What is this noise

[Bugs In My teeth]

I have a 02 VLX 5600ml. I have noticed that when I ride 2 up, and start to go up a grade, the engine sound changes , Not just a lugging sound but almost a poping noise..
Normal is a steady thruom... but accelerating up the hills I get a Pap, Pap, until I eiher power throught it or down shift.
Not sure if if is coming from 1 or both pipes.
this is something new, did not make this noise until resently.
Could it be valves... Plugs..Adjusted valves myself @ 3200.

[O'Larry]

Sounds like you are maybe lugging the engine down too much. Downshift and it should be better.
O'Larry

[Bugs In My teeth]

Wish it had a tack. I can have know idea how fast I can go in 3rd before I need to shift, I hear the VLX has a wide shift range, but how wide.. Don't want to blow it up.

[mikemilburn]

Ad O'Larry said, it sounds like you're lugging it.
Could be pinging, pre-ignition, spark knock it's the same thing just different names. Usually it sounds like a bunch of marbles banging around inside the engine tho. If it is, it's not good for an engine at all.
It's caused when the gas ignites before it's supposed to as the piston is still on it's compression stroke so you can imagine the stress on the engine....Mike

[Cbjr]

Originally Posted by Bugs In My teeth

Wish it had a tack. I can have know idea how fast I can go in 3rd before I need to shift, I hear the VLX has a wide shift range, but how wide.. Don't want to blow it up.

The bike is equipped with a Rev-Limiter - no fear of blowing it up - let the beast loose.