Suzuki Central Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
326 Posts
Discussion Starter #1
I've heard of some people putting an FCR carb on the Z400's in place of the oem Mikuni. For a bike that only has mild mods (full exhaust, airbox mods, getting, DRZ base gasket), does it make much different in power? OR would you need more mods like cams, headwork, big bore kit in order to notice any power increase from going to an FCR?

My YFZ450 has an FCR, and it's got brutal power....but I think that's more the motor than the carb.
 

·
Registered
Joined
·
380 Posts
Hundreds of threads and posts about this.

Best mod I did before going BBK and cams .

Power,no
Throttle response, yes
Makes it pull faster out of the corners. It gives a lot more acceleration.
 

·
Super Moderator
Joined
·
4,191 Posts
Best bang for the buck on any Z, regardless of mods. The stock carb is a serious choke point in letting the quad breathe. The vacuum diaphragm is sluggish, to say the least. Converting to a mechanical carb and adding the accelerator pump (AP) gives it the immediate punch that the stocker lacks and it would see much better airflow with your setup.
 

·
Registered
Joined
·
326 Posts
Discussion Starter #4
Where can you find a good deal on a 39mm FCR? I've searched ebay, but it seems like all the nice used ones are going for $200+ ....

I thought you used to be able to get one for a lot less......?
 

·
Super Moderator
Joined
·
3,357 Posts
They come up for sale here once in a while, might still be some in the for sale section. 125 and up seemed to be the ballpark, depending on mods.
 

·
Registered
Joined
·
326 Posts
Discussion Starter #6
For those of you who are running an FCR….what was actually involved in getting it hooked up? I've searched all kinds of threads, and it seems to range from “it bolts right on” to “here is the list of 50 things you HAVE to do to make it work right”.


I've seen some people saying you need to strip all the extra TPS stuff off of the YFZ carb to get it to fit, others say leave it. Some say you need a new throttle cable, others say that they are still using the stock Z400 cable. Some say you have to use the pull choke on the FCR, some say they were able to use the stock Z400 type choke. Some say you need airbox mods, some say you don't. .....you get what I'm saying.


So what do you actually need to make it work? If I spend $150-$200 on an FCR....I want to make sure I have everything I need to make it work.....I don't want to be dead in the water messing with parts after I have the FCR.


Any info would really be great!! Thanks
 

·
Super Moderator
Joined
·
4,191 Posts
There are many options for the thumb throttle. I used one off a honda 400ex, some keep the stock throttle and use an application-specific cable from Motion Pro. You'll need to modify (build your own) or replace your intake tube from the air box, such as the 400 ex. I was able to stretch my stock head boot, some prefer making one from automotive fuel tank hose for better clearance from the head stay. There is no vacuum on the FCRs, so you'll probably want to swap the crappy stock petcok for one from a raptor660.

Basically, there are plenty of ways to do it, you'll just have to pick one and go with it. But no, it isn't a direct bolt-on.
 

·
Registered
Joined
·
16 Posts
@iqraceworks . I suggest you search for models that come with that carb stock (that's what I did) for example : DRZ400E , WR450R , some KTM's . In my country Romania people some people don't really know the value of this carb so I managed to pick one up used for 120 bucks . I just need to order a Raptor Pet WooterWooterWooterWooter and a TRX Thumber and I think I should be good to go . :)
 

·
Registered
Joined
·
6 Posts
I just did this mod. I used a 400ex intake boot. K n N filter. Yzf thumber and throttle cable. You can cut one of the bolts off the throttle cable on the carb side n it works perfect. Good luck with jetting. I'm not quite there yet but everyone seems to be running 48 pilot n 170 main.
 

·
Registered
Joined
·
1 Posts
I just did this mod. I used a 400ex intake boot. K n N filter. Yzf thumber and throttle cable. You can cut one of the bolts off the throttle cable on the carb side n it works perfect. Good luck with jetting. I'm not quite there yet but everyone seems to be running 48 pilot n 170 main.
Is this all u had to have to do the swap
 

·
Registered
Joined
·
100 Posts
@Suzuki guy


BY ALL MEANS, do it!! I had a 400ex carb on mine for a while and got sick of tuning it bc I wasn’t willing to spend a few bucks to fix my fcr (that I got for free) up. I just installed yesterday and BY FAR the best mod you can do!

-660 raptor fuel petcock
-yfz450 throttle cable
-400ex thumber
-fcr, jets, ncvq needle
-do away with the tps
-use stock carb to head boot (I drimmelled mine, then stretch it on the carb) some use a hair dryer to make the rubber plyable
-400ex boot (cut just a hair off the first rib, the very first rib)
-mod your air box (I cut mine just a tad smaller than the ex boot, really the exact same size, the ex boot has a double lip lip, I used it to seal both sides of the air box
-I reused the same air/oil nozzle on mine, just get a small screw in c clamp and tighten it down

I’ve got a 462 with nothing stock, & that 400ex carb was starving the motor.... this thing rips through the gears and pulls harder throughout the whole range. Def wakes the motor up.

Some use a 2” gas hose for the carb to head boot, which I will have to eventually, but if your like me and have already dumped a ton of money into it, the $30 for 2’ of gas hose at a auto store, isn’t too appealing.

Good luck, any questions, just ask. Plenty of threads on this, hence why, it’s worth it
 

·
Registered
Joined
·
100 Posts
And one cool fact, the mains you’ll def have to have a place order them (Honda ordered mine and gave me a discount, they’re like 6.50 maybe, a piece) the slow/pilot jet, are like 4-5$ (Honda pilot jets are the same) they’re the same pilot jets from a Honda 400ex for the fcr (mine was a fcr39 btw, off a 2007 yfz450)

It helps when you have a buddy who has a yfz450 with tons of parts on hand
 

·
Premium Member
Joined
·
4,882 Posts
plugging off the leak jet helps
 

·
Registered
Joined
·
100 Posts
Hey Cataway, I’ve read this and read the opposite too... I have a 35 leak jet on the way, what’s the deal with blocking it off? Is it beneficial to block it off or go with a leaner jet?

I know it keeps fuel from back tracking
 

·
Super Moderator
Joined
·
3,357 Posts
I have a 35 leak jet on the way, what’s the deal with blocking it off? Is it beneficial to block it off or go with a leaner jet?
I guess you would have to experiment to find out. Some people feel that it might be rich when it squirts it in. I broke mine trying to get it out, so filled it with solder..Works great..
 

·
Administrator
Joined
·
7,772 Posts
I've never found plugging the leak jet to be necessary. The one time I tried it, the engine got blubbery on rough ground, because the pump was just going wild.

There is such a thing as too much fuel. I've seen it on the dyno. When they're perfect, you can usually still make them bog from an idle, if you're trying, but they won't bog while riding. Having enough pump is important. Too much is just as bad as not enough.

When it comes to sizing the leak jet, the bigger the engine, the less pump shot it will actually need to not bog. This is assuming that the timing is set, everything is working properly, and that the linkage is already wired solid. 480-500cc seem happy with a 55-70 leak jet. 450-470's seem happy with a 45-55. Stock bores and 434's are usually more in the 35-45 range. They vary from this, but I've found it to be a good start point.
 

·
Premium Member
Joined
·
4,882 Posts
all so easy to try...……..well kinda easy
 
1 - 17 of 17 Posts
Top