It's Going to Happen
In one of our very first posts, we talked about getting ready for the first ride after your ATV has sat for a while. One of the things we talked about in that first post was the carburetor. We mentioned that if you do not either put an additive in the fuel or drain it completely, you risk facing issues down the line such as a varnished carburetor or plugged jets. Understandably, we take great care to ensure these aren’t issues in our bikes, but unfortunately that means that we weren’t able to provide you with any proof that it does actually happen.
But fear not! For every well cared for ATV, there is always at least one (although admittedly, this number tends to fluctuate) that has been neglected by an owner who didn’t even try. And lucky for you (not so lucky for us), one of our recently acquired bikes is in need of some love.You’ve seen him on our post about multimeters and he was our guinea pig for troubleshooting a starter solenoid, but we’ve never formerly introduced you to our 2000 Yamaha Grizzly 600.
We initially purchased the Grizzly with the intent of salvaging it for parts but once we had some time to do a thorough inspection, we were surprised that it wasn’t in too bad a shape. We thought maybe with a few minor repairs and some basic maintenance, we could find this bear a good home. (Can you tell my wife does the editing?) And wouldn’t you know it, the Grizzly needed to have the carburetor rebuilt. Just like that, we can show you proof of what happens when you don’t take care of your fuel. Sometimes instead of rebuilding a carburetor, I will pull one apart and try to clean it first. But, I have found that most of the time I can buy a rebuild kit for around $20-$30. One of the things I like to factor into buying a used ATV is my cost of labor. I work cheap but I still try to figure my time at around $35 per hour. Normally I would spend over an hour trying to clean out all the little holes in the jets (without making them larger) and still have gaskets that need replaced. So it works out in my head to buy a kit and just put all new parts in carburetor.
I started off this rebuild same as I would any other, by pulling the carburetor off the bike. The recommended way on this ATV is to start by pulling the front rack and fenders.
Next, I removed the fuel tank.
And just in case you’re feeling forgetful, make sure to turn the fuel line off before removing the tank.
At this point the carburetor was staring right at me. Removing it is simple. Just remove the front and rear clamps and pull the carburetor off the bike.
Once the carburetor was off, the first thing I did was remove the throttle cover plate.
To remove the throttle cable, I pushed the throttle down and held it in the wide-open position. While in that position, I was able to twist the little brass cable end counter clockwise.
This allowed the cable to line up with the groove so I could pull the cable end out of the throttle plate.
Then I removed the choke cable.
Once I had everything removed from the carburetor, it was time to get down to business. For some reason every screw on this thing was stripped and fighting me. When I finally was able to remove the two screws that hold the bowl on, I decided to cheat with the idle adjustment cable and unscrewed the whole thing.
Removing the bowl exposes the float, float valve, main jet, and pilot jet. Yea lots of stuff – Beth is convinced it looks like a brain. First thing out is the main jet.
Under the main jet there is normally a plastic or brass splashguard around that keeps the fuel constant. This keeps the carburetor from getting too much fuel when the bike is suddenly accelerated or stopped. This just pulls off… Next thing out is the float.
This is not a normal float. Normally it would have a pin across the top that you would push out to remove the float. When I pulled out the float it pulled out part of the float valve. I have always called it the needle; it hangs on the little metal tab on the float. Then I pull out the seat portion of the valve.
The needle and seat normally have a screw holding down the seat, but on the Grizzly it is an o-ring. After that I pulled the pilot jet out. I needed a small, thin screwdriver but didn’t want to walk all the way across the house and into the basement. My Gerber was already on hand it got the job done just fine.
The last thing I removed from the bowl area was the air-fuel adjustment screw. It is a good rule of thumb to turn it all the way in first, counting the number of turns to bottom it out. Make sure you remember or write down the number of turns so that you can replicate it when reinstalling.
Then I flipped the carb over and took off the slide cover and spring. This is pretty self-explanatory, but make sure that you do not stretch out the spring. The spring is set to let the slide come up as the engine is sucking more air. If you stretch this out, it will be harder for the engine to open will cause you to lose power.
Once I got the cover and spring off I took out the slide with the needle.
On the slide there is a needle that comes out the bottom. If you turn the slide upside down, the needle should just fall out. Now pay attention to the top of the needle. There is a small metal washer, a plastic ring, and a little e-clip in a notch on the needle. Just like the air-fuel adjustment screw, you’ll want to take note of what notch your clip is in. (We included the old needle and the new needle in the photo below.)
Last but not least, this carb had a little jet in the front of it that gives an extra boost of fuel when you hit the throttle.
Well, I thought it was the last part; one more reason to take a good look at your rebuild kit as you are working. When I looked at the new kit, I saw this long tube with some holes in it…
It turns out that the guide for the needle is replaceable in this carb. Not too many are removable so this was a new one to me but very simple to do. Just tap on the end with a hammer very lightly and it should come right out.
Once you have the carburetor out and tore down, you might as well give it a good thorough cleaning. Carburetors have holes and passageways all over so what I like to do is take a can of carb cleaner, put the straw on it, and go to town. I put the straw in to every hole that I took a jet out of and spray. Then I look to see if the cleaner is coming out of any ports in other areas.
Be warned that this will splash back at you so make sure you are wearing eye protection (and/or that your wife doesn’t get too close with the camera). After I got the main body cleaned I moved on to the bowl. Now this bowl was full of algae. Yes, algae will grow in fuel… sort of. Here’s some biology, physics, and a bit of chemistry for you to chew on… When there is water in the fuel, the fuel floats on top of the water. Because they separate, this allows the algae plenty of room to grow in the lower space, which contains only water. The algae growth was pretty bad so I cleaned and scrubbed on the bowl for a little while, then I filled the bowl with carb cleaner and let it sit.
While this bowl was sitting I started to re assemble the main body. I like to cut the very top of the package off the kits so I can save them. It helps to leave the tag on them so you know what kit it is. You never know when you may need one little piece out of one of these kits. After I cut the top off I take all new the parts out of the bag and make sure they are the same as the old. The jets have a number stamped on them -- unless you want to go back to stock you will need to keep the same jet numbers. The numbers were such fine print that we weren’t able to get a photo. In fact, Beth wasn’t able to see the number on the old jets at all until they were good and clean (even though they were being replaced). Once I made sure my numbers were all the same, I started to install the new parts. You’ll want to make sure that every thing that came out gets replaced or reinstalled, but don’t panic if you have new parts that don’t get used. The kit we purchased for the Grizzly covered years 1998-2001; since our Grizzly is a 2000 model, it doesn’t have the exact same carb as a 1998, 1999, or 2001 model. Just because a rebuild kit covers the right year for your bike doesn’t mean you need to use all of the parts included. When I started reassembly, the first two things I tackled were the two most detail oriented parts: the air-fuel adjustment screw and the slide needle.
Like I said before, you really need to remember where the air-fuel adjustment screw was when you took it out. If not, the service manual can tell you how to adjust. If you don’t have a manual, a good starting point is two and a half to three turns out from the bottom, but this will need to be fine tuned if you do not have the exact number. Trust me, it’s easier to just write it down. When I started working on the new needle for the slide, I actually moved the parts straight from the old needle to the new one, that way I would be sure they were going back on in the exact order and in the exact position they came off. Most of the time the kits come with all three of these parts (a small metal washer, a plastic ring, and a little e-clip) but my kit did not have the plastic washer so I had to take it off and reuse it. My clip was in the second notch so I moved the clip to the second notch on the new needle and slid on the plastic washer and the metal washer.
Then I put the needle back in the slide and put it back in the carb body. Next to go on was the top cover and spring.
Once I had the more detail-oriented pieces back into place, I just continued replacing each of my old parts with the new parts from the kit. The main jet, pilot jet, the seat and needle, the float, and the extra jet I just learned I had.
At this point the bowl had been soaking in carb cleaner for a while. I dumped the cleaner and scrubbed out the algae. It takes a little work but it will come off. Then I put the new bowl gasket on and reinstalled the bowl on to the carb body.
Now that the carburetor was back together, I just needed to reinstall the cables. I started with the the idle adjustment cable…
Then I put the carburetor back on the bike and reinstalled the throttle and the choke cables.
And of course reinstalled the throttle plate cover.
You can’t see the gasket in the photo, but don’t forget it when you put the throttle plate cover back on! When you’re putting on the intake boot and the engine boot, make sure to look for any cracks or tears. These will cause the engine to get extra air and will cause the bike to run lean. Once you get the boots back on it is just a matter tightening up the clamps and reinstalling the fuel tank, fenders and rack. The thought of rebuilding their own carburetors intimidates a lot of people but there’s really nothing to it. This job didn’t take long (less than an hour with my wife standing over me taking photos) and it didn’t cost much either. The key is to take your time. Pay attention to the parts you are removing and reinstalling and you should be fine. And like we’ve said before, your user’s manual is your best friend. If you’re still stuck, don’t hesitate to send us an email us here. So tell us… How bad was your worst carb rebuild? Do you have any photos? Did I miss any steps? Do you have any tips? We would love the feedback.