Xr400r jetting

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James 00
Posts: 4
Joined: Mar 01, 2017
Location: Olympia Washington
Rides: Dirt bikes
Vehicles: 2000 xr400r...2006 honda crf150r

Xr400r jetting

Postby James 00 » Thu Mar 02, 2017 9:59 am

Hey I have an 2000 xr400r and I have done all the Gordon's mods to my bike but the jetting is way way to rich. I live western Washington and run from 500 to 3500ft... everything is stock except the Gordon's mods..air filter is an Uni. Needle in the 3Rd grove also. Ive tried going up on jets sizes on both jets Wich made it way to rich the plug was BLACK. I went up 1 size on the slow jet(from stock) I had a hard time starting and running without popping. The fuel screw I could close all the way and the bike would not die!!! So back to stock jets. At stock the screw is out 2 turns and starts fine...... any ideas on why my bike won't except the jetting changes like all the other bikes I read about. They run higher altitudes and higher jets sizes with stock like me?

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4Strokes
Site Admin
Posts: 1233
Joined: May 02, 2016

Re: Xr400r jetting

Postby 4Strokes » Thu Mar 02, 2017 1:08 pm

Hello and welcome. If the jetting is way too rich and the spark plug is black, you would want to reduce jet sizes, not increase. First of all, what is the bike doing that is a problem?

James 00
Posts: 4
Joined: Mar 01, 2017
Location: Olympia Washington
Rides: Dirt bikes
Vehicles: 2000 xr400r...2006 honda crf150r

Re: Xr400r jetting

Postby James 00 » Fri Mar 03, 2017 10:10 am

I did the Gordon's mods to it to get a little more grunt down low... it runs fine with stock jets in it now but curious why my jets stayed same and everyone else's when way up in size and my altitude is lower then most

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4Strokes
Site Admin
Posts: 1233
Joined: May 02, 2016

Re: Xr400r jetting

Postby 4Strokes » Sat Mar 04, 2017 2:37 pm

It's hard to tell why without knowing exactly what was done with the uncorking. I know the XR came slightly rich from the factory so that might have something to do with it. Did you leave in the stock restrictive air filter?

James 00
Posts: 4
Joined: Mar 01, 2017
Location: Olympia Washington
Rides: Dirt bikes
Vehicles: 2000 xr400r...2006 honda crf150r

Re: Xr400r jetting

Postby James 00 » Mon Mar 06, 2017 2:45 pm

I put an uni filter in ground down the welds on the header pipes opened up air box and drilled holes in the stock spark arrestor.


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