Idle Air screw and RPM method for setting

[renobruce]

Carbs not synched.

You can't adjust an out of synch carb.

Set the mixture screws the same across the board. SYNCH THE CARBS. Do chop tests. Adjust accordingly. Synch the carbs again.

[bwringer]

Don't mean to step on toes. \\/

No offense taken! Opinions vary on this issue and many others. I think the common Uni filter elements may be more susceptible to over-oiling than the OEM elements. I've corrected over-oiled Uni filters a couple of times with excellent results, but I've never even seen an OEM filter element.

I've talked this over with Rob from CRC2, and basically he recommends installing Uni foam filter elements (at least on GS850s) with no oil or just a very light spritz of actual filter oil instead of motor oil. Even if you install the filter with no oil, it quickly becomes oily from the crankcase vapors.

Anyway, the original poster's problem is probably an air leak, since he's describing a lean condition -- an over-oiled air filter will cause a rich condition. I just mentioned air filter oiling to be complete.

I would suspect that the intake o-rings are leaking, and/or the airbox is not sealed. There may also be an exhaust leak.

As far as the idle screws, I'll confess that I've never, ever been able to discern the slightest difference in idle speed or quality while twiddling the screws individually with the bike idling. YMMV, of course -- maybe others can hear something I can't, but I've got a pretty good ear, and I can't tell any difference unless I turn them 1 or 2 turns.

Instead, I tune these by test riding to fine-tune the quality and smoothness of the off-idle transition and adjusting in 1/4 turn increments. The smoother the transition off idle, the sooner you can get back on the gas in a corner, and the smoother and faster you'll be.

And the smaller and smaller those pesky squids on CBRs and GSXRs get... :twisted:

But in order to fine-tune the idle mixture screws, everything else must be spot-on. In this case, I think the original poster has another problem casusing a lean condition that must be corrected first before he can dive into fine-tuning like this. For now, I'd set them all at 2 to 2.5 turns out and leave them there until the lean condition is handled and the carbs are synced. Mine are all set the same, and are somewhere around 2.5 turns out. (on CV carbs, in is leaner, out is richer).

Another often-neglected element of fine-tuning is float height -- I've found adjustments of 0.5 mm make a definite difference in the low-end and low midrange. Mine are set right at the minimum height noted in the manual.

[slugsride]

1. Replace old rubber (sometimes redundant...)
2. Check to see if air filter housing is sealed well.
3. Valve clearance check
4. Carb synch
5. Mixture screws

I'm sure I missed something, but 1-4 all affect how the engine responds to 5.[/quote]

Would like to add a step "3 1/2" ,compression check. If any are very low doing 4 & 5 may make things worse.

[shawzygs850]

shawzy, you said at one time "the bike was so smooth"...and I assume no other problems.
What has happened since then? What has been done? How long are we talking and did the bike sit mostly unused/unused during that time?
Is the intake and exhaust completely stock? Did you ever verify what jetting is in the carbs? Any other symptoms? High idle once warmed up?

Thanks so much to all for their feedback you guys rock. You provide the confidence I need to continue. I will replace rubber o-rings on the intake, hopefully I don't have to replace the entire boots themselves. I will also check air box sealing.

In answer to your questions Keith:

Background: the bike sat unused in a garage for about 12 months; before hitting the garage, I did not notice any drivability or running issues whatsoever (i.e. she ran and idled smooth, although granted she wasn't ridden frequently, say an hour a week). Once taken out of the garage and started the bike was in horrible running condition; after advice from this board I cleaned the carbs (remove, strip and dip); discovered air jets were quite dirty;

Once carbs cleaned and re-mounted, the bike started easily and ran wonderfully with the exception of popping symptoms as mentioned above; valve clearance checks out okay;

Bike is completely stock; jetting in carbs is also stock I assume (not sure how to tell)

I've been trying to adjust idle screws in vain if I have a vacuum leak as it buggers my plug reads no doubt. I have likely made things overly rich as a result.

I will follow slugsride steps above and post my findings.

Thanks again all!!

[slugsride]

I actually added the comp. check to "pvtschultz's" earlier post...must give proper credit.:-D

In my own nightmare, even though I probably fixed the root problem in the earlier steps, the damage had already been done (in my case carbon chips on the exhaust valve seats) and I had low compression on two cylinders.

[pvtschultz]

NP Slugs.

I too have been in the process of returning a GS850G to the road after a 7 year vacation. Money has been slow, so has my progress. But the laundry list that I posted is very true. I skipped a step or two and learned my lesson the hard way. Try skipping a step and you'll go back to number one again. For me, I'll be taking the carbs off for the 6th time tomorrow night for replacement boots (again) and new o-rings. While I'm at it, I'll actually check (set) float height since I'll have the carbs off. Then I'm hooking up the synchronizer and hopefully she'll run better. If so, new battery, hook up the front lights, and down the road I'll go. Then it is tires, registration, permit, and hopefully I'll be "done" finally...

[shawzygs850]

Boots

Need a bit more help here.

I now realize why I didn't attempt to replace intake o-rings in the first place. On pulling carbs off, it seems that my intake boots do not have a removable o-ring. The o-ring is part of the actual boot itself, all 4 boots the same. Does this sound right for an 83 gs850? Has a PO 'glued' the o-rings in place?

I attached a pic for reference. This shows the o-ring as part of the boot and also shows the area of the boot with some cracks, however I assumed that as the o-ring itself and area the carb clamps to appear just fine, cracks where they appear in the pic will not in fact cause leakage.

Before I drop $200 on boots, has anyone attempted to fix a leaky boot using a compound of some kind.

[renobruce]

The orings are on the other side of the boot....on the engine side. you have to take the boot off the engine to see them

[Nessism]

The orings are on the other side of the boot....on the engine side. you have to take the boot off the engine to see them

Yup! And based on your photo showing cracks in the boots, you need new ones.

http://www.cycleorings.com/intake.html

[shawzygs850]

Much thanks

[ironsheik]

Get 'em cheap here:

https://www.flatoutmotorcycles.com

I just did the same and man I'm happy I did.

Josh

[twistedwankel]

After fiddling with this for over a month I am ready to call it quits.

- Should I simply take the machine to a wrench and have them set idle mixture and sync carbs before loosing any more hair; I see this as giving up which kills me but I need to know when to throw in the towel, I feel like I am wasting my time at this point with fiddle here, fiddle there, and no tangible result. Cheers

If you have a "wrench" you are confident in he should be able to tell you what the problem is in short order. Put all the settings back the way they were in the first place, tell him the symptoms and let him tell you what he found. I wouldn't go "tell" him to perform anything initially. Certainly he will give you an estimate before proceeding? So you have to pay him $50 to tell you the problem. Hair is irreplacable. You're like the rest of us and all ready insane for riding a 26 year old toy. Popping on decel is definately a signal of lean mixture at speed and can hole your pistons given enough time. If I mess with a bike for one week and haven't solved the problem then I figure it's out of my league. I know I will start throwing unnecessary money at it that will not solve the original problem - only mask it further.

If you know your jets are clean and there is a proper fuel flow would be important to know before messing with 4 different idle settings. My 81 bike runs near always perfectly but sometimes will do off the wall things that only happen once - like not start! Then it won't ever happen again for years. Solution each time was a tiny shot of Ether. Go figure.

[shawzygs850]

Just an update the replacement of intake rings made a signif difference. Popping pretty much non-existent. Old rings were so hard they could not have been doing much at all, go figure.

Off to have the carbs sync'd after sealing the airbox.

Thanks to all once again

[gpfinley]

I am idling too fast

1500+

Runs fine. Just wants to idle high.
Does each carb have to be set ?