Lack of power, fluctuating revs and rough idling

[melanoluca]

I bought a gs850 in very sound mechanical condition around 1 month ago. The idling was unbelievably smooth; it ran like a dream on the highway and never hesitated to respond if you wanted to open it up a bit.
It only had 36000km on the clock and it sounded like new.
I sent it in to have the front folk seals done as I didn?t have the time to do it myself but while it was in I asked for replacement the filters and give it a quick once over.
Well when I got it back the idling was very rough and when I took it for a ride it was lacking power but stable until around 4000 rpm then it splutters a bit and when it gets over its spluttering the revs fluctuate high to low to high etc and you cant reach 5500rpm.
So I found out that the mechanic stole my carbs and replaced them with some that were obviously not in fantastic condition. The mechanic has since disappeared and it doesn?t look like I will be getting my carbs back any time soon. Evidently this ?mechanic? rode the bike a few times and redlined it every time before working on it. Idiot!
This is not nice to know considering I am a placid rider.
It has literally gone from sounding and feeling like new to sounding quite loose and rough i.e. tappets and timing chain.
I figured I will have to make do with what I have been left with so I have striped and cleaned the carbs and put them back. Everything looked good except for the main jet on #2 which is a bit pitted.
Even after this nothing has changed, still the same performance pattern.
I did not touch the synchronizing screws and suspect that this could be part of the problem.
1) Could anyone tell me how to go about synchronizing these carbs without the right equipment?
2) If I drop the needle down a notch would this help? They are all set on the first notch from the point.
3) Are there any other possibilities besides the carbs for the cause of this problem?
I am looking for some solid advice as to how I am going to solve this problem.
Thanks

 

[BassCliff]

Hey howdy hey!

Hey howdy hey!

Mr. melanoluca,

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. I would pay attention to the parts concernnig O-rnigs, leaks in the air intake system, carb cleaning, etc. I'm sorry to hear about your sorry mechanic. That's another reason why I'm trying to learn all this stuff, so I can do it myself.

***********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)

 

[Pete Logan]

It has literally gone from sounding and feeling like new to sounding quite loose and rough i.e. tappets and timing chain.

Have you checked the serial number ? It has been known for entire engines to be swapped. Sorry for the pessimism

 

[trippivot]

sell it and start over.

at very least put the bike in the shop manager/owner's lap. he is responsible for his employees actions... period.

get a lawyer! that hack had to give information to get that job.

a bad motorcycle mechanic can get you KILLED!! stealing is really bad but there are worse possibilities.

this is a long expensive road back if you have zero experience in carb tunning .
so sorry for your trouble.

 

[spyug]

Sorry to hear of your bad luck with this situation.

Why did you not take it right back to the shop and how did you find out that the carbs had been switched?

As Trip says, you should be going after the shop owner....was he the mechanic? In all jurisdictions that I know of the shop owner is responsible for the work done by his employees. If carbs have been switched that is theft and if you paid to have it done its also fraud. I'm sure the shop owner wouldn't want to be talking to the police and facing potential charges.

If you can't or won't deal with this in a legal manner then get rid of the bike. There is no doubt from what you say that more damage has been done and or the whole engine was swapped for a bad one. Don't be pouring good money after bad. If you must spend more spend it on a good lawyer.

If I were you I'd be positively vibrating with rage and willing to do anything legal to get some recompense .

Good luck with this.
Spyug.

 

[melanoluca]

owner and mechanic gone

owner and mechanic gone

Hi Guys
Yea! trust me if a had half the chance i would have dumped the bike back with them and smashed both of their faces in. These guys are long gone. doors are locked and the shop is empty almost over night. i got off lightly, one guy lost his whole bike. he left it with them while he went on holiday. I do have a case pending but obviously they will have to be found first which i will be more than glad to see.
Thanks guys

 

[Pete Logan]

Hi Guys
Yea! trust me if a had half the chance i would have dumped the bike back with them and smashed both of their faces in. These guys are long gone. doors are locked and the shop is empty almost over night. i got off lightly, one guy lost his whole bike. he left it with them while he went on holiday. I do have a case pending but obviously they will have to be found first which i will be more than glad to see.
Thanks guys

That being the case, I suggest we all start working on getting this bike going right again.

Reality may not be nice, but it's where we have to go from.

Well when I got it back the idling was very rough and when I took it for a ride it was lacking power but stable until around 4000 rpm then it splutters a bit and when it gets over its spluttering the revs fluctuate high to low to high etc and you cant reach 5000rpm.

I'm no expert, and there are people here who are, but that sounds to me like an air leak on the intake side.

Let's get this one back up, guys.

 

[hampshirehog]

When you split the carbs did you check that the numbers on the jets are what they are supposed to be? If you're running stock air box they could be set up for pods. From your description of the needle setting, if I understand it correctly, it looks like they may be.

You don't say whether these are VMs or CV carbs. They have (obvious) different modes of operation and settings etc. It is also helpful to understand how the bike is performing at different throttle openings (idle, 1/8, 1/4, 1/2, 3/4 and WOT) - tells you more than the revs.

All the rubber seals and O rings have to be in A1 shape or you'll be sucking air - another place to start looking.

You can't synchronize the carbs accurately enough without the right kit, though there are instructions on here on how to make your own carb balancer. - though the balancers are cheap enough and essential tools so I'd buy one if I were you. Charge $10 a time checking your mates and you'll get you money back!

I suspect from your symptoms / story that it is the carbs that are messed up and that's certainly the best place to start looking. Even if the bloke thrashed the pants off it, the 850 is a tough old bird and capable of surviving pretty severe abuse. (I've always thought of the red line as for information only on a GS!)

There are good tutorials on here to follow and loads of help available. It's an easy job to tackle - just has to be done with absolute cleanliness and care.

 

[duaneage]

They may not be the correct size even. I think yours had 34 mm carbs, the 550-750 bikes used 32. After that we need to see what size jets and rods they have. You're going to have to open up one carb at least and see.

That really sucks, is there anything the law is going to do or will you have to suck it up?

 

[melanoluca]

Plenty of space to hide

Plenty of space to hide

Howzit Duaneage
Yes there is a lot the law can and will do once they get hold of these dudes. South africa is a big place and its not difficult for guys like this to lay low for a long long time. Sadly the law enforcement here lacks manpower and is over run with crime of all kinds with all races.
These are cv carbs 32mm ID does that sound right. What are the numbers supposed to be on the jets if these are the right carbs?

 

[Steve]

They may not be the correct size even. I think yours had 34 mm carbs, the 550-750 bikes used 32.

If he has CV carbs, they would be 32s. The 34s did not turn up until you got a 1000 cc to suck through them. 8-[


.

 

[waterman]

Wow. I really feel for your situation. I have a brother in Kenya currently and he tells me how crazy things can be.

I would try to verify that the carbs the mechanic put on your bike are the correct ones for it. Even then, I would be hesitant to go about rebuilding since you don't know their history. I would check ebay (again taking into consideration your location, shipping maybe cost prohibitive) and try to find a set to rework. Maybe someone on the board has a set they could send you. Please tell us what year your 850g is, this will help determine which set of carbs it requires.

I would tend to agree with the others that unless the mechanic drained the oil or left it idling for hours, he probably didn't harm the motor too much. These motors will survive a fair amount of abuse, especially if only a hundred kilometers or so. Hopefully, he didn't remove and replace motor along with carbs. One way to check would be for rounded nuts on motor mounting bolts or where the shaft drive connects to motor (under plastic cover). As heavy and cumbersome as the motor is, I would doubt it, but with these idiotic mechanics... Good luck, keep us posted on your progress.

 

[Steve]

These are cv carbs 32mm ID does that sound right. What are the numbers supposed to be on the jets if these are the right carbs?

I have 115 main jets in mine, and according to the carb sticky at the top of the forum, that appears to be correct.

Carb Sticky
.

 

[Dave8338]

I'de want to verify that the engine is yours and not an entire lung transplant! :shock: Then, there are plenty of tests to run, to ensure that it is even worth the work/effort.