Join Date: Aug 2013
Location: Vancouver Island BC
Weak rear cylinder. Backfire, surging
I could use a little help diagnosing an on going problem with my 1100 V Star.
This entire riding season I've been having issues with my bike backfiring and surging at a constant speed. Runs good when I'm on the gas hard, but if I'm just trying to cruise at a steady speed it runs like crap.
I also used to start it when cold by pulling the "choke" about 3/4 way out and it would fire up. Now I have to keep cranking it until it catches and slowly add some choke while cranking. It also doesn't idle as high as it used to with the choke out.
Here's what I've done in my hunt for an answer.
Changed plugs. (old ones looked good but were old)
Changed Fuel filter
Ran several tanks with Seafoam
Synced carbs several times.
Yesterday i removed the carbs and cleaned them. They weren't really bad inside at all.
Checked plugs and double checked for correct gap. Plugs are good and so is gap.
Synced carbs again.
Tonight on the way home it's surging and backfiring.
When I got home I felt the pressure from each pipe.
Front cylinder is a strong steady pulse.
Rear cylinder is weak and is the one that backfires.
I have a bike trip planned for next week and I don't trust my bike right now!