My replacing the stock carbs

Posted: Fri May 09, 2008 6:33 am

Early GSXR carbs off eBay, $35.00. Eight hose clamps, $13.00. One radiator hose from auto parts store, $10.00. Piece of plastic plumbing pipe I found laying around in the garage, $0.00. Not having to mess around with the stock carbs that I hate, PRICELESS!

I first stuck the straight end of the hose onto a manifold, secured it with a clamp, eyeballed it, then using a sharp knife, I proceeded to cut.

After cutting all four, trial fit the carbs on and make small adjustment cuts if needed.

I then cut that thin walled piece of plastic pipe with my hack-saw to insert into the boot in order to smooth the transition from the carb to manifold. Shape and file as needed.

The right one has the pipe inside vs the left with nothing. This will also give the boot added strength and stiffness.

Once you have it all on, tighten all of the clamps and what you are left with are choices of pods or velocity stacks. Oh, and relief from the stock carburator blues.

Posted: Fri May 09, 2008 7:45 am

that looks nice and easy: what is the spacing of your gsxr carbs ?

andrea

Posted: Fri May 09, 2008 11:44 am

I have done this conversion on other bikes and they are an excellent, of not the best, choice of CV carbs for older bikes. I've got to admit, however, that i don't have any of the angst over the stock carbs that many here have.

Posted: Fri May 09, 2008 5:17 pm

How early, do you have a year range on the GSXR carbs. What model GSXR?

What did you put these on? 900? 1100? other?

Posted: Fri May 09, 2008 5:40 pm

djhurayt wrote:

How early, do you have a year range on the GSXR carbs. What model GSXR?

What did you put these on? 900? 1100? other?

86-88 GSXR1100, 34mm Mikuni.

86-87 GSXR750, same.

On my current 82-750F street ride, past 750F street ride and current pics are of my 750 track bike, with 900 cams.

Katana 1100 had these carbs as well..600 & 750 Katana & later model, oil cooled GSXR had the better "Slingshot" Mikuni's up to I believe 94..Suzuki changed the later models with I think, lesser performing EPA happier type.

Look at the inlet side of these carbs, facing the filter. The good ones look like a velocity stack inlet, these have composite semi-flat slides. Most are 36mm. All have the neoprene/rubber diaphrams. I think that these would be nice on 900/1100 engines.

I'm a big fan of these Mikuni carbs, very easy to tune, NO CHOKE PLATE! Pod & velocity stack friendly! They are also 3 to 4 pounds lighter..

Posted: Fri May 09, 2008 5:44 pm

andrea wrote:

that looks nice and easy: what is the spacing of your gsxr carbs ?

andrea

I'll have to measure them, but they are tighter in than the stock. I'll try to post a side by side pic of both.

Posted: Fri May 09, 2008 6:03 pm

I too am a big fan of these carbs. they truly are a doddle to tune on any bike I put some on a laverda triple way back when I had hair. I was the first anywhere to do it, but it worked so well many other claimed they did it first. One guy in Australia even made a kit for the switchover.

Only worry is that the flat slides are pplasti and the bore they run in is a plastic insert (at least mine were, I believe mine were 1988 36mm jobbies). But without an airbox to steady intake pulsations (I ran pods), the slides jitter bugged up and down and eventuly wore so there was a lot of side to side play. Took a while as I had about 40,000 or 50,000 kiloemtres by the time I got rid of the bike.

Posted: Fri May 09, 2008 6:32 pm

These are CV, IE vacuum lift carbs also right?

Posted: Fri May 09, 2008 6:47 pm

I'm mystified here. All that work to still get CV carbs? The extra size won't matter because as CV carbs they will only flow as much as the engine demands. You can't get that super dense pack of air and the resultant extra power that comes with true direct lift carbs with those! Also, that plastic may deform or melt after a time in the engine's heat.

Posted: Fri May 09, 2008 7:10 pm

Dear AMC

most everyone here seems to think that direct lift carbs are some sort of magic pill. They may argue that FCR are better than RSs or whatever.

yet, with the exception of Blainemotos super duper hot rod, every time someone on this site slps on some of these carbs, tells everyone how they are pulling fifth gear wheelies with what must be at leasst 157000 horsepower, yet when they actually dyno them, they get, surprise, surprise 94 or 98 or if they are fasterspider 88, horsepower. Everyone seems to accept that a) the stock carbs are shit and b) that any direct slide carb is better, but when the proof comes to the dyno, it just hardly ever materializes. (and, yes Sonicrete, please bore us with yet another diatribe of how in 1994 on May 7th at Santa Ynez, with air humidity this and postal zone that, you shifted at 10,721 rpm and did 10.27133456923 quarter mile at 141.122345/infiniti miles per hour--- have you figured out that all this is boring yet?)

I mounted these CV carbs on bikes -- i.e the Laverda I mentioned earlier -- where the CV carbs made more horsepower than the direct lift dell'ortos they replaced. My CB, with absolutely bone stock carbs and pipes, makes a lot more horsepower than any of those FCRed hot-rods.

Yes, as Blaine's bike illustrates, a set of direct lift carbs can make a difference -- on a perfectly set up bike where evry part of the system matches. But as a solution to all that ails a CB, I think not. Show us the pudding.

I try not to get riled up, but this guy has a great idea, he's using a great set of carbs that he (and I) have proven to work great, are extremely easy to set up (basically leave the pilots alone, up a clip on the needle and two main jet changes were all that was needed in my experience) and work on a lot of different bikes (in fact, the most hot-rodded CB1100R, I have ever seen, out of Japan, uses these exact carbs). Yet you poo-poo his efforts based on experiments that except in the one case I've already mentioned twice have failed miserably.

This is a good thread. next thing you know Sonicrete is going to jump in and tell this poor guy what an obvious idiot he is, how could he have even thought of something so stupid and we'll lose yet another imaginiative, useful thread. So you know what, keep all your friggin naysaying to yourself.

Man that felt good. Now i'll just head to the boxing club, beat the crap out of the sparring partner and all will be right with my Friday.

By the way, Melchiro, in case you didn't quite grasp the subtlelty of my message, good job, keep posting on this subject. if i ever replace the carbs on the 1100R (which i doubt considering how well it's running0 it would be with these exact carbs. for some reason, they seem to be easier to set up to anything and will adapt to almost any motorcycle.

David

Posted: Fri May 09, 2008 9:23 pm

Okay, you guys have my attention! I have seen these carbs setup on many Japanese bikes. I will assume that the carbs I get will not have the correct jetting. So, for a stock 750 with 900 cams, what is the jetting sizes? Please be specific.

Posted: Fri May 09, 2008 11:35 pm

Uh, felt good huh? Wow. Maybe you should look at a physics book once in a while. Vacuum carbs always jet closer because they flow close to the same amount based on the engine's suction. Since the velocity stays much closer to constant (as in "constant velocity") the jetting by nature's hand will be closer. Same size carb will work on many sizes of engine because engine only lifts slide amount needed. This means someone can brag how much bigger carbs are and "it's running so much better!" when the reality is that it's about the same. Since fuel closer tied to constant air as in slide locked to needle and slide taking pretty much an assigned position in bore based on engine draw, jetting no problem. Try that with what everybody around here calls a real carb, won't work. Rider can now artificially put slide wherever he wants, that means wide open at 2000 rpm if desired. If you can't jet for that, you'll be in for troubles, just look at all the people around here that install direct lift and then ask for the "exact" jetting needed as if that's possible. Wide open at 2000 is totally different than at 8000. My view is that MOST people have no business touching carbs. That said, everybody will do it and then tell you how much better it runs. I've heard that hundreds of times, it means nothing to me except that most people don't know what real horsepower is. Direct lift carbs allow MAXIMUM DENSITY of air to enter motor, especially at less than full rpm. Properly sized and setup, they can be the difference between a bike that slowly lifts the wheel powering through a gear and one that snaps up wheel so violently that bike flips backwards. They are harder to setup and resultant bike will be harder to ride if it's right. Max air density will ALWAYS make more all around power than less density you get with CV carbs, if you have trouble with that one, you need to complain to God, he made the rule. I've been through LOTS of the same issues with cars and Holley type carbs both vacuum and direct type secondary. Direct again harder to tune but ran faster when right. As far as Laverdas and Dellortos, well you work with what you got, I considered both back then dogs, old expensive technology when other people moving into the future. If going to all the work, why not just run the stock stuff?? Those are no harder to understand than anything else, except most people say they're lousy. You're gonna say that when you don't understand them.You say 1100R, stock carbs and pipes, it'll beat anything! So? YOU'RE RUNNING A STOCK BIKE and telling everybody how fast it is. Real world it's probably only as fast as any other 1100. My guess you'd be like everyone else I've seen that get ahold of REAL power, it'll not only quieten you down
but scare you as well. The very fact that you act like direct lift carbs are nothing tells me you have never experienced them right sized and well set up, at least on a motor that makes HP. Your CV setup won't touch 'em except maybe in smoothness, but they won't rip your eyeballs out like the others will when you get ALL THE WAY INTO IT.

Posted: Fri May 09, 2008 11:49 pm

has anyone tried these with different variations of stock manifolds ie 1,1,4,4 or 2,2,3,3?

CB1100F Joined: Mar 03, 2004 Posts: 3278 Location: Seattle

Quote:

This is a good thread. next thing you know Sonicrete is going to jump in and tell this poor guy what an obvious idiot he is, how could he have even thought of something so stupid and we'll lose yet another imaginiative, useful thread. So you know what, keep all your friggin naysaying to yourself.

If not Bill, Im sure Bulldaug will offer us his unfettered opinion.... roflmao

Personally, I think its a great, & novel idea. If it works, and gets rid of those 23+ year old POS stock CVs & airbox, who are we to judge?? Rolling Eyes

Quote:

yet, with the exception of Blainemotos super duper hot rod

AND Stoutblocks OMT...... Dont forget that one... He never dyno'ed it, but it performed very closely to Da Beast, and handled the 39mm FCRs quite nicely. Ive ridden it, so I know. He also had access to my jetting & cam timing numbers, so that made tuning them a breeze..

Posted: Sat May 10, 2008 12:03 am

Dear AMC,

Please PM. We can trade biking resumes i.e who's ridden more high-powered bikes, who's set up more bikes etc. The reason for the PM will become obvious. It will take about one sentence. And while we're at it let's put some serious f'ing wager behind it. OK? C'mon AMC, Please. I'm begging you. Please.

And if the direct lift carbs are so much better why are the people who brag about their horsepower always dismayed when they get them dynoed? Why is that AMC where is the proof in the pudding.

Posted: Sat May 10, 2008 12:07 am

Dear Melichor,

My apologies for highjacking your thread. Please keep up the good work. It's really great. Never mind the naysayers. They know not of what they speak.

Again my apologies.It's just that I've seen too many posters with good threads stop posting because some xxxxxxx puts them down and implies they know nothing.

Thanks

David

Posted: Sat May 10, 2008 12:10 am

Point taken Blaine the moto but again the exception proves the rule. Twenty six years of squids I've seen and if even one percent of them had the juice they claim the world wouldn't have an energy shortage.

I stand corrected on the Stoutblock issue. Thanks again

David

CB1100F Joined: Mar 03, 2004 Posts: 3278 Location: Seattle

Quote:

I stand corrected on the Stoutblock issue. Thanks again

No problemo David. Wasnt meaning to correct you, it was more like a reminder.....folks seem to forget Stouts OMT.... Cool

We now return you to our regularly scheduled thread..... Twisted Evil

Posted: Sat May 10, 2008 12:20 am

No worries. One day we'll have to discuss your bike. On PM if you don't mind. As I said the exception proves the rule. ANd that, my friend, is interesting.

Posted: Sat May 10, 2008 2:47 am

It's no exception, just one of the few that got it right. Would have mentioned Stout's bike, but why drag somebody else in?? It's HARD to tune carbs, that why CV's are fallen back on, they're more forgiving. No need to PM, either say it in the open or get quiet. I am not much of an expert on these things but have learned a little in 35 plus years of hiperf, mostly cars. I have done a pretty good chunk of 2 stroke tuning including porting and the results seemed to be exceptional when compared to others around here, maybe you boys elsewhere are better, that's always possible. Melchiro, I apologize for any seeming slant against you, not meant that way, I'm just callous sometimes I guess. I was just wondering aloud what the end goal was. I don't view those carbs as any better, in fact now you'll probably have torn or stiff diaphragms to worry about. It can't be that hard to find good stock carbs when everyone wants to get rid of their stockers. Mine were reliable as hell and I even had pods on them. Personally I agree with Sonicrete on dynos, they all read different so any comparison is useless, the numbers are worthless. You may as well drop your angle on that because it doesn't hold good logic. I don't buy into it because I've done enough drag racing with all contenders playing on the same level playing field (the strip) to see who's full of it and who's not. Have tuned enough eight barrel tunnel ram stuff to see the difference between direct carb and vacuum type. One thing direct will do is definitely break more parts, an indirect indicator of more power. They'll charge harder "on the big end" too, because the engine eats more air with throttles all the way open all through the gear instead of part way. I don't know where you get the dyno results but the ones I've read show more power when vacuum reading is at or below 1" of mercury through the gear pull. We used to race American Motors AMX 2 seater cars, one we had 395" motor, 11.5/1 pistons, single 4 bbl. Torquer x type manifold, 2.64 low 4 speed, 5.00 gears. We could not get vacuum below 3" in high gear, 850 cfm double-pump Holley, motor seemed to be calling for more carb even though by all the "books" 850 was too much. Ended up with an 1150 Holley Dominator modified to 1250 cfm on this engine, everyone said no fvcking way. Used this HUGE carb way before most could even seem to get them right on 454 bigblock Chevy, we even drove car on the street (did some street racing). Engine said a big yes and 3300lb. car ran in the 10.60-70s at 128-131 mph 1/4 mile through the MUFFLERS with slicks for bite. Most of the bigblock guys did NOT want to line up beside this car, it would outpull those 454s in HIGH GEAR. Yeah, I know, sounds like someone else we know, huh? My point is, there's a difference between someone who is a naysayer and someone who may actually KNOW something. I don't know it all, but what I've stashed in my book is pretty rock solid. Most of it is solid theory available to those who look hard enough, I try not to deal out bullshit. Any motor reduced down to lowest level is just an air pump with fuel added to produce work. Denser air as in lower vacuum in intake tract equals more power. No dyno is needed if the science is solid.

CB1100F Joined: Mar 03, 2004 Posts: 3278 Location: Seattle

A dyno is not the end all and be all of engine tuning by any means. However, it is a good yardstick to go by, and all things being equal, it DOES separate the men from the boyz.....the strip is another matter. Sure you can crank out the HP, but you have to be able to apply it to the ground consistantly.

Case in point: on any given day, rain or shine, high humidity or low, hot or cold, all engines will do thier thing, and then be compared. One engine may pull 130HP @ the rear wheel in Hoston, Texas, while in Denver it may only pull 124. If it kicked the crap out of engine "B" in Houston, it is a pretty good bet it will kick the same engines ass in Denver. Provided of course, that measures were taken for variables like, altitude, temperature, humidity, etc..etc...

My buddy races a triple nickel Chevy big block. 7.62 in the quarter, somewhere around 168-172mph thru the traps... And he tunes her constantly based on conditions. If mem serves, he said he was running around 1100 HP. Shocked

Posted: Sat May 10, 2008 5:07 am

Comparison photos as promised........

Posted: Sat May 10, 2008 5:09 am

CowTownBiomed wrote:

These are CV, IE vacuum lift carbs also right?

Yes.

Posted: Sat May 10, 2008 5:10 am

Amen brother. Dyno CAN be used to compare, but only same dyno, that's difficult when everybody has one, that's what starts all the -hit. My brother used to campaign a pro Camaro here in Texas in early 90s, 720 cu. in., 3 stage nitrous, supposedly almost peaked a 1500 horse dyno BEFORE nitrous switched on, then couldn't read it. Car run in "whatcha brung" heads up match races. Getting old enough, trouble remembering ETs but 7's maybe 7.20? I know held IHRA world's fastest prostock for a very short while (they allowed nitrous) at close to 200mph. I used to work on it and a string of predecessors. Every run something got changed looking for that last hundredth second. We used to get in some hellacious arguments on what to do with the slipper clutch every run! One thing I remember was how loud the individual cylinder hits were at idle. With MSD the engine could be idled down and the cylinders popping off sounded like sticks of dynamite going off, loud is not the word here!

Posted: Sat May 10, 2008 5:21 am

Motocanada wrote:

Dear Melichor,

My apologies for highjacking your thread. Please keep up the good work. It's really great. Never mind the naysayers. They know not of what they speak.

Again my apologies.It's just that I've seen too many posters with good threads stop posting because some xxxxxxx puts them down and implies they know nothing.

Thanks

David

Motocanada, (David) No apologies necessary Smile

I just wanted to show others out there what I did & how easy it was. This is the state of tune that I wanted & the look as well.

Posted: Sat May 10, 2008 8:41 am

melchiro wrote:

Comparison photos as promised........

thanks melchiro, might go your way myself (79-91-79 being mine's spacing)

andrea

Posted: Sun May 11, 2008 1:12 am

Those type carbs have rubber diaphrams inside instead of those heavy pistons. The "misses at 8000 rpm" is what those do when a diaphram gets a tear in it.

All results in the diaphram makes a perfect seal and the piston type do not,this makes it easier to lift the slide.

By the way my engines make a 150 HP on dyno tests,but I do not build a dyno mule but took it from the track to the dyno just to see what it did.

No matter the carb you only get the airflow through the throat and correct mixture and that is the best you can do. The smooth bore type have less resistance than an open bore carb but these differences are slight.

The 11/44 spigot deal is the best,the #2 & #3 rubber has a big kink in it,the #1 an #4 make the smoothest turn.

All the other brands used those diaphram CV's,only Honda those SU type piston CV's and suffered the performance loss for doing it. Those diaphram type work nice.

Posted: Sun May 11, 2008 7:47 am

sonicrete wrote:

Those type carbs have rubber diaphrams inside instead of those heavy pistons.

All the other brands used those diaphram CV's,only Honda those SU type piston CV's and suffered the performance loss for doing it. Those diaphram type work nice.

My little "How To do this" is not just limited to "GSXR" carbs. You can do this to any carbs out there. Even stock one if you want to. The better choices would be carbs with rubber diaphrams & an enriching circuit for cold start ups..This way, there is no choke plate to mess with.

Posted: Sun May 11, 2008 8:35 am

Nicely done Melchiro, I think I will try this on one of my future builds.

Have you any pic's of your bike together now?

Posted: Sun May 11, 2008 7:46 pm

1981CB wrote:

Have you any pic's of your bike together now?

You can track my progress in "My track Bike project" in the performance technical. Slowly coming together, bit by bit.