I am kinda taken aback that I found an old unused plastic (?) toolbox that had compartments to separate the valves and parts. I marked them and plan to package the stuff and ship it out to Ben..... ehhhh... maybe today. LOL I machined .010" off my heads. Reasoning? I have a lathe, I made a plate years ago so I could bolt the heads to it. I figured I'd use it and I was kinda bored. I gotta have a look at this thread to figure out how much squish you guys are giving. My first engine I went to .005" (top of piston to cylinder deck). Seems that knowledgeable people recommend .038" (head gasket thickness included). As mentioned previously there is a .005" difference in the deck height as the motor sits right now. The SV is just hella fun to ride.
Are the SV650 valves stellite or titanium? I ask these questions because I'm trying to determine what the accuracy of the valve to seat is. If a seat is lapped with one valve and another valve is placed there how accurate are the mating surfaces? How concentric are the seats compared to the surface of the new valve?
Def not Titanium SV 650 In 12911-46E00 36.78 Ex 12912-20F00 47.53 Gsxr Def Ti In 12911-37H00 107.00 Ex 12912-37H00 97.48
Valves are steel. Very few valves are lapped anymore. The valve surface mate and seal when being slammed into the seat at 10000 RPM very well. On new parts with a quality valve job and accurate angles, lapping a valve under hand applied pressure does a lot less than a lot of people think.
Depends on who is doing the valve job. All of that can be determined with things like prussian blue and a leak test.
As a machinist by trade and repairer of all things mechanical... like most lawyers are apt to do in a trial, I can find someone to tell me whatever I want. That doesn't mean it is entirely wrong, but that... there are different opinions. Lots of mechanics still lap valves, especially the ones that don't want you to spend a lot of money. I long time racer and shop owner recently told me to just lap the valves and put the engine back together. That will work, but I wanted someone to look at the head and the valves that has a lot of experience with these engines on the racetrack. Even in machine shops 40 years ago, when we worked on VALVES (water, steam, etc...) some shops machined both surfaces and just barely lapped the valves, some never machined surface unless they were really bad which was often the case. It is as clear as mud. LOL Good luck.
Ok, thanks guys. The reason I'm interested in this subject is because on the Chevy engines that I've been involved in building, after doing the necessary port work, we get the valve seats to within .0003 of concentric, get the valves to within about the same, then hand lap the valves until they will hold a vacuum when applied to the port. I just wanted to know if these SV engines are built to about the same specs also.
LOL, I get amused when I hear, or read, some article where some guy is talking about doing a "three angle competition valve job" on his heads. Hell, I was doing that many angles in the fifties and sixties on valve jobs for tractors. Many mechanics don't understand the practice of doing however many angles it takes to get the air flow as good as it can be. In fact, a friend of mine, that has been building competition Chevy engines ever since the first small block engine came out in 1955, has done as many as eight angles in some heads. You're right. A simple lap job on a valve and seat is ok for a single quick repair until you can take the heads off and do a solid professional valve job, but it's not what needs to be done for best performance. If a valve needs lapping then it's entirely possible that there are other factions of the system that often need attention also. Installed height and installed seat pressure of the spring, valve guide wear tolerances, valve stem wear,,,,,,,,,the list goes on and on. If any repair is worth doing, it's worth doing as absolutely best as can be done. All those tiny little details are what gives one guy the ability to pull past another rider down the straight. It all makes a difference. :up:
Ovis sounds like we are from the same era in time as well as neighboring states. LOL You musta built some haul azz tractors back then. LOL You are correct, I want someone to look at all those parts you mention. I agree that the valve seat is only part of the story, lots of other stuff that wiggles and wears in there and sometimes they break apart. I'd like to avoid that. With regard to being neighbors... I might have to move over that way if it goes bad. LOL
With most auto heads 5 or 6 angles is fairly normal but when you can create the correct flow characteristics with different numbers then that's what you do.
