Carb help!

[rusty boltz]

Hello to anyone who reads this. I'm new (if you cant tell) and just purchased my first bike at 30 yrs old. Ironically so is the bike. Actually I purchased 2 basket case bikes and am hoping to make a decent 1 out of them. I have a 79 gs1000 and a 78 gs1000 and am wondering what are the differences of these years? The 79 was purchased without a gas tank, seat and various electrical devices but started off starting fluid when I went to look at it so I bought it. I was fortunate enough to come across the 78 which was relatively complete but had not run in years. Sooo.....I put the tank and petcock,etc. on the 79 and it fires right up but runs like poop and idles at 2 grand after warming up. It starts no problem but hardly accelerates and pops when the throttle is opened like it is starving for fuel (no power at all). I have yet to pull the plugs and the carbs look pretty clean in the bores. I am a mechanic by trade but have never dabbled in bikes before. I am wondering if the petcock is different because the carbs look different. Is there a difference in the carbs for these 2 years is it possible that the petcock for the 78 is not compatible with 79 carbs? Any help or advice is GREATLY appreciated! Thanks in advance.

[BassCliff]

Hee Haw Howdy!

Hi Mr. rusty boltz,

Most of your questions should be answered in your very own mega-welcome! \\/

Dear fellow GS rider,

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)!

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 In The Garage section via the GSR Homepage 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 if your bike uses shims for valve adjustments, send an email to Mr. Steve requesting a copy of his Excel spreadsheet that helps you keep track of clearances, shim sizes and other service work.

These are some edited quotes from one of our dear beloved gurus, Mr. bwringer, with ideas on basic 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

***********************************
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:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. 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.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.
***************************************
OEM Parts/Online Fiches:

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://denniskirk.com - Put in your bike model and see what they have.
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.
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**********************
Additional parts/info links:

GSR Forum member Mr. duaneage has great used upgraded Honda regulator/rectifiers for our bikes. Send him a PM.
New electrical parts:
http://stores.ebay.com/RMSTATOR or http://www.rmstator.com/

http://www.ricksmotorsportelectrics.com/index.php

http://www.electrosport.com/

For valve cover and breather cover gaskets, I recommend Real Gaskets (reusable silicon):
http://www.realgaskets.com
The Rice Paddy (salvage/used)
http://www.ricepaddymotorcycles.com
Carolina Cycle
http://www.carolinacycle.com
Ron Ayers Motorsports
http://www.ronayers.com
MR Cycles
http://www.mrcycles.com
Moto Grid
http://www.motogrid.com
If all else fails, try this:
http://www.used-motorcycle-parts.org/
Used bike buying checklists:

http://www.amadirectlink.com/roadride/Riderresc/checklist.asp

http://www.clarity.net/~adam/buying-bike.html
Lots of good info/pictures here:
http://www.suzukicycles.org

http://www.cyclechaos.com/wiki/Motorcycle_Wiki

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)

[Nessism]

Sounds like you tapped into a gold mine with your bike purchases.
My opinion is don't even mess with the bikes until you rebuild the carbs properly http://www.thegsresources.com/files/vm_carb_rebuild.pdf Get o-rings from cycleorings.com, including those on the rubber intake pipe boots. Build your restoration project on a solid foundation so you can move forward with confidence.

[rusty boltz]

Moving on

Thanks I am happy with my purchases so far. Today I tried adjusting the carbs but no cigar. It ran a little better by richening the mixture as far out as the screws would go. I pulled the plugs and they were almost white so I'm pretty confident that I'm not getting enough fuel. So I pulled the carbs and intake boots this afternoon. The carb bores look immaculate but I have yet to look in the float bowls so who knows what I'll find there. The intake boots and O rings were in great shape, maybe they have been replaced. I am still going to change the O rings since they are off and rebuild the carbs. I want to rebuild the carbs before I pull the valve cover to check valve clearance as the bike only has 30K miles. I know i am getting healthy spark on all 4 cylinders and the bike has been retrofitted with an electronic ignition so I am concentrating on what I suspect to be a serious fuel delivery issue. But I do have a question about the carbs. The 79 carbs do not have the round diaphragm on the top like the 78 does. Is one set of carbs better than the other? I would like to know before I order the rebuild kit so I can rebuild the better set of carbs. I am hoping that this cures the complete lack of power and popping that just frustrates the heck out of me because it's such a nice looking bike and I just want to ride it soooooo bad! Thanks again in advance for any opinions, advice or help at all!
Rusty Boltz

[tkent02]

The early 750s had VM carbs, where opening the throttle directly pulls the throttle slide up. Instant throttle response. Simple to tune and adjust.

On the 1980 and later CV carbs, opening the throttle opens a butterfly, the resulting change in airflow raises the throttle slide by a vacuum diaphragm. This takes a little time so throttle response is not as crisp, a racer might notice the difference. Originally used as a cleaner burning system to help with smog certification. They do work better if you ride in a mountainous area, as they correct for changes in elevation to some degree. They have a bigger bore so the power output is about the same, or a tad more. It is harder to get them to run right with any changes such as pod air filters or a 4-1 pipe.

The two type carbs require different heads, they are not interchangeable unless you want to get into the engine to swap heads... And the 750 engine went to a four valve head at the same time it changed to CV carbs. A 1980 or later 850 head is the same as the early 750 head except it uses CV carbs, that's the one you want if you are going to go to CVs.

[rusty boltz]

a little lost here

OK I admit I'm a little lost. Are the 750's and 1000's the same? Both of my bikes are gs1000's. Only difference is one is a 78 and one is a 79. I am restoring the 79 with parts from the 78. And the carbs are different. Is it possible that someone changed the carbs on the 78 to the newer cv style or that the bike is not what it appears to be (a gs1000)? The carbs on the 79 do not have the round diaphragms on the top that the 78 does. So what I am gathering from here and from other sources on the internet is that the round top carb is the cv type and the ones without it are the early style vm. Man this is confusing since the bike with newer style carbs is older. So tkent02, you think I should build the older vm carbs? I think that would make sense given the simplicity of them and I do like instant throttle!!! Also they are the original ones. Thanks for the input guys I'm very new to these bikes but am growing fond of them and want to ride already.

[tkent02]

OK I admit I'm a little lost. Are the 750's and 1000's the same? Both of my bikes are gs1000's. Only difference is one is a 78 and one is a 79. I am restoring the 79 with parts from the 78. And the carbs are different. Is it possible that someone changed the carbs on the 78 to the newer cv style or that the bike is not what it appears to be (a gs1000)? The carbs on the 79 do not have the round diaphragms on the top that the 78 does. So what I am gathering from here and from other sources on the internet is that the round top carb is the cv type and the ones without it are the early style vm. Man this is confusing since the bike with newer style carbs is older. So tkent02, you think I should build the older vm carbs? I think that would make sense given the simplicity of them and I do like instant throttle!!! Also they are the original ones. Thanks for the input guys I'm very new to these bikes but am growing fond of them and want to ride already.

My mistake, forget the 750-850 stuff.
Both style heads are available to fit the 1000 two valve engines.
But both the '78 and '79 should have come with vm heads, sounds like you have a later one somehow. Whoever did it probably swapped heads, or complete engines.

[rustybronco]

Man this is confusing since the bike with newer style carbs is older.

or it's not the year you think it is and or the motor was changed.
any pictures, vin?

rustyboltz, any relation to me that you know of?

[mighty13d]

post pics of the bikes and carbs. The guys on here (and gals if you will) will be able to tell you exactly what's up from the pics of them.

[rusty boltz]

Ok, I've done a little double checking and both bikes are exactly what they are titled as. Yes they are both stamped gs1000 both with build dates in 1978 and the engines look identical except the carbs. Here is a pic of the carbs on the 78. I think that these are not the right ones, but you can look and tell me what you think. A couple questions: Where is a place to get a good rebuild kit for the 79 carbs (not pictured). Also how can I post more than one pic? Does anyone have opinions on drilled rotors? My parts bike has them and they look to be almost new so I was thinking of swapping them. I would post more pics but I'm only allowed one?
Oh, and sorry rustybronco, no relation I just chose the name because living in the midwest everything I work on is held together by rusty boltz. Thanks guys/gals please let me know a good carb rebuild supplier soon so I can order and get moving on this.

[80GS750]

those are definately not the right carbs for the bike...

i would build up the vm's

i have messed with both kinds and prefer the vm's personally, easier to mess with and simpler design.

good luck with the bike, keep us updated

[northwoods]

Yes, those are definately CV carbs on the bike. Either way you can get good rebuild kits for either type from a ton of different sources out on the internet(Dennis Kirk, JCwhitney, cycleorings, mrcycle just to name a few). I found that the better kits will have the float bowl gasket, all o-rings, pilot jet, main jet, pilot breather tube all for right around 20.00 per carb.

[rustybronco]

Here is a pic of the carbs on the 78. I think that these are not the right ones, but you can look and tell me what you think. A couple questions: Where is a place to get a good rebuild kit for the 79 carbs (not pictured).

Our very own Mr. Robert Barr http://cycleorings.com/ has the o-ring kits for the carbs more than likely that will be all you need.
At the very least the bike with the cv carbs has the wrong head on it. do you see the difference on how they attach to the heads?

If you need additional photos added to your post, host them on a place like photobucket and add a link to them in your post.

[rusty boltz]

Good news and bad...

Well I'll start with the good news. I found why it was running so lean(no power,popping). While draining the gas out of the tank to clean it (just opened petcock and drained through the fuel hose into a can) I noticed there was hardly anything coming out. So I pulled the hose off the petcock and it flooded out. Turns out the cheap aftermarket clear fuel filter was as clogged as could be, I mean I almost popped an eyeball out trying to blow through it. It looked clean, couldn't see anything through the glass, but no flow in either direction. Unfortunately I did not discover this before I pulled the carbs , but if I had..... Now the bad news. Since the carbs were off I decided to go through them. Every thing was clean. No dirt, no tarnish, nothing, didn't even break a gasket. So I start pulling the jets and adjustment screws and all of them looked great, no wear no dirt, until I got to the #3 fuel mixture screw(?). Its the one that you get from under the carb on the VM carbs the bowl leaves these exposed. Anyway, I took it out (after counting how many turns in ,which was about 2.5 more than the rest but did not force it in at all) and it seems that the tip of the screw is broken off in the carb. I can see it in there but don't know what to do about it. I need to find a new adjustment screw but worse I may need a carb if I cant get the piece out. @**#!!. Any ideas would be GREATLY APPRECIATED or if your selling carb parts let me know please! Sorry for the long post and thanks to all that find interest in this thread.

[Nessism]

Use a punch and knock that tip backwards and out working from inside the carb throat.

Easiest way to get a fuel screw is to order a GS750 carb kit from Z1 Enterprises. For some reason that kit has the screw and the others don't.

Standard settings for the screws is 1 turn for the fuel screw and 1.5 for the air screw. Someone must have messed up if your fuel screw was at 2.5. Also, changing the o-rings is still a good idea if the carbs are stock; the o-rings get hard and brittle and will benefit form being properly sealed.

Hope this helps and good luck.