My Jackal/sidecar rig (46K mi) has had a low speed misfire for quite a long time. It was annoying but not terrible--the misfire felt like it was on one side, and the mpg was low, in the low 30s. From time-to-time, I’ve tried to figure out what was causing the problem. I reset the valves & TPS. I replaced the plug wires, caps and plugs. I have a donor bike, so I tried switching out the ign coils. No joy.
I finally decided to take a look at the injectors, so I pulled the airbox* and removed the throttle body/injector assemblies. The left TB butterfly was sooty, much more than the right one, so I think that was the side with the misfire. The excess carbon went all the way thru the plastic pipe that connected the TB to the airbox.
I cleaned the TB/injector assemblies from the donor bike and installed them in the rig. I figured I might as well replace the FI hoses and fuel filter while the tank and airbox were off, so I did that, too. I think I replaced nine hoses in total, a fiddly job I’m glad I won’t have to do again for quite a while.
I went for a couple of shakedown rides, and the misfire is gone; the bike seems to have more power and feels smoother. In the end, I think a faulty injector probably was the root cause of the problem. I may send the injectors off for cleaning and refurb so I’ll have a set as spares. That could also confirm whether there was a bad injector.
*Airbox--what a pita. When you remove it, the instructions I followed didn’t mention the little nipple and hose on the LH side. If you don’t take the nipple off, you can’t get the damned thing out. The only way I could get the airbox out was to first remove the rubber couplers that connect the TBs to the airbox pipes, then remove the pipes, and finally pull the airbox out. This is not how the instructions said to do it. “Installation is the reverse.”
The instructions also indicated that you could take both TB/injector assemblies out as a unit, connected together. That didn’t look like it would work, so I took them out individually. Finally, I read somewhere that the resistance for the injectors is 12 ohm, but all four of mine were a hair over 17.
Rich A
