I'm in the process of rebuilding my 350x. I bought it not long ago but was unable to really test ride it becuase of a ruptured disc in my neck. My neck has since healed & I have found some problems. When I got it home it was a pain to start, as in 25+ kicks , if it started at all. The guy I bought it from kept it in a warm garage & it started on 2nd kick. When started it runs very strong but I did notice the crankcase was low on oil after several hours of riding. I topped it off with conventional oil & it smoked really bad when cold. I tore it apart to find what appears to be a 12:1 wiseco .5mm over. The cylinder was real smooth but tpaer was minimal so I honed it. The valves werent white so it did not appear to be running lean. The local honda dealer tells me the head needs new seats & guides wich they can do for about $100 & that the valves are re-useable. Since IN have the head off of the machine & since you can never have enough power, I was wanting to port the head.So, does anyone have any tips on porting? Also, does anyone have any tips for the rebuild, expereinced any problems with seats & valves or have anything to offer?
I am also putting in a EBC clutch & will be looking into the lack of dampning of the front forks soon.

Jim

 

When porting your heads be conservative. Concentrate on smoothing any casting flaws and removing extra material immediately behind the valve. This is called pocket porting. Also, you can free up a little power by port-matching the intake and the exhaust to the head. Beware, don’t just "hog" out the ports, this will take out velocity and you will loose torque. Concentrate on the shape of the ports more than the size. Unless you don't mind running 110 octane I wouldn't put a 12:1 CR piston in it. Unless you have a cam with a lot of overlap to bleed off some cylinder pressure, a compression ratio of 12:1 will create a violent "ping" and you will trash the rod bearings or you could even break your piston. The only problems I have seen with the valve train, is Honda uses valve springs that are ultra stiff and they tend to wear the camshaft lobes down. So check your cam closely for wear, if it’s worn...replace it and the rockers! If you don't replace your rockers with a new cam, they will wipe the lobes off your new cam in no time! Good luck!

 

As for pining, I havent heard any & have been running 87 octane in it. I am thiking the carb has been rejetted. The fact that its winter time here in NY & its cold may also be keeping temperatures low enough to prvent ping, I guess I'll find out this summer. If it is pinging due to too much compression I'll probably pull it apart again & just mill the piston dome down. Again, I am not sure its a 12:1 but with that big of a dome it just has to be. I have no idea on the cam specs & havcent looked at it that closely. If it is an aftermarket cam do they usually have their name or some other featured stamped into the cam somewhere?

Jim

 

When I had my 250R, I had my @ss handed to me, really bad, by a 350x going up Oldsmobile Hill at Glamis. I talked to the guy who said it had a Curtis Sparks 480 kit with ported head, big carb, the whole works. I watched that guy kill everything that ran against him, very impressive.