81 GS1100 with 29 smoothbores.

[Don R]

I'm still getting to know this bike, I put a wide band O2 gauge in it and have been monitoring the air/fuel ratios. I dropped the mains from 125 to 120 and it seems better. I may need to drop the pilots a size and check the needle position. I also ordered a new set of pod filters from APE, the old K&N's were so hard and shrunken I couldn't get them back on even after trying to soften the rubber with oil of wintergreen. I waited a month for Jegs to get me a set of K&N oval filters and gave up.
What's the consensus on running 29's on a 4 valve 1100? I'm thinking about buying a set of 36 Mikuni flat slides, or even going back to all original. The motor doesn't seem to be modified inside.

 

[Nessism]

I can't think of any reason not to use VM29's. You may be able to get more power with something bigger, but unless you are racing, I don't think it's worth starting over.

 

[rphillips]

Back in the day, a few tried the 29's on 4V Gs1100's and saw no or minimal improvement over the stock 34 CV's. Around here, the 33 smooth bores were being put on the GS1100's and replacing the fuel inj. on the Kawa. GPZ 1100's.

 

[Nessism]

Back in the day, a few tried the 29's on 4V Gs1100's and saw no or minimal improvement over the stock 34 CV's. Around here, the 33 smooth bores were being put on the GS1100's and replacing the fuel inj. on the Kawa. GPZ 1100's.

I'm not an expert on the subject, but my understanding is that the 33's don't idle particularly well by design.

What I do know is that VM29's are worth a ton of money these days. A person could sell them and buy a brand new set of RS36's, and maybe even have money left over.

 

[Don R]

Selling the 29's and buying flat slides is my plan B. I don't know anything about the bike except the PO lost one like it in a divorce and bought this one as a replacement. The shop owner was pressured to sell it and wouldn't give the po any information, I expected to find a big bore kit or cams. I read that the 29's slides on a 16V Suzuki should have the 2.0 cutaways. Honda and Kawasaki need the 1.5.
A local that ran these bikes back in the day said he tried 33's, couldn't get them right and went back to 29's since he wasn't redlining it anyway. He's tweaking on a V Max now.

 

[GregT]

Nessism's last post is correct. Sell the 29's and go RS36. Neither the 29's or the 33 smoothbores are good street carbs. RS36's will outperform them,be easier to set up and probably more economical too. I've run smoothbores in both sizes on several bikes and RS's of various sizes too. The RS is a much better carb.

 

[Don R]

I've been searching but came up short, can anyone tell me how can I tell if these 29's have the 1.5 or 2.0 cutaways? Is the number external somewhere or do I need to remove a slide?

 

[Nessism]

Remove the slide. The marking is on the top.

 

[rphillips]

When we think 29's, 33's, or 36 flat slides we're usually thinking performance. Not knowing what your ideas are, for a great running, no tuning, maintenance free rarely needs anything fuel system it will hard to beat the OEM CV 34, or a set of CV 36's from a GS1150. I ran a set of them on my GS1100 and don't remember having to modify anything.

 

[Don R]

Early on into this adventure I read that the stock carbs didn't play well with modifications. Not knowing for sure what's inside the motor but also seeing a Kerker header I assumed there was a reason the VM29 carbs are there. Now that I've seen the cams they appear stock. When I re-check the valve lash I'll measure them.
I put the stock airbox system back on my KZ1000 and improved it a ton so I can see the advantage of that. I'm still learning this bike so that's why I'm asking the questions.
Either way, I'm planning to list the 29's but want to know exactly what I'm selling, I'd rather know if they are correct for a Suzuki than sell them to someone and find out later they belong on a KZ or CB.
The GS will be attending the drag races in the trailer along with our dragster. I hope to get comfortable enough to make a few time runs before I'm too old and my health (common sense) keeps me off of it. There's a retro 1124cc turbo Honda going together in the shop but this bike could be quicker.
I appreciate all of the suggestions and information. Since it's race season the project may slow down a little, I'll be seeing some of the best bike bracket racers in the world, and am seeing one of them selling GS parts so who knows?

 

[rphillips]

Just my opinion, for a GS1100 to beat any 1124 Turbo (if tuned anywhere near right) this GS is gon'na need a bunch of performance upgrades... But good luck...... Hey, I don't know how to do links, but just found a thread here at the GSR from back in 2014 titled GS1100e smoothbore/slingshot carb advise that has some interesting stuff in it. Some disagreements, but possibly get some idea's.

 

[Don R]

Well, this particular 1124 is a bored and stroked SOHC (750) Honda, the heads are primitive compared to even 10 year newer bikes. It's a nostalgia build.

 

[Don R]

Today I rode with the wide band O2 sensor and again the A/F ratio was nearly 2 points different depending on if I was going into or with the wind. With the wind from the front-left it read 12.2 to 12.5-1 when I turned around and rode with the wind at my right rear the ratio got over 14-1. I can only attribute it to the effect of the wind on the pod filters on the 29's. I can see where the factory airbox is a solid design. Next, I may make a removable wind shield just as a test.

 

[grcamna2]

Don,this is Bill(from sohc4)and I think a set of Mikuni RS34's would fit your application for street and some strip use very nice.

 

[pdqford]

Today I rode with the wide band O2 sensor and again the A/F ratio was nearly 2 points different depending on if I was going into or with the wind. .

I’m no carb guru, but I would suspect the needles would be higher into the wind than with the wind.

 

[Don R]

I rode it today and got some mid range A/F numbers. It's still fat in the middle although a bit better with the 120 jets than the 125's. I'm going to pull the carbs and drop the needles a notch or two. While apart, I'll catalog the slide number, jet needle and pilot jet sizes.
I went to the industrial park by my buddy's dyno shop, where I keep my hot rod stored in winter, there is a few block long street with no driveways or side streets, I hammered the gs a little and was amazed at the sound of the Kerker echoing off of the warehouse buildings.

 

[Don R]

I went to the storage unit and traded a Honda for the GS. The petcock stuck or the inline filter must have plugged, It was extremely lean so I just got it home. Later I tried it again and it ran fine, still too rich though. I pulled the carbs and checked the slow jets, I ordered the next smaller two sizes before I noticed the slides are 1.5's, everything I've read says the Suzuki wants 2.0's. which I can buy for $75 each. That's a deal breaker so I'm going to list the smoothbores for sale and hopefully buy a set of 36's. I did buy a set of Sudco carb adapters to put the 29's on a CB750, they may be the next to last set in captivity. Z1 enterprises has one more set.

 

[Don R]

I got the new jets from Z1 ent. right after I found a nice box of them in my brothers tool box, I dropped the mains and pilots both 2 sizes and left the 1 size over air jets. It's a happy GS1100 now, the air fuel ratio never got fatter than 12-1. I wrote down the Greg Cope jet suggestions from the APE web site.
I'll likely keep the 29's on it unless someone wants them badly enough to pay close to what they are selling for. I did finally find and buy a set of the intake rubbers that fit the Kawasaki - Suzuki carb spread to a cb750 SOHC engine.

 

[Don R]

Apparently when it went lean leaving storage it was out of gas, When I got home and it ran good I must have slopped some from the right side over to the left side. When I left tonight it ran out and picked up when I got the petcock onto reserve. No odometer and I didn't think the gauge was on empty yet.
Anyway, I'm getting a kick out of the afr meter. I can see the fat area of the fuel metering caused by the 1.5 slides. It certainly runs better than it did going full rich. Still no air filters from APE. Jegs held my money for a month with no filters.
A fill-up from reserve was 3 gallons. I used 5 gallons of evaporust in it. so reserve is pretty deep.

 

[Grimly]

Still no air filters from APE. Jegs held my money for a month with no filters.

Might be something to do with the passing of APE's founder.

A fill-up from reserve was 3 gallons.
I used 5 gallons of evaporust in it. so reserve is pretty deep.

Reserve should only be about a gallon or so. I had a running-out symptom on mine long before it went onto reserve, turned out to be varnish on the sieve filter on top of the pick-up pipe.