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pilot jet cleaning

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Yes, you should see through the length of the jet. I let it soak in carb cleaner then blow all the holes out with compressed air.

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yeah! that's works!

had to soak it for awhile ....

then using 3/16 tubing,

put that over the screwdriver part,

then with a tapered attachment to the air nozzle

put the pressure to it .....

it took a little while, but then finally blew it clear.

It's now soaking some more ...... :thumbsup:

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I looked into getting a replacement but ......

such an animal locally isn't possible

and I had a hard time finding it online .......

heck, I don't even don't which Keihin carb i got.

i did find some pilot jets here on tt

but do i need a 21 or 22 series?

then what size?

it goes from 35 to 80, sooo ........

besides, it's sunday

I feel pretty good all in all though ....

cleared out the pilot jet

and found a broken piece of o ring

in the adjustable fuel screw, under the new one.

those little things were causing all sorts of weird problems!

now, with my bike about to be ready,

and new tires on, and new brakes later in the week ....

is my body ready for an enduro in a week?

nope ...... dang it!

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well, dang it, I still have the starting problem ....

I have to give it a shot of throttle as I crank/kick it.

can my pilot jet be clogged again?

after I just cleared it? but maybe not enough?

I have some really, really small drill bits .....

there are for making printed circuit boards ....

I got a #78 (.016") my smallest

and a few more, all bigger, but still tiny.

the largest is a #61 (.039)

btw, the 78 did not fit thru the jet hole

after I cleaned it out.

below is the carb diagram and p/ns .....

item #20 they call the "slow jet",

not a "pilot jet" like in the yamaha manual.

what's up with that anyway?

different names for the same part?

they have lots of different sizes ....

which one to choose?

I didn't see a size on my original jet .....

and what do "their" sizes mean in inches?

I figured I'd try and drill out my original

and order up a new one ...

now, what size was stock?

or what should I order?

the stocker was fine up until this problem .....

SKU: 4MX-14948-06-00

JET, SLOW (#48) AP


SKU: 4MX-14948-04-00

JET, SLOW (#42) AP


SKU: 4MX-14948-05-00

JET, SLOW (#45) AP


SKU: 4MX-14948-07-00

JET, SLOW (#50) AP


SKU: 4MX-14948-01-00

JET, SLOW (#35) AP


SKU: 4MX-14948-02-00

JET, SLOW (#38) AP


SKU: 4MX-14948-03-00




got this info here:


btw, here on the tt store there was no diagram for my bike listed ....

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its says righ tin your list 40 was standard.

I see that, thanks.

what do you think of me trying to drill it out (in my original)?

It'll be several days before a new part can be shipped in ....

what can it hurt?

I guess if a metal shaving didn't get cleaned out

and got lodged in somewhere else ...

that cold be a big pain, huh?

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do not drill the jet.

wow, I got shudders from that .....

like the voice of god thundering down on me!

I'll put the drill bits away .....

maybe I should order a spare with my replacement pilot/slow jet?

just incase .....

while I'm ordering jets,

any others I should have on hand?

I do have a jd kit already ....

god, thanks again for the advise!

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I agree, don't drill out the jet. Have you ever messed with the fuel screw? How many turns out are you? I have an '02 wr250f and was having problems with my jets getting clogged too because the bike was sitting for a long time. You should definitely pull the jet again (and all others for that matter) and clean them all thoroughly. Also, drain your gas tank into something and clean it to make sure there's no more debris. Might even want to get a small inline fuel filter. Try all that cleaning stuff and search for the proper way to set the fuel screw. My main starting problem was either clogged jets or not having the right size pilot jet. I'm at a #48 right now BTW but I ride at sealevel and in cold weather. If you do order a new pilot jet, most people run a #45.

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I now have new #40 and a #45 pilot jets. which one should i install?


(south padre island, sea level)

it's nov, temp about 60-70-80 ish

and I have a jd kit installed

i think the main is 185 .....

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install the 45

thanks, I'll give it a try ........

after my coughing stops,

I feel like i'm coughing up my lungs .....

this flu is murder!

but I think it's almost gone, i hope.

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I installed the #45 pilot jet, but I still have the same problem.

My bike won't start up properly ...

I have to give it a shot of throttle when I start/kick the bike over.

I've gone 2.5 turns out on the adjustable fuel mixture screw .......

I tried to clean out my carb, even changed out the pilot jet.

After the bike starts, it idles fine, and runs fine .....

any ideas? time to start a new thread on this?

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I have an 05 WR, I put in a bigger starter jet. I have never had a problem starting it. You should always drain the bowl when the bike is going to sit.

My pilot jet looked like yours when I left fuel in the bowl once.


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I've had to put my bike on the back burner for a bit. I'm pretty much over the flu, still have a bit of a cough etc, so I've had to get some real work done, plus some other chores, now that I can.

my plan is to re check the valves, and to do a compression check, then to clean out my carb once again.

when this problem first developed I was riding everyday, it's street legal so it's been at least puttin' around town everyday. the starting problem just happened one day. I replaced my original pilot jet from a 40 to a 45 and got the same results.

after I go thru my "plan" I'll report back ....

(have to clean out the garage a bit to work on it)

at first I was dreading taking the carb off and playing with it, now it's pretty easy and much quicker ....

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