FCR tuning - Stumble at one specific RPM

good to know. so all you need is the eddy currant option. thanks.

 

Kurlon,

If you have a well respected tuner tell you the 15 is better, and he has 10 years experience with that setup, why wouldn't you get them before your dyno visit?

 

Because at this point, 'getting' 15s means going full custom one offs. Setting aside the 4 x or more cost per unit ($400+ for a set of stacks puts me a good way towards converting to EFI) it's highly unlikely I could get a set prior to my next race round, without adding more multipliers to the cost. This is without knowing if my machine will like them. My primary goal is to improve as much as I can without blowing a hole in my budget for the next race weekend.

Now, the other aspect I'm working with is my motor build differs quite a bit from the past killer 400 SB setups. I'm also running a track that very much favors as wide a spread of power as possible vs maximum peak HP. If the shorter stacks suck out too much midrange they won't be a good fit for NHMS. They might make more sense for say, Daytona so it'd be good info for my notes but right now I'm a one track racer. I can get 30s now cheaply enough that I'm willing to roll the dice on them on a whim. If they don't work out, I haven't wrecked my season.

Don't get me wrong, I love the advice I'm getting from 400 racers and tuners, but I have to temper the suggestions against what my budget will allow and my short and long term goals.

In the mean time, off to see if there are any adjustable main air jet kits floating around... got adjustable slow air jets, need the same for the mains...

 

There is also a z-cell link available now so you can get direct torque readings off the drum rather than computed based on HP and RPM.

 

I ran FCR 33's on my FZR400. I don't remember where the needles were set, but I ran 120 mains.

13:1 Cosworth pistons and one cam (IIRC, it was the intake side) from the FZR 600.

The FZR 400 exhaust cam is actually bigger than the 600 one, or I am backwards. Either way, it does drop right in.

Change valve springs every 8 hours.

 

Kurlon,

I can definitely understand not wanting to pay $400 for a set of stacks. You mentioned getting some machined, and I had no clue they are that much. Sounds like YEC stacks for a DSB R6....I think I heard they are over $700.

 

I have set of those aluminum blue ones, they are 20mm. Not sure where exactly you measure them but 20 is overall height, 15 to the radiuses top.

 

Oh really... Large body or Small body FCR fitment?

 

I don't know. Did not know there are different ones
They fit 39's and 41's.

 

Those are 'large body' then. They'll have a larger ID on the carb end, and I think the mounting bolts are further apart. The 'small body' FCRs are the 28mm / 32mm / 33mm FCRs, the bigger body is used on the 35s and up.

 

I guess, they are ~59mm bolt spacing and ~42mm hole.
I never used anything less than 39

 

$1200 (from Graves). Much cheaper to blatantly copy and make yourself.

 

WOW!!! Really!?!?1 Christ! I have two sets! I better damn sure hold on to these. Kurlon I can let you borrow a set possibly. They are so short that they had to be drilled.

The other set I have are off of my CBR ram air set up that I got from Japan.

How do you measure them to know they are 15?

 

Wow, I didn't know they were that much and I thought $700 was nuts. Do they make a huge difference? Other than the fact the riders are better, is that where the extra speed is coming in on DSB vs. SS?

 

That price is for the ones made by MB in France, and that was 2012 pricing, so it may be more. They are shiny and all, but not worth half that price, really. It's just a case of needless markup.

They add a lot of top end, especially above 14K, but there are others custom made that are just as good.

 

The height is measured from the bottom of the mounting flange to the height of the outer lip.

http://www.takegawa.co.jp/detail/fcr_tmr_air_filter_detail.pdf for an example. Only, instead of measuring to the top of the filter mesh, stop at the top of the
stack itself. Those Taks end up being 23mm high as measured, but at 75mm wide they won't fit on the rack. Oh, and they're $90 each.

 

These?

 

Those, those are the shorties!

 

Straight from Japan via HRC. Cost me a fortune.

 

The moment they were stamped HRC the price doubled at least.