Problems....3 Cylinders, stalling *FIXED!*

[zaptoman]

So I went out for a ride the other day and everything was fine until the bike seemed like it had a sudden loss of power. It was going fine, power lost, then would surge back intermittently. When I turned the throttle to give it more gas, the revs didn't go back up. When I pulled up to a stop sign and pulled in the clutch, the bike died. I attempted to restart it and discovered that I didn't even have enough power to turn it over (which i now attribute to a faulty rectifier). I have now installed all new sparkplugs, and ran the bike to work. It worked great on all THREE cylinders. Just kidding, again, no power at all, and stalls easily, and I am at a loss as to what would be the matter, the plugs and wires are all secure, new plugs. What gives? Are these things related? Any ideas? I am new to bikes in general so any help is appreciated.

[gsxr400 racer]

got fuel got spark ,what are you charging at, plug wires on right ?????[/u]

[zaptoman]

Plug wires are as labeled, 1 to 4 left to right. Did a little experiment to see which cyclinder was loafing, pulled wires one at a time until it sounded the same on or off. Seems to be cyclinder number 2 but I don't really understand why it wouldn't be firing unless the carbs are gummed? I tried running some carb cleaner thru the fuel but doesn't seem to have made a difference. Are the carbs going to have to come out?

[gsxr400 racer]

okay take the air box off and spray some carb cleaner at that carb see if the idle picks up while it is running if it does you need to clean the carbs

[PitterB4]

Are you SURE that wire is connected securely, with good contact?  Are you getting spark when you pull it like that?  Orig plug wires?  You could very possibly be securely screwed into the plastic part of that lead without any of the actual wires making contact.  If it is orig wires, I'd take the cap off of the wire, cut a quarter inch off and reattach it.

[bonobandit4]

got fuel got spark ,what are you charging at, plug wires on right ?????

It looks like you may have narrowed it down to a single carb or cylinder, but I didn't see an answer to the question about 'what r u charging at'.  You said that you determined you had a faulty rectifier, but then you said that you replaced the plugs.  Did you replace the rectifier too?  

I know when I pulled the plugs to check for spark, I had one lead come off comletely just last month.  Pitter makes a good point.

[Krautwagen]

okay take the air box off and spray some carb cleaner at that carb see if the idle picks up while it is running if it does you need to clean the carbs

Exactly.  If #2 is missing, then yo need to figure out why.  As stated above, if you spray some carb cleaner into the #2 carb and the idle picks up, then you have spark, which means that fuel is the problem.

Another way to determine this is to pull the #2 plug.  If it's wet and smells like gas, then you don't have spark.  If it's dry, then you should have spark.

If it's fuel, then you'll have to pull the carbs and give them a cleaning.

Sounds like you've got something plugging a main jet.

[zaptoman]

Okay, the problem SEEMS to have been solved by pulling the carbs and giving them a cleaning (turns out it was cylinder 1) no, I have not had the opportunity to replace the rect yet. However in this process, it seems i have another problem, as now the bike doesn't come down quickly after being revved, it seems to take a while.

[Krautwagen]

That is a sign that the pilots are too lean.  Did you move the screws?  You'll want to find the nice medium between bogging when you blip the throttle at idle and taking a while to come down.

[zaptoman]

Screws? I can't even find those screws. The mixture ones right? Should be a flathead screw on the bottoms of the floats? Mine seem to be missing.

[PitterB4]

They may be covered with brass plugs which would obviously mean that you didn't mess with them.

It also may indicate a vacuum leak too, right?  Make sure everything was reattached securely.  Did you do anything with the synch screws (3 screws accessed from the top of the bank between the carbs)?  Being out of synch can also make the RPMs hang.

[zaptoman]

Looked at those other screws, but didn't touch. It would seem to be a vacuum leak, as from what I know the symptoms are consitent with that kind of thing. Will be checking all the hoses now I guess.

[zaptoman]

It's not a vaccuum leak as far as I can tell, checked all the hoses. I think it might be that the carbs are off balance.

[Red01]

Can still be vacuum related even if all the hoses look fine. Take some carb cleaner, starting fluid, or WD-40 and spray it around the vacuum hoses/plugs/connections. Also spray the manifold between the carb and block to be sure it's not leaking there.

Also check the condition of the vacuum diaphragm on the top of the carb. If it's pinched or cracked, you'll get a vacuum leak there.

Could be carb balance, but it would have to be WAY off to give you a dead cylinder.

[zaptoman]

She's fixed! Here's how. When we pulled the carbs it seems that we did a couple things wrong. Firstly, on the first and fourth carb, we lost the little O-rings that seal around the vacuum tester thingy. Second, when we put the carbs back together we used some silicone gasket sealer to seal the diaphragm to the carb. When we started the engine, this stuff had not cured fully and seeped downwards, causing the piston valves on the first and last carbs to stick. These problems in turn did not allow us to balance the carbs correctly (vacuum leaks, sticking air intakes). When we realized our folly we replaced the o-rings, put the carbs back together correctly, and then balanced the carbs. (Its amazing how much better this works when you don't have major vacuum leaks!) In short, now the bike runs like a dream. Thanks for all the help!