Split the cases to check a used kdx?

[1911user]

I'm trying to determine how far to go in checking out a new-to-me 90 kdx. I'd like to be thorough but not do alot of work for nothing. The history of the bike is it's sat unused for most of it's 15 years with some riding and maintanence every few years. The only mods are aluminum handlebars and removal of the lights and odometer.

The compression is 180 psi with the engine cold.
The oil is milky, so I'm replacing the waterpump seal (and shaft if grooved).
I'm going to pull the head to check/repair the KIPS valve system and inspect the top of the piston and ring.
I'm also going to pull the airbox, carb, and reeds to check/clean as needed.
I've ridden the bike some and the tranny seems fine except it doesn't want to go into neutral when the engine is running. This is with new oil. I'll flush the tranny before riding it again.

Would you go any further in the engine than pulling the head and replacing the waterpump seal? Anything you'd check on the clutch assembly?

 

[ScottS]

I would only split the cases if you intend to repllace the crank, bearings and seals- no reason to do all that work just to put the old parts back in.

Shifting problem may be bent shift forks or just wear- it is an old bike. Flushing is hopefully going to loosen things up

It may not want to go into nuetral if the clutch is not fully disengaged, check the clutch basket, the tangs that the clutch plates ride in my be grooved or notched, some say thay can be filed smooth , but if you can afford a new clutch basket that may help with the shifting problem.

If you can get someone to do a leak down test on the engine that will tell you how the crank seals are .

Milky oil could be the head gasket or the base gasket too.But is usually the water pump.

 

[dirt bike dave]

What new tranny oil did you put in? On my old KDXs, if I used heavy gear oil and the motor was not hot, they would be hard to get into nuetral. You might try changing the oil to something light like Type F ATF.

 

[1911user]

The first change was 10w-40 conventional oil. I put in a little over the 0.8 Liter specified so I changed it again the next day to 5W-30 conventional and it still didn't want to go into neutral when warm/hot. It slipped into Neutral easy when the engine was off but still warm. Both oil changes were somewhat milky from riding 1-2 miles around a suburban neighborhood, but not as milky as what the bike had originally contained.

FWIW On the last 2 short rides, I adjusted the air screw and started to feel some of the power in the bike. Barely rolling the throttle caused it to surge ahead unlike before; nice! The air screw was out 2 1/2 turns before making a noticable difference, I'll try a smaller pilot jet after the bike is back together.

 

[JasonWho]

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[dsndblm]

Try Bel Ray Gear Saver for the shifting/neutral problem. I almost bought a new clutch and tried the Bel Ray in a last attempt, cost $6 instead of new clutch.

 

[WildBill]

Sounds like you're on the right track. I had to have the cases split to have a new con-rod, bearings & crank seals installed in my '90. I was getting trans oil in the airbox thru the breather. This was caused by the tranny being pressurized by blow-by thru the crank seals. New seals fixed it. The only sure fire way to find neutral on a bike that I've found is to try and shift from 1st to 2nd on a nasty, rooted, muddy uphill climb. Works every time. Good luck with the "new" bike and keep us posted.

 

[JasonWho]

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