So I took apart the topend on my 2005 Honda 450r because something was knocking pretty badly we think it was a rocker arm.I was putting it back together and I had the head on and tryed to turn over the motor and it would go not even half way and now it won’t even go halfway was wondering if y’all would know
Make sure that the Timing Chain is not bunched up behing the Fly Wheel. Also make sure that the Timing is set right and the the Valves are not hitting the Piston. Do not force it to go more if it feels "locked" because for 1 if the Timing chain is bunched up it can break the Timing Chain Guide holder which is a cased part of the left crank case I see it so much too. If that part does become broken from the chain bunching up you need to know a really good TIG welder or get a whole new left Case.
What i would do is ensure that your timing is correct, if it is then Try to rotate the engine back wards while yanking up on the Timing Chain till you get more timing chain slack.
As @Ryan94Wright said, double and triple check its not the timing chain. Sometimes if it gets bunched up, even if you pull on it, it stays wedged down in there. He best way to make sure it’s not the chain is to put the chain on the sprocket and the sprocket on the chain. If it reaches, chained not bunched up, if it doesn’t, chain bunched up. Maybe you already did that.
The other likely culprit is a bad crank. Signs of a bad crank or rod bearing are spinning free then suddenly catching and locking up.
Or again, as Ryan said, valves could be hitting if timing is off.
So I took the flywheel out and removed the timing chain and still won’t spin over so definitely not the cam chain something is stopping the crank it would spin over but it locked up the more I spun it over and now it will barley move
Maybe its time to bring it to a shop with a certified honda tech. Dont take it personally, im sure you know what you’re doing, but sometimes its best to throw in the towel and let someone else take a look. Hope you figure it out
My guess is that the Timing is off and the Valves and piston are stuck against each other.
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