Higher idle than normal when cold.

Joined
Sep 3, 2016
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1,041
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LSAC, AB & Indio, CA
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2005/06/07 ST1300
My 1300 with only 37000 kms has run flawless all its life, enjoyed great maintenance and still runs perfect. My fuel mileage is great, 51+ mpg and no codes. Recently when starting in cold weather, 1C or 32F, the cold idle reaches 3000 rpm. Prior to this, even a month ago, a cold idle would be around 2200 +/- 100 until the first bar on the temp guage, then down to 1000. Now it is 3000+ and then down to 1000. It seems the bike is screaming when that cold. New t-stat is working great. My question is this a 5 way T thing, even though it runs great all the other times or ??? Its not killing it but seems very high to run that fast with cold oil etc. Thoughts?
 
Joined
Jan 8, 2011
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7,066
Location
Arizona
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2007 Honda ST1300A
First a question for you....when you installed the t-stat, did you make sure the little rivet looking thing (vent) is at the top when installed?
The symptoms your describing sound like some vapors have settled and are clogging up the 5 way tee and / or the vacuum lines.
If you decide to go in there, replace the lines with new ones, and do a starter valve sync while your in there (your bike will like you for it).
Despite that some forum members will instruct you to alter/adjust the wax idle setting (Don't Do It). The manual clearly indicates that its set at the factory and should not be changed.
Some folks try and treat your symptoms by doing that.
Me, I would do the sync/new lines/clean tee etc.
When you install new lines, don't make them longer or try to re-route them for easier access for future services, as this will only make a longer "kitchen sink trap" in the lines for crap to gather in.
I make the new lines about 1/4 of an inch longer than stock, so the tee is sitting up a little, and when you shut down, everything in the lines goes downward and back into the TB fittings, instead of collecting in the lines or the tee.
.02
 
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cdnemsguy
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LSAC, AB & Indio, CA
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when you installed the t-stat, did you make sure the little rivet looking thing (vent) is at the top when installed
Yes indeed, up it is and working great. I just found that the idle was a lot higher recently and I would think that the t-stat was changed about 3 months ago. All has been great until cold starts on my ride to and from STOC-toberfest. I am really wondering if this is a symptom of the 5 way T although it would appear that there would be many more and consistent symptoms that appear. I have none but the high idle till the 1st bar then all is well. I agree that I do not want to touch the wax idle setting...
 
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cdnemsguy
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Sep 3, 2016
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LSAC, AB & Indio, CA
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2005/06/07 ST1300
Thanks so much guys for the info. I will check that coolant flow and see that there isn't a blockage or air lock in the line to heat the wax valve. I don't want to mess with that adjustment, but it does make sense that the heat of the coolant is not reaching the wax valve, so that is a place I will start.
 

Blrfl

Natural Rider Enhancement
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Aug 24, 2005
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5,602
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55
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Northern Virginia
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Fast Blue One
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4837
While you're under there, make sure the linkage joints are clean and free and that the linkages themselves are unobstructed.

As Larry said, don't adjust the wax engine unless you want to be under there next spring adjusting it back to where it was.

--Mark
 
Joined
Dec 25, 2017
Messages
3
Location
San Antonio, TX
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2012 Honda ST1300
I had this same issue with my bike i just got about 6 weeks ago. only had 6,025 miles on it, but had the high idle issue.
I told the dealer about my issue and described it and the solution from what i have learned here. He said unofficially YES he knew about it, but officially NO. So they won't cover it under factory warranty.
I had them clear the lines and do a flush, which was good because evidently mine had the old green coolant in it still, they put the new blue after clearing all the lines and flushing it 3 times. They pulled out a whole handful of crap calcium deposits and dirt.
No it runs like a dream! Good to know that the new coolant is good for 12,000 miles or 2 years before required service.
 
Joined
Sep 18, 2008
Messages
11
Location
Long Beach, CA
I have a 2004 with 125,000 miles, and I've just recently started to experience this high idle issue. Now living in SoCal cold weather hasn't ever been a problem, but the temperature differences have been pretty wild lately... low 60's in the morning and evening, while reaching into the 80's mid day. I'd pull the bike out of the garage, and as usual the idle starts high for the first minute and then settles down. All seems good until I'm on the highway for a few miles and the engine begins to idle high... anywhere from 2500 to 3500 RPM. This morning it was settling at 4000 RPM. Temp was in the low 60's. Fast-forward a half hour and the temp had risen to 71, and the idle seemed to settle back down to normal.

Anyway... from what I'm reading here it sounds like all I need to do is replace the thermostat, flush the radiator, and replace the vacuum lines for good measure (a good thing to do anyway after 14 years). Does that about sum it up?
 
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