How to Fit a Jet Kit

Remove the fairings and the fuel tank as per the maintenance section of your owner’s manual. Remove the air box retaining bolts and the crankcase vent hose. (3145)

3145

Remove the remaining bolts in the air box and remove the air box bottom. (3144)

3144

Take note of where hoses and plugs go and remove them. (3128A – 3131A)

3128A

3129A

3130A

3131A

Look at the bottom front of the carbies. Find and undo the manifold clamps. They are keyed so won’t move once loose. (3140)

3140

Carefully pop the carbies out of the manifolds.  Remove the choke cable and the throttle cables. To get the throttle cables off, and on again once your done, loosen the cable holder bolt so the holder can be moved around. (3143)

3143

Once the carbies are on your work surface take note of roughly how far in the idle screw is and remove it being careful not to lose the spring. (3142)

3142

Unscrew the trumpet screws and remove them and their plate. (3141)

3141

To change the needles and springs remove the two diaphragm cap screws. (These and the bowl screws will probably be tight so something with a rattle action will be extremely helpful.) Then remove the cap and underneath you will find the slider spring. (3132)

3132

Remove this and then carefully remove the diaphragm and slider. (3134 & 3136)

3134

3136

Don’t lose the o-ring on the vacuum port. (3135A)

3135A

With a pair of needle nose pliers grab and remove the needle retaining cap. There is a small spring directly under this that may come up with it. Don’t lose it. Tip the slider upside down. As well as the spring will fall out a washer, the needle and a spacer. (3137A)

3137A

Installation is the reverse of removal. When you replace the needle retaining cap you must push firmly till its home, but don’t shove. Breaking the holding tangs will cost you about $100.

Place the slider back into the carbie body. Don’t worry; it can only go in one way. (3135)

3135

Make sure the edge of the diaphragm is in its groove and you haven’t lost the o-ring.

Put the new spring in, pop the cap on and screw it down.

To change the idle and main jet turn the carbies upside down and remove the bowl screws and bowl.

Inside is your float, main jet and idle jet. (3138J)

3138J

The jets are slotted and unscrew normally. Change the jets to the desired sizes.

The next thing is to set the float height. With all bowls off tip the carbies so the floats fall away from the carbies. Then slowly tip the carbies so the floats just contact the float needles. (Tipping them too far will depress the needles and give an improper reading.)

Set the float height from the gasket surface to the heel of the float using verniers or a special float height measuring tool. (3138F) put the bowls back on.

3138F

Finally, set the idle mixture screws to their recommended setting.

For this kit it is recommended that the fresh air valve be removed. So I bunged the two vacuum lines from the centre carbies and joined the exhaust port hoses together.

Put the trumpets and their plate back on. Screw the idle speed control back in.

Place the carbies on top of the manifolds and reattach the choke and throttle cables. Pull back a slider so you can see a butterfly and check the throttle action.

Push the carbies back into their manifolds and tighten the clamp screws. Put any hoses and wiring back on the carbies.

So the bike wouldn’t have dry carbies for its first start I put a bit of hose on the fuel inlet, got a large syringe and pumped some fuel back into the carbies. At this point you can also look to see if anything is leaking fuel. Reconnect the fuel line once you think all carbies should have a little fuel in their bowls.

Re-install the lower, then upper air box and filter. Pop your tank back on and you’re ready to start.

The idle speed is likely to be way off, so be ready to turn it down when you start the bike.

Most of the time the jet kits are pretty accurate as far as what jets go for which setup. But if up top the bike is good when partially heated up then goes a bit dowee when at full temperature, then the main jets are too rich. If the opposite happens then they are too lean.

Similarly in the midrange if you have a richness problem you need to lower your needles and vice versa for a lean condition.

A rich condition when full throttle around 2-3k is used is caused buy a too high float level and too lean too low. The float height also determines the mixture for cruising. This is where it gets confusing, if the mixture is rich you need to increase the bowl to float figure because you are working on the carbies upside down. The opposite of corse applies if things are a bit lean.

Lastly is the idle mixture. If you blip the throttle once warmed up and the engine dips for a second the idle mixture is too rich and too lean if it hangs. (3138S) If you don’t have a vacuum gauge then you will need to take the bike in for balancing of the carbies.

3138S

Many thanks to Darren for the Jet Kit Guide!