The Honda PCX / Forza / ADV150 / SH Forums

The vibrations of the bike at idle seem much quieter if I’m holding the rear brake.

When holding the bike with the front brake only, or not holding the brake at all, engine vibrations shake the bike substantially more than when the rear brake is engaged.

Not a big deal, but wondering if anyone else noticed, and if so, knew why.

Urbanian wrote: ... wondering if anyone else noticed ...

Sorry, I have a Thai bike and the idle stop really helps to get rid of the vibration.

I notice the same.

I added barend weights, all that did was make the weights rattle.


My best guess as to why the PCX vibrates at stop is because it's a single-piston bike. I've ridden some bigger single-piston bikes (usually call them thumpers), namely a Buell Blast, several KTMs, and a Harley once.. They all vibrate even worse than the PCX does. From my experience, some vtwins, all inline 4's, and all parallel twins are all much smoother because there's another piston offsetting the vibration of the first piston.

V-twin vibration is largely dependent on the included angle.
A ninety degree angle gives perfect primary balance and can be smooth as silk.
Anything else and it shakes like a prehistoric tractor engine.
Honda V4s, BMW boxer twins are also seriously smooth and the Z1300 six is like a gas turbine.

BMW use lanchester balancer to smooth the engine vibration. See http://www.ashonbikes.com/bmw_engine_balancer
I've see it on car engines before and it works great, but its another thing to time up when rebuilding one.

Alibally wrote:BMW use lanchester balancer to smooth the engine vibration. See http://www.ashonbikes.com/bmw_engine_balancer
I've see it on car engines before and it works great, but its another thing to time up when rebuilding one.

They don't use lanchester shafts

Technically not. The F800 instead uses a third ‘slave’ conrod to drive a bobweight, but the results are the same. It's based on a similar principle of counterbalancing any vibration.

Alibally wrote:Technically not. The F800 instead uses a third ‘slave’ conrod to drive a bobweight, but the results are the same. It's based on a similar principle of counterbalancing any vibration.

Not technically not, absolutely not. A lanchester balancer is a rotating balance shaft. Not in any way shape or form what the f800 uses.

Mind you I think BMW use balance shafts on the k series?

My shakes only when the brakes are held at the lights. When I've stopped and let go of the brakes, it idles very smoothly

SmellyTofu wrote:My shakes only when the brakes are held at the lights. When I've stopped and let go of the brakes, it idles very smoothly

I agree.

Mine idles very quietly, and the few vibrations I notice are located on the handlebars. If I hold the rear (or combined) brake, then the vibrations move to the seat, that is right to my back end.

I personally don't like it so I usually hold the front brake at traffic lights. But who knows, there's a chance that someone around here likes and actually enjoys that kind of vibrations in their "rear" .

Mine have the same symptoms. hen no brake is applied it will shake more than when the brake applied. But i only noticed it after reeding this post. i was never aware before of this issue.