Motor seized when starting cold - please help

[AlanDog]

Welcoming wild guesses and opinions. I have a track day scheduled for the 15-16th at Reno/Fernley. I just rebuilt the carbs and a few days ago fired it up for the first time. It did start and run but wouldn't idle without holding the throttle or having the choke on--it may have been just a fuel starvation issue since they were dry and I only had a little gas in the tank. Then, all of the sudden the engine siezed up. When I try to start it now, I hear the solenoid engage, but nothing moves. I charged the battery for two days and same thing. The battery was on a trickle charger when I was rebuilding the carbs and reads > 12V. I put the bike up on the center stand and tried moving the rear wheel with the gears engaged--it doesn't budge regardless of gear.

So the engine was cold, I mean I had only turned it over for a couple of minutes max, wasn't reving it hard...  oil and water levels okay. Before I rebuilt the carbs it was running. I did not take off the valve cover, but it does have a relatively new manual cam adjuster. Can the valves be so out of whack to sieze the engine?

Any other ideas or things I can try to troubleshoot this? Help! 

[pmackie]

Hey AlanDog

The first thing is to determine if it is really seized. You should be able to remove the left side cover (or the screw-in case access if the B4 has one?) and turn the crankshaft with a socket. Go slow, and check for movement in both directions. If you feel significant resistance, or it is stuck, you will have to start looking in more detail. Remove the plugs and see if you can see anything. Next take off the valve covers and look for anything amiss there.

Doesn't sound good however...

[AlanDog]

Paul, thanks for the reply. Well, I was able to turn the crankcase bolt, so it wasn't seized, apparently turning it from the back wheel in gear isn't that easy... as it still wouldn't turn from the wheel (I read on the internet it would work!) And the good news is it magically started up and idles fine now.

The bad news: I have no idea why! Intermittent starter or solenoid... I guess time will tell! 

Well it may be a bit premature to call my carb rebuild a success given I haven't ridden out of my garage yet, but the bike was idling nicely, so I think I at least put them together correctly!

[interfuse]

Seeing you just messed with the carb I'm guessing it's hydrolocked. Remove sparkplugs and turn the motor over and see if gas comes pouring out. If so you need to fix the leaking carb and do an oil change.

[AlanDog]

Well the oil level looked fine after the problem disappeared. So I took it out and rode it to work. 

Now it idles cold okay, but won't idle hot. I apparently had the idle adjustment screw unscrewed so my adjustments were doing nothing. Fixed that today, put it together, now it won't fire up. And I get the strange feeling it is *not* related to the carbs: it was firing up and running before, just not idling well.

It has previously died mysteriously on the side of the road and waiting around and wiggling wires fixed it... I thing I am now having that problem.

So how does the ignition wire connect to the coils? I'm just confused how to replace the wires. I know the spark plug side just pushes in (I spliced mine back to get fresh connections). Coil side is the same?

[interfuse]

The spark plug wires screw onto the coil.

Also the 12v wires going the coil are prone to breaking. They are thin and exposed to wind.

[AlanDog]

Well the motor not turning over problem happened again, this time I noticed fuel dripping from one of the carbs and Mike you were right, when I took out the spark plug it was filled with fuel. I used a syringe and a rubber line to siphon it out.

Well, at least now I know which carb is having issues. I also was running it for 15 seconds and trying to figure out where the problem by checking the exhaust manifold temp, and yeah, that cylinder #2 manifold was not getting as hot as the others...

Thanks for the help.

[AlanDog]

Okay, I have all new o-rings, they fit tightly, I did an air seal test with a homemade mouthpiece and verified that the float valves are sealing with air and water when the float is up, and I've bent my float tabs to their max so the floats are shutting off asap, but when I put a fuel line on the carb fuel inlet and add fuel, I get gas coming out the main air jet at the bottom of the throttle bodies. 

So what next? Should I try new o-rings again? I was thinking I could try gasket-maker on the larger o-ring. Or is it the float valves (all new)?

[AlanDog]

I'm out of ideas. The only conclusion I can draw is that some of the new components in the rebuild kit (o-rings or float valve) are not sealing up with my carb bodies. Other possibilities?

But can someone confirm that this fuel test is valid--with the carbs flat on the ground and a fuel line 2' above them, should the floats be able to stop fuel from entering the float valve? Or am I putting too much fuel in/too high of elevation?

[interfuse]

Carbs flat on the ground? They need to be vertical to work. Ideally on the bike. I know if you leave the bike on prime over night gas will push past the floats.

[AlanDog]

Oh, by 'flat on the ground' I mean the bottom (float bowl) is sitting on the ground.... well I will get a shorter clear tube that will fit directly on the carb inlet and see if they will hold gas with that. I guess I will have to change my oil now, so testing this out on the bike is not an issue. If it keeps leaking I'll try detach the carbs and do the test individually. Thanks.

[interfuse]

What do you mean by detach the carbs? Don't break down the bank of carbs. Leave as a set of 4. Once you separate the carbs you get into a whole different type of leaking.

[Chris H]

Well the motor not turning over problem happened again, this time I noticed fuel dripping from one of the carbs and Mike you were right, when I took out the spark plug it was filled with fuel. I used a syringe and a rubber line to siphon it out.

Well, at least now I know which carb is having issues. I also was running it for 15 seconds and trying to figure out where the problem by checking the exhaust manifold temp, and yeah, that cylinder #2 manifold was not getting as hot as the others...

Thanks for the help.

I would swap the float etc from this carb to another to prove it is the float valve not sealing.
You may have another less obvious problem like a cracked carb body.
If the problem doesn't swap the first thing i would look at is the o'ring thats under the white plastic throttle slide holder.

[AlanDog]

Chris, I think you've found what I missed--that slide holder o-ring. My rebuild kits didn't have an o-ring for that, and I don't even remember seeing it when I had them apart.

[AlanDog]

  Put in new o-rings on the emulsion tube/plastic slide holder... still leaking fuel out of the pilot air intake--should I just assume the carb with the fuel leaking out of it is the bad one? Because couldn't a leak in one just cause the gas to go downhill and spill out of the other ones?

 I am looking at the factory service manual trying to figure out what is in the pathway of the pilot passage. It could be the float valve leaking as that would flood the entire bottom of the carb. What else? Does the jet needle need to seal and hold back fuel when it is completely closed? Could that not be sealing right?

I had a great time last weekend at my first trackday. Rode my 1981 Honda cx500, surrounded by mostly 600cc supersports. It was an overwhelming experience at first, but was having fun by lunch. http://www.youtube.com/watch?v=Qh5pdE7Vd8c&feature=plcp
I was scraping pegs quite a bit, really need the bandit running before I go out there again.