2014 Stumble on accel.

[ionbeam]

As one reference point, my '15 is pretty well balanced up to ~5k rpm. Much, much better than my '04 was without major intervention.

 

[Bill Lumberg]

I didn't really get what others were talking about about vibration before. One of my advisors told me I must just be less sensitive to the wicked vibes. I didn't get it because I didn't have them. Now I get it. Wicked vibe at speed. It makes me wonder if I could have done the TOH/SS1K run with bars like this.

 

[HotRodZilla]

WTF?? Seriously!! You need a new bike.

 

[HotRodZilla]

Have you double checked the torque on your engine mounting bolts? If those things are slightly loose, the bike will exhibit a lot of vibration. On the GEN-II anyway. I'd check them if I were you.

 

[NTXFJR]

I wonder if they did a decent tbs on those new throttle bodies?

 

[Bill Lumberg]

I need to do both.

 

[Fred W]

A couple of thoughts:

Bill's bike didn't have vibration before the TB replacement and it does now. I don't see how or why they would have messed with his engine mounts when replacing the throttle bodies.

The TBS is very simple to do on a Gen 3. You can only adjust the air bypass screws, and you do that at idle speed. But the amount of air the air screws bypass is tiny in comparison to the air flow past the throttle plates once you crack the throttle open. So those adjustments at idle have little effect on the balance much above idle. In other words, you can mess with the air screws until the cows come home and it won't affect the vibration at 4k and up.

The throttle body assembly replacement sure fixed mine. Only downside is my bars are way more buzzy than before. Now I understand what people talk about. Before, I had almost no buzz. Go figure. Good luck, Steve.

Even though you can't adjust the throttle bodies it would be really interesting to hook up a Carbtune (or whatever) and note the results at several RPM.

At least you would know if you had a problem there..............

^^^ This is a good idea. And furthermore, you could use the same technique that I developed in the RDCUA TBS procedure to characterize how far out those throttle plates are unsynced from each other.

Just close down all 4 of the air bypass screws and whatever misbalance you have at idle (and above) is all attributable to the throttle plates not being perfectly aligned and passing the unequal amounts of air. You can't do much about it, but you can measure how different they are in vacuum pressure.

edit - It is possible that you could have an air leak that is misbalancing the throttles. If you did the above, you would want to closely inspect the hoses and fittings on the throttle body that has the lowest vacuum level with all of the air screws closed.

 

[wheatonFJR]

As one reference point, my '15 is pretty well balanced up to ~5k rpm. Much, much better than my '04 was without major intervention.

How is it at 7500-8000 rpm Alan?

 

[Gary B]

There is a warning not to touch the white painted reference bypass screw in the Gen III OEM manual..'otherwise the engine may run roughly at idle and the throttle bodies may not operate correctly'.

Not exactly sure why that would be, would need to read more about the fuel injection system.

On my last , and only, TBS I could not adjust the other three screws to the reference (No 2 on mine) so I got them as close as I could without disturbing it. It's happy enough.

 

[Bill Lumberg]

I don't think it's the problem, but as soon as I find the torque values again, I'm putting a wrench on the engine bolts because it's time. I haven't checked the ones below my knees since I put sliders on.

 

[Fred W]

There is a warning not to touch the white painted reference bypass screw in the Gen III OEM manual..'otherwise the engine may run roughly at idle and the throttle bodies may not operate correctly'.
Not exactly sure why that would be, would need to read more about the fuel injection system.

That's a crock of ****. You can test it yourself. The white painted "reference" screw is (will be) the only one that is fully seated CW. Check it out on your own.

They just want you to allow the least possible bypass air so that the ECU idle control will have the most possible range of idle air adjustment. No real magic here.

If you want to do it "like the factory", close all 4 air screws fully, then use the one with the lowest vacuum as the new "reference" whether painted with the special white-out or not, and open the other 3 screws only as much as you need to to match the new reference.

Boom.

 

[Fred W]

I don't think it's the problem, but as soon as I find the torque values again, I'm putting a wrench on the engine bolts because it's time. I haven't checked the ones below my knees since I put sliders on.

Bill, it's not the torque values that are significant. It;s the order that you tighten them that is. It can (or ideally won't) put stress on the frame due to that order. There have also been folks that have theorized that one should fully heat soak the engine and frame before doing the engine mount tighten-up, since the dimensions can change as they heat and expand at differing rates.

I believe that all of the left side mounts are direct to the engine and the right side mounts are clamps onto a floating mount. (If that is correct) You'd want to tighten the left side mounts first and the right side clamps second to get the least "stress" on the frame, but only at full operating temps when all parts have reached dimensional equilibrium.

 

[dcarver]

edit - It is possible that you could have an air leak that is misbalancing the throttles. If you did the above, you would want to closely inspect the hoses and fittings on the throttle body that has the lowest vacuum level with all of the air screws closed.

Another thought. If the air box isn't fully seated onto the TB assembly? I now have 2 gen 2 air boxes. In each one, cylinder #2 rubber boot is marginally shorter than the other three. On first assembly, not fully seated with resultant air leak and increased vibration.

Like this.

 

[stevec677]

Yamaha replaced my Throttle Body Assembly the other day (thank you YES). I've only had the time/weather to put about a hundred miles on the bike since getting it back. My problem was a little different then Bill's. It was completely intermittent and impossible to reproduce on command. It happened mostly at a constant throttle (rpm did not matter). It would go away during acceleration. The bike seems to be running perfect now, but I want to give it a little more time before I consider this matter resolved.

 

[Bill Lumberg]

Yamaha called for my old throttle body assembly not too long after I cleared the shop from my replacement... So no surgery.

 

[stevec677]

Same here. Yamaha is sending my old Throttle Body Assembly back to Japan to see if they can identify the failure. I asked if they would let me know what they find.

 

[Bill Lumberg]

I'm wondering if this isn't more common than we suspected. Last time I had to wait that long for a warranty part for a pretty new vehicle was because there was a recall due to part failures. It's fairly expensive. I can see why they'd limit publicizing it. Time will tell.

 

[RaYzerman19]

Rats.... we may never find out the true root cause, which may be different in those two cases. I know of another case of constant high idle where initial indication is that one of the four butterflies is not closing completely (can't be sync'd) and likely a TB replacement will occur there.

 

[Fred W]

Is the cylinder that can't be synced too high or too low vacuum? Assume low since you said you thought maybe the throttle valve isn't closing. May be more likely is a vacuum leak somewhere on that TB.

Also, if it is too low, just make that one the new "reference" and open the other 3 screws to match that one. IOW, ignore the factory white paint.

 

[RaYzerman19]

Nope, butterfly is not closing, sync not possible. Physical issue. All ofher three are closed...... awaiting further analysis by dealer. That's all I know. Common shaft, shouldn't be.