cv carbs

[litshoot]

i have a 77 gs750. it has vm carbs. i was wondering if a set of 82ish 850 cv carbs would work with my bike both size and flow. i'm not a big fan of the vm just because if i hit throttle quick it bogs. if anyone know or has little hints for me to get rid of the bogging. its at different rpms from low to high if i twist quick. i've already checked for vacuum leaks, and not ready to adjust the loose nut behind the wheel so any help would be useful.

[Steve]

If you want to go with CV carbs, you will have to change the head, too. If you want to keep the stock airbox, you will have to change that, too, or go to pods.

The bogging on sudden throttle application is one reason the bike manufacturers went to CV carbs. When you open the throttle suddenly, you destroy the vacuum that is pulling air through the carbs, so no gas gets sucked in. No gas, no air,...no power. I know you said you are not ready to adjust the nut that holds the handlebars, but one solution is to modify your riding technique so that you roll it on quickly, rather than snapping open. With your 30-year-old bike, it is likely that the o-rings in the intake tubes need to be replaced. You can get them from Cycle o-rings. The owner of the site is a member here. There are also good things to be said about cleaning, synching and tweaking the carbs so they work as well as they should.


.

[chef1366]

Or get some VM carbs with a accelerater pump.

[Dave8338]

Or get some VM carbs with a accelerater pump.

Didn't Yamaha use them on the 750+ Maxim bikes?

[litshoot]

i was wondering where i could find a set that would hook up with accelerator pumps installed or is their a way to modify the current ones and add them. any help could be great.

[BassCliff]

Hey howdy hey!

Mr. litshoot,

Please forgive me if I haven't given you the "official" unofficial welcome. BTW, did you get your petcock fixed?

Let it be known that on this day you are cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Further let it be known that your good standing can be improved with pictures (not you, your bike)! :grin:

Perhaps you've already seen these, but I like to remind all the new members. In addition to the carb rebuild series, I recommend visiting the garage section via the GSR Hompage and check out the Stator Papers. There's also a lot of great information in the Old Q&A section. I have some documentation on my little BikeCliff website to help get you familiar with doing routine maintenance tasks (note that it is 850G-specific but many tasks are common to all GS bikes). Other "user contributed" informational sites include those of Mr. bwringer, Mr. tfb and Mr. robertbarr.

And here are some quotes from one of our dear beloved gurus, Mr. bwringer, with ideas on basic maintenance needs (depending on initial condition), parts, and accessories.

***********Quoted from Mr. bwringer************
Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:
http://bwringer.com/gs/intakeorings.html

Here's an overview of what happens with this particular problem:
http://cycleorings.com/intake.html

You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.

And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com

Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:
http://thegsresources.com/gs_carbrebuild.htm
*************End Quote*************
**********<quote Mr. bwringer>**********
Every GS850 has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting.

It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years.

It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

Intake O-rings (install NEW OEM or Viton only - common nitrile o-rings will quickly deteriorate from heat)

Intake Boots (install NEW -- these cannot be repaired)

Valve clearances (more important than most people think)

Carb/airbox boots

Airbox sealing

Air filter sealing

Petcock (install a NEW one)

On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)

On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.

Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.
**********<end quote>**********
***********Quoted from Mr. bwringer***************
http://denniskirk.com
Put in your bike model and see what they have.

I would definitely double and triple the recommendations to use Cycle Recycle II and Z1 Enterprises as much as possible. These guys are priceless resources. Z1 tends to have slightly better prices, CRC2 has a wider range of goodies available. If you're near Indy and can bring in an old part to match, CRC2 has a vast inventory of used parts.

http://oldbikebarn.com seems to be slowly regaining a decent reputation, but it's still caveat emptor. They don't have anything you can't get elsewhere at a better price anyway.

OEM Parts/Online Fiches:

http://www.babbittsonline.com/
Decent parts prices. Spendy shipping. Don't give you part numbers at all. Useful cross-reference if you obtain a part number elsewhere. Efficient service.

http://bikebandit.com
Fastest. Middlin' prices. Uses their own parts numbering system to obfuscate price comparisons -- can be very confusing for large orders. Cheapest shipping, so total cost usually isn't too bad.

http://flatoutmotorcycles.com
Slow. Cheapest parts prices, crazy shipping costs. Don't expect progress updates or much communication. Real Suzuki part numbers.

http://alpha-sports.com
Exorbitant parts prices. Different type of fiche interface that's quite useful at times, especially with superceded part numbers. Real parts numbers. Shipping cost and speed unknown due to insane, unholy pricing.

Stainless Bolts, Viton o-rings, metric taps, dies, assorted hard-to-find supplies and materials, etc.:
http://mcmaster.com
Fast, cheap shipping, good prices. No order minimum, but many items like bolts come in packs of 25 or 50. Excellent resource.

http://motorcycleseatcovers.com
Great quality, perfect fit (on original seat foam), and available for pretty much every bike ever made. Avoid the textured vinyl -- it's perforated.

http://newenough.com
You DO have riding gear, don't you? Great clearances, always outstanding prices and impeccable service.
***************End Quote**********************

Here are a few extra links:

Cycle-Re-Cycle Part 2
http://crc2onlinecatalog.com/

The ever popular Z1 Enterprises
http://www.z1enterprises.com

The Rice Paddy (salvage/used)
http://www.ricepaddymotorcycles.com

Ron Ayers Motorsports
http://www.ronayers.com

Thanks for joining us. Keep us informed of your progress. There's lots of good folk with good experience here.

Thank you for your indulgence,

BassCliff
(The unofficial GSR greeter)

[chef1366]

Get some 32mm Mikuni flatsides.