1990/91 KX250 Rear shock

[1989kawasaki]

when i first got my bike i was afraid to change the water pump seal. well the way i did it was : make a clean and open work area , keep track of every bolt (all the bolts were the same but i didnt know at that time) , remember how things go back, and being very careful with the delicate parts . and TAKE YOUR SWEET TIME DOING IT. that cant be stressed enough , if you rush you are bound to lose something or break something.

[stevea100m]

I run a 32:1 mix using yamalube-r. Once you get the bike running with a fresh piston, put a brand new plug in it and run it around a field and no higher than quarter throttle till its nice and hot then I'd check the plug color. If its black you need to change the pilot to a smaller pilot jet. if its white you need to go bigger but seeing as how theres a ton of ash on the top of that piston i would say your gonna downsize it. One thing I can tell you is that these kx250s are jetted rich from the factory and if no one has ever changed the jetting then it deffinatly needs to be changed.

[elmo]

Thanks for all the help here guys and i'll keep you lot updated!

[elmo]

Righ guys gonna sort out my jetting as you lot say its well out due to the carbon on the piston and the fact it fouls plugs pretty much all the time.

So i understand to do this i need to, decrease the size of my needle and adjust the air screw...

My question is, what size needle and how many turns on the air screw. Im only about 150m above sea level (so i'm basically a fish), in England.

[Caddy 16v]

Hi,

could you write down the size of your main jet, pilot jet and what needle and on what clip it is from above?  There could be something completely different in there from stock, or way off! I'm about the same elevation as you in British Columbia.

You could start with the needle on the 3rd clip from above and the air screw 1.5 turns out.

I run a FMF Gold Series pipe and a stock silencer, my needle (R1638J) is on the 2nd clip from above and the main jet is a 165, air screw 1.5 turns out, haven't checked the pilot jet, yet.

Stock at cheapcycleparts.com it says: Needle N85C, main jet 160, pilot jet ranges from 52 to 62.

Hope that helps...

[stevea100m]

To give you an idea im running a 45 pilot 160 main at 750ft. Not sure on the needle. I would start by changing the pilot first though

[elmo]

Thank you guys great help! i took the cylinder off today, Whats the best way to clean the cylinder btw guys?




And the bolts for the exhaust valve i didnt even realise wser bolts


Piston


And this is one of the reason the powervaves wernt opening!


And 1989kawasaki thanks for the heads up on bolt storage lol


i'll take the carb apart tomorrow and post the numbers on here...

Thanks again guys

[1989kawasaki]

  i think the cyl needs replating , its hard too tell with all that black stuff there.
when you send the cylinder to a plater they will make the it look brand new
now to clean the power valves and that rod, i think you have to use oven cleaner and a scrubber.
A+ on the bolt storage , you will never lose a bolt that way 

estimated cost = $500 - 600 and that includes a new piston kit

[elmo]

Right ok so the needle say's N85C and the clip is on the 3rd ring back and the air screw was 1 turn out!

ps... pilot says 55 on it!

[Caddy 16v]

Take the drain plug out of the carburetor bowl and check what size the main jet is as well! But so far it looks stock.

[elmo]

Main jet 160

[stevea100m]

i would drop that pilot down quite a bit to about a 50. One thing that I can tell you is if the cylinder needs re-plating your going to want to send a brand new piston with it.

[elmo]

cheers guys, i have a new piston.... so your saying send the new piston with the battered cylinder for replating? i imagine its so they can check the bore afterwards....

i'll order a new pilot jet later too.... cheers again guys

[stevea100m]

Yes send it with the cylinder. They use it to check the measurement and clearances before and after the job. One thing I would do though is dont jet the bike till after you have the motor broke in. Once its broke in then start jetting the bike

[elmo]

ok so found a new part to order.... and the main reason the KIPS wernt working!!


as you can see the pin has managed to snapp off and fall into the valve! Lucky i decided to pull the engine apart!