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Discussion Starter #1
Hi all, new to this forum.
Short story: '71 cb450 motor and only the necessities to start, kick started fine the first time, and it idled fine. Next, tried the starter motor, didn't work, gas shot from air jet. Kick start is now verrryyy difficult to turn, and it doesn't spring back up anymore. Pistons move up and down with no problem.
Help?

Long story:
I recently picked up a cb450 motor (just motor and carbs), and then some. I plan on using it for a country yard go kart - so budget is low. I was told it had been sitting around for a little under 10 years. Anyhow, I went the cheap route and got universal coils and condensers to get the engine to start. I greased up the cam lobes and put in fresh oil, cleaned the carbs and such. Hooked up the coils and condenser, etc... I mocked up a wood frame to hold the engine while i tried to kick start it.
A few kicks later it started and idled perfectly fine, but without headers, i turned it off after a minute.
After i was sure it could idle, I wanted to make sure i could start it with the starter motor since I didn't want to deal with kick starting it on a go kart chassis.
I hooked up power to the starter motor, nothing happened just slight whirring. It was a very old battery that I let charge earlier that morning. I figured the battery wasn't fully charged or giving out enough current. I tried to jump start the motor with my car; this time, the starter turned the engine over a couple times and the carbs SHOT gas out of the air jet. I let the starter cool for a few minutes, tried again, and same result. The starter motor is hooked up properly, and the starter clutch rotates freely one way, and restricted the opposite way.
So i go to kick start it, and the kickstart will not move as easily as before, nor will it spring back into place. Also, one of the carbs is spewing gas out of the overflow, so I'll have to check the needle and such.

I've tried to turn the crankshaft via the flywheel bolt, and it turns fine clockwise(? don't remember). The crankshaft will only turn a 180 degrees before it will get really difficult when i turn it counter-clockwise.

Whew! that's a lot to read. any help? Thanks.
 

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quote:Originally posted by ddlaz

a burned valve stop a kickstarter from retracting? I dont see how thats possible.
if the burned valve (or cracked valve) is stuck open inside the cylinder then it would be very hard to kick because the piston would be pushing against it.

it was pretty stupid to run an engine without an exhaust pipe of some sort.
 

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Since you don't have any headers on the motor - it should be easy enough to take a peek to see if the valve is stuck open.

Just for something to try, pull the spark plug on both cylinders and see if you get any gas (or liquid) out of the motor. I just had a harley that was shotting gas through the valve cover gasket like a fire hose due to a carburetor that was over flowing with gas and filling up the cylinders. I had never seen anything like this before....
 

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quote:Originally posted by bmartin

Since you don't have any headers on the motor - it should be easy enough to take a peek to see if the valve is stuck open.

Just for something to try, pull the spark plug on both cylinders and see if you get any gas (or liquid) out of the motor. I just had a harley that was shotting gas through the valve cover gasket like a fire hose due to a carburetor that was over flowing with gas and filling up the cylinders. I had never seen anything like this before....
It's called hydraulic-ing or hydro-locking a motor, depending on where you are from. On hondas the carbs usually just overflow out the float bowl drains before they begin filling up the cylinders but it does happen from time to time id the bowls are gummed up.
 

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Geeto -

I've heard of hydro-locking before, I've never seen a motor shot gas like a fire hose out the value covers before....
 

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Discussion Starter #8
Thanks guys, but i've been there, done that with pulling the spark plugs out and cranking. No gas shot out. Easier to crank via flyhweel with the spark plugs out, of course. If the valve were stuck open, the cranking wouldnt be fighting compression in whichever cylinder, so no open valves hitting the pistons.

I wouldn't say that it's more difficult to kick, I never really thought about the force required. The problem is that it doesn't retract as usual since I tried starting it with the starter motor.
 

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I have a 73 cb 450 and the starter locked up on it, it turned out to have a bearing locking up, I think out of the one way clutch, cant remember about 2 years ago.
 

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Discussion Starter #10
the starter motor bearing? Nah, my starter clutch works fine. The starter turns the engine over, just not fast enough to start the engine. I can start it fine with the kick start.
 
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