Removing Carburetors and Replacing Pilot Jet on 2007 Bonnie

So here it is. A step by step instruction on how to rejet the 2007 Triumph Bonneville when installing the D & D mufflers. Newbonneville.com provides a size 45 pilot jet and a set of instructions on how to install it.

#45 Pilot Jets

Unfortunately the instructions that came with the pilot jets are confusing at best.

I decided to perform the job myself with the help of my Haynes Service Manual and by reading carburetor maintenance threads in triumphrat.net. The Jenks Carburetor tuning kit instructions was also helpful in providing some insight into the process.

The instructions are really two parts. The first part is removing the carburetors. This is what took most of the time. Actually changing the pilot jet was the easy part.

Removing the Carburetors

Be for warned, this process involves removing the carburetor. I know this sounds extreme just to install a new pilot jet. But it was worth it because I think it would have been much harder to perform the work while its on the bike. Also, I wanted to change the Pilot Mixture Screw (not to be confused with the Pilot Jet) with these idle mixture screws from newbonneville.com. Another reason is to clean the grease that had accumulated on the outside of the carburetors. I had been ignoring an oil leak from my cylinder head that had been spraying oil into the carburetor (you'll notice this from the photos). This job is easier to do with the carburetor out of the bike.

Remove Seat, Side Panels, and Battery

The first thing you have to do are the following:

• Remove the seat
• Remove the left and right side panels
• Remove the battery

I am not going to provide instructions how to do the above steps. These are pretty trivial and you can find these instructions in your bonnie's users manual.

Remove Gas Tank

Next, remove the gas tank. Remove the two bolts(#10) that are holding the gas tank to the chassis.

#10 Bolts Secures Gas Tank to Chasis 

Before lifting of the tank, close the fuel tap and remove the fuel hose from the fuel tap. You will need a needle nose pliers to loosen the clamp of the fuel hose while you pull it away from the fuel tap.

Fuel Tap with Fuel Hose Secured with a Clamp

As you lift the fuel tank out, reach under the right hand side and detach the breather hose from the gas tank.

Detached Breather Hose from Gas Tank

Remove Air Filter Housing Bolts

Next, remove the bolts from the air filter housing (this is where the battery usually sits). Remove the four bolts indicated by the arrows shown on the photo below:

Air Filter Housing Showing Four Bolts to Remove

This should provide the give necessary when its time to remove the carburetors.

Detach Wiring Connections

Next, detach all wiring connections:

• Heater connectors for each carburetor
• Throttle Position Sensor (TPS) wiring connector located under on the right-hand side just above the fuse box

Left Side Heater Connectors

Right Side Heater Connectors

TPS Wiring Connector

Remove Carburetor Breather Hose (Optional)

This next step is optional. Remove the rubber hose that is connected in the middle of the carburetors. You can leave this in, just make sure you carefully snake out the cable while removing the carburetors. I removed it because it made removing the carburetors easier.

Rubber Hose Connected to Middle of Carburetors

Slacken Rubber Hose Clamp Screws

Next, using a flat head screwdriver, fully slacken the two clamp screws that holds the rubber hose that connects the carburetor to the cylinder head from both sides of the bike. Make a note the orientation of the clamps.

Left Side Intake Hose to Cylinder Head

Right Side Intake Hose to Cylinder Head

Next, using a #3 Allen head driver, fully slacken the clamp screws on the rubber intake that connects the back of the carburetors to the air box.

Left Side Clamp Screw on Intake Hose to Air Box

Right Side Clamp Screw on Intake Hose to Air Box

Detach Throttle Cables

Finally, slacken the throttle cable lock nuts and disengage the throttle cables. Be careful when doing this as to not fray the cables. Also make a note on which cable to goes to which link.

The Big Push

Now you are ready to remove the carburetors from the bike. This is where the Haynes manual really helped. A bit of elbow grease and steady hands will get you through it. This is not a simple process, but its doable by following the steps herein. 

1. Push the carburetors back and ease them out of the cylinder head intake rubber. The air box housing should give since you've removed the four bolts that was holding it in place.
2. As the carburetors past the edge of the rubber, draw them out towards the left side of the bike. The Haynes manual recommends removing the left rubber intake from the cylinder head to make room for the right carburetor to pass. But I found that this was not necessary. 
3. Once the front of the carburetor is freed from the intake rubber, the rear intake should easily come out. Push the carburetors down to help get it pass the rubber hoses.
4. The carburetor should be freed up at this point. Now with a slow and steady motion, push it out towards the left side of the bike. Be careful when you pass the right carburetor on the left intake rubber.
5. Be careful when handling the carburetor because there is gasoline inside the float chamber that could spill out.

Carburetor Removal as Viewed from Above

Carburetor Removal as Viewed from Right Side of Motorcycle

Carburetor Removal as Viewed from Left Side of Motorcycle

Congratulations you now have a bouncing baby carburetor. Well not quite, but didn't it feel like you were birthing one.

Carburetors Out of the Motorcycle

Make sure to stuff the intakes with rugs so nothing accidentally falls inside them.

Now you are ready to do replace the pilot jets.

Replacing the Pilot Jet

At this point, now that the carburetor is out of the bike, you can pretty much do whatever you need to do with them. Put the carburetor in a plastic pan to work in.

Drain Gasoline from Float Chambers

The first thing you have to do is to drain the gasoline out of the float chamber. You can do this by slackening the bolt on each float chambers located under each carburetor.

As you can tell from the photos my carburetors were very dirty. I cleaned it using a rag and the gasoline that I drained. I replaced the eight screws that held the carburetor top and bottom covers with sturdier ones available from newbonneville.com. I also replaced the pilot mixture screws with tool-less ones also available from newbonneville.com. This handy gadget will make idle adjustments easier. More on this later.

When performing this task, I recommend doing it to one carburetor at a time.

Remove Chamber Cover

The first steps is to unscrew the four Phillips head screws from the bottom cover of the carburetor. 

Remove the cover to reveal the jets and float.

Left Carburetor Viewed from Below

Replace Old Pilot Jet

So basically all that is needed is to unscrew the pilot jet which is seated way down in a narrow chamber. I hit a snag here because I thought I had a narrow screw driver that would fit in this chamber. I didn't so I had to take a trip to a local Sears. I found a Craftsman Cabinet Tip 1/8" x 6" screwdriver that fit just right. 

The pilot jet needle is on tight so you have to give some muscle to screw it out. Once it is loose, turn the carburetor down to let the old pilot jet needle out. Take the new needle and screw it tightly in place. Now screw back the cover in place and you are done.

Adjust Pilot Jet Air Mixture

The last thing you have to do is adjust the pilot air mixture. You'll need a special tool called a D-Tool to perform this task. Newbonneville.com provides such a tool. First turn the air mixture screw clockwise all the way in to reset. Then turn it fully three times counter-clockwise.

Perform the same procedure to the other carburetor.

Putting it All Back Together

The biggest trick really is being able to put everything back in place. The toughest part is putting back the carburetor. When putting back the carburetor, do it starting from the left side of the motorcycle. It is helpful that the air box is not screwed down so you can push that back and give room for the carburetor to slide back in. Be careful when sliding over the rubber intakes. Once I have the carburetor back in place, I slid the front intakes into position first and then position the rear intakes. Make sure the rubbers are fitted well around the carburetor openings and they are not pinched. Bolt down the air box once all the intakes are positioned in place. Tighten the clamp screws. I worked on the front ones first. For the rear ones, I held the rubbers in place while I was tightening the clam as to avoid the rubber from slipping off.

Reattach the throttle cables in place. Make sure the right cable is attached to the proper linkage.

Connect all the wires which includes the heater connectors and TPS wiring. Put back the carburetor breather hose if you decided to remove it.

Put back gasoline tank and attach the breather hose and the fuel hose. Turn the gasoline tap back on. Finally, put back the seat.

Checking Out Your Work

Obviously the proof that everything works is by simply turning over the engine. First turn up the throttle to make sure there is gasoline in the carburetors since they were drained. Turn on the ignition and hope for the best .

Also check to make sure that the throttle cables are on correctly by turning the handlebars left and right. The engine should not rev when you do this. If it does, then you will have to make some adjustments to the throttle linkage connection.

Finally, go and ride your bike and check out its new found performance.