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Troubleshooting to see if it is on one cylinder?

Posted: Fri Jul 30, 2010 1:39 pm
by jnagle2
So I'm familiar with the airheads, but this new bike has me confused. single exhaust, fuel injection. new stuff.

I had to remove the tank to diagnose a fuel leak. Now that I have the tank back on, it will only run rough and die at idle. Along with that, I hear a strong knocking noise when it is at low rpms, but its centrally located.

Question:
What is a good process for troubleshooting faulty issues at the cylinder? Since this is a single exhaust, I can't determine which cylinder isn't firing by feeling the exhaust. Is there a quick way to check which side is at fault?

Oh, and i can see both throttles cables pull when I turn the throttle. I've seen that recommendation of it unsetting, that doesn't seem to be the issue here.

2003 with less than 3k miles (yes, less than 3k, bought it one month ago).


I'm assuming my reseating of the tank caused the issue, but i'd like to zero in before i pull it again.

Thanks!
Jonathon

Re: Troubleshooting to see if it is on one cylinder?

Posted: Fri Jul 30, 2010 2:23 pm
by riceburner
can you feel which exhaust header is hotter??

RE the unseating issues - just double check the throttle cables are indeed seated correctly.

Re: Troubleshooting to see if it is on one cylinder?

Posted: Fri Jul 30, 2010 2:30 pm
by boxermania
Since you removed the tank there are two possibilities that come to mind:

1) Are the fuel quick connects all the way home? Sometimes they don't close completely, limiting the amount of fuel that can get through. It helps tremendously to lubricate the o-ring's as they tend to expand in the presence of air and make the couling up difficult.

2) Did you check to see if the throttle cable to the TB is fully seated inside the adjuster? Since there is a lot of work on the right side of the bike to remove the tank it isn't uncommon to get the cable sheath out of the adjuster and then it hangs up on the top of the adjuster.

Good luck and keep us posted

Re: Troubleshooting to see if it is on one cylinder?

Posted: Sat Jul 31, 2010 11:06 am
by Colin
I suppose you could perform a cylinder drop test of sorts by removing the injector leads one at a time and observing any changes in behavior. Any change will be dramatic and very noticeable.

Re: Troubleshooting to see if it is on one cylinder?

Posted: Sat Jul 31, 2010 1:42 pm
by WorkinMan
I'm still trying to figure out why you can't just feel the exhaust headers where they leave the heads? My exhaust is a DUAL exhaust until it meets up with the Kitty Cat. I would think yours is also.

Re: Troubleshooting to see if it is on one cylinder?

Posted: Sat Jul 31, 2010 4:56 pm
by boxermania
Exhaust temperature measurement can be done as WorkinMan sugested, procure an IR temperature gun (borrow or buy at Harbor Freight for ~ $25) aim at the exhaust pipe as it comes out of the cylinder head.

Re: Troubleshooting to see if it is on one cylinder?

Posted: Sun Aug 01, 2010 4:32 am
by jnagle2
you are right about the exhaust headers. however, my bike was still hot from when it was running normally, so i didn't think to gauge the heat.

it was the throttle cable. i checked to see that both throttle cables were responding, but i didn't check that seating part.

Thanks for all your help!
Jonathon