78 GS750E Carb adjustments?

[Rustybux]

My son and I overhauled the carbs. The main jet was a 100 and the kit came with a 102. Cleaned and replaced everything. We noticed the little jet underneath by the float bowls had some out 5 turns and the others were 3 turns out. Can't find anything about how far to adjust so we set them at 1 1/2 turns out. Didn't idle quite so good so backed them out another 1/2 turn and it got better. Then adjused the Idle jet on the side until best idle. Before we did all that, the plugs would always be black with soot. After the carb rebuild, we rode it for about 5 miles and checked plugs. The white insulator inside is pure white and not a nice tan.
I dont see how it can be too lean. They are white like my 83 Honda Sabre. We just dont want something else to happen if it's too lean.
Did we do it alright or is something else wrong... Any help will be appreciated.
thank you

 

[Nessism]

http://www.thegsresources.com/files/vm_carb_rebuild.pdf

 

[BassCliff]

Hey howdy hey!

Hey howdy hey!

Mr. Rustybux,

Mr. Nessism has already given you the link to the VM carb rebuild. The CV carb rebuild is in the link below. You'll pay it no nevermind because you don't have CV carbs on your bike. Anyway, here is my over-the-top mega-welcome! \\/

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 here 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**********************
Here are some extra 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/
The Rice Paddy (salvage/used)
http://www.ricepaddymotorcycles.com
Ron Ayers Motorsports
http://www.ronayers.com
MR Cycles
http://www.mrcycles.com
If all else fails, try this:
http://www.used-motorcycle-parts.org/
Lots of good info/pictures here:
http://www.suzukicycles.org


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)

 

[KEITH KRAUSE]

My son and I overhauled the carbs. The main jet was a 100 and the kit came with a 102. Cleaned and replaced everything. We noticed the little jet underneath by the float bowls had some out 5 turns and the others were 3 turns out. Can't find anything about how far to adjust so we set them at 1 1/2 turns out. Didn't idle quite so good so backed them out another 1/2 turn and it got better. Then adjused the Idle jet on the side until best idle. Before we did all that, the plugs would always be black with soot. After the carb rebuild, we rode it for about 5 miles and checked plugs. The white insulator inside is pure white and not a nice tan.
I dont see how it can be too lean. They are white like my 83 Honda Sabre. We just dont want something else to happen if it's too lean.
Did we do it alright or is something else wrong... Any help will be appreciated.
thank you

If the factory main is 100, then you should re-use it. Some aftermarket jets are not precision made or may be sized using a different method. If the bike is stock, you should run 100 Mikuni in this case.
5 turns out on the pilot fuel screws is actually beyond their effective range. Maybe 3 1/2 out is their max effective range. I have to wonder why they were adjusted that far out. Even with basic intake/exhaust mods, they should be about 1 1/2 to 2 turns out. For a stock bike, 1 turn is usually very close.
Doesn't sound like you made any changes to go from black plugs to white plugs, other than those pilot fuel screw/side air screw adjustments and possibly clearing some air passages. I assume you checked the float levels too? Should be about .94" I believe?
At 5 turns out, the plugs would be blackened as long as you stayed within the pilot circuit range, about 1/5 throttle to closed. If the side air screws weren't adjusted correctly (not enough air), this would worsen the rich condition made by the rich pilot fuel screw adjustments.
If the carbs are now clean and the side air screws are adjusted using the highest rpm method (usually ending up about 1 1/2 to 1 3/4 turns out), and the pilot fuel screws are about 1 turn out, you should be close if not correct. Give the plugs several miles to color up.
Remember, closed to approx' 1/5 throttle position to test/read the plugs to check the pilot circuit...
solid 1/3 to 1/2 throttle to check the jet needles...
full throttle to check the mains.