250sx carb issue, idles fine, dies if throttle is touched

[barnett468]

Lower


Oh ya, I forgot, I also moved the slider needle down a notch hoping to make the midrange throttle more rich. No change...."


Lowering the needle made it LEANER not RICHER, raise the needle all the way by lowering clip.


There is no such thing as a "slider" needle, are you talking about the adjustable needle in the slide?

[UPNATM]

Hello


You would have gotten more responses as a new thread

"It is running lean, because when I choke it it runs fine, under a load, but without the choke, it stumbles, and falls on its face."

Did it run fine before you parked it? If yes your gas is bad or idle circuit is plugged.

If it ran bad before your PILOT jet is too smal NOT the main based upon your description.

I didnt start a new thread, because I thought the mods might get pissed. A lot of other forums I am do not like it when you start a new thread with he exact same issue that is already being discussed in another thread.
Basically, its been sitting for 20+ years inside, until a month and a half ago. When I parked it way back when,I pulled the battery, and drained the fuel.
But ya, it ran fine until the rear end bearings got fried.
Pilot jet huh? Are they marked with a size like the main?

[UPNATM]

Lower


Oh ya, I forgot, I also moved the slider needle down a notch hoping to make the midrange throttle more rich. No change...."


Lowering the needle made it LEANER not RICHER, raise the needle all the way by lowering clip.


There is no such thing as a "slider" needle, are you talking about the adjustable needle in the slide?

Yes, the adjustable needle in the slide. And I misspoke, I lowerd the clip down a notch from the factory setting, in essence raising the needle up.

[barnett468]

What about the gas, new or old?

Yes the pilots are marked.

Did raising the needle do anything?

Raise it all the way and try it.


If it absolutely positively ran good 20 years ago it is NOT your jetting unless you are in a much colder climate now. This means your idle circuit is not 100% clean.

[barnett468]

Hello


I suggest you start a new thread here in the future. Having to look up an old thread with a problem similar to yours to post your question in so a moderator doesn't yell at you makes no sense to me for many reason's.

[UPNATM]

What about the gas, new or old?New gas, petcock, and a clean tank.

Yes the pilots are marked.Ok, ill take another look, thanks.

Did raising the needle do anything?Once it gets past the bogging and clears up it sputters and backfires slightly with the needle raised. That's why when I moved up in jet size, I moved the needle back to the stock setting.

Raise it all the way and try it.Ok, ill check it out...


If it absolutely positively ran good 20 years ago it is NOT your jetting unless you are in a much colder climate now. This means your idle circuit is not 100% clean.Yep, it ran great, and im in the same climate. Ive gone through the carb three times, and it looks/seems clean to me. But, I will take another look.

Hello


I suggest you start a new thread here in the future. Having to look up an old thread with a problem similar to yours to post your question in so a moderator doesn't yell at you makes no sense to me for many reason's.

Ok, will do.

[Dave8338]

One other thought. The intake O-ring on the intake tube between the head and the intake, gets hard, flat, and cracked. I would pull the intake off and replace that o-ring along with the o-ring on the carb. These are the first two things I do when starting a new (old) bike service. I've dropped old carb/intake o-rings on the shop floor just to see if they will break. About half the time, they do. Cheap easy insurance for a good running bike.

Good luck

[UPNATM]

One other thought. The intake O-ring on the intake tube between the head and the intake, gets hard, flat, and cracked. I would pull the intake off and replace that o-ring along with the o-ring on the carb. These are the first two things I do when starting a new (old) bike service. I've dropped old carb/intake o-rings on the shop floor just to see if they will break. About half the time, they do. Cheap easy insurance for a good running bike.

Good luck

Thanks! Ill give it a try....

[barnett468]

Hello

dAve8338 has an xlnt suggestion. You can check for intake leaks by starting your bike hold throttle where it is lean, and spray FLAMMABLE brake cleaner in SMALL amounts around the intake at the head. It will instantly increase in rpm if you have a leak. If you do not have a leak now but remove the intake to inspect o ring you may create a leak when it is reinstalled.