Carb Tune Up Part 1: Post Winter Storage


So you pull your bike out of storage after the snow starts receding, put the battery back in and crank it over with excited anticipation. For the last 4 months, it has been in the garage quietly waiting for spring’s arrival and after firing it up, has some bogging issues at 0-1/4 throttle. If you’re many others out there and didn’t drain the gas tank or put fuel stabilizer in it, you may run into a similar issue. Most of the time you will still be okay with the same gas, but in many cases it can have problems problems after sitting dormant all winter.

When gasoline evaporates or sits for a long time, it can cause a gummy varnish type build up inside the carburetor. You might be okay for a few winters, but eventually it will catch up with you and the build up will be enough that the carb needs to come apart and be cleaned.

How do I know if my carb needs cleaned or if it needs to be rejetted?

If your bike ran fine before you parked it for the winter, and now when you run it has issues (bogs down with throttle, won’t idle, etc), chances are you need a carb clean. If you had issues for awhile before now or you changed something on your bike that might affect the air/fuel ratio (aftermarket air filter/exhaust, carb changes, etc) then you may need a carb adjustment. Stay tuned though as we’ll cover carb adjustments in part 2 of this guide.

Signs of gummed up carburetor(s)

  • Poor or no idleDirt Carburetor
  • Engine bogs down in 0-1/2 throttle range
  • On multi-cylinder bikes: One cylinder is not firing at idle (pipe should feel warm right after start up)
  • Only idles or runs better with choke on even after warmed up
  • Bike won’t start

What to try first

  • Drain tank and carb of old fuel and try new fuel (could be water or bad fuel in the carb)
  • Run a fuel treatment/cleaner in gas (heard great things about techron)
  • Change/inspect spark plugs, fuel filter, and air filter
  • Check exhaust for obstructions
  • Check that there are no air leaks around the carburetor that would affect air/fuel mixture
  • Some have great luck with cleaning the carb without removing it by draining the float bowl and adding Techron (or similar cleaner) to carburetor float bowl through fuel hose and letting it soak for a few hours, then draining and running normal after that

Remove and Clean!

Carburetor main and pilot jets
Remove both the pilot and main jets and clean thoroughly

So you’ve narrowed it down to a gummed up carburetor. The next step now is to pull off the carburetor(s) and get to work cleaning those suckers. Every bike is slightly different so I’ll let you refer to your owner’s manual as to the best way to remove them. In a lot of cases you can get away with removing the top and leaving the throttle (and choke cable if you have one) cable attached. Once you have removed the carburetor, it’s a good idea to remove anything that has rubber in it like the float needle, as carb cleaner can start to break those down. The most important things to pay particular attention to are the small passages and jets, especially the pilot jet since it is smaller and can get plugged easier. If you have a parts basket/cleaner, you can let the carburetor and parts soak in there and let it eat away all the varnish that has built up in the carburetor (make sure to remove the float bowl and jets). If you don’t have access to a parts bath, you can clean the carb by hand which works fine, it will just take more work. You may also use the float bowl as a make shift parts cleaner and place the unscrewed jets in the bottom of it and fill it with parts cleaner. Make sure the little holes on the side of the pilot jet are clear and you can see through them. You should also be able to see all the way through the middle of the pilot jet (although it is a pretty small hole) and main jet. Make sure there is no gunk in the bottom of the float bowl as that can restrict flow through the main/pilot jets. Also make sure to clean out the small holes by spraying carb cleaner inside each of them with the straw attachment.

Cleaning Tips

  • Dunk in parts cleaner or spray down with carb cleaner but be careful to remove rubber and plastic parts as it may corrode them
  • Boil carb and jets in water or lemon juice for 5-10 min for the best clean (make sure to rinse and dry completely immediately afterwards and spray down with carb cleaner to remove all water)
  • Use strands of wire, old toothbrush, or pipe cleaners to clean small passageways and jets (be careful when using metal wire as it can deform or scratch carb parts)
Carburetor Float Bowl
Clean Float Bowl

Once all the passageways are clear and everything looks clean. Inspect everything one last time making sure to make sure the float pivots freely, the slide and needle valve are clean, and the jets are squeaky clean.  Now carefully put everything back together including a new float bowl gasket. (We recommend an OEM gasket set) Make sure your hands are clean as you maneuver the slide in place and twist throttle once in place to make sure it slides smoothly. Also make sure that when you put the carb back into the intake boots(s), that it is securely sealed so no air can leak into the carburetor or engine. If you need to replace screws, jets, or any parts along the way, you can view our OEM parts finder if you need help getting everything back together or need to replace any screws or carburetor parts.

Motorcycle Ride Once everything is back together, turn on the gas valve and let the carb fill up with gas. Check for leaks on the float bowl or drain tube (carefully tap on side of carb if the float is stuck to free it). If everything looks good, fire that baby up and enjoy the purr that comes from an engine with a newly cleaned carburetor. If cleaning the carburetor didn’t fix your problem and you’ve had the issue for a while, then tune in to our next blog post regarding jetting your carburetor!

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