1990/91 KX250 Rear shock

[elmo]

  New problem.... The tensioners in the swing arm SNAPPED Fuc@$%?$^?"^$"$%"&$%""%&^%&"

Tried getting them drilled out and the holes tapped... ALL of the drill bits have blunted or snapped even really high grade ones...

WTF am i going to do now?

[elmo]

found a second hand one, ?80 bastard! Just gotta wait for both last parts to arrive now

[elmo]

Right guys Good News!! After all my hard work she looka a dream! Kicks first time everytime too!

This is how she looks now! Everything as tight as a new bike (except engine as i hadnt touched that)







So i took her out for a track day to test out the new beauty! Low and behold Bad news always follows good..



First she wouldnt hit powervalves in 1st 2nd or 3rd... Then she soiled a spark plug....Still had a good few hours on her.... Lively, suprising hours as the powervalves sometimes kick in, could be anytime but always very late.... Making the back wheel very skittish all funn aside i need to fix this before i take her out again... Any ideas anyone? anyone had this? I'm gonna try taking the valves out and cleaning them incase they carboned up... Other than that i'm lost... Do these bikes have cable operated powervavles?

[elmo]

Ok so started tearing into it today, ordered new piston and top end gaskets along with a workshop manual... hopefully i'll just get away with a top end rebuild for now and it will sort out the missing power..


She's pretty black and got a nasty wobble back and forth


Powervalve's also look ok thats them nearly open, and the piston a little scratched



Powervalve pulley?!?!?


But i have already cleaned the head ready to go, soon as my piston, rings and little end bearing get here (with the manual!)


Now do i try an clean up all this black s**t? and the oily black s**t? and what do i clean it with?

Cheers guys

[1989kawasaki]

Holy crap!  what happened? what mixture were you running? once you get the new top end on make sure you mix at 40:1 and get the carb jetted! and it will never look like that again.
on my rm250 that runs 40:1 with amsoil interceptor, well i looked into the cylinder and it is SPOTLESS not even a single carbon black mark! which was unbelievable  to me

[stevea100m]

If the piston is wobbling in the barrel then i would look into having the cylinder re plated. It could be the bore is worn out. Looking at the top of the piston it looks like if your running 32:1 that you need to jet the bike badly as there is too much carbon on the top of that pistons

[elmo]

Lol... I am still really new to this.. but I only bought this bike on the 31st of March!

Cheers for the heads up on the mix, i'll make sure I do that.. So I take it the black marks are not good?

The head and cylinder look in ok condition to me, but i'll know more once I take her top off. But i'm gonna wait till the manual gets here so I dont pull anything out wrong... specially that powervalve setup!

I was just using a standard 32:1 (156ml to 5 litre petrol)

Sorry guys whats jetting?

[1989kawasaki]

No elmo, (LOL) the blackness should not be there.
you are going to have one hell of a scrubbing job to get everything clean! especially the power valves
 and the exhaust port.

[1989kawasaki]

oh yeah and 40:1 is 500ml to 20 liters of fuel.

[1989kawasaki]

did you hear any piston slap when the bike was running?
my 89 kx250 had bad piston slap a LONG time ago.

here is an old video of it. at around 12 seconds you will hear the slapping

http://www.youtube.com/watch?v=XE9u6l7onmQ

[elmo]

is that the noise where it sounds like its dying out?

if so then yes.... lol i thought that was just normal....  that was more than likely why i couldnt get her to idle!

[1989kawasaki]

is that the noise where it sounds like its dying out?

its when the sound clearly changes at around 12 seconds

[elmo]

wow i really have lots to learn lool, thanks guys so much... i know everyones prob pissing themselves reading this!!

[1989kawasaki]

wow i really have lots to learn lool, thanks guys so much... i know everyones prob pissing themselves reading this!!

hahahaaha its perfectly ok to be ''slow'' at first. but it will get better

[elmo]

:-/ I hope so... at least i'm eager! I have another few mates that recently started, they all bought bikes too... their bikes are in worse condition than this! They are both too scared to touch anything to do with it too.. I cant wait to bring this back out and show them what a real bike should feel like.. But from what you say i'm prob better off pulling the bottom end apart too an checking everything down there for wear too!

Also i take it jetting is done to the carb? What does that involve "specialist work"? And replating i understand what that is i'll just look into where i can get it done and prices.

Is it going to be nessacary? the piston can move in all directions about 1 to 2 mm.. i take it that is also not normal