How much of an upgrade is the fcr39?

[MyKLX400]

My carb seems perfect to me, however I am always looking for that next mod.

Is the FCR that big of an improvement over the stock one?

 

[ohiodrz400sm]

Yep

[sbmon]

Seat of the pants it definitely yields more power than a full exhaust. Meaning fcr jetted correctly with stock pipe > stock carb jetted correctly and a full exhaust. Both of the above were were used with the 3x3.

 

If I were to only do one or the other, the carb is the wiser choice imo.

[30x26]

2 hours ago, MyKLX400 said:

My carb seems perfect to me, however I am always looking for that next mod.

Is the FCR that big of an improvement over the stock one?

 

coming from mikuni + jd kit is a good upgrade but nothing huge. advantage is more noticeable if your riding stile or terrain need a lot of sudden and fast openings of the throttle. for a more relaxed riding most differnence is only noticeable at high revs (were a smooth rider seldom run).  

to an already satisfied rider i would suggest it only if he finds a bargain in mint condition.  i would not suggest buying it new, for less money mantenance+revalve of suspensions offers a way larger increase in performance and safety

Edited April 29, 2017 by 30x26

[ohiodrz400sm]

Like 30x26 said, the hit you get off idle and when you crack the throttle is the biggest difference, and it's a big difference. Being a larger diameter, you will also get more power on top.

I don't know what other mods you have, but it's an integral piece of the puzzle if you start adding cams, big bore, MRD Z Pro, ect. and you want to maximize the potential of the engine.

[bumtarder]

fcr39mx will yield 4hp over stock when jetted correctly.On a 33hp stock motor that's a 12% increase in hp with just the carb alone.

[Spyvsspy]

6 hours ago, MyKLX400 said:

My carb seems perfect to me, however I am always looking for that next mod.

Is the FCR that big of an improvement over the stock one?

 

I'll let you know in a few days when all the bits and pieces arrive so that I can install my fcr39(along with the 3x3 mod and the Yoshi RS2 full system)

[Beta300REcat]

6 hours ago, MyKLX400 said:

 

Is the FCR that big of an improvement over the stock one?

 

Definitely.

 

Get one with the hot start and the TPS.  ?

[Spyvsspy]

1 hour ago, Bermudacat said:

Definitely.

 

Get one with the hot start and the TPS.  ?

What is hot start?  I heard tps isn't really an issue and can be eliminated 

[Beta300REcat]

12 hours ago, Spyvsspy said:

What is hot start?  I heard tps isn't really an issue and can be eliminated 

Hot start is nice for after a spill. Adds air to take care of the extra fuel that has spilled into your intake from the float bowl.

The no TPS thing was a myth started by a guy who used to frequent this board regularly, but left after not returning engines and money he had taken from many members.

EVERY gasoline engine varies timing based on rpm and cylinder pressure. The TPS controls the portion of advance dictated by cylinder fill, which governs cylinder pressure. RM250's, RM450's, KTM's, Ducatis, Yamahas, Hondas, Husquvarnas, Kawasakis, etc, ALL have a TPS to control this vital function. I added it to my carburetor because the aftermarket carb I purchased didn't come with it. Adding them later will cost$375, unless you can do the machining work yourself, which will save you $175.

More info on timing and Minimum advance for Best Torque (MBT)

https://www.hindawi.com/journals/jc/2011/678719/

[30x26]

this is the difference according to James Dean: stock, stock + jd kit , fcr + jd kit.

most of self tuned fcr will offer less power than the perfectly tuned fcr in the chart. 

 

 

 

Edited May 1, 2017 by 30x26

[sbmon]

Imo something else to keep in mind the power increase with the FCR is really about how the power is delivered than overall peak HP numbers. For example if your on the highway cruising at 55mph and instantly go wot the fact you have added the fcr carb is not that apparent. The seat of the pants gains are felt much lower in revs. From the reading I have done if you have any desire to go bbk the fcr carb is prerequisite for any decent gains from the bbk.

If price of the fcr is big deciding factor you may also look at the cvk40 carb as there are many people that have gone that route with the drz and have good reviews.

[BMSteve]

I'm so glad the Aussie E's come with the FCR's and stage 2 cams as well I think, saves a lot of mucking around.

..

[400eSM]

The throttle response is well worth it.

[MyKLX400]

Thanks for the replies everyone, from what I gather I am gonna hold off till I go 434.

The stock carb responds perfectly to me with the 3x3, JD jet and quick turn.

[Qqqqqqqqqqqq]

Yeah .. you will be impressed with the 434 / FCR and stroker crank . It will really have some POP

[Spyvsspy]

On May 1, 2017 at 8:33 AM, MyKLX400 said:

Thanks for the replies everyone, from what I gather I am gonna hold off till I go 434.

The stock carb responds perfectly to me with the 3x3, JD jet and quick turn.

After having the fcr39 and ordering everything to install it, I am wondering if I should stick with the bsr36 awhile longer.  I have had the bike for a month now(1200 miles logged in a month) and I bought it to learn some wheelies.  I think that the fcr will be too much for learning...