116 replies to this topic

[XR-rated TT Gold Member]

Happy Easter and good morning.

Yes, you should take the carb right off.  Pull the float bowl off and they're right there.

Also you may want to start a new thread or search.  These top four posts are usually just read once and then referred back too from time to time.

[chevytrkn1 TT Bronze Member]

I gordoned My 2004 xr plus dropped the front sprocket one tooth, Its like a new bike.. I would recommend everybody that has the xr do this mod as soon as you can.

[blackxr250 TT Member]

the holes do nothin for performance

[XR4Honda TT Member]

Does anyone have a picture or maybe a better description of drilling holes in the exhaust.  I have played with it a little I just want to make sure I do it right.  I have already taken the snorkel out and will be picking up the new jets for the carb tonight and would like to finish the whole thing.

[AFP520 TT Member]

I purchased new 158 Main / 58 Pilot from the dealership. I'll be installing them hopefully this weekend and I'll remove the air snorkel and muffler insert... I might consider grinding the welds on the exhaust pipe if i have time...

I'll post back with my results  

[NWxr400 TT Newbie]

So do you have a 14 or 15 tooth on the front now?   My 01, came with a 16 tooth, I sh*t canned that thing 15 tooth, but have been thinking about dropping one lower?

[Kev_XR Get Help Now]

I am running 14/45 and it works great.   Top speed is about 70mph and it works better for trails.

[RSWR450F TT Bronze Member]

I am running 15/50.

http://www.rsracing..../slides/x1.html

http://www.rsracing..../slides/x2.html

http://www.rsracing..../slides/x3.html

http://www.rsracing....slides/a20.html

http://www.rsracing....slides/a21.html

http://www.rsracing....slides/a22.html

http://www.rsracing....slides/a23.html

http://www.rsracing....slides/a25.html

http://www.rsracing....slides/a26.html

http://www.rsracing....slides/a29.html

http://www.rsracing....slides/a30.html

http://www.rsracing....slides/a31.html

http://www.rsracing....slides/a34.html

Today riding at Yamaha WR

Rosta

www.rsracing.cz

:-)

[AFP520 TT Member]

Those pics look like you had fun in the mud!!!  

I forgot to even post back here with my results...

The 158 Main/58 Pilot seem to work pretty good..

Uni Filter
Snorkel Removed
Header Welds Grinded Down
Exhaust Baffle Dremeled out Picture of removed baffle

Bike is pretty responsive to the changes... I still need to adjust the air/fuel screw a bit.. but I'm happy I can ride wheelies no problem now  

[NWxr400 TT Newbie]

AFP520,

  What is your elevation.   I have the exact same mods as you except I run 97 exhaust.  Anyway, I tried the 158/58 and my idle sucks, I tried messing with the air/fuel screw, it helped but not much.  I left my needle in the stock postion.  I think I might need to go to a 55 pilot? My elevation is roughly 2400.

thanks

[AFP520 TT Member]

NWxr400 said:

AFP520,

  What is your elevation.   I have the exact same mods as you except I run 97 exhaust.  Anyway, I tried the 158/58 and my idle sucks, I tried messing with the air/fuel screw, it helped but not much.  I left my needle in the stock postion.  I think I might need to go to a 55 pilot? My elevation is roughly 2400.

thanks

so check the idle screw dude... i left the needle alone.. only changed main/pilot and put the float bowl back on...

I'm at sea level pretty much... I posted these links for you to compare...

http://www.netstate....j_geography.htm

http://www.netstate....d_geography.htm

also reading other posts, people say they run a lower octane (91 or 89 i'd assume) to help compensate for higher elevations... 2400ft above sea level aint really that high though... you can try a 55 pilot... but i'd still say just play with your idle screw first.. then start messin with air/fuel screw  

[dirt_rider93561 TT Silver Member]

i have a 1999 XR400.  I put a FMF powerbomb header, FMF titanimu 4 muffler and put a bigger jet in it.  It ran good but i still wanted more.  So i put a white brothers 440 kit, with 10.5 to 1 compression, and a stage 2 hot cam and a new CDI.  that thing runs like a champ.  i did raise the sprocket size to a 15/49 which gave it more torque and less speed but it still runs really good. the only thing the bike needs to keep up with a 450 is a new carb.  a FCR pumper carb would just top off the rest of the bike.  that is all you need to do to your 400 to make it run good.  i can do wheelies in 1-5 easy.

[tommy06 TT Bronze Member]

links don't work anymore.. mirror?

[ixab.001 TT Newbie]

tommy06 said:

links don't work anymore.. mirror?

I noticed the broken link, too.  I think the bulk of the mods are explained in the original post to this thread.  

- lose the snorkle, put in a mouse screen
- put in an aftermarket filter (like a UNI) or mod your stock filter
- change the jetting up to 160/60 or there about, depending on extent of mods
- drill holes in the stock exhaust baffle or put on something aftermarket
- smooth out welds in the header (if you've got the time and the inclination)
- twist the throttle, honk fat wheelies, grin like an idiot
- afterward, reality-check your plug, to be sure your jetting isn't off

If anyone has the content of the original GM link saved, if you pass along whatever was there, I'd be willing to host it and put up a new link. ~ (a)

[Vegasdirtrider]

I performed Gordons mods on two of my 2001 XR 400’S and it did make a difference but I wanted more so I performed the following: XR’S Only full exhaust - 36mm Mikuni Carb, both purchased from XR’S only – I removed the air box snorkel and added a K & N airfilter and a Big Gun CDI rev box purchased from Big Gun. With these above mods, both my 2001 XR 400’S will run neck and neck with a stock 2005 CRF 450X on desert terrain.  Cost for the above mods were under $1,000.00 for each bike.
A copy of the original posting of Gordon's Mod's can be found at http://www.dirtbike.ws/node/38

[slaterg TT Member]

I really enjoy my 04 xr400 but after riding my son's 06 crf250x the 400 feels like a dog. You can only do so much. The extra 50 or 60 lbs just hurts. This summer I am going to go to the crf450x. The crf just handles like a dream, it wants to jump, it tracks, it turns, the 400 in comparison plows and wanders. Don't get me wrong I love my 400 but the technology has gotten dated.

[Vegasdirtrider]

Yes, the XR 400R has become somewhat dated and is very slow and unresponsive without the mods that I mentioned above.  However, it is a very dependable bike, it requires very little maintenance and screams with the above mods. I run Dunlop 739 Desert tires with 17 PSIG in the front and 15 PSIG in the rear. If your bike seems to plow or wander it may be caused by low air pressure or worn knobbies on you front tire. You would be very impressed with the XR 400R after making these mods.

[slaterg TT Member]

I have done the mods to my 400. Runs great, starts 1 kick hot or cold. Its the geometry. Like I said I love my 400, it takes me anywhere. The one thing I like better about my 400 is how plush it is. It is sooo comfortable to ride. Maybe I'll keep the 400 and when I want to fly jump on my son's bike.

[Vegasdirtrider]

What mods have you made to your XR 400R?

[arcangel TT Newbie]

Hi I need some help with my 400, it's a 00 xr400r got it second hand, ims 18 ltr tank 15/43 sprockets, snorkel is removed, twin air filter, pilot jet is 52, main 158, i've just repaced the piston with a wiseco 11.1 comp 87mm dia,I cleaned the head, ports and valve reseated the valves,the cam shaft i suspect is standard(can't find any marking on but it appears the auto decomp cam is removed)the welds on the header exhaust looks like it has been ground, the exhaust baffle has been removed with the spark arrester(if you unbolt the three bolt holding the stainless steel end piece there is nothing behind it) I ride at 1000m(3200ft ?) alt, temp ranges 35' c , my location is East Africa.  Now my problem is when riding a a constent speed every few moment the bike give a bit of a cough/hicup)  I can feel the bike drop in rev's and them pic up again, i suspect it is the carb(i've cleaned the carb mackin sure all holes are clean and not blocked, it ideals ok )would i have to change the jets and if so where to 60/160 any help please