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General Category => General Discussion => Topic started by: jerryS on July 07, 2026, 04:34:08 AM
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I'm taking apart my LM III to fix a few issues and I thought I'd pull the timing chain cover to make sure the tensioner etc were all good.. Well, look what I found:
(https://i.ibb.co/nNRkbdmp/20260707-140734.jpg) (https://ibb.co/nNRkbdmp)
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I guessing this is good news.
Can anyone tell me what aftermarket product this is and why it might have been installed. The bike has done 55k km and is pretty much original .. or so I thought. I got a box of bits with the bike .. which included the old timing chain and spockets and oil pump.. conspicuously no chain tensioner tho..
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Well yes.
They are an aftermarket fitment that reputedly contributes to more accurate timing and is more reliable over the long term.
I fitted a similar set a few years ago from Joe Caruso and although they fitted beautifully and gave no issues, I felt that they were too noisy, but not everyone agrees.
The bike was (and still is), a 1200 Norge.
Granted, mine were heat treated steel, not aluminium alloy so yours might be quieter.
Before…
(https://i.ibb.co/Vcz00kff/IMG-5442.png) (https://ibb.co/Vcz00kff)
After…
(https://i.ibb.co/k6h9MQ3L/IMG-5441.png) (https://ibb.co/k6h9MQ3L)
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Found the same when I opened up my LMI. Looks like they are from the same manufacturer. Nice improvement.
(https://i.ibb.co/wNKvHMB3/lemanstiminggears.png) (https://ibb.co/wNKvHMB3)
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I'd assume the crank gear is steel and the cam gear is aluminum. That's pretty much engineering standard in this application.
Sort of like wooden gears against metal gears in antique mechanisms that lasted forever.
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Agostini Timing gears. I have them in a few bikes. as long as you don't see any aluminum paste, you are golden. You may have an aftermarket cam in there! Good stuff.
(https://i.ibb.co/GQFm9fVT/20241213-160328.jpg) (https://ibb.co/GQFm9fVT)
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Thanks for all your comments.. Least I won't have to pull the timing cover off too often. :cool:
I did ride this bike for a year before the rebuild and I can't say I noticed excessive noise.. but I don't have a lot to compare against I guess.
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It’s often stated that a significant advantage of the gears is that they do not allow cam timing to drift with chain wear.
Well the crank sprocket rotates clockwise (viewed from the front) and pulls the cam sprocket anticlockwise as a result.
That short section of chain is about 50 mm long and the difference in a brand new or fully worn chain along that section might total…10 thou’ ?
The circumference of the cam sprocket is about 350 mm, so 10 thou’ or 0.25 mm is about a quarter of one degree cam rotation.
It is only that section of chain that determines the timing of the cam to the crank.
I admit I had mine in for a while, but it was just the dry screaming sound that I could not abide. They may have bedded in eventually, but it was just too much.
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The chain tensioner was the sliding type not a spring loaded type. Gears are all good as long as it's not from Harpers, they shred aluminum cause made from wrong type of aluminum. A customer bought a set & had aluminum in his oil. I put a set from Moto Int in it & all was good.