he must have tzr 125 ive derestricted myn i did it by cutting the restrictor out of the exaust, putting a 13 tooth frount sprocket on as it over revs horrably with its standerd 11 tooth.also i have up jetted it to a 95 main jet. i think there is somthing els in the engine manifold because theyve put some funny bolts on thered so u cant get in. althought as myn is it can hit 60 when i get my head down not bad 4 a 50! if any 1 knows of ne other restrictions plz let me know