98 kx 250...okay replated my cylinder, got a brand new keisco crank kit, keisco piston. Put the powervalve in to where the valves where open and moving like they are supposed to. now its like the bike has no power i slam on the gas and it sounds like its trying to pull the bike but its like it lacking power. run like a 125 four stroke....

did you have the carb apart? i would set everything to stock. did you do the break in?

well i didnt break anything in i never really worked on dirt bikes until i got this one as junk. and yea carb actually looked brand new clean as a whistle on the inside and out. i cleaned all the powervalve had to have someone weld the left valve cause it was broke, cleaned it all up got it nice put it all together. How would i do break in? And what actually engages the power valve slaming on the throtle or should it move at all times when the bike is running.

EDIT: ill just throw this in there, people say they can stand theirs up in 4th gear mine will not even stand up in first with the throtle slammed down from a stand still

Edited by JohnstonOctober, 16 March 2012 - 08:35 PM.

do you have the "drum" and retainer clip on the end of the powervalve rod?  take the small plastic cover off of the right side of motor and check . it's at the base of cylinder. piston in backwards? take your pipe off and see if the intake port thats on your piston is facing exhaust side(which would be backwards)

yea its all there i double checked when i was ordering parts. tomorrow ima crank it up and watch the lever when i rev it.

JohnstonOctober, on 16 March 2012 - 09:38 PM, said:

do that and let us know, my bet is on the PV not working
a bad break in wont cause this, and you havnt really had a chance to break it in. i dont want to start an opinion war on break in, but i just run the crap out of them after doing 2 heat cycles on the stand.

no power valve is working im starting to think the clutch is slipping i hear it kick in to high rpms when i turn the throttle and the lever moves out when i rev it. i dont know what wrong with the cvlutch i already filed the clutch basket smooth had some really bad grooves. clutch looked decent. my clutch right now drags a little when i have it all the way pulled and doesnt drag enough when i let go...... what to do

EDIT: Nevermind its not the clutch cause it has power till i give it more and more gas. the more i give the less power, atleast that what it seems

Edited by JohnstonOctober, 17 March 2012 - 07:12 AM.

Im starting to think that the power valve is in backwards or something, i am gonna adjust with the power valve and see how it helps. my dad is telling me the arent sealing and its causing the gas to egnite in the exhaust. when i rev it up the exhaust blows away from the cylinder...

Edited by JohnstonOctober, 17 March 2012 - 08:26 AM.

I am guessing it is the powervalve, not installed correctly. When the rod is in the valves need to seal off the side ports and the center valve all the way down and when the rod is pulled out the side valve rotate to open the side ports and the center valve raises. Kinda hard the first time but after doing it afew times it gets easier. Good luck.

Ed

give me a picture of how the sit with the rod all the way back. I am not messing with the thing until i have an explanation, i was riding it and it tried to die so i snapped the throttle and it shot up in rpm, the killswitch wouldnt kill it, so i stopped put it in first and let it go, dang thing jumped on the back tire and nearly backfliped before it died. I need an explanation of why it did that and a picture on how to fix the power valves the right way. video would be better, but i think i got it backwards when i put it in i made it close of the back holes not the sides, so just let me get a picture of the valves in place with the rod all the way back... thanks for the help yall are giving me

okay well i think i figured it out, the valves are completely closed when the main valve is closed thats when the rod is in, so now when i pull the rod all the valves open, that way it relives more gasses for the higher rpms (watched an explanation video on youtube). the reason it ran so wild at very high rpms when i had to stall it is cause it caught fire in the exhaust pipe and was igniting the fuel when i tried the killswitch. tomorrow ima try to run it. i cant tonight cause everyone in my neighborhood will call the police.

hell with the neighbors. go ride that sucker anyways. can outrun the cops if you have to

Edited by harryhandshake, 17 March 2012 - 08:01 PM.

yea... well tomorrow ill crank it i have to put water in it and everything so ill just wait. but what i said about the powervalves last post does that sound right.

anyone got a decent amount of turns i should turn the air/fuel ratio screw. with four stroke i know it 1 1/2 to 2 turns but i cant get this one right, its making it barely idle

does anyone want to buy it I am selling it, i guess dirt bikes just aint me. i have done wasted 500 dollars on a brand new crank kit, replating, piston and rings. powervalve is in right to where all valves are closed until high rpm. i cant even get it to crank now. i started it up, forgot to turn the gas on so it ran the carb dry and cut off.... now it wont start back at all, i thought it was flooded so i took the spark plug out and kit it a few good times, it still has a strong spark on the plug....... I dont understand what the issue is, it ran now it doesnt.... i tried cleaning out the carb but it was clean the jets were open float was contact........... SOMEONE PLEASE HELP....

man, if i lived closer or was on my way down, id stop in and help you out. the air/fuel should be 2 turns out from the seated position. usually if it runs better turned in, your pilot jet is to lean, vise versa going out on the screw.
you can pour a small amout of premix down the spark plug hole and see what it does. do a compression check to make sure you didn't toast the top end. i doubt it cause i have ran out of fuel on many occasions, usually out on the trail. have you repacked your silencer? a plugged silencer can make it run poorly as well or extremely loud.

Have some one help you pressure test the motor, in the FAQ pinned above is a thread on pressure testing. There is a chance you messed up a crank seal when putting it back together.

Ed

I dont know anyone who has anything to pressure check it with, but i think the pressure is fine its kinda hard to kick, makes my foot sore. I even moved the powervalves back to how they were when it did run and it would not crank. so i moved em back got it to crank for about 5 seconds then it died like it wasnt getting air or gas, tried one more good kick and it backfired... how much does repacking material cost and where can i get some. ill try that but damn this is just a pain in the ass. Spent over 600 so far and nothing. it just doesnt make sense for it to atleast run and now it wont do anything.

i dont remember how faryou tore the motor down. just the top end? this maybe opening an old door, but i have to ask. have you looked at your reeds and what condition are they in? the other question is, did you adjust your slide stop screw? i know you went threw your carb a bazillion times. i'm wondering if your slide is dropping into the bore all the way and not letting enough air to get past it. i'm just trying to eliminate things. i hate to ask, but can you post pics on your power valves installed? with the guide drums removed. just want to have a looksie. it's frustrating for sure, for you and for everyone trying to help. it's hard to figure this out over the net so please bear with us and keep positive.

Edited by bansheedave, 18 March 2012 - 01:38 PM.

yea, i am trying but the powervalves i would take pictures but i dont have a camera good enough to show anything up close like that. I can try to explain how i have them in. With the rod all the way in like it would be on idle the main valve in the center of the exhaust is up like everyone tells me it is supposed to be. both of the side valves have it so the slits are facing towards the exhaust pipe but wont let any air get from the cylinder. when the rod is pulled out the main valve drops down, and the side valves open all the way to where they line up with the hole going back into the cylinder. Now the reed valves last i checked they looked fine i havent messed with em since i had the cylinder replated, it ran just yesterday why would it not run today. i will mention i put 97 instead of 87 gas in it and mixed it 40:1 to a gallon. I thought it would have been that cause it hasnt ran sense so i drain the carb and the tank and put fresh 87 mixed with the same ratio. Like i said though the engine has been torn apart from bottom to top and everything has been checked out, got a new crank kit, with crank seals top end bearings and all that, cylinder has been replated, and got a new piston to finish all that. I have rode it sense i done all that, but it did not have any power, and when i was riding it, it tried to die so i snapped the throttle and it shot up in rpm and would not die with the kill switch, and i had to jump off the clutch for it to stall. (I think the powervalve stuck open cause it was a little hard to turn) it has crunk sense then but didnt make it but around my small yard 3 or 4 times. once i got home from riding it when the rpm incedent happened, i tore apart the top end and it all looked fine, re adjusted my power valves cause i thought they were wrong, turn out they were right, so i had to adjust em again. I cleaned em realy realy good oiled em got the moving smoothly and it hasnt crunk since. I have been working on this thing longer than i have ever worked on anything in my life. its just getting so irritating. tried to bump start it and its like its not firing but the spark plug shock the crap out of me, it has a strong spark....