Alas Another Uncle Phil ST1100 Mystery Thread

Andrew Shadow said:
OK, you had not checked the rear ones so that makes more sense now. I thought that I was missing something.
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Nope, I was missing something because I assumed ... :biggrin:
If the fronts ones were 'okay' surely the back ones would be okay. ;)
 
I don't know what kind of fuel pump you have but the factory Honda has a check valve to prevent fuel from siphoning into the carbs when shut down. If you removed the factory pump consider adding a check valve to prevent this. The Facet pump I used on my ST1100 included a check valve in it. Many pumps do not have one.
 
I would need a picture of the hose, to match up with my St to verify if it's necessary, Mine doesn't have a Pair system on it, there is a hose connecting all four CV Slides too balance them with same air pressure.
 
Uncle Phil said:
Well, Frost, one of my 97 ABSII ST1100s has decided once again to be ugly.
I've been hunting down a carb issue so I have her in my shop.
I was starting her to test to see if I had the issue resolved.
I got tired and called it quits for the evening.
When I go back out there the next morning, she will not turnover.
All I get when I hit the start button is a 'buzz' and the light bar above the speedo goes dim.
Already tried a known good battery and another known good starter but no joy.
It has already had the 'red wire' bypass done.
Battery terminals looked fine both on the starter end and the battery end.
It's almost as if the engine is locked up.
I am confused as to what could have instantly gone south overnight in a heated garage.
I guess I could pull all the plugs and see if she will turn over.
It seems I never have the 'simple' problems it is usually really weird stuff.
Any ideas?
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Try one of these! They come in “red”!
IMG_4628.jpeg
 
St-Gerard said:
I would need a picture of the hose, to match up with my St to verify if it's necessary, Mine doesn't have a Pair system on it, there is a hose connecting all four CV Slides too balance them with same air pressure.
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Is that hose connected (by junctions) to fittings in the base of the carb that are on each 'corner'?
 
St-Gerard said:
Need to clean my K&N air cleaner will take a picture of it , today.
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Curious as to where they 'end up' - I've seen some pictures where the ends just 'rest' in a bracket on the front of the carb base.
 
Uncle Phil said:
The petcock would not have stopped the bad carbs from flooding the cylinders.
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Huh? It wouldn’t…? I sure thought a functioning Auto Fuel Valve would in fact keep fuel from overfilling the float bowls, with stuck open floats, and sending fuel to the cylinder’s combustion chambers; assuming a fuel tank level above that of the carbs, AFV removed. Am I wrong….?

John (seriously trying to visualize all this….)
 
John OoSTerhuis said:
Huh? It wouldn’t…? I sure thought a functioning Auto Fuel Valve would in fact keep fuel from overfilling the float bowls, with stuck open floats, and sending fuel to the cylinder’s combustion chambers; assuming a fuel tank level above that of the carbs, AFV removed. Am I wrong….?

John (seriously trying to visualize all this….)
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Just curious as to how it could if the other carb floats were functioning properly?
 
Here's my thought: without the vacuum shut-off installed, if there is residual head pressure in the tank along with a slight vaccum from the bowls draining, it could allow fuel to be sucked in. Remember, the fuel cap only prevents air from escaping not from being pulled in as the level drops. And depending on where the crank position is, it woudn't take much fuel to completely fill the cylinder and lock it if it were near TDC.

I personally would have loved to see video of the fuel being shot out of both cylinders like a dragster as it was expelled.
 
So where to begin, stripped Tupperware and air cleaner housing, needed a bath. I believe the piping UP is looking at is the Venting for the Float bowls , plugging them not a good idea. Mine are open at the front of CarbsIMG_7687.jpgIMG_7686.jpg
 
jdmccright said:
Here's my thought: without the vacuum shut-off installed, if there is residual head pressure in the tank along with a slight vaccum from the bowls draining, it could allow fuel to be sucked in. Remember, the fuel cap only prevents air from escaping not from being pulled in as the level drops. And depending on where the crank position is, it woudn't take much fuel to completely fill the cylinder and lock it if it were near TDC.

I personally would have loved to see video of the fuel being shot out of both cylinders like a dragster as it was expelled.
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Trust me - It was pretty impressive since it shot out of both back cylinders! ;)
 
The upper tubes are bowl vents, vacuum switch on bottom left picture I don't have on my bike, so I would imagine you can cap them off at the base fittings.
 
are you browning down the battery because the starter wound rotor [whatever] is stuck? [edit] since you're voltage is apparently dropping I don't think it's relay contacts
my yamaha carb seat o-rings were leaking when I got it [which is probably why I got it] and it was only after riding the bike for a few weeks then forgetting to shut the petcock off afterward that I realized
there was a problem; pulled the twin carb assembly and the boots were filled with gas.
 
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