Learn why your carburetor is the problem and avoid the “Shut Gun” approach when it comes to figuring out what parts you need to get it running. There is so much to learn here, take advantage of it.
“MY BIKE HAS BEEN SITTING FOR A YEAR OR SO AND NOW IT WONT START. I THINK I NEED A TUNE UP.”
True.. but that WON’T fix your problem.
Being able to determine the purpose of your motorcycles “NO START”, or “POOR RUNNING CONDITION” will hopefully be what the main take away is from this post. But I would like to advise you to be prepared to have your mind blown when it comes to Gas, Carburetors, and the effect that time has on them when these two subjects are combined.
I want to start off by saying I am a BIG fan of carbureted bikes verse fuel injected systems. The idea of being able to dial in your air to fuel ratios with your hands and a couple of wrenches rather then a computer (if allowed), is what keeps me holding tight to this style system. Although, both have their pros and cons. One system can be more forgiving with the riders who store the bikes regularly and fire them up every couple of months (FI). The other tends to cost big bucks and aggravation when time gets the best of you and 6 months later you remember that you haven’t fired her up all winter (carb). I want you to keep in mind that BOTH require your consistent attention. Fuel injected systems can be just as costly when not taken care of. If not much, much more expensive.
Carburetors range in a wide verity of styles. From types like constant velocity or “CV”, to horizontal, straight slide and many more. Whether you have one, two, four, or even six different carbs powering your horse, ALL of them have some fundamental traits that you NEED to know. This will keep you from spending 300-1200$ a year, just to keep your bike operational and responsive. I want to give you knowledge and very simple steps to keep your bike running year round even when the odds are against you. When it comes to motorcycles carburetor set ups are typically ALL THE SAME. Each is designed to operate off one main combustible fluid: you guessed it-Gas-Fuel-Go Go juice. Whatever you call it, your motor needs it.
The problem with gas is that it contains ethanol. Without getting overly scientific with the benefits and problems of ethanol treated gas I’m just going to give you this single fact. Ethanol reduces the shelf life of the gas in your tank. It causes the gas to break down quicker depending on the amount it is contained in. That’s right, the smaller amount of gas your bike is holding, the quicker that amount tends to turn, or go stale. Why is this important? Your carburetor is designed with what is called a “Float bowl”. This allows a specific amount of fuel to be held readily available at the bottom of your carb for the jets to have access to every time you twist that throttle. On average your carburetor is holding about a shot glass of gas in its bowl. Now, you would think that that gas is in a contained airtight system, since carburetors are sealed in different areas. False. Atmospheric pressure plays an important role in the movement of this gas into your motors combustion chamber and is ALWAYS present. SO putting two and two together. Small amount ethanol treated gas vs time = problems. As gas begins its stages of going bad or starts to dry up bacteria begins to grow. This can either look like a thick sloppy layer of molasses or I’ve even seen it look like a bowl of crusty packed salt. Regardless, this process can happen quickly when the bike sits and fresh fuel is not flushed in and burned. The jets in your carburetor are specifically drilled to a certain size. The manufacturer has determined that to be the best possible rate at which they suck the fuel from the bowl like a straw. Keep in mind these jets are just big enough to pass hairs through your idle jet or choke jets. Main jets are always bigger and multiple jet sizes are used to help out in the fuel’s consumption and transition phases from idle, mid-range, to when you crack the throttle wide open in that favorite turn of yours.
As the gas turns and starts to dry it leaves this nasty varnish all over the jets’ openings and passages. Thus starving your motor of fuel due to the lack of flow available through these jets. This is exactly why using fuel additives and making sure you’re starting your bike weekly when not riding is so important. Fresh fuel flowing in and out of the carburetor allows for this process to never happen. What if I’m in the military, or going on a vacation for a long period of time? Excellent question. With this next tip, you will be ahead of the game every time when it comes to this problem.
Every carburetor is designed with a “Drain plug”. This screw located at the bottom most position on your carburetor directly on the “float bowl”. By turning your fuel valve off, and using (most commonly) a simple flat head screw driver you can drain the fuel inside of your carburetor. Simply crack this screw open and allow the fuel to drain onto the ground or container you have available. This secret is commonly NOT shared with you at your local repair shop. Why would they tell you information that would keep you from needing them time and time again? Carburetor repairs are considered the “bread and butter” of the repair industry. With this knowledge you are literally saving yourself thousands of dollars throughout the time you own your motorcycle.
Now, remember that the process of prepping your bike for storage or through the cold months isn’t fully completed until you suck or drain the remaining fuel from your tank. If this crucial step isn’t done, you will be allowing that old bad gas to flow directly into your perfectly drained carbs. The bike may run poorly, foul the spark plugs, and will cause a poor unclean burn inside your motor. This results in the lack of power and responsiveness of your bike.
Don’t be that guy who calls the shop asking for an explanation of your poor running bike that’s been sitting for months over the phone. The answers are here and by following through with these steps, I promise you the outcome will be much better. Like I said, shops cant wait for spring to hit so the bikes that finally get pulled out of hibernation are on a one way track to their benches.
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