When starting my 1300 on cool mornings the idle begins at 1500 rpm, and gradually goes up to about 3750 rpm. It will stay there for a minute or so and the gradually go back down to a normal idle of 8 or 900 rpm. Is this normal? I think 2000 rpm would be more in line of what should be. Any suggestions?
Excessive Idle on cold start up
- Thread starter Gloryoski
- Start date
My 2007 ST1300 did the same for the 5 years I owned it. I got used to it, but it was a bit annoying when temps got below 35 degF. My solution was to ride it right away and use driving as warm up rather than high idle. From what I have read this may be related to the wax valves - and I think you can actually adjust how high you idle cold, but someone else can likely help way better than I
- Joined
- Nov 4, 2018
- Messages
- 830
- Age
- 79
- Bike
- GL1800, ST1300
My '07 had the FI code 25 faults when I bought it. The PO was nice enough, to be honest with me about it and I got a very reduced price for the bike. I checked the knock sensor wiring and found the fault to be in the ECM, I replaced it with a used one from a '03 bike. Since then the high idle is no more. Living in Florida, I don't get many cold mornings, but the original ECM had a fast idle of about 1500 RPM for a minute or so and the replacement does not change the idle at all when the engine is cold.
My ST does the same thing most of the time from cold although not as high as 3750, its actually a but erratic and went though a patch of not increasing the rpm at all and instead stumbling till it warmed up, now its back to stumbling for a few seconds before higher revs ... most of the time. Over the winter I'm going to clean out the 5 way T, replace the vacuum tubes and sync the throttle bodies, none of these have been touched since new, I'll report back in 2020 on the results!
CYYJ
Michael
While you are in there (meaning, whilst you have the lower half of the airbox off to let you do the above-mentioned work), take a very close look at the underside of the throttle bodies, especially at the arm that runs fore and aft under the left side (the wax valve attaches to this arm). You might discover that something is fouling either that arm or the wax valve, and this might account for the very fast idle during warm-up.
I removed the throttle bodies from my 1300 last winter. I didn't have a problem with fast idle before I removed them, but I did have a problem with a very fast warm-up idle after I put everything back together. I discovered that there was interference with the arm that the wax valve attaches to. I got rid of that interference, and that solved the problem.
Michael
- Joined
- Jun 21, 2011
- Messages
- 893
- Age
- 72
- Location
- Ada ( Grand Rapids ) Michigan
- Bike
- '07 ST 1300 & '91 GW
Wow , I actually learned something today !
CYYJ
Michael
Here are two pictures that illustrate where the wax assembly is, and how crowded by other components it is.
The second picture is a zoomed-in portion of the first picture.
Michael
Wax Assembly controlling idle speed after a cold start
The second picture is a zoomed-in portion of the first picture.
Michael
Wax Assembly controlling idle speed after a cold start
The service manual clearly states that the nut you adjusted should not be altered.
Don't be surprised when you find out that you just created another problem somewhere else.
The high idle is normally caused by crap in the coolant line from the 3 way tee rearward. Search the forum.
You can remove the 3 way tee and GENTLY blow air into the system to clear it out, or use a bulb or syringe and inject and pull out all kinds of crap, fixing your high idle the correct way.
when the weather changes you'll figure out why you should not have adjusted that nut
What you say is true. I did try flushing the coolant and still was an issue for me. I agree its not the correct way to fix it. But I picked the bike up cheap for 3k and was willing to risk it. I have been using it as daily commuter for the past 6 months in 100 degree temps and 30s in the mornings and haven't noticed any hiccups in performance or hard starts as of yet.
Attachments
When you say you flushed the coolant, did you remove the hoses off the radiator and clean out the black paint that is on the inside of the spouts? This is usually what clogs stuff up.
Did you also replace the t-stat, O-ring, and front water pump cover?
Find the hose that comes back from the radiator cap to the three way tee just in front of the right cylinder head, then the pipe that points sideways is the one you'll want to pull off and clean that circut out. Be very careful with the plastic tee fitting and don't over tighten the clamps or it will crack. I suggest to use a syringe instead of air to avoid blowing coolant all over the garage
Did you also replace the t-stat, O-ring, and front water pump cover?
Find the hose that comes back from the radiator cap to the three way tee just in front of the right cylinder head, then the pipe that points sideways is the one you'll want to pull off and clean that circut out. Be very careful with the plastic tee fitting and don't over tighten the clamps or it will crack. I suggest to use a syringe instead of air to avoid blowing coolant all over the garage
I will concede I didnt go that far when I flushed all fluids when I purchased the bike and the coolant looked fairly clean. In the next few weeks I plan on having the bike painted, once I have it torn down I will attempt the steps you have shared above, as I did notate how many turns I adjusted the nut and can set it back to factory. Everything on the bike seems to function as it should, you seem like an expert on this bike so I do notice some slight grind shifting from 1st to 2nd when above 4000rpms. Are the sincronizers hard to get at, does the motor need to be pulled. I plan on buying a repair manual but haven't gotten around to it. Thanks for your input.
You can see the starter valve adjusters in the photo, these are the 4 black plastic stubs on the inner side of the throttle body pairs. Three of these have adjusters and the 4th is the fixed reference. Somewhere in the middle of the TB you'll find the 5-way joint where the four hoses connect, these are the ones to connect to the vacuum gauges for the synch. The manual also says to remove the PAIR hoses and cap these off at the camcover, I confess I can't follow the logic in that so I just plug the inlet hose for the PAIRs (at the rear of the TB next to the fuel pressure reg in the picture).
Thanks for the return input. Going on a ride tomorrow, should be around 30 degrees at departure time. I'll find out then how long it takes for idle to normalize in cold weather from 3500 rpm. I bought my bike 3 weeks ago with 175 miles on it. It now has about 750 miles on it. Being essentially a new bike do you think the trash/sludge is likely to be a problem?
175 miles? Or 200,175??
CYYJ
Michael
Here's a photo that shows the small nuts that are adjusted to synchronise the starter valves. This picture shows the right-hand side of the throttle body, which is cylinders 2 and 4. Cylinder number 1, which is the forward cylinder on the left side of the motorcycle, does not have an adjustment. You synchronize cylinders 2, 3, and 4 to match cylinder 1.
You mentioned that you intend to buy a service manual - that's an excellent idea. I recommend the Honda publication, which is their publication number 61MCS11. The instructions for carrying out the starter valve synchronization can be found on pages 5-134 to 5-136 inclusive.
Michael
Starter Valve Adjustments
(disregard the forceps, this picture was taken to illustrate how to measure correct tightness of the boots below the throttle bodies)
175 miles. About the distance from Nashville to Memphis.