this seems to be the most knowledgible forum on here and i was wondering if any one could give me some links to learn how porting is done. basically the do's and dont's. thanks

 

DO get it done by some one other than yourself

DON'T do it yourself

Any questions?

-nick

 

anyone else?

 

It is hard to answer a question like that. It depends on a lot of things, what cam are you using, what kind of performance are you looking for.

All I can tell you is that bigger is not always better when it comes to porting, and leave the combustion chamber alone..

Hope this helps!!!![img]i/expressions/face-icon-small-smile.gif[/img]

 

it all depends on what your porting, and why type of riding you do

 

the straighter you can make the path for the air to flow the better the performance will be. on most heads you will have to trim the short turns to accomplish this. On the Raptor the valves do need to unshrouded, which means opening up the cumbustion chamber. If you use a 12-1 piston you will still have plenty of compression (over 11-1) and less chance of detination when using fuels like Ulimate 4 which only has 92 octane but lots oxygen to increase performance. Remember, the raptor has a 4" bore which is equivilant to 1 piston in a small block chevy. To get 100 hp per cylinder it takes .800"valve lift from a cam. we will never get that in a raptor cam nor will we ever get the flow out if a "yamaha" raptor head to do so.

 

As was said, bigger is not always better. Take for instance Big Block ford heads. The best improvement on those is to put in a port plate. A port plate is a piece of steel that goes in the exhaust side on the bottom of the opening. It cuts the size of the port in half, but makes more flow! Also with bigger intake ports, you loose air velocity which causes lots of problems.

A friend and I built a 400 (.040 over so it is actually 408) that turned 815hp on race gas and it only had just over .700 lift solid roller. Made that little Chevy II run.

 

where can i learn what size ports suite the mods and riding styles? thank yall for the replies.

 

Which ATV????

 

im not just curious about one quad. i want to know about it in general, concerning 2 and 4 stroke engines. if you can give me info on just one quad i would aprreciate that as well. thanks im sorry im not making this easy