[proxr441]

i have a friend that has some machining tools so i was wondering if anyone would have any spec's that they can throw at me so that i have a few extra hps at 8250-8600 rpm

 

[W.F.O.]

since you have a prox440 as well, why dont you pull the head off of it and measure the 440 port heights and copy them in the 500 cylinders.
you will then need to shorten your pipe a bit (1" = about 250rpms)to rev the extra couple rpms where the 440 porting likes to run.

 

[alsled]

Its a 500 ride it for what it is. Its a good motor but I don't think theres to many people modding it. Even a full trail porting would probably give it 4 at most.

If you want clean the ports up, DO not start changing port heights or you might make 2 flower pots out of the jugs.
Do not polish intake port, leave rough.

Match the y-pipe to the ports and go riding.

 

[madcow]

all the port work in the world wont get you to 8600 without a pipe to match. a good port job is worth 5-8 hp. depending on your sled. but you will noticed a quicker throttle response and cleaner running. but it will still run the rpms your stock motor is suppose to run.
before you just cut an inch off your pipe and expect big things. you have to remove a little from the head pipe and a little from the chamber. how much depends on your pipe.