900/1000 dogs compared to 650/750?

Ok went to get some parts and asked about the bikes in question. The 750 is a GPZ with an 810 kit. Ported heads, crane cams, dyna plate, header and 34 cv carbs. The guy lives above cleveland tennessee so goes to dragons tail in North Carolina about once a month to play. The 1000 has a set of denco pistons and is about 1175cc. Worked head, header, denco cams, air shifter, longer swing arm, drag bars. It was fuel injected at one point but has carbs now. They both still say that the plain bearing engines are cheaper to build and stronger than the roller bearing engines. Both say you NEED to weld the crank to safely increase the performance of all the roller motor engines and that is just wasted money on a street(track day every 3months) engine when you can spend the money on a plain bearing engine and make more power in a streetable package. Also the transmissions on the 900/1000s had transmission problems like 2nd gear, that the 650/750s did not.

I dont think you can really spin the plain valve engines any higher to make up for the smaller displacement. I think the engines will run into valve train characteristic speed limitations before piston speed.


The point they were getting at was not to cafe the 1000J I have in pieces, instead build the 650 with the 750 block I got from them and but an 810 kit in it. The bike will be much faster around the track than a 1000 on a dollar per dollar bases. Also it will be less likely to break.

Ok went to get some parts and asked about the bikes in question. The 750 is a GPZ with an 810 kit. Ported heads, crane cams, dyna plate, header and 34 cv carbs. The guy lives above cleveland tennessee so goes to dragons tail in North Carolina about once a month to play. The 1000 has a set of denco pistons and is about 1175cc. Worked head, header, denco cams, air shifter, longer swing arm, drag bars. It was fuel injected at one point but has carbs now. They both still say that the plain bearing engines are cheaper to build and stronger than the roller bearing engines. Both say you NEED to weld the crank to safely increase the performance of all the roller motor engines and that is just wasted money on a street(track day every 3months) engine when you can spend the money on a plain bearing engine and make more power in a streetable package. Also the transmissions on the 900/1000s had transmission problems like 2nd gear, that the 650/750s did not.

I dont think you can really spin the plain valve engines any higher to make up for the smaller displacement. I think the engines will run into valve train characteristic speed limitations before piston speed.


The point they were getting at was not to cafe the 1000J I have in pieces, instead build the 650 with the 750 block I got from them and but an 810 kit in it. The bike will be much faster around the track than a 1000 on a dollar per dollar bases. Also it will be less likely to break.