KDX 250 1992 Fork Oil Questions

[Matt90GT]

I need to know the level or amount of fluid to add. Also the weight.

I am 175lbs, ride aggressively. I was using 10W oil in my xr600, but that is a bit heavier beast. we also run that in a friends kdx200, non cartridge fork with great results.

Also is there any adjustments to the 1992 Forks? rebound or compression?

Thanks!

 

[jmutiger]

The 250's forks are Compression adj. only. I have the same bike, and I just go to Race Tech's web site, and use their "computer" to remind me of how much oil to add to the forks. I always forget.

ps. Maxima Racing oils makes some of the best quality fork oil you can beg, borrow or steal, let alone buy.

Jon!

 

[Matt90GT]

I have been running the amsoil and have been happy with that. I get it at dealer price having a membership for it.

Looked there on the ractech site. Says " see instructions" and under the weight just list 2 quarts.

Any more help would be appreciated.

 

[dirt bike dave]

Matt - 5w - 7w should be fine. Heavier weights will increase the rebound damping.

Check your stock oil level with springs out and forks compressed. From the top of the fork tube, it will probably be about 5". Raising the oil level to about 4" - 4.5" will provide increased bottoming resistance and stiffen the last few inches of travel, which is nice if you are running the stock (soft) springs.

IMO, stiffening the fork springs and revalving the stock forks to have less high speed compression damping makes a huge improvement on the KDX 250 for trail riding.

The 250 is one bike that really benefits from a proper set up, as Kawi did not do a great job on the jetting and forks.

 

[Matt90GT]

Thanks dave!

Would a .45kg spring to stiff? The reason I ask is because I have one in my xr600 and could swap it out before selling it. But I think that it may be a bit to stiff since this is a lighter bike.

Any tips on jetting? I am probably going to tear into the carb tomorrow.

The bike supposidely has a ported/milled/polished head. FMF pipe with FMF turbine coreII SA. I am installing new FMF torque reeds and a PK vent kit.

What is stock? I guess if I know that I can figure it out from there.

I am getting a manual here soon! Thanks for all the help.

 

[Oregon Trail]

Matt, I'm running .43 Eibach springs with 5w oil set at 120mm and I weigh 225lbs. I put 10w in once and after the ride went back to 5w. I didn't like the feel with the 10w.

 

[dirt bike dave]

Matt - I sold mine a couple of years ago, so I don't remember all the jetting specs. However, my buddy and I did manage to get ours jetted well for use at about 4,000 feet elevation by leaning out the stock settings considerably.

I think we used the leanest pilot jet available from Kawasaki (#38?), went down one or two sizes on the main jet (#158? or 160?), used a KX slide with 1mm more cutaway (or you can modify your stocker). Used a thinner head gasket from an '88 KX250, FMF pipe w/modified aftermarket KDX200 silencer, Boyesen reeds and rad valve, and opened up the side KIPS valves w/a dremel tool so that they were flush with the floor of the exhaust port when fully opened.

The end result is a very good trail engine with excellent low end (the stock flywheel is VERY heavy), smooth power delivery and a decent top end. Mileage is very good as you run down low in the powerband.

Other little tricks on this bike are to cut down the front of the seat foam to improve the riding position, shave the steering stop down so that the bars can turn further, raise the forks so about 3/8" are above the top triple clamp. If you run tight woods, you can shorten the chain and move the rear wheel all the way forward to shorten the wheelbase.

Use a good front tire like a Michelin S12 and a steering damper is always nice.

The stock forks are grim for the woods, IMO. My springs were 0.41 or 0.42, can't remember. Used Race Tech Gold valves, but with much less high speed compression and slightly more low speed compression than the RT charts showed. Ran the front springs with no preload so that the front would dive slightly when cornering (the stock steering is slow). Very plush in the rocks but much better at speed than the stockers.

Super stiff springs with the stock fork valving would not be good on rocks and roots.

Hope this helps - enjoy the bike. Mine was very reliable and lots of fun.

These changes helped the bike greatly for woodsriding and I honestly preferred it to my'90 200.

 

[Matt90GT]

Thanks everyone for the replies!

I have a dunlop 752f on the front, brand new. The rear is also a dunlop I believe but a 19" wheel and tire. I am still anxoius to ride the bike but I am going through it from top to bottom at the moment.

I am going 5w oil in the forks also. Start there with a 4.5" from the top. Does anyone know how many CCs that is by chance? I am being lazy

Thanks everyone!