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Discussion Starter · #1 ·
I have rebuilt this 73 CB450 after a previous owner let it sit and one piston became rusted in place. Following the guidance of the clymer manual, adjusted the valves to spec, rebuilt the carbs, torqued everything down to spec, and tried to get it to start.

The electric starter still works and spins the motor. I can feel pressure being sucked in thru the carbs and blown out from the exhaust. My plugs and coils are new and do provide spark. I tried using my old points but couldn't get the motor to start up with those old points. Last week I ordered and installed the common motor collective shockwave kit and installed that per their instructions and appears to be working as designed except - - - motor won't start.

Now comes the self doubt. Did I actually set the valve clearance properly? Did I set the clearance on the points and on the new common motor shockwave properly?

I put gas in it (admittedly it was old gas) and I'm getting some intermittent blue flamed popping from out of the air intake side of the carbs.

My hypothesis and all I can think of is that my intake valve clearance isn't timed properly to let fuel into the cylinder. Has anyone experienced this who can help guide me towards a successful running motor?
 

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Do you know for a fact the camshaft is correctly timed? Choke closing all the way? Cranking it with full choke and little to no throttle?
 

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Spark happening in the correct cylinder at the correct time ?

Go back a few steps, check valve / cam timing and valve working clearance, check ignition timing...

Use fresh fuel...have a fire extinguisher handy !
 

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From your description of the symptoms it does sound like you timing is 180* off. I'd double check that first. Next, you can check your compression and that will tell you if your valves are set good enough to run. Even with low compression an engine will run or at least try to run, but it does need some, 50 psi would be enough to get you started. Also, a burst of starting fluid will confirm if your carbs are supplying fuel properly.
 

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Discussion Starter · #5 ·
I went back and double checked the valve clearances and they were all good. I’m thinking this is all related to timing. Can you tell me from the following images how jacked up is my spark advancer? The first image is the tic mark of the spark advancer at LF and the second image is at F:
315302
7202188B-0EF0-49C5-8495-903EFF6437EF.jpeg
315303
7202188B-0EF0-49C5-8495-903EFF6437EF.jpeg

The above is at LF
4516378E-C0CF-49F8-9DBB-E8FD460C65C8.jpeg

The above is at F
 

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You need to remove the 10mm bolt that holds the advance mechanism then you will find a mark on the central pillar that must line up with the punch mark on the cam. If it is 180 degrees out then so is your timing.
 
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I went back and double checked the valve clearances and they were all good. I’m thinking this is all related to timing. Can you tell me from the following images how jacked up is my spark advancer? The first image is the tic mark of the spark advancer at LF and the second image is at F: View attachment 315302 View attachment 315302 View attachment 315303 View attachment 315302
The above is at LF View attachment 315303
The above is at F
I went back and double checked the valve clearances and they were all good. I’m thinking this is all related to timing. Can you tell me from the following images how jacked up is my spark advancer? The first image is the tic mark of the spark advancer at LF and the second image is at F: View attachment 315302 View attachment 315302 View attachment 315303 View attachment 315302
The above is at LF View attachment 315303
The above is at F
Hello, I cant say your spark advancer is OK or not, but I can say that your valve adjust shaft is incorrectly installed. 14mm nut should have flat washer, and the hashmark should point away from spark plug not towards it, in all 4 locations. Hashmark for this left exhaust valve should point to near 8 o'clock position, rotate this adjust shaft counter clockwise. All ignition and valve timing installation set points are at Left Top Dead Center. Valve adjust is at Left top and Right top as needed. So to answer your question "Did I set valves correctly?" The answer is "No". I would check camshaft timing also, then inspect ignition timing. Good Luck, John
 

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The auto advance unit itself can be disassembled, cleaned and put back together 180° degrees out.
Ask me how I know?
 

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Honda John is correct in that your valves are incorrectly adjusted and the advance cam is 180 out......
Text me your Hondatwins name and phone number, and then phone me......
 

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I have rebuilt this 73 CB450 after a previous owner let it sit and one piston became rusted in place. Following the guidance of the clymer manual, adjusted the valves to spec, rebuilt the carbs, torqued everything down to spec, and tried to get it to start.

The electric starter still works and spins the motor. I can feel pressure being sucked in thru the carbs and blown out from the exhaust. My plugs and coils are new and do provide spark. I tried using my old points but couldn't get the motor to start up with those old points. Last week I ordered and installed the common motor collective shockwave kit and installed that per their instructions and appears to be working as designed except - - - motor won't start.

Now comes the self doubt. Did I actually set the valve clearance properly? Did I set the clearance on the points and on the new common motor shockwave properly?

I put gas in it (admittedly it was old gas) and I'm getting some intermittent blue flamed popping from out of the air intake side of the carbs.

My hypothesis and all I can think of is that my intake valve clearance isn't timed properly to let fuel into the cylinder. Has anyone experienced this who can help guide me towards a successful running motor?
-- The Clymer manual I have has one of the timing sequences wrong. I can't remember if it is the valves or the ignition. Anyway, go by the Honda 450 owners manual, not Clymer.
 

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--- I thought that I posted this already. -- The Clymer manual I have has one of the timing sequences wrong. I can't remember if it is the valves or the ignition. Anyway, go by the Honda owners manual, not Clymer.
 

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Discussion Starter · #12 ·
Hey folks so an update - I took the valve covers off and the stator cover off and properly aligned the timing marks. The first time I missed the key factor of aligning the stator with the cam tic marks.

id like to think I have the engine timed properly now.
Except here’s my new problem. I can get the engine to fire up albeit with starter fluid. My left cylinder seems to get flooded and my right cylinder seems to be starved. Im also getting exhaust coming out of my left carb.

the carbs have been gone thru and operate properly. They, I am confident, are synced using the guitar string method.

my new question is how to I get this to reliably start up with equal fuel into each cylinder and exhaust going in the right direction? Do I need to reevaluate my inlet valve clearances?
 

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Hey folks so an update - I took the valve covers off and the stator cover off and properly aligned the timing marks. The first time I missed the key factor of aligning the stator with the cam tic marks.

id like to think I have the engine timed properly now.
Except here’s my new problem. I can get the engine to fire up albeit with starter fluid. My left cylinder seems to get flooded and my right cylinder seems to be starved. Im also getting exhaust coming out of my left carb.

the carbs have been gone thru and operate properly. They, I am confident, are synced using the guitar string method.

my new question is how to I get this to reliably start up with equal fuel into each cylinder and exhaust going in the right direction? Do I need to reevaluate my inlet valve clearances?
If your cam timing was incorrect, it's highly possible you have bent valves. I'd check compression before doing anything else.
 
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