Engine Idle Speed

[RzrBak]

I recently did an engine swap on my '05. Everything seems to be working well with the exception of the engine idle. Once the engine is warmed up, idle drops to around 1400-1500 RPM. I know from performing my own TBS that is should be between 1000-1100 RPM. When I turn the throttle stop screw, nothing seems to be happening no matter which direction it's turned. I've turned it counter clockwise quite a few "turns" but nothing...

Can anyone point me in the right direction as to what I can check without having to pull the throttle body 'cause I think in order to check the end of the throttle stop cable that attaches to throttle body, I'd have to remove the air filter case first...a major PITA!

 

[Ignacio]

When I turn the throttle stop screw, nothing seems to be happening no matter which direction it's turned. I've turned it counter clockwise quite a few "turns" but nothing...

To be clear, are you talking the idle adjustment knob accessible from the right side via fingertip or air screw in a throttle body via screwdriver with the tank up when you're synchronizing throttle bodies? If the latter, then look for the former instead.

 

[RossKean]

Start with a throttle body synchronization. Screw all four adjustment screws in to lightly seated. Open them all one full turn or a bit more and do the TBS from this starting point.

 

[mech 1 twa]

Also check throttle cables . Adjustment might be tight. on pull cable.

 

[RzrBak]

When I turn the throttle stop screw, nothing seems to be happening no matter which direction it's turned. I've turned it counter clockwise quite a few "turns" but nothing...

To be clear, are you talking the idle adjustment knob accessible from the right side via fingertip or air screw in a throttle body via screwdriver with the tank up when you're synchronizing throttle bodies? If the latter, then look for the former instead.

Yes, the idle adjustment knob...sorry, the service manual listed it as "throttle stop screw". Before replacing the engine, it would adjust the idle up/down when turned.

 

[RzrBak]

Start with a throttle body synchronization. Screw all four adjustment screws in to lightly seated. Open them alone full turn or a bit more and do the TBS from this starting point.

I will probably be looking at a TBS this weekend simply because I didn't get that done once everything was back together and I know the TBS was performed on prior engine that had compression issues in #3 and #4.

Also check throttle cables . Adjustment might be tight. on pull cable.

Throttle cables are tight and doesn't seem to have the 5mm play as the manual suggests. I've been told before that 8mm is a good setting. Any preference on this?

 

[RossKean]

Don't know about the Gen I but free play for throttle is recommended at 3 to 5 mm for a Gen II. You need some to prevent binding (and inability to return fully to idle especially with bars turned) but too much will make it harder to maintain smooth throttle application during startoff and shifting.

 

[mech 1 twa]

When you removed throttle body from engine did you just hang it there or disconnect cables? Free play at grip has a lot of play if return cable is loose.

REC. lift tank and check for some slack there.. on pull cable. Cable at throttle body is adjustable and also at cables from grip assy.

 

[RzrBak]

When you removed throttle body from engine did you just hang it there or disconnect cables? Free play at grip has a lot of play if return cable is loose.REC. lift tank and check for some slack there.. on pull cable. Cable at throttle body is adjustable and also at cables from grip assy.

I removed the throttle body, disconnected the cables and set it aside (on bench) so I could do a good cleaning on it before reinstalling. Sounds like I first need to recheck the cables to see if they are too tight. I didn't find the YSM very clear on adjusting cables...or maybe I just wasn't comprehending, I don't know. Any suggestions/recommendations on a post or YT video showing this?

 

[Chiefblueman]

Had this problem with my Gen1. Ross Kean has it right. After I did the TBS I couldn't get the idle speed down. Had to reset the reference point to get the adjuster back within range.

 

[lnewlf]

FWIW..I could only get the idle down by turning all 4 adjustment screws fully seated.. After I did that the idle adjustment knob worked fine down to @ 900. I found the the throttle is much less abrupt if the idle is @ 1200..

 

[BikerGeek99]

FWIW, the idle adjustment knob on my '04 wasn't working. At Tech Day a couple of years ago, I mentioned it and Intech dove in to discover that the adjustment cable wasn't attached to anything! Whatever tab that it was supposed to be attached to had broken.

He rigged up and fix and now I can adjust my idle! Yay!

 

[mech 1 twa]

Who knows at this point you have to lift tank to check cables or do throttle body SYN. Ends of cables are threaded with a nut 1 pull 1 return safety feature. They both need a little slack. If pull cable is tight it will hold the throttle bodies open. Idle adjustment cable might also be an issue not raising the idle or hung up somehow.

Cables are adjustable up at the throttle housing by pulling back rubber cover over them . Not sure if both are but Pull one is .

 

[Gitbox]

Check for any vacuum leaks around the sync nipples, fuel injectors, intake air pressure sensor and throttle body to intake boots. (Parts catalog calls them carb joints)

 

[RzrBak]

I appreciate all the input and information others have dealt with. I had plans to dive in to it last weekend but....I now have a fractured finger and it's all splinted up. Oh yeah, and ruptured the top tendon as well.

I have a hard time getting my hands in those tight spaces when nothing is broken...ain't no way I'm gonna be able to now for at least 6 weeks.

 

[Niehart]

^^^^dislike^^^^Heal well.