May have revved to high, performance issue under full throttle

[CG]

Well,
Ran into a group of bikers that didn't seem to want me to pass? I really got on it and possibly may have exceeded redline, don't know and passed the group of "twins" .  After that, my valk didn't seem to have the punch on the way home.  Here's a recap:
1. idles fine, also seems to rev just fine in neutral
2. all cylinders on both banks were firing(pipes hot) when I got home. (boil tsp water on each)
3. however, under full throttle valk seemed to vibrate/shake a little with reduced performance.  I'd say it was about 85% to 90% but a noticeable performance hit.

Net: something seems to have happened since I got on it today.
Valk has 25k miles
petcock replaced last year / seafoamed
Plugs replace at that time
Also adjusted valves then
It's been a smooth, powerful valk with no issues up until that event.

I'm hoping I didn't smoke a valve do to high revving.  During the pass and afterwards there were no apparent symptoms, with everything silky smooth as I continued on my way.  It's just when I layed into the throttle again, I noticed a bit of vibration and a perceived lack of performance. (Trying to beat the rain home:)

Not sure where to start?  valve, timing, perhaps as simple as carburation. Thanks in advance for the help!

[John Schmidt]

Vibration? I think I'd check the driveline first....u-joint, etc.

[Mr.BubblesVRCCDS0008]

Bike has a rev limiter so you shouldn't have hurt anything. I've hit mine several times. Vibration isn't a good thing check u joint and driveshaft and coupling.

[wiggydotcom]

What John said... especially if it revs ok in neutral with no vibration.

[CG]

Thanks to all for your input.  Couple of additional points:
1. Bike only has about 25k miles
2. I don't ride it hard and I've never dumped the clutch
3. When I hit the gas to pass them(in first gear from a light), the front end came off the ground
    Point being, very powerful, very smooth/responsive, all there.
4. When I hit the gas harder now, it feels more like a twin vs. smoothness of a six.  Point being, if I'm just pleasure riding, no noticeable issues.  It's only when I roll on the throttle, say 60%-70%, do I feel like it's missing as it's not smooth like it was.  Performance is definitely impacted.

If it's drive train related, wouldn't I feel it at all times.  Again, if I'm in 5th gear doing 60 pleasure riding like, it's flawless.  It's just under rather quick acceleration do I feel a bit of a "pulse" and a lack of performance.  I did change the oil recently and accidentally used honda's oil with Molly.  How ever my understanding is Honda's oil is relatively low in Molly(PPM) and the clutch isn't slipping.  Again, I just feel this pulse like feeling under acceleration with poor performance.  If we still feel as though it's drive train related, I will start there.  Thanks again guys!

[BonS]

I'd check the plugs. I've coughed up a bit of carbon perhaps and bridged a single plug. Compared to the silky smooth power that we're all used to it felt anemic and shook a bit.

[wiggydotcom]

It'd never hurt to add some Techron to your gas tank.. Try half a can and see what happens.

[Hoser]

Rev limiter kicks in about 6500 rpm, it sounds like you your running on about 3 cylinders when it comes in.

[Patrick]

What speed did the engine hit ? As said, the rev limiter should have stopped it from going too high. These engines are about as bullet-proof as one can get and that shouldn't have hurt it. Usually when these monsters have a high speed issue, its fuel delivery. Just because work was performed on the petcock a year ago doesn't mean its not capable of causing problems now. Also check the vent line and vacuum line. The easiest way to check to make sure the engine is OK is a compression check.

[CajunRider]

If you losing only about 15 - 20%, you may have a broken spring of torn membrane causing the slide to no operate properly.  A hard run like that may have made the slide open farther than normal causing a break somewhere. 

So, if the fuel lines and vacuum lines check out OK, check the rubber membranes in the carb vacuum chambers.  The springs are right on top of the membranes, so you'll be able to check those at the same time. 

[CG]

Lots of great input thus far and thanks!  Some responses to your questions:
The rev limiter never kicked in. I don't know what the tach read at the time I shifted.  I only reached third gear and I was past the group of bikes.  Top speed isn't the issue here.
All I know is before the incident, it would take a health dose of throttle, very lively and very smoothly.
Now it's a bit rough and lazy under heavy throttle. There was about 100 miles or more on this tank of gas, when this happened. I filled up after that, on the way home as it felt like it was running out of gas(after the incident).
Maybe sediment or the like got sucked into the petcock, into the fuel delivery system.

There was about 100 miles or more on this tank of gas. I filled up after that, on the way home as it felt like it was running out of gas.

Which leads me to believe the valk now behaves like it isn't getting enough gas, since I opened her up on the way home that day.
- in checking the the carb vacuum springs and membrane, not sure how to do this? Can it be done without taking the tank off by simply taking the "caps" off the carbs?
- Vent and vacuum line, any hints on location/identification?  Am I just looking or splits/cuts, etc.?

[CajunRider]

- in checking the the carb vacuum springs and membrane, not sure how to do this? Can it be done without taking the tank off by simply taking the "caps" off the carbs?

Exactly, just take the caps off the top and check the springs and rubber membrane for breaks/cuts. 

You may have to loosen the tank and raise it an inch or so.  I don't remember for sure. 

- Vent and vacuum line, any hints on location/identification?  Am I just looking or splits/cuts, etc.?

Correct again... these bikes are getting some age on them now-a-days.  The rubber hoses are beginning to split/crack. 

The easiest way to check is to spray some sort of flammable fluid around the hoses connected to the carbs, but not near the air intake on top the breather box.  I have used WD-40 for doing this to dirt bikes back in the day.  I've even used ether before, but that can get a bit more risky.  If you get a change in rpm, you know the system is sucking air into the engine from places other than the breather box... and that causes a lean condition and "rough" running. 

Also, the chrome intake tubes between the carb and the engine heads have o-rings under them (against the engine head).  This is another good place to check as the age is starting to make a few of these o-rings crack/shrink enough to leak. 

[CG]

Ok, thanks for the clarification cajunrider.  Looks as though I have a bit of homework.  I'll get some seafoam into the tank and run it close to dry before trouble shooting, in case the tank needs to come off at some point. If that doesn't solve the problem in a while, I'll then check carbs, then hoses/connections as outlined.  Being that the engine is quiet, with all cylinders firing, I believe it is fuel system related, just need to determine if dirt or sucking air from additional spots is the culprit.  Based on your help you've provided, think I can do that at this point.  I'll provide status updates as I go..

Thanks to all for your help.......Tried to insert photo to show you what I'm working on.  I'll figure that out later

[Hoser]

Lots of great input thus far and thanks!  Some responses to your questions:
The rev limiter never kicked in. I don't know what the tach read at the time I shifted.  I only reached third gear and I was past the group of bikes.  Top speed isn't the issue here.
All I know is before the incident, it would take a health dose of throttle, very lively and very smoothly.
Now it's a bit rough and lazy under heavy throttle. There was about 100 miles or more on this tank of gas, when this happened. I filled up after that, on the way home as it felt like it was running out of gas(after the incident).
Maybe sediment or the like got sucked into the petcock, into the fuel delivery system.

There was about 100 miles or more on this tank of gas. I filled up after that, on the way home as it felt like it was running out of gas.

Which leads me to believe the valk now behaves like it isn't getting enough gas, since I opened her up on the way home that day.
- in checking the the carb vacuum springs and membrane, not sure how to do this? Can it be done without taking the tank off by simply taking the "caps" off the carbs?
- Vent and vacuum line, any hints on location/identification?  Am I just looking or splits/cuts, etc.?

The bike will hit the limiter in any gear, not just 5th.  Hoser

[longrider]

It will not hurt to add some fuel conditioner to her.  However before you start taking things apart start with the easiest and quickest.  Replace your plugs and take her for a spin.  Sounds to me like she has a miss when the cylinders load up with fuel under full throttle.    rev limiter is 7250 and I've been there a few times.  You will not hurt the engine by hitting it once in a while.

Warren

[custom1]

I would agree with changing the plugs. They are cheap and easy to get to. I had a bad plug in a car a few years ago act just like you are describing. It would idle fine and run good at low load, but would misfire at higher load and speed.

If not the plugs then I would also look for a vacuum leak.

As far as fuel delivery, I don't think what you're describing is a fuel delivery problem. Usually the bike will run fine at high load for a mile or two till the bowls run dry then start to miss.  I'm talking about petcock fuel delivery here.       

 Now a problem with one carb spring or diaphragm is possible as mentioned above. All six could be working fine in the low circuits and only five on the high. Losing a cylinder above half throttle or so would feel the same as a missing plug at high load.

[Ricky-D]

I wouldn't even consider the slide springs or diaphragms are any part of the problem.

The slides are vacuum operated and are full open every time you turn the throttle (full on) for a second or two.

You can damage the vacuum diaphragm easily trying to remove one and they are expensive to replace.

Look at every other possibility before messing with the carburetors.

***

[CajunRider]

Spark plugs... good point there.  I hadn't thought about that. 

That's a GOOD one to check.  I have a Triumph that was hard to start when purchased (used).  I let my mechanic give it a once-over to make sure I could trust everything before i rode too far. 

The plugs was one of two items he found... it ran MUCH better after he put in new plugs. 

[CG]

Cajunrider, thanks for your continued involvement.  Ricky D, custom1, hoser and everyone else,
I do value your support here.  Actually, while the problem isn't quite solved as of yet, we are getting closer with all of your help. 
- Ruled out anything major/mechanical(thank god!)
- have isolated the issue down to either a plug or fuel delivery or vacuum issue

Attack plan
- I've mixed seafoam into the gas and put about 20 miles on it.  Honestly, with limited miles(20) there seemed to me marked improvement.  While still a bit lazy, it seems to be getting smoother.
- I plan on running the rest of the tank to note the impact of the seafoam.

- If I still have problems, next step I'll replace the plugs, although I did them last year(about 5k miles ago). I will then note the impact if any.

- Then I'll begin spraying carb cleaner, WD or ether on the hose connections of the carbs and around the intake manifold where it meets the engine, looking for gains in RPMs during idle, per the previous suggestion.  This should show me if it's sucking additional/unwanted air from anywhere, vacuum leaks etc.

As you can see, sticking with a previously suggested plan of starting with the easy stuff first, progressing to more technical stuff as necessary.  Like I said, the mere fact that we've eliminated many things already is progress in and of itself.  I would already have the tank run through her if the weather would cooperate.  And again, it does seem to have gotten smoother already as I don't notice the missing or pulse feeling as much, although it does seem like it takes awhile to rise to speed, compared to what it was.  However, having said that, I ran her up to about 105 this afternoon, not sure it would have done that before as it was really lazy in attempting to gain speed.  I poured the seafoam into the tank, and shook the valk considerably before taking her for a ride.  Then I got her out on the highway and let her spread her wings a bit.  On the way home, it did seem considerably better as I've stated.  We'll see how this unfolds over this week.

Until then, thanks again VRCC!  Any of you going to Inzane?  I'm thinking beer time:)

[Bradb]

CG I'm having sort of the same problem with my interstate let me know what it is when you figure it out please I'm troubleshooting my self right now. I have a pingel valve on mine and I wondered if it wasn't delivering enough fuel at the time she's wanting it like u said. If I can help I sure will! Be safe.

[longrider]

In my past experience I have seen a new plug fire sporadically.  Mileage of the plugs does not matter. They are easy to replace, inexpensive, and may be your problem.  The use of a fuel conditioner may clean the electrodes a bit and the m/c may run better but if it is a plug problem it will not cure the issue.

[BradValk48237]

Petcock.....

Brad

[Ricky-D]

Regarding any petcock issues, it's very easy to check if indeed the petcock is the problem.

Simply take the gas line running from the petcock and run the gasoline into a measuring cup.

If you are seeing more than 4 ounces filling the cup in one minute, you can expect that the petcock is not the problem.

***

[CG]

VRCC gang is the greatest!  Everyone's support is heart felt.....Well, I really didn't give the petcock much consideration, being that I replaced it last year(Stock Honda part). 

Out for a ride, just putting gas through her, I was thinking about everyone's input, especially the last input from Brad.  So, I shut the petcock off all together and let the valk all but quit.  Then I moved it to reserve and waited for it to come alive again.  Once it did, I hammered her and the fat lady took it in stride.  Smooth and powerful.  I hammered her again, several times with the same outcome.  At this point, I at least know it's the petcock but keep in mind, I'm still on reserve and all is still good.  I then moved it back off reserve to normal run position and road it a couple of miles.  Then once again, I hammered her and she was fine.  I will tell you I never use the petcock, usually just leaving it in the run position, which I know is wrong, expecially considering the hydra lock issue.  For now all is good again having manipulated the petcock as outlined.  If it happens again, I will do the same, hoping for the same outcome.  If that happens, I will replace in favor of the pindle(sp) variation.

Net: hopefully we've found the problem, again with everyone's help.  Thanks again!  Anyone going to Inzane? 

[fantsybikr]

I would be surprised if you hurt the motor...not saying impossible but rev limiter works on mine

[Oklahoma_Valk]

May I quote the late great Valkpilot: "Petcock. It's always the petcock."

[Jess from VA]

May I quote the late great Valkpilot: "Petcock. It's always the petcock."

Thought that was Bill Clinton that said that.   

[pancho]

Yeah,,,,  he was first