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Just picked up an 850G - High Idle problem

  • Thread starter Thread starter Brent099
  • Start date Start date
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Brent099

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My dad and I just picked up a 1980 850G with 8k miles on the odometer. We don't know a whole lot about the history of the bike, except that the engine has been replaced. So far we have discovered a replacement r/r, an aftermarket petcock, and a large foam sponge jammed inside the air box :?.
The bike starts fine now that it has a new battery and the engine seems very smooth.

The first problem we encountered was that the idle was changing speeds when the handle bars were turned in either direction. Looks like the PO had over tightened the throttle cable at the grip and was using that to keep the bike idling. We adjusted that to give it some slack. Fixed that problem, but then the bike wouldn't idle.

Found that the idle screw was unscrewed past the point where the threads actually catch, so it was just moving in and out freely by about 1/4 of an inch (it actually looks like he tried to use some sort of gum/goop to hold it in position). Screwing it in just enough that the threads hold it results in a high idle, at least 2k rpm (just guessing here since the tach is broken). The idle doesn't seem to change at all as the engine warms up.

This is our first time working on a Suzuki, so we're not really sure what to look for.
So where should we start in trying to bring the idle down to normal?

Thanks for any suggestions.
 
Well, you need a couple of basic things

1. Adjust the valves
2. Check the intake boots for hardness or cracking
3. Change the oil
4. The high idle may be caused by a number of things. Check the mixture screws and set about 1 1/2 turn out
5. But it's highly likely the high idle is just caused by a misrouted or incorrect cable. Pull the tank, take it off at the carbs and route it thru the head light ear and down the right side (as you sit on the bilke) The cable should have adjusters at both ends, make sure it's got some slack in it. And lube it

Does the bike have the stock handlebars on it??
 
Be prepared to spend the time giving your 850 a through check out.
Firstly, buy a Clymer,Haynes, or Suzuki service manual. This will give you specifications and advice on overhaul and tuning prodeedures.
The PO has obviously taken some extreme measures to keep your engine running. The slab of foam in the airbox and the botched up idle screw are good examples. These engines require a fully sealed intake system. Check the seals around the chromed end covers on the airbox. They swell with age and don't seal properly. Many owners replace the rubber seals with weather stipping.
The high idle rpm is possibly caused by incorrect cable routing and lengths, but may also be due to incorrect carb synchronisation or jetting. It may pay you to pull the carbs and do a manual carb sync.
The fact that another 850 engine has been installed after only 8k miles on the clock, is also suspicious.
 
Thanks for the replies.
The bike came with a Clymer manual.
The throttle cable is routed correctly and it does have some slack in it. I believe the bike does have the stock handlebars.
The intake boots look to be in good condition.

I noticed that there is no vacuum line going from the #2 carb to the petcock, instead the PO had placed a rubber cap over the nipple on the carb. Replacing that cap with something a bit more airtight seemed to lower the rpm a little. Tried adjusting the mixture screws some, but it didn't make much of a difference.

I'm starting to wonder if the idle screw is the main cause of our problems.
Is it normal when adjusting the idle screw for it to have an initial area that catches the threads, then about 1/2 inch of dead space, and then a second section where it starts threading again?
 
Brent099 said:
Thanks for the replies.
The bike came with a Clymer manual.
The throttle cable is routed correctly and it does have some slack in it. I believe the bike does have the stock handlebars.
The intake boots look to be in good condition.

I noticed that there is no vacuum line going from the #2 carb to the petcock, instead the PO had placed a rubber cap over the nipple on the carb. Replacing that cap with something a bit more airtight seemed to lower the rpm a little. Tried adjusting the mixture screws some, but it didn't make much of a difference.

I'm starting to wonder if the idle screw is the main cause of our problems.
Is it normal when adjusting the idle screw for it to have an initial area that catches the threads, then about 1/2 inch of dead space, and then a second section where it starts threading again?
Click to expand...

The idle adjustment screw should be completely threaded from the contact point to just short of the hand piece. That's probably the cause of your adjustment woes. It's something that would rarely be experienced on this forum, mainly because the PO has deliberately done this to compensate for other bad tuning practises. Replace it and start adjusting.
Good luck.
 
Alright, I just pulled the screw out and the threading on the screw itself looks normal. So I guess the problem lies in the carb assembly where it screws in.
Thanks for the help 49er
 
Sounds familiar

Sounds familiar

82 GS850 - 10k on the clock. I had a similar "high idle" problem when I first got it. Also it appears it had a newer head put on mine in the past.

I did this list one item at a time over the course of many weekends, with long delays waiting or parts to arrive. If I knew then what I know now, I would have bought it all at once and done it all at the same time. Just figure any rubber part that is directly attached to the engine is going to need to be replaced.

Here is what it took to get it running well:

front tire
intake boots
intake O rings
airbox boots
airbox re-seal
valve adjustment w/ realgaskets
Brake fluid flush front and rear
new petcock
Full carb cleaning (more than once)
carb vacuum gauges + colortune

Still have to do:

Fork seals + progressive springs
Brake pads
repair cosmetic damage/dents and paint tank and side covers.
 
Hey howdy hey!

Hey howdy hey!

Mr. Brent099,

Let it be known that on this day you are hereby cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Please note that "good standing" implies pictures! :-D

While you are changing the oil, don't forget to put fresh 90wt gear oil in the bevel gear case and the rear differential. For general reference you will find the carb rebuild series here and a valve adjustment pictorial here. You'll want to get a real air filter and replace all the rotted weatherstripping on the top of the filter cage and the side covers. The Uni filter uses a very light spritzing of oil.

The petcock on these bikes is vacuum operated. If you still have the original petcock and the vacuum has been defeated then you must set the petcock on "PRI" (Prime) in order for gas to get to the carbs. But realize then that the gas continues to flow after the motor is turned off leading to gas in the oil and other problems. Best get that sorted out, probably with a new petcock of the proper model.

Let us know how it goes. We look forward to helping you with your electrical charging issues too. :-D

If you'd like a Suzuki Shop Manual for your bike, PM me. I think I have an extra copy around here somewhere.

Thank you for your indulgence,

BassCliff
 
simonp said:
82 GS850 - 10k on the clock. I had a similar "high idle" problem when I first got it. Also it appears it had a newer head put on mine in the past.

I did this list one item at a time over the course of many weekends, with long delays waiting or parts to arrive. If I knew then what I know now, I would have bought it all at once and done it all at the same time. Just figure any rubber part that is directly attached to the engine is going to need to be replaced.

Here is what it took to get it running well:

front tire
intake boots
intake O rings
airbox boots
airbox re-seal
valve adjustment w/ realgaskets
Brake fluid flush front and rear
new petcock
Full carb cleaning (more than once)
carb vacuum gauges + colortune

Still have to do:

Fork seals + progressive springs
Brake pads
repair cosmetic damage/dents and paint tank and side covers.
Click to expand...

When You see the Difference in Handling You will wish You had done the Progressives Earlier.:)
 
marvinsc said:
When You see the Difference in Handling You will wish You had done the Progressives Earlier.:)
Click to expand...

I'll second that. Combined with upgraded calipers and the right pads, Ye Ha.
The other advantage is that you no longer need to check/adjust the air pressure on the front forks ever again.
 
marvinsc said:
When You see the Difference in Handling You will wish You had done the Progressives Earlier.:)
Click to expand...

Are progressive springs available for the GS550B, 1977 model and if so where are they to be obtained from.
 
GS850G High Idle

GS850G High Idle

I caused my own high idle problem by trying to sync the carbs without sealing the vacuum line to the fuel petcock. 3000rpm was the only place they'd align at all. Rode it that way for a week, got fed up and tried again, and then realized I'd just let the vacuum line dangle loose before and that put everything way out of whack. Not sure why, but my guess is that I was creating a massive intake leak on one of the carbs.

I corked the line, and started the sync process over and it came right into line. Now it just purrs at around 1000 where it belongs.
 
Suzuki_Don said:
Are progressive springs available for the GS550B, 1977 model and if so where are they to be obtained from.
Click to expand...


The Progressives dealer is in Sydney Don, give Action Suzuki a call they should be able to give you their number, or order them in for you.
 
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