no compression on revalved head?

I put all new valves in my 1977's head, reassembled the motor but I'm getting no compression. The gasket is new. The valves I used were for a 1976 (square keepers) but it was my understanding that the valves themselves were compatible so long as you used the right keepers (which I did -- i ordered the square ones). Once I determined that there was no compression, I called it a day. Any ideas about what my next step should be? I'm a novice. Thanks.

You say you put some valves in. Please expend on that a bit, did you use new valves, or grind the old ones you had? Did you check the guides, and cut the valve seat angles? Did you check for install height? Check the valve clearance to camshaft? Etc.

Motor Head wrote: You say you put some valves in. Please expend on that a bit, did you use new valves, or grind the old ones you had? Did you check the guides, and cut the valve seat angles? Did you check for install height? Check the valve clearance to camshaft? Etc.

All new valves (but spec for a 1976 not a 1977). I did not check the guides or cut the valve seat angle. I also did not check for install height as I believed these would be OEM spec. I did not check for clearance. Just put them in and put it back together. Being honest here. I need advice. Thanks.

You will be pulling the head back off I would for sure. These things need to be done correctly for it to work, let alone last.
Do you have a manual for your bike, as it is necessary for the specs and procedures. Best to leave such work to a qualified machine shop.
you can take off the valve cover and check the valve clearances, you will find that they are tight, probably. Adjusting them may gain some compression.

Motor Head wrote: You will be pulling the head back off I would for sure. These things need to be done correctly for it to work, let alone last.
Do you have a manual for your bike, as it is necessary for the specs and procedures. Best to leave such work to a qualified machine shop.
you can take off the valve cover and check the valve clearances, you will find that they are tight, probably. Adjusting them may gain some compression.

Ok. i'll pull the cover off tomorrow and check the clearances. I do have a manuel. Thanks.

I would check the clearances first, before pulling head, if that checks out, take head off and set it on its side, pour gas or diesel down in each port, check to see if the valves are leaking, do the same for exaust. If they are leaking most likely you will either need to lap them back in or have a machine shop do a valve job.

Hey rich, did you lap the valves? Also with mentioning, money spent with Larry c. Is money well spent, he's right down in morgantown

The valve seats and differant valves need to be machined together to get a good seal

Hoping the cams and cam chain were correctly installed.

Good Fortune!

Before you put it back on the next time, vacuum test it. Most top head shops have a vacuum tester.

richrand wrote:

Motor Head wrote: You say you put some valves in. Please expend on that a bit, did you use new valves, or grind the old ones you had? Did you check the guides, and cut the valve seat angles? Did you check for install height? Check the valve clearance to camshaft? Etc.

All new valves (but spec for a 1976 not a 1977). I did not check the guides or cut the valve seat angle. I also did not check for install height as I believed these would be OEM spec. I did not check for clearance. Just put them in and put it back together. Being honest here. I need advice. Thanks.

I'd start there.

APE Jay wrote: Before you put it back on the next time, vacuum test it. Most top head shops have a vacuum tester.

Or the mickey mouse version I used: flip the head over and fill the valve pockets with very thin oil and see if it leaks past the valves. You can take motor oil and thin it with mineral spirits.