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Hard to start 02 YZ-250F

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Just got some great advice the other night here, now my bike runs great, except it doesn't start worth a darn. Now, I currently do not know what ANY of the jetting is (I know, I'm no help to myself or you). Anyway thanks and here's the symptoms. It's about 50 degrees, 600 ft elevation, I know that much.

Has WB R4 pipe, ran like crap. Got advice on setting the pilot screw with the very handy Sears $2 tool. Now it rips, it used to BLUBBER at low rpm, fine on top, now great everywhere except starting.

If I use choke, I might as well forget it. It will start in non-choke mode, but won't get running because it's too cold to run without choke. Eventually if I keep kicking (great exercise btw), it will eventually 'catch' and with some judicious manipulation of the throttle, I can get it going and then it's ok running and starting once it's warm.

I guess the choke making it a non-starter means something's too rich? Also, if I have the idle set high, does that cause problems starting?

THANKS GUYS, this site is the best. I promise I will learn my jetting specs. What specs should I know? This is my guess.

Main jet

Pilot jet

Pilot screw setting (# turns out counterclockwise?)

Needle clip position?

Needle type/part #?

Thanks again!

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Can't help you much, but yes having the idle set too high will hamper starting ability b/c too much air gets in there. That may be why you're having your trouble. Is it set so high that it's a straight hum? Or is it low enough to be uneven (like from the factory)? If it is a straight hum it's too high, bring it down to just under that and you should be fine.

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My 02 YZF was a bear to start when the temperature outside was cold. The colder it was, the harder it would be. Between the end of November and last week, I was able to get it started twice (and only after kicking till I was sweating).

Last week, I had the 03 e-cam installed. In 30 degree weather, 2 spurts of gas, and a handful of kicks and she fired up. I've started it 3 more times since then (temperature never above 50) and it started within 6 kicks each time. My bike went from being a beast to start to being easy enough that I could probably do it bare foot.

You should seriously consider getting the e-cam mod - it is well worth it.

Darryl

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> If I use choke, I might as well forget it.

this indicates you are too rich on the fuel screw. one easy way to test for this is to try starting it COLD with the hot start button pulled out (which leans the mixture by allowing more air in). if starting it cold with the hot start ON is easier than with it OFF, you need to tweak your fuel screw. it is located on the bottom of the carb, pointing up. you don't need to disassemble anything to get to it. but you'll need a proper tool to adjust the screw -- a power screwdriver insert bit works ok. do a search on "fuel screw" and you can find all kinds of little tool tidbits, like the sears/craftsman "knob thingy" that Av recently posted pictures of.

you want to turn the fuel screw IN, which is UP since the screw is upside down. take a half turn IN at first then try starting it again.

i think everyone who bought an '01 WRF had to do this; yamaha can't get everyone's jetting "spot on" due to altitude and fuel changes etc.

jim aka the wrooster

'01 wr250f

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FNR = Fired (sometimes several times), won't stay running

NF = No fire

HS = Hot start, 1 = ON, 0 = OFF

Choke, 1 = ON, 0 = OFF

Idle = turns clockwise, is a very rough approximation

Pilot = turns counter-clockwise from fully seated

Throttle = I gave it some gas to make the A/P squirt some gas into the carb

I tried each setting about 10 kicks.

In between tests, I open the compression release and kicked at least 10 times to clear it out

Do the math, that's about 350 kicks and man, I'm tired!

The one constant I can see is that the Hot start must be engaged to

get it to fire at all, which means to me something is too rich.

I started messing with this because it runs like turd

at low rpm, too much gas too quickly causes it to gasp and die

or maybe if you're lucky you can 'save it'. By richening the

pilot screw, I got it to run like a champ, snappy as can be.

Then it hasn't started since, so I've been doing this.

I'm just trying to get a hint on a direction to go, it seems

like I've got conflicting goals. Richening the pilot screw

made it run great, but now I can't even get it to start!

I was gonna go riding tomorrow!

Thanks for your help in advance.

HS Choke Idle Pilot Throttle Result

---------------------------------------------------------------------

1 0 0 1.5 2 fnr

0 0 0 1 2 nf

1 0 0 1 2 nf

1 0 0 2 0 nf

1 0 0 2 0 fnr

1 0 0 2.5 0 fnr

0 0 0 2.5 0 nf

0 0 2 2.5 0 nf

1 0 2 2.5 0 fnr

1 0 3 2.5 0 fnr

1 0 3 1.5 0 fnr

1 0 4 1.5 0 fnr

1 0 5 1.5 0 fnr

1 0 5 2.5 0 fnr

1 0 6 2.5 0 fnr

1 0 7 2.5 0 fnr

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In order to really get some help here you need to tell everybody what your current settings are. I am up near Chicago which is about 670 ASL and the temps. should be close to yours, and I think that I can help you get that thing started in a couple kicks if you tell us your specs.

Please tell what needle you are using and clip position, pilot jet, and main jet. Also, are you running an aftermarket silencer?

Did you buy this bike new and have you ever had it to the point that it started good?

I know that you what to get out riding but we need to get this think starting good for you or your day of riding will just suck anyway.

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If any of these sound wrong (ex: I wrote down 950 on main when it's always between 120 and 180), please let me know.

Main jet = 178S

Pilot jet = 40

Needle jet = (no #, is this right?)

Needle type = 0BEK P

Clip position 2 from the top (of 7 total)

Starter jet = 72 (hard to read, the 2 ran off the bottom, does it sound right?)

I'm guessing these are all stock settings. My impression (not necessarily correct) was that the previous owner (a kid and dad if I can believe the seller) slapped the pipe on it without jetting it, never could get it right, then sold it.

Do these appear to be stock settings?

THANKS VERY MUCH FOR YOUR HELP !!!!

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The pilot looks small. My WR came with a 42 and the dealer switched it to a 45 before I ever got it. I would also reset the idle and change the plug. To reset the idle take the black cover off the right side where the throttle cables go in to the carb. Back the idle screw all the way off until the screw just touches the cam, then turn it six full turns in. This will be the starting point for idle speed, you may need to adjust it once the bike starts running.

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It sounds like you are rich on the pilot circuit: won't start unless hot start on, won't start with choke on, runs like crap at low RPMs. However, your pilot jet is only a 40 which is typically on the lean side for this bike. I run a 45 pilot jet but I am in warmer climate. Your needle clip position is also quite lean, but that should not affect starting but may run like crap up to about 1/2 throttle.

So we have a dilema. Symptoms are rich but jetting looks lean, especially given your aftermarket pipe. Time to experiment.

First, pull you pilot air jet and clean it out very good. This jet can easily clog with filter oil and if clogged would make any size pilot jet rich (no air).

Second, make sure your slide is not in upside down. This is a common mistake, and although your symtoms are not classic, its worth checking.

If neither of the above are the problem. I would actually try to richen the pilot and needle even though that seems counterproductive based on your symptoms. Try a 42 or 45 pilot jet and put the needle clip in the 3 or 4 position.

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I can't see through the carb at all unless I twist the throttle grip.

Does that indicate a slide in upside down?

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Check your float level too.

And have your carb cleaned.

Good luck.

Does anyone know if this is the part # for an 02 Leaner than stock needle?

5JG-14916-E1 Thanks.

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The stock settings are as follows:

Main jet - 178

Pilot jet - 40

Jetneedle - OBEKP clip position 4

Leak Jet - 100

My current settings are:

Mainjet - 182

Pilot jet - 45

Jet needle - OBEKN clip position 5

Leak jet - 100

The first thing that I would do is set that clip position to 4. You may need to change this once you get it started because of the aftermarket pipe but lets start there. Then I would richen the pilot and main a step or so. We had great temps today but we are probably going to be in the 50's for a few more weeks at least. So you need to be richer than stock for sure.

My bike starts right up. Even after sitting in the garage all winter 10 kicks and it started right up. I just put the 03 exhaust cam in last night and man it's a different bike. Spend the money and get that part. Changing to the 03 cam just changes an already great bike into a perfect bike.

One final thing about the carb. You would be smart to pop that baby off, remove the jets and clean it good with contact cleaner and compressed air. If you don't, and it's clogged some where, you will just be chasing your tail with jetting changes.

Good luck

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I was looking at your jetting specs again and I saw that your starter jet was at 72. I am guessing that this is the leak jet. The standard leak jet is 100. I would get it back to that. because the 70 or whatever is in there now is really rich. It may be that the previous owner tried to adjust for off the bottom bog by changing that jetting. My main idea here is to get most of the jetting back to stock except for the clip position and main jet as described in my previous post. On those I suggested to leave slightly richer because of the outside temps. Then I think that you will get it started. Then you can fine tune the jetting.

Be sure that your pilot screw is not way out of wack also. Put it at about 1 3/4 out for now. Adjust it later once you get it starting good.

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What I'm hearing:

1) Clean the carb. - I have pilot jet soaking in contact cleaner, I looked at the main and the needle jet, the holes are huge and obviously not blocked. Also, I looked at the starter jet, whatever that is, it's also a big hole and obviously not clogged.

2) Jet it richer on the pilot and main. - This sounds good, as everyone else runs richer, but mine is exhibiting symptons of richness already - hot start required to make it fire - so I'm not sure?

3) Change the clip setting - was 2 (from top), changed to four, which also makes it richer. Hmmm. I did that.

4) Set idle setting back to stock. This may be something. It's an easy thing to check and try.

The funny thing is, I rode it a couple of days ago. I got it started (it was hard), then I messed with the pilot screw (went from 1.25 or so to 2.x, made a HUGE difference). Went out and rode it, ran like a top, all over, no more bog off the bottom, ran like a champ on top, PERFECT, that was Thursday night. Tried it Friday, no joy. Tried all day yesterday. It would fire briefly then die, that was yesterday. My leg and back were too tired to kick it again today! I did learn the jetting and learn how to take the sub frame off, that was cake.

I wonder what changed? I haven't tried it since I changed the clip and I need to reset the idle and put it back together. I'll try the needle clip change and the idle setting and report back tomorrow night.

THANKS FOR THE HELP !!

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I got it back together tonight after cleaning the pilot jet and dropping the clip from 2 to 4 (richening it) and setting the idle stock (six full turns out from barely engaged) . Wouldn't start on choke, flipped it completely from choke on-hot start off to choke off/ hot start on and THAT SUCKER FIRED RIGHT UP !! WOO HOO !!!!!

Now the bad news. I left the gas on and came inside. Went back out ten minutes later to try it again and there was a big puddle of gas on the floor. It's coming out of the bottom-most drain hose on the carb. I assume this is the overflow and the float must be sticking. The floats fell off when I had the bowl off and the pin just dropped out. I saw the pin hit the floor and had no idea what the heck it was (looks like a needle bearing!), then the floats hit a second later and I knew.

Is the float needle a one-way thing? It's no biggy to pull the bowl and swap it, just wondering so I don't chase my tail anymore as I WANT TO RIDE NOW!

BTW, it runs like a top, no bog on the bottom.

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That sounds just like my problem. My bike won't start with the choke on as well. Check out my post.

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this indicates you are too rich on the fuel screw. one easy way to test for this is to try starting it COLD with the hot start button pulled out (which leans the mixture by allowing more air in). if starting it cold with the hot start ON is easier than with it OFF, you need to tweak your fuel screw. it is located on the bottom of the carb, pointing up. you don't need to disassemble anything to get to it. but you'll need a proper tool to adjust the screw -- a power screwdriver insert bit works ok. do a search on "fuel screw" and you can find all kinds of little tool tidbits, like the sears/craftsman "knob thingy" that Av recently posted pictures of.

The link to the "knob thingy" is in my sig below... :)

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based on your recommendation. Easily the best 2 bucks I EVER spent!

So you're saying I need to go leaner on the pilot screw (and may end up leaner on the pilot jet if I have to go too far). Must be that White Brothers pipe, my jetting is stock and it seems that stock jetting tends towards lean, based on what I've heard other people here running on theirs. Hmm.

Thanks, I do surely appreciate the help.

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Umm, that's actually wrooster's recommendation, but it sounds good to me for your situation... :)

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