Sins of the PO and reflections of a newb carb rebuilder of a BS32ss 1980 gs850gl

[Wingsconsin]

I haven't yet taken a shortcut that didn't end up biting me in the ass and being a pain in my back...... OH the lessons I'm learning.......

I love this attitude - LEARNING is key to development.
Once you learn all you need too - the bike will reward you with many happy miles
My GS850 has taught me many lessons over the years - all valuable -

[Uncamitzi]

In between rain storms I feel like I'm getting close. But I have a head scratcher I could use some help with. Carbs are back to stock jets, needles and have new fuel valves. The floats are at 22mm +- 1mm. Airbox is sealed with new snorkel that fits well. As per Steve I started idle mixture with the screws out 3 full turn. Using the "bip" method outlined in Basscliffs site I got the idle steady and even at 1100 rpm. Test ride #1 fouled the plugs within 2 miles of the house on city streets. Test ride two air screws dialed in 1/2 turn (2.5 out) Fouled plugs after 4 miles of city driving. Test ride #3 air screws turned in 1 full turn (1.5 out) Fouled plugs 8 miles of city driving... Test ride #4 air screws are 1/2 turn off a soft bottom. Plugs fouled after 15 miles.......

The engine runs when the screws are lightly seated (and speeds up).... According to what I've read the bike should die with the air screws dialed all the way shut....

I'm at the point of needing a hint again.

[Big T]

Ok. Clearly, running rich

Sounds like bad emulsion tubes to me

[Uncamitzi]

Ok. Clearly, running rich

Sounds like bad emulsion tubes to me

That's not good news. during the 3rd time tearing them down in a week.. ... but was not my primary focus. sigh... but that makes sense (I forgot to mention I replaced all 4 air screws too..

[Uncamitzi]

Ok... Could the stock needles I put back in be worn? If I match the length of the stock needles with the dynojet needles.... sigh... another day of tearing carbs apart... (at least I'm getting good at disassembly and reassembly) IF the emulsion tubes are worn is there a supplier anyone knows of ?

[tom203]

"The engine runs when the screws are lightly seated (and speeds up)."

these are new mixture screws? Are they mikuni? Are "chokes" closing completely when off?
make sure the original main jets that you put back in were not drilled out before the dynojet ones showed up

[Uncamitzi]

"The engine runs when the screws are lightly seated (and speeds up)."

these are new mixture screws? Are they mikuni? Are "chokes" closing completely when off?
make sure the original main jets that you put back in were not drilled out before the dynojet ones showed up

The new mixture screws are K&L. While I was cleaning the enrichment (choke) valves I did look to see if they were tight fitting (they seemed to be) I didn't really look to see if the Mukuni #115 jets were bored..but I rather doubt it he had dynajet #140's in their place ... visual inspection of the two side by side showed that the #140's were HUGE compared to the mukuni (factory mark) jets.

The first time I cleaned the carbs I found one airscrew tip broken off and jammed into the hole... I did check to see that they all were sealing when I replaced them when they were replaced. The fact that all plugs are fouling now at the same rate is at least progress... before this last re-do there was always one cylinder that was over lean and one that was more fouled than the others. #1 would be very lean and #3 would foul badly with #2 #4 looking normal.. I'm going to swap out the needles in the emulsion tubes to see what that does... because for some reason the idea that gas is flowing harder as the vacuum increases when the air screws are shut sounds to me like it's leaking past some other place.... the emulsion tubes seem to be the likely candidate to this newb.
but I will check again what you have suggested ... at this point I'm not discounting anything except that I've mistaken VM carbs for CV carbs...

[Big T]

Yes, the choke/ enrichener would be the other possible culprit for running that rich

[Uncamitzi]

I pulled the needle and measured with my trusty rusty micrometer and there is quite a difference in the diameters of the stock needles vs. the dynajet needles with the stock needles being a bit smaller in diameter than the dynajet needles. So... in with the dyna jets unless someone has a better answer..

[tom203]

Me..I'd stick with stock main and stock needle..these low trips that you are taking are likely running mostly on pilot circuit...and yours is behaving badly. Check the k&l mixture screws...do they look similar to my sketch

[Uncamitzi]

Me..I'd stick with stock main and stock needle..these low trips that you are taking are likely running mostly on pilot circuit...and yours is behaving badly. Check the k&l mixture screws...do they look similar to my sketch

[ATTACH=CONFIG]57979[/ATTACH]

IMG_20180908_143144162.jpg
The Dyna jet needles are back in. the 4 I replaced look like the 3 on the right The one on the left was a mistake that got fixed. I just went for a ride and except for a bit of an idle hang everything seems to be ok ... but I'm not done fiddlin yet.

[Uncamitzi]

Woot.... ! I think I am VERY close. Just went for a 2 hour ride up a local canyon and aside from some slight stuttering on deceleration and a couple of minor hesitations on acceleration it was a nice smooth ride.... One thing that is odd... I thought I heard a rod knock sound from the engine... when I took the stethoscope to locate the sound.... It was the gas tank... more precisely the new petcock knocking like a rod...... what the hell?

[Steve]

You were mentioning fouled plugs several times. What were the conditions for the tests? If you were just riding around the neighborhood, using all the circuits in the carbs, you still don't know which circuit is causing the problem. You need to do systematic testing. Start with fresh plugs and a warm engine. Let the engine idle for a couple minutes, stop the engine, look at the plugs. That tests the pilot screw settings. Next, find an area where you can HOLD the throttle at about 1/8 (make marks on tape applied to the throttle housing for a visual aid). Note that 1/8 throttle in lower gears will scoot you right along. Shift to a higher gear earlier, you can maintain a lower speed without accelerating. It is throttle position, not engine speed that determines which carb circuit is in use. After riding for about a minute, find someplace where you can keep the throttle at that same setting, pull the clutch, hit the kill switch and coast to a stop, where you can examine the plugs.

Repeat the "hold throttle, pull clutch, kill engine, coast to a stop" routine at 1/4, 1/2 and full-throttle settings. 20 to 30 seconds at each setting (other than full) should give you enough coloration.

.

[Uncamitzi]

You were mentioning fouled plugs several times. What were the conditions for the tests? If you were just riding around the neighborhood, using all the circuits in the carbs, you still don't know which circuit is causing the problem. You need to do systematic testing. Start with fresh plugs and a warm engine. Let the engine idle for a couple minutes, stop the engine, look at the plugs. That tests the pilot screw settings. Next, find an area where you can HOLD the throttle at about 1/8 (make marks on tape applied to the throttle housing for a visual aid). Note that 1/8 throttle in lower gears will scoot you right along. Shift to a higher gear earlier, you can maintain a lower speed without accelerating. It is throttle position, not engine speed that determines which carb circuit is in use. After riding for about a minute, find someplace where you can keep the throttle at that same setting, pull the clutch, hit the kill switch and coast to a stop, where you can examine the plugs.

Repeat the "hold throttle, pull clutch, kill engine, coast to a stop" routine at 1/4, 1/2 and full-throttle settings. 20 to 30 seconds at each setting (other than full) should give you enough coloration.

.

Thanks for that method Steve. I will get to it.. I am sure that my short test rides have mostly been on the slow circuit and that I still have some problems (most likely from this discussion something going on with the needle jets and the jet needle (emulsion tube and needle).

I was just so damn happy yesterday to be able to put 40 miles on the bike without anything getting worse or intermittent problems.

At the top of the local canyon, which is a popular motorcycle and bicycle ride, there's a little flat area where you can either turn around and go back down into the city or continue on into the mountains... I stopped after a refreshing trip up and a couple of other bikes pulled over to me.. One was a Vulcan 1700 and the other was a very nice custom chopper. They both got off their bikes and came over to look at mine... asking the history, what have I done to it and relating stories of their life on motorcycles. I told them that this was my first motorcycle and that I bought it in pretty rough shape not knowing anything about two wheeled conveyances... It was fun to have "bikers" recognize the blood sweat and tears that I've gone through to get the 850L back on top of the canyon without the decades of experience that they have had.
So, yes I will do the diagnostics you outline above.. but not today... Today I'm going for a ride....

[Tom R]

Next time you have the carbs apart, check the markings on the needles, emulsion tubes, pilot and main jets. Compare them to what’s supposed to be in there. Should be x-5 tubes and something like 5d58 needles - you’re “stock” needles being thinner than the dynajet needles sounds wrong. Square one. As noted earlier, POs have habits of drilling jets and such, so you might do good to get some new genuine Mikuni jets.... shop around and you can get them delivered to your door for about $25 for mains and pilots.
Assuming all is correct and stock Mikuni, check the fuel level in the carbs, there are several threads here on how to accomplish this... should be 5mm below the base of the carb. This is what you’re actually trying to achieve when you’re setting the float height; but those floats are old and may not be original - who knows.
Also, make sure your adjustment needles are the correct ones, there are two different types.... K&L are probably ok, I’ve heard they’re better than they used to be, but I don’t really trust them. Genuine Mikuni screws are about $12 a pop.
Make sure your “choke” is adjusted and seated, the forks should have a bit of play on the plunger slots when they’re fully seated.