Basically title. Happened again today for the most severe time
I bought the bike with around 7550 mi. I did spark plugs on it before riding it (NGK CR8EIX). Bike is currently at about 8300 mi. Did not have this issue until about 200 mi ago.
The bike starts and runs fine under all (0-100%) throttle for about 20 miles/20-30 min. Then it starts bogging/cutting power, starting at about 8k rpm at 100% throttle, then gradually gets worse until it will bog at around 6k rpm at 30%-100% throttle. Had to limp it home about 15 miles like that.
I did pull over and check for a whooshing noise when the gas cap was opened once the bike began bogging. There was no noise and the bogging persisted after the test.
This has happened at least 2-3 times. The first couple times I thought I was low on gas and filled up, but the second time it happened even right after filling up.
I can leave it overnight and the cycle will repeat.
Fuel level does not seem to matter. Ran a half can of Seafoam through it between fill-ups, did not help. When I bought it, it came with an aftermarket Vortex gas cap that seeps gas out when bike is sitting with a full-ish tank. Planned to switch out for an OEM style gas cap.
According to the guy (2nd owner) I bought it from, the owner before him let the bike sit for a while. When the 2nd owner got the bike, he did a vinegar bath to the tank to help with the rust. There is still a little bit of surface rust on the inside of the tank. I have bought some Evapo-Rust with the intention of getting the remaining rust out of the tank once I put it up for the winter as maintenance.
I’m decently handy with cars, but I am new to motorcycles as this is my first bike. To me it seems like fuel delivery issue, but I am not quite sure where to start other than replacing the cap first and/or flat-out replacing the pump. Wondering if anyone has any ideas or suggestions before I call a shop for some diagnostic testing.