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Discussion Starter · #1 ·
My gaskets were leaking oil pretty bad so over the winter so I took down the heads and replaced them, honed the cylinders, replaced the rings and put it all back together (per manual instruction). Its running great, but now I'm getting A TON of valve chatter. I have adjusted the gaps about 4 or 5 times now to no avail. Every time I check them after running the motor, the adjustments seem to be off. I do make all adjustments with at top dead center. Am I completely missing something? I'm doing .004 in and .006 out.

Thanks gang!
 

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What bike? For the 360 it’s .002” in and .003” out. You may want to check your clearance values against the FSM, doubling it would cause some chatter :D
 

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Are you turning the engine counter clockwise one revolution after adjusting one side then adjusting the other?
 

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Valve adjustment is done dead cold, anything else is a waste of time. If you've been doing the adjustments cold then that's good.
If so are the clearances looser than before? If so then there's a wear issue going on which could be the cam, rocker arm cam pad, rocker arm shaft bushing or the adjuster screw.
If they are tighter then you're looking at the valves seating into the head, possibly if the valves were refaced it'll need new valves.
 

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Discussion Starter · #5 ·
Are you turning the engine counter clockwise one revolution after adjusting one side then adjusting the other?
I have not been doing that. I have been adjusting both on one turn and line up with the T. I'll try this and see if it helps.

As for wear, everything should be in order as there was not chatter before I took it apart. Also, its the 400 engine on a '80 CM. Forgot to mention.
 

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I have not been doing that. I have been adjusting both on one turn and line up with the T. I'll try this and see if it helps.

As for wear, everything should be in order as there was not chatter before I took it apart. Also, its the 400 engine on a '80 CM. Forgot to mention.
Yup, you have to adjust one side, rotate, then adjust the other at TDC.


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TDC at the firing stroke, right? Watch the intake valve, it goes down(open) then back up(closed) as you turn the crank to TDC. Adjusting the valves at TDC on the exhaust stroke will make a lot of noise.
 
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TDC at the firing stroke, right? Watch the intake valve, it goes down(open) then back up(closed) as you turn the crank to TDC. Adjusting the valves at TDC on the exhaust stroke will make a lot of noise.
Since this is a 360 crankshaft design on TDC both cylinders are at TDC on the T mark. One side is one the ignition stroke and the other is on the intake stroke. You adjust the ignition side, valves are loose, then rotate the crank 1 revolution and adjust the opposite side.
 

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Another way to do it, on a 360° crank, is to turn the engine over until you see the valve rocker all the way down(valve open) and adjust the valve on the opposite cylinder. Turn it until that rocker is down and repeat on the other side. That's how we did it on Triumphs and BSAs back in the dark ages, no need to find TDC marks.
 

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Does this apply to the Honda CB450Sc also, My shop manual fails to mention this. which would explain why the right side valves seemed super tight and my left side was just a little out of adjustment. I have lined everything up with the T on the fly wheel so I would adjust one side then crank one full revelution and adjust the other side?
 

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Yes, this applies to all of the SOHC 400/450 twins.
There is actually a notch on the left end of the cam. As you can see in this picture when the notch is at the top the left cam lobes are up which means the valves are opening/closing. This translates to the right side being adjusted when in this position. One full crank rotation will move the cam 1/2 revolution so the notch is now down and the left side can be adjusted. Valves are only adjusted dead cold and the rotor on the T mark.
Auto part Engine Transmission part Gear
 

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Since this is a 360 crankshaft design on TDC both cylinders are at TDC on the T mark. One side is one the ignition stroke and the other is on the intake stroke. You adjust the ignition side, valves are loose, then rotate the crank 1 revolution and adjust the opposite side.
Another way to do it, on a 360° crank, is to turn the engine over until you see the valve rocker all the way down(valve open) and adjust the valve on the opposite cylinder. Turn it until that rocker is down and repeat on the other side. That's how we did it on Triumphs and BSAs back in the dark ages, no need to find TDC marks.
I went and done this and sure enough the Honda CB450SC you have to rotate the motor on also, you would think my shop manual would have said that. There is a couple other things in the manual that I thought didn't seem to tell you everything. Thank goodness for youtube, but the guy also left out rotating the motor again.
 

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I went and done this and sure enough the Honda CB450SC you have to rotate the motor on also, you would think my shop manual would have said that. There is a couple other things in the manual that I thought didn't seem to tell you everything. Thank goodness for youtube, but the guy also left out rotating the motor again.
On page 3-3 of the CB/CM 400 FSM it clearly says to rotate the crankshaft 1 full turn to the T mark after adjusting one side. Are you using something other than the Honda FSM?
 

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On page 3-3 of the CB/CM 400 FSM it clearly says to rotate the crankshaft 1 full turn to the T mark after adjusting one side. Are you using something other than the Honda FSM?
Your right so I totally missed it. I've got my mind elsewhere. Its on page 3-7 now I feel like an idiot and a half Owell not the first time. I did not read the final paragraph.


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Ok I got to ask is it normal to hear valve chatter? Or am I even hearing valve chatter. Not used to these twin motors. And where should I look for after market tci?

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"aftermarket TCI" ? not sure what you are looking for.
A light amount of tapping is a good thing for valves, means they're on the slightly loose side. More of a tick than tap.
 

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Ok I'm talking about replacement pulsar coil and and cdi/tci/ igniter the brains of the operation.

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