Chasing that elusive vibration

[macx]

Still trying to minimize the handlebar buzzing that puts my hands to sleep in fairly
short order, even with foam sleeves & gloves and not a tight grip.

And recently have developed a very noticeable surge - intermittent loss of power -
under higher rpm and heavy throttle, so something definitely amiss. Runs with no
surge at all at idle and steady regular road cruise speed and normal acceleration, just
bucks under heavy throttle like there's either a weak plug or coil or partly plugged filter.

Had the bike a year now, got it last summer used. Studied up on the model,
looked thru a lot of the service info on this forum and got a big svc manual,
went thru the bike pretty much stem to stern servicing and checking tuning.

Set the rockers and valves - they weren't "out of spec" but definitly not set
to close matching tolerance (rechecked awhile ago, just fine), synchro'd the TB's -
that helped a little on the vibration and the engine response -

Hooked up the twin-max today and set it at max sensitivity and the needle hardly
moved off zero the width of the needle at idle and at varied rpms up to over
4k, including hitting the throttle hard from idle. (I had done a very careful job
when I first did that.) So that should be OK.

Then also today had time to check the TPS for the first time, that's right at .38 at closed throttle -

Got new plugs coming - had a surprisingly hard time finding them around here.
Neither O'Reilly's or AutoZone could even order them in either Bosch or NGK.
Didn't want to mess with the wrench issue with the Autolites. Have read posts
on both sides of the Autolite vs stock plug issue - some saying the Autolites
run better, some that the Autolites ran crappy and the stockers ran good.
And there are desirable and proven features that have come along in the last
few years that "standard" plugs, Autolites included, don't have. Like sharp edges
center electrode - i.e. star shaped or something like that with lots of sharp edges
that help spark jump, a thinner side electrode with different placement relative to
the center, and some other things. So - -.

Finally found that Advance could order them (this was last Sat) and I'll have them
NLT Wed. I've put about 6k on the bike since I got it last August, and it had
25k on it then. Really don't know if it's had new plugs or when - took them out
when I went over it when I got it and they looked fine, incl the gap, so put them back in.
Center electrode still nice and flat and not rounded, and side electrode not eroded away
and nice and flat with square edges, and good coloration, etc.

Used to cars with electronic ignition where the plugs last well over 50k - both my
wife's old car and her current one say change plugs at 100k (course that's the
high $ ones), and my hot rod has had the same plugs for about 35k and they're
in excellent condition. (Tried the AC RapidFire after a bunch of research on
spark plug technology and recent developments, reasonable cost and yet have the
important hi-tech features like star shaped center electrode, small side electrode, etc -
they're doing great in my hot rod, and it gets driven hard. Better mileage, too.
Anyway - some day I'll check to see if there's a cross for them. For now, the stockers.)
So didn't give 25k a whole lot of thought regarding plugs when I got the bike, guess I
just missed the recommendation to change at more like 12k. Could be they're overdue
for a change, breaking down under the higher combustion pressures of heavy throttle,
so we'll see if that helps any.

Have a fuel filter, wife is picking up an O ring for me and I'll change that when I'm
home this coming weekend. That very well may be the original filter. While I'm
at it, new efi hose and clamps and the good QD's are going on, and an external filter.

After all that, about all that's left is the stick coils, the bucking under heavy throttle
may be due to one of those being weak. By luck, found a low miles used one for
$15 less than half the cost of a new one, shipped, so that's coming. Then I can
swap out one at a time and see if there's any change. If the fuel filter hasn't already
fixed the problem. If I don't need it now, at least I've got a relatively inexpensive spare.

Of course the first priority is to get rid of the surging and power loss under heavy throttle,
but I'd also like to reduce the buzz in the bars from 3600 thru 4300 or so. Am getting
bar end weights so that should help whether or not there's something in the engine tune
that is contributing to the buzz.

Then this winter the RTP trans and a higher geared final drive to put the engine at the sweet
spot at the mph I do by far the most of my driving and eliminate the big drop from 5 to 6
which now forces me to run it up into the buzz range in 5th or lug it, or shift up and down
frequently.

The adventure continues! :-)

[Arbee]

Sounds like you have covered all the bases except one...

Physics

A horizontally opposed twin cylinder engine will never be as smooth as a 4-in-line Japanese.

What was your previous bike??

[macx]

Oh, I'm well aware of that.

Kinda just wish I'd have known about the R1200 with it's balance shaft
engine when I bought this, but oh well -

I know there's only so much you can do, so that's why I'm playing around
with the gearing to get the engine running 3k to 3.5k at my prevalent
road speed of 55 to 62 - that will be in 5th, leaving me 6th for up to
still nearly 75 without getting into the worst of the buzz range.

Well, let's see - other bikes.

Started with a 500 Triumph (yup, I'm an oldy but a goodie, at least I think
so , along the way had a 53 Harley side shift (wish I still had THAT one -
for it's collector value), a 750 Norton semi-chopper, a couple other not
worthy of particular note, and the last one before this BMW was an
81 Suzuki GS750EX that I last rode in 92 (!) - when I started to travel
all over the country for my work and hadn't stayed in one place long enuf to
take the bike with me. This job I knew was going to be nearly 2 years, and
I had a lockable garage for the first time on the road, and fairly close to
home, so decided to dig it out and resurrect it (tires, gaslines,brake hoses,
valve springs, stuff like that) but a friend at work talked me out of it so I
sold it to him. On a trip to see our daughter in CA, my son in law
(1000 Ducati Monster - NEAT bike but a tad too "young" for my old knees
and back) took me to Arlen Ness's shop and museum nearby where I saw this,
and pretty much for a very decent price and my wife "made me buy it" (really!)
so bought it on the spur of the moment. Most likely wouldn't have gotten
this exact model had I been looking for a bike, esp with no BMW experience
at all, but here I am, "for better or worse" -

[sjbmw]

I switched to Amsoil last week, (24k miles), and I am amazed how much smoother the engine is.

Quicker starts under 60F, and overall less vibration across the entire power band. The roll on power jumped also. It just feels better. MPG went up also.

[macx]

I've used full synthetic in everything I own for a number of years,
ever since I had first hand experience at how effective it was in
a variety of applications (like heavy truck trans & diff's) and a couple
cars of mine that had well over 200k on them and still ran good and
didn't usually require any added oil in under 3k miles, usually of fairly
hard driving.

There are small differences in the additive packages between the various
good synthetics, but I think any of them are just fine.

I've tried several different brands in my bike - mostly because of what's
available when I need it rather than driving an extra bunch of miles
just to get a particular brand, and in a couple of vehicles and could tell
no real difference between them, but sure can between synthetics and
regular petro based lubes & oils, even the top quality brands.

[jm1515]

I switched to Amsoil last week, (24k miles), and I am amazed how much smoother the engine is.

Quicker starts under 60F, and overall less vibration across the entire power band. The roll on power jumped also. It just feels better. MPG went up also.

I'll bet your teeth are whiter, you're sleeping better, and you don't need those Enzyte pills anymore, either....

[snowprick]

Did you balance your wheels? If so how did you do it.

[macx]

Nope, that's pretty clearly not the source of my particular vibration.

It's of a lot faster rate / higher frequency than of a wheel revolving.

It's directly tied to engine rpms, no matter the gear or road speed.
Handlebars especially but also other parts of the bike that I touch
vibrate at such a rate that it feels like a buzz, which changes in
frequency and severity as the engine rpm varies. Objectionable
between about 3600 to 4300, less severe in 6th gear when the
engine is pulling a little harder than in 5th or the lower gears.

Just the nature of the beast (big horizontally opposed twin) as noted above,
can be reduced by good careful tuning but not eliminated. So playing
with gearing to get my rpms at the desired point (3k to 3.5k) at my
normal road speed as I noted, and will be added bar end weights.

Heard back from manic salamander that yes, indeed, their weights do
fit an r1150r with heated grips. Being the kit with one weight and
the cruise control aren't that much more, gonna spring for that
while I'm at it, then I have the cruise when I want it too.