rm 250 problems

[scottc1088]

just bought a 1984 rm250
anyway it starts up but when you rev it, it doesnt get into the powerband it just splutters, also when you let off throttle it seems to take a long time for the revs to go back down and the throttle isnt sticking
i tried again, it wouldnt start so i bumped it and it started, when you try to rev it like just before it goes into the powerband it splutters and theres flames coming out of the exhaust and carb
the compression isnt that great so could this cause that problem?
it doesnt have powervalves so that cant be the problem

the exhaust seems to get very hot aswell
i dont know what else to check, there doesnt seem to be any air leaks either
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2000 Derbi Senda R, Malossi 80cc, evolution n.g. full circle race crankshaft,26mm carb,Malossi mhr exhaust,TNT filter,Hebo reedblock + carbon reeds,Alien front light,Kundo 330mm rear shock,13-53
Breaking 2000 senda r