SX keeps on running rich

[ailll1]

Alright, my 85 Sx is giving me hard time. Changed the carb couples month ago, had great result but now it wont run with the right air/fuel mix. The thing is running really rich(lots of black carbon deposit on spark plug).Wont idle at all when hot unless i change the idle setting and smokes black at WOT.

Tried to interchange jets from my old carb, no changes. Moved the needle to the top notch, lil better but still.
Now im thinking that my exhaust might be clogged up from having sitting 1-2 years in a barn. Air flow being restricted would cause it to run rich?

Any ideas would be awesome guys
Thanks

Heres a pic of the trike:pics:

[Thorpe]

On my 85 ES, I had gotten a rebuild kit that had the wrong jets in it... And after digging in real deep to the books, there is a different carb kit rebuild for 85 vs. 86&87... (just my experience) Mine was running really rich as well, fouling plugs and wouldnt idle....

[ailll1]

All the jets have concording numbers to the stock ones.
Oh and I noticed that both carb dont have the same model number on them
The stock is a QA02 and the one is on right now is a QA01
Maybe thats the problem?
From what engine does the QA01 comes from?
Note: Bought it on ebay and was listed 85 250SX carb

[cbx1170]

spk plug DR8ES-L or eqiv. verify float height, watch for small red rust oxide particles flowing down from fuel tank !!! , use good nylon fuel filter Not the sintered brass cheapies they let small crap thru that wont allow float needles to seat , no obstruction in air box, lastly needle jet and jet needle the part that hangs down from slide and the part that is visible just sticking into carb bore wears and lets too much fuel thru. replace as set. Yeah some cheapo carb rebuild/repair kits actually have wrong jets and not the best jet needles. fuel jets realy dont wear. float needle/black tip wear and distort, jet needle/needle jet (look at the top of the long needle below clip, low rpm area) combos do. remove muff and shake...... noise=bad clean it out.

[Thorpe]

Also, make sure your choke cable is routed correctly, and your choke plunger is correct... I had to put a cable tie on housing, at the top of the carb rubber boot to cable on my BR... The cable would pop out of the little notch it was suppose to ride in, and get held up slightly... (running some choke)

[ailll1]

Spark plug is ok

I dont know about float height but ill check that out, it cant be adjusted on the SX can they?
Already got a fuel filter hooked up that I bought from canadian tire but I don't know if its the crappy one. Collects lots of stuff tho.

I thought about the part visible from the bore of the carb as you call it being worn.
The needle doesnt really sit on anything, the slide sits before the needle.
Are these included in carb kits on ebay?

Messed with the choke some and everything seems right.
Plunger doesnt seem to be held up.

Everthing else is alright, so I guess I'll try one of those rebuild kit on ebay!
Thanks guys

[Thorpe]

The float is not adjustable in stock form (per say) I adjusted mine on my ES... Its kinda a secret way how. And depends on whether you are old enough to have a beer... :naughty: I cut up little tiny pieces of shim (aluminum beer can) and shimmed between the float and the needle... Guess it could work with a coke too, but thats just not as much fun....

[whyzee]

dirty air filter ?

[cattle-dog]

i am going to ask the most forgotten question hows the airfilter if its dirty it will run rich sometimes wont even run, unless its new i would try to see if it runs better without the airfilter. dont ask how i know it can happen as its one of the dumb moments i would like to forget lol.

[cattle-dog]

dang whyzee beat me to it

[ailll1]

ROFL!
Redneck Engineering isn't it?
Your Big Red had any problems staying on the trails after that?
And any beer burp?

[ailll1]

No changes with the air filter off.
Cleaned it couple weeks ago and reoiled it also.

[Thorpe]

No... No, beer burps at all! Well it was kinda funny, because I was working on the BR here in the garage one evening, fighting that stupid carb, got frusterated and came inside, sat down, cracked a beer and got on 3ww... Someone told me to check the float height, and sure enough it was out of spec, and not adjustable. So, pissed off, I had started working a tear into my beer, trying to come up with how I was gonna fix this, as the new floats have been discontinued for awhile now, and I thought to myself, WWJD? No, no, not Jesus, but Jim, (my boss) and I knew he would dig in the machinist box, and get out some shim stock, and shim away... Now mind you, the shop was a 30 minute drive away from my house and it was 930 at night.... So.... Short story long.... I have been rocking it that way for a year and a half and it runns like a top, and has never given me any issues. Its only redneck if it works for a minute! After you get done with that beer and shim your float, you will think, that crazy MN boy was on to something!

[ailll1]

Nice redneck definition
I'll have to check that for sure if it made that much difference for you
Thanks bud

[whyzee]

No changes with the air filter off.
Cleaned it couple weeks ago and reoiled it also.

...too much oil in the filter. Is this about when the problems started?

no changes with the filter off?? hmmmm

I was thinking mice built a nest in the downtube where the air comes into the filter. Restricting airflow and causing rich/poor running conditions.
gotta be in the carb. go for a new one.

[ailll1]

Problem started when I changed the original carb that was on it before I oiled the filter.
With the old one, it would bog and sputter at not even 1/2 throttle.
So i got sick of it and changed it but now the other one is giving hard time also.
Still did great change on power but my friends BRs are still kicking my ass.

[whyzee]

could be the valves out of adjustment or a faulty CDI.
check the valve clearance with the engine cold
also, take the plug out and ground it against the motor, see if you get a nice fat blue spark.
I don't think the carb is the problem based on your new info

[Thorpe]

Maybe check out the chain tensioner and the cam lobes while you are looking at the valve adjustment.... (no beer can fix for those though...)

[whyzee]

Maybe check out the chain tensioner and the cam lobes while you are looking at the valve adjustment.... (no beer can fix for those though...)

ditto! I am thinking it is more a motor issue than a carb issue.
Maybe DC will chime in to help us

Is it hard to start also?

[ailll1]

Starts 1 kick when cold but as soon as it gets a little hot, I need to give it some gas for it to start. Has really low rpm when hot also.
Compression's at 160psi so I think that way enough.
Valves been adjusted a week ago.

[ailll1]

Maybe check out the chain tensioner and the cam lobes while you are looking at the valve adjustment.... (no beer can fix for those though...)

How do you check these?
Any tear up?

[whyzee]

I think with the compression at 160, the rings could be worn enough for a rebuild.
I would still double check the valve adjusments you did
Service manual says it would be a faulty cdi unit. IDK about that though
PM Dirtcrasher for some more advice.
Maybe somebody on here will give you a cdi unit to check and see if that is the problem. ask around.
do you have a service manual for the SX or just the owners manual ?

[ailll1]

Only have the service manual, don't think I need the owner manual thought.
The manual says that compression should be between 142 and 170. Isn't 160 within specs?
I don't know much about electrical components. Whats the CDI for?And what does CDI stands for?

[whyzee]

wow, i didn't know the psi was that low on the SX. I only have the owner manual.
CDI stands for..haha hmmmm Capacitive Dischage Ignition ?
it's a little black box that plugs into your ignition/spark plug. Controls your timing and spark. If it is faulty it would defintily cause the issues you describe.

EDIT: i am making fun of myself . I am not sure if that what CDI means.

[ailll1]

Alright, CDI stands for Capacitive Discharge Ignition.
Which issues correspond to a faulty CDI?
If you mean the bogging and sputtering at 1/2 throttle thing, this was with the other carb that was on, not doing it anymore.
Engine revs pretty high but wont hit the rev limiter or whatever you call it(steady rpm at full throttle) and has not the power it should have.

[whyzee]

it really does sound like the cdi unit.

[whyzee]

any luck yet ??

[ailll1]

Checked the valves, exhaust had .001'' too much clearance, intake was on specs.
Did tried Thorpe's beer can shim. Float level was sure outta specs about 16mm when it sshould've been 18.5mm.
But it made no change at all.
I guess I'll have to wait for my carb kit to come in and see If the carb really is the problem.

[whyzee]

gotta be frustrating. keep looking for a cdi unit .

[ailll1]

yeh, I'm kinda sick of keepin working on it without any noticeable changes.
I'll try to borrow 1 from my friends BR (I guess it's the same?) and see the difference.
Not hard to swap so wont be really long to do.

[whyzee]

yeh, I'm kinda sick of keepin working on it without any noticeable changes.
I'll try to borrow 1 from my friends BR (I guess it's the same?) and see the difference.
Not hard to swap so wont be really long to do.

It is pretty easy to swap out. much easier than doing the carb. I am also wondering , since you had good results for a short while after the new carb install, could your fuel tank be dirty/rusty and clogging your carb? check your fuel filter and see if it is dirty. That could be your problem right there. Cleaning it won't solve the problem because your carb could already be clogged ( if this is the problem ) . Can't hurt to pull it out and check/clean it.

[Thorpe]

Checked the valves, exhaust had .001'' too much clearance, intake was on specs.
Did tried Thorpe's beer can shim. Float level was sure outta specs about 16mm when it sshould've been 18.5mm.
But it made no change at all.
I guess I'll have to wait for my carb kit to come in and see If the carb really is the problem.

What kind of beer? That may have something to do with it! ;) Hopefully that rebuild kit will straighten you out... Where did you order the first rebuild kit from?

[MTS]

So it runs fine and Pulls the Rpm's when its cold? But once it heats up it runs rich...? ...besides the fact 4 strokes Normally run a little richer when hot, I would Check your stator and Mag out....Check your Ohm specs cold..then Hot when it starts to act up...see if there is a Significant difference, Could be a Weak ignition..Not a clean burn....Hence the black smoke and Rich condition...This is taking into account all the other Advice and things checked.

[ailll1]

It is pretty easy to swap out. much easier than doing the carb. I am also wondering , since you had good results for a short while after the new carb install, could your fuel tank be dirty/rusty and clogging your carb? check your fuel filter and see if it is dirty. That could be your problem right there. Cleaning it won't solve the problem because your carb could already be clogged ( if this is the problem ) . Can't hurt to pull it out and check/clean it.

Well the "new" carb did improve perfomances compare to the old one but nothing changed since it's on.
My gas tank is partially rusty. My fuel filter is getting a il dirty but not that much, only have been there for a month or so without any hard riding(maybe 5-6 max tank burned).
Oh and that leads me to the fact it's burning around 1.5 more fuel than my friends BRs burn.
You dont know how many time I've pull this darn carb apart to clean it and to try everything I could read in the manual.I guess about at least 10 times, cleaning everthing everytime even if there was nothing to clean lol.

[ailll1]

What kind of beer? That may have something to do with it! ;) Hopefully that rebuild kit will straighten you out... Where did you order the first rebuild kit from?

Budweiser for the shim, maybe my trike can't handle men beers? Or either it need another brand?
Here's the rebuild kit I bought out off ebay:
http://cgi.ebay.ca/85-Honda-Atc-250-SX-250SX-ATC250-Carb-Carburetor-Kit-/350323189763?pt=Motors_ATV_Parts_Accessories
34buck shipped here in Canada
Others kits had crazy shipping rates or were doubtful on which parts it contained.

[ailll1]

So it runs fine and Pulls the Rpm's when its cold? But once it heats up it runs rich...? ...besides the fact 4 strokes Normally run a little richer when hot, I would Check your stator and Mag out....Check your Ohm specs cold..then Hot when it starts to act up...see if there is a Significant difference, Could be a Weak ignition..Not a clean burn....Hence the black smoke and Rich condition...This is taking into account all the other Advice and things checked.

It acts like its choked a little bit. Knocking idle when its hot and smooth when its cold as it should be when hot. I havent tried to go full rpm when it's cold becuz I dont want to damage rings and cylinder.
What do they mean in the manual when they say check continuity between...?

[ailll1]

Alright guys, great news.
Carb kit came in tonight and I had time to install it.
My SX runs like a kitty now. Still have to do a plug chop and set the pilot screw but it sounds WAY more healthy now.
Now it's time to see how the SX compares to BR.
Thanks for advices guys

[whyzee]

YEAH!!!!!!! Awesome!!