Topic: 3 and 4 Fuel Issues

[danielcgordon]

Carbs are cleaned and synced properly.

New Plugs

I'm getting fuel into the carbs-simply by touch 1 and 2 get hot, 3 is warm and 4 is hotter then room temp but I can have my hand to it without even getting uncomfortable.

Any Ideas?

73 750K

[birdy]

Hey! This is exactly what I've recently posted about...seems like a common problem then- is there a common solution? My carbs were bench synched by PO, no overfow etc...

[danielcgordon]

Ok so I read the other post...I didn't see it at first and I'm sorry.
I don't have the stock tank on there. Stock has the petcock with the 2 lines out, I do have the single line out. In turn I had to add fuel line with a Y connector. It does get fuel to 3/4. I can pull the bowls off or loosen the screw and there is gas. Is the fact that I have gas enough? Would that make any difference with the flow of things?

Also what are the repercussion to riding like this? I haven't been as I don't want to cause any major problems.

[birdy]

So- no kink in my fuel pipe.
Took apart every electrical connector I could easily see and reconnected- voila - all 4 firing OK now. I have no idea which one was at fault, but suspect it could be the wire coming out of the points cover on right side of engine cover that goes into a connector?
Hope this helps you...

[danielcgordon]

I did find a short leading to my ignition. I'm not sure if that is the issue or not but it is there. Now I run into the time issue. On top of that I don't know anything about electronics and get frustrated easily...

We'll see how all that goes.

Anybody of the repercussions of riding without 3 and 4 firing properly...like I said I haven't been

[mystic_1]

I don't know anything about electronics

Congratulations, your bike has few if any components that could be considered "electronics"   The rectifier sorta counts as it's made of diodes, but those diodes are huge ancient affairs that most electronics guys would consider akin to stone knives

I wouldn't put many miles on the bike when it's running only on two cylinders, although it won't kill anything right away to do so.

Have you tried swapping your spark plugs around to see if the problem follows the plugs?  I'd do that, and verify the float levels.

Your "Y" adapter in the fuel line should be fine so long as there's no restrictions or air bubbles.  I've run my bike set up like that for years.

mystic_1

[birdy]

On my earlier reply regarding the possible electric wire bad connection which solved my 3-4 firing problem; does anyone know what circuit would only affect 3 and 3 cylinders, not the other 2?

[tlbranth]

Mystic - I have to disagree with your statement that it shouldn't cause any harm to ride with only 1 & 2 firing - especially if the problem is with the ignition. In that case, unburned fuel will wash oil from the rings and most likely cause some damage.

[mystic_1]

I didn't say it shouldn't cause harm, I said it wouldn't kill anything right away.  By "wouldn't put many miles on the bike" what I really mean is "I wound't drive it around more than is necessary to diagnose and debug the problem" which can sometimes involve zipping around the block or up and down the street a few times.

By all means, don't drive it to Sturgis like that

BTW running it on two cylinders will do more than score your cylinders and bork your rings, think of all that unburned gas building up in the muffler! 

mystic_1

[RedDawn]

On my earlier reply regarding the possible electric wire bad connection which solved my 3-4 firing problem; does anyone know what circuit would only affect 3 and 3 cylinders, not the other 2?

Spark plug wires

Points fire 1-4 and 2-3, so if they were messed up your inside (2-3) or outside (1-4) cylinders would be having trouble. Coils are the same. Any wire that feeds either will affect the inner or outer pairs of cylinders. You might have had stuck floats that came free(er) when you checked the bowls. I'd definitely check your float levels. Also, when you were having the problem did you have it on the side stand, and when the problem went away was it on the center stand? The fuel may just have not arrived in sufficient levels on the higher cylinders until they had an equal chance as the lower ones.

[birdy]

It was on the side stand, but has since been running fine on all 4- when on the side stand..the mystery continues..