I was heading home for lunch last Tuesday when my bike suddenly got real sluggish. It would almost die every time I tried to pull away from a stop. I’d have to hit 4000 rpm on the tack and slip the clutch to get moving. The engine would easily go to 9000 in neutral with no load, but it just didn’t have any power.
When I got home, I started checking and it looked as though the engine wasn’t hitting on its two back cylinders. This engine is a V-4. The pipes coming off of the back two cylinders were cold. I just figured I’d lost the back coil. I had another bike to ride so I planed to switch off and look at this one the following Saturday. (That turned out to be different sad story.) The battery was a little low. I was only showing 12.5 volts with the engine running at 4000 rpm. It would actually jump up to about 13.5 volts when I dropped the engine to 2000 rpm. The battery seemed sluggish so I hooked up the charger and gave it a good, deep cycle, 2 amp charge overnight.
(Side note here. Both battery and regulator are only about two years old.)
Saturday I go out to fix the bike. The first thing I want to do is confirm that I don’t have fire at the back two cylinders. I fire it up and sure enough it runs rough, just like it did on Tuesday. But when I check to see which two cylinders aren’t hitting, it’s now the left rear and the right front. I pull the back plugs out and check for fire. The plugs look good. Dry with a little black residue. Not chocolate, but dry with no clumps, and I have fire at both plugs. Those front plugs are rough to get to. You have to pull the radiator to get to them, so I decided to start the engine again and make sure which cylinders aren’t firing.
With this tank of gas, I’m on the second half of a can of a gas additive that is supposed to remove carbon build up. I’m starting to think the gas additive may have loosened something that’s plugging up a gas line, or jet in my carburetor. But before I start pulling the carburetor off, I want a final check to be sure. Those plugs on the back cylinders looked good to me. Also, I’m smelling gas at the tail pipe. Doesn’t that mean I’m getting gas, but no fire?
I put the bike back together and start then engine. When I run it up to 8000 rpm, it starts to backfire and blow black smoke. The tach starts to jump every time it backfires. I just hold the engine speed there for a while while it spits, pops, and blows smoke. It eventually settles down and holds engine speed without backfiring. The smoke clears up too. I grabbed a helmet and put a couple of miles on it right then. It fires off the line and hasn’t missed a beat since then. I’ve been riding it as much as I can since. It’s running as well as I ever remember. Additionally, the battery seems to be holding the charge.
I haven’t really “fixed” anything so I’m still a little skittish, but it’s running good at the moment, and I don’t want to start monkeying with it. I’ll keep riding it to work and to the store until it either starts acting up again or until I trust it again. In the meantime, I’m just riding on faith.
— Guy Wheatley