The Superhawk from hell...

[Jlovvorn]

Ok, here are my hack measurements.

First, is the bores. I took measurments on top and bottom, and for each bore I checked four angles. Straight up and down, across, then both diagonals.

Here are the results for the top of the cylinders:


CB77 rebuild 058 by Jrlovvorn, on Flickr


CB77 rebuild 057 by Jrlovvorn, on Flickr

As you can see, the numbers are under 60mm, which doesn't make sense to me. The book says 60mm, with a wear limit of .10mm. Using the .10mm tolerence, it seems like right side is out of round.

Here are the measurments taken from the bottom:


CB77 rebuild 060 by Jrlovvorn, on Flickr


CB77 rebuild 059 by Jrlovvorn, on Flickr

These look to be within .10, in terms of roundness.

I then measured the pistons, just for fun.

Here are the results:


CB77 rebuild 062 by Jrlovvorn, on Flickr


CB77 rebuild 063 by Jrlovvorn, on Flickr

I then put the pistons into the cylinder, and tried to measure the clearance.

This was tricky, as the feeler guage hits the first ring pretty quick on top.

These readings were taken on one side of the piston, with the piston squished to the opposite side as much as possible. In other words, there is half this much clearance on both sides under normal conditions.


CB77 rebuild 061 by Jrlovvorn, on Flickr

Yes, these numbers are totally inconsistent with the numbers above as to the cylinders and the pistons. If my numbers were correct, the pistons would not even go into the cylinders. And yet, I have gaps that are beyond the spec of .1mm.

And here are pictures of how I took the clearance readings:


CB77 rebuild 056 by Jrlovvorn, on Flickr


CB77 rebuild 054 by Jrlovvorn, on Flickr

Thoughts? Criticisms? Witticisms?

[G-Man]

I can see that you are having fun!

A piston is tapered and oval. The largest diameter is at 90 degrees to the gudgeon pin at the bottom of the skirt. You can use this part to gauge the wear in the bore. The clearance between the top of the piston and bore is not a good measure as this is the smallest part of the piston. The rings take up the clearance.

Biggest wear will be at the top of the bore (front and back) just below the top of the liner where the rings reach up to.

So to detect wear you can compare the dimension at the top of the liner in two planes. This will hampered by a ring of carbon just above where the rings travel to.

It looks like your cylinders are standard at 60mm. Digital calipers are not the most accurate tool but are handy for getting the nominal size.

See exerpt below for a simple technique below.

G

[Jlovvorn]

Would this be a bad time to disclose that I failed high school math?

Fortunately, a member has taken pitty on my horrible mechanic and math skills, and is going to take a look at the cylinder for me.

I will report back when I am ready to reassemble.

Thanks a ton everyone!

[Jlovvorn]

Ok, thanks to LM, I am back in business with a cleaned up head and valves, pistons and rings, and cylinder in spec!

I am going to assemble everything this weekend, and hopefully not find out I am off a tooth on the cam.

I am terrified of that particualr error, so if anyone has tricks or thoughts on it, please share.

[Jlovvorn]

Well, I got it back together, and with only three emergency calls to TX.

But will it run?

Will post pictures soon.

Going to install and fire it tomorrow.

[Jlovvorn]

So, its back in the bike and running, but still getting a drop or two of oil from the head gasket. Looks to be coming right from the o ring spot. I used new rings and some sealant.

Here is the top end job repair log:

1. Refurbished head, cylinder, pistons and rings back from LM. Look nicer than NOS! Wow.


Untitled by Jrlovvorn, on Flickr


Untitled by Jrlovvorn, on Flickr

2. Bottom end after a little clean up, first gasket down


Untitled by Jrlovvorn, on Flickr

3. First check - CHR cam chain is not cut.


Untitled by Jrlovvorn, on Flickr

4. A bycycle chain breaker and a tap and problem solved.


Untitled by Jrlovvorn, on Flickr

5. Second check - the master link is not a typical master link - I don't have any means to put this link on. Third check - the old master link is a tiny bit different pin pitch and won't work. Decided to resuse old cam chain. Terrible, but no real option.


Untitled by Jrlovvorn, on Flickr

6. Piston pins are really really tight. Needed lots of oil and a little work.


Untitled by Jrlovvorn, on Flickr

7. Pistons on and lubed. Clips facing up, rings arranged with gaps at 12, 4, and 8pm.


Untitled by Jrlovvorn, on Flickr

8. First set of rings compressed by hand and down. Definitely a two person job!


Untitled by Jrlovvorn, on Flickr

9. Both pistons in. The hard part seems over.


Untitled by Jrlovvorn, on Flickr

10. Don't forget the o rings on the knock pins!


Untitled by Jrlovvorn, on Flickr

11. Head is down with a little sealant on the two o rings. Time to face the cam chain and timing.


Untitled by Jrlovvorn, on Flickr


12. Points cam line pointed due north. So far so good.


Untitled by Jrlovvorn, on Flickr

13. Cam master link on with gap faced backwards, sprocket two marks on top with the horizonal line even with the head surface. Timing looks right. Hope its not off a tooth.


Untitled by Jrlovvorn, on Flickr

14. All lubed up on the top end and lid is on. Time to crank down the bolts to 15 (not enough FYI - see below). Don't forget to tighen two bolts under the plugs.


Untitled by Jrlovvorn, on Flickr

15. A little help from the lift and we are back in the bike, with tach, carbs, tensioner, and electronic ignition back on. Valves adjusted and ready.


Untitled by Jrlovvorn, on Flickr

16. Everything buttoned up and ready to go. Only three emergency calls to LM in Texas - not too bad.


Untitled by Jrlovvorn, on Flickr

17. It runs! (click or paste the link)

http://www.flickr.com/photos/79070021@N06/8246209118/

18. Bummer, its leaking oil. About a dime size puddle on the starter. Cranked bolts down to 18 and its down to a drop or two. Hope it seals up!

19. First ride tonight, it runs like a top!

Thanks beyond measure to Ed, and to everyone else that helped, and especially those that encouraged.

It's an amazing feeling to be done.

I want to go back in and replace that cam chain, perhaps when it gets too cold to ride.

[sarals]

Wow! Congratulations! It sure does sound sweet. I know you're pleased!!