Big Sigh......input needed

[Guest]

So I got this 1980 850g. Went through and took care of all the top 10 known issues. And I still can't get #3 carb to respond cleanly as the others when I fiddle with air /mixture screw. I went ahead and got new coils,wires, plugs and did coil relay mod....sigh...no help. I even re soaked that carb for a good two hours and re cleaned...still no go. When I put new coils in I took apart electrical connection under frame and cleaned, re made and even tightened the single bullet connectors. Upgraded grounds, and even put new carb diaphragms in. After all of these items...I can not get #3 to respond to mixture screw....now I am doing this by ear. I can definitely hear a difference on the other cylinders when I adjust mixture screw. I even checked compression...about 115 on all cylinders. Seems to run pretty good when on the road. Am I missing something? I have read that #3 is the master carb and does that have anything to do with it? I have fiddled and adjusted the carbs so it idles at 1000-950 and it has real nice rev when you blip throttle. Am I being to picky and should just button it up and take it for ride?

[Sci85]

Am I being to picky and should just button it up and take it for ride?

I think you answered your own question.

[Master077]

You might want to look over the mixture screw make sure the tip isn't broken off? Are you getting spark to #3?

[Steve]

How far out is the mixture screw?

Don't be afraid to go out farther with it.

When I got done with the carbs on my son's 650L, I could not get it run on all four cylinders. I had all four mixture screws set to my normal three turns out to get the bike running, but it sounded like it was only running on three cylinders. Feeling the exhaust pipes, I determined the culprit was #3. I took the carbs apart and checked all the pilot passages, they all seemed good. A friend came over and played a bit with the carbs while it was running 'not so well'. All of a sudden it started PURRING. I asked him what he did, he said he just turned the mixture screw on #3 out a bit more. Turns out (pardon the pun) that all the others only required about 2 1/4 to 2 1/2 turns out, but #3 required just over 4 turns.

I really need to go into the carbs again just to verify that the pilot jet is the same size as the others, but it's running so well, we hate to do it.

.

[520eek]

Okay....to be perfectly honest....I am going to attach a sidecar to this bike tomorrow...after putting in polaris R/R.

Then I have to wait until next weekend to put new petcock on tank before I can even think about riding it. So the the following Thursday ( the 13th ) take off on a 1200 mile trip and feel good about all the work I have done to make sure I won't be at the mercy of a stupid failure.

And since I have bought the bike " unseen in person" and have been fixing it up since.....I have managed to put only 7 or 8 miles on it.....

What could possibly go wrong?.....

[londonboards]

Unless I missed it - I don't see that you mentioned carb synching. The symptoms may be a result of carb no. 3 being out of synch with the others or more correctly the other 3 being out of synch with carb no. 3.

I was surprised at just how many things fell into place after a good synching.

Greetings

[jabcb]

+1 on the carb sync.

Helped my mechanic/friend with the sync on my GS550L. Definitely pleased with the results.
(My job was to hold the throttle to keep the rpm where he wanted.)

[chuck hahn]

Jacob...why didnt you just turn up the idle knob like everyone else does??? Then just readjust as the RPMs changed.

[520eek]

I have not done a carb sync.... I do not have tool. Is there a better method than just sort of guessing and listening to it while I fiddle with settings?

[jabcb]

Jacob...why didnt you just turn up the idle knob like everyone else does??? Then just readjust as the RPMs changed.

lol. (An old geezer using that expression again.)
Maybe so I could be important too.

My job was to push the starter button when my mechanic/friend used a timing light to set the timing.

[Gorminrider]

So I got this 1980 850g. Went through and took care of all the top 10 known issues. And I still can't get #3 carb to respond cleanly as the others when I fiddle with air /mixture screw. I went ahead and got new coils,wires, plugs and did coil relay mod....sigh...no help. I even re soaked that carb for a good two hours and re cleaned...still no go. When I put new coils in I took apart electrical connection under frame and cleaned, re made and even tightened the single bullet connectors. Upgraded grounds, and even put new carb diaphragms in. After all of these items...I can not get #3 to respond to mixture screw....now I am doing this by ear. I can definitely hear a difference on the other cylinders when I adjust mixture screw. I even checked compression...about 115 on all cylinders. Seems to run pretty good when on the road. Am I missing something? I have read that #3 is the master carb and does that have anything to do with it? I have fiddled and adjusted the carbs so it idles at 1000-950 and it has real nice rev when you blip throttle. Am I being to picky and should just button it up and take it for ride?

I think the "mixture screw" is more about idling...ie: low revs. It has less effect on running as you open the throttle.
Therefore, as master007 said...and check all the springs,washers, and o-rings are there per a parts diagram.An o-ring might as well be replaced if there's any doubt. You can also swap the needle carb to carb if there's any doubt. I'm not going to look your bike up but some carbs have rubber plugs on the "well" and these can fail too.
The next thing is to verify the idle-mixture passage is clear and functioning. Look for a good diagram of your carb and trace that passage/circuit.I don't trust a mere soaking to ensure this. if I can't blow thru it,I will try to to pump fluid thru this passage .
Comparing the flow/and blow with a working carb's idle circuit can inform you.

If not, and you are SURE that it's blocked-corroded, (ONLY if) welding tip cleaners and bits of wire...
Every part of these passages is straight and you can't push a piece of wire through the whole thing,round the bends, but you can almost always get it clear WITHOUT removing the factory plugs where they actually drilled these...

this naturally assumes that everything else is ok that might affect idling. The rubber intake manifolds for instance...the bowl gasket...yadayada

[Steve]

I do not have tool. Is there a better method than just sort of guessing and listening to it while I fiddle with settings?

Let's just say that you WON'T get it by "guessing and listening".

.

[520eek]

I am sure I won't get it by fiddling and listening...but hope to get close. I did run it after new R/R was installed via axillary shop made tank. I start it up and can tell that it's just not firing on one of cylinders, I can run my hand over the header pipes at this point and tell it's #3. I can even wrap my hand around this header pipe for a good 30 seconds...by now all the other pipes are very hot..( I now have a nice double burn on my palm to prove it..OUCH ) If I yank a plug off of a different cylinder at idle there is a noticeable difference..however none is noticed when I pull #3. Also at 2500 rpm I can pull wire #3 and detect some sort of drop...but not as dramatic as the other carbs.

I do have new intake boots along with o-rings. The new coils/wires give A WAY BETTER spark than what was on bike. So that upgrade was decent enough!

I have soaked the carbs once and refurbished them. Re-soaked #3 again and I have compressed air to help . All for naught. When I squirt cleaner through the passages, I can see what appears to be an good amount of fluid coming out of the end of said passage.

I guess , perhaps, one more soak? Dunno....If I rev it up and hold it at 3K the header starts to warm up okay.

I am still thinking its something on the idle circuit and just button it up and go for my trip and deal with things when I get back. Surely I won't be calling my friend with his trailer to come get me over an idle problem?? Yes/No?

[habsdoc]

Trip???

You are going on a trip with a bike that is not firing on all 4 cylinders properly??? I think I would swap around or change the sparkplugs. I would also try to switch the plug wires from one side to the other and see if the problem moves. You could just have bad plug, cap, or a weak spark on #3 wire.

[520eek]

I have new coils/wires/plugs...super good spark! I forgot to mention also ( i was holding ice cubes in a rag to lessen the burn in my hand...doh ) That I had taken the screw all the way in and all the way out till it was in my hand and did not perceive the slightest difference last night. I will do wire swap again though. I did that many tries earlier and problem stayed with #3.

I think it is firing at speeds though....the little that I have rode it...sure runs nice and smooth. I am going to pull carbs one more time and try and figure it out. Maybe tonight after work I will yank those suckers out.