cylinder 4 missing

[niko]

Ive searched the forum, and while Im sure an answer is out there somewhere I cant find it. When my bike is running on idle it sounds rough, and if I pull the plug wire off of #4 there is no change in the idle. If I pull any of the others it will immediately die. I checked valves as per bikecliff's website, found them all in spec although there does seem to be a little bit of noise coming from somewhere in there (sounds kind of like tappets but I'm really not sure if its abnormal or if I'm just looking for something.) I have spark, and I think everything is ok with the carbs although I just pulled them off to go through them again looking for a clogged circuit. The funny thing is that the pipe is getting hot like it is firing some of the time. I did find a little bit of junk in one of the float bowls, carbs will be dipped again, can an intake valve get clogged, and how could i double check the valves are functioning properly?

 

[BassCliff]

Hi,

Have you tried new plug caps?



Thank you for your indulgence,

BassCliff

 

[niko]

I did actually try new plug caps, and new plugs. It didn't seem to make an appreciable difference. as i think about it there is a little more to the story though. when I first noticed the problem it was that when I pulled the spark plug cap from cylinder three it would not drop in idle, it later moved to four, and three is firing again, but four is gone. This bike uses a two dual throat carb setup, so I thought that maybe there was something wrong with the carb because one body feeds both cylinders, and there was a little black gooey looking junk in the float bowl (no idea where it came from i have an inline fuel filter. I am dipping it tonight, and will reassemble probably tomorrow. Is it possible for intake valves to get gummed up like a carb, i dont really think its just the carbs, and I don't think the cylinder is getting gas. Maybe im over thinking it and its just the idle circuit plugged, i guess ill find out tomorrow.

 

[kudagra]

#1 and #4 both fire at the same time (but only 4 piston should be in the compression stroke).

Hook up a spare spark plug to each of those leads, ground the spark plugs and make sure you are getting spark in both. You can lose just one side of a coil. If thats all good..check the compression. If thats good Id say it was carbs.