C model maintenance and setup tips

[kawagumby]

Hi guys,
I thought it might be helpful to have a thread that discusses C model tips to get the most out of the bike. Anyone with ideas on improving our experience with these bikes is welcome to chime in. With that in mind, here are a few I have based on the three bikes (86,87,88) I have owned over the years:

1. Swingarm

If you ride in rocks or fall over a lot, lol, the aluminum bracket that holds the chain guide will break off easily. Check out swingarms on ebay, nearly all are missing that bracket. The fix is to have the tabs that were not welded on the lower edge welded. This keeps the bracket from twisting in and breaking off.

2. Rear shock

The C model shocks are mounted upside-down compared to most bikes. The shock body is on the bottom with the shaft upwards. This creates a problem for mud and gook build up on top of the seal head just under the shock cap - which can corrode both the shock body and the shaft - ruining the shock. The fix is maintenance in the form of pulling the shock out once per season, removing the spring, popping the cap off and cleaning out the area above and around the seal head.

The rubber linkage protector is often missing or torn allowing mud and dirt from the tire to pelt the upper linkage and shock area...I wrap those areas with a piece of rubber inner tube.


3. KIPS

The KIPS actuating arm bolt on the C models is right-hand threaded, just the opposite of the E and H models - so beware.

When assembling the KIPS rod to the KIPS valves, it is very hard to see the rod grooves to allign them with the punch marks on the valves. I spray silver paint on the rod then quickly wipe it off leaving the silver in the grooves - making them easier to see during allignment.


4. Flywheel

The flywheels on these models can lose the magnets, so once per season check the flywheel by pulling it off and inspecting the epoxy glue that bonds those magnets. If they are starting to come loose, you can remove them and reglue with epoxy before it gets away from you. While checking the flywheel you can clean any rust up on the flywheel and coil plate, renue the gasket seal, and check the mag side crank seal for leakage (any traces of oil).

If the flywheel is ruined, you can replace it with an E or H model. To do so you will need a modifed coil plate, which Jeff Fredette sells for about $120 (as of last month).

5. Air leaks.

The carb boot (carb manifold) on these older bikes crack and leak air. You can get new aftermarket ones for about $100 or you can fix the cracked ones.
To do so, clean the boot thoroughly with solvent, then detergent, then acetone. Make sure all the cracks are opened for the cleaning process. Let dry completely. Use Sikaflex polyurethane cold-applied glazing adhesive to fill all the cracks without creating a buildup, then let dry overnight. The next day, apply a second coat with plenty of buildup in the areas that need additional mechanical strength. You will now have a strong leak-free boot. This stuff also works well for nearly any rubber on the bike including the airbox.

[KDXGarage]

Great info! I have a couple to add:

About 20 years ago (or more), Jeff Fredette sold an L-shaped bracket with triangular sides that was used to brace the chain guide mounting bracket. One was to drill two holes into the swingarm, then tap the holes and use red Loc-tite to mount the bracket with the two included 6mm bolts.

An FMF pipe gives the bike a good bit more power.

An aftermarket silencer or spark arrestor helps out in the weight and performance areas.

[Redrum]

thx guys...need all the tips i can get

[kawagumby]

DC plastics sells vintage plastic and parts. The carb boot is available there for 99.95. http://www.dcvmx.com

edit: The boot they sell has a smaller diameter and can handle the '88 Keihn carb - the '86-87 mikuni will fit also, the boot will stretch enough for the larger diameter.

[kawagumby]

KIPS Govenor:
The lock pins that hold the KIPS advancer (governor) together will fail over time. One end has a hardened steel pin the other has a bogus roll pin. I've just pulled apart two engines, a 1986 parts engine and the 1987 and both had failed roll pins. As long as the case holds the parts together, it shouldn't be a huge problem (other than the KIPS not operating to full potential and the possibility of the roll pin pieces doing some harm).
What I did on the engine I'm trying to get together (argh) was use a needle bearing roller to replace the inferior roll pin.
Why Kawasaki used a roll pin there is beyond my grasp...when I pulled the first engine apart I thought it was put there by a backyard mechanic...but nope, the same pin was in the other engine and had failed too.

[kawagumby]

Drain plug:

While I had the cases split, I noticed the drain plug threads were about ready to strip out. The drain bolt for the C models is shorter than that of the H models, so I wondered if extending the threads all the way through the case and using the H model drain bolt would work. It does...the H model length bolt tip will be nearly flush with the floor of the case and not interfere with anything. Extending the threads with a tap and using the longer H model length bolt will provide a much stronger connection and perhaps even a fix without the use of a helicoil.

[gopack4749]

2. Rear shock

The C model shocks are mounted upside-down compared to most bikes. The shock body is on the bottom with the shaft upwards. This creates a problem for mud and gook build up on top of the seal head just under the shock cap - which can corrode both the shock body and the shaft - ruining the shock. The fix is maintenance in the form of pulling the shock out once per season, removing the spring, popping the cap off and cleaning out the area above and around the seal head.

The rubber linkage protector is often missing or torn allowing mud and dirt from the tire to pelt the upper linkage and shock area...I wrap those areas with a piece of rubber inner tube.

When you were doing this rear shock maintenance did you take any pics? I am sure I need to do the same thing with my 87. I would especially like to see how you wrap the linkage with the inner tube. Thanks.

[kawagumby]

Here's what I did with this bike:
Instead of wrapping with inner tube, I used some reinforced poly (made from the mortar pans available at Home Depot) to make a std looking guard. The only problem I've had so far is noise; the tire will rub at times but once I got used to it, it doesn't bother me. I figure it'll last for about one season of good riding - the mortar pans are good for about 5 of these and cost $20.00 or so - you can cut them out with scissors. It is really strong durable material.

Regarding shock maintenance, there's nothing special about the KDX shock other than you can't really disassemble the clevis end - you need to take the rod nut off to replace the seal. Youtube has a few videos of guys taking shocks apart - so if you think you can handle a rebuild, check them out. As far as removing the dust plate, it's just a matter of using a chisel to gently open a space then use a screwdriver to pry it out completely.

[gopack4749]

Thanks for the response. I have already been checking out youtube on the shock maintenance. Good looking guard you fabbed up.