RPM's wander at 3k

[kodiakfisher]

Ok so carbs are synced have stabil in the fuel go out just to keep the fuel from sitting too long in the carbs.

Bike starts up great, idles fine, revs silky smooth, no doubt I could pass the nickel test. If I hold the the throttle steady around 3k RPM the RPMs wander up and down about 100 RPM's and I can hear it a bit in the motor. So I back off to 2k RPMs thinking I would be checking two different circuits in the Carbs same thing. I have put all new spark plugs in the bike but want to get the consensus from the group. I have checked the intake boots and they are all tight.

There is zero chance I am tearing apart these carbs over such a relatively small issue as my dads and mine get within 1mpg of each other. I do wonder if I know my pipes are getting condensation in them while sitting out in the garage could I be getting a bit of condensation and moisture in the tank. I am in a 10% ethenal area in Oregon.

Thanks for any help

Doug E on the Valky

[Firefighter]

If your running 3000 rpm in neutral I would say nothing is wrong, that is the way engines run without any load or weighted flywheel, but I never thought to try it myself.

[signart]

Check intake to head O-rings and vac hoses. Sounds like vac leak. Others will chime in.

[Bone]

condensation in them while sitting out in the garage

I think the moisture forms on the pipes at start-up. The warm/hot exhaust hitting the cold pipes is forming the moisture.

[Michvalk]

I think you are worrying about stuff for no reason

[kodiakfisher]

I think you are worrying about stuff for no reason

That is exactly the answer I was hoping for honestly. Having not owned this bike since new I figure better to fix small problems before they become large ones. I would feel even better to know this is just normal operation for these bikes. I figure that six carbs are rarely operating exactly the same creating slightly different combustion.

Thanks for the input. I try and be careful about emotional maintenance for the purpose of climbing to the top of the maintenance mountain for no reason. I prefer to ride rather than tinker.

Doug E on the Valky

[signart]

It's not normal. Silky smooth and flawless throughout all rpms is normal for a Valkyrie. Seriously. Even when they are not right, they're still pretty good, but it's not normal for them not to be perfect.

[Michvalk]

It won't hurt a thing to check for vacuum leaks. Maybe get the carbs synced. That's about all that will cause it, and for no more effort that it takes do those. But, I wouldn't spend any time worrying about it

[kodiakfisher]

It won't hurt a thing to check for vacuum leaks. Maybe get the carbs synced. That's about all that will cause it, and for no more effort that it takes do those. But, I wouldn't spend any time worrying about it

I believe the carbs to be synced perfectly as I used a digi sync twice to do it. In fact the RPM's went up from about 1037 to 1185 when the carbs where synced perfectly. I would not be surprised if there is a small leak in a vacuum line as they are original. Maybe that will be the next thing I tackle.lll

Doug E on the Valky 

[The emperor has no clothes]

It won't hurt a thing to check for vacuum leaks. Maybe get the carbs synced. That's about all that will cause it, and for no more effort that it takes do those. But, I wouldn't spend any time worrying about it

I believe the carbs to be synced perfectly as I used a digi sync twice to do it. In fact the RPM's went up from about 1037 to 1185 when the carbs where synced perfectly. I would not be surprised if there is a small leak in a vacuum line as they are original. Maybe that will be the next thing I tackle.lll

Doug E on the Valky 

I think that's it. 

[kodiakfisher]

So I purchased this I/S with the McCruise and it pulls a vacuum off the number 5 cylinder. Well the system is designed to bleed off Vacuum when not in use and hold/adjust vacuum when in use. I put a plug on the number 5 cylinder and almost completely eliminated any RPM wander. I wouldn't expect the RPM's to stay exact as this is driven by electronic pulses.

I just have to accept this as normal or decide what to do, but as my dad has the exact same bike and our bikes got within 1mpg all the way back from Minnesota I'm not loosing any sleep over this anymore.

Doug E on the Valky

[gordonv]

Well it sounds like you found the problem. The vacuum.

Does your CC have those check valves on the vacuum lines?

[Roadog]

  Classic symptoms of a vacuum leak.  A rolling faster than normal idle a lean condition.  Replace all the vacuum lines and check rubber manifolds too.  Keep us informed to what you find.  Might want to check plugs , you can see a lean cylinder too.

Roadog

[Skinhead]

Just a cautionary note:  If you are running the bike while stationary at 3000 rpm, I wouldn't do it for very long, especially if you don't have a large fan or leaf blower cooling the exhaust headers,  It could lead to overheating and blueing of the chrome.  This would be especially true of any single wall, non-OEM exhaust.

[chris1998]

I would check the vacuum ports on the intakes for leaks or missing. You'll see that some are plugged and one sends vacuum to the fuel petcock. This shuts the fuel off when the engine turns off. The fuel petcock diaphragm also could be leaking a little fuel into #6. Check plugs for dark deposits and the tail pipes as well. My petcock went bad years ago and I fixed by replacing it.

Chris