KLX250 Jetting question

[farmer58za]

Hi All
I finally got my KLX250 serviced and running. The bike is stock except for a modified silencer. I'm at 5000' above sea level and the bike was jetted 100% standard (for sea level). A test run last week resulted in a heavy black soot deposit in the tailpipe. This week, I dropped the needle just one notch and most of the soot is gone but the bike still pops and farts on closed throttle. Will that be as a result of the (rich) standard main jet?
Regards
David

[Curtis]

If the carb is in good condition you should be able to run standard jetting or slightly richer.  Mine would never run properly till I binned the original carb (i tried a couple) and fitted a Mikuni VM34.

[grouty]

A great deal of the popping and banging on any four stroke is sometimes down to an air leak in the exhaust. Check the sealing of your header pipe to head and pipe to silencer (less so).
My KLX used to do this until I got around to fixing it.
Exhaust valve seat recession is also another cause. I was amazed how much my last head had worn away. I swopped the head for a good one and have been using a mix of super unleaded (98 ron) and 20% 115 ron leaded race fuel ever since. No more problem !

Glad to see it is up and running well, and looking so good.

[farmer58za]

Thanks Grouty
Put a new exhaust gasket + a smear of silicone in at the header. Some silicone at the silencer. Let's see what happens on a test ride tomorrow.

The bike is a low-miler. According to the Odometer, it's got about 3300 Miles on it. I'm hoping the valve seats are OK.

Looking inside the silencer, there's not too much soot now, but need a full throttle run to see how rich the main jet really is.


Regards
David

[cloggy]

I'm running a 30 pilot, 132.5 main and an O8 needle jet with needle on the richest setting. With a slightly different pipe I was running a 135 a 25 and a P0 [needle on leanest setting] Standard needle jet is a P2. It was way too rich with that, never ran clean.