Radiator fan

[Fishfried]

  The weather is great, snow is all melted, but the bike isn't running.  Only three cylinders are firing, I am guessing clogged jet but that isn't the real reason for the post.   

  The guy that worked on my bike before commented that the fan was wired to run when the ignition was on.  So the thermo switch was bypassed.  He reconnected the switch as it should be. The other day I let the Bandit idle for 5 minutes or so in the driveway and noticed the fan kick on, so the switch appears to be working.  Is there a reason for the previous owner to want the fan to run constantly, care to speculate? 

  Since I'm going to have the tank off to clean the carb should I check anything else, Dynojet website says to replace the thermostat for best results on the stage 3 kit.

  Here is a recent pic of my bike with the following new stuff: handlebars, bar end mirrors, grips, levers, new vinyl on then seats, cut the rear fender & relocated the license plate, shortened the rear turn signals. 

[El Gringo]

Could be that someone had just plugged the wrong wires together,

When i first rebuilt my bandit i accidentally connected the fan power to a switched 12V rather than the thermo switch, so it came on as soon as the key was turned.

[Chris H]

Ye could be a simple miss connection of the wires.

If you change out the thermostat be aware that the bandit one has small holes to allow water to bypass it when shut and a replacement might only have one air bypass, you would need to add matching holes to the new thermostat.

[Fishfried]

Good info, thanks fellas.  I'm going to get the bike back running again before I think about replacing the thermostat.

  Yesterday the bike fired up OK but after about 5 miles of stop and go riding it started running rough and quickly died.  After resting a minute it would start but only stay running with the throttle twisted a third of the way.  Every stop sign it would die.

  This morning before work I pulled the #1 plug and it was wet, blackish and oily.  I hit it with a quick spray of carb cleaner and very lightly brushed it off with a medium scotch brite pad.  Rested it on engine and it sparked like it should.  A nice splash of gasoline came out of the cylinder.  I put the plug back in (less than 30 miles on the plugs btw) and no difference.  Only runs with the throttle turned and rough at that. #1 pipe still cold. 

   Read a lot on the forum and petcock trouble, main jet clogged and fouled plugs come up a lot.  Should I try buying a new plug?  I have spark and gas splashed out when I cranked so maybe the petcock?  I'll try to find the thread on here on how to test it.

 

[El Gringo]

When you say gas splashing out of the plug hole, how much? Sounds like the float/float needle may be sticking open on that cylinder.

[Fishfried]

 

When you say gas splashing out of the plug hole, how much? Sounds like the float/float needle may be sticking open on that cylinder.

Maybe 5-6 drops, I'll check again tonight after work in better light and post what I see.

[greg737]

I "modernized" my Bandit 400's cooling system.

Gave it a 195 degree thermostat and a constant-bypass line just like all the modern bikes have.  This is a small diameter tube that connects from the thermostat housing to the radiator return line.  If you want to see it it's in my build thread.

It was an easy modification to accomplish.  No need to drill extra (OEM matching) bypass holes in the new thermostat if you install a constant bypass line.

[Fishfried]

When you say gas splashing out of the plug hole, how much? Sounds like the float/float needle may be sticking open on that cylinder.

In better light it was more like a fine spray or mist with a few bigger drops. Also a couple drops of fuel dripped from the pod air filter.

[Fishfried]

Stuck float.  Had to change the oil too, had lots of gasoline in it.  New spark plug too.  Running great!