The forgotten CBX

[DC354]

This is a continuation of my first posting which is in the introductions area.
viewtopic.php?f=108&t=8826

I will be using this thread to update the progress of the bike.

Last weekend I went down to Chilliwack to pick away at the bike some more. I was hoping to get the last 4 spark plugs out, but ended up breaking two more trying to wiggle them back and forth. With 3/6 broken off inside the head, I think it's time to cut my losses and take the head off.

I ran in to trouble taking the head off when the bike stopped turning over for me. This was when i was taking off the timing chains. I decided to skip the turning over step and just pull it apart. Thankfully i have a full Honda CBX manual to put it back together and time it...
Once the head was off, we inspected the valves and saw that most of them have been rusted in to place. Not good. 3/6 broken plugs and stuck valves (which I suppose is why it didn't turn over)

So at this point, it sits as it and i am strongly considering buying a new head with the valves installed. Then I can pick away at the head I currently have.
A new head with valves in decent condition is around $300. Not so bad?

[EMS]

Hopefully, the replacement head came with cam caps??

[daves79x]

If you can get a good used one that might only need the valves lapped and new seals installed, that's the way to go. Refurbing your head would run $1000-$1200 with new guides and valves. Don't throw it away, but I think you have the right idea.

However, the condition of the head/valves leads me to think the bike hasn't been stored in the best environment. Might be further evidence of that the deeper you go.

Dave

[Syscrush]

Also, a heads-up... Isn't the FSM wrong about the can timing procedure? Do some research about your manual and backwards came before you reassemble.

[EMS]

Also, a heads-up... Isn't the FSM wrong about the can timing procedure? Do some research about your manual and backwards came before you reassemble.

Page 6-22 in the Service Manual should have a later date than March, 1978 to show it has been revised. Mine is August 1978. It should say in the bottom paragraph :

"Make sure the cam lobes for the No 6 cylinder are toward outside"

[Syscrush]

Page 6-22 in the Service Manual should have a later date than March, 1978 to show it has been revised. Mine is August 1978. It should say in the bottom paragraph :

"Make sure the cam lobes for the No 6 cylinder are toward outside"

The wealth of knowledge on here never ceases to amaze me. Same goes for the array of wicked bikes.

[DC354]

Thanks for the heads up! I'll be sure to check my manual!

I am heading to Sumas Washington on Saturday to pick up a new head. It has 3k miles on brands new valves. Guy crashed the motorcycle and is parting it out on eBay.
Comes complete with cams too.

[DC354]

Also, a heads-up... Isn't the FSM wrong about the can timing procedure? Do some research about your manual and backwards came before you reassemble.

Page 6-22 in the Service Manual should have a later date than March, 1978 to show it has been revised. Mine is August 1978. It should say in the bottom paragraph :

"Make sure the cam lobes for the No 6 cylinder are toward outside"

So when you say outside. you mean towards the exhaust, correct? My manual says on page 6-21 "Position NO. 6 exhaust cam lobe toward the spark plug."
Can someone quickly confirm that this is in fact wrong?

[daves79x]

You can end up either way, depending on how many revolutions you went. The key is - Both one and six cannot be pointing in the same direction - if #6 lobes are pointing out, then #1 lobes MUST be pointing in. If #6 lobes are pointing in, then #1 lobes MUST be pointing out. Unless your manual clearly shows a picture of the lobes for #1 and 6 pointing the same direction (which is clearly wrong and only a few early manuals were wrong and showed this way), then follow the manual EXACTLY and you'll have no problem.

Dave

[DC354]

Hey thanks for the help Dave. Appreciate it. Finally got the head back together and everything seems to look right. Unfortunately i ran out of time this weekend. But the carbs have been cleaned up, and all i have to do is put some fresh oil in, throw the valve cover back on, throw the carbs on, and hope that it's timed correctly!...
Here are some more pictures from this weekend. Unfortunately the new head was painted black. Easily fixable though.

[daves79x]

Can't quite tell, but something looks funky with your tach drive cam cap. Also, take special note of the four center head cap nuts/washers. The center four on your engine are smaller than the ones intended for the head you have. You have small washers sealing the larger holes than were intended. Should work, but if you have a leak anywhere near the center of the head/cylinder, I'd look there.

Dave

[DC354]

Can't quite tell, but something looks funky with your tach drive cam cap. Also, take special note of the four center head cap nuts/washers. The center four on your engine are smaller than the ones intended for the head you have. You have small washers sealing the larger holes than were intended. Should work, but if you have a leak anywhere near the center of the head/cylinder, I'd look there.

Dave

Good to know. I did reuse the old washers under the cam caps, so hopefully that doesn't turn in to a problem.

[tevan]

Can't quite tell, but something looks funky with your tach drive cam cap. Also, take special note of the four center head cap nuts/washers. The center four on your engine are smaller than the ones intended for the head you have. You have small washers sealing the larger holes than were intended. Should work, but if you have a leak anywhere near the center of the head/cylinder, I'd look there.

Dave

Dave, Are you saying the inside 4 studs themselves are larger on the 81/82 head? Therefore the 79/80 are smaller cap nuts because of the smaller studs?

terry

[EMS]

The four center studs on the 79 engine are 8mm, as are the outside two on each side. The later engines have 10mm studs in the center like the two pairs adjacent to these on each side. Outsides are still 8mm

[DC354]

So if a leak occurres, could I theoretically just put the 10 mm washers under the 8mm cap nuts?