm hoping someone here can help me sort things out after theyr'e done shaking their heads and laughing.
I bought Rodentrancher's '78 SR500 and have been very happy with it.
After getting a manual, I set out to do a tune up.
I started with the cam chain tensioner adjustment..............
Mistake #1: I completely misunderstood the mechanical arrangement of the lock-nut and adjuster mechanism. I thought the adjuster screw was the lock-nut and that the rod itself was the adjuster (it's got a a screw driver slot, right?). After rounding off the corners of the real adjuster screw's head, I thought I'd better try loosening the really big nut - at which point the real adjuster screw turned quite easily - duh!
Rounding the adjuster screws head distorted the round hole through which the rod must travel which resulted in the rod not being able to move freely at that end of its travel. To correct this, I ground a slight taper on the end of the rod to eliminate the interference. So far so good.
Had to take a break to take care of another task and had more than a few beers before getting back to the tune up
Mistake #2: Put the pieces of the adjuster mechanism back together in the wrong order and re-installed them. I feel so stupid, but I put the little rubber coated washer thing onto the rod first, then the spring, then the aduster screw. Put the whole mess back into the engine and started tightening. At some point past too far, I realized something wasn't right and started it back out. The spring had compressed until the coils were bound, and then simply began to distort as I had relentlessly kept wrenching on it. The rod and the smashed spring were all bound up in the cylinder head hole. With help from above, I managed to extract the mess from the hole using a thin screw driver and needle nosed pliers. The spring was rather distorted, but I managed to massage it back to a reasonable approximation of it's original shape. I reassembled everything in the proper order, set the adjustment per the book and had four days of uneventful commuting to work.
When I tried starting the bike after work on Thursday, the kick start lever would not move.....I thought to myself "how could the engine be frozen - it was running great when shut it off this morning". I double checked that the transmission was indeed in neutral and pushed a bit harder on the kick start lever. The lever moved a few inches and then would not spring back up. I pushed harder still and got a few more inches of movement but still no return. I shifted the transmission to top gear, pulled the clutch and pushed the bike and let go of the clutch to see if the engine's internals would move. They did. The kick start lever still had no return activity.
I put the transmission back into neutral and pushed the kickstart lever through it's full downward stroke by hand and then it came back up by itself (return spring now functional).
The bike then started and made the trip home. The shifting felt "notchy" though. I haven't ridden the bike since - I fear something internal broke when I tightened the incorrectly assembled cam chain tensioner and that pieces of it are now roaming freely through the bowels of the motor.
I'm in the process now draining the oil so as to check the filter and sump screen for debris. Will post later on the findings.
I am hoping one or more of the forums more knowledgeable can speculate on exactly what chain of unfortunate mechanical events occurred when I tightend the incorrectly assembled cam chain tensioner.
The effect on the rod assembly would be to have legthened it by the compressed height of the spring, thereby pushing on the adjuster lever with much more force than it was designed for.
Jerry
I bought Rodentrancher's '78 SR500 and have been very happy with it.
After getting a manual, I set out to do a tune up.
I started with the cam chain tensioner adjustment..............
Mistake #1: I completely misunderstood the mechanical arrangement of the lock-nut and adjuster mechanism. I thought the adjuster screw was the lock-nut and that the rod itself was the adjuster (it's got a a screw driver slot, right?). After rounding off the corners of the real adjuster screw's head, I thought I'd better try loosening the really big nut - at which point the real adjuster screw turned quite easily - duh!
Rounding the adjuster screws head distorted the round hole through which the rod must travel which resulted in the rod not being able to move freely at that end of its travel. To correct this, I ground a slight taper on the end of the rod to eliminate the interference. So far so good.
Had to take a break to take care of another task and had more than a few beers before getting back to the tune up
Mistake #2: Put the pieces of the adjuster mechanism back together in the wrong order and re-installed them. I feel so stupid, but I put the little rubber coated washer thing onto the rod first, then the spring, then the aduster screw. Put the whole mess back into the engine and started tightening. At some point past too far, I realized something wasn't right and started it back out. The spring had compressed until the coils were bound, and then simply began to distort as I had relentlessly kept wrenching on it. The rod and the smashed spring were all bound up in the cylinder head hole. With help from above, I managed to extract the mess from the hole using a thin screw driver and needle nosed pliers. The spring was rather distorted, but I managed to massage it back to a reasonable approximation of it's original shape. I reassembled everything in the proper order, set the adjustment per the book and had four days of uneventful commuting to work.
When I tried starting the bike after work on Thursday, the kick start lever would not move.....I thought to myself "how could the engine be frozen - it was running great when shut it off this morning". I double checked that the transmission was indeed in neutral and pushed a bit harder on the kick start lever. The lever moved a few inches and then would not spring back up. I pushed harder still and got a few more inches of movement but still no return. I shifted the transmission to top gear, pulled the clutch and pushed the bike and let go of the clutch to see if the engine's internals would move. They did. The kick start lever still had no return activity.
I put the transmission back into neutral and pushed the kickstart lever through it's full downward stroke by hand and then it came back up by itself (return spring now functional).
The bike then started and made the trip home. The shifting felt "notchy" though. I haven't ridden the bike since - I fear something internal broke when I tightened the incorrectly assembled cam chain tensioner and that pieces of it are now roaming freely through the bowels of the motor.
I'm in the process now draining the oil so as to check the filter and sump screen for debris. Will post later on the findings.
I am hoping one or more of the forums more knowledgeable can speculate on exactly what chain of unfortunate mechanical events occurred when I tightend the incorrectly assembled cam chain tensioner.
The effect on the rod assembly would be to have legthened it by the compressed height of the spring, thereby pushing on the adjuster lever with much more force than it was designed for.
Jerry
. Will take a couple of weeks to get here.
