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Discussion Starter #1
I was trying to check and adjust the tappet clearance on my CB500T (the first time I'd done it on this bike) and ran into a couple of issues:

- The manual I have says to line up the LT mark with the index mark of the case, make sure that the reference mark on both cams doesn't line up with the index mark on the cam bearing holder, and insert a .0012" feeler gauge between the cam lobe and the tappet. However, even when the marks are lined up properly, I can't get enough clearance with the adjuster to slide a feeler gauge all the way in there at all. Am I missing something? I read the remark about the camshaft marks to mean that it was OK if one was lined up, which it was in this case, and it was only a problem if both were. Should it actually be that neither cam should line up?

- As part of trying to figure this out, I decided to spin the motor again and see if the marks on the cams lined up with the mark on the bearing holder. My manual said to turn the rotor counterclockwise, but the bolt in the center of the rotor is a right-handed thread and eventually the bolt spun loose. I'm hesitant to try and wedge something in between the rotor and the case to hold it tight, because I have broken things that way before. Any suggestions on how to get it fully tight, and, once I do, is it a problem to spin the rotor clockwise to line up the timing marks?
 

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To start, what manual are you using? If it's anything but the Honda service manual, I would not trust it. If so download the Honda FSM instead

Also you should remove the spark plugs when you do this so that it would make turning then engine over easier.
 

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Not sure which manual you're using (as asked above), but here is how you do it: turn the engine over until you see the left cylinder intake valve open, then close, and right after that you watch for LT. That means the left cylinder is on compression stroke and both valves are closed. To be sure we're talking about the same things here, you put the feeler gauge between the cam follower and the cam lobe - not between the end of the follower and the tip of the valve like on other engines. If the alternator rotor bolt came loose during proper engine rotation, you need to tighten the rotor bolt. Use you use either an electric or air impact carefully, you can tighten the bolt without worrying about holding the rotor still. If you don't have an impact, put the engine in 2nd or 3rd gear and have someone hold the rear brake pedal firmly when you tighten the rotor bolt. If you don't have the FSM, you can download it here
 

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Discussion Starter #6
My manual is a "Cycleserv", but apparently it's just a reprint of the FSM. :ROFLMAO: (Although mine doesn't have the NOTE: at the bottom of page 1, it just goes straight to the points adjustment.)
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Discussion Starter #7
you put the feeler gauge between the cam follower and the cam lobe - not between the end of the follower and the tip of the valve like on other engines
That's what I was doing, but I was wondering if it was right. Should the feeler gauge be able to slide all the way through? I couldn't find any spot on the adjuster where it could fully get through there.
 

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If you're sure you're on the right stroke, part of the problem could be the thickness of the feeler gauge - .0012" is really thin and difficult to push into a gap without flexing. We used feeler stock back when I worked at the Honda dealers, and we'd use our thumbnail to pull/bend a "curve" into the end of it so we could slip it around the cam, and then use the feeler looped around the camshaft holding both ends to slide it in between the lobe and follower. The usual problem with these engines (when not properly taken care of) is excess wear on the followers causing a lack of enough adjustment to achieve proper gap (IOW, too loose) and not the other way around. Make sure your follower shafts are properly oriented as shown in the picture above showing the index mark pointing outward toward the front and back of the engine, not inward, and if you still can't get the feeler in between, then the only thing left is that the valve has sunk into the head more than typical from aging (or the engine was rebuilt not long ago and the valve seats cut excessively) causing a loss of adjustment range
 

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Discussion Starter #9
Long story short, at some point somebody replaced the rotor setting bolt in this bike with a regular hex head bolt and some kind of washer with a shoulder. Trying to torque it down twisted the washer apart (which was probably why it spun loose relatively easily in the first place) so I need a better solution. Actual rotor setting bolts are rare and pricey, has anyone ever had luck using a flange bolt and a washer or two instead?
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Discussion Starter #12
Not hardened, but a M8 flange bolt and fender washer seem to fit well. I still haven't got everything put back together, so easy enough to swap out for hardened if really necessary.

When I originally posted this, I had missed the fact that there's a pinned thread about valve adjustment on these bikes in this forum. I read through it all, and I've still got a couple of questions:

- I'm pretty sure at least a couple of adjusters have turned more than the recommended 180* range while I've been fooling around with this. As long as I get the perpendicular marks on the adjusters lined back up properly (pointing away from the head), is that going to take care of it?

- I feel pretty good about the clearances I finally got on the left cylinder (pending the above about the marks on the adjusters), but when spinning the rotor to try and do the right side the T mark keeps popping slightly past the index mark on the case. Do I have to have somebody hold it in place exactly with the line while I'm doing the adjustment, or should I do it where it comes to rest?
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On your first point, as long as the "pointer" marks on the adjuster shafts are pointing outward when you're done adjusting the valves, you'll be fine. This is the cutaway side view of what is inside. #2 is the eccentric adjuster shaft. From this, you can see how the follower would be moved backward, both away from the tip of the valve and not properly positioned under the cam lobe, if the index marks are pointing the wrong way. As for holding the engine at EXACTLY right side top dead center (T), it's okay if it drifts away a bit, it won't cause any harm. Just be sure it's as close to T as possible
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....Mild steel washers with only the slight overlap WILL "cup" inwards and loosen,possibly damaging the internal threads......The correct ($12) bolt pushes/clamps against the rotor's steel core, "bridging" the internal threading, and are hardened.....
You MAY be alright IF the bolt head does not touch the inner side of the round alternator cover......
 

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Discussion Starter #16
You MAY be alright IF the bolt head does not touch the inner side of the round alternator cover......
As always, the devil is in the details...the bolt head hitting the alternator cover is exactly what ended up happening. I have a '72 CL350 that's patiently awaiting some attention and found out they use the same rotor setting bolt, so I robbed Peter to pay Paul; the OD of the fender washer is the same as the OEM bolt, but the flange bolt head and washer together are a whopping 1mm thicker than OEM and that was enough to cause interference. The OEM bolt is also dished out in the center, which I guess is to sit in the nipple cast into the cover. Anyway, I'm going to use the bolt out of the 350, and then when I get back to that bike I'll have to deal with it then.
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So why can't you grind off a bit at the end so that the bolt will fit? That's what I'd do.
 

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Discussion Starter #18
Well, that's probably going to be my first attempt when I get to the 350, but a) it is in fact a hardened bolt, and b) I think the dimple is going to be a pain to try and carve out, above and beyond just taking some off the top of the entire head. (Assuming the clearances are as tight on the 350, I don't know for sure if they are or not. It was already disassembled.)
 

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The "dish" in the center of that bolt was so the Honda mechanic could use a rubber tipped mechanical tachometer on the crankshaft, and isn't critical......The "nipple" in the cover can be CAREFULLY pared down flush......Grind down the bolt head, and double-up the cover gasket......

WHY the black silicone sealer?....That is a NO NO!......ANYWHERE you have used it on this engine MUST come back apart.....and it ALL must be cleaned out/off.......
 

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I was trying to check and adjust the tappet clearance on my CB500T (the first time I'd done it on this bike) and ran into a couple of issues:

Am I missing something? I read the remark about the camshaft marks to mean that it was OK if one was lined up, which it was in this case, and it was only a problem if both were. Should it actually be that neither cam should line up?

- Any suggestions on how to get it fully tight, and, once I do, is it a problem to spin the rotor clockwise to line up the timing marks?
The PROBLEM here is that the cam index marks SHOULD ALWAYS BOTH align at the same time... BOTH camshafts spin at the same rotational speed.... IF YOU CAN ALIGN ONLY ONE WITHOUT THE OTHER, YOUR CAM TIMING IS OFF........

You spin the crankshaft ONLY CCW so the "pull" of the camchain is tight between cams and crank.....This places any chain slack in the back of the engine where it can be removed by the tensioner (if working and properly adjusted)....
 
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