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Here's
where all the fun is! 
The head on this bike is massive. It's about 2 feet across, and houses 24 valves. I got a hold of a valve spring tool from my friends at Cycle Adventure Ltd II in West Chester, PA. Removing all the valves takes time. Mark each valve and accompanying hardware so they go back into the same valve guide.
At this point I found a bent valve. 
This called for a closer inspection of the area. Indeed, a closer inspection
revealed
a cracked valve guide also. Looks like I'll have to get the head to my Honda
dealer for some work. I ordered the valve and guide, and the dealer put the
guide in and cut the seat. Don't forget the o-ring for the guide. All others look fine. Now the work starts.
I cleaned the carbon from all valves, ports, guides, and domes. I inspected everything closer, and all is well. Then, using a fine lapping compound, I lapped all valves. It doesn't seem like a lot of work until you realize there's 24 of them! I made sure that I had a nice clean, bright, seat on each. All look fine, so it's time to place the valve seals and proceed.
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*Note: each valve has 2 spring seats associated with them. They are in essence hardened washers. There's a large and small. They go in before the springs are inserted. Be sure that you install these, because the aluminum head material is too soft for the springs to seat on. |
Next, install the valve springs (inner and outer). The smaller winding goes against the head. I used a set of springs from a low mile engine. They all measured within spec. Here's the fun part. Grease the valve stem, and insert it into the valve guide. Slowly rotate it as you insert it. This will ease it past the new valve seals. Then, install the retainer. Now, use the spring compressor to compress the springs just enough to insert the keepers. Sorry, but it's just not as easy as it sounds! I had a hell of a time getting the keepers in. And nothing like having 48 of them! Just be patient, and you'll finish. A small dab of grease on the end of a screwdriver can help you get the keeper in. I used a set of needle nose pliers.
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*After installing all the valves, check them for leaks. You can use rubbing alcohol, etc. Spray or pour a small amount into the intake and exhaust ports. Then check for any leaks around the valve seats. If nothing shows, you're OK, if you see some seeping by, remove the valve, lap it again, install, and recheck. Keep in mind that they only need to hold for a few seconds. Don't expect them to hold the thin liquid for hours - they only need to keep compression for a hundredth of a second, right? |
With the valves in, oil the lifters and insert them with the shims*.
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*: There are "A" and "B" buckets (lifters) for the valves. They are identified by matching the buckets grooves to the A or B stamped in the head. Two grooves are an "A", one groove is a "B". This info was not in my service manual, and could have been a big problem had Ken Watson not let me in on this "secret" Apparently, the clearances are different, and if not in the right positions, the engine would have locked up once the temperatures rose! Neat! Here's a copy of the information.Thanks to Brian Weir, here's some great pictures of the buckets detailing the grooves of the "A" and "B" types. Click on the picture for a larger view.
The "A" Type The "B" Type |
Now place the head gasket on, and lift the head onto the cylinders. Torque the bolts, and set the cams by the manual to insure proper timing. Use plenty of fresh oil on the cam lobes, and grease on the cam bearing surfaces. Torque all bolts in 2 to 3 steps.
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*Be sure to check the valve clearances before you close it up. Chance are, you'll need to find a supply of shims to get the clearances right. You'll also need a special tool to hold the lifters down so you can get the shims out. I ordered it from the Dennis Kirk Catalog. You can also get it from Tims. This small piece of metal cost $33.00. Unbelievable! But you do need it!. Use the chart in the manual to determine what size shim you need. I was able to trade shims at a local dealer, but not all were willing to do that. |
None really, if you read the manual and follow it step by step. Just be sure to use new o-rings and crush washers on all oil lines, etc. Careful with the valve cover gasket. A few dabs of Hondabond or similar will help hold it in place while you lift the valve cover on.
Also, it's possible to install the cam halves 180 degrees out of phase. A quick way to check for proper installation: if the cam lobes for #1 are pointing toward the spark plug, the lobes for #6 should point away from the plug.
