250SX carb issue???

[Big Sal]

My other thread on this subject you can't get to the second page....it says it's forbidden...????....anyway....I tried something stupid today....I reached down an squeezed the intake tube from the frame to airbox so it would choke off the carb....and the thing took off like a raped ape!!! So my question is this a simple needle adjustment or a jet change?? I realize that cutting off the air tube changes the ratio and fattens up mixture, I don't think there is enough adjustment in the needle to do it, or could it be something else?

[tri again]

My other thread on this subject you can't get to the second page....it says it's forbidden...????....anyway....I tried something stupid today....I reached down an squeezed the intake tube from the frame to airbox so it would choke off the carb....and the thing took off like a raped ape!!! So my question is this a simple needle adjustment or a jet change?? I realize that cutting off the air tube changes the ratio and fattens up mixture, I don't think there is enough adjustment in the needle to do it, or could it be something else?

I noticed that.
I think 007 replied and I've been triying to follow.

Can you recap?
or?
Since you are essentially manually 'choking ' it,
Do you think your 'enrichment piston' that is pulled up by the choke cable is working correctly?
full throw?
The other pita is IF it's a qa 01 carb, the cold start jet can make a grown man cry.

If it was never recalled and fixed, the only thing to do is
start fluid, choke the sucker with you hand, look around before you scream obscenities
and look for the elusive cold start replacement jet,
or hope you can drill it out to the correct size.

I could go on but not sure if I'm barkig up the right tree here.

Search key for 'cold start' may help.

Does it start easy when warm?

[Big Sal]

Starts right up cold or warm...choke does work correctly when it's cold by increasing the RPM as expected....that's why I never questioned the carb because when I apply the choke it doesn't run any better...but when I "choke" off the air by the tube, it picks up like a scaled dog...I'm thinking I have to increase the main from a 130 to ?....I don't think I can get enough adjustment out of the main needle without messing up the other ranges on the carb...that's why I'm thinking it has to either be under jetted or there is another "fuel" related issue....any thoughts?

[tri again]

Starts right up cold or warm...choke does work correctly when it's cold by increasing the RPM as expected....that's why I never questioned the carb because when I apply the choke it doesn't run any better...but when I "choke" off the air by the tube, it picks up like a scaled dog...I'm thinking I have to increase the main from a 130 to ?....I don't think I can get enough adjustment out of the main needle without messing up the other ranges on the carb...that's why I'm thinking it has to either be under jetted or there is another "fuel" related issue....any thoughts?

oh, ok. this thread got busted up so not as easy to follow.

I thought by squishing the air intake tube, you were essentially choking it (like to get it started)

I posted the stock jet sizes on here recently but can do it again after I get away from work in a few hrs.
Hope fully 007 will come back and save the day (again)

[Big Sal]

Squeezing off the intake tube does choke the carb...like an old fashoned butterfly choke...I'm just wondering if the enrichment type choke, because it enriches, instead of choking off the air, is the reason why choking off the air at the tube has a different effect than just enriching it thru the carb itself...either something is still plugged up or I have to jet up from the stock 130 jet....I'm gonna try to adjust it with the needle and re-sync the carb again...what do I have to loose....lol

[Headsup]

Just wonderign if your Cold start plunger, Or choke cable is still attached? Or is it allowing air to pass threw/>? Have the same problem. Mine is cracked and air get threw.. Does the same thing, I havnt got a chance to get a a new one and see if it fixes it up.

[Big Sal]

I sprayed all the fittings on the carb with starting fluid to see if the engine changes speed because of a leak, and didnt notice anything...

[tri again]

so it would be happier with more fuel?

Not sure if any jet change or adjustment would be as dramatic as cutting off the air to that extent.
Could a jet have been 'misplaced' before you got it?
I think if they could go in the wrong sequence, I would have done that by now. IDK
Vac leak? but you checked that.
I'm stumped.!
Luckily, I have an 'extra' known working carb.
If it's a QA01, they'll fight you till the last straw of comprehension.
Been thru like 9? of them in the last year.

I DO like the aftermarket pumper carb with the flipflapper choke for the 250 engines.
I just take it so personally when I can't figure stuff out, I'll work on it even if I have
a quick fix on the bench, ready to resolve the issue.

[Big Sal]

Were these carbs always a problem child on these machines??? Give me a good ol Mikuni anyday!!!! I'll be damned if I can figure it out....but I will....like you Drjoe....I can have a quick fix that would solve the problem, but I wanna find out why there was a problem in the first place...lol

[86trizinger]

I have a stock carb on my 250sx. Works great with no issues. Never had to change the jets in it even with the Bassani exhaust and UNI filter. Are you sure the fuel is flowing freely out of the tank? That is the only issue I had with mine.

[dougspcs]

Maybe I'm missing something or I missed the 1st part of the conversation..

What is the point to squeazing the tube?? Or were you just trying something and expecting a different result?

[Big Sal]

I was just trying something and expecting different results....when I try the factory "enrichment" choke to see if it running lean, I get no change in the bogging top end...when I squeeze off the frame to airbox tube, I get no bogging...straight to top end...I've checked for air leaks thru the whole intake system, the only thing I can figure out it the carb is just bad...I've replaced the coil, CDI, checked all the grounds and connections, tank is clean and the petcock is clear...I'm pretty much down to the carb again...unless somebody has any other suggestions...

[dougspcs]

I assume you have removed and cleaned the carb, checked fuel flow from the tank..etc?

[atc007]

I was just trying something and expecting different results....when I try the factory "enrichment" choke to see if it running lean, I get no change in the bogging top end...when I squeeze off the frame to airbox tube, I get no bogging...straight to top end...I've checked for air leaks thru the whole intake system, the only thing I can figure out it the carb is just bad...I've replaced the coil, CDI, checked all the grounds and connections, tank is clean and the petcock is clear...I'm pretty much down to the carb again...unless somebody has any other suggestions...
Going by this post.. Have you taken that tube completely off? So the airbox is really sucking ! We'll assume that's gonna make it real sick. It is the carb. You know that. I guess we just go about 2 or 3 on the main and see what it acts like. What does your plug look like? You want a nice dark brown to light black,,especially heading into winter.

[Big Sal]

I didn't remove the tube, I just squeezed it off cutting the air and changing the air/fuel ratio...it was just a dumb thing to try but it worked...lol!! So at least it gave me a direction to go....it's definitly in the carb..I richend the main circut by rasing the needle one notch, it seemed to help a little but not enough that I could adjust it out, plus I know that the main needle adjustment has to affect low and midrange also. The carb has been taken off before, so I don't know what the previous owner did to it...I cleaned it quite a few times...it was really mucked up badly....maybe something is still plugged up, anyway I scored a used one from eBay off a running unit for $40...I figure I'll start from square one, with a hopefully unmolested carb...give it a good clean and put it on...and cross my fingers it solves the problem. I just didn't know if cutting the air into the airbox would point to a different direction (like a jet change) or somebody has come across this situation before and figured out the deal with it.

[dougspcs]

Did you look carefully into the carb body after you removed the jets..maybe the something foreign is lodged in there. Or perhaps something fell out??

Double checked the vacuum routing??

Look at the exploded parts listing in the manual and compare it to your carb!! There has to be something you aren't noticing because it was never there..

Maybe this is the result of the previous owner..I just inherited a carb issue like that, missing spring in the idle mixture jet. Thankfully I had an old carb to rob from.

These carbs are pretty reliable if they are maintained..I have 4 machines with this style of carb and after cleaning and proper setup they are all excellent.

[Big Sal]

I thought I did a good job of checking everything...the only thing the carb was missing was the baffle on the main jet (in the bowl)...I read that people are running their carbs without the little baffle with no problems...I get this carb in I'm gonna go thru it and clean it good...put it together with genuine Honda parts...install it and keep my fingers crossed...lol

[dougspcs]

I think you got it right..wait til the 'new' carb arrives..strip, clean, and install..

Bet you it will be right as rain!!!

[atc007]

She'll be as new with another carb! Then you'll be tinkering till you get this one squared away ,,won't you ! I would!

[tri again]

Did we mention the emulsion tube that hides UNDER one of the screw in jets?

..about an inch long, full of holes and usually packed with muck?

This thread got separated so not sure if we covered that.
I missed that thing 2x on my first go 'round.

I got so annoyed with one, I blew air into it under water to see if/where bubbles came out...
compared to a known working carb.

I can't even imAGine what it took to design the internal passages, and partial openings and
cross connected vacuum dependent atmospheric suckulater valves, Boyle's law of fluid dynamics and
compression and expansion physics etcetc jeeeeze!

Obsessed?
you betcha

GF kicked me out of the kitchen for almost a month over that episode.

ps
jet numbers from float valve first are:

Float
130 main
38
press in cold start
45
and then the
pilot screw

Still not sure which one of the screw in jets that mucky emulsion tube hides under.
I forget, thanks to an effective keihin QA01 PTSD.

Nice save btw.
I saw pics of your project on another posting.

These things are so sweet when they run right, you'll forget ALL about the pain...
and which jet the emulsion tube hides under.
and which way the little tiny arrow on the air boot faces.
but it's all part of the healing process.

[Big Sal]

Tiny arrow on what air boot? I thought they only went on one way? Thanks for the complement...she was rough when I got her....I literly pull her out of the weeds...but I could see her beauty under all the rust and corrosion...my wife, mmmm....not so much...I got the "what are you gonna do with that piece of crap" comment...lol

[tri again]

Tiny arrow on what air boot? I thought they only went on one way? Thanks for the complement...she was rough when I got her....I literly pull her out of the weeds...but I could see her beauty under all the rust and corrosion...my wife, mmmm....not so much...I got the "what are you gonna do with that piece of crap" comment...lol

Yupp, tiny little arrow on the long 's' shaped airboot.
Still a mystery to me or I'd tell you.

Shine it up and put some flowers on it and it's Hers!
Mine still has her flowers strapped on it from a year ago.

THEN you simply get another one,
and another one
and join a support group where we get very little sympathy
and marginal (world class) tech support.

I just listed an sx and the guy coming over wrote a book about
relationships.
I think there's even a 3 wheeler section in there.

What a great excuse for a romantic ride in the country.
A picnic basket, and a camera and memories are created.

[Big Sal]

I've definitly gotten lots of help on here....
I'm hoping that the carb I'm getting is unmolested....I got it for $40 shipped so the price was right...considering a new one is over $100....if it's not too ragged I'm just gonna clean it and put it on.

[Big Sal]

Well guys it must have either been the carb or the Moose kit....got the "new" carb....cleaned it good, got a factory Honda kit....and she runs like a bear!!! Pulls straight thru to top end...no bogging...no hesitation...no nothing!!! The darn thing was kinda scary...lol...it took off and ran so good it suprised me....I almost ended up on my trailprotrailprotrailprotrailprotrailpro....I really appreciate everyones help you guys are #1...I did buy a CDI that I didn't need but that's OK...not a bad thing to have a back up...so now its back to saving my pennies for a Clark plastic tank, factory rear rack and getting my seat cover installed!!