Anybody on here have any experience with running a newer (tps equipped) gs500 carb on an older bike?  I am looking for an extra set of carbs for my 01, and i have found a few of the newer ones for a good price.  Would a TPS equipped carb work with my bike if I just left the TPS unplugged?

I don't see why it wouldn't. The older bikes don't have a plug for TPS, so they're not even gonna know you have a TPS that's not plugged in. A lot of people recommend riding with the TPS unplugged on my non-GS500 bike because it causes the bikes to stumble sometimes.

Quote from: tt_four on February 07, 2012, 03:48:10 PM
I don't see why it wouldn't. The older bikes don't have a plug for TPS, so they're not even gonna know you have a TPS that's not plugged in. A lot of people recommend riding with the TPS unplugged on my non-GS500 bike because it causes the bikes to stumble sometimes.

That's what i was thinking.....I am hoping someone can verify through personal experience that this will work.....

Isn't the TPS what controls the idle on the newer carbs? I thought it replaced the idle speed screw, might be wrong.

I do not know about leaving the TPS unplugged.
To use the TPS, you'd have to change out your wiring harness, the ignition control box and your handlebar controls.
I've been learning about the differences as I build Phenix.
The 2001-2002 is a transition model. The carbs and wiring seem to be the same as 89-00 models. The controls are the newer style, with the older plugs as used on 89-00.

The 2004+ has a different ignition control box. There is wiring for the TPS. The handlebar controls have different plugs. The ignition control uses only one pickup on the right side of the engine so the timing rotor and pickups are different.

The ignition box also needs to sense 1st and 2nd gear (Neutral sensor has 2 additional wires for that). I have heard of that being disconnected with no effect. I guess the timing is slightly altered depending on what gear and the position of the throttle.

I think you might be able to use them without doing the complete change-over. I'm not sure what some of the extra vacuum switches and emissions stuff is on the newer carbs. I still have that to explore before I move a 2006 engine into Phenix. I have to (want to) eliminate the Calif. emissions that motor has and clean up as much of the extraneous hosing as possible.

I do know the carbs will fit. I've seen older carbs on a newer engine. I've checked the intakes and they are the same on old and new engines. You will need a new airbox because the air intake on newer carbs is smaller than on older ones.

My gut instinct says you can do it. I do not know what performance issues there would be. Probably none. I think a lot of the extra crap is for emissions. When you look at an old carb: gas hose and vacuum hose for the petcock. New carbs: a real cluster f*ck of hoses and wires.

Quote from: Dizzledan on February 07, 2012, 03:57:36 PM
Isn't the TPS what controls the idle on the newer carbs? I thought it replaced the idle speed screw, might be wrong.

Idle screw is the same and in the same place.

I have a 2005 gs500 with all the carb and emissions/tps crap disable AND a functional ignition advance mod.

From my limited understanding, the new ignition has a watered down version of ignition control, for the purpose of passing new CARB standards, AKA, it changes the ignition based on rpm and throttle position, making it leaner under 3-4kish..

Remove the TPS (or unplug it) and it goes into "safe mode" AKA, the old school mode where it is a fixed ignition system. That is what makes the ignition advance work and not get over-ridden.

Only thing I have on my bike is a vac line to the petcock, and a fuel line.

Everything else is capped off, except for the 2 carb ports that you sync with.

I ran a small line to a male-male connector that is zip tied in a convienant location, and plugged, so that when I sync my carbs, I dont have to fish my hands in a location designed to fit little asian hands.

Thanks for that info on the bazillion hoses on the new carbs.
I'll try cutting out all that crap before I transplant the engine into Phenix - just for fun - so see how it affects it.

Quote from: adidasguy on February 07, 2012, 06:33:16 PM
Thanks for that info on the bazillion hoses on the new carbs.
I'll try cutting out all that crap before I transplant the engine into Phenix - just for fun - so see how it affects it.

If you need a hand, call me.

And, being you do have older carbs, replace the white top on the new ones that have the vac ports with the black ones from the old ones, It wont help anything, but it will eliminate a possible point of failure should a cap pop off. 

Quote from: xunedeinx on February 07, 2012, 06:23:40 PM
I have a 2005 gs500 with all the carb and emissions/tps crap disable AND a functional ignition advance mod.

From my limited understanding, the new ignition has a watered down version of ignition control, for the purpose of passing new CARB standards, AKA, it changes the ignition based on rpm and throttle position, making it leaner under 3-4kish..

Remove the TPS (or unplug it) and it goes into "safe mode" AKA, the old school mode where it is a fixed ignition system. That is what makes the ignition advance work and not get over-ridden.

Only thing I have on my bike is a vac line to the petcock, and a fuel line.

Everything else is capped off, except for the 2 carb ports that you sync with.

I ran a small line to a male-male connector that is zip tied in a convienant location, and plugged, so that when I sync my carbs, I dont have to fish my hands in a location designed to fit little asian hands.

So, I think this is the answer that I have been searching for......the carbs from a newer bike will work just the same as the older carbs with the TPS unplugged........Right

Quote from: xunedeinx on February 07, 2012, 06:23:40 PM
I have a 2005 gs500 with all the carb and emissions/tps crap disable AND a functional ignition advance mod.

From my limited understanding, the new ignition has a watered down version of ignition control, for the purpose of passing new CARB standards, AKA, it changes the ignition based on rpm and throttle position, making it leaner under 3-4kish..

Heeeyy... i wonder if that's the reason why I and others, have vibes in low gears, *until after 4k or so*.

meh, probably not.

Quote from: xunedeinx on February 07, 2012, 06:23:40 PM
...
Only thing I have on my bike is a vac line to the petcock, and a fuel line.

Everything else is capped off, except for the 2 carb ports that you sync with.
...

Doesn't that affect the emissions? Id like to remove all that c**p with the extra hoses, but my emissions get checked yearly (UK - MoT). Also, Would it affect performance at all?

I don't see how timing can make it leaner. Lean depends on air and gas mixing in the carbs? Rejetting affects lean/rich doesn't it? So not sure how timing advancing would affect lean, other that changing firing time to allow more complete combustion for emissions maybe at the sacrifice of power.

There is a vacuum switch opposite end of the carbs from the TPS. Anyone know what that does? There is also the PAR system - whatever that is.

What does the extra hose do that's on the diaphragm caps?

Anyone have an annotated drawing or photo of newer carbs indicating what each hoes and thingy does? Anything indicating "don't need" or "could remove" and "must stay"?

Washington doesn't have emissions testing for bikes, so I'm OK doing whatever I want.

IDK what it all does honestly, all I know is that My ignition advance worked AFTER I unplugged the rats nest.

Quote from: xunedeinx on February 08, 2012, 01:57:03 PM
IDK what it all does honestly, all I know is that My ignition advance worked AFTER I unplugged the rats nest.

That would be a nice write-up. Pictures? Videos?

Next time I rip the tank off I'll take some decent pics for you guys!

its called the piston lift control system
i understand that it allows vacum to be appliued to the top of the diaphram speeding up the throttle response
its not well documented anywhere althoiugh the haynes manual briefly touches on it see pg 3-11
if anyone out there has more info i would be interested

So as I understand it, with a newer ignition control unit, you can .....
1. remove everything from newer carbs and they run like older carbs
2. Ignition control will go into a "safe" mode and run like an 89-00 bike with the TPS disconnected (or if using older carbs)
3. If the neutral sensor doesn't indicate 1st or 2nd gear, no big deal. Control box can live without those connections.
4. We can all breathe just fine without that PAIR system found on the newer carbs so cap that off, too.

This would be good. In doing the bike builds I find
1. I like the newer controls
2. Newer controls are, well, newer and not sun bleached
3. Newer wiring harnesses connect everything under the front part of the tank rather than in the headlight bucket so easier to deal with wiring
4. Good newer wiring harnesses are easy to find. Most 89-00 harnesses are crap.
5. I then can use new or old carbs, new or old engine as long as I put the single pickup on the engine for the newer control box.

I have plenty of older carbs so I can take the black caps off and put them on the newer carbs. I understand that is preferable to just capping off the ports on the newer white caps. Correct? Or does it matter?

Here's another question: In general, would it be better to run newer carbs as older carbs than to run with older carbs? (By that I mean remove all the baggage, stripping it down to just gas IN and vacuum line to the petcock.)

Another one: In wiring Phenix, I see coils have a plus and minus. Curious, since it is just a pulse transformer, how critical is that? What if the wires are reversed on a coil? Curious about this because I wonder if it could sometimes be the cause of some poor running bikes. Doesn't seem like it would make any difference - a spark is a spark. The winding of the coil the ignitor connects to is isolated from the secondary (spark) winding and isolated from the frame.

Quote from: adidasguy on February 09, 2012, 05:56:46 PM
So as I understand it, with a newer ignition control unit, you can .....
1. remove everything from newer carbs and they run like older carbs
-I believe so, Buddha may know more than mysef.
2. Ignition control will go into a "safe" mode and run like an 89-00 bike with the TPS disconnected (or if using older carbs)
-From my experiance, yes, it also allows the use of an ignition advance. AKA, if you want to go more than 5 degrees, use 93 gas and reap the benefit of 1 more hp
3. If the neutral sensor doesn't indicate 1st or 2nd gear, no big deal. Control box can live without those connections.
-IDK, Havent tried.
4. We can all breathe just fine without that PAIR system found on the newer carbs so cap that off, too.
Screw California

This would be good. In doing the bike builds I find
1. I like the newer controls
-Yup
2. Newer controls are, well, newer and not sun bleached
-Unless its a bike from Florida (fml)
3. Newer wiring harnesses connect everything under the front part of the tank rather than in the headlight bucket so easier to deal with wiring
-Yes, kinda, except the wires are shorter.this is fine for me, But this weekend I think I'm cable sleeving all my wires for space and appearance.
4. Good newer wiring harnesses are easy to find. Most 89-00 harnesses are crap.
-Depends in the region, but yes. Up in the northeast when I was there, there were a LOT of early, crapy, gs500's
5. I then can use new or old carbs, new or old engine as long as I put the single pickup on the engine for the newer control box.
-What do you mean pickup? I have 2 ignition coils if thats what you mean?


I have plenty of older carbs so I can take the black caps off and put them on the newer carbs. I understand that is preferable to just capping off the ports on the newer white caps. Correct? Or does it matter?
-Correct, its why I tried to get some black tops from ya! If you can, can you take disassembly pics of your black tops, and I'll take pics of my white tops, and we'll see if they can me modified to be the same thing. AKA, some JB weld and paint

Here's another question: In general, would it be better to run newer carbs as older carbs than to run with older carbs? (By that I mean remove all the baggage, stripping it down to just gas IN and vacuum line to the petcock.)
=BIG YES! Pilot, Mid-main, and Main jets. A lot easier to get a very good tune. From my understanding, the mid-main helps a lot when you change exhaust legnths, and get a lot of dead spots in the middle of the powerband. The more tune-ability, the better off you are. Buddha probably knows more, but as I see it, if I have the opportunity to change my exhaust lengths before the y pipe, or make it a dual with an x-over pipe, having 3 jets is better than 2.


Another one: In wiring Phenix, I see coils have a plus and minus. Curious, since it is just a pulse transformer, how critical is that? What if the wires are reversed on a coil? Curious about this because I wonder if it could sometimes be the cause of some poor running bikes. Doesn't seem like it would make any difference - a spark is a spark. The winding of the coil the ignitor connects to is isolated from the secondary (spark) winding and isolated from the frame.

-I have absolutly no experiance with the older bikes, wouldn't know. Would be nice to be able to rug up two small automotive coils for a distributor, so that way we could have a lot hotter spark, and be able to run with quad point irridium plugs for better burns...

Maybe some of my replies are more beyond the capabilities of the gs. From what I read, all we can really do before its unreliable is mill a bit off the head, enlarge the valves a bit, remove the counter balancer and balance the crank.

But, if we can make it breath better, give her better spark, get more ail and fuel in, and give her better operating efficency, she will live a longer, healthier, and productive life than the unbalanced compromised hunk that she was born.

I don't think you understood my question. Not asking about engine mods or milling out the engine. I don't know where that comment came from.

Mainly - can we just remove the crap on the newer carbs and run them in a simple way like older carbs: gas in and vacuum to the petcock.

The rest was comments on what I like on new wiring .vs. old wiring, and so forth.