I have an 05 V2 650 that from almost day one ran rich. I purchased it new. Synchronized the carberators and still the rear plug is black and sooty. I have cleaned out the rear carb as best i can with carb cleaner and compressed air. So..... some questions for the more knowledgable folks:
I live in AZ at about 1800 ft ASL What main jet size should I have?
In the case maybe a weak plug what alternatives to NGK CR9E is recommended.
I can only see idle mix adjustment and a single synchroize adjustment between carbs. Is there a Low Speed / High Speed sychronize adjustment like my BMW motorcycle? Did I miss it?

I really can't seem to find why my rear cyclinder fouls. Compression perfectly matches the front and it's pretty clean running after half throttle, just no low speed.

Help is appreciated.

Thanks,
Alan

 

Check the choke (not shutting clear off), float level (set too high) and the idle mixture (make it leaner if the cylinder is to rich at idle). Going to a hotter temp range plug will only mask the problem, not cure it.

 

Thanks,
Would choke effect only rear carb? I was told that the chock only choked the front carb is that not true? Doesn't make sense but that is what my Arctic Cat wrench told me.
I had the floats and needle out to clean the circuit. Looks like to check level would tough on this carb. I resisted tweaking float it to lower the fuel level because it would just be a guess on my part. I'm almost to that point though. While the bike is running I can turn the idle mix screw all the way in to seat and it does not effect the idle one bit. That tells me I'm pouring in fuel from somewhere.
The plug quesiton was not to go hotter, just for a better plug in a platinum or Iridium.

I appreciate guidence.

Alan

 

Your guy is right, the choke (actually an enrichener, no choke butterfly) is only on the front carb. It is something the accountants thinks saves money, and of course makes the engine harder to start. That leaves you with less things to check. If the idle screw is all the way in and the rear cylinder doesn't quit firing then either the float is set too high (yes it can be checked and set fairly easily), the carb is assembled wrong or missing pieces or the carb body has a crack somewhere and is bleeding fuel into the motor.

 

You have an adjustment screw on each carb try adjusting it out some to lean out the rear carb. It only adjusts the idle circuit but that could be your problem.

 

I am not the sharpest knife in the box, but I do know that some people have one cylinder with a different size jet in then the other, I have no idea why though. [img]i/expressions/face-icon-small-shocked.gif[/img]

 

Spent another couple hours on the 650 last night. I rechecked synchronization, lowered the float llevel about .030" and cleaned all the ports with carb cleaner and compressed air. I made sure the choke was not engaged then started the bike. Same thing. Rear cyclinder is loading up. While idleing I can screw the idle adjustment screw all the way in to stop and the quads idle does not change. If I do that to the front carb it stalls the motor. I even took the idle screw out while it was idleing and it made little difference. I was pulling a vacuum through the idle screw hole but for some reason it's getting enough fuel from somewhere to accomodate a such a vacuum leak.
When I adjusted the float I bent the float tab .010" (Measured with calipers) and guessed effect at float center to be around 2.5 or 3x that. I guess I can drop it even more, maybe another .050 at the floats. How does one measure the actual float level on one of these carbs? And what should the level be? Anyone know?

Thanks,
Alan

 

PS. My rear main is a 122. I have not looked at the front.

Alan

 

Did you adjust the idle circuit screw? This is not the idle screw, this screw is located at the bottom of the carb, hidden in a round tube and its hard to get to. This can adjust your air flow from idle to 1/3 throttle.

 

Yes I adjusted the idle adjustment screw multiple times. I even took it to the extremes of fully seated to fully removed while the Quad was idling and it made no difference. I cannot find where the additional fuel in the rear idle mix is coming from. The spark plug remains black and loaded up after idling while the front stays pretty nicely tan.
I wish it were lean in the back so I could look for a vacuum leak.
I don't know what to do besides lower the float bowl fuel level more. Apparently others are not having the same issue. It runs nice under the main. So that seems good.
I guess I could check the slide for sticking. When I synchronize the carbs at idle they are out of synch by about 1/2 inch of Hg. So maybe my rear slide is remaining a just open enough to pull some fuel through the main?

Alan