Engine reassembled, have a concern

F

frederick

New Member
Hey guys, hoping you can help me out with a concern of mine. Last weekend I got my cylinder head and cylinder back from the machinist. The cylinders were bored and honed, so I bought new pistons and rings. I had the head ported and had some valve work done, my valves were pretty trashed looking. I also had the head decked in hopes of getting some extra compression. (This is what's worrying me right now) Anyways, after I got the engine back together I've come across something that is making me a little nervous. When rotating the engine right before I get to top dead center and fire the engine becomes very hard to turn. This is with no spark plugs in.

I've pulled the cylinder head off the engine and had someone hold down the cylinders while I turned it and verified that the problem did not lie in that area. While I had the cylinder head off, I checked the tops of the pistons and I could not find any visual evidence that the tops of the pistons had made contact with the cylinder head.

Is it normal for this to happen or do you guys think I'm in trouble.

Thanks in advance.
 
If you remove the rocker cover, does the problem persist?

You could be facing one of two things... first, your pistons are contacting the valves. This is very bad if you've tried to force things, you've probably already bent a valve. The clearances on a built motor need to be checked with plasticine clay (see my 360 build thread for details).

The second option is that you're just facing resistance from the valves springs and this is fairly normal, though it shouldn't be too bad. A few pounds of force on a 14mm wrench on the end of the crank should be enough to overcome this, but it will definitely be noticeable. Removing the rocker cover will result in this resistance going away.
 
Thanks for the reply. I actually broke a head bolt yesterday putting the thing together. I swear, this bike will probably kill when/if it ever gets done. So I couldn't check it without the rocker covers back on. But when I went to see if the valves were bent, which they all look to be seated properly, I found that pistons had been hitting the head. Lucky me, right?

Here's some pictures of the damage. Which I don't think is a lot to worry about. I'm going to have to get a hold of the machinist who did the work and see what can be done. I'm thinking the areas where the pistons have made contact can just get ground down? Or the other route I'm thinking is running a double head gasket. I'm hoping the former turns out to be the better option, at least then decking the motor wouldn't have been a complete wast and I should still be able to bump up the compression a little.





 
You can't double up on gaskets. It doesn't work.

Before making any changes, verify the contact points and locate the locations where clearances are an issue. Then you can decide what to do about the problem.
 
mydlyfkryzis said:
You can get a copper head gasket that is thicker also...
Click to expand...

That would be my advice. Go a bit thicker on the head and keep the deck height closer to zero.

But yeah... check clearances first. Just don't go replacing parts until you know what you're facing.
 
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