Heavy engine vibration

[535is]

I've recently noticed I am getting a heavy engine vibration, especially under load (accelerating, going uphill, etc.). It occurs even on flat roads beginning at about 3750 rpm and continuing on up. It almost feels like, but doesn't seem to be, a miss because I don't feel a power loss and it sounds fine. I believe it isn't driveline related because it occurs in each gear at the same engine speeds.

It originally started after I'd ridden the bike continuously at speed (~60 mph & up) for about 20 minutes. It doesn't seem to hurt anything - yet. I rode it for two 90-minute periods yesterday on a round trip and it seems not to be getting worse, but now doesn't seem to want to go away. It was happening on a short 4-mile ride this afternoon. I am flummoxed. Ideas? Otherwise, I'm starting by pulling the plugs to take a look-see.

[PGlaves]

I've recently noticed I am getting a heavy engine vibration, especially under load (accelerating, going uphill, etc.). It occurs even on flat roads beginning at about 3750 rpm and continuing on up. It almost feels like, but doesn't seem to be, a miss because I don't feel a power loss and it sounds fine. I believe it isn't driveline related because it occurs in each gear at the same engine speeds.

It originally started after I'd ridden the bike continuously at speed (~60 mph & up) for about 20 minutes. It doesn't seem to hurt anything - yet. I rode it for two 90-minute periods yesterday on a round trip and it seems not to be getting worse, but now doesn't seem to want to go away. It was happening on a short 4-mile ride this afternoon. I am flummoxed. Ideas? Otherwise, I'm starting by pulling the plugs to take a look-see.

Check the syncronization of the carbs. It sounds like a combustion imbalance to me.

[535is]

Thanks. Will do.

[DennisDarrow]

Welcome back PAUL.............so very good to see you here again.............Glad you are blessed and still with us...........Dennis

[PGlaves]

Welcome back PAUL.............so very good to see you here again.............Glad you are blessed and still with us...........Dennis

We've been on the road for three months, with occasional but not regular good internet access. I have high speed now for a little while. But back on the road soon. I try to keep up with this Forum, but don't always have a decent enough connection to write much.

[tghsmith]

Iwould check for a holed diaphram, timing closed up and advanced to far, then the valve condition.

[AnnapolisAirhead]

Sounds like carbs out of synch at the throttle cable barrels that screw into the carb top. If you twist the throttle and the engine stumbles a bit, one carb if mixing before the other. Could be other things, but I just had that problem and the cable adjustment did the trick.

Does it only happen at speed and not taking off from a cold stop?

[nealart]

Check carb balance.

Check Timing.

Check fuel delivery.

[vanzen]

"don't feel a power loss and it sounds fine"
"beginning at about 3750 rpm and continuing on up"
"...it seems not to be getting worse, but now doesn't seem to want to go away..."

carb synch will do that – cables not pulling the plates equally,
but I'm stumped by the "don't feel a power loss and it sounds fine"

IMO. the description sounds as if "something is coming loose",
so I'd also be checking engine mounting bolts, axle nuts, pinch bolts, SA, and etc. for proper torque.
and the 4 bolts that hold the driveshaft / trans output ...

[535is]

"don't feel a power loss and it sounds fine"
"beginning at about 3750 rpm and continuing on up"
"...it seems not to be getting worse, but now doesn't seem to want to go away..."

carb synch will do that – cables not pulling the plates equally,
but I'm stumped by the "don't feel a power loss and it sounds fine"

IMO. the description sounds as if "something is coming loose",
so I'd also be checking engine mounting bolts, axle nuts, pinch bolts, SA, and etc. for proper torque.
and the 4 bolts that hold the driveshaft / trans output ...
That last possibility (something might break) is lurking in the back of my mind, so I was not really pushing it past 3/4 throttle. By 'no power loss' I meant it is definitely running on two cylinders and not just one.

'Sounds fine' is part of a new experience for me. This has been a very noisy bike to ride,, for me and I have finally discovered what it is, more precisely, that makes it so. It is my face position behind the windscreen. It is just where the wind makes the most noise around my face shield. I can duck down (but not be able to see) and it's quieter and I found out by standing on the pegs (for the first time) at speed, it is quiet then, too. Just a nice smooth rumble. My helmet is normally at the worst possible place for wind noise. So I normally wear earplugs on longer rides.

If something were loose, I don't think it would be more vibration-prone at midrange than it would be at low rpm. This really comes on when I crack the throttle open, but it runs fairly smooth at steady state speeds.

Carb synchronization seems to be the first place I want to look.

[tghsmith]

being 6'2" and riding a rs I have the slightly taller windshield( Does not look out of place on the bike as some of the very tall do) years ago I made a small deflector mounted to the top lip, roughly a 5 x 5 piece of plexy 1inch on a side is bent over a little less the 90degrees(lay the plex on flat heat resitant surface with the one inch or so hanging out and heat with a heat gun or propane torch slowly untill the edge starts to droop) its mounted to the top lip with 2 holes and plastic hardware, clamp it in place and drill the WS and the deflector at the same time. helmet noise is gone plus it stops most of the bugs. once it it stopped a kamakazi starling.

[nealart]

Would you be able to post a photo of the windscreen?

[tghsmith]

http://klasjm.smugmug.com/gallery/3127832#176316378_Uat8a
dont know if this link will work, if it does its a side view but gives you an idea of the concept

[nealart]

Thanks. What a fantastic bike!

What brand of windshield is it?

[tghsmith]

have to stop hijacking this thread, WS is now sold through gustefen(spelling not correct)

[vanzen]

have to stop hijacking this thread, WS is now sold through gustefen(spelling not correct)

link:GUSTAFSSON PLASTICS (http://www.bikescreen.com/)