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Discussion Starter · #1 ·
After all the reading that I have been doing on here while resurrecting my 73 cb350g, I am growing concerned about the age of the cam chain and tensioner wheels. 16,000 miles and 45 years probably hasnt been kind to them.
My thinking is that I will just replace it.
Are these replaceable without taking the engine apart? From looking at the manual diagram that I have, i'm concerned about taking the tensioner off and the chain slipping on the sprockets.
Are these interference engines? Do I need to do this asap? or maybe stop worrying and ride my bike?

I dont notice any unusual noise

thanks everybody
 

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It's a top end rebuild to replace.
When you start seeing rubber and/aluminum shavings in your oil, or the engine gets loud and rumbly, then you know times up.
I'm currently on an engine with crusty rollers and it seems to be holding on okay.
Enjoy the bike and keep the tensioner adjusted
 

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The center cam chain roller and tensioner roller are not replaceable without disassembling the top end of the engine, which requires the engine to be removed from the frame. You could inspect the tensioner roller condition by removing the tensioner assembly from the back of the cylinders, but you'd probably need to get the carbs out of the way to see much of it through the opening. All Honda twins are interference engines, a tooth or two off will bend valves. If the top end noise is fairly quiet and you keep the chain adjusted properly, then you'd just keep your ear on it and watch for rubber fragments in the oil filter during oil changes for indications of excess wear
 

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Most cam chains are of the closed/continuous type and when you buy a closed cam chain, you also have to split the bottom cases. You can also buy a chain and a rivet link and then you do not have to split the bottom cases. Some people find rivet links dangerous but I never had any problems with them. Depends on how good your riveting is.

I agree with 540Nova that 16k is not that much for a cam chain, especially if it was maintained properly and tensioned correctly. But the tensioner wheels will most definitely have hardened over time so I would definitely change those out (or at least look at them). You can easily look at them by removing the tensioner.
 

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Discussion Starter · #6 ·
I think I'll pull the tensioner off and make sure that things aren't hanging by a thread. If it appears ok I'll ride on.
Thanks everyone for the quick replys.

Just didn't want to take a perfectly good engine and ruin it.
 

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Having pulled apart 15 to 20 of these engines I have never found a good set of original tension rollers. Some worn excessively or chunked and all have been very hard with no flexibility left.

Also as the wheels wear down or get serious grooves and especially if cam chain tension has been poorly maintained then wear occurs on the pivot assembly and engine case. As the wheels wear the chain also tends to run to one side.

As has been pointed out this is major work and more usually needs to be done than anticipated. I would anticipate with your engine having 16000 miles, unless you know a lot of the bikes history of maintenance, that you would be looking at a cylinder bore, new pistons with rings, valve job, probably new valves ... intakes are usually the most worn, guides and probably some valve spring replacements. This in addition to gaskets and seals and the timing chain with rollers etc.

Budget a thousand and be happy if it's less.
 
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