Topic: need my head straightened out

[Elan]

Ok so I have a hodgepodge engine in my 76 750k and its been performing, but I think its performance could improve.

So The crankcase is a 72k, cylinders are mid 70's K with an 836bore (k pistons), and then theres the head...78f!

Flat pistons with a head thats shaped for domed pistons= loss of compression, right?.  Not to mention the oil drains are different, etc, etc,  Its running good, but I think I need to address it.

I found all this out when I was reassembling after boring out the cylinders.

So what are my options under $500 bucks? I guess the obvious one is get a used k head, but what year would you recommend? or a larger bore with F pistons? I lean toward rebuilding an old K head since my 836 is only 200 miles old. I would probably do it myself if I went that route.  But then would I need to get new exhaust to fit?

Or pretend it never happend and keep riding... Not really sure how much I'm losing with my setup.

Any ideas?

[Rigid]

If the power works for you, ride it until something comes up that requires removing the head.  I would get a good used K head and go through it completely with a seat cut, lapping, new guides and seals if needed.  A quality gasket set and you are good for decades of riding.

[KJ790]

If you have got the oil port situation sorted out then you can get away with the F head. Which K pistons are you using? Is your head an F1 or an F2/3? You can measure your valve-piston clearance and see how much can be shaved off of your head to get the compression ratio up. I am running an F3 head with 836 flat top K pistons. I was able to shave off .060" off the head to get the compression ratio up to 10:1 and still had sufficient valve-piston clearance. I know that the F1 combustion chambers were not as deep as the F2/F3, so you wouldn't have to take off that much to get the compression up.

[Elan]

yeah the oil situation is at bay, but not sorted out. I fear water may get in through the exposed rods.

I have flat k pistons with the f3 head also. I didnt even think about shaving the head. I did just buy a 77k head on an impulse haha. Can I just transfer over the f3 cam and towers?

[cbr954]

If you have the head milled that much then you need to start looking at how far off the cam timing will be.  Its not an issue if you have an adjustable cam sprocket so you can degree the cam back in.