BDT 38mm carbs on a GS 1150

[jstewart]

All the way through!! Can they even work like that???
I am noticing the problem now I can't imagine….

The way they are now it still pulls fairly cleanly all the way through the rpm range, just can't seem to get it lean enough on the bottom or midrange and my milage has decreased noticeably. Im going to keep running it the way it is until winter. I ordered parts and they should show up soon.
I am debating electroless platting the emulsion tubes myself with a kit, have been doing some research seems easy enough. I will do an old one first to get a feel for it if I go that route.

Good luck Joe. The more I research these 38mm GSXR CV carbs the more convinced I am that they are a problematic application on a GS 1150. To start with they are downdraft carbs which makes float height setup critical on a side draft head. They also have design problems with premature wear of the slide guides and emulsion tubes. Joe you stated your emulsion tubes are worn out again after only 2000 miles...because of the guide wear. You are apparently going to try and resolve Suzuki's design problem on the emulsion tubes by electroless nickel plating. what are you going to do about the slide guide wear problems???

I really like CV carbs when they work properly but I just don't have the time to try and maintain and find increasingly hard to get parts for 25 year old carbs that have design flaws with premature parts wear in the carb design and are not designed for a side draft application. The guy that sold me the defective 38mm CV's on the GSXR forum finally refunded my money which covered part of the cost of a new set of Mic 36mm flat slides.

[Joe H]

Awesome on the refund! You will love the RS's, they work well and are easy to tune have a great sound at idle and gobs of power on top.

As I thought about how I ride now vrs then and the costs to go to RS's with jetting and filters, I will be ahead by a few hundred bucks. I don't drive it as much or as hard as I used to. So I decided to stick with the CV's because they do give much smoother around town low rpm behavior and produce good smooth power throughout the rev range because they work on air velocity and not throttle position. With good emulsion tubes and the Factroy pro kit they really work well for my driving habits and produce great power.
I bought them used with unknown milage and I put between 15 and 20 thousand on the carbs before this all started a couple years ago so they lasted awhile.

I think with Nickel plated Emulsion tubes and new slide guides and knowing the rate of wear on the guides has to do with how hard you ride, throttle changes, hard acceleration ect, and dirt, the way I ride now, and keeping my filters clean, maybe adding a foam sock over them, I should be good to go for much more than 20,000 more. Which at my current rate of riding that bike would put me past retirement age!! WOW, thats a depressing thought, I either need to ride that bike more or age less!

[jstewart]

Well guys I changed my mind and decided I just had to have a good set of 38mm GSXR CV's. So now I have 3 sets of carbs for my 1150 restomod project. Must be crazy but I love to experiment. First stage will be the stock carbs and air box without the lid & with K&N filter. I want to run the stock pipes and dyno my fresh 1229 to see how it likes the stock carbs, air box & pipes. I am going to show the bike with the stock look at a vintage Japanese motorcycle show here in Louisville in late September and then change the stock pipes to a new V&H header. Then I can start experimenting with the BST 38's & the 36mm mic carbs to see how each runs and is to live with in normal street riding. Plan to dyno these combinations to see how they compare to each other and to the stock intake & exhaust setup.

Awesome on the refund! You will love the RS's, they work well and are easy to tune have a great sound at idle and gobs of power on top.

As I thought about how I ride now vrs then and the costs to go to RS's with jetting and filters, I will be ahead by a few hundred bucks. I don't drive it as much or as hard as I used to. So I decided to stick with the CV's because they do give much smoother around town low rpm behavior and produce good smooth power throughout the rev range because they work on air velocity and not throttle position. With good emulsion tubes and the Factroy pro kit they really work well for my driving habits and produce great power.
I bought them used with unknown milage and I put between 15 and 20 thousand on the carbs before this all started a couple years ago so they lasted awhile.

I think with Nickel plated Emulsion tubes and new slide guides and knowing the rate of wear on the guides has to do with how hard you ride, throttle changes, hard acceleration ect, and dirt, the way I ride now, and keeping my filters clean, maybe adding a foam sock over them, I should be good to go for much more than 20,000 more. Which at my current rate of riding that bike would put me past retirement age!! WOW, thats a depressing thought, I either need to ride that bike more or age less!

[posplayr]

Good luck Joe. The more I research these 38mm GSXR CV carbs the more convinced I am that they are a problematic application on a GS 1150. To start with they are downdraft carbs which makes float height setup critical on a side draft head. They also have design problems with premature wear of the slide guides and emulsion tubes. Joe you stated your emulsion tubes are worn out again after only 2000 miles...because of the guide wear. You are apparently going to try and resolve Suzuki's design problem on the emulsion tubes by electroless nickel plating. what are you going to do about the slide guide wear problems???

I really like CV carbs when they work properly but I just don't have the time to try and maintain and find increasingly hard to get parts for 25 year old carbs that have design flaws with premature parts wear in the carb design and are not designed for a side draft application. The guy that sold me the defective 38mm CV's on the GSXR forum finally refunded my money which covered part of the cost of a new set of Mic 36mm flat slides.

I had 5 sets , now 4, (I sold the pristine set with only 2500 miles on them) of these and even undertook the slide redesign you mentioned, creating a jig and fabricated metal inserts to stop the ceramic slides from wearing down the plastic inserts. In the end, I figured it just was not worth the hassle especially if the thing was always going to be in a state of change due to the slide wear. I can still power wheelie with the CV's. You can purchase new slides, and emulsion tubes, but without some other changes the ceramic slide will chew up the sides as they have a long history doing.

[jstewart]

I had 5 sets , now 4, (I sold the pristine set with only 2500 miles on them) of these and even undertook the slide redesign you mentioned, creating a jig and fabricated metal inserts to stop the ceramic slides from wearing down the plastic inserts. In the end, I figured it just was not worth the hassle especially if the thing was always going to be in a state of change due to the slide wear. I can still power wheelie with the CV's. You can purchase new slides, and emulsion tubes, but without some other changes the ceramic slide will chew up the sides as they have a long history doing.

I am well aware of the slide guide wear problem as I stated in an earlier post. I don't figure it will be that much of a problem for awhile since I do not expect to put that many miles on the bike a year (probably 1,500 or less). Most of my riding is on a FJR 1300 or my VFR 1200. Plan on ordering a spare set of slide glides just in case.

[posplayr]

I am well aware of the slide guide wear problem as I stated in an earlier post.

My quote from you (below) actually said that but thanks for confirming the obvious.

what are you going to do about the slide guide wear problems???

The slides in the carbs I had with only 2500 miles were not bad, but just starting to show slide wear. Perhaps the question above is rhetorical, but that is what I was working on.

[jstewart]

Which CV carb are you using on your GS 1100? I am assuming when you say the slides on the set of carbs off the 2500 mile bike were starting to show wear you meant the slide glide inserts that the slides ride in???

Sorry for the statement (I am well aware of the slide glide problem), if you took offense. I was not being a smart ass just stating that I went ahead with the purchase of these carbs with full knowledge of the problems I face with the design. I just want to play around with them and see what I can do with them on my 1229 motor.

The best designed and performing CV carbs I have experience with were the 40mm CV's that Honda put on the 98 Blackbird. At 10 inches vacuum on a flow bench test I did they flowed 148 CFM which was more than the stock head flowed by a fair margin.

My quote from you actually said, that but thanks for confirming the obvious.



The slides in the carbs had with 2500 miles were not bad, but just starting to show slide wear. Perhaps the question above is rhetorical, but that is what I was working on.

[posplayr]

BS36SS

http://www.thegsresources.com/_forum/showthread.php?164565-AFR-Info&highlight=AFR+Info

[Joe H]

I just don't see the slide guide wear as a huge problem, I have somewhere between 15,000 and 20,000 miles on them myself with unknown milage before.
It is so dependent on riding style and filtration.
I don't know how the 36's wear. The glides are different between the 36's, 38's and 40's I think, don't know how it affect wear.
My 38's are worn and it is noticeable with fine tuning the carbs but the bike is extremely ridable and I would guess most people I know would never think they were bad. I just happen to know how good they can be. I think I could easily go another 10 or 15 thousand before it would make daily riding suffer.

Now that being said If I was looking for a tourer or a rider that I was putting 10 thousand or more a year on I wouldn't have done most of the mods I have done, and the carbs would go for sure. I just don't ride enough.

Also don't the RS wear also? I have heard they do, along with almost all flat slide carbs, is that true?? I don't know from experience only what I have heard.

Jstewart I can't wait to hear how it runs and the differences in the mods your planing.

[posplayr]

I just don't see the slide guide wear as a huge problem, I have somewhere between 15,000 and 20,000 miles on them myself with unknown milage before.
It is so dependent on riding style and filtration.
I don't know how the 36's wear. The glides are different between the 36's, 38's and 40's I think, don't know how it affect wear.
My 38's are worn and it is noticeable with fine tuning the carbs but the bike is extremely ridable and I would guess most people I know would never think they were bad. I just happen to know how good they can be. I think I could easily go another 10 or 15 thousand before it would make daily riding suffer.

Now that being said If I was looking for a tourer or a rider that I was putting 10 thousand or more a year on I wouldn't have done most of the mods I have done, and the carbs would go for sure. I just don't ride enough.

Also don't the RS wear also? I have heard they do, along with almost all flat slide carbs, is that true?? I don't know from experience only what I have heard.

Jstewart I can't wait to hear how it runs and the differences in the mods your planing.

I was looking for long haul; with the ceramic slide wearing deeper and deeper into the plastic insert, the needle will go deeper and deeper into the emulsion tube. You would have to keep up with the mid range tuning (needle shimming). I have a WBo2 so I could see it better than with say Plug Chops.

[Joe H]

I was looking for long haul; with the ceramic slide wearing deeper and deeper into the plastic insert, the needle will go deeper and deeper into the emulsion tube. You would have to keep up with the mid range tuning (needle shimming). I have a WBo2 so I could see it better than with say Plug Chops.

The needle jet (emulsion tube) wear seems to be the biggest problem for me so far, I was puzzled at how fast it came back, Im glad I caught on to it, and most of it was thanks to this site it is a unending font of good people and info!

How do you like the WBo2, do you run it continuously or do you plug it in when tuning? It has to be a big help.
I just went through the thread you posted also, more good stuff!

Its a shame I don't ride more than I do, once upon a time I used to ride a lot, not so much anymore

[posplayr]

The needle jet (emulsion tube) wear seems to be the biggest problem for me so far, I was puzzled at how fast it came back, Im glad I caught on to it, and most of it was thanks to this site it is a unending font of good people and info!

How do you like the WBo2, do you run it continuously or do you plug it in when tuning? It has to be a big help.
I just went through the thread you posted also, more good stuff!

Its a shame I don't ride more than I do, once upon a time I used to ride a lot, not so much anymore

I went full boat on data logging as you can guess, mostly out of curiosity. I only used the WB02 during tuning. You REALLY need to put a big load on the bike to dial the main in. Otherwise it is just too dynamic and can't even settle. The 1166 has some legs so you need to find an appropriate "test track". For tuning it is certainly worth getting a dedicated WbO2 sensor and gauge. Once you get into data logging all the complexity/cost goes up. If you can get the bike up to speed, watch your speed , where you are going while watching the O2 gauges then pass on the data logging. I learned that it is important to have the main jet so that it goes rich at redline (IIRC). Anyway nothing you are going to see with plug chops.

My bike is sitting in pieces at the moment as well. Got other stuff going on.

[Joe H]

I learned that it is important to have the main jet so that it goes rich at redline (IIRC). Anyway nothing you are going to see with plug chops.

Thats interesting.
I always found it difficult to do proper main tuning on the street because I would have to find a place with a long enough straight, no people. And I was told years ago to try to find a slight uphill grade, if you can, but it all had to be long enough to stay near or at redline for 10 or more seconds to really get a the proper main jet. Just trying to hold it near redline in 4 or 5th for 10 sec is hard enough and frankly a bit dangerous on the street. Dyno tuning is the way to go but I think you need the right operator some of the kids I have seen on the dyno's here scare me worse than WOT on the street

Anyway my last go around with the 38mm cv's I ended up with 150 mains but it was weird it would stumble at 8500rpm then it would pull really hard. 145 mains the stumble wouldn't be there but it would not pull as hard or reach the speed at the same point on the run as the 150's. It also now wants the needle all the way down to the leanest setting. It made me want to try the power jet system that is on the 38's that is blocked off at the factory. I talked to Marc the owner of Factroy Pro and he said it wouldn't work anyway and I think he may know a bit more than me! Marc suggested trying a slightly larger air jet to compensate for the stumble. I may try it.

Right now Im sticking with the 145 mains, the needle is still all the way down. This winter I will rebuild, nickel plate the tubes, and have at it again next year.
I am actually hoping the nickel plating will restrict the needle jets to lean it out a bit on the needle, but the research I have done on it suggests I would need 4 or 5 mils of plating which from what I have read is a lot. And theres are small holes in the needle jet and that much plating inside those might be to much. I am willing to wreck a set of tubes for the experiment so we will see what happens when I do it!

[jstewart]

Thats interesting.
I always found it difficult to do proper main tuning on the street because I would have to find a place with a long enough straight, no people. And I was told years ago to try to find a slight uphill grade, if you can, but it all had to be long enough to stay near or at redline for 10 or more seconds to really get a the proper main jet. Just trying to hold it near redline in 4 or 5th for 10 sec is hard enough and frankly a bit dangerous on the street. Dyno tuning is the way to go but I think you need the right operator some of the kids I have seen on the dyno's here scare me worse than WOT on the street

Anyway my last go around with the 38mm cv's I ended up with 150 mains but it was weird it would stumble at 8500rpm then it would pull really hard. 145 mains the stumble wouldn't be there but it would not pull as hard or reach the speed at the same point on the run as the 150's. It also now wants the needle all the way down to the leanest setting. It made me want to try the power jet system that is on the 38's that is blocked off at the factory. I talked to Marc the owner of Factroy Pro and he said it wouldn't work anyway and I think he may know a bit more than me! Marc suggested trying a slightly larger air jet to compensate for the stumble. I may try it.

Right now Im sticking with the 145 mains, the needle is still all the way down. This winter I will rebuild, nickel plate the tubes, and have at it again next year.
I am actually hoping the nickel plating will restrict the needle jets to lean it out a bit on the needle, but the research I have done on it suggests I would need 4 or 5 mils of plating which from what I have read is a lot. And theres are small holes in the needle jet and that much plating inside those might be to much. I am willing to wreck a set of tubes for the experiment so we will see what happens when I do it!

Interesting Joe to see how the nickel plating works out. You say you don't put that many miles on your bike so other than the plating creating some other tuning problem which I doubt it may take some time to put enough miles on to determine if you helped the wear problem. Did you ask Marc at Factory Pro what he thought about nickel plating the emulsion tubes to help the wear problem?

Posplayr I am a big fan of Innovate products. I have a LM2 which I used to DL on my 08 Corvette when I was chasing a moderate throttle surge problem. I have a 03 HD Dyna superglide with a S&S 124 C.I. motor that I use a Innovate digital air fuel gauge on to tune with (no data logging) and use Dynojet's auto tune modules on my Yamaha & Honda to fine tune the FI. High tech products like Innovate make the tuning process much faster and more precise.

10 years ago I bought a Unitek A-100 elapsed timer to use on my Harley. This is a digital programmable timer that measures the ET between two programmable RPM settings with a resolution of .01 seconds. The timer is really useful in setting the main jet size based on real world conditions. When used in conjunction with the Innovate Digital A/F gauge I found the 124 C.I S&S motor produced the fastest ET's at 12.8/1 AF ratio. I haven't been able to use the A-100 timer on any other bike I have owned because all of them had stick coils except the Harley. The A-100 timer uses an inductive pickup that clips on a spark plug wire. It will work on the GS 1150.

[Joe H]

Jstewart,
I have not asked him but I should. I know Factory-Pro sells nickel plated ones for other bikes that wear the Emusion tubes very fast. When I asked him about the emulsion tubes he told me to order them from a OEM parts store.
The idea to nickel plate came from Derek who owns Moto-lab, I don't now if he has done it but when I talked to him he told me to electroless nickel plate them if I could.