New to me xr400

Hello, fellow thumpers. I'm new to this site, but i have been doing a little searching.

I just bought a 2003 xr400r it seems to run fine but just not quite right. it has the gordon mods done as far as i can tell

I live at 6000' and ride from there up to 10,000' I checked the jetting and it has a 160 main and a 52 pilot i didn't check the needle setting but i assume it is on the #3 notch havn't checked the fuel mixture screw yet. It has 13/42 sprockets but the guy gave me a 14 and 15 tooth front and a 48 tooth rear.

My question is what jetting and what gearing should i be running for mountain road trail riding


Need to know more about your bike stock muffler,w/baffle or? air cleaner?  Air box lid on or off  Mods to air box?

It has the gordon free mods done according to the previous owner!

Snorkel removed, stock muffler with 4 quarter inch holes drilled, uni filter and the exhaust weld ground.

Right now it has 160 main, 52 slow jet and fuel screw out 2 turns, needle on 2 notch.

I pulled the plug today (not a easy job on the xr) and it was ash white.

From what i have researched most people say a 152 main 52 slow and needle on 2nd notch, but it seem way lean now with a 160

Thanks for the reply

My suggestion, put the 14/48 gearing on it, 152/52 jetting, leave the needle at 2nd from top. Fine tune the fuel screw for best idle and throttle response off idle. 2 turns out is just an initial setting, fine tune it from there, no more than 3 turns out.

What is making you think the 160 is lean as it is now? Don't go by a spark plug thats been installed in it for who knows how long, nor not knowing what kind of fuel was run in it. Start with a fresh plug.

I forgot to mention that was a new plug

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