Author Topic: IDEAS PLEASE: #2 Cylinder misfires at low rpms on 98 1200s (Read 6196 times)

socalbandit · « **on:** February 21, 2006, 10:22:38 PM »

At less than 4000 rpm #2 cylinder is misfiring on my 98 1200s When I did a carb sync the other day is how I was able to determine which cylinder it is. It happens more when its cold and less when hot, but still does it when its hot. Especially on deceloration when I get back on the gas I can here it pop. I am looking for ideas for what it might be.
Some history on the bike:
Just bought it. It had been sitting for 2 years in some guys garage. He was the original owner and logged 33k on it. Right when I bought it I had my friend do a valve adjustment for me. I then put in new plugs. It still idled like crap and would sputter/have no power down low. So I took all the carbs off took them apart and sprayed them out with carb cleaner. Put them back in and tried to do a carb sync. This is where I noticed #2 misfiring. It is a little better down low, but I still have to rev it to get it going. When I nail it there is a slight hesitation then it takes off and feels ok. The problem for me is I never new what the bike feels like when its running perfect. I just ordered an Ivans jet kit for it and will install that when I get it. I was wondering if anyone else has had this problem or might know what it is. Thanks in advance, Jon.

Red01 · « **Reply #1 on:** February 22, 2006, 10:10:52 AM »

You need to figure out if it's a spark or carb problem. Do you have access to an induction type timing light? If so, you can clip the plug lead on the suspect cylinder lead and see if it's sparking regularly. If it's not, then you have a bad lead. If it looks normal, then you've got a carb problem and that carb needs a better cleaning than just a quick spray with cleaner... like a bath in a carb cleaner like Berryman's.

rider123 · « **Reply #2 on:** February 22, 2006, 02:19:16 PM »

If you wan't you could buy new plugs for the hell of it and see if that helps you out. I would check that you're getting spark on #2 cylinder like RED says.

pmackie · « **Reply #3 on:** February 22, 2006, 11:32:22 PM »

I'd look closely at the plug, plug cap and plug lead. I've seen lots of erratic misfires due to plug caps. Look for cracks, make sure the cap and lead are in good shape. Make sure the cap fits tight on the plug, etc.

socalbandit · « **Reply #4 on:** February 23, 2006, 01:22:27 AM »

I will check all that out. The bike is going to the shop tommorow to get the Race tech gold valves and springs, so I will have them test the coil and the resistence of the leads if possible. If they don't find anything I may just buy new coils and some Mikuni RS 36's

. I will at least wait until after I put my new jet kit in though. I like to replace the cheapest stuff first and work my way to the expensive stuff in the hopes that the cheap stuff is whats causing the problem.

rider123 · « **Reply #5 on:** March 01, 2006, 08:00:23 PM »

If it misfires less when hot maybe the pilot jet on that carb is a little dirty and making it lean? Do you have the mixture screws drilled? You could turn it out 1/8th of a turn on that cylinder just to eliminate that possiblility. The popping would indicate a lean condition, maybe a jet is gummed up.