There are certain things you can do yourself and there are certain things you should leave to the experts with the real tools. I’ve lapped valves before. It’s cool to play around with doing that for fun, but really… let the experts make sure your head is legit.
Mar automotive is an engine machine shop in Philadelphia. They specialize in cylinder head repair, and can do pretty much whatever you need done to your motor.
I’ve talked about Mar auto a handful of times on this site but I thought I’d give some more info.
I first learned about them 8 years ago when I was having an issue with my Honda S2000 car. A couple valves weren’t seating properly. Shit was all under warranty, I took it to the Honda dealer near airport, they took the head off and sent it to Mar. So I called Mar and asked questions about what was actually wrong with the s2000 head. They were friendly nice guys. So I said, hey, can I bring you a motorcycle head?
Since then I’ve had 3 or 4 heads done by them and other numerous friends have also brought heads to them. They always do a great job and are super quick turnaround. They’re a 15 min drive up frankford ave. They open at 7am ish so it’s easy to go during the week.
I disassembled my cb650 motor the other day to replace the head gasket. Figured I’d bring the head to Mar to freshen it up.
When I was there picking up the head they showed me around. Explained how some of their tools work, and let me snap some pics.
The below pics show the tool they use to shave the surface of your head or cylinders to make sure its completely flat. They can set it to remove a hair… or as much as you want to shave it.
The below pic shows the different angles to the valve seat and he explained how far in they can be.
Below pic is their valve cutting tool to get it perfect. They also measure all your valves to make sure they’re not bent. And what I mean by that is, they could be bent a hair, that you wouldn’t be able to tell, but really, that hair is causing them not to seat properly.
Below pic, he showed me when the seat is recut, and the valve is cut, they pop-push it in to see if the indentation line of where its seating is indeed in the correct spot on the valve.
Below pic. After they get all the valves done, they have a pressure-suction tool which actually measures if there’s even a microscopic leak. Next pic shows the gauge to check each chamber. When he was showing me this tool, I asked if flipping the head over and filling the chamber with oil was a good test, and he semi-laughed and said yes… but not really. A legit tool like what they have is the real way to know.
While I was there he told me a story about how a guy brought a 4cyl, 16 valve motorcycle head to Philly cycle center, and asked for a rebuild. Philly cycle center quoted him $750 ish. The guy said maybe, and then continued calling other shops. Mar talked to him and basically said, our price is $300 ish based on the hours it’ll take on the spec sheet for 4 cylinders and 16 valves. Why was Philly cycle center so much more? Who the hell knows. All Mar does, all day, everyday is build engines, and normally more complex car engines, so I’m pretty sure working on a little motorcycle engine is a piece of cake for them.
If you need to replace a head gasket, or if your bike is smoking or running like shit, do yourself a favor and don’t fuck around trying to replace valve seals and do a valve-job on your own, in your basement… have the head done by experts like Mar.
Years ago when I first got my Kaw z1, the bike actually ran pretty good. I took the head off and brought it to them to have it checked out, and they told me all the valve guides were super loose and all the exhaust valves were bent. Damn, I was shocked. Point being… your head probably is shitty and you don’t fully realize it.
Best logo ever.
Below pic, cb650 head finished. Valves done. Shaved flat. New valve seals. Everything checked out. Head was done in under a week.
Cylinders got a fresh hone job.