Bizarre, funky issue when rolling up to a stoplight

[Catbus]

Well I went and took the bike for a warm-up. Followed advice and kept the choke active for as long as it would let me.... until I got halfway up the hill and it bogged and stalled lol I did not touch my idle screw until I rode around for a couple KM and then stopped, it still does the idle hanging, but this time only to about 2K. After riding it around for about an hour and I was riding it hard, the issue can still be replicated every time. I can force it back down by letting the clutch out to the biting point, but that doesn't solve the problem does it? Once I burn though this tank (still half full and I filled it a while ago, darn bike MPGs!), I will rip off the petcock and take it all apart, brush everything with gas, and soak it overnight. With the tank off I'll wiggle every carb tube and boot seal and check everything is sealed nice.

If none of that help, I suppose it's time to dis-assemble the carbs and pray I don't lose anything lol
oh, and buy all the little tools for dealing with the jets.... yiiippeeee

[Big T]

If your petcock is not working, is there a hose between the petcock and the #3 carb?

[Catbus]

Agreed with Steve here. Anyone owning a 38 year old bike MUST either work on their own or have a ton of $$$ to throw at a mechanic. Finding one to work on these bikes is a whole nother matter. Learning to work on these guys is half the fun.

If your petcock is not working, is there a hose between the petcock and the #3 carb?

I just checked and yes, there is a hose hooked up to the petcock and to a carb, not sure which side starts as 1. there's 2 vacuum hoses [edit: a fuel overflow and a vacuum hose] too for what its worth, too. I made sure to move them to a spot where no pockets of wind or anything can disturb this sensitive black magic.

[Catbus]

holy crap have I had the actual vacuum hose and the vacuum hose for operating the petcock diaphram switched the whole time? If carb #3 is the one with the idle screw.... that one is a freehanging "vacuum hose"

i'm going to look at more youtube videos....

[steve murdoch]

Not sure which carbs you have but hose locations can be found here.

http://members.dslextreme.com/users/storagecliff/images/hose_locations.html

[Big T]

Carbs are 1-4 from left to right as you sit on the bike

#3 has a port on the left side, that's the vacuum port.

The other "ports" are vents. They're between 1-2 and 3-4

[Big T]

Not sure which carbs you have but hose locations can be found here.
http://members.dslextreme.com/users/...locations.html

wrong carbs, that diagram does not apply

[Catbus]

Carbs are 1-4 from left to right as you sit on the bike

#3 has a port on the left side, that's the vacuum port.

The other "ports" are vents. They're between 1-2 and 3-4

Thanks,

they're Mikuni VM22SS I believe.

[Catbus]

Carbs are 1-4 from left to right as you sit on the bike

#3 has a port on the left side, that's the vacuum port.

The other "ports" are vents. They're between 1-2 and 3-4

So if #3 is the one that goes into the petcock, and #2 is a vent hose... I've had the vent hose hooked up to the Petcock this whole time since I adjusted the floats in the carbs several weeks ago... and I guess thats why it doesn't pull a vacuum to work on the other modes than PRI.
Counter-intuitive since the #2 vent hose is closer to the petcock, and the actual vacuum hose goes across the leftside 2 carbs.

[Big T]

I believe they needed the space between 2-3 to get the vacuum port in there. Next time you have the carbs off, look into the intake side of #3 and you'll see the hole that creates the vacuum

Hooking up the hoses correctly may solve your problem

[Catbus]

Okay I went and took a picture of my setup, the top hose closest to the petcock is the one attached. I started the bike and felt no suction coming from the far right hose pictured. Carbs numbered left from right.




dual.jpg

[OldVet66]

That dangling hose is a vent line originally over the air box from carburetor 4. There is a corresponding vent line from carburetor 2. The vacuum port is blocked from view by your fuel line from the petcock and the fin on the back of carburetor 3 in the picture of 3 and 4. It comes off carburetor number 3 in a similar position as the vents on 2 and 4. Is that just the picture angle or is the fuel line damaged where it curves into the fuel T?

[Catbus]

Okay so I took another photo, if the vacuum hose is on the same carb as the one with the fuel line, than I do have vent hose on Carb 2 hooked into my petcock. Carb 4 has a dangling hose, carb 3 has a dangling hose. The fuel line is not kinked but is slightly wet where it enters the petcock so I will replace it most likely.
As seen in the 2nd part of this photo,
20626195_10155159910897415_1795787851153142577_o.jpg

That dangling hose is a vent line originally over the air box from carburetor 4. There is a corresponding vent line from carburetor 2. The vacuum port is blocked from view by your fuel line from the petcock and the fin on the back of carburetor 3 in the picture of 3 and 4. It comes off carburetor number 3 in a similar position as the vents on 2 and 4. Is that just the picture angle or is the fuel line damaged where it curves into the fuel T?

[OldVet66]

It appears that you have the vacuum line in your hand in the first photo looking at carburetor 3. Put that on the petcock vacuum line. Get rid of that junk setup with the fuel filter. It's just restricting fuel flow. Your petcock has a more than adequate filter screen in the fuel tank. That line should go directly from petcock to fuel T. That may solve your problems in that respect, but proper jetting may be your next concern.

[Big T]

Ok
You have the vent hose connected to the petcock
Connect the hose from #3 to the petcock and see what happens