Vibrations...

[FJRocha]

Howdy-all,

Just recently I started noticing that Pandora is developing a pronounced vibration at 4000+ rpm, although it goes away after 4500 prm. I started noticing this about a month ago and I though it could be the tires or rough road or something like that, but I can reproduce them by just reving up the engine at any speed (yep, even at stand still). I did a carb synchronization and all the carbs are right on within spec.

Any ideas?

 

[twowheelnut]

Loose motor mount? Try re-torquing them...

 

[JSimon]

Wouldn't something like this be covered under warranty? I'd definately take the bike to the shop and have them check it out.

JS

 

[Ignacio]

....I did a carb synchronization and all the carbs are right on within spec.
Any ideas?

Carb synch? You might try a throttle body synch since the FJR doesn't have carbs.

Or if you really do have carbs that might be the problem too. Either you synched the wrong bike or you should have a serious talk with your dealer

How were the cylinders readings before and how were they after?

Two other possibilities of probably a long list that may move this thread into the never-ending recurring section:

How many miles since spark plugs have been changed? Be honest. I say this because I didn't change my original plugs until the 20K mark (I'm a bad person) and noticed new plugs did make a smoothness difference. It's OK to fib to us, but check if you're as ashamed as I was.

Air filter? I may have noticed a little smoothing when I went from a stock filter at 22K that looked reasonably clean to a K&N that was definitely new. Not as sure on this one.

 

[BlackB12]

I think it's normal actually. I noticed it a lot with heavy amounts of throttle around 4000. The engine just isn't quite in it's happy zone yet and it's just lugging a slight amount. As you found out revving it up a bit more smoothed it out. Just about every bike I've owned had a zone of vibration where anything above or below this rpm/throttle opening was smoother.

Mike

 

[escapefjrtist]

My '04 was doing the same thing. Had a really "rough" spot at +/- 4000, seemed the engine didn't want to run smooth at those revs. I've found that taking extra time and doing a really anal TBS at elevated revs (3000 - 4000) smoothed things out. Plugs were also changed at the same time, so it could have been a little of both.

Good hunting....

--G

 

[DocDanDC]

Great topic guys! The real questions are: How much vibration is too much? Where is the optimum performance zone? Does a dyno service help with this?

Anyone out there have any help.

Thanks

 

[Rogue]

"Too much" is more than you can stand. I-4's all vibrate (Buzz), but some more than others and you will have difference from bike to bike (of the same model).

So the thing is... is it to much for you.

 

[JREW]

If you just do a low speed TB sync you might miss the problem Need to do one at higher rpm, and that means adjusting the butterflies. Do a search and you will find a previous discussion and how to.

 

[FJRocha]

The vibes are not too bad, but strong enough that I can hear a rattle from the faring (Kind of like a cell phone or pager vibrating against the plastic). It goes away at any other revs, and the bike has power up-the-wazoo. Pandora is only 4500 miles young and it bothers me that it has this rattle.

:eh: I am having a moment of transcendental illumination ... now that I think of it, the rattle started after I installed the MB horns. Dang it, maybe that's what it is... Maybe the vibration was there all along, and I just noticed it now that it makes a noise.

Any whom, I'll probably re-do the MB installation and go for the "anal" "carb" synch to smooth out the vibes. (Yep, I know this last phrase is gonna stir up the pond )

 

[Bikewhore]

ear plugs! haha

 

[Centerline]

I have found a very effective method of solving my right hand falling asleep when riding the beast.

Balancing the throttle bodies did somewhat reduce the 4k vibes, but my right hand is still numbed within about 30 minutes.

Loosening my grip by dangling a couple fingers in front of the grip added about 5-10 minutes before numbing.

I simply slide my right thumb and forefinger OVER the throttle cable housing and VOILA, no more numbness at all for hours at a time. Still have fine control of throttle and front brake with that grip. No more numb hand for me!!!

 

[Claymore]

I simply slide my right thumb and forefinger OVER the throttle cable housing and VOILA, no more numbness at all for hours at a time.  Still have fine control of throttle and front brake with that grip.  No more numb hand for me!!!

+1 on that technique - works for me too! I have done 12+ hours and on the onset of any numbness I roll the thunb up as you describe. I also have a throttle rocker that I will hold with just my thumb as stretch out the whole hand - very effective

 

[TheRepairMan]

Hey Guys!

If I could find the darn web page, I'm thinking I saw a real good breakdown with pics and steps describing adjusting the "Balance Shafts" to counter this type of engine vibration. I can't be the only one here that has seen that information! :blink:

I looked again but failed to find it even by Google Search but it's out there some where and our own Mr. Warchild may have even had some part in the production.

I can't remember by whom, when, or where, but I do know the FJRs engine's Balance Shafts are adjustable and can be tuned to move that vibe to a different RPM or nearly eliminate it all together.*(see addendum below)

{Yamaha link} https://tinyurl.com/ccvty

Loosen #22 on L/H adjuster lock lever #20 and adjust #17 buy turning slightly (+) or (-) at given engine speed (see shop manual) to decrease high speed engine vibration and whine. Repeat this procedure on opposite counter-balance shaft adjuster #21 lock lever R/H side.

*[addendum]

After more extensive research in the technical department here I was able to find a PDF of the FJR SERVICE MANUAL.

https://www.paulgeorge.com/fz/doc/serv_man.pdf

In Chapter 5, pages 119-121 there are Balance Shaft installation and adjustment instructions and it appears that the adjustment changes ONLY the "gear backlash" and not the "balance phase" so I would imagine you might make adjustments for slight gear noise reduction but NOT vibration, unlike the Honda ST1300.

However, since the engine is a rigid, fully stressed member of the FJR's chassis there will be some vibration felt in the bars and pegs at some RPM. This is addressed in many forums and tech articles with additional modifications that may make these vibes less noticeable.

If the bike is still under warranty I would be inclined to have the dealer inspect it for a condition that might be considered abnormal.

Let us know how this turns out.

RogerB

 

[3dogs]

When synced the TB did you just adjust the air screws or did you really balance the butterflys on each TB? It makes a huge difference if the throttle valves are balanced at 4k. The air screws alone only change air flow at idle--not where the engine operates when you ride. I did this on my 05 and eliminated 75% of the 4000-4300 vibration.

 

[DocDanDC]

That sounds like the best idea so far. Thanks....I dont know what else to try. I think that the Yameha Service Guy at the Dealer did my TB sync at idol speed only.

Regards, Dan