running rough after carb clean, why?

[bansheemorphine]

I have a 2005 yfz 450, we had a really muddy race on the week end and a little water got into my intake. I took my carb off and cleaned it all out, i took out all the jets and blew them out with my air compressor. i put the carb and everything back on it was all clean as can be and when i started it it wouldn't idle right and when i took it for a ride when i let off it will backfire and pop like crazy. what could this be? there is a black plastic knob on the left side of the carb what is that? any help will make my day. by the way it ran fine when i unloaded it off the truck and put it in the garage before i took the carb off.

[Thumper1220]

I think the nob you are talking about is the choke?

Make sure the choke is not stuck partially open I had a similar problem on a snowmobile....

something might wedge the choke partially open

[bansheemorphine]

no the choke pulls in and out this knob turns left and right

[XCRacer236]

that knob is the idle screw.
turn it right for a higher idle, left for a lower

[Thumper1220]

I would also check the condition of the rubber intake boot make sure it's not sucking air.....if it was cracked a little you could have cracked it open when you removed the carb..... prolly not this but it wont hurt to check.

[daddio]

Did you spray the inside of the carb with "carb cleaner'?

[bansheemorphine]

yah i did spray the inside of it once i had it off and the jets and what not all out

[daddio]

If you get carb cleaner on the slide, it turns the coating soft and the slide sticks. The rubber diaphram (p/n 4FN-14997-00-00 SEAL) will also swell up from the cleaner causing the slide to stick and idle irraticly.

Take the slide out and rinse it and the carb, in just gasoline. If your lucky, all you need is a new seal. If the coating is coming off, it's about $300 for new slide parts.

I've seen this many times.

[bansheemorphine]

i screwed around with it today and i got it idling good now but still when i drive it down my driveway when i let off it will pop like crazy out of the exhaust, could this be the slide thing causing that also or something else?

[daddio]

Originally posted by bansheemorphine
i screwed around with it today and i got it idling good now but still when i drive it down my driveway when i let off it will pop like crazy out of the exhaust, could this be the slide thing causing that also or something else?

That's usually caused by a lean condition in the mid. Raise the needle 1 position.

[bansheemorphine]

i'll try that but i didn't change anything when i took it off when it started doing this and it worked fine before

[Thumper1220]

what does the spark plug look like is it tan or black and damp looking?

no disrespect but if it was fine before, you dont want to go changing the needle position or anything else untill you get a good reading of the spark plug condition.

if the plug is damp I would check to make sure choke is not stuck partially open, all electrical connections (if any) are hooked back up right, also make sure you have a good flow of gas from the tank as well.

if none of this helps I would disassemble it again and check for anything wrong inside. again no disrespect but sometimes you can bend something and the floats could be jammed or something else

[daddio]

Good advice.

[Thumper1220]

check these things and let me know if it helps you any.....:confused:
trying to think of everything.....and the more i think about it it sounds like the pilot jet could be partially blocked...or the float could be stuck.

[bansheemorphine]

ok i'll take it apart again tonight and see thanks for the advice

[Thumper1220]

[i]Originally posted by bansheemorphine there is a black plastic knob on the left side of the carb what is that? [/B]

that should be the idle air screw...black plastic and kinda looks like it has teeth on it like a sprocket right...that screw moderates the air fuel mixture when the motor is at idle...like the jets do when your on the throttle. the popping on deceleration can also be caused by a lean idle mixture. if you turned this screw in or out call the dealer and ask them what the stock setting is (ie 1-1/2 to 2 turns out from full in position... somewhere in there)

just check the plug make sure it's not too lean because your symptoms overall sound like a lack of fuel.

if you can post a picture of the plug on the thread that would help the diagnosis and prognosis too..... just trying to help not step on your toes but i like to help people out and i'm interested now to see where the problems at

[daddio]

Originally posted by Thumper1220
that should be the idle air screw...black plastic and kinda looks like it has teeth on it like a sprocket right...that screw moderates the air fuel mixture when the motor is at idle...like the jets do when your on the throttle. the popping on deceleration can also be caused by a lean idle mixture. if you turned this screw in or out call the dealer and ask them what the stock setting is (ie 1-1/2 to 2 turns out from full in position... somewhere in there)

just check the plug make sure it's not too lean because your symptoms overall sound like a lack of fuel.

if you can post a picture of the plug on the thread that would help the diagnosis and prognosis too..... just trying to help not step on your toes but i like to help people out and i'm interested now to see where the problems at

Isn't that the idle adjustment screw, which is just an adjustable stop for the slide? If he screws that one in all the way, then back out 1-1/2 turns, his slide will be held open about 1/8 throttle.

The screw your thinking of is underneath the front of the FCR carb, accessed through a hole in the float bowl, unless it's an '06 or newer, where the hole is plugged and you have to remove the float bowl to adjust it (unless you remove the "plug")

[Thumper1220]

:eek2: just checked my quad...now i know where the idle and idle air screws are at! :rolleyes: quite different than the ones i have seen before :eek2: thanks for correcting me on that i am used to the mikuni tm flatslides where the air screw is on the back near the intake passage.... i'm beginning to miss my 2 stroke at times

[daddio]

Originally posted by Thumper1220
... i'm beginning to miss my 2 stroke at times [/B]

Me 2

[Gommer450r]

Originally posted by daddio
Isn't that the idle adjustment screw, which is just an adjustable stop for the slide? If he screws that one in all the way, then back out 1-1/2 turns, his slide will be held open about 1/8 throttle.

The screw your thinking of is underneath the front of the FCR carb, accessed through a hole in the float bowl, unless it's an '06 or newer, where the hole is plugged and you have to remove the float bowl to adjust it (unless you remove the "plug")

if u dont have that black plug in for your mixture screw what would that doo?

[daddio]

Originally posted by Gommer450r
if u dont have that black plug in for your mixture screw what would that doo?

allow you to adjust the fuel mixture without taking the float bowl off. The plug has nothing to do with how it runs