2003 RX-1 Mountain carb advice

[jhanratt]

I recently purchased a low km 2003 RX-1 mountain. It appears to be bone stock and has 1,600 kilometers. I went through the carbs as a precaution and found two float bowl mounting screws were a bit chewed (outside screws) and all four float bowl screws (inside) have been over torqued until the screw heads bent. Obviously somebody has been in there before me. I have replacements from Yamaha on my bench now and I will replace them all when I go back into the carbs.

So the machine starts well, idles well, and pulls HARD! but it leaves carbon around the exhaust tips and on the tunnel extension. The exhaust also burns my eyes when I idle it in the shop. It does not smell of burning oil more like a four stroke with the choke left on. I would describe it as rich exhaust. In my opinion a four stroke should idle for a long time in a shop before you even notice the exhaust. My quads can idle a long time inside the shop without bothering me.

In addition I just built a tunnel mounted pack box and I formed exhaust deflectors out of aluminum to prevent hot exhaust from melting the plastic. After one ride they worked well but the checker plate aluminum is coated in brown and black carbon.

I think I need to lean it out a little bit but I'm intimidated by the process and have never adjusted carbs beyond idle and simple synchronization of slides. I do have extensive experience dis-assembling, cleaning, and re-assembling them. I just always mark the adjustment screws then count turns to full close and re-assemble in the same position. I also have extensive sledding experience and extensive mechanical experience.

Can anyone give me any simple advice on this or should I just live with it because it does run good. It just blows a lot of carbon and soot???

Further details:

The carbs were spotless inside. The float bowls were clean. The jets were clear.
I have two fuel filters on my bench along with the carb screws for install soon.
The previous owner reported 1,000 km since last oil change. (It was a bit dirty)
I changed the engine oil and filter and I have put about 300 km on it.
It does not appear to burn oil.
I cleaned the clutch sheaves with acetone and steel wool.
I lubed the skid and steering.
I checked the chain case oil and it's overfilled. I think it's ok because there is lots of room in the chain case.
I have a pdf service manual for the machine.

Thank you in advance for your sage advice.

JH

 

[jhanratt]

Pics

 

[maim]

it is probably jetted for a higher elevation. you should confirm what the jets are and if they are correct for your riding elevation.

my 05 rx left soot on the garage door and tail extension and the jetting has not changed in it since i bought it. it runs great and the plugs are a good colour so i leave it alone.

 

[jhanratt]

Thank you.
I’ll check my jets when I install the new screws. I didn’t look at the size when I was in there. I only confirmed they were clean.

 

[Al Bundy]

I recently purchased a low km 2003 RX-1 mountain. It appears to be bone stock and has 1,600 kilometers. I went through the carbs as a precaution and found two float bowl mounting screws were a bit chewed (outside screws) and all four float bowl screws (inside) have been over torqued until the screw heads bent. Obviously somebody has been in there before me. I have replacements from Yamaha on my bench now and I will replace them all when I go back into the carbs.

So the machine starts well, idles well, and pulls HARD! but it leaves carbon around the exhaust tips and on the tunnel extension. The exhaust also burns my eyes when I idle it in the shop. It does not smell of burning oil more like a four stroke with the choke left on. I would describe it as rich exhaust. In my opinion a four stroke should idle for a long time in a shop before you even notice the exhaust. My quads can idle a long time inside the shop without bothering me.

In addition I just built a tunnel mounted pack box and I formed exhaust deflectors out of aluminum to prevent hot exhaust from melting the plastic. After one ride they worked well but the checker plate aluminum is coated in brown and black carbon.

I think I need to lean it out a little bit but I'm intimidated by the process and have never adjusted carbs beyond idle and simple synchronization of slides. I do have extensive experience dis-assembling, cleaning, and re-assembling them. I just always mark the adjustment screws then count turns to full close and re-assemble in the same position. I also have extensive sledding experience and extensive mechanical experience.

Can anyone give me any simple advice on this or should I just live with it because it does run good. It just blows a lot of carbon and soot???

Further details:

The carbs were spotless inside. The float bowls were clean. The jets were clear.
I have two fuel filters on my bench along with the carb screws for install soon.
The previous owner reported 1,000 km since last oil change. (It was a bit dirty)
I changed the engine oil and filter and I have put about 300 km on it.
It does not appear to burn oil.
I cleaned the clutch sheaves with acetone and steel wool.
I lubed the skid and steering.
I checked the chain case oil and it's overfilled. I think it's ok because there is lots of room in the chain case.
I have a pdf service manual for the machine.

Thank you in advance for your sage advice.

JH

Mine does the same thing. Runs great but will spit some black out the pipes. I use a little seafoam every fuel fill up. I'd say don't worry too much about it, but make sure your riding buddies don't park too close behind you before start up.

 

[givemeaboost]

To save yourself some future problems with those screws I would go to a hardware store and get some stainless hex screws so you can take them out with an allen wrench.


Ken............

 

[jhanratt]

Update,

I pulled the carbs out again and replaced all four of the screws that hold the floats in the carb. I can't believe how tighly they were installed. All four had been bent and all four had a bevel on the back side from being over tightened against the little round bars allows the float to pivot and that that holds the floats. I cant believe they didn't strip the threads out of the carbs! While I was inside I checked the jets and compared against the manual. As I recall the jets in my RX-1 are 132.5 And as I recall the stock jet for sea level was 137.5 The manual calls for 135 at the elevation I live at and sometimes ride and 132.5 for the elevation that I most often ride at.

I have not checked the pilot screws but I am considering tightening them down to 3/4 from what I understand is stock setting at 2 turns. Would this even help at all??? I'm guessing pilot screws are more of an idle and maybe mid range thing?

What about changing the clip setting on the needles?

(I'm good with cleaning carbs but don't understand tuning at all!)

Or maybe I'll just have to live with the carbon spray from the exhaust.

Thank you all.

J

 

[Shattered]

Update,

I pulled the carbs out again and replaced all four of the screws that hold the floats in the carb. I can't believe how tighly they were installed. All four had been bent and all four had a bevel on the back side from being over tightened against the little round bars allows the float to pivot and that that holds the floats. I cant believe they didn't strip the threads out of the carbs! While I was inside I checked the jets and compared against the manual. As I recall the jets in my RX-1 are 132.5 And as I recall the stock jet for sea level was 137.5 The manual calls for 135 at the elevation I live at and sometimes ride and 132.5 for the elevation that I most often ride at.

I have not checked the pilot screws but I am considering tightening them down to 3/4 from what I understand is stock setting at 2 turns. Would this even help at all??? I'm guessing pilot screws are more of an idle and maybe mid range thing?

What about changing the clip setting on the needles?

(I'm good with cleaning carbs but don't understand tuning at all!)

Or maybe I'll just have to live with the carbon spray from the exhaust.

Thank you all.

J

Those bent screws on the floats come that way out of the factory. I'm the first one to open up the carbs on my RX, and they were that way as well. I suspect they are that way on purpose in order to keep them from backing out.

 

[Kill_basser]

my tips are the same way and running fine

 

[74Nitro]

Put a catalytic converter on it.