Vibration at 55 (or other high gear load) SOLVED!

[caldercay]

Thanks, that ended up covering the shipping.

Understood.

They have some unique tools. I probably could have gotten away with the 4-piece drivers, but those are long blades only.

On occasion, I do a Starter Valve sync (some folks say, "Throttle body sync") on the ST, and on the CBR, I'll do a carb-sync, and in those instances, I need the "stubby" blade drivers. The way I see it, as the old saying goes, "use the right tool for the job". Many a JIS screw-head has stripped out using a Phillips driver.

Many folks would balk at spending that much on drivers. And unfortunately, you can't find JIS drivers in the US ... heck, I've spent more at the bar in a single night, so at least I have something to show for the JIS purchase

 

[dduelin]

We'd have to read the whole article, not just the Title:



I experience this. And no, it's not some "inherent twin vibration". This is under load, mostly in the upper gears.
The way that I would describe it in car terms, "it's like a V8 running on 5-6 cylinders". I certainly can't state it's as if the NC is running on one cylinder, but it sure feels like it sometimes.

I've been riding bikes ... motocross, enduros, street, 2-stroke, 4 stroke, one\two\four cylinders, in-line and V4's, for 40+ years. And I've been wrenching on cars of all configurations ... what I'm experiencing is not "normal", even for a 670cc 270 degree crankshaft-throw parallel twin Honda NC

How many lean burn parallel twin 270 crank engines with asymmetric valve timing have you owned?

 

[showkey]

How many lean burn parallel twin 270 crank engines with asymmetric valve timing have you owned?

+5 ^^^^^^^^


I might add with "overdrive" gearing in 5th and 6th. Ok near overdrive in 5th and over all the bike has "tall gearing" compared to many other bikes.......with the lowest rpm at 70 mph of any bike I have ever owned. So......many of us drive in 5th until at true highway speeds. Note my last trip yield 76.6 mpg with this shift technique.

 

[Grey1one]

The JIS drivers showed up today, pretty quick as I did not pay for expedited delivery.

 

[Little Ed]

My JIS screwdriver set is on the way as well. Thanks for the help!

 

[Wingrider]

It would be interesting to have you do a flow test into a container, to see if there is a variance in fuel flow, flow one injector for a certain amount of time, then measure the amount of fuel, then teat the other.

Must be a significant difference, between the two injectors.

 

[JDE]

Interested in hearing if you ever got around to testing the injectors and what your findings were.

 

[670cc]

Bringing up this old topic again.

As some of you may know, I own two 2012 NC700Xs, approximately 200 VIN numbers apart, probably built the same week, with around the same mileage (32-34K). You would expect the engine characteristics of these two bikes to be the same, but they are not. The one I purchased new is so smooth between 2000 and 3000 RPM, that I ride it there most of the time. The one I bought used with 29,000 miles on it is so rough at that RPM range that I avoid it. The vibrations seem to vary with conditions and throughout the riding day, but the rough one is never as smooth or sounds the same as the smooth one. I noted on one occasion last week where the rough one was literally shaking at idle while at a traffic light. That it shook at idle rules out drive train and rolling chassis components. The overall power seems fine on both machines, while the rougher one returns somewhat worse gas mileage even when ridden in a similar way. In fact, the rougher one seems to launch better off idle, but that could be just clutch adjustment. BTW, both are manual transmissions.

I cannot yet find the post, but I seem to recall the previous owner desiring a gearing change because he hated the feel of his bike below 3000 RPM. But I would guess he had no other NC700X to compare it to. Based on that, if my memory is correct, this problem may not be new.

I'm thinking the vibrations have to be about uneven cylinder performance. The previous owner (was once well known on the forum) I believe set the valve clearances and changed the plugs properly prior to the sale. And even if valves or plugs were the issue, the vibration would be expected to be more consistent than it is.

So I recalled and rediscovered this thread which seems to "roughly" fit my symptoms. Reading through it, I think it's worth a shot and I may try to replace the fuel injectors over these coming winter months.

Does anyone else have experience, comments or suggestions?

 

[showkey]

Swapping injectors from bike to bike would be an interesting experiment.

Full dose of Techron* ( before cold weather arrives) would also be good test to see if anything changes.

I am still a little suspicious of my idle air controller ( it’s a stepper motor on the throttle body) for idle and starting issues. Plan on looking at mine this winter (inspection of deposits and or smooth operation).


* Techron fuel injection cleaner.

Products


Not trying to turn this into an fuel additive debate......Techron was one of the only additives Honda recommended in their automotive FI systems to resolve drippy or leaky or poor pattern spray on injectors.

 

[670cc]

I bought a set of used injectors today off eBay for 1/4 the price of new. I will mess with them over the winter and report back on the results

I figured used ones would be ok, since well, most all NCs are running fine on used injectors.

 

[rmezei]

I would be very interested in the results myself - I can tell you my 2017 NC750X up here in Canada is doing the same thing, as soon as I pass over 60KM per hour and switched to 6th gear, she's laboured as hell until some more RPM pick up - especailly seen with the wife on (2up), i.e. more to pull. It's not something you can miss, it's pretty obvious. I always thought it was normal and the engine design - lumping.

 

[HarveyM]

Interested in the results. (Will you tell/show the previous owner if it works out?) I can't believe this is a common QC failure on Honda's part (or at least hope it's not).

 

[670cc]

I would be very interested in the results myself - I can tell you my 2017 NC750X up here in Canada is doing the same thing, as soon as I pass over 60KM per hour and switched to 6th gear, she's laboured as hell until some more RPM pick up - especailly seen with the wife on (2up), i.e. more to pull. It's not something you can miss, it's pretty obvious. I always thought it was normal and the engine design - lumping.

That symptom you describe is normal behavior for a 700 (but I couldn’t say if it is on a 750). It is not the same symptom and it is not the problem I’m trying to address.

 

[rmezei]

Got ya ! I did read the whole thread here so I see what you mean ... good luck

 

[marky777]

I think I have this problem.

Which youtube videos did you watch that you mention

 

[frog13]

Any resolution to said issue (s) 670cc.

 

[MalcolmReynolds]

That symptom you describe is normal behavior for a 700 (but I couldn’t say if it is on a 750). It is not the same symptom and it is not the problem I’m trying to address.

Might I also add that 60km is 37 mph. 6th gear at 37 mph the bike is LUGGING. So what 670cc said is true, this is normal behavior.

670cc did your replacement injectors do the trick for you?

 

[frog13]

Undoubtedly agree with MR above. 6th gear at 37 mph is ridiculous, who would operate there......mpg mean something, but ......c'mon.

 

[dduelin]

Ridiculous for sure but Honda says it is OK. Page 41 - 42 in my owner's manual. I have owned Honda motorcycles for 48 years and the owner's manuals always have crazy low minimum shift points. Don't worry about it.

 

[670cc]

Might I also add that 60km is 37 mph. 6th gear at 37 mph the bike is LUGGING. So what 670cc said is true, this is normal behavior.

670cc did your replacement injectors do the trick for you?

Fuel injectors were changed and made absolutely no difference to the engine behavior. So I guess they were good before and they’re good now. I’m beginning to think that the aftermarket handlebars installed by the previous owner are largely responsible for the “feel” of the bike. The internal and external handlebar weights are gone.

In response to the other comment, I even run my NC at 1500-2000 rpm on rare occasion. Depending on the situation (gear, load), it’s not lugging it.