Running Rich (?) II

[Doughty]

Hi! This is a great site. Thank you to those who host it and those who have added so much information. I've been reading through for the past few months as I have been trying to get my first XS1100 running. I've been making decent progress (although at a rediculously slow rate) and have gone from a completely dead bike to being almost road worthy. However, I'm now stuck and could use some of your collective wisdom.

First a little history: I have an '80 SG with ~20k on it. Everything appears to be stock. It sat out in the rain for a couple of years before finding its way to my garage. I've torn the carbs down and triple cleaned them. Put carb kits in, replaced needle valves and seats. Replaced the pilots (42.5) and the mains (120 on 1 & 4, 110 on 2 & 3). Set the float levels, per the manual, and then confirmed that the fuel level is ~ 3mm from the top of the bowl when the carbs are in place and the bike in on the center stand. Pilot screw O-rings were in pretty bad shape so I replaced them as well and have the screw set to 1.5 turns out from seated. Pilot screws all still have their needles and the openings into the main passage make a snug fit. Slides, and diaphrams are in good shape. Emlusion tubes are clean as are the needles but I haven't put new parts in. Needles have only one setting option. Air jets appeared to be in good shape. Found broken pickup wires and replaced them. Compression seems a little low (~120psi) but it's fairly even across all four and I'm hoping it will come up once I can get some miles on the bike. Synched the carbs at idle. Checked the carb mounts by spraying brake clean on them and didn't notice much change in idle (maybe I wouldn't get much if running rich?).

Bike starts readily and won't run without choke. Idles okay when cool (first off of choke) but won't idle at all well when warm. Really gutless at any time from idle to ~3000 - above that though, it really screams (can't wait to get it dialed in). When I bring it back from short trips, the plugs are carbon fouled.

From what I've read here, these symptoms point to the pilot circuit. However, the passages are clear, the jets are new (from Mike's XS), and tweaking the idle screw doesn't seem to improve matters much.

Anyone have any ideas???

[mro]

Hi ya Doughty

and the mains (120 on 1 & 4, 110 on 2 & 3).

Typo?, larger jets were for help to cool inside pair.
Did not see what air filter you have or condition.
Carbs (on my 80) set to 23 mm.

Did you check to see if running on all four.
As per prom(Prom), you can spray a little water on header to see if all pipes will sizzle similarly. (I've just held my hand close)
Fuel being supplied by enricher circuit. Could be one or two carbs still have a problem.

mro
btw
welcome to XSland

[Doughty]

Thanks, MRO. Yeah, the wider mains are on the inside. All 4 seem to be running - 4 hot pipes, 4 dry, sooty plugs.

Air filter is new - think it came from Parts'n'More but I've run a bit without the filter or any of the air-box parts to save time pulling the carbs off. Without, I think I was getting 21mm. Is worth re-synching with the filter on there and at a higher RPM (~2k)?

Do the pilot screws control the enrichening circuit up to the point that that circuit is no longer significant (~3k)? Should I be able to dial back the mixture with the pilot screws or would I need to get tighter pilot jets?

Although, it seems a little weird that with everything stock the pilots would be that far off. Is there any other way I could be getting extra fuel into the mix at low RPM?

[prometheus578]

Glad to see that MRO is still capitalizing my name, as is proper.
Let's see... yeah, the bigger jets go to the middle carbs.
Not knowing the bike, I tend to agree with MRO(on this occassion only)that you still have a carb issue.
The pilot screws only concern themselves with idle. A bike that only runs on choke(enrichener circuit) means pilot circuit. I know you've checked things over, but maybe a quick recheck is in order. Pull the pilot screws and ensure that they still have the tips on them and that you don't have broken tips wedged in the pilot hole.
Spraying carb cleaner in the pilot air jet at the airbox side o' the carb should spurt carb cleaner out the pilot jet tower(Where the pilot jet screws into.)
Jets, screws, needles... easy to confuse terms.
The pilot jet can be reached by taking off the float bowl. It is in a tower(Like the main jet) and is removed with a nicely edged screwdriver.
So... spraying cleaner into the pilot "Air Jet" , cleaner should bubble out the tower of the pilot jet. It' should also come out by the pilot screw hole(Where the pilot needle goes)
If all this checks out... we shall look elsewhere.

Do the pilot screws control the enrichening circuit up to the point that that circuit is no longer significant

No... enrichener circuit is it's own entity. Just works offa the choke lever system... opens a circuit and fuel/mixture from float bowl floods into the carb, through that big hole in the carb throat on the manifold side o' the carb
.

[John]

Yeah, What he said

Plus, what he didn't... look at the top of the throttle plates from the engine side of the carbs. Now look at the top of the bore of the carbs right above the plates. See the three small holes? Those are in the pilot circuit as well. That is where the fuel is drawn from when the RPM's are below 3k. One of the holes is behind the plate when the throttle is closed. As the throttle is opened, the other two holes are exposed, and more fuel is drawn into the engine. 3k RPM is the point where the diaphragms are beginning to lift the needles and more air/fuel is added to the mix, and it 'takes off like a rocket'. Spray some carb spray into the pilot jet, and leave the pilot needles in place. Check these three small holes to see if the spray is flow from them. Recheck the pilot jets to see if the hole in the tip of the jet is clear. It doesn't take much to stop one up. Like everyone is saying, the problem seems to be in the pilot circuit.

[TopCatGr58]

Hey Doughty,

Couple more questions: You said MikesXS Pilot jets, WHICH ONES? They sell 2 kind, the VM and the BS series, you should have gotten the BS series! Their metering constrictions are at the bottom nose tip, the VM has the narrowing at the thread end!

Secondly, there were some variations with the 80 carbs on some early models, where they still had the 78-79 bodies, they have the tunnel between the pilot jet tower and main jet tower. Did you see the photos in TJ's thread? If yours has the tunnel, and you DON'T have the pilot tower plugged, then the pilot circuit would be running too rich. Also, the mains would be too small?

BTW, the Pilot circuit DOES contribute to the fuel supply, albeit in a proportionally less amount as the rpms and the vacuum slides rise, they just don't stop flowing immediately once you're into the mains.

But I also concur that it sounds like your pilot circuit isn't clear, not getting enough air, or too much fuel.
T.C.

[Doughty]

Thanks for the advice so far!

Pilot screws look good - well, from my meager understanding of how they should work. They have all have comparable looking tips on them that protrude into the bore when screwed down all the way and are a bit recessed when 1.5 turns out.

I hit the pilot air get with carb cleaner and got juice out of the pilot tower. Removed the pilot screws and had carb cleaner flying out of there as well. I wasn't aware of the three holes in the bore - thanks! - found them and cleared them with a small piece of wire. I can get carb cleaner through them now.

I can't see a passage btw the pilot and main towers so I think this is the newer carb. A while back I tried the plugs I got in the carb kits but it made the thing run a lot worse.

Pilots appear to be BS type - constriction at the engine side of the circuit (away from the threads).

Had great hopes after cleaning the three holes from the pilot circuit to the bore. Took it out for a spin and it seemed like I had a little more in the low end - until it was warmed up. Seemed to rev through the lower range just fine but once under load was gutless. After lugging up a hill, and coming to a stop it wouldn't idle. Let it sit for a couple of seconds and it started right up and idled okay. Low speed running was really getting bad as I returned to the garage. Tried a little choke - just to see what would happen - and was able to crawl the last few feet. Blows my running-rich theory?

[LoserShoes]

Have you tried cleaning the tank vent in the cap? Maybe try a run with the cap off?
Sounds like it could be fuel starvation from an unvented tank. Hope it's that easy.

Steve

[mro]

Things to check

Recheck that vacuum hoses are going to the right places and any unused vacuum ports (like on the carb boots are capped and not leaking)

Left front, cover for timing mechanism. Would remove and see if still has factory "screws" that lock timing plate in place. If original "screws" in place timing should be OK. Might as well check that advance mechanism is working while the cover is off. Apply suction to it's hose, should see it move up and down as vacuum released. (btw, you do have vac advance hose attached at #2 carb body?) (also while cover is off can set cam chain tensioner)

If all above OK, then your back to fuel and spark.
(stock 11's don't run right w/o the air box and filter and sync and pilot screw adjustment should be done with em on)

Little fuel screen under float valve needle is clean? Do you have in-line fuel filters and no kinking of hoses. Know sounds dumb, but have seen hoses not routed properly and restricted fuel so that bike would start and shortly start to have problems.

So after checking above would start bike, as soon as it runs ruff would pull plug wires one at a time to see which cylinders are NOT firing. If all are firing, pretty much leaves problem with carbs, and even if one or two are not could still be carbs but can now check wiring etc.. for ones that don't to eliminate possibility of intermittent electrical problem.

Good luck

mro

[Doughty]

Recheck that vacuum hoses are going to the right places and any unused vacuum ports (like on the carb boots are capped and not leaking)

I'm thinking this steered me in the right direction. Pulled the carb boots off and found no gaskets and some dried up, crusty remnants of sealant (looked clear - never seen a high temp anything that was clear). Cleaned 'em up and put a bead of high-temp silicon on there. Put it all back together and the idle is MUCH smoother. Synch is better over range and I can set the idle down to ~900 and still have it running smooth. Also, it now returns quickly and repeatably to idle when I release the throttle.

Being a newbie I'm gonna wait for the rain to stop before taking it for a spin - and to avoid having to push it home in a downpour if things don't work out.

Thanks for the ideas everyone.

[Doughty]

After my last post, the bike continued to run poorly. Symptoms are rough running (missing) through the lower RPM range and no power, poor idle when warm (misfire, blow back), plugs quickly foul (30 sec of running) with dry, sooty carbon. As seems typical with these beasts, it takes off like a rocket above 3k.

I got a spark-checker last night and took a look at the ignition. Spark looks great - strong purple arc that will easily jump half an inch when so compelled. Spark is consistent through the RPM range and with varied vacuum (I took the advance hose off and pulled on it manually to adjust the advance). I've also replaced the plug wires. While the coils were out, I checked them for intermittent connections. Measured resistance on both sides when the coils had been in the freezer over night and also warmed up to ~150deg in the oven. Resistance varied a little with temp. (to be expected) but was in normal range consistently. Checked the shutoff switch and roll-over switch - both appeared to be in good shape and didn't exacerbate the missing when shaken or otherwise abused (although the engine did stop when the roll-over switch was rolled over - go figure). I have an oscilloscope at my disposal and was able to check that the pickup coils are given a nice consistent pulse with every revolution.

I've pulled the carb boots, painted them with Plasti-dip to seal up the cracks. None appeared to go all the way through but I thought it would help me rule them out as a problem with out dropping big $$ for new ones. Put them back on with a high-temp RTV "gasket" and they seem to seal really nicely. New caps on the vacuum ports except on 2 which is plumbed to the fuel valve. The port on the body of #2 goes to the vacuum advance which seems to be in really good shape. Sucking on it I can pull it in and when I plug the hose, the advance solenoid holds its ground until I let air in (no leaks).

Pulled the carbs off half a dozen more times and have blown carb cleaner through every circuit I'm aware of. I get juice coming out of all the places Prometheous mentioned earlier in this thread.

Float levels all look good. Resynched with the air-filter on and it dialed in pretty well.

Replaced in in-line fuel filters and some of the worse-looking pieces of fuel hose. That all seems to be routed okay - I can dump a lot of gas through when I accidentally pull the fuel line off the carbs with out shutting the fuel off first.

All three holes in the bore are clear on all the carbs, pilot screws have their pins and I have them at 1.5 turn out from seated. The little o-rings and washers have been replaced.

This thing has got me seriously confused. The idle getting worse as it warms up makes me think lean, but the plugs are saying rich, at least in my meager understanding of XS1100-ese. Gonna order up a ColorTune kit when cash-flow allows. Outside of that, I'm out of ideas on where the problem(s) could be. Any suggestions?

[TopCatGr58]

Hey Doughty,

Sorry to hear about your continued troubles! Just re-read the entire thread to catch up!

Okay, runs good a 3K +, can it get to redline?

You checked ignition coils, pickup coils, changed plug wires, but didn't say anything about checking the TIMING! The 80's have a funky break off bolt system to hold the timing plate in place, but can be drilled out and replaced with regular bolts!

You said you put in carb kits, and jets from MikesXS. Do you still have the old pilot jets? Might try swapping them back in?

80SG, but didn't mention anything about the octopus? Also, do you only have 2 sets of "T" between the carb bodies, or are there another set higher up on the body? Do you have 4 holes in your carb inlet bell, or only 3? Just checking for proper venting of the float bowls.

What spark plugs are you running? You replaced the wires, did you check the plug caps and resistance?

Sooty plugs does sound rich, either pilot jets(not necessarily screws) not right, floats too high. Good Luck!
T.C.

[AlanB]

Hi Doughty,

You say you have the pilot screws set to the "standard" 1 1/2 turns out, but these are adjusters! Try turning them further out as the bike idles; if it likes it better, the idle will speed up! keep going, 1/4 turn at a time until it starts slowing, then retrace to the best setting.

reset the idle speed using the throttle stop.

If it gets worse as soon as you turn out; try going in.

If turning the pilot adjusters does not make a marked difference, the circuit is still not working- clean it again!

AlanB

[Dennyz]

Doughty,

You did not use K&L jet kits by any chance. The idle jets in those kits are not correct and cause a similar condition.

You might pull one out and compair it with one of the old ones. If the small holes on the sides are not the same, clean up the old ones and put them back in.

[jimboreeno]

While I am not in the same league for giving advice as those before me.. . I will ask a question.
Have you been riding when the streets are dry? If not you might check the pick up coil wire. It is a real weak spot on these bikes and can lead to erratic running especially when wet. Mine acts up badly when wet and somewhat when extremely humid. (it is on my short list to fix)
It might at least be contributing to your mystery! Here is a link to the coil wire pick up fix