Author Topic: Timing Chain/sprocket Replacement  (Read 227 times)

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Offline MSRev

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Timing Chain/sprocket Replacement
« on: May 16, 2018, 03:00:26 pm »
Does anyone know of a good video to help me with this adventure? Connie has 102K and while I am adjusting the valves and replacing the water pump now would be a good time to get the chain and sprockets replaced.

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Offline MAN OF BLUES

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Re: Timing Chain/sprocket Replacement
« Reply #1 on: May 16, 2018, 07:07:55 pm »
Not sure if SISF did one on that, but beforehand have you done the "link count vs length" chain measurement, and do you see excessive wear on the gears? The gears are pretty durable, so if the chain measurement excedes spec, maybe just need the chain only.
FSM specs a dimension from a pin on a link (let's call that link #1), to the same pin on #20 link...
Problem is, the camshafts are spaced approx 5.38" center to center which is less than the dimension you are shooting for, (placing the links by count, outwards on the gears), and as such, forces you to remove the chain to measure it correctly.. big bummer.... and with the chain removed, you have to put about 10 pounds of "stretch pressure" during the measurement...in a straight line, another bummer...  so you can't do the 20 link thing while its on the bike....
The 20 link pin distance when removed is 6.252" to 6.268" normal/ok.  And replace when 6.358" is reached...

But modern math to the rescue.... you CAN measure 16 full links while mounted...
When checking chain stretch, I do it in a couple places, manually rotating the engine during the process, with the spark plugs removed...(much less resistance to rotate)
Remove the upper cam chain guard, and "bump" the chain tight by turning the rear wheel with bike in gear...
Measure from a pin on link #1 on top of gear, to same pin on link #16 on the other gear, in a straight line...
Normal is 5.002" to 5.014". And if the dimension is 5.086" or greater, it should be replaced...
As I noted, do this multiple places on the chain, by rotating the engine manually.
Hope this helps...
« Last Edit: May 17, 2018, 09:49:14 pm by MAN OF BLUES »

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Offline mr t

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Re: Timing Chain/sprocket Replacement
« Reply #2 on: May 17, 2018, 12:21:39 pm »
Very clever solution MOB.

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