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Jetting Settings

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The blue needle is for cold temp!You should be using the red in the #5 from top and 172 with cage or 180 with out :cry:

So does 40s and 50s count as cold temperature? Went riding yesterday and temp was upper 40s with my above posted settings. Bike was a major paing to start but once started, it screamed! BUT, it also started bogging on hard landings.

I want to try your suggestion here but I think 180 might be really rich. The confusing thing is that James Deam told me to go 170 with the red needle or even lower.

Why does jetting have to be such a PITA. :cry:

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The blue needle is for below 50F and will richen the lower throttle range.Also you would want to go one size larger on main.You said Florida so i figured 60F or better?If you have removed the backfire screen yes [175-180] main...My bike ran good at the last southwick 42F that day!!!Red 4th from top 175 main fue screw 2.5 turns out no screen. :cry::cry::cry:

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Thanks cjlan66,

I think I've tried those settings before and liked them but my bog was absolutely terrible so I wnet with the blue needle which seemed to have taken care of most of the problem. I seem to remember tho that my bike ripped much harder once out of the bog region.

I just ordered a #55 Leak Jet so when it comes in, I'll go back to your suggestions and give it a shot. :cry:

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Try to turn the fuel screw in or out and make sure the bike is idle a tad higher then you would normaly set it [1700rpm].This fixed my low end bog!!! When i rode 2stroke i set the idle so the bike would almost stall. When i went 4stroke that gave me a low end bog!!

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04 CRF250X CA Model

Airbox cut to factory specs

Exhaust baffle tube cut off

150 Main

42 Pilot

Stock Needle 3rd clip

Air screw 2 turns

14/53 Gearing

Went for a ride at Gorman on Christmas Day. Wow! What a difference. Pulls the front up in second like it should but needs a 6th gear. Bought a 51 rear that I hope to put on this weekend.

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I just put the JD kit in and white bros e2 pipe, air box cut, pink wire mod,zip ty fuel screw, stock gearing for now the bike rips now. I rode in the red mountian area this weekend and no bog, the wheel comes when i wanted it to unlike before but lt needs more top end. Jet kit done per directions for 3000 elev. and warm temp.

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JD shamdy,

That guy's not the fix all....... Ther's Way more to it than just needles.....get informed..

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I was just posting the difference I noticed after I put the jet kit in and it indeed made a huge difference from stock.

So inform us.....:cry:

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Do you have to pull the carb off to replace the leak jet or will turning the carb to one side be enough?

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Hello

Just bought an '05 CRF250X. Rode it pretty hard yesterday for the first time after 'break-in'. Noticed that the stock jetting is a little on the lean side.

Has anyone had success with stock needle and air screw adjustments?

I've read most of this thread and am left a little confused due to the extreme range of main-jet and needle's, etc, being used. Along with some major modifications that I seriously doubt I'll ever use...

I'm really just wanting to tweak what I've got. I ride in North Alabama mostly, which is around 600'-900' altitude.

I am curious about air box mods and exhaust mods to the stock equipment. Is there a forum or quick guide for these mods? I underatand that I should wait to mess with the jetting until ( if ) I decide to modify a few things.

Any help would be greatly appreciated. Thanks!

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Go to Rick Ramsey site he has a lot of useful info. If you do the air box & exhaust mods you will defentily have to rejet the bike.These bikes come way lean from honda after I jetted and put on a pipe and and some of the ccc mods the bike runs very good, no bog no problems. :)

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hi for your R a #42 pilot works good main jets can verie personally i'm running the biggest one honda give with the bike when new the size i can't remember but if you check out the bills exhaust web site they have a good guide to start with.

:)

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I finally finished my little jetting project. Well, I say "little" but actually the project was huge pain. The CRF250X is a difficult bike to work on. However, the reward was good.

Like I mentioned in my first post I felt the 250X was jetted a little lean. Maybe more than a little. Jetted lean enough stock that the engine knocked. Not a good thing...

Anyway, I installed a 140 main, 42 pilot, and went two more notches on the stock needle. I also installed the Zip Ty fuel screw. You'll pretty much have to purchase one of these. There are several companies the make em, but the Zip Ty has numbers on them that well make the jetting job a little easier. Fuel Screw

In addition, I opened up the airbox. Not to the full CCC specs but I cut as far back as the battery. Under the battery I drilled two 3/4" holes. I also used the same drill bit and drilled a hole in the back of the baffle. This frees up the exhaust and still keeps the 250X quite. Oh, and I took out the backfire screen. One has to wonder how a motorcycle can breath through that thing. It's history!

I used the the engine rpm method to set the fuel screw. This is kind of a test to see if your choices in main jet vs how much you opened your bikes breathing were correct. I got lucky. Although I did A LOT of research before I decided anything. I achieved max rpm at two turns out on the air screw...thank god. It was hard work and I didn't want to have to do it again.

If you get passed three turns you probably need a lager main jet. Which means starting all over...bummer.

Did it make a difference? Yes, but not a hell of a lot. But with a 250cc 4-stroke every little bit counts. It IS stronger off the bottom and pulls longer harder. I detect no bog off the throttle which is now VERY responsive. One of my main concerns was gone...the engine knocking. There is only your basic engine noise now.

I tried to not get too carried away. If I wanted to turn my 250X into a 250R I would have of course bought a 250R.

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Hey Ladys & Gents!

Just hooked up on this great site...

This info may help some, general info from Honda Australia! (Note STD U Type may be different than US, ED Type ETC) Still very good base settings! :)

When playing with mods & exhausts it's very important to run these little babys on a nice mixture, they don't like being LEAN...

CRF 250X Competition Settings

This information is meant as a guide only. Jetting may need to be changed to suit extreme conditions

In standard trim as delivered the CRF produces approximately 21 HP.

With a full race exhaust system fitted, airbox opened up and rejetted the HP goes up to around 31HP.(stage 3 including ECU mod)

Stage 1

CRF 250X with Header and Exhaust restrictors removed (note no airbox

modifications)

Replace Main jet with a 142. (Standard 130)

Pilot 42 (standard 40)

Needle and clip position NCVT #3 (this is standard setting)

Air screw 1.5 turns (std 2.25 turns)

Summary: Remove exhaust restrictors, replace main jet with a 142 and turn the

Mixture screw to one and a half turns.

Stage 2

CRF 250X with race spec silencer and headers fitted .(note no airbox

modifications)

Replace Main jet with a 152. (Standard 130)

Pilot 42 (std 40)

Needle and clip position NCVT #3 (this is standard setting)

Air screw 1.5 turns (std.2.25 turns)

Summary: Remove original exhaust and replace with complete Race Specification

System. Replace main jet with a 152 and turn the mixture screw to one and a

half turns.

Stage 3

CRF 250X with Complete Racing Specification Exhaust fitted. Plus Top of

airbox removed on moulded line.

Replace Main jet with a 160 (Standard 130)

Pilot 42 (standard 40)

Needle and clip position NCUT #3 (this is standard setting)

Air screw 1.5 turns (std 2.25 turns)

Summary: Remove original exhaust, replace with complete Race specification Exhaust system. Replace main jet with a 160 and turn the mixture screw to one and a half turns. Remove the top of the airbox. There is a line moulded into the top of the airbox. Cut along this line.

Change the ECU wiring harness as per the CRF 250X bulletin.

Behind the left side cover there is a "natural" colour main coupler .On the ECU side of this is a Pink

wire. Underneath the pink wire is a blank terminal plugged with a rubber

cap. Swap the positions of the Pink wire and rubber cap. Reconnect the

coupler to the wiring harness.(in modified form ,the Pink wire is not connected to any other wire.)

Hope this is ok!

Regards..

REDWINGBLING

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Ok, here's an '04 CRF250R, OEM air filter, backfire screen REMOVED, Dr. D full exhaust, JD jet kit installed.

175 main

42 pilot

red needle

4th clip from top

1 1/8 fuel screw

55 leak

Running at 3000 feet (900 meters) in the summer from 55 to 75 degrees F (15 to 25 C).

Chris.

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04 CRF250X CA Model

Airbox mod

Backfire screen removed

Stock Exhaust

JD Kit

42 Pilot

158 Main

Zip Ty screw out 2.25

Red marked needle clip position 5

Had a definite bog off idle before, that is completely gone and replaced by a nice hit. What a difference! And such an easy fix. I just got the bike and it only has 23 miles on it and I'm very pleased with the new jetting. :)

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