Primary Chain


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bikeymikey748
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Primary Chain

Post by bikeymikey748 »

‘Morning folks.
I’ll be on the north side of 100,000km. by the time the snows come again.
Planning on replacing my cam chains, valve seals (used aftermarket ones when I did my build, looking at viton replacements), as well as crank and con rod bearings.
I was wondering what the consensus was regarding primary chains. Specifically, should I consider replacing mine when the motor is open? There’s no unusual noise, and no markings on the oil spray bar. Are they long-lived?

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NobleHops
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Re: Primary Chain

Post by NobleHops »

Mike, I personally think you’ll find you need a large cam chain tensioner before you need crank or rod bearings, but you’ll know when the plastigauge is employed.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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bikeymikey748
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Re: Primary Chain

Post by bikeymikey748 »

Thanks for chiming in Nils. When I did my build I replaced my ‘A’ tensioner with a new (reconditioned) one, is that what you’re referring to? I know the adjuster for the ‘B’ chain is pretty much maxed out though 🥺. As that tensioner was replaced with a new OEM one during the build as well I’m guessing the chain is roached. Figured the crank and rod bearings, as you mentioned, will get a check with plastigauge but I would expect they might need a refresh at this point, no? I’m into the upper range of my revs on a fairly regular basis and between that and looking down the barrel of another looming Canadian winter figured it would be a perfect time to dive into the motor and secure some peace of mind for next few years. I had fitted aftermarket valve guide oil seals and plan on replacing them with viton bits. I’ll McGyver a tool to do them without removing the head. Scored some oversized Oldham couplings from Bert at Six Center too. Looking forward to seeing how well they work out.

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NobleHops
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Re: Primary Chain

Post by NobleHops »

Personally I would not replace those bearings wholesale if they measure in spec and there's no evidence of smearing or transfer of the bearing material.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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bikeymikey748
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Re: Primary Chain

Post by bikeymikey748 »

“Personally I would not replace those bearings wholesale if they measure in spec and there's no evidence of smearing or transfer of the bearing material.”.
Absolutely. I just HAVE to have a look though 😉

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bobcat
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Re: Primary Chain

Post by bobcat »

There would be no question in my mind about replacing the primary chain while you have the motor
that far apart. With that many miles and "upper RPM range" frequent use and maxed out cam chains,
why take the chance. There is no unusual noise until suddenly there IS ! It will do a lot more damage
than just a broken chain. My 2 cents..

...and don't skimp on quality by buying the cheapest one. Suggest Borg Warner (Morse).
Bob
82 CBX, 81 CBX, CB1100F, 79/82 CB900F (avatar)

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