Transition into powerband. ROUGH!

REARWHEELSLIDER · Jan 25, 2006

I took teh 91 kx250 out for a ride yesterday. I noticed the transition fron below the powerband into the band is kinda rough, sudden. Normal? Or powevalve issues? Also, If im goin down a hill, engine braking, its weary to get on the power again, it sputters, antil i give it run it through the band again. Kinda like it needs to clear its throught. (Smokes alot after the decel)

Are kx's normally this peaky?

Also, how do i get the pro cuircut pipe to mount solidly? I can hear it vibrating when im on the gas and its pretty fuggin loud. I think its loose at the cylinder. Suggestions?

THANKS
rws

FruDaddy · Jan 25, 2006

You might need to lean the bottom end, sounds to me like you're loading up at little or no throttle. Are you fouling a lot of plugs? Follow Spanky's jetting guide, it's a good run through. Ellandoh has posted it a a couple of threads recently. One of the is http://www.dirtrider.net/forums3/showthread.php?t=127204. This thing is so good, it should be a sticky.
As far as the pipe, try replacing the springs. If they are old, they may also be weak.

REARWHEELSLIDER · Jan 25, 2006

I do believe it is way rich. Hard to start. I dont foul plugs, but it does smoke more than it should when warm at idle or part throttle. Its also leavin stains on my rear fender.

Ok, another question. When the bike is rolled out of the van, cold, i kick it over. Maybe at max it will need 4 or 5 kicks, choke on, and when it does start, it revs out. Just starts screamin, then dies down to a normal idle. Normal? Should i try starting it with no choke on?

Howabout the exhaust gasket? Should it be replaced, or does it last a while/reuseable? Where can i get some springs?

Thanks
rws

REARWHEELSLIDER · Jan 25, 2006

****. Thats a damn good post. The ****in holy grail of jetting.

Thanks.

Hey, another question. Goin downhill. Ive heard from my street-two stroke buddies that its bad to let your engine decellerate you down a hill on a premixed two smoke. False, or is it really robbing the engine of lubrication?

REARWHEELSLIDER · Jan 25, 2006

Hey whats this self editing bull****? I meant to say ****!!!

benloos404 · Jan 25, 2006

the rattling from the pipe is probably the cheap exhaust gasket. On newer kx 250's they need to be replaced all of the time.

REARWHEELSLIDER · Jan 25, 2006

OK. It seems to be rattling around the cyl, so im sure its that. NOS item? It also pisses out the unburn fuel when cold all over the pipe.

rws

TimberPig · Jan 25, 2006

Sounds like your pipe o-rings and possibly the exhaust spigot on the cylinder are shot. From what I remember it is a somewhat common problem on older KX's. As to the hard midrange hit, that too is a characteristic I seem to remember hearing about with them. Cleaning up the jetting will help somewhat, but you may need to consider a flywheel weight to tone down the hit if you find it too much.

FruDaddy · Jan 25, 2006

REARWHEELSLIDER said:
Hey, another question. Goin downhill. Ive heard from my street-two stroke buddies that its bad to let your engine decellerate you down a hill on a premixed two smoke. False, or is it really robbing the engine of lubrication?

Considering that the oil is mixed with the gas, and with the throttle closed, I would say that you are depriving the engine of lubrication going down the hill. At idle the engine isn't spinning as fast. If I am coming down a long hill, I will either give it a little juice in short spurts while applying the rear brake, or I just pull in the clutch and rev it up.

REARWHEELSLIDER said:
Hey whats this self editing bull****? I meant to say ****!!!

That's just something you learn to live with on this board. The mods are really strict about the rules here.

KXtrailrider · Jan 25, 2006

I rode a 91KX for 10 years and still have it. I live at 5000ft, low end jetting was way rich for me. I think I ended up with the next leaner slide a N85E needle and a 45 pilot jet, and 155 main. To mellow the hit I used a different power valve governor spring holder that lets the power valve open sooner, it was a kawasaki part from the 91 team green report the part # is 92143-1001. I also had the best luck with carbon fiber reeds. Good luck. Ed

REARWHEELSLIDER · Jan 26, 2006

Right on. No, the hit isnt too much for me. It just seems like the motor will burble a bit when applying the throttle after its been closed for more than maybe 15 seconds. Rich i believe. I personally like wheelieing the bike upon hit!!!

rws

Transition into powerband. ROUGH!

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