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Question re: cam timing

Old 02-22-2007, 05:56 AM
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Question Question re: cam timing

For those of you that have timed your cams - how did you mount the degree wheel on the crank? I was hoping not to have to remove the flywheel nut again but can't think of a solid way of mounting it otherwise. Any other solutions others have come up with?

thanks

bill
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Old 02-22-2007, 02:16 PM
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anybody?
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Old 02-22-2007, 02:28 PM
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Sorry mate, I simply used the factory timing marks to do mine.

I dunno anyone who would have done this, maybe RC996 & Rollingalong, but they have both left the forum now.

Someone might pop up yet!
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Old 02-22-2007, 03:02 PM
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thanks shayne
I attached it to my 17mm socket and put that onto the bolt. There is just a little play in that system and getting repeated measurements is difficult. With a piston stop I did confirm the timing marks were right on for TDC front and rear. But getting opening and closing measurements is where the slop becomes more of a factor.
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Old 02-23-2007, 08:16 AM
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I contrived something yesterday to solidly fix the wheel to a 17inch socket/breaker bar combination and was able to get reproducibly reliable readings to the degree. With just using the timing marks to set my stage I cams (which is how I originally installed them) the lobe centers were off from moriwaki spec. by about 4 degree intake (109 vs. 105.5) and 3 exhaust (105 vs. 108.5). That supposedly could alter performance quite a bit. I'll adjust them and we'll see.

bill
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Old 02-24-2007, 03:03 AM
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I have heard that gains can be made by doing this, but it would need to be accurate. I didn't do this myself, I just went by factory spec.

Be interesting to see how you go.
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Old 02-27-2007, 11:25 AM
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Originally Posted by cliby View Post
I contrived something yesterday to solidly fix the wheel to a 17inch socket/breaker bar combination and was able to get reproducibly reliable readings to the degree. With just using the timing marks to set my stage I cams (which is how I originally installed them) the lobe centers were off from moriwaki spec. by about 4 degree intake (109 vs. 105.5) and 3 exhaust (105 vs. 108.5). That supposedly could alter performance quite a bit. I'll adjust them and we'll see.

bill
Bill - How did you get a solid mount for the wheel? I'd think there would still be some slop in the socket itself....?
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Old 02-27-2007, 01:49 PM
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Bolt's work great. You can thread two nuts on the bolt. One is to lock the bolt against the crank and would be used to turn the engine over. The other locks the degree wheel to the head of the bolt and can be loosened to get the wheel set up. The hardest part is finding a nut that is the correct pitch. I usually dig through a drawer of nuts-and-bolts but sometimes you have to resort to making them.

I don't know if this helps!
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Old 02-27-2007, 05:03 PM
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I removed the flywheel bolt. It's easy if you have the side covers off. A shop rag will jam the primary drive gears.

I made a stop like yours with a spark plug. Broke the tip off and turned a SHCS head down to fit tight in the hole. Then turned the engine forward and backward to and centered TDC between the two stops. A slightly more accurate way is to use a dial indicator through the spark plug hole.

Did you deck your heads? Must have to have the cam timing off that much.
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Old 02-27-2007, 05:56 PM
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thanks guys those were helpful suggestions - I was finally able to get reliable readings - always going in the counterclockwise direction helped of course. actually the readings were from a head that wasn't decked - I was suprised they were off by that much as well.

bill
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Old 02-28-2007, 07:46 AM
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Something's fishy.
I can't believe those cams are off by that much, unless you have slotted the mounting holes in the cam gears already.
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Old 02-28-2007, 02:50 PM
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I triple checked everything - and checked them prior to putting on the slotted cams. Before checking all the sprocket cam index marks lined up as expected using the flywheel timing marks. However, I found both front and rear timing marks on the flywheel to be off from my calculated TDC so it seemed to make sense to me. How much are you used to seeing the stock timing marks to be off by? If you have another idea of what to check please let me know.

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Old 02-28-2007, 04:55 PM
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The cams were both retarded by about 3.5 degrees.
If the cam gears have a 1.5" radius (approx.), that's about .090"
Seems like a lot. I doubt the cam chains are stretched that much, but I would check them. It almost sounds like you could be off by one tooth.

How are you checking lobe centers?
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Old 02-28-2007, 07:16 PM
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I checked them at 1mm lift for opening and closing measurements after adjusting the valves to spec. Always rotating forward and always being sure the dial returns completely to zero and moves throughout the range (and then just followed the standard formulas for calculating the midpoint - I've been assuming these are symmetrical lobes). After adjusting the actual opening/closing specs. matched what came with the moriwaki cams also.

I thought about being off by a tooth also - I even moved it one tooth and rechecked but that actually moves things quite a bit more than 3 degrees ( I can't recall - maybe 10+). I checked the cam chains and the appeared fine when I rebuilt (I think I actually bought relatively new CCTs from you maybe, and you sent chains also - same length all around).

I thought the cam moved at a 1:2 ratio with the crank, so that 3.5 degrees is 1.75 degrees of cam and using the estimated radius of 1.5" = 0.045". Is that correct? Has anyone else checked their stock timing before slotting the sprockets to know by comparison?

thanks for the input by the way. I appreciate the help and learning something.

bill
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Old 03-01-2007, 07:45 AM
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I was just coming here to say that. Yes, about .045".
I don't know how many chain links there are from the crank to the cam gears, but that would equate to something like .001" per chain pin, so you may just be seeing the effect of a stretched timing chain. It will probably run fine after you degree the cams. I don't know what the service limit is for the chain.

I think you have my chains, right? They had about 30k miles on them. People run them a lot longer than that.
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Old 03-01-2007, 09:45 AM
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Although, if it were me and I was planning to race the bike, I would be looking in to replacing the chains.
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Old 03-01-2007, 09:55 AM
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thanks. I compared yours to the ones in the motor (had about 13K miles on it) and they were the same length. The manual doesn't specify a service length limit on them so there wasn't much else to compare to. but beyond that, I think the discrepancy I'm getting is the timing mark on the flywheel is just off from TDC when checked with a piston stop/degree wheel. So the stock cam index marks when set to that timing mark are off the same amount. I can double check TDC with a dial indicator also to be sure I didn't screw up there. I'm out of town for a week so has to wait till I return.
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