St1100 too rich, stalls

[Miskusz]

Hello all!

I bought an 1997 SW type ST1100 (with Pair system) about 3 weeks ago. I really enjoyed the ride home, but everytime i stopped it's started to stall, so i had to gave throttle to it. To me this looked like that the pilots either plugged or mixture is bad.
So i took out the carbs (inside a 40 pilot) cleaned every part. The pilot jet was partially plugged.
I put it together does not wanted to start with choke only if i opened the throttle, also the plugs became black (like dusty), and after some time it stalls. So i started to play with pilot screws. Now i am at one turn out only, starts with choke, but still stalls, and plugs still black (i wiped it, put it back, run it a little - 5 min, then stalls). No popping.
I checked the pilot, if i screw it in it's closing the tunnel, also if i remove the pilot jet and spray carb cleaner inside, it's coming out at the pilot port.

I changed fuel filter, air filter, fuel pump, removed the vacum fuel cutoff.

I am hopeless, should i screw the pilot more? (Under 1?) Could be this aftermarket pilot screw behave differently then the stock one?

I attached a picture about the plug.

Thanks for everyone!

 

[Miskusz]

Hello Kaiser!

Yes i synced them, sorry for not mentioning that.
I did not checked the spark yet ( i just remove one, ground it and crank the engine?)

These are also new plugs which had this carbon over during this 2,5 week test phase.

 

[Smudgemo]

You had the carbs out and cleaned them - what does this actually mean? There are a lot of small parts in each one that need to be just right. You also should have checked the float height which could cause fueling issues. Assuming the carbs are all in good shape and fuel is good and getting to them, all you need to do is set the pilot screws to the factory recommendation, and do a sync as noted above by KS. There is a more refined process to dial in the pilot screws, but you need the Honda D tool and a good tach. Having some clarity on the carb work would help.
Also, the various hoses are probably old. Make sure they and the carb insulators that bridge the gap from carb to engine are in good shape. I followed this outline when I rebuilt two different sets and all went well. http://www.st-riders.net/index.php?topic=10249.0

 

[Smudgemo]

Oh, and check the secondary air filter mounted in front of the big filter. When it disintegrates from not being replaced, the foam bits make their way into the carbs. I'm not sure what issue it causes, but I found it happened in my first rebuild.

 

[Miskusz]

Hello Smudgemo!

Basically i followed the same from this site.
New gasket everywhere, new air-cut off, also new diaphragms (2had holes in it).
The pilot is not stock as it has no D shape (just straight cut)
Float height originally was set to 7mm, now it's on 8mm as i though maybe this is causing the issue.

 

[Smudgemo]

I don't know how sensitive float height is, but figured we should try and eliminate that, and I think an extra 1 mm would lessen the amount of fuel in the bowl. Your pilot screws might be stock. I think the Canada models used a straight cut in at least some models, so they could easily be OEM. I still think I'd focus on fuel. What sort of pump did you replace it with and why?
I just replaced one because it stopped working when low on fuel and too warm, but it was OEM and seems to work perfectly. Some have done a fix where they replace the OEM pump/pressure reg with an aftermarket that has too high of a pressure and no regulator. That could cause issues.

 

[Miskusz]

I will check with 9 mm then.
I am pretty sure it's not stock, as this is a model from Switzerland (it should have D type).
I replaced it as a precaution to an airtex e8371, but i kept the original pressure regulator in line
I also included a gauge in the fuel line, and it was around 0.1-0.3 bar tops. ( also found with that the gas cap is plugged, also replaced that too). After that it was 0.1-0.2 bar.

 

[Smudgemo]

I think I'd do a little more investigation before pulling the carbs on 1mm float height. I'm out of thoughts at the moment, but if spark is good, and air is getting in, then it's fuel.

 

[Miskusz]

Okay, thanks for all the help. I will check the sparks tomorrow and report back (little late in my country )

 

[dwalby]

I agree that plug doesn't look good, and agree with Kaiser that it could be caused by weak spark. But, since there's two coils you wouldn't expect both of them to have gone bad at the same time, the same way, but anything is possible. I'm assuming all 4 plugs look the same, you didn't specify that in the OP.

Have you experimented with raising the idle speed with the knob next to the gas cap? Not saying that will cure your problem, but might keep the bike from stalling at idle so you could at least ride it normally until you sort out the rich/weak spark condition that's blackening the plugs.

 

[Miskusz]

Hello Dwalby!

All four looks the same.
I did tried to increase it, but every time it's start to bog down, so i have to increase more and more (same as giving it throttle.)
Sadly there is no riding involved as my Beauty is still in pieces

 

[dwalby]

I was thinking more along the lines of- the black and white wire leading to the coils, giving resistance or having a short.
I don't think I ever posted a video of it but, back when mine first broke down back in January, I had exactly the same issue.
And it was after pulling the carbs too! Which made me think it was a carb problem... when in actual fact I had knocked the black and white power wire to the coils.
The bike ran to the shop.... but when ever the RPM dropped the bike would get weak and die.

Interesting, what do you mean exactly by "knocked" the black/white power wire? Did the connector become loose or partially dislodged so it was making a connection, but not a good connection?

 

[Oldbikefixr]

Hope no one interprets this criticism, just my OCD leaking out. Happens when it's raining and I'm bored.
The problem with dislodged wires, corroded connections, etc is precisely why I have abandoned the popular twist and tape method, and it's crimp/tape, pierce/tape cousins....some decades ago. I'm going to acknowledge that properly done, these connections can last for ages is done 'with purpose'...not quite sure how to word that better. 'Quick' splicing can certainly be improved with with a sealer, heat shrink tape or shrink tube, even over crimped on splices. Since I left the military, electronic repair/avionics, I have used one of two methods...solder/seal with shrink tubing or solder sleeve/heat gun. Both are much more time and environment friendly than just twist/tape.
I live in NE Texas, prior to that, Louisiana, both are alternately tolerable, hot, wet and any possible combination. My repair or add-on connections have survived 100+ degree days and cool, 99.9% humid days, sometimes just a few days apart.

 

[Miskusz]

Hello all,

I did not checked the plugs yet, will do after 10 min, when my garage will be refreshed.
So i removed all the plugs, removed the fuel cutoff and crank it. Gas is coming of from cylinder 2 and 3.
Could be that it's overflowing? Or this is normal? (Does the pistons has so much suction that's still sucking down fuel from the carbs?)

 

[Miskusz]

The breather hose is connected to the airbox (i think that's the 30mm hose). No vacuum fuel valve, number 3 cylinder's vacuum hose is plugged.

 

[Miskusz]

So there is spark, but the right side looks like a little weaker to me (not that significantly).

 

[Miskusz]

Yes, that' the crankcase breather
Yes, it's connected (and pushing a lot of air out also).

 

[mjc506]

You're getting actual, liquid fuel coming out of 2 and 3?!

Sticking floats or leaking valves?

 

[Miskusz]

Fuel vapour, yes.
I put back the plugs, run it a little, remove the plugs, remove the fuel cut relay, and now it's coming out from 1. So i pulled the carbs again, so i am open to any suggestions
Needles looks like they are closing when i blowjob air in the fuel line and close the floats by hand.

 

[Miskusz]

I will go through Adam Frymoyer's carb rebuild process, maybe i missed something...