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Post by ash13brook on Jun 30, 2014 10:12:39 GMT -5
I'm putting my top end back together.
In the tear down process, one end of my cam chain got away from me and I had to remove it completely. I got a piece of string back around the crank so I can string the new chain through.
What's my best course of action for completing the cam chain installation and are there any tricks you might pass on to me for this job so I get the valve timing correct the first time.
Also, I ordered a couple of extra master links for the cam chain in case I do have to move the chain a tooth, but they do not have the hollowed copper colored ends where they are peened. They just look like solid steel. Any idea how to peen these without the special tool?
Thanks,
Matt
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Post by motormike on Jul 1, 2014 6:08:16 GMT -5
what yr is the engine.... could you remove the bottom oil sump cover.. it should give you a visual on the chain to aid installation.... drop a string down and roll the chain up. If you have a master link pin punch tool from Mikes it works... I have used a LARGE bolt cutter... as in a 3 footer.. small bolt cutters won't open enough for a good " bite ".. a LARGE one does and provides a good pinch. there's a notch on the cam... ck the book.. it should be on the left side at 12 o'clock and the " dot " on the cam level with the head.. again ck the book... once the chain has the master link installed.. if you need to make a adjustment.. you can loosen the chain adjuster.. slide the cam bearings off ..lower the cam enough to rotate for adjustment.. slide bearings back on .. double.. triple ck... make sure bearings are all the way on... otherwise the seals can't be seated properly... I use Yamaha bond for the valve cover...  only on early Xs units do you have to open the cam chain. |
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Post by ash13brook on Jul 1, 2014 20:56:39 GMT -5
It's a 72. Thanks. That should get me started.
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Post by grizld1 on Jul 2, 2014 8:44:57 GMT -5
The easiest way to check camshaft installation is this. Jam fit a line in the hole in the left end of the crankshaft, using a wood dowel, bamboo barbecue skewer, or anything else that occurs to you. With the cam chain adjuster installed, pistons at TDC, and the timing notch in the camshaft at the top, pull the line up across the center of the camshaft and sight on the timing notch. The line should be exactly centered on and run parallel to the notch. Do the inspection with only one bearing installed on each end of the camshaft; that makes things easier if you need to drop and move the camshaft.
After you've installed and fully seated the bearings, make sure that the camshaft is centered. Use the depth probe of a caliper to measure from each outer bearing to the edge of its journal, and make sure the measurement is the same on both sides.
Re. the master link, the riveting tool from Mike's XS works very well; but mine was bought years ago, and I don't know what they're selling currently. An alternative is to have a helper back up the link with a maul or other flat heavy object while you peen down the pins with a hammer and punch.
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Post by ash13brook on Jul 6, 2014 18:41:50 GMT -5
So...
I wrestled my cam chain on. Adjusted the cam chain tensioner and valves to .012, and set up my dial indicator on the left intake valve.
I used a compass rose that I printed from a navigation course I took and taped it on my alternator(I have the permanent magnet alternator). Found my TDC and rigged up a pointer to 0 degrees. Bolted the rocker box down and turned the alternator. The valve started moving immediately. Head scratching and sighing.
Rocker box off. No idea so I wrestle the bearings off the cam and move it one tooth clockwise...just because I had no other ideas. Did everything again. This time the valve started moving about 11 degrees too late. Head scratching and sighing. Maybe a beer will help. Looking at both manuals, I see the sprocket on the crank is half the one on the cam. Eur-f----ing-eka.
Rocker box off again. Bearings wrestled off cam again. Sprocket moved back to original position with help of, by this time, a very sympathetic wife.
Timing right on this time.
More beer.
I really appreciate everyone's help. I went over my last two posts about a dozen times, as much for moral support as anything.
Matt
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Post by grizld1 on Jul 6, 2014 22:38:21 GMT -5
Good work, Matt! And you learned something important--in any 4-stroke motor, the camshaft has to turn at 1/2 crank speed; that's how you get the valves closing on one upstroke (compression) and downstroke (power) and doing different things on the next upstroke (exhaust) and downstroke (intake).
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Post by Phantom Phyxer on Jun 20, 2015 9:59:30 GMT -5
Hi, will the engine run and can it be timed if the valve timing was off by 1 tooth on the camshaft?
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Post by Phantom Phyxer on Jun 20, 2015 10:06:57 GMT -5
Hi everyone. Got a question; Would the engine run and could it be timed if the timing was off by 1 tooth in either direction?
Thanks.
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Post by grizld1 on Jun 21, 2015 20:29:38 GMT -5
No. Late cams have 36 tooth sprockets geared 2:1 to the crank, so 1 tooth=20* of crank rotation, and while the motor may fire erratically off the starter, it won't run with that much error in valve timing. Early motors have a 34/17 combination, so even greater error results.
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Post by Phantom Phyxer on Jun 25, 2015 17:16:24 GMT -5
Cool, I thought as much. I think my timing chain must be stretched a bit cause with the PAMCO ignition on this engine, I have to move the plate quite a ways counterclockwise to get it to line up on the timing mark. It advances OK and runs OK but I was just wondering if I could have been off a tooth when I installed the cam. My other engine works with the plate petty near centered. 650s Rock!
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Post by grizld1 on Jun 25, 2015 18:31:09 GMT -5
Right you are. As the cam chain wears, the tensioner pulls the camshaft to an increasingly retarded position, and if the ignition is camshaft driven, ignition timing must be advanced to compensate.
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only on early Xs units do you have to open the cam chain. 
