1979 CB750K wont start

[TOOLS1]

Sounds like they are adjusted too tight. Try removing all tension on the valve adjusters, and recheck.
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[Karl H]

Would I do that by unbolting the cam?

[shinyribs]

No.Remove the 8 plugs in the top of the valve cover.When you look down in there you will see the adjusters.They are on the opposite side of the rocker arm of the valve itself.Make all of them slack and try the air again to see what leaks then.

[TOOLS1]

Just a thought. I know, you said that your bike is a 79, which is usually a DOHC. However there were some SOHC bikes sold in 79. Which do, you have?
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[Karl H]

Yeah its a DOHC cb750k.
I would assume taking the camshafts off is the only way to take pressure off the valves.

[TOOLS1]

I don't have any experience with the DOHC, but I think, you are right.
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[fighterDaz]

Hi, I have nothing like the experience of the guys on here on cb's, but if it ran before it shouldn't need anything replacing. I think from your description, it is engine timing or fuel. Dont get to confused, it is so easy to start getting deep into other areas, these engines are simple. I would try to start the bike again, remove a plug and see if its wet with fuel (back to basics here), if wet, you have fuel, if not its carbs. If you have fuel (wet plug) its timing, ignition or engine, if you left ignition timing alone it will not be that, but you did change the engine timing....fD

[shinyribs]

Oops. I keep forgetting not all bikes are SOHC. My bad. This has me baffled. I'm anxious. To find out what's up. I know you are too.

[TOOLS1]

"I pulled the engine, took off the head, lapped the valves, and inspected everything else."

This, the compression, and leak down test's have all ready shown that it is a valve problem. I think when he lapped the valves in he did not get them adjusted right. And DOHC valves are not easy to adjust.
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[Piute]

 I believe you to be right as them being to tight TOOL MAN

[shinyribs]

Sounds logical to me.I really want to see the inner workings of a DOHC someday.I hope i never see the inner workings of mine,though

[Karl H]

Well I took off the cams so there would be no pressure on the valves and re-tried the leak down test. It stopped the leaks out of the exhaust but the air is still escaping out the intake in a big way. My guess now would be stuck valves.

In other news i'd like to thank everyone who is helping me get to the bottom of this, your a huge help.  

[shinyribs]

Getting closer!

[TOOLS1]

Or bent valves. If they were too tight the piston might have hit them.
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[shinyribs]

I was thinking that,but didnt want to be the bearer of bad news.I also wasnt sure if these bikes would do that like a v8 would.Now i know

[TOOLS1]

I'm just cruel. Just ask my kids.
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[shinyribs]

No,no."Cool"    they said you were "cool".Turn down that all rap music and you'll be able to hear them better

[fighterDaz]

Dont leave us in suspenders dude, have you sorted it yet?

[Lucky 1]

I cannot figure out what you are doing.
Do you have a Honda workshop manual? You have to have that.

Many beginners take off the carbs and do not keep them upright, they
turn them upside down or or on their side and then if any debris is in the
float bowls it can slosh around and clog up the jets or float needle.
The float needles may need replacing if it has sat for any length of time.
Also if you did not clean the idle jets then all bets are off.
I think those carbs have the accelerator pump or pumps and those have to work properly too.

 You say"I hooked up the air" but you do not say where you hooked it up to and
what you were testing or which cylinder etc.,.. Was that cylinder the air was going into on the compression stroke, with both valves closed?
We also do not know how many miles are on the motorcycle.
Sometimes you cannot just lap valves. They often need the seats re cut first.
If the points gap and DWELL are not right that can keep it from running.
You cannot gap a set of used points if they are pitted. It will not work right.
The cam chain slack must be taken up BEFORE the valves are adjusted, or you have wasted your time.
How do we know that you got the cam chain on correctly?

Here is what I would do if I got that bike in my shop.
First I would make sure that when the timing marks are lined up that the cams are in the correct position.
Then If they are, I would do a compression check. If that is OK then I would take the carbs off and make sure they are clean and functioning properly and re install them. All adjustment screws in the correct position.
 Finally I would make sure the battery has a full charge(13.2 volts) and see if when the engine turns over it has spark (plugs gapped), at the right time.
Then take the gas tank and filter off and clean it and install a new filter.

Then it WILL start.

[Karl H]

Sorry to leave you guys in the dark for these past few days. I haven't had a chance to even see my bike much less work on it. Darn job getting in the way of my fun lol.

donald:
Yes I have the shop manual
At this moment I'm not too worried about the carbs being the problem
I first did a compression check and found i had 30psi on the #1 #2 and #4 cylinders and 100psi on the #3 cylinder i did a  leak down test and had air that leaked out of the exhaust and intake so i decided to  eliminate  valve timing from the equation and i took off both cams. I then re did the leak down test and had air still leaking out of the intake.

so now that plan is to find a strong friend to help me wrangle the engine out and back up on the stand so i can pop the head off and figure out how i messed the valves up.