Slant FCR idle too high

I just got done installing a very clean FCR slant body on my '08 SM. My bike has a full RS-2 and the 3x3 mod. The jetting is:

165 main

200 maj

100 paj

45 pilot

EMN needle on the 3rd clip

stock fuel screw 2 out

Taffy Mod with duration less than a second.


All the correct Sudco parts for it to fit

I installed new Motion Pro cables and it has play in the throttle.

I put the nipple for the vacuum line on the motor.

The idle adjustment is backed off to where the screw doesn't even hit the throttle wheel.

It's idling very high, and I've checked for air leaks, and there doesn't seem to be any.

If I rev it up in idle I see some flames, and a few seconds after I shut it off I get a pop from the exhaust.

Any ideas on what's going on?

I live at 800ft.

check the slide plate.its probably broken.

Thanks for the reply Eddie. I had the thing totally apart before I put it on to make sure everything looked ok, and the slide plate looked like it had been replaced recently. There were no wear marks on it at all. Could it have broken when I started it? Any other things to look for?

or its upside down or the carb body is worn out.

its also possible the slide height adjuster (nut with screw in the center on the the throttle shaft under the carb cap) has been touched.

I know it's not upside down, but I did take off the slide screw so I could pull the slide out. Is the height adjustable? That sounds like something I could fix by spinning the carb instead of taking it all the way off.

you can do it just taking the cap off.

start the bike,loosen the lock nut and and turn the screw till it just stops idleing.

lock it down and then set the idle speed normally.

Shredman - How sure are you that the slide plate is not up side down? The adjustment Eddie talks about might help if it is way off, but mostly that is to balance multiple carbs. Also the rubber seal between the roller slide and the slide plate could be upside down, damaged or missing.

Hey Noble,

I know it's in right because the point goes down, and I put the seal in the right way. I've worked on these carbs a bunch, and I'm pretty confident that it got put back together right, which is why it's so strange to me.

Edit: The point isn't down, I just remembered it wrong.

hold up,the point doesnt go down.the square end does.that is your issue.

Does the slant style have the hole in the plate? I don't remember, but if it does, the hole is down, and then the point is up. I know I would have put the hole down.

this is the proper direction of the plate.


That's the same for the MX and the slant body, correct? If so, then I have it in right.

its the same on all fcr.

Shredman - You can set the slide height with the carb off the bike. About .020 gap under the slide should put the idle speed in the ball park. If not, air is entering from some unknown, uncontrolled source.

I had a chance to play with it some yesterday. When I loosened that locknut and turned the little screw, it didn't lower the slide. Will I only notice a difference if the bike is running? Will it run with the top cap off? I noticed that the hanger that pulls the slide up is screwed onto the piece with the locknut and little screw. If I loosed up that Phillips screw just a tad from full lockdown the slide will drop some. Could that lever be tweaked a bit? How much of the idle adjustment screw should be showing, meaning how far should it be up? Mine is only up a few threads, which leads me to think it might be something other than the slide being too high. I hate to do it, but I guess I'll have to take it off again and measure the slide height and go from there. Any other places it could be leaking air? There's a hole right below the choke knob on the body, what is it for? And what should I use to check for leaks? I used WD-40 last time. Thanks for all the help!

i explained how to do it.

i will run just fine with out the cap.

The technique I use is to loosen the lock nut, back out the screw several turns. Turn the lock nut in lightly so it goes in as far as it will go. Then back out the lock nut 2 turns. Tighten the screw lightly, then tighten the lock nut. That should put it in the center of the adjustment range. It is not real critical. The phillips head screw should have no affect on slide height. That is to set the end clearance (latteral movement) of the operating shaft.

WD40 works fine for checking leaks. The hole you ask about is probably the one used to mount the CE.

Thanks for the info Noble. I tried adjusting the screw and it did nothing. I've figured out it's not the slide height because I took the slide out to replace the plate seal and put the slide back in without the holder in place and it fell to the same spot that it did with the holder in place. So, I put in a new seal, took the carb off to make sure I had no leaks of any kind, and put it back on and still have the same problem. I rode it around for a half an hour to see if it would change after warming up, and got no change. It runs great though, and seems to be jetted perfectly. The idle being high though makes it seem like there's no engine braking. I obviously can't keep riding it like that. So, I'm fresh out of ideas, anyone have anything else I can try? The jet opposite of the pilot is the starter jet, right? It's a 65, could that have anything to do with it? It starts just fine. Thanks for the help guys.

sounds like the typical worn out fcr carb body.

Thanks Eddie. When the body wears out, what part if it wears? Is it around the slide, or in the passageways? The slide seems like it's a pretty tight fit.

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