Need Advice: first start after long neglect

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jd48792

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I purchased a well-abused 89 over the winter that had been sitting for four years. Replaced the battery, then the starter, then the clutch slave cylinder. Rebuilt the carbs as per NaughtyG's instructions (except that I replaced all components that came in the rebuilt kit, except the float needle seat; and I didn't touch the slide needle), cleaned the fuel tank, and installed new spark plugs.

I finally got to the point where I could start the bike today. It started right up, idled, and revved fine with the choke on. But I had to play with the choke to keep it running as it warmed up. Eventually, it got to where it was obviously running too rich with the choke on, but whenever I tried to turn it off, the bike was clearly running too lean: backfiring and missing on at least one cylinder, and dying unless I kept the rpms up above 3K.

Before I start to randomly check things, I'm wondering if there are some obvious issues that are consistent with these symptoms.

Thanks in advance for your advice.
 
Check the coils and spark plugs for fire and maybe a good carb syncronizing.
Welcome to the forum.
 
Check the coils and spark plugs for fire and maybe a good carb syncronizing.
Welcome to the forum.

Why would a bad coil only cause rough running with the choke off?

I did a bench sync, but it's hard to do more when I can't keep it running. And again, why would sync only be an issue with the choke off?
 
Why would a bad coil only cause rough running with the choke off?

I did a bench sync, but it's hard to do more when I can't keep it running. And again, why would sync only be an issue with the choke off?

A bad coil or coil wire connection would be one reason as they become corroded from sitting to long. Did you clean the two jets in the jetblock? Another possible reason.
It's not a choke although that is what the lever says- it is an enrichiner ad will run when partially open. Read through the thread I sent to see what others have said.
There are reasons one cylinder is backfiring-wrong amount of a/f,sync or fire from the wire or coil.
 
A bad coil or coil wire connection would be one reason as they become corroded from sitting to long. Did you clean the two jets in the jetblock? Another possible reason.
It's not a choke although that is what the lever says- it is an enrichiner ad will run when partially open. Read through the thread I sent to see what others have said.
There are reasons one cylinder is backfiring-wrong amount of a/f,sync or fire from the wire or coil.

I cleaned everything in the carbs and replaced the mains with 147.5 (the bike has cobra slash cut pipes - unfortunately)

Do you still offer the COP setup? The coils and wires do look pretty sad (as does just about everything else) so the COP option might make more sense in the long run.
 
I cleaned everything in the carbs and replaced the mains with 147.5 (the bike has cobra slash cut pipes - unfortunately)

Do you still offer the COP setup? The coils and wires do look pretty sad (as does just about everything else) so the COP option might make more sense in the long run.

That's classic pilot circuit clog. Further carb cleaning might be indicated.
 
Sounds like you picked up a bit of trash into the carbs and its time for a shotgun.

http://vmax.lvlhead.com/tips/shotgun.htm

The fuel filter is paper so its actually pretty easy for a bit of rust to slip thru. As far as the shotgun goes, Ive had better luck taking PAJ#2 out, so a full blast of air can go thru the idle circuits.
 
Sounds like you picked up a bit of trash into the carbs and its time for a shotgun.

http://vmax.lvlhead.com/tips/shotgun.htm

The fuel filter is paper so its actually pretty easy for a bit of rust to slip thru. As far as the shotgun goes, Ive had better luck taking PAJ#2 out, so a full blast of air can go thru the idle circuits.

I removed all PAJ#2 jets, soaked, sprayed, and blew out the passages. But I guess it wouldn't hurt to hit it again.

I also replaced the fuel line between the pump and carbs and installed an additional sintered bronze filter in the line as a precaution. So I doubt anything new got through.
 
I'm really getting frustrated. As per everyone's advice, I checked the spark - looks good. Took the air box back off and ran through the shotgun again, several times. Lots of carb cleaner and 100 psi air pressure. It seems to be blowing out of all the right orifices; at least the same ones on all four carbs.

The bike starts fine, idles and revs smooth with the choke/enricher on. But eventually it starts to warm up and begins running too rich for the choke. But as soon as I start to close it off, the bike dies unless i immediately push the choke lever back on, regardless of how much throttle I give it. Soon, it wont keep running with or without the choke. But as soon as it cools back down, it starts right up again.

As I understand it, a clogged idle air circuit would cause the bike to run rich. But mine seems to be running too lean without the choke on.

Could I have assembled something wrong when I rebuilt the carbs?

The guy who owned it before me was an expert in total neglect, and it wasn't running when I got it. So I can't be sure there isn't something else going on.
 
I'll be back in town in a week, and can come go through your carbs with you if you want. Lord knows I've been through mine enough times
 
I'll be back in town in a week, and can come go through your carbs with you if you want. Lord knows I've been through mine enough times

I appreciate the offer, Dave. I hate to drag you all the way down here (the bike's in Colonial Beach). But if you'll be in the area, I could certainly benefit from your experience. Just pm me if you find a time that works for you. In the meantime, I'll keep working on it.
 
I'm finishing a 10,000 mile trip. A couple hours will be fine. Plus, it's still summer for me for one more week. We'll get it figured out. I'll bring my cut screw drivers and Morgan carbtune with me (probably would come down on my tenere).
 
I'm finishing a 10,000 mile trip. A couple hours will be fine. Plus, it's still summer for me for one more week. We'll get it figured out. I'll bring my cut screw drivers and Morgan carbtune with me (probably would come down on my tenere).

Sounds good. Just pm me. I can arrange to meet just about any time with a day or two notice.
 
I'm really getting frustrated. As per everyone's advice, I checked the spark - looks good. Took the air box back off and ran through the shotgun again, several times. Lots of carb cleaner and 100 psi air pressure. It seems to be blowing out of all the right orifices; at least the same ones on all four carbs.

The bike starts fine, idles and revs smooth with the choke/enricher on. But eventually it starts to warm up and begins running too rich for the choke. But as soon as I start to close it off, the bike dies unless i immediately push the choke lever back on, regardless of how much throttle I give it. Soon, it wont keep running with or without the choke. But as soon as it cools back down, it starts right up again.

As I understand it, a clogged idle air circuit would cause the bike to run rich. But mine seems to be running too lean without the choke on.

Could I have assembled something wrong when I rebuilt the carbs?

The guy who owned it before me was an expert in total neglect, and it wasn't running when I got it. So I can't be sure there isn't something else going on.
How do your intake manifolds look? When I first got my first one it had radiator hose instead of intakes. My second one had cracked intakes and would only run with the choke a little open.
 
How do your intake manifolds look? When I first got my first one it had radiator hose instead of intakes. My second one had cracked intakes and would only run with the choke a little open.

I'll check them tomorrow. I know they're stock, but I haven't looked real close. Sounds promising. I guess I should also check the caps on the balancing fittings.
 
I'll check them tomorrow. I know they're stock, but I haven't looked real close. Sounds promising. I guess I should also check the caps on the balancing fittings.
A couple of ways to check for cracks is spray a shot of wd-40 on the intakes while it is idling and listen for a rise in rpm's or an unlit propane torch will do the same.
 
Dave is a great guy, and had to bring a Vmax basically back from the dead. I'm certain that he can help.
 
Probably a silly question but have you checked that the hose between the inlet manifold and advance unit is in good condition and properly attached?
 
But as soon as I start to close it off, the bike dies unless i immediately push the choke lever back on, regardless of how much throttle I give it. Soon, it wont keep running with or without the choke. But as soon as it cools back down, it starts right up again.

Don't know if anyone mentioned this, but could this symptom look like a pick up coil is starting to go bad? I know when i had that problem, the bike would turn on when cold,, start to warm up and pop and spit,, then become erratic, then totally die, and would not start back up till it cooled down.

Just something to think about.
 

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