Idle speed
- Thread starter andypag
- Start date
Use your search for JIS screwdriver.
The idle screw is a black knob on the right side of the engine just in front of the cylinder head cover.
Crack the throttle while adjusting the knob using a JIS screwdriver (do not try and turn the black knob by hand)
Do you have an owners manual? or Factory service manual?
If not, this is the first thing you should purchase.
Welcome to the forum.
The idle screw is a black knob on the right side of the engine just in front of the cylinder head cover.
Crack the throttle while adjusting the knob using a JIS screwdriver (do not try and turn the black knob by hand)
Do you have an owners manual? or Factory service manual?
If not, this is the first thing you should purchase.
Welcome to the forum.
Andrew Shadow
Site Supporter
Warm engine idle RPM specification is 1000 +/- 100.
- Joined
- May 28, 2015
- Messages
- 328
- Location
- Bothell, WA and Surprise, AZ
- Bike
- 2012 ST1300P ABS
- STOC #
- 8912
CYYJ
Michael
Hi Andy:
Welcome to the forum. Apropos of idle speed, aim for about 1,000 RPM when the bike is warmed up, but if you can't hit that exactly, err on the high side, not the low side, this to ensure that the alternator is turning over fast enough to meet charging needs.
A JIS (Japanese Industrial Specification) screwdriver and a Phillips (cross-head) screwdriver appear to be the same, but they are not at all the same thing. There are very significant engineering differences between both the screwdrivers and the fasteners that the screwdriver fits into. All Honda motorcycles use JIS, not Phillips, screws. If you use a Phillips screwdriver on the Honda fasteners, you will chew the heads up. Have a look at this post, it will provide a full explanation: JIS Screwdrivers.
Michael
Interesting, but Ohj jeez another £20 in tools just to turn a screw!
Andrew Shadow
Site Supporter
Yes, if it is the original supplied by Honda.
Kevcules
Site Supporter
You don't have to use the screwdriver to adjust the idle, the knob is there for a reason. They do tend to get hard to turn though and using the screwdriver makes it easier to turn. Work it back and forth if it's seized and open the throttle while trying. If you're ever underneath the gas tank, and you will be , lubricate it and the cable.
These JIS screwdrivers are what you're suposed to use when working on Japanese equipment. A regular philipps head screwdriver will ruin the screws.
I been jis screwing up my fasteners all these years....
I'll have to correct you on that point
as the service manual clearly states that you are to use a proper screwdriver (JIS) and not twist the knob.Also, as you stated, the throttle should be opened slightly to take the bind off when your adjusting the cable. Forcing it in either direction without doing this may damage the adjuster.
Andrew Shadow
Site Supporter
Not disputing that the manual instructs to use a screwdriver and not to twist the knob but curiosity begs the question- what is the knob there for?
That's a very good question 
.
Its call the throttle stop control control cable.
In the maintenance section under engine idle speed it states the following:
"Turn the throttle stop screw knob as required to obtain the specified idle speed using a screwdriver."
Idle speed: 1,000 +/- 100 rpm.
It was explained to me that they put a knob on the end of the cable just to identify it, and instruct you to use a screwdriver when using it.
I betcha didn't know that you use a screwdriver to press into it to release the cable to adjust it, then pull the knob back outward to lock it in place did ya?
.Its call the throttle stop control control cable.
In the maintenance section under engine idle speed it states the following:
"Turn the throttle stop screw knob as required to obtain the specified idle speed using a screwdriver."
Idle speed: 1,000 +/- 100 rpm.
It was explained to me that they put a knob on the end of the cable just to identify it, and instruct you to use a screwdriver when using it.
I betcha didn't know that you use a screwdriver to press into it to release the cable to adjust it, then pull the knob back outward to lock it in place did ya?
No. Crack the throttle turn the screw and the knob turns with it. Various plastics can get brittle with age. I don't know that it's happened ever but it might be that trying to turn the knob could result in breaking it. That might be a reach but I've found it's just much easier to turn it with a JIS screwdriver than by the knob. More torque more control win-win.
CYYJ
Michael
Apropos of all this discussion about adjusting (turning) the cable that sets idle speed on the ST 1300 - before I did some serious disassembly on my ST 1300 (removing the complete throttle body assembly), it was impossible for me to rotate the idle adjustment cable. I thought - incorrectly, as it turned out - that the idle speed adjustment cable was a Bowden Cable, the type of cable used on our bikes between the right handgrip (throttle) and the throttle bodies.
Once I got everything apart, I discovered that the idle speed cable is a single monolithic part - the entire thing rotates. I couldn't figure out why it was difficult to turn this cable when I had the throttle bodies off the bike and on the bench with the idle cable still attached to the throttle body frame - the cable rotated with very little friction.
But... when it came time to put everything back together, installing the heat mat, installing the throttle bodies, threading the idle speed adjustment cable underneath the left frame so the knob could fit in the little holder - that's when I discovered the cause of the "darn cable won't turn" problem: Coolant hoses, vacuum hoses, real Bowden cables from the throttle handgrip, etc. are all packed in there under the throttle body assembly so tightly that the idle cable was getting squeezed (binding) between these various parts. That's why the darn thing worked fine on the bench, but would not turn when installed on the bike.
The Honda Service Manual doesn't give super-clear directions about how to route this cable. I removed and re-installed the throttle bodies (with the idle cable attached) several times before I found a path for the idle cable that minimized (but didn't totally eliminate) friction on the cable from being up against other components. Finally, I applied a liberal coating of Dupont Krytox lubricant to the outside of the idle speed cable where it fouled on other parts, and to the other parts that it fouled on. At last, I could easily adjust the idle speed cable when everything was put back together. I recommend Krytox because it is non-toxic to all the other parts around it (it is actually a food-grade lubricant) and it is stable at high temperatures.
So, some thoughts for other owners who might encounter problems rotating the idle speed cable:
1) It ain't the cable's fault. Like I wrote above, the cable is a single monolithic part, when you rotate it (either by the screw or by the knob), the entire cable rotates.
2) Although it is possible that there could be debris in the threads at the inboard end of the cable (where it screws into the throttle body frame) preventing it from rotating easily, it is far more likely that the cable is being pinched somewhere between the knob and the throttle body frame. You don't have to take the throttle bodies off to find the problem, it is sufficient to just remove the upper and lower parts of the airbox, this will let you see the path the cable takes and identify where it is binding.
3) Whatever you do, don't unscrew the cable from the throttle body frame unless you have the entire throttle body & cable assembly out on the bench. There's a spring over the end of the cable at the throttle bodies, it will come loose and fly away, and if you are lucky enough to find it, it is pure murder to try and re-install the idle speed cable onto the throttle body while the throttle body is installed on the engine.
4) Your first troubleshooting step, if the idle speed cable does not rotate easily, should be to remove the outside (right side) end of the cable from the little U-shaped bracket that it fits into, then push the cable inwards an inch or two. That just might free it up from whatever it is binding against. Once you get your idle speed set correctly, pull the cable back out and put the knob at the end of it back into the U-shaped bracket. If it still binds when in the bracket, great, be thankful - that will prevent it from turning and keep the idle speed setting where you put it.
Michael
PS: See this post for more information and some photos illustrating the problem & possible solutions.
Once I got everything apart, I discovered that the idle speed cable is a single monolithic part - the entire thing rotates. I couldn't figure out why it was difficult to turn this cable when I had the throttle bodies off the bike and on the bench with the idle cable still attached to the throttle body frame - the cable rotated with very little friction.
But... when it came time to put everything back together, installing the heat mat, installing the throttle bodies, threading the idle speed adjustment cable underneath the left frame so the knob could fit in the little holder - that's when I discovered the cause of the "darn cable won't turn" problem: Coolant hoses, vacuum hoses, real Bowden cables from the throttle handgrip, etc. are all packed in there under the throttle body assembly so tightly that the idle cable was getting squeezed (binding) between these various parts. That's why the darn thing worked fine on the bench, but would not turn when installed on the bike.
The Honda Service Manual doesn't give super-clear directions about how to route this cable. I removed and re-installed the throttle bodies (with the idle cable attached) several times before I found a path for the idle cable that minimized (but didn't totally eliminate) friction on the cable from being up against other components. Finally, I applied a liberal coating of Dupont Krytox lubricant to the outside of the idle speed cable where it fouled on other parts, and to the other parts that it fouled on. At last, I could easily adjust the idle speed cable when everything was put back together. I recommend Krytox because it is non-toxic to all the other parts around it (it is actually a food-grade lubricant) and it is stable at high temperatures.
So, some thoughts for other owners who might encounter problems rotating the idle speed cable:
1) It ain't the cable's fault. Like I wrote above, the cable is a single monolithic part, when you rotate it (either by the screw or by the knob), the entire cable rotates.
2) Although it is possible that there could be debris in the threads at the inboard end of the cable (where it screws into the throttle body frame) preventing it from rotating easily, it is far more likely that the cable is being pinched somewhere between the knob and the throttle body frame. You don't have to take the throttle bodies off to find the problem, it is sufficient to just remove the upper and lower parts of the airbox, this will let you see the path the cable takes and identify where it is binding.
3) Whatever you do, don't unscrew the cable from the throttle body frame unless you have the entire throttle body & cable assembly out on the bench. There's a spring over the end of the cable at the throttle bodies, it will come loose and fly away, and if you are lucky enough to find it, it is pure murder to try and re-install the idle speed cable onto the throttle body while the throttle body is installed on the engine.
4) Your first troubleshooting step, if the idle speed cable does not rotate easily, should be to remove the outside (right side) end of the cable from the little U-shaped bracket that it fits into, then push the cable inwards an inch or two. That just might free it up from whatever it is binding against. Once you get your idle speed set correctly, pull the cable back out and put the knob at the end of it back into the U-shaped bracket. If it still binds when in the bracket, great, be thankful - that will prevent it from turning and keep the idle speed setting where you put it.
Michael
PS: See this post for more information and some photos illustrating the problem & possible solutions.
Last edited:
Kevcules
Site Supporter
Great information Michael. I couldn't see where that cable attaches under the throttle bodies when I was in there last. I had a quick look , but it's covered very well and didn't want to have my bike apart any longer than I had to during our very short riding season.
I tried to adjust my throttle recently and used a JIS screwdriver to work it back and forth. It started squeaking loose and I was able to move it appropriately.
I was advised not to use the "knob" to adjust the throttle , but use a screwdriver on the center screw. When the fairings are off, the screw and knob are easily located, but when the fairings are back on, I don't think I can reach the knob even if I wanted to. I never noticed or knew that the knob should have an in and out position, so I'll check that when the fairings are off again.
I think I'll still try to use the "knob" if I need to when the fairings are off......don't tell Larry.
I tried to adjust my throttle recently and used a JIS screwdriver to work it back and forth. It started squeaking loose and I was able to move it appropriately.
I was advised not to use the "knob" to adjust the throttle , but use a screwdriver on the center screw. When the fairings are off, the screw and knob are easily located, but when the fairings are back on, I don't think I can reach the knob even if I wanted to. I never noticed or knew that the knob should have an in and out position, so I'll check that when the fairings are off again.
I think I'll still try to use the "knob" if I need to when the fairings are off......don't tell Larry.