steel bore and jetting

[KDXMAC]

some help here would be great,

I reciently had my 98kdx resleeved (steelsleeve). Now the guy who did the work said I will need to go up 2 sizes on the main jet, as steel sleeves run hotter than the chome standard. Ok this I have no issue with, but when I went to my local Kawsaki store they said I needed to go up 10% on the main this took me from a 160 (std) to a 175!!!...I also picked up a 170 just in case. Im not that experienced with jetting but 175-170 seems awfully rich. I have just finished running in the engine and was able to open her up and the power is great off bottom with a nice meaty middle but from then it just seems to rev, no noticable power hit. There is no surge or bogging it's smooth all the way but......im just not sure about that 175 main, I am basicly at sea level. I have noticed in other posts that most of you say the 160 is already too rich and run in the 150's. Am i just over reacting.....I didn't faul the plug and she wasn't smoking anymore than normal. Look any advise on what to look for would be great...I just whole top end done I don't want it building up with cabon due to being too rich.....sorry to babble on but im still learning the ways of jetting. Maybe I just need to enjoy the ride and stop worring!!!!

thanks
MAC

 

[Jim Crenca]

What year bike?
My 94 has a 162 and it runs great @400 above sea level with RB carb mod, pipe and silencer.
IMO, the best test is WOT plug chop is 5th or 6th gear, then cut insulator off plug and look for a 1mm band of black on porcelin.
Fishead and Acutemp have also noticed that older KDX's need bigger mains.
Check for air leaks, jet the thing right, and forget about what every body else is running is my advice.
It's best to be right on the money as far as jetting goes, but I'd rather be rich and clean the KIPS valve than fix a seized piston.

 

[andrew]

mate,
my understanding of jet sizes is that they go up in 10% increments; ie a 165 is 10% larger than a 160 and so on. I could be wrong, but that is how it was explained to me. Therefore, the advice to go up by 10% is the same as going up 1 size on the main. That was what I had to do when I sleeved my old '88 model, and that worked fine.

My advice to you would be to find out all you can about jetting ie how do do a plug reading etc, then to use your one size richer as a starting point to correctly jet for yourself.

The steel bore has a higher friction co-efficient, so it will require more lubrication than the standard bore given the same variables (altitude, fuel, riding style etc)

Good luck!

Andrew