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Discussion Starter · #1 ·
I am working on a 1973 Honda Cb350g. The engine seems to be running with the timing retarded. It seems the engine is getting hot quickly, and the engine in running sluggishly. I have timed the engine according the book. I also checked the exhaust for any obstructions. I have also rebuilt the carbs and have no issues. What are some other areas to check?
 

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Make sure the timing advance isn't getting hung up. If I remember correctly, there isn't much clearance behind the point plates and it's easy for them to stick and drag.
 

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Check the advance with a timing light; it should advance smoothly from the set marks to second set of marks for full advance, with full advance reached at about 3500 rpm. It is common for the advance mechanism springs to be loose their pins, making for reduced advance, or the cam sticks, causing no advance when the weights try to move it.
 

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Aren't they air cooled? just FYI, air cooled bikes -will- heat up pretty fast if they aren't moving, so it would be important for us (or me at least) to know specifically how hot it is getting and how "quickly". (and how long you've had it and if it has always done that, or if it is a recent development, that way i know what you're comparing it to) as for running sluggishly, it could be timing, could also be that you need a valve job, or that the carbs need work, or various other things. it's hard to pinpoint things on an old bike, trust me on that lol
 

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Aren't they air cooled? just FYI, air cooled bikes -will- heat up pretty fast if they aren't moving, so it would be important for us (or me at least) to know specifically how hot it is getting and how "quickly". (and how long you've had it and if it has always done that, or if it is a recent development, that way i know what you're comparing it to) as for running sluggishly, it could be timing, could also be that you need a valve job, or that the carbs need work, or various other things. it's hard to pinpoint things on an old bike, trust me on that lol
+1

My first thought was fuel mixture. Too lean = too hot.
 

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A few things can make it run hot. Is the exhaust original? If someone put a different set on and didn't rejet it could cause it to overheat. Someone could have put in the wrong plugs. They should be B8ES (NGK). It could have the wrong set of carbs on it or jets in it; the 350 was outfitted with several different carb models. Have you adjusted the valve clearances?

Cheers,

Mike
 

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Discussion Starter · #7 ·
For the timing advance, it where the arrow is pointed, is that supposed to turn in there. I guess what I'm asking, does the copper piece move, or does it move around something?

I have re done the valves and also taken the carbuerators apart and cleaned them. Also the exhausts are original and not plugged.
 

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The outer cam should move, relative to the copper-colored piece, when the weights are pulled outwards by centripetal force. When on the engine, the center piece is bolted to the camshaft, so the cam actually moves relative to the camshaft. It is the cam which lifts the points, so as it rotates CCW relative to the camshaft, the timing advances.
 

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Discussion Starter · #9 ·
WintrSol- The outer cam deffinitly did not move around the copper piece. I have been soaking it in PB blaster and nothing worked, so today I heated it up and it broke free. I got it cleaned up, put it back in the bike, and now it runs a hole lot better. I still have some carb issues, but that piece was deffintly the problem. Thanks for the help.
 

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:thumbsup: Now that's settled, you can get it properly warmed up, and look at the carbs. Getting a good sync is a real pain without vacuum ports, but really helps a twin. I have a spare set of manifold boots, which I modified to add ports. Not reliable for normal use, so I (carefully) replace the other set, once a sync is done.
 
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