VM29 specs, manual, tuning tips for GS750/1000???

[Chuck78]

Alrighty well I guess I'll look for a spare vm29 smoothbore float bowl or drain plug to drill & tap a tiny hose barb into unless I can find a fuel level adapter. I have replacement needle valves for good measure, but am going to stay with the stock seats for now.

[chuck hahn]

#30 on the parts list and shows its still available from Sudco You have to call them for prices and be aware they will ask if your a dealer. I tell them no and they inform you they charge an extra 5 bucks if your not a dealer. Well if you need it you need it..right???

http://www.sudco.com/Catalog37Digital/index.html#/173/zoomed

Wont need to add a barb for the tube. just measure the OD and drill the hole a few thousands under size. Poke the end of the tube thru with a small screw driver or something. Being a little under size should seal the tube to the plug

[Spyderman]

Also, why don't smoothbores have overflows???

And who makes a fuel level tube adapter for the float bowl drain/main jet plugs, to measure actual fuel level with a transparent u-tube??

check Z1 they have lots of parts for smoothies and i have seen that they have the fuel level adapter for the drain plug

[steve murdoch]

Website says currently out of stock, but a phone call might have different info.

http://www.z1enterprises.com/ItemDetails.aspx?itemDescription=Fuel+Level+Gauge+Tool+for+VM29+smoothbore+carbs&item=ZSM-VM29FT

[Chuck78]

Any idea if the VM33 float bowl drain plug is the same thread/size as the VM29? I found a spare vm33 drain plug. Z1 is sold out of the fuel level adapters and waiting for more to be manufactured

[chuck hahn]

Try it in a 29

[Chuck78]

Jet sizing???

So I have the VM29 A7 for Kawasaki's, with the 1.5 slide vs the 2.0 that comes with the VM29-A12 GS750/1000 version. On stock GS's, the earliest GS750B's up to engine #11,787 came with 2.5 slide cutaways, but the rest of the 750/850/1000 VM26's came with 1.5's stock. I wonder if this will have any ill effect on low throttle openings, and I wonder why the difference between Kawasaki & GS versions? Maybe the stock parts on the smoothies were intended for stock bike tune, where the Suzuki's had drastically more radical cams than stock kz's & CB's????

[Chuck78]

Also the main air jets are smaller (.8 or .9) than the gs1000 carbs (1.5). The 750 vm26 carbs run .8 to 1.1. The 750 carbs needed a 112.5 main on my 920cc 10:1 w/750 cams. The 1000 carbs with larger main air jets needed a 117.5 main to achieve identical AFR O2 readings.

The larger venturi is going to require larger mains than a 26, however, due to lower velocity using the same slightly worked head & gs750 cams. I'm expecting that I may need a 115-120 main. Any ideas?

Hoping the standard pilot of 25 on all models will do the trick, if that is what is in them still! It was tuned for an 860cc 750 with stock cams, large ovalnk&n pods, and a kerker or similar 4:1

I read

[Chuck78]

Try it in a 29

It's on eBay that I found a spare smoothbore drain plug, listed for a vm33 smoothbore. Hard to try it on mine without purchasing! There's an entire vm29 bowl&drain listed for $65... Trying not to spend that much though.

[Chuck78]

Interesting... A 1979 CycleWorld article said that a stock GS engine'd race bike went from 12.72 @103.8mph 1/4 mile to 12.19@108.95mph with Yoshi hand bent unmuffled race pipe and VM29's (I assume with velocity stacks), but vm26's jetted for the yoshi race pipe, the best time they could turn was 12.88@104.4mph... So you definitely have solid evidence to upgrade to smoothbores if running a free flow performance exhaust, or else you forgo big performance gains and actually lose performance at the benefit of the open exhaust sound... Interesting. Likely due to drastic loss in mid torque, where the smoothbore 29's definitely are helping build high end HP.

Point of this was that a stock gs750 engine ran 117.5 mains on this race bike with yoshi pipe. This 860 was running nylon 110 mains, so I am guessing the 920 might need somewhere in that mid 1-teens range. Any better opinions?

[Agemax]

the 29 and 33 smoothies share the same bowl and drain plug. instead of asking loads of theoretical jetting questions, just wait till you bolt them on, see how it runs and adjust to suit from there. you will never get it right by guessing

[Chuck78]

Just trying to get it closest the first try, that's all. Wrenching time is very limited.

Thanks for the tip on the vm29 vs vm33 smoothbore drain plugs.

[Spyderman]

as for your question about the 1.5 VS 2.0 cut away what it does is the 2 increases the amount of air so the it will make mixture leaner on the 1/8 to 1/4 throttle setting
the 1.5 will make the 1/8 to 1/4 throttle position a little richer
The slide valve affects carburetion between 1/8 thru 1/2 throttle. It especially affects it between 1/8 and 1/4 and has a lesser affect up to 1/2. The slides come in various sizes and the size is determined by how much is cutaway from the backside of it, The larger the cutaway, the leaner the mixture (since more air is allowed through it) and the smaller the cutaway, the richer the mixture will be. Throttle valves have numbers on them that explains how much the cutaway is. If there is a 3 stamped into the slide, it has a 3.0mm cutaway, while a 1 will have a 1.0mm cutaway will be richer than a 3mm cutaway.

so i wouldn't really worry about the cutaway too much because it's affected by the pilot circuit's air mixture screw as well and can usually be compensated for with small adjustments to the needle circuit and the pilot circuit

hope that helps

[Chuck78]

Well... I guess I don't have to worry about tuning my smoothbores anymore. some very very cruel person that knows a whole lot about 1970's Kawasaki & Suzuki big 4 cyl superbikes spotted my GS in the back of my truck loaded, parked right next to my house where it has been since I returned from vacation, broke my wrist and didn't have any help to unload it!

this morning I went out to my truck and noticed my carbs and air filters were gone! Geez, of all the luck, someone was able to distinguish that I did not have stock VM26 carbs on my bike even though they look nearly identical, the thieves saw the big hex quick change main jet drain plugs and knew they could use those very sought after & rare carbs on their Z1/KZ1000 most likely, lots of those in this part of town, or at least knew they were very valuable carbs worth the 3 minutes of removal to steal.

needless to say, I am heartbroken over the loss of a crucial part of my bike that was almost completely set up exactly how I have wanted it for years.I was going to put CR 31 smooth bores on the big bore GS 425 project, then I thought if I get this Rickman frame, maybe I would not hassle around with refurbishing an old worn set of VM 29's again, & just go with a pricey new set of Keihin CR Specials... well now it looks like I may need two sets of 4 cylinder CR's, and one set for the twin. better start doing lots of side jobs. majorly bummed out here in Columbus Ohio.

[storm 64]

Wow Chuck, I'm sorry to hear about your carburetors that just sucks! I bet they turn up somewhere, I'll keep my eyes open for them. I bet someone local took them. Someone that saw your motorcycle before and knew what you had. Them Bastards! Next time you need a hand unloading your motorcycle or anything like that let me know. My brother doesn't live to far from you, I know he'd help you out. You take it easy my friend.