Anyone running different carbs.

[Pat Conlon]

The carbs from a 1st generation FZ1 have spacing that's identical to the FJ......

Are you sure amigo? 77-85-77

I thought the FZ1 engine was a modified version of the YZF-R1 so the cylinder spacing is different.

[FJ_Hooligan]

Pat,
Prior to that post I set them on top of each other and the intakes lined up perfectly.  Even with the cam chain on the end, the intake spacing of cylinders appears to be the same.

I'd take a picture but it's such a pain to post pics on this site.

Check over on FB

I'm almost offended that you question a statement about carbs from me.  :-)

[Pat Conlon]

David....yea, what was I thinking?  I pulled your photo over from FB.

I looked all over the web for the FZ1 carb spacing
The Yoshurmia web site has the most complete listing for aftermarket carb fitments and strangely enough they have no carb listings for the early FZ1's or Fazers as they are known overseas.

Don't I remember (years ago) you saying the FZ1's  carbs were a PIA to work on?

[FJ_Hooligan]

Wrangling the spacers and sync springs is a PITA but they aren't terriblly bad.

The Ivan carb kit for the FZ1 carbs is a significant improvement over stock.  My son's Bumblebee FZ has one and it is noticeably stronger on acceleration than my stock FZ

Years ago I postulated that the spacing was similar but never confirmed it until now

[Pat Conlon]

So if the carb spacing is the same, the exhaust header should also fit?
Is the firing order on the FZ1 the same 1243 as our FJ's?

[ribbert]

Pat,

I'm almost offended that you question a statement about carbs from me.  :-)

Haha David....

































.... don't feel special.  

[FJ_Hooligan]

Pat,
The exhaust spacing doesn't necessarily mimic the intake spacing.  The intake spacing was probably kept the same to fit an existing set of carbs that Mikuni already had in production, saving the cost of reworking a new spacing.  Since the FJ has a center cam chain and the FZ1 has the chain on the right side of the motor, I would assume the intake runners are different lengths because the cylinder spacing is definitely tighter than the FJ.

And basically, they can channel the exhaust spacing to whatever they wanted/needed regardless of intake measurements.

Funny Noel.  :-)

[Bill_Rockoff]

So if the carb spacing is the same from carb'd FZ1 to FJ, does that mean the fuel injected ones have similar spacing on the throttle bodies?

First dimension I could find is that the FJR1300 throttle bodies are 78-88-78, which seems like the sort of difference you could make up in the intake boots, maybe with a heat gun or maybe just pulling the two inner ones 3mm closer together (less than 1/16" each.)

[Pat Conlon]

Bill, yes, the FJR throttle bodies are what Randy used on his FI system he developed for the FJ.
Randy had offset adaptors made to mate the FJR throttle bodies up to the 77-85-77 spacing of the FJ's intake ports.

However, like you asked...If the FZ1 throttle bodies have the same pitch as the early FZ1 carbs, we would not need offset adaptors.....Interesting.

I bet a jelly donut David knows the answer.

[Pat Conlon]

The classics come back.....from 9 years ago....

http://www.fjowners.com/index.php?topic=3381.0

I had to laugh....even back then someone had the balls to question the carb guru....
I wonder if Dan ever got his $5?

[FJ_Hooligan]

I don't even remember that Pat.  I guess I did do my homework back then but for....zzzzzzzzzzzzzz...got.  Sorry, had to take a short nap in there,

Also, I know nothing about the 2nd gen FI FZ1.  All of mine are 1st gen carbs.  

I think I bought that set of FZ carbs that Ed was selling back then

Dan had a lot of faith in me.  :-)

[Pat Conlon]

David, well now, as of yesterday, we can put your theory to bed.
I noticed the lip on the FZ1 carbs (manifold side) looks to be shorter than on the FJ carbs, do you think those FZ1 carbs will snap into the FJ's intake boots correctly?

On street bikes I'm a fan of CV carbs. However with my 1380cc engine (thank you RPM) using heavily rejetted CV36 FJ carbs,  I notice at ~8.2k to 9.0k rpm the arm stretching acceleration tapers off. The 36mm carbs run out of air flow. Even still, this bike has some serious kookaloo....

So using the logic of simple math from a 1200cc stock FJ engine I've increased the displacement 13% to 1380cc.
So at larger displacement comes a proportional increase in air velocity feeding those 83mm dia. Ross pistons.
Therefore if my 1200 cc stock engine is served by 36mm dia. Mikuni CV carbs, why not try some Mikuni CV carbs with 13% more area? What size would I need?
The area of 36mm is 101.7cm x 1.13 = 115cm
The area of a 38mm carb is 113cm...close enough.

Now where would I find a rack of 38mm Mikuni CV carburetors?
The 1990-94 GSXR 750 European version used what is known as the Mikuni BST38SS carbs (aka Slingshot carbs)






The problem is the GSXR carb spacing of 77-93-77 so these 38mm carbs must be modified to fit the FJ 77-85-77 spacing.
Several years ago I found a set for sale in England (the USA versions were only 36mm)
I sent them up to RPM for Randy to take a look see and get modified, as a low priority project.
Until today, I've totally forgotten about them.  Perhaps Robert can track them down. If times get slow, he can learn all about a completely different model of Mikuni Carb.  
https://www.partzilla.com/catalog/suzuki/motorcycle/1992/gsx-r750n/carburetor-other-than-califorina
http://oldskoolsuzuki.info/archives/531
http://didier.clergue.free.fr/gsxr/docspdf/mikuni_bst_understanding_carburetors.pdf

[FJ1200W]

I stumbled on this fuel injection setup -

[Pat Conlon]

Steve, those look cool but no way would they fit between the frame rails on our FJ's.
The XJR uses a backbone frame so there is plenty of room at the sides of the FI throttle bodies...not so with FJ's perimeter frame rails....how they taper in towards the seat.
Yes, of course the XJR throttle bodies matches the FJ cylinder spacing (same engine) but the throttle body assembly has a left side protuberance for the throttle position sensor...thus does not fit between the FJ frame rails.
That's why Randy went with the narrower FJR throttle bodies....that, and the fact that they are plentiful on FleaBay.

Cheers

[racerrad8]

Steve, those look cool but no way would they fit between the frame rails on our FJ's.

That was a build for a midget race car. If you think the FI wont fit, check out the mechanical fuel pump mounted to the left side of the valve cover driven from the intake cam...

I don't know much more about the set-up except where the intake manifolds came from.

Randy - RPM