FCR Idle issues.

[671M900]

Ever since i got the bike back together, I've had issues with the FCR's and idle. She starts great with two twists of the throttle, and idles where I set her (1150). After riding for maybe 10 minutes, and the bikes good and warm, she'll idle at 2000, maybe 2500. I experimented with releasing the clutch in gear slightly to see if she would get back down to 1100. She goes back up to 2500 when I pull in the clutch.

Then a little after, maybe the next stoplight, she'll idle at 1100, but drop very slowly until it dies. But a quick twist of the throttle brings her back up for a bit.

any ideas? Vacuum leak? I'm also using K&N Pod filters if that's causing the problem.

[Speeddog]

What year and model of Monster is in question?

Did you thoroughly clean the carbs, especially the idle jets?

If the idle circuit is lean, the hot idle can go up enough that it gets into the ignition advance curve, then it really goes up.

[Howie]

Also check carb synch.

[671M900]

What year and model of Monster is in question?

Did you thoroughly clean the carbs, especially the idle jets?

If the idle circuit is lean, the hot idle can go up enough that it gets into the ignition advance curve, then it really goes up.

99 m900. Fcr's were installed brand spanking new from Chris at ca cycleworks. How should I set the idle with fcr's? Fully warm it up and then bring it down slightly? I'm assuming I set it to high at cold idle, the damn idle screw is nearly all the way open.

[Speeddog]

First check that the synch is good, as howie suggested.

Then, yes, set the idle with the engine fully warmed up.

AFAIK, Chris confirms that the basic setup is good on each set of carbs before they go out the door.
They're not necessarily all set for every possible combo of mods....

[brad black]

the damn idle screw is nearly all the way open.

to which idle screw are you referring?

[671M900]

to which idle screw are you referring?

The one next to the throttle linkage? The one with the knob on the flexible shaft? I hope that's correct, seemed like an idle adjuster since it raised both slides.

[brad black]

i usually wind the idle screw in one turn when starting them, then wind it out again as it warms up.  i'd say it's lean and hanging up on the spark advance, then dying if it loses the spark advance.  i had one do that last week after i'd gone down from 60 to 52 pilots.  unlike the last one i did, it really liked 60 pilots (also had pods).  idle mixture screws were the normal 3/4 turns out, slow air screws 1 1/2.

so go over the idle settings and then look for vac leaks.  block the hoses coming off the manifolds first to see if it's either of them.

[junior varsity]

i do the same wind-in, wind-out procedure with that "fast" idle screw on the flexible tube.

[671M900]

i usually wind the idle screw in one turn when starting them, then wind it out again as it warms up.  i'd say it's lean and hanging up on the spark advance, then dying if it loses the spark advance.  i had one do that last week after i'd gone down from 60 to 52 pilots.  unlike the last one i did, it really liked 60 pilots (also had pods).  idle mixture screws were the normal 3/4 turns out, slow air screws 1 1/2.

so go over the idle settings and then look for vac leaks.  block the hoses coming off the manifolds first to see if it's either of them.

Thanks for the help! horizontal manifold is already capped off. I'm using the vertical manifold port to work the fuel pump. I'll check the mix screws, 3/4 of a turn out only?

[junior varsity]

how did you cap it off? Just a vacuum cap or with a crush washer and small bolt?

[671M900]

how did you cap it off? Just a vacuum cap or with a crush washer and small bolt?

Used a vacuum cap. Nice and tight fit. Should I change it to a flanged bolt and crush washer?

[junior varsity]

I dunno - I used a crush washer and a shaved down bolt (so it didn't protrude into the air-path inside the manifold). I would think the vacuum would "suck" the vacuum cap into a seal on the nipple fitting, just not sure.

[akmnstr]

I had the same problem for years.  Never did figure it out.  I looked for vacuum leaks. Nothing.  Change low speed jets.  Made it worse.  I found the adjustment that worked best and left it.  It was very frustrating.  Unless your carbs are much different from mine you can't sync them really.  I did the drill bit method the Chris recommends and found they were close anyway.  You might try calling Chris and see if this has been a common problem for which there is a standard solution.