Drastic loss of power!

I lost a lot of horsepower all of the sudden out of nowhere! I didn't ride for a few days and when I got back on I was practically out of gas so I went and filled up. I usually use 93 octane but someone told me that the first gallon you get is of the quality that the guy before you uses because of the gas stuck in the hose and nozzle so I decided that I would use just 90 octane. I don't think that is the cause, but would that make you lose a lot of power?

Here's the situation: I used to be in second going like ten and rip on the throttle and be doin 50 before I could blink or be on the highway and drop it into fifth and pass right by people and it just doesn't take off like it was a few days ago. I also noticed that right after I filled up, if I held it at 4 or 5 grand the exhaust would make almost a backfiring noise but softer and continuously like pop....pop.....pop....POP....puff pop but it has stopped doing that now.

So whataya think? (Could an oil leak cause loss of power? no right?)

 

maybe you got some gunk from the bottom of the tank in the bowls. do you have a fuel filter?

 

Crap in the Fuel Bowls.
Fuel Starvation.
You might have to clean the Fuel Delivery System from the Petcock Screen to the Carbs to get the Full Power back.

 

Check for a bad plug it may only crap out at higher rpms.....

 

Will check plugs. Bike only sat for three days but it was the emptiest I've been so I suppose it could be gunked. I also noticed that I am leaking oil from my head gasket in the front of cyl 1 and 2. Think there's any way that had something to do with it?

 

if you are losing compression from that gasket, yeah... but I wouldnt put it on that as being the cause.
also, double check your fork seals. if one is leaking and spraying the engine with it, it will appear as a head gasket.

 

Your oil leak is most likely valve cover or cam chain tensioner gasket; the oil runs around to the front and makes you think bad things...

It sounds to me like you polluted your carbs and/or fuel system.

 

Can I run seafoam through it and expect any results or am I going to have to remove the carbs again and clean them? And could you tell me more about the other gaskets you mentioned? B/c looking over it, from the front of the bike, there is oil where the head gasket is but only below it (none above it) on cyl 1 and 2. And looking from the side there is a little build up on the walls by the plugs, as if it was spraying up from the very center of the block where there is the 'bridge' for the chain that separates the plugs.

 

seafoam will break down varnish, but not rust or dirt.
I would pull them, personally

 

A picture of the oil leak with the oil highlighted would be useful. I've had a leaking cam chain tensioner gasket that was somehow managing to leak out around the front of the #1 and #2 cylinders. I would say that if it is just a slow leak that chances are it is not the source of your problems. Also +1 on the value of an inline filter but make sure you get one that fix well to the bike and doesn't restrict the flow as I was having a simuliar lack of power as you (just not as bad). About 3 weeks ago and I simply removed the inline filter during a test and the bike started to run good agian.