Starter valves sticking

[Nightmare]

Ran into a problem where the bike suddenly has an extremely high idle (4000RPM), pulled the air cleaner housing and was checking the throttle body (I assumed the throttle plates were being stuck partially open after installing the cruise control, note the bike WAS idling just fine after the cruise was installed).

I start moving the starter valves by hand and I notice that the valves for cylinders 1 & 2 don't move very smoothly and they kind of stick a bit. I suspect that what is causing my high idle is that the starter valve got stuck open and as the engine warmed up the idle kept climbing until I shut the engine off (the idle was very high upon restarting the engine).

The idle is back to normal at the moment but I am trying to fix this issue so I don't end up stranded on the road as it is extremely unsafe to ride with a 4000RPM idle (plus damaging to other components). So my question is... has anyone had luck in pulling, cleaning and lubricating these valves? What kind of lubrication would work here? Is there a way to remove the valves without removing the throttle bodies?

 

[Igofar]

Warning….do NOT clean the black coated strip on the butterflies, brake clean, carb cleaner, and many chemicals will remove this coating.
If removed, your TB will need to be replaced!
What you’re describing can be one of two things, the little pistons that can be seen through the two small snakebite looking holes, are dirty, and sticking (common).
These can be freed up with a couple drops of mmo while the bike is running.
Secondly, and probably your issue, you have fouled either the linkage rod while installing your cruise control, or the IDLE WAX VALVE LINKAGE, etc.
The idle wax valve rod is threaded DO NOT try to adjust the nut, or change the factory setting or you will cause more issues, inspect the threaded rod where it goes through the black plastic ferral, if it’s dirty, dry, or the threads are snagged on the edge of the hole, your idle will go wild until it vibrates and frees its self.
Make sure the black plastic barrel is free to rotate and move, and the threaded rod is not getting caught.
Lastly it could be air leaks from your cruise control, but I suspect it’s the rod snagged.

 

[Nightmare]

Thanks for the info! First question: What does that black coated strip do?
I'll check both linkage rods (starter valve and throttle butterfly valves), I haven't touched the wax valve linkage but that might be a good spot to check to make sure its clean as the lower portion of the throttle body assembly is pretty dirty (I was planning on pulling the assembly next winter to clean/service and then replace the coolant and vacuum hoses) plus the idle adjustment knob/rod was stuck in place and I had to free it up with some WD40 (looked like varnish on the rod caused it to seize)

And yes, I was talking about the little pistons that can be seen through the "snakebite" holes in your picture (RIP to your crack throttle body). For applying the oil, should I put a couple of drops into each hole? Should the bike be fully warmed up first? Any reason in particular to do this while the bike is running?

The cruise control is the Rostra electronic unit with no vacuum lines, since the idle returned to normal I don't suspect a vacuum leak.

 

[Nightmare]

How does the wax valve linkage work? For example, when the COOLANT is cold, is the starter valve held open and as the coolant warms the wax melts (like a coolant thermostat) which allows the starter valves to close?

 

[dduelin]

The #1 starter valve is fixed and shouldn't move at all. It's set at the factory and the other 3 are adjusted to match the vacuum of #1.

 

[Igofar]

How does the wax valve linkage work? For example, when the COOLANT is cold, is the starter valve held open and as the coolant warms the wax melts (like a coolant thermostat) which allows the starter valves to close?

 

[Andrew Shadow]

What does that black coated strip do?

It's intended function is to help prevent the build up of carbon on the throttle plates and to help prevent the throttle plates from sticking in place causing driveability issues.

 

[Nightmare]

After chatting with Igofar yesterday, I suspect the root problem is that I only half filled my radiator (I am trying to flush some dye out of the coolant in the engine after replacing the upper rad hose) and I think doing so caused air to go into the wax valve making it no longer heat up.

The starter valves are indeed sticking a bit, but once the weather warms up (currently -26C/-15F) in a few days I will test filling the rad all of the way to see if that fixes it. If not Igofar suggested checking that wax valve for paint debris from the inside of the radiator that has been known to flake off.

 

[Nightmare]

So for anyone following this/curious, the root problem was indeed my cheap ass not bothering to fully fill the radiator. Upon closer inspection there is a tube that goes from the top of the radiator to the wax valve, which promptly emptied itself so the wax valve (officially called a "SE Thermal Valve") was never able to warm up and close the starter valves.

My starter valves were indeed sticking, a bit of WD40 in the little holes worked them nice and loose in no time, plus made the exhaust smell like WD40!
The service manual specifically states to NOT use any "commercially available carburetor cleaners to the inside of the throttle bore, which is coated with molybdenum"

I wanted to fully remove the starter valves and carefully clean the bores they slide in, but that would involve removing the entire throttle body which is next year's winter project.