Coaster Installation

A Step Beyond Marbling

Tag: exhaust

Where to begin. Ah! With mention that you won't gain a single horsepower or pound foot of torque by doing this. Still with me? Great! The only real purpose of removing the reed valves from the 1500/1600 Vulcan engine is to clean up the looks of the cylinders and get rid of some plumbing sitting on top of the #1 cylinder.

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A bit of background. Reed valves are mounted on the right front of the #1 (front) cylinder and left rear of the #2 cylinder. Their purpose is to inject air into the exhaust stream immediately after the exhaust valve which causes any hydrocarbons that escaped the explosion in the combustion chamber to burn. This typically creates a popping from the exhaust when the throttle is closed and the bike is decelerating. Most riders can't even hear the explosions with stock exhaust but with aftermarket pipes the constant popping can get rather annoying.

There is a simple fix for the popping which is referred to as 'marbling' the coasters. The instructions are on this Gadget page. If your only objective is to stop the popping and you want to keep all of your stock EPA equipment on the bike awaiting the day you trade it into a dealer (especially California where smog equipment must be on the bike for a dealer to resell in the state) then the marble trick is definitely for you.

If you don't give a hoot about trade in and would prefer your cylinders look like the second picture (below) then keep reading.

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#2 Cylinder With Reed Valve Assembly in place (stock). Note you can barely see anything on the other side of the bike. Also note hose attached to the top of the assembly.

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After Coaster Installation. Note you can see the exhaust pipe on the other side and the hose is now gone.

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The numbered parts in the diagram here are what you'll be removing with this modification.


What You'll Need

  • 1- Set of Coasters (aka block off plates)
  • 1- 12 mm socket and extension (to remove front and rear bolts on gas tank)
  • 1- 8 mm wrench (for removing the reed valves and installing new coasters)
  • 1- Long pointy pliers (needle nose)


How To Do It

  1. Remove your instrument cluster and gas tank. If you're not familiar with how to do this instructions are posted on this Gadget page.
  2. With your fingers or long nosed pliers, reach in and squeeze the hose clamps above each reed valve and slide them up the hose a couple of inches. Remove the hoses from the reed valve assemblies. The hoses will probably just slide off easily but sometimes a small flat blade screwdriver pushed under the base of the hose will help get things started.
  3. Using an 8 mm box wrench (if you have the ratcheting kind it'll make your life a lot simpler) remove the two bolts holding the front and rear reed valves in place. Notice on the 1500 Nomad/Classic the bottom bolt for the front assembly will come very close to the fan cage. It will clear the engine before it gets that far but just barely. Carefully remove the reed valve assemblies.
  4. Each assembly has two metallic gaskets. Chances are pretty good one of the gaskets stayed attached to the engine, the other is between the reed valve and the outer box assembly. If the engine side gasket didn't tear at all just leave it in place. If it tore you'll have to remove it (a razor blade works great) making sure you remove every trace of the old gasket from the engine. If you're using the outer gasket and it seems stuck to the reed valve, slide a razor blade carefully behind it and run the blade around the circumference. The gasket should come off without damage. If, somehow the gaskets were all compromised (not likely if you were careful) you'll have to buy new ones from your Kawasaki dealer.
  5. Mount the coasters (blocking plates) to the engine using one of the original gaskets and bolts supplied. You might choose to paint the bolts black. I'd suggest doing that the day before so the installation doesn't just wipe the paint right back off.
  6. With coasters mounted it's time to get rid of all the plumbing.
    1. Reach up on top of the #1 cylinder and pinch the hose clamp holding the hose that used to go to that cylinders reed valve pulling it toward the front. Now pull the hose off the air valve. That little flat blade screwdriver might come in handy.
    2. Do the same for the rear hose. Removing both hoses from the air valve will make removal of all the pieces much simpler.
    3. There's another large hose connected to the air valve and that's the one that supplies fresh air to the reed valves. It goes into the backside of the air box assembly mounted on your throttle body. On carbed Vulcans the hose plugs into a bib on the air intake crossover tube. For FI's, remove the air box cover and the back cover then push the intake air hose out the back of the assembly. You're going to have to plug that hole to keep unfiltered air from being drawn into the engine. Some riders just cut a section of that intake
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      hose, stick it in the backplate opening then shove a marble in it. Hose clamps on each side will keep the hose from going anyplace. Another, neater solution is to use a standard 1" hole plug as shown at right and available from any hardware store. The one in the photo happens to be chrome and was destined to plug the bottom of a bar stool leg before I got my hands on it. Bend the tabs inward just a hair if the plug won't fit all the way into the hole and test the fit. Use some gasket maker or silicone glue around the outer edge of the plug to assure a good seal and pop it into the hole. Once in bend the tabs outward again from the inside. You'll end up with something that looks like this
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      as viewed from the top/rear of the backing plate. Reinstall the backing plate and air box cover now or when you're ready to button everything back up. We've done this a little early just so your glue/gasket sealer can have time to dry. For Carbed Vulcans you'll need a large vacuum port plug to cover the bib on the crossover tube.
    4. With the large hoses removed you'll be able to pull the air valve out between the cylinder and frame. If it doesn't come out on the right side try the left. There's room but you may have installed aftermarket horns or something that crowded the escape route a little (grins).
    5. Once the air valve is free you'll find either wiring (1600 engines) or a vacuum hose (1500 engines) connected to it. Disconnect whichever you have and toss the valve in a box along with the old reed valves and hoses.
    6. 1600 owners, tuck the wiring away someplace safe and move to step 7.
      Annotated Throttle Body
      1500 owners, trace that vacuum hose back to your carb or throttle body and remove it. With FI bikes you'll really need those long nosed pliers now to reach the little tiny hose clamp tucked down between other plumbing. With that free use the pliers to pull the hose off the throttle body. Put a vacuum cap (supplied with the Barons kit) on the opening where the hose was. (See "To Reed Valve Plumbing" in the image.)
  7. If you put the air box or aftermarket air filter back earlier we're finished with the assembly. If you didn't, do that now. Put your gas tank and instrument cluster back on the bike and go ride without all these parts!

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As mentioned right at the top this mod isn't going to give you any extra power but your bike will sound a little different especially if you hadn't marbled the reed valves before. The different sound should not include any little ticky exhaust leak sounds. If you have those it means you missed some of the old gasket on one or both of your coasters. You can use a weak flame or stick of incense near the plates (engine running) to find the leak and fix it.

Hopefully you haven't been put off by all the detail. It has probably taken you nearly as long to read all this as it will to complete the project which is really very simple.

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