250 The 1999 YZ250

Mihylo33

Mihylo33

Trfsrfr:
@Andy, I have no problem taking the advice of 9.5 out of 10 people on this site, you guys are awesome.

But you need to understand that sometimes I am too smart for my own good, my own worst enemy some days, and often times a complete and total moron, like right now.
I've been out in the garage messing with this thing for last few hours and been scratching my head...
So I went back to square one and lo and behold, I find my dumbass relearning the basics.
It turns out that this engine (and I assume others) actually needs gas to run! :doh:
Who'da thunk!? :noidea:

I still need to dial it in more, but I took it for a rip around the block and she accelerates nicely, doesn't sputter, and generally runs closer to like it should.
In my haste while first getting it going I only put in a small amount of fuel because I didn't know how long it would take to get it running and I didn't want to have a bunch of gas go bad, or be lifting a heavy tank on and off again a million times.
Dipshit I am.
Click to expand...


We've all been guilty of that once in a while.
Did you go fatter on the jets yet?
 
Trfsrfr

Trfsrfr

Mihylo33:
We've all been guilty of that once in a while.
Did you go fatter on the jets yet?
Click to expand...
No, not yet.
I was gonna leave the track early this past Saturday to get to the bike shop before they closed at 1pm, but the kiddo was having too much fun so we stayed until closing time, which was 1pm.
But now that it runs better, I am gonna keep messing with it and try and get the air screw figured out. It runs like I have never seen it so I am basically back at square one, not only with the way it runs and sounds, but with my learning curve. Also I found that the air screw is missing the washer that sits behind the o-ring, so I am gonna order a new one. Right now it's sitting against the spring.

I work tomorrow but have the next 3 weeks off so I plan on taking it out to the desert and doing another plug chop test and see what the results are this week. I am questioning whether I did the previous plug chop tests right and was possibly getting incorrect readings. I'm thinking maybe I didn't have it opened up enough and under enough load for long enough time..
And I am thinking when I order jets I might end up ordering a bunch, maybe a kit if I can find one for a reasonable price. I think it makes sense for me to have a range of jets above and below what I have now, for future tuning.

I am looking forward to getting home tomorrow and bringing her out to the desert to see if the sputtering problem is fixed. My residential streets are not the best place for test drives...
 
Last edited:
PALMER84ONE

PALMER84ONE

Trfsrfr:
No, not yet.
I was gonna leave the track early this past Saturday to get to the bike shop before they closed at 1pm, but the kiddo was having too much fun so we stayed until closing time, which was 1pm.
But now that it runs better, I am gonna keep messing with it and try and get the air screw figured out. It runs like I have never seen it so I am basically back at square one, not only with the way it runs and sounds, but with my learning curve. Also I found that the air screw is missing the washer that sits behind the o-ring, so I am gonna order a new one. Right now it's sitting against the spring.

I work tomorrow but have the next 3 weeks off so I plan on taking it out to the desert and doing another plug chop test and see what the results are this week. I am questioning whether I did the previous plug chop tests right and was possibly getting incorrect readings. I'm thinking maybe I didn't have it opened up enough and under enough load for long enough time..
And I am thinking when I order jets I might end up ordering a bunch, maybe a kit if I can find one for a reasonable price. I think it makes sense for me to have a range of jets above and below what I have now, for future tuning.

I am looking forward to getting home tomorrow and bringing her out to the desert to see if the sputtering problem is fixed. My residential streets are not the best place for test drives...
Click to expand...

Give me PM your address, I'll mail you a washer and o-ring to replace.
 
Trfsrfr

Trfsrfr

Well, took the bike out for a ride today... no go. I was so hopeful.
I think I'm getting close though.
It feels like it rev's smooth until it hits the powerband, then it get choppy and sputtery.
Did a real good plug chop on it though, but forgot a new spark plug.
I haven't pulled the plug yet but I may try and get a look at it tonight...maybe. It's cold in the garage right now.
If not tonight tomorrow for sure, and I am going to go and purchase some jets from the local bike shop.

So couple more questions;
1 - how many other things can be causing this issue? If I got fresh gas, compression, spark, timing...what else is there?
Would the reeds cause it? Or how about that fuel cut-off switch?
2 - This thing needs a chain and rear sprocket bad. My buddy Danno has some new bulk chain I can use, but where to purchase a decent but inexpensive sprocket? Steel or aluminum?
 
Mihylo33

Mihylo33

Trfsrfr:
Well, took the bike out for a ride today... no go. I was so hopeful.
I think I'm getting close though.
It feels like it rev's smooth until it hits the powerband, then it get choppy and sputtery.
Did a real good plug chop on it though, but forgot a new spark plug.
I haven't pulled the plug yet but I may try and get a look at it tonight...maybe. It's cold in the garage right now.
If not tonight tomorrow for sure, and I am going to go and purchase some jets from the local bike shop.

So couple more questions;
1 - how many other things can be causing this issue? If I got fresh gas, compression, spark, timing...what else is there?
Would the reeds cause it? Or how about that fuel cut-off switch?
2 - This thing needs a chain and rear sprocket bad. My buddy Danno has some new bulk chain I can use, but where to purchase a decent but inexpensive sprocket? Steel or aluminum?
Click to expand...


Bump those jets up Cuz!
 
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