Gordon Mods......02 XR 250

As I am very new to the sport, and also very new to working on bikes or performing modifications of any type, I am wondering what order I should do the modifications, and also, while all you TT experts are responding, would like to know which of the mods are a bit more difficult to do than the others. I know drilling the hole's at the muffler's end is likely the easiest, but rejetting is a bit intemidating as I really don't want to screw up a perfectly running bike. If i do some mods to the exhaust does that force my hand in having to do a rejet. I look forward to digging into these things, just apprehensive to get into it.

newbie jokes accepted and expected. thanks in advance.


Once removed, if you modify your baffle as shown in the picture the power difference is very noticeable with only slightly more noise. It's just a matter of grinding off the welds holding the small pipe into the back of the baffle. I did not have to rejet after this modification but when I opened the airbox and ground the header weld I did then have to jet up. I'm at about sea level. I found the bike to be too loud for my taste with the baffle completely removed. Maybe someday I'll make a down-turn for the exhaust and pull the baffle again.

Rejetting the XR is easy. The mainjet can be changed without removing the carb, or even the float bowl. The mixture screw can also be reached easily with a small screwdriver.

I have the baffle removed as well as the backfire screen on the OEM air filter cage, and I've had good results with a 135 main and 2.5 turns on the screw. I'm typically 200-700 ft above sea level.


eeeeeeeeewwwwwwwwwwwwwwwwwww, that's gross.

Please don't point that thing at me! :cry:

JazzBrother- I fixed my picture and I also fixed yours :cry: Sorry about the picture but it was my first attempt at puting a picture up on this site. I'll try to do better next time. About the baffle- All I can say is try it. The original inside diameter of the small pipe was .378". The new opening is .525". I'm not sure if all of the gain is from the diameter of the baffle or if it has to do with the area behind the baffle allowing a less restricted flow. The noise level is higher than stock but no where near completely uncorked. I also noticed a loss of bottom end with the exhaust completely uncorked as compared to running the modified baffle (jetting and carb adjustment set for both). Just try it or not. Then you'll know what I'm talking about. Also, could one of you math wizzes figure the flow difference based on the numbers I supplied.

Thanks for the input guys. I'm glad I asked before digging into some changes that were not needed.

I have two '04 XR250's (and I'm glad i bought the second one since there are no new ones coming out). I took both bikes up to the trail yesterday and tried out the new one without any mods compared to the older one with most of the mods done except the sparkplug resistor. Obviously there was a very noticable difference, especially with long hill climbs. Then I removed the airbox snorkle and saw a moderate improvement. After that I took out the baffle which is very easily done with a torx screwdriver and a regular screwdriver to gently pry it out. Huge difference!! I could now climb any hill in the area either lugging slowly up the gnarly ones or accelerating up the easier ones. There may be a slight difference with the other bike which also has the header welds groung and the Uni filter - but not much.

The bike comes stock way too rich for Colorado. After the mods it's still too rich but better than before. I'll be dropping down to maybe a 125 main jet for my rides which are mainly 8000 - 11000'

As others have stated...your biggest gain will be gotten by removing the baffle. The other mods, by themselves, are minimal gains. But if you do all the others at once, you will feel moderate to significant gains over the baffle removal alone.

Good luck! :cry:

i tried to remove my baffle and when i tried to pry it out with a screw driver it just bent the lip on the baffle. what do i do now?

i tried to remove my baffle and when i tried to pry it out with a screw driver it just bent the lip on the baffle. what do i do now?
I made a hook for my slide hammer that went all the way inside the baffle and hooked the back edge.

You can also use two wide blade screw drivers, one on each side to carefully pry it out.

Hi there, I’m a newbe in the Motorcycle business and I just want to ask if my xr250r 2004 has a removal baffle, I read in another thread that are two types of baffles one that cannot be quit and other that can be removed, how I know if mine can be removed? and other question I drive in 3280 feet, how can I know if the motrocycle is rich.

Thanks in advance. :applause:

There's an excellent thread on this topic by MAR...here's the link


If the link doesn't work you can find it in this forum as a sticky, "Helpful for the New XR owner"

This has almost all the info you'll need about uncorking your stock pipe :p

I had the same issue with my 96 250R...the pipe is sealed shut and totally different to the american model A1 and A2 pipes cos i got my bike from Japan :p

I decided to go for a Supertrapp disc type pipe cos it's easier to tune and has a more throathier tone than the stock :lol:

About your other problem with the carby... Spark plug seems to be the best indicator to judge a possible lean or rich fuel condition.

If it's whitish gray kinda colored....you're too lean

If it's sooty and dark with carbon deposits...It's too rich plus many other horrible things :p

If it's tan brown kinda color...you're all right :applause:

By the way...i learnt most of this stuff by reading earlier threads on this site so i'm sure our senior TT'ers will be able to help you more :p

Good luck with your project and glad you chose an XR :ride:

Thanks for all the advices, I will read the thread that you sent and try to check de spark for the rich status, Im not so shure but my motrcycle appears to be a japan model , I will check as soon as I can to ensure I can remove the pipe :applause:

Gordon mods are easy and worth it...you can change jets in 15-20 minutes, just rotate the carb about 45 degrees.......good luck.

can't seem to access your pics...

I think the most important removal is the wire mesh screen in the airbox and installing a high flow filter and removing the top of the airbox (snorkle - baffle) I went to a 135 main jet and a FMF Q2 pipe. My initial impression upon riding my new 04 XR250R "uncorked" was that this could not be the same bike, strong wicked quick pull, wheelies at the twist of the grip in second and sometimes in 3rd (slight uphil gradient). Today I am going to install a 48 pilot to cure the cold start and hot restart problem.

Hi I have just installed a 135 main jet in my bike goes well, is it worth putting in the 48 pilot jet, I don't have any problems starting. the only times I have problems starting is if I stall on a hill or lay it over than I have to kick until it clears out. I have removed the wire mesh screen in the airbox and installed a high flow filter and installed another pipe, bike goes well. I only have intake valve recession problems I have to adjust every 60 miles

Any mods for my bike much appreciated I have a Honda XR250R 2004 model

regards Sam

, . I only have intake valve recession problems I have to adjust every 60 miles

This is an indication that the intake valves should be replaced soon. I have removed intake valves from XR250s that were worn so badly that the edge of the valve was sharp as a knife blade. When the edges of the valves get that thin, they can easily break apart causing major damage. Kibblewhite valves will cure the problem.

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