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Author Topic: intake valves have no lash  (Read 1839 times)

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Offline YoungRider71

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intake valves have no lash
« on: February 15, 2012, 06:28:00 PM »
I have been slowly rebuilding my 74 750. Up to this point I have had little to no issue, but now I am assembling the rocker arm assembly and have no valve lash on the intake side of the motor. I thought it was some issue with my build but it is the same problem on all 4 valves. I can see the springs compress once I push the bar through the rocker arms. I need help with this one.
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Offline Patrick

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Re: intake valves have no lash
« Reply #1 on: February 15, 2012, 06:48:53 PM »
OK, here's shot in the dark. Did you remove the valves from the head as part of your rebuild? Are you positive you did not switch intake for exhaust when you put them back in?

I did that once with a Yamaha I rebuilt. I got those exact symptoms.

This is assuming you know how to adjust the valve lash.

Patrick
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Offline Don R

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Re: intake valves have no lash
« Reply #2 on: February 15, 2012, 06:53:59 PM »
Did you grind the valves and seats? That will sink them into the head a little deeper.
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Offline MCRider

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Re: intake valves have no lash
« Reply #3 on: February 15, 2012, 07:00:43 PM »
Quote from: YoungRider71 on February 15, 2012, 06:28:00 PM
I have been slowly rebuilding my 74 750. Up to this point I have had little to no issue, but now I am assembling the rocker arm assembly and have no valve lash on the intake side of the motor. I thought it was some issue with my build but it is the same problem on all 4 valves. I can see the springs compress once I push the bar through the rocker arms. I need help with this one.
To build on what's been said: I don;t think you could have switched the valves as they are so different you'd have known. But if you had the seats ground, the valve will rise up in the head a tad. In any event, have you backed off your adjusters? That's what they are for.

While your at it, but not to your point, you should look at the contact surface of the adjusters for pits and wear, often overlooked.
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Offline YoungRider71

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Re: intake valves have no lash
« Reply #4 on: February 15, 2012, 07:36:31 PM »
The truth is embarrassing. Need i say more. I had my uncle come down to my shop and take a look. I thought he was breaking my balls when he suggested I put them in wrong. But he made me remove the head and sure enough the valves were switched. Good news all the valves are straightened out. Bad news is i just returned my buddy's torque wrench over the weekend. Oh well, gonna have to by more tools.
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Offline KJ790

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Re: intake valves have no lash
« Reply #5 on: February 15, 2012, 07:55:14 PM »
What do you mean by "the valves were switched"? Do you mean you had the exhaust valves in the intake ports, or that you switched intake valves between cylinders?
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Offline YoungRider71

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Re: intake valves have no lash
« Reply #6 on: February 15, 2012, 08:03:01 PM »
Intake in the exhaust and vice versa.
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Offline camelman

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Re: intake valves have no lash
« Reply #7 on: February 15, 2012, 10:42:12 PM »
Awesome!  Congrats on not having a real problem, but good luck living this one down!!

My first engine rebuild was on a 1981 Honda Accord I bought with a blown head gasket when I was 16.  I had seven very large bolts left over when I drove it out of the garage.  A year later, when I destroyed two pistons from detonation caused by overly advanced timing, I had to rebuild the engine again.  However, after that rebuild, I only had three very large bolts left over.  The moral of the story is that you get better with practice  ;-)

Glad you got it fixed.

Camelman
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Offline YoungRider71

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Re: intake valves have no lash
« Reply #8 on: February 16, 2012, 05:26:43 AM »
I know this one is gonna stick around awhile. Lol. Hopefully this will be the last mistake i make for a while.
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Offline Patrick

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Re: intake valves have no lash
« Reply #9 on: February 16, 2012, 05:46:37 AM »
There really is nothing to be embarrassed about, YR. I'd rebuilt at least a dozen motor before I switched the valves on that Yamaha. It happens. In my case it was probably stupider, since it was the third time I had been through an XS11 engine. And the valves were 4mm difference in size. But they sure looked right.

Patrick
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Offline YoungRider71

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Re: intake valves have no lash
« Reply #10 on: February 16, 2012, 06:01:00 AM »
The only thing I can think happened was I flipped the head and grabbed the wrong valve. I now can really see how haste makes waste. I only seem to get a few hrs in a week so it sucks because it sets me quite a ways back.
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Offline MCRider

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Re: intake valves have no lash
« Reply #11 on: February 16, 2012, 06:40:48 AM »
Quote from: YoungRider71 on February 16, 2012, 06:01:00 AM
The only thing I can think happened was I flipped the head and grabbed the wrong valve. I now can really see how haste makes waste. I only seem to get a few hrs in a week so it sucks because it sets me quite a ways back.
makes me feel better about (stupid) things I have done, so all's not lost.  ;)  I'm only working on a project a few hours a week too, and a mistake really slows things down.
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Offline YoungRider71

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Re: intake valves have no lash
« Reply #12 on: February 18, 2012, 10:54:08 PM »
Got the valves set correctly, finished adjusting them. Everything was going well until I started putting the cases on this evening and realized I may have lost all the case screws. I think i should have called this thred " the woes of my first engine rebuild" lol. I guess this is how we learn.
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