Topic: HOW valve seats are cut

[lucky]

I have seen several posts where owners said the would just lapp the valves.
Here is a video that shows how they must be cut BEFORE lapping.
http://www.youtube.com/watch?feature=player_embedded&v=QIVj_L1akl4#!

The Honda factory tool did all three angles at one time with 1.5 turns of ONE tool.

The different valve angles are for the valve to contact with different harmonics at different rpm's.

[chewbacca5000]

Hi Lucky,

This is a great video that should come with the disclaimer, "I am a trained professional do not try this a home".  The neway system depends on two things to work properly super tight valves guides and an equally skilled operator.  Do not try this on the head you are about to bolt on there is a good chance things may not go the way you hoped for.

I took my head in to a local machinist and got my serdi cut and my valves touch ground and had a perfect seal after.  This after I had a good "Man Cry" at the tought of all my work and $ going down the tube.

The problem with the neway is it is almost impossible to make concentric cuts on the seat with even slightly worn guides.  Your guides must be perfect.  If you are interested in the cutters in the video I'll make you a heck of a deal!  Just send me a PM.

[Bob3050]

Lucky: Are you talking about the tool that Honda uses on the assembly line to initially cut the seats? All the shop tools that I have ever seen or used were three different cutters with three different  angles, 30 degrees, 45 degrees and 60 degrees. The 45 degree cut is the contact patch between valve and seat. The 30 and 60 degree cutters are used  to  position the 45 degree surface in the center of the of the valve and to narrow the 45 degree surface to no more than 1/3 of the valve face. This width and position is visible when the valve is lapped to the seat. This is the way I've done valve jobs on cars and bikes for many years.
Bob

[754]

 I dont think it has anything to do with Harmonics, just fine-tuning the flow by blending the area beside the actual contact seat. pretty sure Honda used single cut.
 Worn guide?, why would you try cutting the seat with a very , which could help..worn guide.. there is more than one size pilot

[chewbacca5000]

I dont think it has anything to do with Harmonics, just fine-tuning the flow by blending the area beside the actual contact seat. pretty sure Honda used single cut.
 Worn guide?, why would you try cutting the seat with a very , which could help..worn guide.. there is more than one size pilot

We'll I really didn't know any better to be honest.  Had Hondaman explain the guide thing to me after I could not get my valves to seal.  Now I know better. Nothing wrong with the neway system it's just not for me.  I lack the skill and experience to do it properly.  Now they will be going up on Ebay.

[Ernest T]

I like doing as much as I can on my bikes, but for $80 bucks I had a 400 head rebuilt.  They took it apart, measured everything, cut two valve seats, lapped two valves and air tested it after assembly.  Maybe when I retire I can get into that type of work.