2002 YZ 125 Carb Help

[Goon Rides]

Hey guys... so I have a problem... I took the bike at Cal City, broke it in, and while I was doing so, the bike was bogging in first gear (Yes, first gear). Also it doesn't idle at all. I have to keep blipping it otherwise it'll stall. So I adjusted the screw circled in image 1. Well I was listening to the sound of the of the bike, yet the rpm's weren't increasing, and it was still stalling. So then, I unscrewed the screw in image 2, well I found out that it was fully twisted to the right. So then, I twisted it to the left, still nothing; it was still stalling... where's the idle screw? I am sure that the screw in image 1 is for the air/fuel mixture screw, and the screw in image 2 is the idle screw, just broken? I don't know, any and every help would be appreciated.

[EmpireofDerp]

Hey guys... so I have a problem... I took the bike at Cal City, broke it in, and while I was doing so, the bike was bogging in first gear (Yes, first gear). Also it doesn't idle at all. I have to keep blipping it otherwise it'll stall. So I adjusted the screw circled in image 1. Well I was listening to the sound of the of the bike, yet the rpm's weren't increasing, and it was still stalling. So then, I unscrewed the screw in image 2, well I found out that it was fully twisted to the right. So then, I twisted it to the left, still nothing; it was still stalling... where's the idle screw? I am sure that the screw in image 1 is for the air/fuel mixture screw, and the screw in image 2 is the idle screw, just broken? I don't know, any and every help would be appreciated.

http://users.conwaycorp.net/virtus/page2/speed/jetting.htm

[mlatour]

You are correct,

# 1 is the air screw, turning it counter clock wise, more air is added to the low speed circuit, leaning the mixture

#2 is the idle speed screw, you loosen the outer lock nut before turning the inner screw, clockwise raises the rpms

 

By the way your air inlet boot clamp looks like a pretzel and weakened near the screw flange.

For the relatively low cost of that part you should preventatively replace it,

in the event it fails, debris ingested could end up costing your an engine refurb.

 

Edited October 7, 2018 by mlatour

[ar2stroke]

16 hours ago, mlatour said:

You are correct,

# 1 is the air screw, turning it counter clock wise, more air is added to the low speed circuit, leaning the mixture

#2 is the idle speed screw, you loosen the outer lock nut before turning the inner screw, clockwise raises the rpms

 

By the way your air inlet boot clamp looks like a pretzel and weakened near the screw flange.

For the relatively low cost of that part you should preventatively replace it,

in the event it fails, debris ingested could end up costing your an engine refurb.

 

 

I agree, would replace both of them clamps on the Air boot and the intake manifold. Especially on the air boot to the air box (dirt/debris) will equal smoked engine. 

[Goon Rides]

On 10/6/2018 at 8:59 PM, mlatour said:

You are correct,

# 1 is the air screw, turning it counter clock wise, more air is added to the low speed circuit, leaning the mixture

#2 is the idle speed screw, you loosen the outer lock nut before turning the inner screw, clockwise raises the rpms

 

By the way your air inlet boot clamp looks like a pretzel and weakened near the screw flange.

For the relatively low cost of that part you should preventatively replace it,

in the event it fails, debris ingested could end up costing your an engine refurb.

 

For #1, I don't know how to adjust it, probably ruined my carb. It didn't make any noise (No raise in RPMs)

For #2, I did loosen the lock nut, then turned the screw clockwise, no raise in RPMs... then turned it counter clockwise, still no increase or decrease in the rpms.

[EmpireofDerp]

For #1, I don't know how to adjust it, probably ruined my carb. It didn't make any noise (No raise in RPMs)
For #2, I did loosen the lock nut, then turned the screw clockwise, no raise in RPMs... then turned it counter clockwise, still no increase or decrease in the rpms.

The link i posted is the best guide ever written to carb set up. Read it.

[Goon Rides]

3 hours ago, HevyRotashunz said:

11 hours ago, Goon Rides said:

For #1, I don't know how to adjust it, probably ruined my carb. It didn't make any noise (No raise in RPMs)
For #2, I did loosen the lock nut, then turned the screw clockwise, no raise in RPMs... then turned it counter clockwise, still no increase or decrease in the rpms.

The link i posted is the best guide ever written to carb set up. Read it.

I read it... very helpful. But here's the thing, I think my screw is broken or something, because nothing is happening.

[mlatour]

If you have a high float level, air leak, way too small or large pilot jet etc.

the limited adjustment range of the air screw might not make much difference.

Edited October 8, 2018 by mlatour

[Goon Rides]

1 hour ago, mlatour said:

If you have a high float level, air leak, way too small or large pilot jet etc.

the limited adjustment range of the air screw might make much difference.

#30 Pilot Jet

[TommyCrown]

30 Pilot is small..  ok in certain situations but not a neutral place to start.

I now run 37.5 and it is spot on after trying many others up and down...

Needle clip position 2.

MX ridden hard. Std main. MOTUL 800 32:1 98 Octane mix fuel.

 

 

[Motox367]

Buy 4-5 numbers larger pilot jets . Keep going up untill you can whack throttle fast as can and doesn't bog. Thats easy way to dial in pilot jet? do that and it will rip. Then can see if main is ok. But your air screw at 1-1/2- 2 turns out from fully seated and leave that alone 

[Goon Rides]

Carbs are hella complicated. I will look into it though, thanks.

17 hours ago, Motox367 said:

Buy 4-5 numbers larger pilot jets . Keep going up untill you can whack throttle fast as can and doesn't bog. Thats easy way to dial in pilot jet? do that and it will rip. Then can see if main is ok. But your air screw at 1-1/2- 2 turns out from fully seated and leave that alone 

 

17 hours ago, TommyCrown said:

30 Pilot is small..  ok in certain situations but not a neutral place to start.

I now run 37.5 and it is spot on after trying many others up and down...

Needle clip position 2.

MX ridden hard. Std main. MOTUL 800 32:1 98 Octane mix fuel.

 

 

Clip position is at the 3rd level.

[mlatour]

10 hours ago, Goon Rides said:

Carbs are hella complicated.

Your current one is about as simple as it gets.

If you think this one is complicated, be sure to never buy a pre-fuel injection 4-stroke MX bike equipped with the Keihin FCR carburetor (most of them are)

Edited October 10, 2018 by mlatour

[Goon Rides]

On 10/9/2018 at 6:17 PM, mlatour said:

Your current one is about as simple as it gets.

If you think this one is complicated, be sure to never buy a pre-fuel injection 4-stroke MX bike equipped with the Keihin FCR carburetor (most of them are)

I know that I don't have the TMX because I bought two chokes (mine is broken), for the TMX, and they both didn't fit.

[Goon Rides]

I don't think this is normal... in first gear it bogs when releasing the clutch with gas, I'd have to go full throttle (it would kill the clutch plates tho) to make this thing move, and when I drop the RPMs (not completely) it will bog again, regain power, and go super duper fast!

[Motox367]

37 minutes ago, Goon Rides said:

I don't think this is normal... in first gear it bogs when releasing the clutch with gas, I'd have to go full throttle (it would kill the clutch plates tho) to make this thing move, and when I drop the RPMs (not completely) it will bog again, regain power, and go super duper fast!

Told you keep going up on pilot jet until you can whack throttle fast as can without it bogging.  Then will be much better i bet ?

[Goon Rides]

3 minutes ago, Motox367 said:

Told you keep going up on pilot jet until you can whack throttle fast as can without it bogging.  Then will be much better i bet ?

Alright will order some of those. And for the air screw turn it 1.5-2 turns counter clock or clock? When it's turned fully clock is it seated or opened? When it's fully turned counterclock? Also for the idle I just listen correct>

[Motox367]

 

Alright will order some of those. And for the air screw turn it 1.5-2 turns counter clock or clock? When it's turned fully clock is it seated or opened? When it's fully turned counterclock? Also for the idle I just listen correct>

Put air screw at 1.5 -2 turns out from seated and leave it get few numbers bigger pilots and few numbers lower on main than stock. Sounds like your main is ok but pilot to small. Put needle clip 2nd notch down from top. Then report back ? 

Edited October 15, 2018 by Motox367

[Goon Rides]

Just now, Motox367 said:

Put air screw at 1.5 -2 turns out from seated and leave it get few numbers bigger and few numbers lower on main than stock. Sounds like your main is ok but pilot to small. Put needle clip 2nd notch down from top. Then report back ? 

FMF recommends 3rd level and 30 pilot, I agree with you on the jet, but why change the clip level? (What does it do)

[Jonesy79]

Now, it's time to work on the needle. Mark the throttle grip at 1/4 and 3/4 openings. Ride the bike between these two marks. If the bike bogs for a second before responding to throttle, lower the clip (raising the needle) a notch at a time until the engine picks up smoothly. If the bike sputters or sounds rough when giving it throttle, raise the clip (lowering the needle) until it runs cleanly. There isn't really any way to test the needle other than by feel, but it's usually quite obvious when it's right or wrong.

 

you obviously didn’t read the helpful articl that was posted