RPM Stays High After Riding for a While

[TurcoLoco]

So, did you use some starting fluid and check for a vacuum leak by spraying around the boots above & below the carbs, & the VBoost manifolds to the heads? The high idle has to be happening when you spray. If the high idle goes down where you're spraying, you found one of your leaks. Keep spraying until you find them all. Maybe it's only one you have to fix. Did you check the rubber vacuum plugs on the intake manifolds, the synch ones?

Hi Fire, the boots were seated properly and I know they are super tight but I cannot say I did do the leak test as described because the high idle occurs when I am riding once I shut off the engine and restart it, it is back to normal or sometimes, after several seconds it could come down by itself too.
I wish it would do this during my troubleshooting while in the garage or nearby.
I may have to do this on a weekend and stay close to the house so I can ride back and check it as you suggested.

Vacuum plugs appeared in good shape when I took them off to do the sync on Wednesday. There was no visible cracks or holes on any of them. This is a 2006 max and was always garaged, so most of the parts are in fairly good condition.

I will update this thread once I am able to do those test. I also want to check the slides as mentioned before. These two possibilities are the only logical ones I can suspect.

Thanks!

 

[dannymax]

Turco, you can test for vacuum leaks anytime, I use propane (unlit) but ether, starting fluid and I guess WD-40 and carb cleaner work too.

Spray whatever you use all around the carbs & boots, you're looking for a change in idle.

Your issue sounds like a vac leak.

 

[TurcoLoco]

Hmmm, during my lunch break, I grabbed a phillips screw drivers and unscrewed the two phillips screws holding the control unit next to throttle to see is the throttle and return cables were somehow binding or not. Return cable or whatever it is called seemed a bit dragging but overall it looked operational so I said "screw it" and screw the unit back on but not too tight.

On the way home, there was no high RPM scenario! :ummm:
When I got home, I still checked for a leak using a compressed air can around the boots below and above the carbs....not a single change in idling!

Was it the problem and somehow disassembling and re-assembling it resolve the issue or may be it had not reared his ugly head back out just yet?

Not sure but I think I will have a drink or two tonight and cross my fingers when I test ride it tomorrow.

Hopefully I didn't just jinxed myself!

Stay tuned...

 

[TurcoLoco]

Danny, I finally nailed the cause (totally my fault): The idle screw was moving up by itself due to the missing spring that goes on the idle screw! :bang head:
So, when I have the throttle open for more than a few seconds, the idle screw was gradually but surely, moving up!

I figured this when I took the bike on a long ride on the freeway and after riding 15-20 minutes at around 80mph, I realized I couldn't cut the gas! It was a bit scary to roll off the throttle quickly to slow down due to traffic/cars, etc. and only to realize Max keeps going like the energizer bunny all on its own! It was like a hidden cruise control. Scary I tell ya!

When I pulled over in a jiffy, Max was yelling at about 4.5K RPM. I quickly hopped off the bike and noticed the idle screw was about 1/2 higher than I positioned it when it was nicely idling at 1K RPM. I turned it c-clockwise and it came down instantly! :eusa_dance:

I recalled seeing a spring on the idle screw but I guess when I took the screw off to straighten out the bracket and clean it up, the spring must have fallen off. I remembered finding a 1 inch spring on the floor when doing the oil change and wondered where it came from. It was a total "Oohhh!" (light bulb came on) moment.

Well, now that it's fixed and running well (for now at least), I can start on the Super Magna.

Thanks everyone! :clapping: :worthy:

 

[Fire-medic]

Wow, good for you! I never throw-away anything I find on the floor until I am sure it's nothing of use. I have a separate bucket to hold stuff like that until I figure out what it is or where it came from.

 

[TurcoLoco]

Wow, good for you! I never throw-away anything I find on the floor until I am sure it's nothing of use. I have a separate bucket to hold stuff like that until I figure out what it is or where it came from.

No kidding, huh? My dad was like that and as I get older, I realize I am becoming more like him!

I would have never thought that the idle screw could roll on up all by itself in a matter of a few minutes like that. Thank god I remembered seeing the spring on it before and when I pulled over to check it, it caught my eye and got me thinking which eventually led to the Darwin moment!

I am glad I was able to figure it out before something bad happened!

Cheers everyone who chimed in!
unk:

 

[dannymax]

No kidding, huh? My dad was like that and as I get older, I realize I am becoming more like him!

I would have never thought that the idle screw could roll on up all by itself in a matter of a few minutes like that. Thank god I remembered seeing the spring on it before and when I pulled over to check it, it caught my eye and got me thinking which eventually led to the Darwin moment!

I am glad I was able to figure it out before something bad happened!

Cheers everyone who chimed in!
unk:

I would never have dreamed that idle screw would 'walk up' on it's own either....this is a brand new one Turco....just when you think you've seen everything!!

Man, that must have been a bad moment on the freeway, sure glad you found it before disaster struck! :clapping:

 

[Fire-medic]

Two words-"kill button."

I would never have dreamed that idle screw would 'walk up' on it's own either....this is a brand new one Turco....just when you think you've seen everything!!

Man, that must have been a bad moment on the freeway, sure glad you found it before disaster struck! :clapping: