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Old 07-18-2003, 05:02 PM
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Default Kawasaki KX powervalve set-up


Kx Power valve set-up, How too...
After needing help set-up my power valves i came across this helpful website i hope it is as helpfull to the guys on atm

This technical art is reprinted from Eric Gorr's book "Motocross and Off-Road Performance Handbook". For more info check out the author's web site
Kawasaki KIPS

Kawasaki’s KIPS exhaust valve system has gone through a steady refinement of design. Kawasaki uses a different system to suit the needs of the different model bikes. The earliest KIPS design used two drum shaped valves to control the flow of the sub exhaust ports. Opening the ports gave the exhaust port more time-area. The main exhaust port was relatively small with modest timing and duration. A rack and pinion set up controlled the drum valves, opening them at about 6,000 rpm. Kawasaki uses the rack and pinion design in all their KIPS systems except the 1998 and later KX80-125cc models. The 1992 KX125 and KDX used the next generation KIPS which featured a center wedge valve with two side drum valves engaged to a rack-and-gear actuating system. This system was very complicated with all its moving parts. The top and bottom racks had to be synchronized through the left drum valve, which has two drive gears molded in it. The drum valves are made of aluminum. When the drum valve becomes carbon seized, the steel teeth on the rack shear off the aluminum teeth on the drum valve, rendering the drum valve inoperable. Check the condition on the gear teeth every time you do a top-end service, because if one gear fails the whole system runs out of sync. . On the late model 80-125cc KXs, the KIPS is relatively simple relying on a wedge valve and flapper. This system is self-scraping so it requires little maintenance. In the first year of operation (1998) the KIPS system was plagued with failures like the pin breaking on the flapper, the valve receding into the cylinder and contacting the piston, and over-extension of the valve causing cock and jam. Pro-Circuit made an aftermarket valve cover with a full stop that prevented over-extension and in 1999 Kawasaki changed the wedge valve and flapper design for more rigidity and that solved all the reliability problems.

The drum valves on the 1988- 92 KX250 and 1990-2000 KX500 are also aluminum but have a hard-anodized coating that resists wear. However, the drum valves eventually wear at the drive channels for the center wedge valve, and the sloppy fit between the wedge and drum valves prevents the center valve from fully opening. That is why these bikes get noticeably slower as they get older. There is no preventative cure or aftermarket part. You just need to replace the drum valves when the drive channels wear out. The 1993 KX250 was the first year for the KIPS system used through present day models. The system uses a single wedge and flapper valve for the main exhaust port and two drum shaped valves for the sub exhaust ports. The valves are all linked together with two racks and pinions on the right drum valve and a steel gear on the upper rack linking the wedge valve. A left-hand-thread nut retains the gear to the rod that actuates the wedge valve. Check the nut periodically, if the nut loosens, the wedge valves become inoperable. The KX250 KIPS also features two large cavities to allow for dissipation of the compression wave that travels back up the exhaust pipe at low to mid rpm. Its important that the two valve covers on the cylinder be sealed with gaskets and it is normal for large amounts of black sludge to accumulate under those valve covers. It takes years for the sludge to accumulate to the point of adversely effecting performance. The only way to clean out the sludge is to have the cylinder hot-tank cleaned at an automotive rebuilding store. The 1993–2000 KX250 wedge valve tends to form burrs at the outer edges that face the piston. These burrs prevent the wedge valve from opening fully, and the thin flap that comprises the exhaust-port roof hangs out into the exhaust-gas stream, producing a shock wave that closes off the exhaust port. File the burrs smooth and check the wedge valve through the full range of movement. The valve pocket in the cylinder gets worn too. Aftermarket cylinder rebuilders like Max Power Cylinders apply a hard coating to that area to reduce wear or build-up material that has worn down from the moving wedge valve. Another characteristic problem of the KX250 KIPS is broken governor levers. The lever that transmits the movement from the centrifugal governor to the right-side case lever tends to break in half. This piece is located under the right side cover. If your KX250 suddenly loses top end power, its probably due to the actuating lever breakage or the carbon-seizure of the KIPS valves.

1988–92 KX250 and 1990-2000 KX500 KIPS Timing Procedure

The explanation of this procedure, written in the Kawasaki service manual, is confusing. It requires you to time the upper and lower racks at the same instant. My method of timing the exhaust valves is composed of simple steps that enable you to check your work as you go. The 1988–92 KX250 and KX500 use the drive-channel system to actuate the center valve. Here is the best way to time the KIPS on these models.

1. Set the cylinder upside down on a bench.

2. Install the center valve but don’t bolt it in!

3. Install the side drum valves and align the drive channels on the drum valves with the center valve, but don’t bolt it in!

4. Install the side drums valves and align the drive channels on the drum valves with the engagement pins on the center valve.

5. Lift up the drum valves so the bottoms of the gears are flush with the cylinder base. Take care not to disengage the center valve.

6. Slide in the rack from either side of the cylinder. Position the rack by installing the seal pack and pulling the rack out until it bottoms against the seal pack. This is the full-open position.

7. Drop the drum valves onto the rack so the valves are in the full-open position. Don’t pay attention to alignment dots or marks on the valve or rack just remember that the valves should be open when the rack is pulled out and closed when the rack is pushed in.

1992–97 KX125 and 1993-2000 KX250 KIPS Timing Procedure

The system used on the KX125 and KX250 uses both wedge and drum valves with racks. This is the best exhaust valve system for performance but the most difficult to maintain. Here are some tips for re-timing this KIPS system.

1. Install the wedge valves in the cylinder and the actuating rod and lever. Squirt some pre-mix oil on the parts.

2. Pull the wedge valve into the full-open position, place the gear on the end of the rod, and rotate the gear counterclockwise until the rack butts against the stop plate. Thread the nut on the rod and tighten it counterclockwise because it is a left-hand-thread nut.

3. Place the drum valves into their respective cavities until the top of the gears are level with the cylinder base. Now push the lower rack into place and bolt the seal pack on the rack into the cylinder.

4. Pull the rack out until it stops and push it in one millimeter; now it is in the correct position to install the drum valve. Before you push down the drum valves, make sure the wedge valve and drum valves are in the full-open position.

5. Push down the drum valve with the two gears first because it must engage the upper rack and lower rack simultaneously. Take care and be patient. You may have to wiggle the wedge valve yoke to get everything to fall into place. Never hammer the drum valves! Then push down the right drum valve and install the idler gear. Now install the bushings and check the system. The valves will bind and stick if you try to move the valves without the bushings installed, or if the cylinder is facing upside-down. Test the KIPS in this way, pull the rack outward until it stops, look through the exhaust port from the pipe side. The valves should be in the full open position. On cylinders where the base has been turned down more than .010 inches, the drum valve bushings will also need to be turned down to prevent the valves from binding when the cylinder is tightened.
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Old 06-03-2010, 09:42 PM
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can someone explain this in english, maybe draw it out for me with a red crayon and actually explain this, my problem is the bike runs first kick, stays running, can drive it all day long, but i have no low end, and no power band, done a compression test, everything is good, or can someone send me to a link with pretty picture so i know what i am looking at
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Old 10-09-2010, 12:24 PM
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Default power valve

you need to say which model you have i could photo copy the relevant bits out the manual for you?
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Old 11-09-2010, 04:23 AM
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Hey I have the same problem. I have a 1996 KX250. Can you copy the picture for me?
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Old 11-09-2010, 11:14 AM
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If you take your cylinder off and look at it as you read a print out this will mean a whole lot more to you. If you are still confused, get a parts printout from one of the online companies so you can name all the parts. I never do this any other time, but if you are still lost, then maybe you really should be taking yours to a shop. Honest, most all the instructions for anything are easier when the item is on your work bench.
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