My quad is down for a new top-end and I thought to myself, why not get it ported while the motor is apart. A friend of a friend says he has ported 250R motors before and had a pro teach him how to do it and explained to me how he does it. I asked a pro in town who has done porting for 13 years and he explained how he ports motors. What he said was exactly what my buddy said except the pro guy used different measurements. His porting is very expensive and I was wondering if I should let my buddy go at it.

PLEASE, any EXPERIENCED port guys: If my buddy knows what he is doing but doesn't use the same measurements as the pro dude here in town can he mess up my motor?
ALSO: About how much hp will porting provide?
How much hp will just cleaning up the ports provide?

 

Measurements ALWAYS matter! Being in the muscle car scene you hear a lot of guys say “Ahh just grind out some metal here and there” Well, that has got to be the absolute worst thing to do! Sure you may get away with it once in a while, but not always. The whole purpose of porting or polishing cylinder heads is to reduce turbulence and increase flow and fuel/air capacity. I wouldn’t let anyone work on my stuff without a blow bench and plenty of experience! This way you can see the results on paper. If you just blindly remove material from a head you can actually increase the turbulence or create a pocket where fuel/air wind up trapped.

Please please please please please don’t listen to just one person when it comes to engine machining. Ask around, look up places on the internet, find people that will give you testimonials. I made a HUGE mistake the first time I built an engine for my ’69 Mustang by letting some Joe Schmo grind away at stuff. I regret it 100% now. To say the least, I ended up building an entire new engine about one year later! What a waste of money!

Sometimes the best people aren’t always local. Talk with my friend Jeremy @ www.rageperformance.com He’s a very cool guy, ex-pro racer, very professional, very nice, and very knowledgeable. His company does a lot of engine/port work. He’ll be more than happy to help! It’s been a while since I’ve talked with him, but tell him Jason with the Tecate from Michigan told you to call. I’ve talked to him several times about big bore kits for my Tecate.

Hope this helps.

 

As little as .001 of an inch can shift your power 500rpm's! The purpose of porting in most casses is to bias the engine for a specific rpm range. Unless he knows how to degree a port and set up durations for the inteneded power band I wouldnt even consider it. On the other hand just cleaning up the ports cna be very easy as long as he doesnt get carried away. I really wouldnt let anyone I wasnt completely trustworthy in raise my ports, change the angles on my ports, or widen my ports. It is a very EXACT science.