1981 xj550 Maxim. One cold exhaust header...

Hey everyone! Last week I picked up a 1981 xj550 maxim. I thought it was running fine until I touched the second header pipe and it was cold. Seems to be idling and running fine without that second cylinder too.

I was "told" when I bought it that the carbs were just rebuilt so that leads me to believe it isn't a clogged jet. I haven't checked the spark plugs yet so it could be that. But I was just looking for some insight as to what could be the problem if its not the carbs or the plugs.

Thanks!
Nicholas Rondilone

 

the 550 runs great on 3 cylinders.
unscrew the sparkplug cap trim about 3/8 inch of wire off of the wire.
ohm out the spark plug cap should be 10K ohms. if it is an oem cap there is a screw cap inside the plug end that goes on the spark plug make sure it is snug
use some dielectric grease on the screw in cap and a little on wire then screw in back together.
see if that helps
it could also be a bad spark plug switch plug with another cylinder see if the problem moves with the spark plug.
if this does not work for you the problem may be in the carbs or you need to adjust the valves.
first thing you should do with a recent purchase is
check the valve clearances. once a year.

carbs need to be cleaned.
fuel levels need to be checked if cylinder 2 is low it may be starving for fuel
adjust mixture screws your bad cylinder mixture screw may not be adjusted properly 2-1/2 turns out from a soft bottom is where you start
what does your spark plugs look like? color tune works well for doing this.

carb sync may be your problem need to sync carbs

Cleaning your Mikuni carbs


Setting the fuel levels


Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

 

never trust what a previous owner says
some reading for you

The Information Overload Hour

The Ultimate Relay, Switch, Sensor, and Diodes Guide

IN THE CHURCH OF CLEAN

THE SECRET LIFE OF CARBURETORS

Something New, Something Naked

TALKIN' TECH: Various thoughts on various issues


Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II


Choosing Oil for a Wet Clutch Motorcycle


SAFETY ALERT Drum rear brake bike owners please take a look


our forum supporting vendor plenty of parts and advice Chacal

XJ4Ever - Supporting Vendor

 

Don't believe anything the PO told you.

 

It really does! I love this thing! Thanks for the suggestions, i'll get on all that tomorrow and let you know how it goes!

 

Guess I won't eliminate the carbs as a possible factor then! Thanks for the links. Looks like I've got some reading material for the evening!

 

That seems to be the general consensus. Good to know!

 

I ordered new carb boots, valve cover gasket, andfloat bowl gaskets. They should arrive within the week. Once they get here, a friend of mine that's got all the right tools, shims, and knowhow is going to help me through all of it. Though with all the knowledge I've attained through the helpful folks here, I feel like I already have a good idea what to expect. Hopefully this time next week my baby will be flying on all 4 cylinders.

Its still crazy to me that I would have had no idea there was anything wrong had I not accidentally NOT burned myself. She rides like a dream on 3 so I'm really excited to feel full power.