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Jetting question to JD - again !!

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As per my posts last week, I've just put the bike back together with your 'base-line' suggestions. Namely;

EKN Needle #4

Main Jet #175

Pilot Jet #45

Pilot Air Jet #100

Pilot Screw @ 1.0 turn out

The airbox cover is removed, and the bike is YZ-timed (its a '99 WR with the FCR carb)

So, the results: terrible !!!

1. Starts OK, and ticks-over really sweet

2. 1/8 to 1/4 throttle, missing and banging

3. 1/4 to 1/2 throttle, really struggles to pick-up

4. Full throttle, really strong

So, what do you suggest I change first? Would I be right to guess that the bike is too rich low-down, and too lean in the middle?

Your valued help and advice would be most appreciated. That includes all you guys who have some thoughts.

Look forward to hearing from you.

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Missing and banging?

Sounds extremely bad.

Try moving the needle to #3 and recheck the needle code stamped on it. Should be OBEKN. Is there anything else you changed?

Decrease the main to a #170 also, maybe unrelated but a good idea.

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Should he be running the 65 start jet to go with the 100PAJ? Maybe lean also in the pilot jet???? I'm running a 50PJ in my bike?


What pipe are you running? Does the euro bike come with the octopuss? Have you tried opening the fuel screw?



99 WR400f, YZ timed, MX-Tech suspension, Scotts steering damper, White Bros E-Series (12 discs), tapered header and a/f. Kouba T-handle for the fuel screw. Works Connection billet throttle tube and frame guards. Cycra Pro-Bend, triple clamp mount handguards. Thumper Racing rad guards, Renthal Jimmy Button highs, YZ Tank and IMS seat, YZ number plate, odo removed, de-octopussed (Thanks Clark) EKP #4, 50PJ, 175MJ, 100PAJ and 65 SJ at 500-1000' Thanks James Dean!

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The start jet is for choke operation, should not make a difference after the choke is off.

The 48 pilot jet may be better at 1 turn out, good point.

Brett, turn out the pilot screw to 2 turns with your #45 pilot jet and retest (1 3/4- 2 1/4 range).

I am suggesting things all over the map here (pilot/screw/clip/main), but they are going in the direction of where most bikes end up.

[This message has been edited by James Dean (edited September 22, 2001).]

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Bill, there's no Octopus

JD, its definately the OBEKN Needle. For today, I'll try the #168 main as its the closest to 170 that I have at hand.

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