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Big Sigh......input needed

  • Thread starter Thread starter 520eek
  • Start date Start date
5

520eek

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?
 
You might want to look over the mixture screw make sure the tip isn't broken off? Are you getting spark to #3?
 
How far out is the mixture screw? :-k

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. :eek:

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.

.
 
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?.....
 
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
 
+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.)
 
Jacob...why didnt you just turn up the idle knob like everyone else does??? Then just readjust as the RPMs changed.
 
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?
 
chuck hahn said:
Jacob...why didnt you just turn up the idle knob like everyone else does??? Then just readjust as the RPMs changed.
Click to expand...

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.
 
520eek said:
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?
Click to expand...
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
 
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520eek said:
I do not have tool. Is there a better method than just sort of guessing and listening to it while I fiddle with settings?
Click to expand...
Let's just say that you WON'T get it by "guessing and listening".
icon_shrug.gif


.
 
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?
 
Trip???

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.
 
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.
 
If you don't have a vacuum gauge to do the vacuum synch then the only other thing you can do is a bench synch, a very good, accurate bench synch. This could be your problem, there is so little vacuum being pulled on #3 it's not firing properly?? that makes sense why playing with the mixture screw makes no difference. Pull them off and do the bench synch.
 
Where would i find the procedures for doing this bench sync? I will try looking around in the carb forum and see what I can come up with.
 
youtube

youtube

520eek said:
Where would i find the procedures for doing this bench sync? I will try looking around in the carb forum and see what I can come up with.
Click to expand...

There are a few videos on youtube showing it done. Search for mrmaxstorey. I don't recommend his method of cleaning, it's not a strip and dip. But the bench synch he does is ok.
 
Bench sync is just to get the engine running. I don't even bother with this most the time. Set the pilot screws at 2.5 to 3 turns, get the engine running, then vacuum sync. and tweak the pilot screws at the same time. Put a fan in front of the engine so you don't overheat the thing. Sometimes the engine speed doesn't change when you tweak the pilot screws and this is okay. Just make sure the total number of turns open is in the same range as the other cylinders.
 
So....I read that people leave a carb in the berryman dip for a day, then clean. I would guess I would do that as well if it had barnacles in the bowls or nastified looking stuff. The bike I got ran okay, but I decided to dip/clean them anyway so I would have a good baseline. Now I figured a brand new can of this stuff should work wonders. I dipped each carb about 20 minutes, cleaned and assembled, and installed on bike. There was the problem on #3 so I tried to swap things around a bit but to no help. Problem stayed with #3.

Off came the carbs again and I stripped and soaked #3 only and this time it was in for about 2.5 hours. Cleaned and assembled. I have read through bench sync now and apparently I had done that. I wanted to see how things worked and got it to where a sliver of light was all that was showing for my bench sync. I just wanted the bike to fire up and get running at a reasonably close setup.

So far..as you can tell by my posts. The #3 cylinder is seemingly corrupt by a failed idle circuit in carb. How long is to long for a soak in the berrymans carb cleaner? Are there o-rings on the throttle shaft that I should be concerned about if I leave carb in dip to long?

I plan to get #3 off the bike and start to soak overnight...or longer? Any other thoughts?

I do like the idea of comparing another carb to this one as I go about this cleaning process, so that will be something I can do easily and have results that will prove things one way or another.
 
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