FCR upgrade for 400EX help

[aviator4]

Hi all,

I got my hands on FCR carb for my 400EX. I've been told that it's the right carb.

Numbers on the carb are: 5TG7 10TA26

Is this the right carb? If so, what all will I need to get to put this on my 400?

Intake boot?
Air filter box boot?
Cable?

Thanks guys!

[aviator4]

Okay, well I guess I will start answering some of my own questions since no one else here has jumped in.

I went ahead and started installing this carb after I found out that it IS the correct carb for this upgrade. This is the carb from a YFZ, according someone who is "in the know".

So far, I've installed the carb on the intake boot. It's tighter than the stock carb, but it will fit. You have to remove the stock hose clamp on the boot before it will go on, Then use an aftermarket hose clamp to tighten it down. Obviously, the stock fuel line isn't going to work either, so I replaced it with a longer piece of 5/16 fuel injection hose and re-routed over the driver side of the carb. Worked like a champ once I realized there was practically no gas in the tank and I move the fuel lever to reserve!

This carb came with a 160 main jet. It's running rich right now (backfiring flames on decelaration, black smoke on acceleration).

There may also be somewhat of a space issue. the bottom of the bowl is VERY close to the starter and will probably rattle against it when it's running. I won't know for sure until I get the intake put back on though.

Also, the gas tank will definatley touch the top of the carb as well, so it will neet to be spaced up slightly. I had to re-route the vent lines. They were criss-crossing over the top of the carb initially, but now they run down each side.

I know that I am also going to need another throttle cable. This has been addressed on the forum allready. However, the stock cable will work to get everything initially set up. Then a can tear back into it when I get the right cable.

I've also noticed the same "off-idle lag" that has been mentioned here and will be ordering the replacement accelerator pump from Sparks to take care of that issue.

So far so good. No special tools needed, no major problems. Definatley worth the time and money.

[H_W]

You will love the FCR carb. It made a big difference on my 400. I ordered mine from C & D Racing, it came with the throttle cable and it was pre-jetted for my mods, so I can't really tell you what all you need to get it working.

[aviator4]

I guess the most serious problem I've run into so far was when I put my airbox back on and realized that the boot wasn't gong to reach the carb. There's about a one inch gap there.

Did you have this prob?

[H_W]

No, I did not have any problems. I just put it on and everything fit perfectly. Besides the top of the carb rubbing the gas tank a little.

[aviator4]

Any chance I could get you to post a pic of the setup?

[crandles]

Hey I think I talked to you by the dyno labor day weekend. What kind of hp did you come up with a full shot? The FCR is a good choice for your carb. The problem with the yfz one is it does not have a removable rear bell. The 39FCR kit for the 400ex has a removable bell on the filter side. So it comes set up with a 2 inch to make up for the length you need.

[aviator4]

It ended up with 45 horse with the 15 shot.

I finally managed to get the carb spacing problem resolved. I had have my brother make an extension for the boot, but it went on no problem and works perfectly. Inner diameter was paramount.

[crandles]

So did you get the jetting all down?

[aviator4]

Yeah, we were actually playing with the pressure delivery system from the Nitrous kit. We finally got it right.

It's set to run a little rich when the nitrous kicks in, but thats a safety measure. I'd rather be rich than lean.

Of course, now that I've put this FCR carb on, it's going to have to be re-calibrated.... we're starting from scratch again.

I won't mess with the nitrous intil I can get it on the dyno and get the gas analyzer hooked up. I'm not taking any chances.

Believe it or not, I was actually walking away from my brother on his DS650. my other friend that was there didn't stand a chance on his 400 so he brought his Raptor out.... I smoked it too. I was even staying up with a lightly modded banshee. I am very happy with the nitrous. I may only have that kind of horsepower for 8 seconds at a time, but thats enough to humble the rest of 'em!