Checking the Valve Clearance and Finishing Up the Top End

With the new cams installed last night, it was time to check the valve clearance and finish up the top end. It's been a busy few nights, but we've made a lot of progress. I think the biggest job to get ready to race is now done. The next project will be to attach the front head to the stabilizer, get the manifold situated, the carb reinstalled, and the exhaust put back together.

Tonight's project started with replacing some o-rings for the pushrod covers.


The bottom of the pushrod covers fit inside a rubber gasket inside the lifter cover that I wanted to replace. In order to remove it, you need to first remove the cover over the lifter. Inside the lifter cover is a rubber gasket that fits inside. I replaced all four.


There is also an o-ring in the head where the top of the pushrod cover connects to the head just below the rocker arm. I replaced the four o-rings as well.


I also needed to replace a small o-ring in each head for an oil passageway.


There are a couple of different ways to make sure you have enough valve clearance, but this was a pretty easy and straightforward way Dan at NHRS recommended. You pack some clay into the pockets on the top of the piston. Make sure and cut away any excess with a knife. What you're measuring is the amount of clay the valves squish into the pocket when the valves open.


With the gasket on top of the cylinder, torque the head back into place. We added a little bit of oil on the head bolts. Don't put so much that it's dripping or puddling inside the head bolt. You just want a thin film of oil so there is some lubrication.

We buffed up the head bolts on the bench grinder and then torqued down the heads to speck. I think I've spent more time with my torque wrench over the last few days than I have in the last 12 months. We decided that a "real man" knows how to use a torque wrench.

NOTE: It's a good habit to set your torque wrench back to just shy of zero before you put it away. I also keep them in the plastic boxes they came in when I put them back in the toolbox. I treat my torque wrench the same way I do my caliper and micrometer so I can be confident it will work like it's supposed to when I need it.


With the head torqued down, slide the pushrods into the top of the lifters. You don't need to worry about the pushrod covers at this point. Torque to spec the nine fasteners on the rocker box. Start with the four bolts on the lifters—starting with the two over the pushrods. On the forward head the allen screw on the left side is going to be your least favorite fastener because it's hard to get and you'll need a short allen wrench to get at it. A ratchet won't fit.

It might take a minute for the lifters to bleed down, so you'll need to wait for that before you rotate through the stroke or you could damage the pushrods or the lifters. When you can turn the pushrods in your hand you'll know you're ready.

With the bike in 5th gear and using the rear wheel, push the cylinder through top dead center. We did it a couple times to make sure we got an accurate clearance measurement.


Dismantle the rocker box and remove the cylinder head and the clay should look something like the image above. You'll want to measure the cross section to see how much clearance you have. You could use a mechanic's ruler (which is what Dan at NHRS says he usually does) or you can do what we did and use a caliper.

You want to see a measurement of at least .060" of clearance on the intake and at least .090" of clearance on the exhaust side. We had plenty of clearance.


Once you've verified you have the clearance you need, it's time to torque up the head again—for real this time.


Figuring it might take a second or two for the oil pump to get oil back into the rocker box, I added some oil so it wouldn't be completely dry when it was time to fire up the bike.


I'm not sure why the rocker box cover comes in two pieces, but it does. You'll want to install the rubber gasket in between both pieces of the cover before you torque it down. I tried to be patient and work through tightening all these fasteners in 1/4 turn increments so as not to tweak anything while tightening down the covers.


We put both the forward and rear head on, then put the rocker boxes on both jugs, and put the rocker box covers on. I don't know if it made it any easier to remember the procedure because we double-checked the torque specks before we tightened every set of fasteners anyway (just paranoid I guess). But it made sense and felt like the right thing to do. Because the rear cylinder was so much easier to do, I would do the front cylinder first so I could relish the rear cylinder. As it gets later, it doesn't take much to entertain me I guess. That being said, there was a clearance issue with the back fastener on the right, I needed to estimate my final torque based upon the other three because I couldn't get my wrench in there.

Steve said he couldn't hear my wrist "click."


With the big bore kit and the new cams installed the little hotrod is starting to look like a motorcycle again. The biggest part of this project is completed. I know I've said this several times, but as intimidated as I was when I decided to take this on, it wasn't anywhere near as difficult as I thought it would be and with the crux of the project done, I have to admit it was very straightforward and I wouldn't be nervous about tackling this job again.

That being said, Steve commented about how it took the two of us a lot longer to do this than one of the guys in the dealership probably would have, but fortunately we didn't have the pressure of a customer waiting to get their bike back—so it didn't matter. We stopped several times to talk through what we were doing and double check ourselves. If there was any doubt about how something fit, we'd dismantle it and redo. Slow and steady wins the race to go fast.

I'm anxious now to finish her up and start to break her in.