Author Topic: Yet another question about carbs - but not what you think...  (Read 1632 times)

Offline Funderb

  • Trade Count: (+2)
  • AMA Superbike Racer
  • ****
  • Posts: 605
  • Karma: +11/-0
  • Terrified by the future, haunted by the past
Yet another question about carbs - but not what you think...
« on: October 23, 2012, 02:45:37 AM »
This is for people who have ridden both new model, 3-jet carbs, and old model 2-jet carburetors.

I am thinking about an upgrade / carb swap to the 3 jet style gs500F era carbs. I've recently ridden around on a buds 07, and it just feels better, crisper, cleaner, no lulls or dead spots in the power delivery.

My bike have always been meh, with a lumpy power curve, even when stock and completely clean. I dyno-jetted them, which was a bad idea, the buddah kit/method is clearly better. I noticed maybe more power, but the same delivery. I know its not the valves or the engine, because i just rebuilt the damn thing, rings to seats.

Here's my question: Does anyone think its worth it to upgrade to new-style carbs on my 98? (I know theres a crap load of nitpicky things to do involving the vac system and maybe getting a new set of boots for them) Thats not the issue.


If you guys think it might be worth it, anyone that has a spare set of new style carbs they'd sell for the sake of science, i could keep my money on the forum rather than over at ebay. Im interested in trying this, if people are interested in seeing some results.
Black '98 gs500 k&n Lbox, akrapovic slip-on, kat600 shock, progressive sproings, superbike handlebars, 40/147.5/3.5washers

"I'd rather ride then spend all my time fiddling trying to make it run perfectly." -Bombsquad

"Never let the destination cast a shadow over your journey towards it- live life"

Offline 802 305

  • Trade Count: (0)
  • Local Club Racer
  • *
  • Posts: 34
  • Karma: +0/-0
Re: Yet another question about carbs - but not what you think...
« Reply #1 on: October 23, 2012, 07:43:02 PM »
I'm interested too, as someone with 91 carbs and an 01 engine, I thought about "upgrading" but wasn't sure it was worth it or if I would be able to hook up the TPS and PAIR systems.... when I took care of the carbs though I was pretty pleased with power delivery. Haven't ridden a new one though so I can't say .
from the 802 all the way to the 305!
and 907 in the summer!

Offline adidasguy

  • Playing with kittens in Heaven now...
  • Trade Count: (+117)
  • Motorcycle God!
  • ******
  • Posts: 10934
  • Karma: +518/-0
  • Grumpy Cat for President!
    • Pix of my bikes
Re: Yet another question about carbs - but not what you think...
« Reply #2 on: October 23, 2012, 08:17:25 PM »
From experience, I say the difference is minor and how you ride.
My older carbs all have been upgraded to 40 pilots.
Newer carbs are still all stock.
Stock air.
Different exhausts: though when changing, no noticeable difference in performance.

In general, the newer carbs may have a smoother power curve in the over 5k RPM range. Maybe a little more response at the 5k-7k RPM range.

Older carbs seem to run better than new ones in the 2k-3k RPM range. I do lots of city driving. Newer ones don't like to give power much below 3k RPM. The pilot jetting may be the difference. Newer one still have the USA pilot where older ones have the 40's as used in the rest of the world.

You do not need the PAIR system.
2001-2002 are 3 jet minus all the vacuum stiff, PAIR system and throttle position sensor. Given that, you should be able to run newer ones fine without the TPS. All run fine without PAIR (and without "canister" if a CA model). There is a vacuum operated switch though I have yet to determine its function. 01-02 does not have it so probably can run without it connected as long as the vacuum lines are plugged if it is removed or broken.

2001+ have dual throttle cables - a pull open and the other one pulls closed. I guess to prevent throttle from ever getting stuck open. Makes sense. as a result, the choke cable is different and mounts on the left carb instead of the right one.

The TPS combined with the neutral sensor addition of 1st and 2nd gears adjusts timing.

I may pick up a set of 2001-2002 carbs. however, not using the TPS and vacuum switch should make 2004+ work the same.

If you want to use all the features of the 2004+ carbs, you do need to change the wiring harness and swap out the neutral switch. Always remember that 2004+ left hand controls are the same. 2004-2005 right hand are one plug. 2006+ the plug changed because the headlight was wired through the starter button. 01-02 are again their own unique plugs. The remainder of the 2004+ wiring is all the same

So given what the 2001-2002 carbs are, I feel confident you can use 2004+ carbs without the TPS and vacuum switch connected to anything of you are running with 1989-2000 wiring.

I have a box of 2004+ carbs I plan to use on bike builds. One fixer-upper I might swap out for 2006+ wiring and use new carbs (It runs great right now so if it ain't broke - don't fix it!?!?). There was a time when you could get good carbs from running bikes for under $100. Now they all seem to be $175+ and many $250+.

Did I answer the question or babble on too long?


Offline bombsquad83

  • Trade Count: (+14)
  • World Superbike Racer
  • *****
  • Posts: 1839
  • Karma: +35/-0
Re: Yet another question about carbs - but not what you think...
« Reply #3 on: October 23, 2012, 08:32:27 PM »
I have 40/125/1 washer/3 turns set up on my old carbs with the stock air filter.  I don't really have any problems with how the power is delivered, but I have never ridden a GS with newer carbs either.  I noticed issues with power delivery when I tried to use a K&N drop-in without a restrictor.  I also also have noticed a little bit of a flat spot only before the bike is fully warm in mid-rpms.  Once it's warm, it's always buttery smooth from 2.5k up with a big kick in power at 7-9.5k.

Keep in mind that I replaced every part that I could inside the carbs with brand new parts.  Diaphragms, needle jets, jet needles, jets, and o-rings (of course).  Maybe your diaphragms are stiff?  That could cause lumpy delivery.
« Last Edit: October 23, 2012, 08:36:25 PM by bombsquad83 »

Offline Funderb

  • Trade Count: (+2)
  • AMA Superbike Racer
  • ****
  • Posts: 605
  • Karma: +11/-0
  • Terrified by the future, haunted by the past
Re: Yet another question about carbs - but not what you think...
« Reply #4 on: October 23, 2012, 08:40:20 PM »
thanks guys,
I generally keep the RPM in the 4-5k range, and that also happens to be where a nice flat spot in the power delivery is. its not bad, just kind of annoying. I'm looking at this set on fleabay right now,
Adidas- thats actually exactly what I was shooting for in asking the question. Great info for sure, thank you.

http://www.ebay.com/itm/Suzuki-GS500-Carburetors-Carbs-/221142826693?pt=Motorcycles_Parts_Accessories&hash=item337d23bec5&vxp=mtr

Now, don't you guys go and steal them, ya hear. :flipoff:
looks like they've been modified as a hybrid new/old style at one point. At the very least, if i can nab them for a lowish price, around 100 bucks, they'd be ideal for two jobs:

-Seeing if there is a change in bike behavior
-un-kerfluffling the current setup i have via freeing me from my dynojet b.s.
Black '98 gs500 k&n Lbox, akrapovic slip-on, kat600 shock, progressive sproings, superbike handlebars, 40/147.5/3.5washers

"I'd rather ride then spend all my time fiddling trying to make it run perfectly." -Bombsquad

"Never let the destination cast a shadow over your journey towards it- live life"

Offline bombsquad83

  • Trade Count: (+14)
  • World Superbike Racer
  • *****
  • Posts: 1839
  • Karma: +35/-0
Re: Yet another question about carbs - but not what you think...
« Reply #5 on: October 23, 2012, 08:44:59 PM »
I have some used black slides if you need to replace yours.  I think you would be surprised what difference a washer under the needle makes if you haven't done that already

Of course if newer carbs is an itch you can't not scratch, then by all means let us know how the experiment goes :).
« Last Edit: October 23, 2012, 08:46:04 PM by bombsquad83 »

Offline Funderb

  • Trade Count: (+2)
  • AMA Superbike Racer
  • ****
  • Posts: 605
  • Karma: +11/-0
  • Terrified by the future, haunted by the past
Re: Yet another question about carbs - but not what you think...
« Reply #6 on: October 23, 2012, 10:06:07 PM »
thanks bsquad, i may do that, we'll see how this bidding thing pans out, but yours may be the better solution.

Right now though, i've found a crack on my right intake boot and it has a tiny vac leak. funsies. they are original to the bike, so i'm not surprised. Fix that first, is suppose. haha
Black '98 gs500 k&n Lbox, akrapovic slip-on, kat600 shock, progressive sproings, superbike handlebars, 40/147.5/3.5washers

"I'd rather ride then spend all my time fiddling trying to make it run perfectly." -Bombsquad

"Never let the destination cast a shadow over your journey towards it- live life"

Offline adidasguy

  • Playing with kittens in Heaven now...
  • Trade Count: (+117)
  • Motorcycle God!
  • ******
  • Posts: 10934
  • Karma: +518/-0
  • Grumpy Cat for President!
    • Pix of my bikes
Re: Yet another question about carbs - but not what you think...
« Reply #7 on: October 23, 2012, 10:16:10 PM »
thanks guys,
I generally keep the RPM in the 4-5k range, and that also happens to be where a nice flat spot in the power delivery is. its not bad, just kind of annoying. I'm looking at this set on fleabay right now,
Adidas- thats actually exactly what I was shooting for in asking the question. Great info for sure, thank you.

http://www.ebay.com/itm/Suzuki-GS500-Carburetors-Carbs-/221142826693?pt=Motorcycles_Parts_Accessories&hash=item337d23bec5&vxp=mtr

Now, don't you guys go and steal them, ya hear. :flipoff:
looks like they've been modified as a hybrid new/old style at one point. At the very least, if i can nab them for a lowish price, around 100 bucks, they'd be ideal for two jobs:

-Seeing if there is a change in bike behavior
-un-kerfluffling the current setup i have via freeing me from my dynojet b.s.

Those carbs have been in my eye since they showed up. They are original, unmodified 2001 carbs. My collection does not have a set of original 01-02 carbs. I have 4 or so sets of new carbs in my stash and wondered the exact differences between the 2001-2002 and the before & after ones. 01-02 are the bastard years: not fully new and partly old. And that's all over the bike: mechanical, electrical, etc. Those are the most incompatible 2 years for the GS500. Don't know about 2003 but guess it is same as 2002.


Offline Funderb

  • Trade Count: (+2)
  • AMA Superbike Racer
  • ****
  • Posts: 605
  • Karma: +11/-0
  • Terrified by the future, haunted by the past
Re: Yet another question about carbs - but not what you think...
« Reply #8 on: October 23, 2012, 10:44:46 PM »
I figured they would be, adiadasguy, go ahead and get them.
Replacing the carb boots with new stock is going to be about 50 bucks, so I am going to pass on the carb experiment for the time being.

I'd rather play around with the carbs I have and go with bomb's slides and then try to reverse the dynojet thing I've got going now. It'll be the cheaper option either way.

There was a mint looking 2001 for sale in jax a few weeks ago, i thought of you when i saw it, hahaha.


Balls.
Black '98 gs500 k&n Lbox, akrapovic slip-on, kat600 shock, progressive sproings, superbike handlebars, 40/147.5/3.5washers

"I'd rather ride then spend all my time fiddling trying to make it run perfectly." -Bombsquad

"Never let the destination cast a shadow over your journey towards it- live life"

Offline adidasguy

  • Playing with kittens in Heaven now...
  • Trade Count: (+117)
  • Motorcycle God!
  • ******
  • Posts: 10934
  • Karma: +518/-0
  • Grumpy Cat for President!
    • Pix of my bikes
Re: Yet another question about carbs - but not what you think...
« Reply #9 on: October 23, 2012, 11:05:43 PM »
I have a box of carb boots.
I think I have way too many sets of carbs, too.
Probably do not need any more sets of carbs. Need to get rid of some.

Offline Funderb

  • Trade Count: (+2)
  • AMA Superbike Racer
  • ****
  • Posts: 605
  • Karma: +11/-0
  • Terrified by the future, haunted by the past
Re: Yet another question about carbs - but not what you think...
« Reply #10 on: October 23, 2012, 11:34:19 PM »
shaZam! i just bought them.

I didn't even think to ask you.. again. GAAAAH :technical: :technical: :technical: :technical: :technical: :technical: :technical:

Oh well, its only money.

if they are still cheap when bidding is coming to a close you should get them! i might anyway, i have some cash to deposit back home this weekend anyway. let me know if you're going to bid on them so we don't fight each other.
Black '98 gs500 k&n Lbox, akrapovic slip-on, kat600 shock, progressive sproings, superbike handlebars, 40/147.5/3.5washers

"I'd rather ride then spend all my time fiddling trying to make it run perfectly." -Bombsquad

"Never let the destination cast a shadow over your journey towards it- live life"

Offline bombsquad83

  • Trade Count: (+14)
  • World Superbike Racer
  • *****
  • Posts: 1839
  • Karma: +35/-0
Re: Yet another question about carbs - but not what you think...
« Reply #11 on: October 24, 2012, 01:07:22 AM »
Shoot me a PM if you want the slides and we'll work it out.

EDIT: Do you have to modify the white part of the slide too when you do the dynojet thing?  I have a set of those too...One of them has 1 of the 2 tabs on 1 side broken off, but it would probably still work fine.
« Last Edit: October 24, 2012, 01:08:47 AM by bombsquad83 »

Offline BockinBboy

  • Trade Count: (+4)
  • World Superbike Racer
  • *****
  • Posts: 1881
  • Karma: +41/-0
Re: Yet another question about carbs - but not what you think...
« Reply #12 on: October 24, 2012, 03:33:40 AM »
gsJack has posted his thoughts on the new vs. old carbs but I can't locate it at the moment... My memory tells me he felt like his older carbs gave more power delivery mid range with maybe slight less power on top end... And the newer carbs had less power mid range with more top end...

I dunno for sure, but it was along those lines that they seemed slightly different and still had their own power sections on the throttle position... My point is, I doubt you'll get the type of results you want... Maybe more chance of an overall even distribution of power with the newer carbs, but nothing a couple washers, correct float height, and a good carb sync can't fix.

- Bboy


Sonic Springs, R6 Shock, R6 Throttle Tube, Lowering Links, T-Rex Frame Sliders, SW-Motech Alu-Rack, SH46 Shad Topcase, Smoked Signals, Smoked LED Tailight, ZG Touring Windscreen

Offline bombsquad83

  • Trade Count: (+14)
  • World Superbike Racer
  • *****
  • Posts: 1839
  • Karma: +35/-0
Re: Yet another question about carbs - but not what you think...
« Reply #13 on: October 24, 2012, 11:48:46 AM »
gsJack has posted his thoughts on the new vs. old carbs but I can't locate it at the moment... My memory tells me he felt like his older carbs gave more power delivery mid range with maybe slight less power on top end... And the newer carbs had less power mid range with more top end...

It was the other way around, but you have the observations right.

Offline adidasguy

  • Playing with kittens in Heaven now...
  • Trade Count: (+117)
  • Motorcycle God!
  • ******
  • Posts: 10934
  • Karma: +518/-0
  • Grumpy Cat for President!
    • Pix of my bikes
Re: Yet another question about carbs - but not what you think...
« Reply #14 on: October 27, 2012, 02:34:45 AM »
Been thinking about this after seeing the reminder about the gear position switch for sale.

Simply swapping carbs from 2 jet to 3 jet may not have a lot of improvement. 2001-2002 had 3 jets but old dual timing system.

2004+ has TPS and gear position sensor that control the timing in the new ICU. So changing carbs should include changing your wiring to the new ICU to take full advantage of it. Probably changes timing most at WOT or when in 1st or 2nd gear.

Someone really into noticing performance should take a 2004+ and unplug the TPS and the gear sensor then compare performance. The 1st and 2nd gear are on a different connector from the neutral line so that can be disconnected and not affect the neutral sensor.

Offline noworries

  • Beloved resident troll. And damn proud of it!
  • Trade Count: (0)
  • AMA Superbike Racer
  • ****
  • Posts: 561
  • Karma: +22/-0
Re: Yet another question about carbs - but not what you think...
« Reply #15 on: October 27, 2012, 05:23:44 AM »
Cripes, I didn't even know my bike had a 2-3k operating range!!!! How do ya get there? And why?

Offline Funderb

  • Trade Count: (+2)
  • AMA Superbike Racer
  • ****
  • Posts: 605
  • Karma: +11/-0
  • Terrified by the future, haunted by the past
Re: Yet another question about carbs - but not what you think...
« Reply #16 on: November 06, 2012, 11:32:47 PM »
So here's what happened, bombsquad hooked me up with new slides, which was awesome,
i picked up a set of 147.5 jets from NCS, and threw the old needles, washer, and new slides and jets in.
Reset idle and all that fun stuff,
had a horrible dead spot at 1/2-3/4 throttle so i said, "hmm that sounds like the needle height"
kept riding it, and it got better as it warmed up, but still was crappy. (indicated lean condition)
I've now shimmed an equivalent of 3 washers ish with whatever detritus i could make washers from around the apartment. (i have to ride the thing in the morning.)

the dead spot is almost entirely gone, it idles great, responds to throttle great, and at WOT it screams, I would say its definitely an improvement over the DJ kit.

I think with the lunchbox, and the akro, which is a glorified (but high quality) glass pack, I could probably move up to 150s, and that would help where i've shimmed the needles excessively. Am I wrong?

either way, I'm happy to be back to real mikuni jets, and I'l be replacing my beer-can washers with real ones soon.
« Last Edit: November 06, 2012, 11:35:07 PM by Funderb »
Black '98 gs500 k&n Lbox, akrapovic slip-on, kat600 shock, progressive sproings, superbike handlebars, 40/147.5/3.5washers

"I'd rather ride then spend all my time fiddling trying to make it run perfectly." -Bombsquad

"Never let the destination cast a shadow over your journey towards it- live life"

Offline jestercinti

  • Skinny and still bat shit crazy
  • Trade Count: (+7)
  • World Superbike Racer
  • *****
  • Posts: 1774
  • Karma: +24/-0
  • Rockin' the Rustbelt in Oh High Oh
Re: Yet another question about carbs - but not what you think...
« Reply #17 on: November 07, 2012, 02:06:39 AM »
Funderb,

To answer your question, you will never know until you try.  You can buy 150s and throw them in.  If it is too rich, you have the 147s to go back to. 

Not sure if the 150s would help the washers since washers are mainly midrange and mains are 3/4 to WOT.  I am no carb expert, but you never know...it could work.

By the way, I have some extra o-rings, equivalent to 2 washers, and some extra #3 and #4 washers if you want them.  Free of charge.  PM me if interested.
Bikeless and Broke at the moment...

Offline Big Rich

  • Trade Count: (+8)
  • Motorcycle God!
  • ******
  • Posts: 3746
  • Karma: +52/-0
Re: Yet another question about carbs - but not what you think...
« Reply #18 on: November 07, 2012, 03:17:53 AM »
This is just a broad generalization about carbs, but I hope it helps:

Off of idle, almost all gas goes thru the main jet. Even at 1/2 throttle, the needle is up, but the gas is still spraying up thru the main. At wide open throttle, the gas is coming up thru the main and spraying onto the needle. So with shims under the needle, you'll still be getting slightly more gas at WOT than without any shims. Does that make sense?

Sometimes changing the number of shims will affect WOT, just the same as changing your main jets can affect all other throttle ranges (try running without any main jets at all - you'll notice).
83 GR650 (riding / rolling project)

It's opener there in the wide open air...

Offline Funderb

  • Trade Count: (+2)
  • AMA Superbike Racer
  • ****
  • Posts: 605
  • Karma: +11/-0
  • Terrified by the future, haunted by the past
Re: Yet another question about carbs - but not what you think...
« Reply #19 on: November 08, 2012, 05:33:53 AM »
thanks jester, I can pick up a boatload of washers from the local shop for free, so i'll save ya the postage for now.
I will washer it up, and then check my plugs later on for readings (i cleaned them up). will report soon.
Black '98 gs500 k&n Lbox, akrapovic slip-on, kat600 shock, progressive sproings, superbike handlebars, 40/147.5/3.5washers

"I'd rather ride then spend all my time fiddling trying to make it run perfectly." -Bombsquad

"Never let the destination cast a shadow over your journey towards it- live life"