FCRs...

[alextrx850]

Quite interesting the difference in engine response with the just fitted Keihins..
Having used the standard carbs for so many years and knowing the way the package runs,..just like to share the experience..
I havent the easy use of a dyno, so I've only the feeling from the seat of my pants...so I have found the low torque is more tractable up and higher from 3 thousand with a better 4 thousand level rebreath....feeling is a 600 rpm worth of more dig in on the rear hoop.!
Haven't taken the motor to any higher rpm in fifth yet, but looking forward to it...not looking to any miracles, but what I've experienced so far is exciting....
Very good low around town fuelling.too..smoother which was an unexpected add.

Big question, I am using so far, the RAM AIR filter in the trx air box inlet trumpets inside a vented air box..makes a nice sound on full induction....but thinking to clip out the inlets and go without the box body....wouldn't Mind hearing the induction, so Long as its not too loud....
Smaller question, the ( rattle) ..I know what it is, but mine don't rattle too much , unless under load...guessing worn FCRs might rattle a bit more.
Gearing would be close to 17--40
Reality is 18--42 because of my VFR SSSA.
thoughts.

[Wombat]

How'd you go with the rubber intake manifolds?
Did you have to modify them to get the carbs on?
Mine are so perished, they'll probably crumble when I finally put my FCRs on.
Gonna order a new set of Ebay

Std jetting or did you have to experiment?

Bob

[Yoozy]

I've done a bit messing about with airboxes on a few bikes. I don't like the big airbox on any bike really, simply because they hide so much and get in the bloody way of everything, especially under the tank ala TRX. I nearly always put a foam filter on like you have, and generally find the bikes run a bit free'r? once you get them set up. They get any ram effect needed from around the tank. I love the induction roar but if it gets a bit loud I stick a bit of foam or zorst packing under the tank
I'm no expert, I just like dicking about.

[alextrx850]

Hi Wombat, all FCR carbs will come pree jetted to suit...if they are made for the Rex...that is with the TPS ..
Do a search for the Keihin dealer here in OZ Wombat,..as the import tax over one thousand dollars aust, will slug you an extra 180 smackers...I had a quote to build a set here around the 1160 mark plus post.
Rubber intakes in very good condition, no resistance to the fit up...e bay have some new ones I've noted.
Like your thoughts too Nob.

[Trixed]

Looks good Alex. Be interesting to do a dyno check on the increase. Am thinking of putting the same too. Just finished putting the fz400 lights on my Rex. Attaché bike looks more ballsy now!

[trixynut]

Std trx carbs like still air from airbox. Fcrs are ok with foam pods and junk the box.

[cobbadiggabuddyblooo]

The FCR's come std with a 150 main and after a dyno running l,bore 2 into 1 and the velocity stacks with a twin sock filter, I had to drop the needle 1 clip as it was getting too much fuel down low. You can see this from the dyno printout on sandune51 thread on the Big inlet and exhaust valves. As for the rattle , you can find a bit of a sweet spot just above idle that takes it away the easiest way I've found to get rid of the intake whistle is LOUDer exhaust and earplugs The dyno printout on the fuel reading shows a spike around 4000rpm and once I dropped the needle and leaned it out I picked up around 10hp from 40 to 50 right where I need it coming out of those corners...

[alextrx850]

Ok, how many notches are there on the needle Brian, the motor is starting easily from cold which gives the thought that it is slightly rich.
Will drop the needle down a notch.

[misterdimwiddy]

Pretty sure mine had 8 notches when I tried raising and lowering 2 notches before I blew up this week.

Not so sensitive to position from my experience. 2 notches made little noticeable difference either way.

Mines a bit rich at 160 mains so I may drop back to 150's.

I have blue bellmouths and a Ramair foam sock.

[spondontrx]

Why do you use the trx air box inlet trumpets instead of the ones that are supposed to be on there ?
I have made an air box witch is connected with pipes to the front of the fairing for my bike to give it some more air ,(the top is sealed of with the tank) less noise problems on track days and no problems when there is a strong side wind.

[Kenvis Repesco]

Really interesting thread. I am still in the should I shouldn't I mind mode about FCR's. I have never got the carburation exactly the way I want it on my TRX. There is this bloody annoying step (hesitation) when winding back on the power after shutting the throttle when in top gear. I have finaly got it to a stage where it really isn't a problem...but still its there. The only thing stopping me taking the FCR plunge is the comments people have made to me about them being either on or off. My bike is standard apart from cans, filter and DJ kit so would it be worth the quite hefty investment in a set of FCR's. But what tempts me towards them most is the chance to eradicate that iritating problem with the CV's, it really does bug me that much. What I would really like to do is try another TRX to compare mine with another... maybe the opportunity to do this will come on the North West ride out at the end of the month.

[dixonj]

If I manage to get my bike back together in time you are welcome to try my bike which has a stock newly rebuilt motor with a dynojet kit fitted and open cans goes ok. I had Skybones bike before selling it on and the power delivery on his bike was a lot different to my bike seemed to rev a lot better than my bike even though the bike is standard. I am in two minds about the Fcr's, would like to try a bike fitted with them just to see the difference.

[bubbaad]

I'm on the North West ride out so you can try mine....FCR's and big bore 2 into 1. Never heard of an 'on or off' issue, the FCR's smooth out the power delivery right through the range and it's much better at low revs than with standard carbs. I have fitted a 42t rear sprocket so this probably helps too.

[Kenvis Repesco]

Thanks chaps that would be marvelous.

[misterdimwiddy]

Really interesting thread. I am still in the should I shouldn't I mind mode about FCR's. I have never got the carburation exactly the way I want it on my TRX. There is this bloody annoying step (hesitation) when winding back on the power after shutting the throttle when in top gear. I have finaly got it to a stage where it really isn't a problem...but still its there. The only thing stopping me taking the FCR plunge is the comments people have made to me about them being either on or off. My bike is standard apart from cans, filter and DJ kit so would it be worth the quite hefty investment in a set of FCR's. But what tempts me towards them most is the chance to eradicate that iritating problem with the CV's, it really does bug me that much. What I would really like to do is try another TRX to compare mine with another... maybe the opportunity to do this will come on the North West ride out at the end of the month.

I recall seeing similar comment about FCR's being on/off, presumably because the slides move directly with your right wrist rather than having some delay with CV's while the vacuum pulls the throttle slide upwards more gradually.

For this reason I was expecting to have to be cautious initially and to have to adapt my riding style to suit. Nothing of the sort. They are completely smooth in the power delivery at all speeds (even at very low revs), instantly respond to throttle opening and the motor revs like a wild thing, particularly towards the top end where it used to rev out more gradually and run out of puff with CV's. Think I may change back to 16/40 from 16/42 because it gets to the redline so quickly in 4th and 5th.

Induction noise is however greatly increased; I have never been confortable riding with ear plugs but I found them necessary at Brands because it makes quite a racket with my 104dB system + the carb noise. Beautiful.

My advice to anyone is buy a set. I doubt you would be disappointed and they will always resell for good money. They are also very easy to work on (changing needles and main jets).

Phil