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Discussion Starter · #1 ·
I just freshly rebuilt this CB450 engine. New pistons and everything. The force needed to turn it over throughout the cycle changes dramatically. As it passes LT it gets very hard to turn later it gets very easy to turn. I attached a video in this link of me turning it over and am wondering if this looks correct. Video of Engine Turning Over
 

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You may as well pull the top off the motor and check the timing mark alignment, if it's off you may as well remove the head and check for bent valves.
 

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1963 Honda Dream 300
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I did a top end rebuild on a cb450, the machine shop charged extra to tear the head apart and put it back together after doing the valve job. I put the top end back on the engine and installed it into the frame. I checked the timing as well as my friend before coupling the timing chain. We got everything back together and put some gas in tank and hit the little magic button. Well it turned over to start and then really started spinning freely, nothing happened, pulled the plugs and no compression! We tore the tank back off and checked the timing again. Well low and behold, the machine shop mistook a casting mark on the cam for the timing mark as we did also for the timing mark. They installed the intake cam backwards, it bent the valves and ruined the valve guide’s. The casting mark and timing mark were hard to tell apart, pull the head. I bet the same thing just happened to you, please post you findings.
 
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