X over

[rossi46]

Hi Is a X over the way to go in a bid to rid me of the sneeze when on steady throttle and about 4000rpm? I have Mistral cans so would this make the bike run lean? would I be better waiting for the funds for a PC? thanks

[Admin Jaap]

It didn't do anything for my sneeze. Balancing the throttle bodies and setting the tps right cured my sneeze.

[fotoguzzi]

a mistral x over fixed that exact thing for me.. I'd do that before a pc3.

[Trevini]

Never had a sneeze, but I have Mistral cans and x over and it runs sweet.

[aerodyne]

I found carefull attention to balance of butterflies and setting TPS almost cured the sneeze for me, I finally opened up the clearance on valve backlash fractionally and totally cured. Cans on my bike are totally straight through specials I made up myself.

[makarushka]

Can anyone here please describe and quantify this "sneeze" a bit further? On the new-to-me Rosso Mandello this torque drop right around 4000-4200rpm -- if it's just a torque drop in fact and not something else -- is about the worst single thing about the bike that I am still very uncomfortable with. It manifests itself in the highest level of vibration, if not to say, knocking, felt through the handlebars and the bike body.

 

The bike, when I purchased it a few months ago, was serviced as per the factory, which did not do it much good in regards to this "sneeze" issue, then the valves were set to Raceco spec and the throttle bodies were synced according to Micha's method. This helped quite a bit with rough running under 4K, though new flat spots surfaced, but the 4K problem stayed nearly the same. Then a Mistral crossover was fitted and it was yet another improvement across the board, which also diminished the amplitude and intensity of the vibration at 4K but it is still quite alarming to me I have to confess. I now also have a FactoryPro Teka controller but the bike is yet to be dynoed with it as the original tuning attempt was not very successful and all these mods took place afterwards.

 

I did research the forum extensively but have not found too many accounts where people actually try to quantify just how bad this 4K phenomenon is (or seems to them). Most seem to talk about the torque drop under 3K or 3500 but for me personally it is this very specific point at 4000 or 4200 (as per Veglia) that worries me the most. I would very much appreciate any input and advice on this issue. Do I just need to get used to this and forget it? Or is this thing going to fall apart in the nearest future, as that is how it seems at times?

 

Thank you!

[rossi46]

makarushka mine is also at the 4000-4200rpm when on a steady throttle, riding in traffic, it feels like a cough as though the bike is sneezing! fine above or below this rpm and also when accelerating past these revs- I think its time to visit my mechanic all that tps stuff is beyond me

[Tom M]

I now also have a FactoryPro Teka controller but the bike is yet to be dynoed with it as the original tuning attempt was not very successful and all these mods took place afterwards.

 

I did research the forum extensively but have not found too many accounts where people actually try to quantify just how bad this 4K phenomenon is (or seems to them). Most seem to talk about the torque drop under 3K or 3500 but for me personally it is this very specific point at 4000 or 4200 (as per Veglia) that worries me the most. I would very much appreciate any input and advice on this issue. Do I just need to get used to this and forget it? Or is this thing going to fall apart in the nearest future, as that is how it seems at times?

 

Thank you!

 

Is your 4k rpm issue vibration only or does the engine actually "cough" or miss a beat at that rpm? Do you get a rattling noise? Does it happen at small, large, or all throttle openings and in all gears as the tach passes through that rev band?

 

If it's just a vibration issue make sure all of the engine mounting bolts are tight then consider adding a set of heavy bar end weights to your handlebars. Are your bars stock and do they have the weights installed? I bought a set of extra-heavy bar weights from Moto International after I changed over from the stock clipons to a set of standard handlebars and they helped a lot with vibration.

 

If you have a cough like Rossi46 has it sounds like you have already addressed the throttle body balance, valve adjustment and TPS setting. Assuming that those were all done correctly I'd wait and see how things go on the dyno since you have an aftermarket EFI adjuster that could be causing a problem there. If it's lean there that should show up on the dyno. Be sure to ask the operator to do a few partial throttle runs to try and duplicate your problem at that specific RPM and whatever specific throttle opening you feel the problem is most common.

 

If it's a rattling noise that happens at half throttle and above only in the upper gears then it may be detonation or pinging. My bike did this badly when I first bought it but it was at 5k rpm not 4000. If this is the case I found that a good decarbon procedure helps a lot. Adding a full can of Seafoam to a tank of gas seemed to help but injecting it into the intake manifolds per the instructions on the can helped more. Octane booster might help too.

 

Good luck with it!

[makarushka]

Is your 4k rpm issue vibration only or does the engine actually "cough" or miss a beat at that rpm? Do you get a rattling noise? Does it happen at small, large, or all throttle openings and in all gears as the tach passes through that rev band?

 

As best as I can tell, the issue is vibration only. Happens in all gears and seems to intensify with the actual load -- say, going uphill vs. even surface -- though I also try not to push it right at that spot specifically due to the extra vibration it produces. I'd say it happens regardless of the throttle opening but I need to further examine that to be sure.

 

If it's just a vibration issue make sure all of the engine mounting bolts are tight then consider adding a set of heavy bar end weights to your handlebars. Are your bars stock and do they have the weights installed?

 

My bars are the stock clip-ons. Until yesterday I had the stock weights, even though I had purchased a set of Manic Salamander's; I just wanted to do all the standard tuning first, and one thing at a time so I could better understand the effect of each procedure. Yesterday I finally added these weights and they did help quite a bit but the problem is still in the realm of uncomfortable, akin to having dental work where there really isn't any pain but vibration is nonetheless playing tricks with your head

 

Thank you very much for all the help and suggestions. I apologize for hi-jacking the thread, as after Tom M's comments I believe it is not the same issue as the OP is experiencing.

[fotoguzzi]

makarushka mine is also at the 4000-4200rpm when on a steady throttle, riding in traffic, it feels like a cough as though the bike is sneezing! fine above or below this rpm and also when accelerating past these revs- I think its time to visit my mechanic all that tps stuff is beyond me

perfect discription of how my bike ran before the M crossover, a close scrutiny of the TB balance and having the VDST program has pretty much solved it for me.. still hesitates in the morning until the crossover warms up to temp.

[Tom M]

As best as I can tell, the issue is vibration only.

Yesterday I finally added these weights and they did help quite a bit but the problem is still in the realm of uncomfortable, akin to having dental work where there really isn't any pain but vibration is nonetheless playing tricks with your head

 

That's not vibration, it's character!

 

Is this the first large displacement twin that you've owned? I think all the big twins that don't have counterbalancers will have a noticeable vibration at a certain rpm. I don't know if that holds true for the boxer beemers since I've never ridden one.

 

The V11 definitely has some vibes at 4k rpm and it smoothes right out at 5k rpm. I believe I've read here that the pre-2002 clipons might transmit a little more vibration that the later bikes get too. That said, I do most of my cruising right at 4k and the vibes don't bother me

 

If everything is up to snuff on your bike and you still can't stand the vibes maybe the V11 is the wrong bike for you?