Re: Cold idle at 4,000 rpm's! Problem Solved!
My 2005 ST1300 began a warm-up high idle problem last winter. This means that it would the warm-up high idle would run up to 4,500 rpm's for about 4 to 5 minutes. This is way too much, for way too long! It should have a warm-up high idle of about 2,000 to 2,500 rpm's, for no more than about 1 minute to 1/2 minutes (depending on how cold the ambient temperature is).
I also found, that even after it finally idled down to the normal 1,000 +/- 100 rpm's, I still had a problem. If the ambient air temperature was below about 45F, when I would come to a stop and pull in the clutch, the idle was high again (4,000+ rpm's).
Since I don't trust the STealers, I've been working on the problem for about 1 year now.
This is how the warm-up is supposed to happen:
1. When the ambient temperature falls below whatever solidifies wax, the wax inside the SE Thermal Wax Starter Valve (SETWSV)will solidify and contract.
2. The contraction of the wax will pull in the valve plunger and shaft. As a result, this will open ports on each of the throttle bodies via linkages.
3. When you start the engine, the butterfly vavles in the throttle bodies are closed, so now the opened ports allow air to enter the throttle bodies and mix with the fuel. Without this, the engine would be "choked" and wouldn't start.
4. Once the engine is started, coolant begins to flow through the hoses connected to the base of the SETWSV. As the engine begins to warm-up, the butterfly valves begin to open, and the wax in the SETWSV begins to melt and expand.
5 As the wax expands in the SETWSV, it pushes the valve plunger and shaft outward and starts closing the throttle body ports. (If the wax doesn't expand, the ports will not close and the increased volume of air from the opening butterfly valves and the open ports increases the rpm's excessively.)
THE PROBLEM SOLVING BEGINS:
I started by adjusting the nut on the end of the SE Thermal Wax Starter valve. This reduced the rpm's at warm-up, but then I couldn't achieve the necessary high (2,000 to 2,500 rpm's), dropping to the normal 1,000 +/- 100 rpm's. I adjusted the nut back to it's original position.
I then tested to see if the SETWSV was actually functioning. I applied heat directly to the SETWSV with a heat gun. The valve plunger pushed out. I applied cold with a lot of ice directly to the SETWSV. The valve plunger pulled in. Conclusion: The SETWSV was functioning correctly!
I knew that when the ambient temperature was cold the valve plunger was pulled in, but as the engine warmed up, the plunger didn't not readily push out. So, this meant that there must not be any warm coolant running through the hoses connected to the SETWSV. The wax was only melting as a result of heat rising off of the engine, and as I rode a few miles in the cold, the SETWSV was no longer being exposed to the engine heat. It was exposed to the cold ambient air - causing it to contract and pull in the valve plunger.
Since the warm water for the SETWSV comes from the warm/hot water outlet fittings on the top of the engine, just underneath the throttle bodies, there must be a clog or a kink in the hose. I dreaded disconnecting the throttle bodies and lifting them out. SO I DIDN'T!
When you look at the attached image, called the SYSTEM FLOW PATTERN, you will see that SETWSV hose outputs to a "T" fitting, and then to a fitting on the right side of the radiator, just under the radiator cap.
Before starting the engine, I removed the right-side fairing. Then I removed the radiator cap. I started the engine. You should see flow inside the radiator neck at the fitting mentioned above. Next, I clamped the hose (as shown in the attachment), to isolate the flow from the engine, so that only the flow from the SETWSV would be visible. Guess what? - NO FLOW! Aha! My suspicion is correct! Now what do I do?
Here's what I did:
1. I turned of the engine.
2. I disconnected the hose at the radiator fitting, and connected a brake bleeder suction device to the hose. No matter how much suction I applied, I couldn't get any coolant into the hose. NOW WHAT?!
3. I turned and saw my air compressor, and a crazy thought entered my mind. If I can't suck it out the clog or kink, maybe I can blow it out! I started my compressor and waited until it reach 160 lbs. I put the blower fitting of my compressor into the hose and squeezed the trigger ... what a mess! Coolant shot out of my open radiator - all over me, the bike, and the ceiling of my garage! What and idiot!
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4. I reconnected the hose back onto the radiator fitting. With the other hose still clamped. I said a little prayer and started the engine. SUCCESS! I now have flow through the coolant line for the SETWSV!
I let it run for about 20 seconds to purge any air, and shut off the engine.
5. I cleaned my glasses, mopped the bike and the garage floor. Then I removed the clamp from the other coolant line, and reinstalled the radiator cap.
6. I drove to the Honda (car) dealer and bought the pre-mixed blue honda coolant, and refilled the radiator. That's what I have used since I replaced the thermostat about six months ago.
7. With the engine still cold, I started it up. It high idled at about 2,100 rpm's for about 1 to 1/2 minutes and then eventually dropped down to about 1,000 rpm's.
8. I thoroughly cleaned the bike and took it out on the interstate for a 40 mile round trip test. The ambient temperature was 37F. I tried pulling in the clutch several times. It maintained the normal 1,000 rpm low idle!
Unfortunately, I don't know if there was a clog or a kink. I don't know if it will come back. But for now, I'm one happy ST1300 owner!
Dale