gsxr400racer Carb Tuning.

[PitterB4]

I was going to PM Jay but figured I'd share with the group...

Hey Jay,

You always say a good way to tune is to see if problems get better or worse when you run w/out your airbox.  With my new set-up:

* throttle resp is very good down low.
* it positively pulls like a train up top - all the way to the r/l.
* at normal backroads speeds, it's not quite as crisp powering out of turns as it should be.  The problem is just barely noticeable but once it's warmed up, roll-on out of a turn at ~7k just isn't pulling on my shoulders like I would like.  
* the 4-5k flat spot is very minor and only lasts about 2 minutes.

So, I pulled my filter and popped the tank back on.  Down low, I'm still ok.  That 7-9k, 1/2 to WOT range, I've got NUTHIN'!  It boggs something awful.  I have to feather the throttle to get above that rev range.  Once above, it runs OK again.  Not great anywhere but OK low and high and almost not at all in the middle.  

Your diagnosis, sir?  (I'm thinking I'm lean on my floats.  If so, how much adjustment at a time.  Boy, I hate pulling those MFing carbs again!!!!!!!!!!!!!)

BTW - my settings:

* V&H headers/M4 can
* FP TI needles - middle position
* AF screws ~2.5 turns out.
* 110 mains
* Floats, stock height (~14.5)
* Airbox with a golfball sized hole on either side of stock hole.  Snorkle in place.

[gsxr400 racer]

put 112 mains in and if i did anything i would just shim the needle one way or the other, dont mess with float level i found out this weekend it changed my whole jettting by only going 1-2 mm different in float height.
the question is did it run better on the top a little learner? did it pull better from a a dead stop till i fell flat on it face? Its a matter  of finding out what worked and writting it down and from there if it was good or better on the bottom get 1 size smaller pilot , and the same for the main if it ran noticable better , but is also good with the air filter in try a 108 or something like that main , what your saying is your bike wants fuel in the mid range on the needle , If it where me I would have raised my needle up to see if it rain better with the air filter out and more fuel to the needle. See i bought this thing from k&n called like a color tune has a ega thing that goes into my pipe and reads if im rich or lean i love it verey handy and i think it only coast 150.00 USD.

[PitterB4]

It was worse everywhere - almost unrideable in the middle.  The bottom wasn't bad but still worse than with the filter.  It was hard to get into the upper ranges but the couple times I did, it didn't pull as well.

[PitterB4]

Jay - is this the Colortune thing you're talking about?

[gsxr400 racer]

http://www.knfilters.com/airfuelmonitors.htm

this would be what i bought.

[gsxr400 racer]

there is this one to but it was a bit pricy for me and has a few more features, like you can hook it up to your computer

 I didnt need all that and the one i got work great for at the track

http://www.widebandcommander.com/

[Brit-400]

Whilst this threads here i may as well ask - on a bike with a K+N filter and race can, is it worth fitting some GSX-R carbs? What will i gain/lose? Also, will my Dynojet kit for the Bandit fit/be worth fitting?

Thanks in advance.

[gsxr400 racer]

yes that is the best thing you could do unless you have a model that already has the 33mm carbs and yes the jet kit fits in the gsxr4 carbs, more power

[gsxr400 racer]

I was going to PM Jay but figured I'd share with the group...

Hey Jay,

You always say a good way to tune is to see if problems get better or worse when you run w/out your airbox.  With my new set-up:

* throttle resp is very good down low.
* it positively pulls like a train up top - all the way to the r/l.
* at normal backroads speeds, it's not quite as crisp powering out of turns as it should be.  The problem is just barely noticeable but once it's warmed up, roll-on out of a turn at ~7k just isn't pulling on my shoulders like I would like.  
* the 4-5k flat spot is very minor and only lasts about 2 minutes.

So, I pulled my filter and popped the tank back on.  Down low, I'm still ok.  That 7-9k, 1/2 to WOT range, I've got NUTHIN'!  It boggs something awful.  I have to feather the throttle to get above that rev range.  Once above, it runs OK again.  Not great anywhere but OK low and high and almost not at all in the middle.  

Your diagnosis, sir?  (I'm thinking I'm lean on my floats.  If so, how much adjustment at a time.  Boy, I hate pulling those MFing carbs again!!!!!!!!!!!!!)

BTW - my settings:

* V&H headers/M4 can
* FP TI needles - middle position
* AF screws ~2.5 turns out.
* 110 mains
* Floats, stock height (~14.5)
* Airbox with a golfball sized hole on either side of stock hole.  Snorkle in place.

Rob put it back together and just shim the needles a half a step see if that fixs it , but it is hard to just get rid of a minor flat spot usually you move it some where else. you have a better chance of removing a flat spot by degreeing the cams but thats a different ball game all together.

[PitterB4]

Thanks, Jay.  

Just to be clear (I typed a lot!), the only concern I have is the 7-9k 1/2-WOT roll on.

[gsxr400 racer]

yes try to shim the neddles

[interfuse]

Boy, I hate pulling those MFing carbs again!!!!!!!!!!!!!)

Suck it up.

I had mine off 3 times on Sunday. 10 am until 6 pm without stoping.  

And I'll probably tweak a bit more this weekend. I'd like to go do a dyno run soon and I'd like to have the jetting as perfect as possible.

[Brit-400]

yes that is the best thing you could do unless you have a model that already has the 33mm carbs and yes the jet kit fits in the gsxr4 carbs, more power

Thanks. Any way of me knowing which carbs mine are? Its an early jap 400.

[tomacGTi]

Rob I really suggest that termostat swap before dicking around anymore with your settings.

It made things that much more consistant on my bike and all I have is a Dynojet kit, Cobra pipe and a slightly modified airbox. The bike warms up in about two minutes and throttle is much more consistant across the board. If you're draining your coolant anyway for the track day, why not?

-Randy

Oh and as I side note, I run an AF meter in my car and what a difference it made tuning it. A wideband is so much more accurate but so much more money at the same time. Much, much easier to dial in fuel at different load levels

Rob, if you're playing around that much, you can have your exhaust shop (they should know you by name by now and buy you cookies at Christmas) weld in an o2 bung just aft of the collector in the midpipe somewhere and install one. After that, it's three wires to wire in an AF meter and they now make them small enough to mount anywhere.

Just a suggestion...

[PitterB4]

AFAIK (which is not exhaustive by any means), the US was the only market to get the 32s.  I can't imagine the Jap version would use them.  You probably have "GSXR Carbs."

Mike - carbs are definitely coming off again.  I was still using my old, pre-Kreem fuel filter.  Tore things apart, put it back together.... with the gunked up filter on BACKWARDS!!!!  Washed all kinds of garbage in.  Can you say "blocked pilots?"  Oh the joys of carb cleaning!!!!!!!!!!  

Thanks, Randy.  Just another thing I need to get to.  I've already got Engine Ice in there in place of regular antifreeze which is one of the reasons I've been hesitant to do it.