Update on my '90 200...............

Marsh

Member
Feb 26, 2004
38
0
For some of you who have been reading my posts lately I have a '90 KDX 200 I bought last month and have been trying to tune it in. It was running very different compared to my buddy's '03. Like, I mean, night and day different!! :cool:

After doing a WOT and 1/2 throttle plug chop I noticed a severe lean condition in both instances while the plug was fouling real bad while riding in the low revs around the house. I couldn't figure it out!

A friend said to check for air leaks. I sprayed penetrating fluid around all the seals, rubbers, gaskets with no changes.

Then, I took the mag cover off and it was full of oily gas. About a tablespoon full. Crankseals :eek: finally I found something that could cause my ailments.

So. I ordered both seals and began to tear out the mag and stator to hopefully pull them out from the sides but there are casting 'nubs' at the seals to prevent them from blowing out so now I realize I have to split the cases.

Let me nut shell this for you, I think I'm rambling.

The head was flawless, BUT
both the Kips valves were in four or five pieces each with most of the gear part missing, the Piston is scored and worn virtically and horizontally, there is a huge gouge down the cylinder where the pin must have come out and was riding the wall (I'll come back to this in a minute), the bottom end bearing is shot,the port-job is so extensive that every edge and partitions are paper-thin and razor-sharp and to top it off the Boyseen reeds that were in it are stuck open about 1mm each so they're crap too!
I can't believe it would run! I bought a piece of crap!
Now back to the piston pin. When I took it apart I took both c-clips out myself. So if you think about it, the guy I bought it from realized the bike was not performing anymore and took it apart, found everything chewed, stuck the pin back in the piston, got another c-clip, put 'er back together and sold it to me. The bummer part is that I know him quite well and there was no mention of engine troubles. What an as#h&%e! :debil:

So. I have the bottom end in the shop getting the bottom mains done and the bottom big bearing replaced and will be rebuilding the top end Wednesday to go riding Friday. $1100.00 CAN just to get her to run right. Bummer :whiner:

I am over it mostly and am being optimistic ('cause it's all I have left - optimism) that I will have a smooth running bike that I am starting from scratch with such as a new bike.

Now, for the carb tuning........

Thanks to everyone that shared their ideas to help me along up to this point.
I'll keep you posted about how I like her now. Coming off a KX 125 years ago I was unsure if the KDX power-style would be fun enough.
:thumb:
 

m0rie

Member
Nov 18, 2002
469
0
Marsh said:
The head was flawless, BUT
both the Kips valves were in four or five pieces each with most of the gear part missing, the Piston is scored and worn virtically and horizontally, there is a huge gouge down the cylinder where the pin must have come out and was riding the wall (I'll come back to this in a minute), the bottom end bearing is shot,the port-job is so extensive that every edge and partitions are paper-thin and razor-sharp and to top it off the Boyseen reeds that were in it are stuck open about 1mm each so they're crap too!
I can't believe it would run! I bought a piece of crap!
Now back to the piston pin. When I took it apart I took both c-clips out myself. So if you think about it, the guy I bought it from realized the bike was not performing anymore and took it apart, found everything chewed, stuck the pin back in the piston, got another c-clip, put 'er back together and sold it to me. The bummer part is that I know him quite well and there was no mention of engine troubles. What an as#h&%e! :debil:

Well when its done I think you'll be happy. Just the little bit i've ridden my 89 to break it in since I did the top end (piston and rings were flat spotted and the reeds were missing pieces) has been very positive. I'd been wondering since I got it why it seemed to have wimpish low end. Always kinda thought it might have been the rev pipe i've got on it. Not so, lots more low end (must be that compression or something :)) figure with some rejetting it should rock!

-Maurice
 

rethnal

~SPONSOR~
Jul 14, 2002
659
0
I just tore mine down too and found a missing circlip.... It shouldn't effect performance as mine has 140psi compression. Off to the local indy to get a circlip and pop it back on. EG says there are only two reasons for this to happen... 1. bad installation. 2. bad rod bearing.... mine was the former. Thank Geebus! Looking for another jug for her anyway... can't have that when I go to do a topend on her in the winter....
 

Marsh

Member
Feb 26, 2004
38
0
That is labour to put in the bottom end seals, bearings and close up the cases again. I am putting the rest together tomorrow after work. This also covers all the parts, complete KIPS valves, gears,seals and gaskets. Boyseen reeds - 2-stage. New piston, rings, pin, bearing etc., rod and big end bearing, a complete gasket kit, and a brand new cylinder minus the studs.

Basically everything to rebuild the top end as if you didn't have one to start with and the labour and parts to redo the bottom end.

I'm hoping for a good break in and Friday we're going riding.

Marsh.
 

rethnal

~SPONSOR~
Jul 14, 2002
659
0
Man... after all that you will be able to fix anything on her in an evening! These things are really really easy to work on. Tore my top end down serviced the KIPS and put the circlip on the piston, put it back together, took it for a ride, tore the clutch out and massaged the KIPS rods, put it back together, took it for a ride.... I think she is coming out of it. Oh yeah... finally jetted it right too. All in a day. Can't beat that! Let us know how your bike runs this weekend.....
 

Marsh

Member
Feb 26, 2004
38
0
How do you torque down the cylinder nuts? Do you use a crow's foot? I think I may let them do these at the shop unless there is an easy way of getting in there.
 

WildBill

~SPONSOR~
Mi. Trail Riders
Mar 29, 2002
281
0
Wow! That is a lot of work. Thanks for the breakdown. I'm going to look around for a shop that can do the bottom end for me. Good luck!
 

motox

Member
May 21, 2001
90
0
Marsh, dont feel too bad. My 92 was nearly as bad.. I was an inexperienced buyer. mine needed the entire rear end replaced, bearings locked up bad, rear shock was shot etc. that was only $150, a friend mechanic did it at his house and got the parts real cheap. I had to replace the jug, it was cracked and scored. Mine too had kips valves in pieces, missing, not working. I too don't see how it was running. I paid $1100 and put about 500 in it and did all work except the rear end. It screams now, and I no its in great shape.
 

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