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Timing Advance sticking

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G-Man
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Re: Advancer rebuild

Post by G-Man » Tue Mar 17, 2015 6:17 pm

I built my own timing light when I was a student, from a design in one of the electronic magazines. I used it on everything, cars and bikes. Wouldn't be without one.

G
Tim Miller wrote:Larry,

Unfortunately the advancer should come out. No stops were available from honda. I machine my on and change the timing curve. It's well worth the effort. It's nice to hear someone using a TIMING LIGHT!

Tim
redblk63 wrote:Similar question. Is it possible to replace the maximum timing stop (made from rubber?) after removing the top cover, but without removing the camshaft? My motor serial # is cb77e-1005392, which may be a 1965 model.

Is the "stop" an available part? Does anyone have a picture of how it should look in place?

My problem is when I set the correct static timing, the maximum advance is about 10 degrees too much. I have backed if off to be correct at maximum advance to keep the engine safe, but as you can imagine, the off-idle response is pathetic.

Larry
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
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redblk63
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Post by redblk63 » Wed Mar 18, 2015 2:00 pm

Tim,

Take it out, eh. I figured as much, and I knew you'd done this advancer rehab before.

I usually just do static timing, but resorted to my timing light to check full advance after seizing in the Mojave desert heat on last year's Death Valley ride. (This year, I rode my CT90 to Death Valley and back with no problems.) I am now a convert to using the timing light on the engines I care about, which coincidentally also have a lot of mileage and wear.

I did find some pretty good pictures of the advance mechanism on another thread, to remind myself what it looks like. Also, someone posted that the bob weight pin sleeve thickness was about 1.8 mm, so I will try to find something like that.

Do you, or anyone else here, have a pair of sleeves to sell, or a machinist sketch of the needed parts?

I assume the goal is to have the springs tight when the cam is static, and to allow for advance from the F mark to between the full-advance hashes. The adjustment I can change is to make the sleeve thinner/thicker to get more/less advance between idle and high-speed.

I am not too worried about the advance curve vs RPM between idle and full advance, as I do not expect to spend much quality time below 3,000 RPM. This rehab is not critical. It will just gain me a better off-idle response, since I am already timed correctly above 3,000 RPM.

Sorry for adding my questions to this thread.

Thanks for the help,
Larry

Tim Miller
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Post by Tim Miller » Wed Mar 18, 2015 10:51 pm

I usually make 10mm stops for my rebuilds to give 12 initial & 42 total.


Tim
redblk63 wrote:Tim,

Take it out, eh. I figured as much, and I knew you'd done this advancer rehab before.

I usually just do static timing, but resorted to my timing light to check full advance after seizing in the Mojave desert heat on last year's Death Valley ride. (This year, I rode my CT90 to Death Valley and back with no problems.) I am now a convert to using the timing light on the engines I care about, which coincidentally also have a lot of mileage and wear.

I did find some pretty good pictures of the advance mechanism on another thread, to remind myself what it looks like. Also, someone posted that the bob weight pin sleeve thickness was about 1.8 mm, so I will try to find something like that.

Do you, or anyone else here, have a pair of sleeves to sell, or a machinist sketch of the needed parts?

I assume the goal is to have the springs tight when the cam is static, and to allow for advance from the F mark to between the full-advance hashes. The adjustment I can change is to make the sleeve thinner/thicker to get more/less advance between idle and high-speed.

I am not too worried about the advance curve vs RPM between idle and full advance, as I do not expect to spend much quality time below 3,000 RPM. This rehab is not critical. It will just gain me a better off-idle response, since I am already timed correctly above 3,000 RPM.

Sorry for adding my questions to this thread.

Thanks for the help,
Larry

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