carburetted M900 rough running '96.

[CX500]

Hoping someone might recognize this symptom:
Rough running, sputtering, and coughing at steady throttle.  Give the throttle a twist and it runs great -- lifts the front wheel.  Idle is OK, maybe a little rough. 
Sounds like a carb issue to me - maybe a plugged jet before the needle jets take over, but it also smells very rich after running rough.  This made me wonder about electrical.  I am going to change plugs tomorrow.  Try to check one thing at a time.
Any insight would be greatly appreciated.

MarcuSS

[ducpainter]

Hoping someone might recognize this symptom:
Rough running, sputtering, and coughing at steady throttle.  Give the throttle a twist and it runs great -- lifts the front wheel.  Idle is OK, maybe a little rough. 
Sounds like a carb issue to me - maybe a plugged jet before the needle jets take over, but it also smells very rich after running rough.  This made me wonder about electrical.  I am going to change plugs tomorrow.  Try to check one thing at a time.
Any insight would be greatly appreciated.

MarcuSS

Replace the needle jets/emulsion tubes.

I have the same bike.

[beethoven]

+1 Needle jets. They get worn and let fuel through at low-mid revs causing roughness and richness. I have 97 M900 and have just done them at 45000 km. Fuel consumption has improved about 15%. The mechanic photographed the tube and it had a definite oval shape rather than circular.

[CX500]

Thanks for the replies.  This is exactly what I was thinking, especially at 35,000 miles.
Now, do I do some work on these carbs, or go for the flat-slides I always wanted.  Hmmmm...




MarcuSS

[ducpainter]

Thanks for the replies.  This is exactly what I was thinking, especially at 35,000 miles.
Now, do I do some work on these carbs, or go for the flat-slides I always wanted.  Hmmmm...




MarcuSS

needle jets will set you back about $100...

Flatslides will be considerably more.

How flush are you?