Junk FCR?

[nakomis0]

When I first got my FCR it took me a month to find out it had somesort of leak. The plug was always white no matter what jet was in it.

They gave me a new one. It worked great. My plug were always brown, sometimes black, it was slightly rich. Even in the winter. (i think)

Than last weekend I go riding, my plug is white and I notice some sputtering in the low to mid range.

I have no jets, So I raise the needle, Didn't help, and the plug was still white. (Airfilter was oiled well)

I was thinking it was the pilot, but thats a 52 should be ok...

The main is a 168...

needle is 3rd notch...

I guess I'm going to try a 54 pilot, and 170 (172) whatever the next size main. Hope that works.

Anyways I don't get it, the temp is warmer and I'm running lean?

I hope this dang carb don't have a leak. Has anyone else had a problem with FCRs leaking and not jetting right. (i'm talking air leak)

Is sucks because I have no way to ride in my area and I'm off to Silver Lake next Weekend. So its Do or Die, now or doing 'field jetting' while I could be riding at the dunes.:(

Any comments or suggestions are welcome...:square

[nakomis0]

How about air, and fuel screw? Does this FCR have it, where is it, and what should it be set at?

I have the carb apart sitting at my desk.

[JustRace]

Not to be a smart arse, but have you checked to see that there is a leak in some other place. Like the boot on the manifold or in the intake to the carb? Have fun at Silver Lake, i'm yet to make it up there this year.

[powerslider]

Try some race fuel mixed with pump premium, they change the fuel blend in the spring which may be why your plug turned white. It may not be lean, you may actually be rich causing the sputtering, just a thought......

[Leo]

check the intake between the carb + head very carefully for leaks / cracks / pinholes..

Leo

[CBRSLIDER]

Like the others recommended. Check the manifold boot between the carb and cylinder. I was going thru the same thing with the stock carb and found there was a separation starting on the boot. The area where the rubber is glued to the manifold plate was cracking. I also found that the seals around the intake boot and the air box were shot. I sealed everything and it changed the jetting. I had tried everything. I even went back to stock(no pipe, hole in air box lid, and choke). Until I sealed up these areas, nothing helped.

Just a suggestion.

Ray

[nakomis0]

1 thing I did forget to mention was I added Lead to my gas. It was very little 1/2 ounce for 5 gallons.

.Going with what Powerslider said, Can you be running rich and have a white plug?

I'm going to the Magics Racing tomarrow to talk with the guy that built a few other bikes like mine.

Thanks for the replies...

And I will check all the boots and other areas.

[NVR2L8]

I've had an 39mm FCR on my 400EX for a year now...had it installed at the same time I did the 416cc and XR400 cam mods. I have to say that the FCR has been the best aftermarket component I've installed so far, and it's worked fine and trouble free...by far a much better carb than the stock unit in my opinion. At any rate, I've never had my FCR "leak" due to some sort of problem with it, and your problem sounds more like an intake leak somewhere.

I agree with those who mentioned checking the carb insulator...the adapter between the carb and head. While mine didn't have any cracks or leaks, it was slightly warped and I believe it was sucking a little air past the sealing o-ring. So check your insulator for any obvious problems, and set it on a piece of glass or any other ultra smooth surface to check the flatness. If it seems okay, you should at least replace the o-ring. FYI...I think the higher operating temps of build motors tend to warp and/or break down this part. Just my opinion...

Yes, there is both a fuel and air screw on the FCR, but both are a real pain to get to without pulling the carb. The fuel screw is in the front of the carb in a recessed hole. Pull the carb and set it to 2 1/2 turns out after lightly seating it. The air screw is behind the horn on the airbox side of the carb....you have to remove the horn to access the screw. I've never changed the setting of my air screw as it seemed fine. You might try calling Sudco at 323-728-5407 and ask them what the general setting should be.

Lastly, although you're running a little higher displacement than I am, I think you're jetting is really close. On my 416 I have a 52 pilot, needle on the 3rd groove, with a 165 main. I can tell you though, that I couldn't get a good plug reading on normal 92 octane pump gas due to the clean air additives in the gas. If the gas in your area is also full of additives, then you'll probably continue to see a white plug. In order to get my jetting right while also getting a nice light brown plug, I had to start using a blend of race and premium gas. For the most part, I now always run a mixture of 3:2 (3 gals of 92 octane to 2 gals of 108 leaded VP race gas), and haven't had any jetting or detonation problems.