NT700VA, engine noise...

[ST1100Y]

I'm not so used to a 2-cyl engine to know what's normal or not... (the V4 16-valve in the ST is smooth as an EV...)

That the NT is a bit rumbling till ~2800rpm seems normal, it gets more lively and sounds "happy" >3000rpm, but ~4200rpm it starts to emit a harsh sounding "knock" when opening the throttle?

It calms again once it reaches 5000, but I hesitate wringing it that far due the harsh sound above 4000...

Idle is smooth, no ticking, no abnormal noises, no loose heat-shield, no unfixed fairing parts flapping around...

I do intend to replace air-filter and spark plugs though...

 

[Phil Tarman]

That the NT is a bit rumbling till ~2800rpm seems normal, it gets more lively and sounds "happy" >3000rpm, but ~4200rpm it starts to emit a harsh sounding "knock" when opening the throttle?

It calms again once it reaches 5000, but I hesitate wringing it that far due the harsh sound above 4000...

I've never heard anything like that in 145K on two NTs.

 

[rc_heli_nut]

I've never heard anything like that in 145K on two NTs.

Me neither, but the NT engine is not electric motor smooth or an inline 4 either. It's a v twin without counterbalancers, so it will always have some degree of shake.

It does have a bit of an "agricultural" charm to it, more like a plow horse than a race horse, and I mean that in an endearing way. Rotella quelled some of it.

 

[WVRider]

I can't imagine an issue. As noted, it's not like a V4 or Inline. If it's not rattling just off idle and is smooth at high rpm, just ride it. Where I like to listen, get it up to about 80mph, then duck down behind windshield, flip up chin piece on my modular helmet, and that baby is puring like a kitten. Just did that this weekend as it rolled over 83K miles on a long straight. Love that sound. Ride it like ya stole it.

 

[harryhendo]

It seems that the sweet spot for the NT engine is above 3K RPM and then it settles into a nice purring sound at 4K. Above that, it starts to growl a bit up to 5K, and then smooths out again above 5K. It does this on both of my NTs. I've checked the valves on both and they are in spec. So I think it is just the characteristic of the engine. I had an old R65 BMW that had a total flat spot at 4K, so you had to ride it below or above (usually above) ;-).

 

[cliffh]

I've noticed that "knock" also. Funny thing is, when that is happening, lower you head down to the clean air behind the windshield and the sound goes away. I figure it must be some "harmonic noise" reflected from the windshield and not an actual knock.

Cliff

 

[ST1100Y]

Well, new air filter and spark plugs... smooth again...