5 angle valve job

[Chanman420q]

hey i had my quad in for some repairs and my mechanic gave me a 5 angle valve job. what exactly does it do? from my understanding it makes less friction in the head so air can flow easier. and it comes with a 3angle strait from the factory. he didnt charge me anything, but im just wondering what the deal is with them

[nakomis0]

"from my understanding it makes less friction in the head so air can flow easier. "

Yup thats my understanding too.

[Wayne64SS]

its going to seal that valve better when it closes because it has essentially 5 different places to create a seal instead of 3! They are easy to do i did them when i was in school for automotive repair!

[MIKE400EX]

The valve only seals against one of the angles on the valve seat (and the corresponding one on the valve), not all 5 at the same time. The incoming air has to flow between the valve seat and past the valve circumference to get into the cylinder. The more angles cut/ground on the seat (and valve face) the closer those areas approach a smooth curve or radius. In theory the smoother contour flows better then a more acutely angled one. There is some trade off: The area(s) that the angles are cut on is fixed, so the more angles that are cut, generally means the narrower each one will become. The narrower the contact area is (again only one angle makes the seal) the quicker it will wear since the per unit loading is higher. Also a narrower contact face yields less heat transfer area from the valve to the valve seat. It's a trade off between flow and longevity. A three angle valve job will generally last longer while only sacrificing a small amount of flow potential. It is possible to do a "radiused" valve job, They usually don't last long and are a REAL pita to do correctly. You really need to flow the head with each type of valve job type to determine which is best for the application.
There.....I just saved Wilkin some typing!;)

[Kilabanshee]

Yeah listen to mike400 he knows his stuff.

[Chanman420q]

so.... does this mean more power? as in what asspect, HP all together? tourge? throttle responce? i might as well understand what he did to my valves

[MIKE400EX]

Chanman,
If it is indeed a 5 angle valve job then the head should flow ever so slightly more than a 3 angle one would. It would be very hard to measure that sort of improvement alone, especially on a 40HP motor - maybe in the tenths of a HP if both are done right. Any gains would be across the board, but more noticeable during higher flow conditions.

Just so you know, the 3, 5 or however many angle valve job refers to the number of angles cut on the valve seat. NOT the total number cut on both the seat and the valve. I've come across a few shops that try to sell a three angle valve job as a more costly (re. more labor intensive) 5 angle one, because they were also counting the two that they cut on the valve. Anything to sound better and charge more for.

[Chanman420q]

Originally posted by MIKE400EX
Chanman,
If it is indeed a 5 angle valve job then the head should flow ever so slightly more than a 3 angle one would. It would be very hard to measure that sort of improvement alone, especially on a 40HP motor - maybe in the tenths of a HP if both are done right. Any gains would be across the board, but more noticeable during higher flow conditions.

Just so you know, the 3, 5 or however many angle valve job refers to the number of angles cut on the valve seat. NOT the total number cut on both the seat and the valve. I've come across a few shops that try to sell a three angle valve job as a more costly (re. more labor intensive) 5 angle one, because they were also counting the two that they cut on the valve. Anything to sound better and charge more for.

im not being charged for this, and if i am im going to flip, because he just called me and said, oh ya we did a 5 angle valve job on it while we were in there

[MIKE400EX]

Chan,
It's OK if he did a real 5 angle job. He shouldn't charge that much more for it, not like 2x or 3x as much. After all it's (unfortunately) only a one cylinder engine with 4 valves

[Kilabanshee]

Hey Mike what you doing next week want to go up to freeland?

[MIKE400EX]

Brent,
I'll check it out and call you.

[Kilabanshee]

Yeah iam heading out to maryland this weekend for a few days but then ill be home. Give me a call today "Thursday" or Friday.