1979 yz250 help

Yeah, my family recently bought 3 acres out in the country, and in one of the buildings was several OLD dirtbikes, including this 1979 yz250(not completely sure thats what it is). It seems to run pretty good, it was used for competitive racing back in the early 80's, and then after 1 season it sat until this year. After a quick carb cleanup it does run, and it goes pretty damn fast for it being so old. however, there are a few problems I'm having. First, the stock pipe was rusted out at the bottom. it is very loud right now, even after a quick fix(peach can sliced down the side and 2 hose clamps:)). However, it doesn't have very good lowend power. On a gravel road starting from idle I can run it all the way through 1st, 2nd and 3rd and get no roost anywhere. It does have IMMENSE rear tires which may be part of the problem, but then again it doesn't wheelie either unless I rev it all the way up when stopped and drop the clutch, then it goes straight up. I'm thinking that:
a. I need to clean the carb and
b. change the timing

the spark plug doesn't foul, and it stays pretty clean.
also, there is 1 hose coming from near the carb that just ends right above the shifter, and if you tip the bike to either side it leaks gas from there. I would also like to know how it is cooled. Unfortunately it won't let me put a picture on here which is totally gay.

also, I uploaded a pic to the site so if you do a search for vyamaha yz250 it should come up. and one thing i didn;t mention is that it takes up to 30 kicks to get it to start if it's been sitting for over a week. however if i run it for say 20 minutes, put it away for 3 hours I can come back and start it first or second kick if the engine is still somewhat warm