KDXRIDER.NET

1996 KDX 200. FMF Fatty, FMF Powercore. Amsoil 60:1. New Uni air filter. 158 MJ, 48 PJ. Stock needle and clip position. My riding elevation is 400-1,000', with 700' being the average. I'm in north Texas.

Question:

1. I only acquired this bike a month or two ago and do not know when the KiPS was last cleaned. Is it possible to inspect the assembly without pulling the cylinder (I understand that I must pull the cylinder to *clean* the KiPS)? I ask because I need to jet the bike better and do not wish to start that process with a dirty/sticking power valve.

I have ridden the bike only twice since acquiring it. The first time was with the stock 160/48 jetting and an old Twin Air filter. I was running Motul 2T 800 at 40:1. I immediately discovered that I had a carb problem (would not rev up, or rev up only intermittently). Pulled the carb and discovered clogged jets and generally gummy carb internals. So I cleaned the inside with carb cleaner and unplugged the jets with fishing line. Ran MUCH better after that, but then I discovered I was getting horrible fuel mileage. I had ridden 16.4 miles that day and used almost a whole tank!

Before the next ride I ordered a 158 MJ and a new 48 pilot. I installed those and cleaned the carb again. I also installed new overflow and supply lines. Then I bought a new Uni filter and kneeded in some 10W-40 motor oil before installing it. This time I started with fresh fuel (super unleaded) and Amsoil at 60:1. The bike ran like a banshee on the top end and I couldn't be more pleased with that. But now it wouldn't idle and was quite blubbery in the mid-range. I ran exactly 23 miles (on a full tank) before I had to switch over to reserve! I refilled the tank at about 25 miles and called it a day at 29.1 miles.

2. Could part of my problem be that I didn't wring the filter out well enough before installing it?
3. I've read the threads here about the jet block o-ring and I'm about to order one, could that be the poor fuel mileage culprit?

I have not yet inspected my reeds, but plan to do so tonight or tomorrow. I *did* pull the plug today (B9ES) and noticed it was dark and wet, so I'm definitely rich (presumably on the bottom-to-mid).

I would say the bike runs too well to be worn out. Compression *feels* great, but I haven't tested it. With no load the motor revs smoothly and sounds excellent. There's no *surge* in the throttle, it just transitions from a burbling mess (that doesn't inspire confidence for, say, hill climbing), into an awesome top end that is a blast to ride. Trouble is, that transition is just too unpredictable at this point, making jumps more sketchy than they should be.

What sucks is I can't tune and ride anywhere nearby. I have to make my best guess, set it up that way, go out to the riding area (1.5 hours away) and test it. I can make some adjustments there, of course, but you don't want to waste your fee and ride time wrenching all day. So any additional suggestions would be appreciated. I'm going to replace that o-ring, check my float level, check my reeds, clean my carb, clean and re-oil my filter being sure to wring it out thoroughly this time and, if possible, inspect my power valve assembly without pulling the cylinder. Then next time I go out I'm going to check my new fuel supply line to make sure it's not leaking while riding.

4. Does that sound reasonable?


Fred B.

I'm around 500-1000 ft elevation myself. I run 40:1 lucas 2 stroke oil MJ 145 pilot 42 stock needle in the middle. You can take the plug with the flat blade slot in it out and observe if the kips shaft moves while you rev the bike. it's located on the left side right next to the kips cover. If the previous owner was running more oil in his fuel the bike may have run leaner for him, less oil in the fuel like 60:1 can make the bike run a richer fuel to air ratio. I take my air filter and wrap paper towels around it and squeeze to get the excess oil out. Wringing it might cause damage to the filter. I have ridden 30 miles on mine in a harescramble and not went on reserve, so your definetly running rich. good luck!

Awesome, thank you canamfan! I'm going to order some additional jets with that o-ring. Can I remove the Kips cover and see anything behind that while the bike is not running? I mean, general cleanliness, for example? I understand what you're saying about the slotted plug and checking the actual operation of the shaft while running. Thank you. And thanks for the paper towels tip. It's been a while since I had to do this stuff and some of it slips the mind occasionally. What year is yours?

Btw, it was definitely running rich when I acquired mine. Splooge all over the silencer and joint between silencer and pipe. The packing was pretty well soaked (I repacked it after that first ride). Not sure what fuel/oil ratio the previous owner was using, but I intend to stick with Amsoil at 60:1 myself.


Fred B.

Mine is a 99 220. The 220 uses a 33mm carb while the 200 uses a 35 mm carb, so there may be some differences in jetting there. I used to have a 200 and really liked it, the 220 has more torque but the 200 will really rev and rip. I can't remember exactly what you can see behind the kips cover but you should be able to tell if it's really gunked up. They do get pretty nasty looking, the valves I mean but as long as they operate smoothly I wouldn't take it apart.

Excellent, thanks again!

Well, the reeds looked okay but when I pulled the cylinder I found vertical scrapes/gouging of the piston on the intake side. The cylinder appears to need re-plated also. No damage at all to top of piston or combustion chamber, and con-rod has no perceptible up and down movement -- seems tight.


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Re-plate, or sleeve? Wiseco KDX 200 pistons/rings as good as OEM?

Fred B.

Looks like you also have a fracture line on the left side, good save. The piston does not look that old going by the lack of gum build up. A little suspicious about your fuel oil ratio.

One of the reasons for so much scoring could be the sharp edge on the bottom of the piston. If it's not at least 45* for 1mm you are going to be scraping the oil off the cylinder instead of forcing it between the piston and cylinder. I had two prox or oem pistons and they had 90* edges with heavy ware marks up the sides. My wossner had the 45* edge as you should. If you ever have to use a piston with 90* leading edges dress them just like transfer ports are after boring.

Personally I would only go replanted with what ever piston you like and dress it if needed.

Excellent, thank you. On the suggestion of some other riding buddies I've been attempting to use muriatic acid and Scotch Brite on the cylinder to see if it will clean up. I made a lot of progress in 30 minutes or so and here's what it looks like now...


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It appears that the cylinder scoring may just be material build-up from the piston skirt?


Fred B.

You could reuse that barrel on one condition. At the top of the rear bridges it looks like a heavy build up or the plating is worn away. It its worn away then you have no choice but to replate. I can't see any scratches above the port line so there is no reason you can't use it.
When you have cleaned it up You will have to make the decision if the cross hatching is enough to bed some new rings in. At the end of the day if your rings have a little blow by its only going to afect bottom end some.

I have a similar problem to you with heavy ware on the rear bridges. On my 200 barrel with a wossner piston every thing was ok but when I board a 200 barrel out to 220 I got heave ware on the rear bridges.
I got some advice on how to fix it but am certainly not suggesting you do the same and never on a thin cast piston.

Have a look at the bottom of page 27 as a FYI as I'm not recommending it to you.
http://www.trials.com.au/forum/viewtopi ... &start=520

Tioli, you (almost) read my mind. My old ProX piston has two small oil holes like that on the exhaust side, and it was curious to me that it didn't have corresponding holes on the intake side. I suppose the reasoning was that the exhaust side gets hotter, what with the spent gas exiting that way, but Lucky at LCS Racing proposed a similar mod to a new IT-175 Wiseco piston I had. He didn't specify the grooves that you machined in, but I'm generally surprised that more aftermarket pistons don't have oiling holes fore and aft. The ProX also has wrist pin oil holes, but I can't remember if my Wiseco did or not. I assume they probably did. As your most recent post in that thread was 12/26/2015, I assume you have not yet reassembled and tested your 220 motor, huh? Excellent write up and photos! Thanks!

Fred B.

I guess for the most part you don't need holes on the back as you have the arch and port on the back. Then if your skirt has sharp edges it's not going to help much.
What I like about the side slots is how it will lube and cool on the up and down stroke over a wide area. You can't do that on the exhaust side.

As I said my 200 barrel was fine as it was but my 200/220 barrel manifested this problem which now I have learned a new fix. I think the problem is caused by a combination of heat, skirt length, arch, chamfer, cut off. Yours is more chamfer related I think.

It's not togeather yet as I'm waiting on a new clutch basket to redo my auto clutch conversion now I know it works