new carb ? jets

[CJquaddad]

Putting PWK28mm carb on ported hi compression 90 what would be a good starting point.

[wrhracing]

Sea level/high humidity/hot weather/C-12/45 to1 semi synthetic or synthetic/advanced timing.

42.5 pilot/needle in the 3rd 4th or 5th clip position/145 to 165 main.

To many needles to chose from and the needle in a Keihin or knockoff D slide greatly affects the mid to top because of the many possible lengths and different tapers.

[CJquaddad]

Thanks that is what I was looking for. Just somthing to try before I get started on it. I had a 24mm PE on it with a 55 and 155 in it with the needle on the 3 from top . I"m 900ft how much diffence would that make. It does have advaced timing and C12 is what I use with Klotz oil. Thanks for info. Imay get to work on it tonight.

[dericsdad]

We are at about 1000 feet, 75-90 deg. and mostly humid weather. We have a 28mm keihin, and run a 42mm pilot, 4th clip position down, with a 155 main. It is a 2005 kawi kx85 dirtbike carb, so i'm not sure what the needle size is. We run 110 octane turbo blue with 48:1 Amsoil Dominator.

Billy, where can I find a 42.5 pilot??? I think it wcould help ours, it could be just a tad lean at 1/4 to 1/2 throttle yet.

[wrhracing]

I believe the air temp and humidity difference would be a larger factor. Colder the air the more fuel the engine requires.
I'd start at 42.5 pilot , middle clip, 135 ..
Then just run it to make sure the middle is clean. Stressing that now is not the time to check and see how fast it will go, just check that it accelerates cleanly when you whip open the throttle under a load.
Bring it back for a plug check.
If it took that middle position on the needle then go one more richer, then test run it again. If it takes that clip change do it again until you notice the engine starting to run poorly. When it runs poorly. Then go back one clip position leaner and run it to verify the engine runs clean again.
By this time you will have plenty of color or lack of color on your plug. If there is any white or orange or green on the plug then go up 20 points on the main jet. If it doesn't take the 20 points without running poorly. Then take 7.5 points away from the main JET. and try it again. etc.etc.
However if it does take the 20 points then you need to continue going up on the main at least 10 points at a time until the engine gurgles ,chokes , runs poorly etc. Then drop the main 7.5 points and you will be jetted properly.
When jetting for the main, these are wide open runs so if you ever feel the engine nosing over (Running out of fuel) you should get out of the throttle and nurse the bike back let it cool off and install a bigger main.
JRemember, just because your tired doesn't mean your thru.
Good Luck!

[wrhracing]

Originally posted by dericsdad
We are at about 1000 feet, 75-90 deg. and mostly humid weather. We have a 28mm keihin, and run a 42mm pilot, 4th clip position down, with a 155 main. It is a 2005 kawi kx85 dirtbike carb, so i'm not sure what the needle size is. We run 110 octane turbo blue with 48:1 Amsoil Dominator.

Billy, where can I find a 42.5 pilot??? I think it wcould help ours, it could be just a tad lean at 1/4 to 1/2 throttle yet.

Sudco in California is where I purchase most of my jets. They will sell to individuals at retail pricing.
There is also a place called Carb Parts warehouse.
if they can't help ya, you could more than likely track me down and I can check to see how many I have.
I think the KX Carb is slightly different than the oko carbs, in the slide area. But none the less a great performing carb.