High Idle-

[SW]

A few weeks ago my 98  "98" standard started idling about 1400 rpms. I suspect the idle valve but don't really want to mess with it at this time of the year. Will this cause long term problems and/or is there something else I should check or do?

[shortleg]

  Have you been able to turn the
idle knob to turn down the idle?
     Shortleg[Dave]

[Mr.BubblesVRCCDS0008]

Check for a vaccum leak. all the clamps on the intake system (18) and also check hoses as they are getting old and do split easily.

[Mr Steve]

A vacuum leak would cause a lean condition and an idle drop.   Enriching causes the idle to increase.   Perhaps something is causing a rich condition (choke stuck?), but you'd smell that.  Another possibility is the timing.  An advance, like the ECT mod causes could cause it.  Perhaps the idle adjust screw just got bumped or in some way moved.  I suppose it is even possible that the throttle isn't returning all the way.

[Ricky-D]

All of the throttle linkage is subject to dryness causing some parts to not work properly.

A spray can of silicone will insure there is not a problem if you use it amply on all the linkage parts.

Take the chrome covers off for better access to all the parts.

Work the throttle while spraying.  Don't be cheap when spraying. Use the whole can if you must. You can spray everything under there, it will just drain to the surface.

Also a good thing would be to remove the two screws holding the throttle assembly on the bars and open them carefully. Squirt a few drops of oil onto the throttle cables where they enter the casings right inside there.

I would caution doing any adjustments to anything until you find the problem. Avoid compounding your problem is good advice.

***

[Bobbo]

A vacuum leak would cause a lean condition and an idle drop.   Enriching causes the idle to increase.   Perhaps something is causing a rich condition (choke stuck?), but you'd smell that.  Another possibility is the timing.  An advance, like the ECT mod causes could cause it.  Perhaps the idle adjust screw just got bumped or in some way moved.  I suppose it is even possible that the throttle isn't returning all the way.

Not true in most cases.

Most engines, especially with carburetors, run slightly rich to improve driveability and reduce detonation.  The idle mixture is a little more rich to reduce stumble off idle.  A small vacuum leak usually increases idle speed as it makes the idle mixture closer to stoichiometric.  A large vacuum leak would usually cause a lean condition and idle drop, along with a very rough idle.

Definitely check the hoses and clamps as suggested, as well as the intake runner O-rings.  Checking and lubing the linkage is always a good idea, and should be part of regular maintenance.

[Mr Steve]

A vacuum leak would cause a lean condition and an idle drop.   Enriching causes the idle to increase.   Perhaps something is causing a rich condition (choke stuck?), but you'd smell that.  Another possibility is the timing.  An advance, like the ECT mod causes could cause it.  Perhaps the idle adjust screw just got bumped or in some way moved.  I suppose it is even possible that the throttle isn't returning all the way.

Not true in most cases.

Most engines, especially with carburetors, run slightly rich to improve driveability and reduce detonation. 

Ok, I'll agree, any engines set to run  very rich already might see a little idle speed increase with a vacuum leak that causes that rich running motor to suddenly be running ideal.   I will disagree with the most comment, though, I do not find most valks to be running rich if the owner knows what they are doing.  Although, that may explain why yours runs rich enough to benefit from a vacuum leak.

[GOOSE]

sw......read what RICKY-D said above......he's right on the money (I CAN'T BELIEVE I JUST SAID THAT...WOW!!!!!!!), you will be better off taking care of the problem at hand first, instead of possibly causing more (and new) problems.  good luck....i still can't believe i said that.

[Bobbo]

A vacuum leak would cause a lean condition and an idle drop.   Enriching causes the idle to increase.   Perhaps something is causing a rich condition (choke stuck?), but you'd smell that.  Another possibility is the timing.  An advance, like the ECT mod causes could cause it.  Perhaps the idle adjust screw just got bumped or in some way moved.  I suppose it is even possible that the throttle isn't returning all the way.

Not true in most cases.

Most engines, especially with carburetors, run slightly rich to improve driveability and reduce detonation. 

Ok, I'll agree, any engines set to run  very rich already might see a little idle speed increase with a vacuum leak that causes that rich running motor to suddenly be running ideal.   I will disagree with the most comment, though, I do not find most valks to be running rich if the owner knows what they are doing.  Although, that may explain why yours runs rich enough to benefit from a vacuum leak.

Carburetor idle mixture tuning involves leaning the mixture to the point of rough idle or RPM drop, back out to smooth idle, then another 1/4 to 1/2 turn.  This is the slightly rich idle mixture I am referring to.  A small vacuum leak will cause a slight increase in idle RPM on a properly tuned carburetor.

To comply with emission regulations, our Valks have a PAIR valve system to compensate for the slightly rich idle mixture.  It allows a small amount of fresh air into the exhaust to help complete combustion of any extra hydrocarbons.

[Mr Steve]

A vacuum leak would cause a lean condition and an idle drop.   Enriching causes the idle to increase.   Perhaps something is causing a rich condition (choke stuck?), but you'd smell that.  Another possibility is the timing.  An advance, like the ECT mod causes could cause it.  Perhaps the idle adjust screw just got bumped or in some way moved.  I suppose it is even possible that the throttle isn't returning all the way.

Not true in most cases.

Most engines, especially with carburetors, run slightly rich to improve driveability and reduce detonation. 

Ok, I'll agree, any engines set to run  very rich already might see a little idle speed increase with a vacuum leak that causes that rich running motor to suddenly be running ideal.   I will disagree with the most comment, though, I do not find most valks to be running rich if the owner knows what they are doing.  Although, that may explain why yours runs rich enough to benefit from a vacuum leak.

Carburetor idle mixture tuning involves leaning the mixture to the point of rough idle or RPM drop, back out to smooth idle, then another 1/4 to 1/2 turn.  This is the slightly rich idle mixture I am referring to.  A small vacuum leak will cause a slight increase in idle RPM on a properly tuned carburetor.

To comply with emission regulations, our Valks have a PAIR valve system to compensate for the slightly rich idle mixture.  It allows a small amount of fresh air into the exhaust to help complete combustion of any extra hydrocarbons.

That pilot back off to idle rough or rpm drop is backing off until it is too lean, then enriching just enough so it is perfect.  It's not backing off till perfect then making it a little richer. 

The pair valve is only an EPA thing, it's not there to lean out a rich running bike.  As for the reclamation aspect of it as proof the bike is rich, any motor, even perfectly adjusted EFI, will have unburned hydrocarbons.  A motor isn't 100% efficient.

We're going to have to agree to disagree with this, I don't think I have ever seen a vacuum leak cause an increased idle, it's always been a lower one or a rough one in my experience.  I'm not discounting checking for vac leaks, with these bikes that's a given, just that I don't believe a vac leak on a valk will cause a 1400 rpm idle.

Guess we'll see for sure when he finds the actual cause.

[Bobbo]

A vacuum leak would cause a lean condition and an idle drop.   Enriching causes the idle to increase.   Perhaps something is causing a rich condition (choke stuck?), but you'd smell that.  Another possibility is the timing.  An advance, like the ECT mod causes could cause it.  Perhaps the idle adjust screw just got bumped or in some way moved.  I suppose it is even possible that the throttle isn't returning all the way.

Not true in most cases.

Most engines, especially with carburetors, run slightly rich to improve driveability and reduce detonation. 

Ok, I'll agree, any engines set to run  very rich already might see a little idle speed increase with a vacuum leak that causes that rich running motor to suddenly be running ideal.   I will disagree with the most comment, though, I do not find most valks to be running rich if the owner knows what they are doing.  Although, that may explain why yours runs rich enough to benefit from a vacuum leak.

Carburetor idle mixture tuning involves leaning the mixture to the point of rough idle or RPM drop, back out to smooth idle, then another 1/4 to 1/2 turn.  This is the slightly rich idle mixture I am referring to.  A small vacuum leak will cause a slight increase in idle RPM on a properly tuned carburetor.

To comply with emission regulations, our Valks have a PAIR valve system to compensate for the slightly rich idle mixture.  It allows a small amount of fresh air into the exhaust to help complete combustion of any extra hydrocarbons.

That pilot back off to idle rough or rpm drop is backing off until it is too lean, then enriching just enough so it is perfect.  It's not backing off till perfect then making it a little richer. 

The pair valve is only an EPA thing, it's not there to lean out a rich running bike.  As for the reclamation aspect of it as proof the bike is rich, any motor, even perfectly adjusted EFI, will have unburned hydrocarbons.  A motor isn't 100% efficient.

We're going to have to agree to disagree with this, I don't think I have ever seen a vacuum leak cause an increased idle, it's always been a lower one or a rough one in my experience.  I'm not discounting checking for vac leaks, with these bikes that's a given, just that I don't believe a vac leak on a valk will cause a 1400 rpm idle.

Guess we'll see for sure when he finds the actual cause.

You're correct, we'll have to disagree, since you aren't comprehending what I'm saying.

Your reply indicates you don't understand carburetor tuning, or my description of PAIR valve function.  I didn't say it leans out the mixture, I said it COMPENSATES for the slightly rich idle mixture by reducing unburned hydrocarbons to comply with emissions standards.  If you adjust the idle mixture to leanest without RPM drop, you will usually have a slight hesitation off idle, depending on the midrange mixture.

[SW]

A few weeks ago my 98  "98" standard started idling about 1400 rpms. I suspect the idle valve but don't really want to mess with it at this time of the year. Will this cause long term problems and/or is there something else I should check or do?

Thanks for all the tips. I checked all the vac hoses and found no sign of a leak so I adjusted idle down and it seems to be holding without a problem once warm. Not sure why it happened but so far so good. Thanks again. SW