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82 GS850GLZ will not rev out.

  • Thread starter Thread starter 79xs
  • Start date Start date
7

79xs

Guest
I'm working on a 82 GS850GLZ for a friend. He got the bike because the last owner could not get it to ever run right. It always wanted choke.. it would take 20-30 mins before you could even rev the throttle up. I keep finding problems to fix on the bike.. but none of it has any effect on the rev problem.

Problem: you can start the bike on full choke without a problem. If you try to rev it up AT ALL it will stall and spit. If you give it full choke it will rev up to around 4k. Any throttle will make it stall or stumble. The owner says the problem starts to go away if he rides it for 30-40 mins.


-Replaced the carbs. I Got a very nice set of carbs off ebay. Took the carbs all the way down. Boiled, cleaned with wire and compressed air. Put new pilot o-rings in. The bike ran 100% the same (bad).

-Replaced Intake boots and o-rings. The o-rings behind the boots were leaking. They failed a vac leak test with WD-40 and starting spray. After I replaced them I found no vac leaks.. The bike still has the SAME rev problem.

-Replaced coils with 3.0 OHM Dynateks. New wires and plugs. Ran the same.

-Checked timing with a timing light. Spot on for both 1-4 and 2-3. timing advance moves.

-Checked compression. all 4 came back good.

-Plugs are always dry when I take them out.


My next step is to check the valves. Bike has 18k on it. After that I will replace the igniter and/or advance.


Has anyone had this same problem and fixed it? I have had no choice but to keep throwing parts at it. :confused:




Thanks.
 
Welcome to the GSR


Sounds to me like a real lean condition, you stated you cleaned the carbs but did you replace ALL the O-rings in the carbs? if not go here:

http://www.cycleorings.com/

and order some.

Robert Barr is a member of this site and has sold tons of these. The price is excellent as well as the service.

While you are waiting for the o-rings, check the valves. Out of adjustement valves are a big reason a lot of these bikes end up sitting. They are probably in spec, but if you don't check you are going to keep getting asked if you have. :D

If the valves check out, take the carbs apart

While you have the carbs apart, take note of what jets are in there as they may not be stock. Also are you using the stock airbox or trying to run pod filters? I thought the 850's had a goofy air box that was prone to leaks, but I could be mistaken.

I highly doubt you have an ignition issue, and my money would be on something wrong with the carbs/valves.
 
Yes, the carbs checked out. I am making sure to fully rule things out as I replace them. The fact that an old pair of carbs do the same thing as a fully rebuilt pair makes me pretty sure the problem is not with the carbs.. It acts 100% the same way. Plus the choke should be dumping more than enough fuel into the engine to let me rev it up atleast once. I do have the air box installed and all clamps are tight. I also did a vac leak test on the airbox.

I have three other bikes with MIC CV carbs on them.. Even when they were in poor shape they allow me to rev the motor up a few times. This acts like a hard rev limit with any throttle Everytime I find a new problem on the bike I think I have it beat...

I did take a quick look at the valves.. So far I have at least 3 that won't allow me to fit a .002 feeler under them. I didn't check all of them yet.

Should I just buy a ignitor to be sure?
 
Ignitors tend to be expensive, but if you can find one cheap enough it never hurts to have a spare around if it turns out that isn't the issue.

Before doing that I'd check for voltage at the coils, adjust the valves, and double check the carb jets to make sure they are stock. The symptom you note is exactly like there is no airbox installed, but since you have it that obviously is not the issue.
 
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79xs said:
Yes, the carbs checked out. I am making sure to fully rule things out as I replace them. The fact that an old pair of carbs do the same thing as a fully rebuilt pair makes me pretty sure the problem is not with the carbs.. It acts 100% the same way. Plus the choke should be dumping more than enough fuel into the engine to let me rev it up atleast once. I do have the air box installed and all clamps are tight. I also did a vac leak test on the airbox.

I have three other bikes with MIC CV carbs on them.. Even when they were in poor shape they allow me to rev the motor up a few times. This acts like a hard rev limit with any throttle Everytime I find a new problem on the bike I think I have it beat...

I did take a quick look at the valves.. So far I have at least 3 that won't allow me to fit a .002 feeler under them. I didn't check all of them yet.

Should I just buy a ignitor to be sure?
Click to expand...

New Carbs, same as old carbs. I take it you removed all the plugs covering the Idle air fuel screw and adjusted that screw with what result?
 
Without sounding rude, this is not getting us anywhere.. I'll put it this way... this would be my 15th+ set of Mic CV carbs I have worked on. When I say rebuilt.. I mean the carbs were broken down, each body removed from the rack. Butterfly shafts were removed, each shaft seal inspected or replaced. Each carb body was boiled. please just take it that the carbs are not my problem right now. trust me.. I understand the pilots can cause all kinds of problems.. but they won't keep an engine from reving out if the choke is on. The choke dumps in way more fuel than it needs to make up for the pilots.. yes it will run like crap but it will give it enough fuel to rev up on full throttle.. the needles and mains will take over.


The fact that a fully rebuilt set carbs does the SAME, 100%, on the bike as a set that were full of rust and had bent pilot screws would tell me that the problem is downstream. or upstream in the case of the airbox I'm going to keep working the problem.. i'm just wondering if anyone else saw this same problem before.
 
Could it be a plugged exhaust? Seems like that is all that's left.
 
I'm sorry if I came across as a jackass.. I really do understand that carb problems account for 95% of bike runing problems... thats why I was so sure I could fix this bike up without a problem.. its making me work hard for it. :rolleyes:


I will have to wait until tomorrow to check all the valves. I checked a few before I left the garage.

Cyl1: In=ok Ex=Tigher than .002in

Cyl4: In:=Tighter than .002in Ex=Tigher than .002in



A plugged exhaust..... I never thought of that. It happens all the time with old trucks and snowmobiles. I will take a look in the pipes tomorrow.
 
If your plugs are dry looking, you can rule out a crook igniter.

Your symptoms are leanness.

With your knowledge on the correct rebuilding of CV carbs firmly established, there only leaves one option. Too much air getting into the cylinders and very little fuel. Recheck all the sealing areas on the airbox including the intake snorkel, and make sure that the air cleaner/filter is correctly installed.

Did anyone mention synching the carbs?:-\\\
 
I am having the same issue with the same bike and will be watching this closely as I can not find my problem either. Clean carbs, Shimmed needles, good compression, good spark. coil relay mod, harness OK (thanks again to Steve, you are THE MAN). Starts and idles fine, can give it 1/4 to 1/2 throttle, beyond that it bogs and dies. Could it be bad floats? Incorrect float height and not getting enough fuel? Hope it ends up being something simple and not costly like the igniter. Plugged exhaust, how do you check for that?
 
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You never have answered the question whether you have the stock airbox, pods or even anything on the intake of the carbs.

You can put as many different sets of carb on there as you want. If they don't have some restriction in front of them, they will ALL run like crap.



79xs said:
Without sounding rude, this is not getting us anywhere.. I'll put it this way... this would be my 15th+ set of Mic CV carbs I have worked on. ... The choke dumps in way more fuel than it needs to make up for the pilots.. yes it will run like crap but it will give it enough fuel to rev up on full throttle...
Click to expand...
If this is, indeed, your 15th+ set of Mikuni CV carbs, you should be well aware that the "choke" does not "dump" fuel into the system. The ENRICHENER system (what you are calling "choke") relies on a CLOSED throttle butterfly to have enough vacuum to pull a measured amount of fuel through the enrichener fuel tube (the skinny tube that sticks down into the edge of the float bowl cover) and the air passage that comes from under the diaphragm. Only by varying the amount that you move the ENRICHENER control lever (or knob) can you adjust your mixture to start your cold engine. If you open the throttle AT ALL, you destroy the vacuum that is necessary to activate the ENRICHENER system.

.
 
Greetings and Salutations!!

Greetings and Salutations!!

Hi Mr. 79xs,

In your "mega-welcome" you'll find a couple of maintenance lists, things that must be checked, cleaned, repaired, replaced, etc, in order to establish a baseline for further troubleshooting. You'll also find a link to a time-honored procedure for properly cleaning the CV carbs on these bikes. Keep us informed. :)

I just stopped by to welcome you to the forum in my own, special way.
big_hi.gif


If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....:)

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike! :D

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff
 
Also, I would not trust your float level settings alone. I would always use the clear tubing method to varify the actual fuel level in the bowls. You can have the floats all set the same but still have wide variations in fuel level.

Brian
 
Steve said:
You never have answered the question whether you have the stock airbox, pods or even anything on the intake of the carbs.

You can put as many different sets of carb on there as you want. If they don't have some restriction in front of them, they will ALL run like crap.


.
Click to expand...
Yes, good thought- he (79xs) said he had airbox , but no mention of filter box. Since different set of carbs and different set of coils gave same problem and yet bike would rev to 4k with choke, it would seem to be in front of carbs. Of course, why does it start to run sorta right after 40 minutes ?
 
Steve said:
You never have answered the question whether you have the stock airbox, pods or even anything on the intake of the carbs.

You can put as many different sets of carb on there as you want. If they don't have some restriction in front of them, they will ALL run like crap.




If this is, indeed, your 15th+ set of Mikuni CV carbs, you should be well aware that the "choke" does not "dump" fuel into the system. The ENRICHENER system (what you are calling "choke") relies on a CLOSED throttle butterfly to have enough vacuum to pull a measured amount of fuel through the enrichener fuel tube (the skinny tube that sticks down into the edge of the float bowl cover) and the air passage that comes from under the diaphragm. Only by varying the amount that you move the ENRICHENER control lever (or knob) can you adjust your mixture to start your cold engine. If you open the throttle AT ALL, you destroy the vacuum that is necessary to activate the ENRICHENER system.

.
Click to expand...


I understand how it works.. you are looking into it a little too deep though.. It stills pulls enough fuel to overcome what the pilot system does on the bike. thats why i'm saying that cleaning the pilot jets and air passages another 100 times won't help me until I can get the bike to rev out. I just don't care about how well it idles right now.. or how fast it responds to throttle.. I'm worried about the fact that it falls flat on its face after 4000 rpm in neutral on the center stand...no matter how i work the throttle. I also covered the back of each carb with my hand as I reved up to bike to force it to take fuel.
 
Very very odd...


I put the valve cover back on. I sat there looking at the bike drinking a PBR then I recalled another post talking about a coil relay mod.. so I thought I would double check the voltage to the coils. It showed only 9 volts at the coils and 12.10 at the battery. I did not have a headight connected when I did all my first readings last week. So I disconnected the headlight using the plug located near the right side coil. This brought the coils up to around 10.9... The bike started up and ran almost perfect ...it reved right up to 8. Very little hanging idle.. the odd part is that I reconnected the headlight and it kept running fine. I have a feeling there are some wiring gremlins hiding out.
 
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