1991 Hyundai Excel Won't start

1.5l engine, carburetor. It rarely starts until the car has sat for an hour or two. Usually starts fine when I top it up with fuel. Replaced the old 45 Ah battery with a new 55 Ah, but the problem is still there. It cranks but doesn't "fire". Idle rpm is around 1,200 when the car is hot, should be around 780 according to the service manual. Usually, when I start it there's a strong smell of gas. I don't have the usual air filter, I have a short ram K&N air filter.