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Discussion Starter · #1 ·
Hello everyone. I have been the 3rd owner of this 73 cb350g for about 2 weeks now. I'm starting to learn the personality of this bike and think I'm looking at a few issues.

The engine seems to run great. Good power (for a 350). Revs good. Jetting seems perfect. All that good stuff. However, the engine sometimes (probably 50% of the time) makes a quite defined knocking sound. I don't really know where to start.

I have checked and adjusted the valve tappets. Loosened and retightened the cam chain tensioner and let it do it's thing. Set the ignition timing. Anyway, here's the kicker (maybe): I did all of this by setting the rotor at its alignment points and holding them with a c clamp because the engine would not stop at the marked points. It just wanted to roll past them. So I held it in place while doing the checks and adjustments where needed. (I only needed to adjust 1 valve to spec).

Is this horrible? Do I need to reset my cam chain position and is that the reason the engine won't stop at those points (and the cause of the knocking sound)? It seems weird but the engine idles and revs quite smoothly. So please, someone set me straight. I'm will to do whatever work is necessary to figure this out. I almost forgot: I also changed the oil but I don't yet have the oil filter tool so I cleaned everything I could get to as the owners manual said to. I plan to get the tool asap.
 

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First off, welcome to the group.

The problem with the crankshaft not wanting to stay in position on the timing marks is normal, compression in the cylinders makes it want to move. Folks have used vise grips, crescent wrenches, even hydraulic jacks to get it to stay in position and have not caused any problems (AFAIK).

The real experts will be along and help you diagnose your problems soon as you have found the ultimate fountain of knowledge when it comes to old Honda twins.
 

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Discussion Starter · #3 ·
That's great to know. I used a c-clamp on the wrench and header with a rag to protect the chrome.

So I went for about a 20 mile ride yesterday. And also invested in a mechanics stethoscope. When I pulled in after my ride. The ticks and knock type sounds were in full swing. So I used my new stethoscope to listen and it seems nothing sounds unusual around the mid to bottom of the cylinder or lower in the crankcase. The only noises seemed to be in the valve area. I guess I need to somehow determine if the level of noise is normal.

I have a(n ignorant) theory: I am still waiting for my oil filter tool to arrive. So really I've yet to perform a proper oil change with full filter removal and cleaning. The parts of the filter I was still able to clean were absolutely nasty and caked. I'm thinking the area behind the special nut could be just as bad. Could this effect the flow of oil engine to cause (random and somewhat inconsistent) noise up top?

Either way, I'm sure it couldn't hurt.
 

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I think these old motors make a bit of noise as a rule. They dont seem to be as quiet as the newer bikes you may be used to. If you have everything set correctly and you wear a helmet just pull the chin strap to get the helmet tighter against your ears and enough that you dont hear the nose anymore. Then enjoy the ride. :lol:
 

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Discussion Starter · #5 ·
While I'm at it here, are there any other parts of this engine that inherently need checked or replaced other than those mentioned. I honestly don't know the true mileage of this bike. I've had it 2 weeks. The odo reads 36K but the PO says when he bought the bike the speedo/odo was broken and he replaced it with this used unit. I thought "yeah right." Until closer inspection showed that the speedo is in a little worse shape than the tach. And here was the kicker, he had some parts he sent in the mail a few days after I bought it and in that package was a receipt for the speedo from a salvage yard.

So if I understand, theres also a rubber roller in the cam chain tensioner assy. that only lasts 25K miles? Is this something everyone should replace? Should I just wait until something goes wrong (not my style really)?

Yes I'm kinda used to a little less refined bikes than today's typical FI and ABS equipped machines. My daily driver is a Kawi KLR650 and I also own an 82 Suzuki GS1100G with vetter fairing and cases. So thats why I was wondering about the noises. Each bike in the fleet sings its own song. 'Specially the GS...
 
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