Gs850 Carbs.

[Chris Bohane]

I have just bought a set of CV carbs for my GS850. I am running a standard air box.

Could someone please explain the process of "setting up" the carbs?
Do I fit the carbs to the engine side first or to the air box first?
You might have realised by now that this is my first time!

Thanks,
Chris

[chef1366]

What year is your bike?
Did you have carbs on the bike before the purchase?
Are you referring to removing the carbs or installing?
You need to make sure the jetting is right for your bike before installing the carbs.

[Chris Bohane]

What year is your bike?
Did you have carbs on the bike before the purchase?
Are you referring to removing the carbs or installing?
You need to make sure the jetting is right for your bike before installing the carbs.

Thanks for the quick response.
The engine is a 1979 which had slide carbs originally......but I fitted a new head from a 1980 bike so I needed a set of CV carbs from a 1980 bike.......it's a long story!!!!
So, I have a '79 engine with a '80 top end complete with new inlet manifolds to suit. I also have an air box from the 1980 bike.
The CV carbs came from a 1980 bike which was broken for spares. It was running before it was damaged in an accident.
So, the carbs match the head and air box what I need to know is, what do I do next regardig the instalation and set up.

Thanks again
Chris

[bwringer]

Where are you? There might be a GS-er in your town who could help out.

Step one would be to completely disassemble and clean the carbs, using the Carb Cleanup Series as your guide:

http://thegsresources.com/gs_carbrebuild.htm

Don't be afraid -- it's easier than it looks!

Reassemble with new float bowl gaskets and using new o-rings from Robert Barr.
O-ring kits: http://cycleorings.com/
Float Bowl Gaskets: http://www.crc2onlinecatalog.com/ or OEM from any Suzuki dealer. CRC2 will also have float needles if you need them.

Make sure you set the float height correctly as outlined in the Carb Cleanup Series.

Do NOT waste your money on carb rebuild kits. Clean and re-use the original jets, etc.

If the engine/carb boots are at all stiff, replace them. Also make sure that you have decently new o-rings under the boots.

[sissonk]

I have a GS850 also a 81 . set the carbs in position and fit the cables before you push them into the engine . make sure all 4 clamps are in right position before you put the carbs on. I use a long piece of wood to pry them gently into the 4 rubber manifolds and put silicon grease on them also. make sure the fuel line and vac line to the petcock are on and the two vent tubes . Them put the airbox in -easier from the left side - I have always found that I had to get all 4 of the rubber couplings onto carbs at the same time. fiddly job , make sure the 4 clamps are in the right position so you can screw them tight.
have fun

[Chris Bohane]

GS850 Carbs

Great advice gentlemen, thank you.
Could you go further and explain "bench sync" the carbs before fitting?
Thanks
Chris

[bwringer]

Bench syncing simply involves using a small drill bit or piece of rod to set the butterflys so they all open roughly together. The procedure is explained in detail in the manual. Basically, you start with the #3 carb and open the throttle until the drill bit just falls out. Then use the sync adjusters to set all the other carbs to the same opening, using the drill bit as a gauge -- set the adjuster to make the carb opening a little less, insert the drill bit or rod, then turn the adjuster until it falls out.

This is a very approximate adjustment that will enable you to get the bike started and do a proper vacuum sync.

One other common problem you should correct is that the airbox must be sealed tight to work correctly. In other words, air should only be able to enter the airbox via the snorkel on the back and the vent holes in the bottom. You MUST seal the side covers of the airbox with some sort of foam rubber -- most people use commonly available self-adhesive weatherstripping, and glue the edges together with yellow "gorilla snot" weatherstripping adhesive. The covers fit tightly, but they must be have airtight foam gaskets or the bike will run like crap.

You also have to make sure the top of the air filter is properly sealed in the same way. I usually glue foam weatherstripping to the top of the air filter to replace the crumbling or missing original seal. Air should only be able to get to the top half of the airbox through the foam filter. The weatherstripping on the top of the filter should form an airtight seal.

Lastly, the foam air filter element should be VERY lightly oiled. It's common to find these soaked with far too much oil. If you get a new Uni air filter element, a light spritz around the outside with spray air filter oil is all that's needed. If you've already soaked it with motor oil, use dish soap and warm water to wash most of it out. Make sure the filter is completely dry (no shortcuts -- it needs to dry overnight) before reinstalling.

Older foam air filter elements tend to swell over the years and restrict. If this happens, you can use sharp scissors to cut about 1/2 inch off all the way around and restore air flow. If the filter element is getting more difficult to stuff into the frame, you might need to get a new one or cut a bit off yours. Don't cut off so much that there are gaps where unfiltered air can get through.

Sealing the airbox is a ritual every GS owner must go through.

[Chris Bohane]

bwringer.....thank you very much for the advice. I appreciate the time and trouble you have taken to reply.
I am waiting for some rubbers to arrive from Suzuki then I can get on and fit the carbs.
Should be ready for next weekend I hope!
Regards,
Chris

[knotzilla]

I also found that appling silicone lubricant to the outside dia of the carbs which slip into the intake boots on the engine side and then heating up the boots a bit with a heat gun helps alot if the boots are on the hard side or if installing the carbs in a cold shed. Ted