New member needs answers

[jetts68]

Hi all
Just got my fingers on a 1980 cbx1000 cb1 27000km black twin shock. It's a tired all original except for the exhaust. It needs a complete dismantle and rebuild. The bike has not been started since 2004. I have only hand cracked the engine and will not attempt to start it till I dismantle the engine and inspect its guts before a complete engine and carb rebuild.
I have hundreds of questions a lot of which have been answered through searching the forum.
My first question is more to do with suggestions. Should I go down the sympathetic restoration road leaving most of the bumps scuffs and aged appearance or go for a nuts and bolts polished rebuild this would never be a consort finish as a respray would be required. Or should I go down the full custom path.

[NobleHops]

How could anyone answer that for you?

Search your soul, new friend, and when you pick your path that’s when we can help. Where in Ireland are you? There is a tribe up in Dungiven area, also afflicted with CBXs. Plenty of top guys in England. As soon as you’re ready, we are.

N.

[jnnngs]

Welcome to CBX ownership.

How you approach the build is entirely upto you - just personal choice on the type of bike you want at the end of the work you put in.

I have written a book on restoring CBXs which you may find useful:

viewtopic.php?p=103556#p103556

[jetts68]

Yes I get your point. Thanks
I have stripped down the engine. I was removing the old solid head bolts to replace them with the upgraded spiral ones
. Unfortunately I've broken one of the 10mm cylinder head bolts down in the the hole of the top engine case, it's on the left side inner bolt induction side of the engine. It's matching bolt on the right side seems to enter the oil gallery. Am I right with this assumption that the left bolt also goes into the gallery. The reason I ask is I will have to drill out the remaining stud and most likely end up with swarf in the bottom of the hole. If it is an oil gallery this is not good. I have found another few problems in the engine. 1: the primary chain has rubbed against its oil sprayer. I am waiting on a second primary shaft gear to measure the chain. As I suspect this is how honda intended to measure it looking at the diagram in the manual. I do intend replacing all the chain's but would like to know if it's a stretched chain or adjuster problem. 2: number 1 conrod bearing is warped and number 1 main bearing is in very poor shape. The shaft journals and conrod measure inside spec so a new set of shells and a light polish of the crank will sort it out. 3: I've read 4th gear is a problem with these older engines I don't see any wear but might just change it out. Is there anything else I should consider replacing in the engine while I have it dismantled.

[EMS]

One minor thing: A true 1980 CBX is not a CB1. It is a SC03. Make sure you know what you have as the specs and part-numbers differ in some areas.

[daves79x]

The threads do not necessarily go into the oil galley, but in some engines there is bleed-through. You have no choice, drill it out then thoroughly clean the oil passages and you'll be fine. The smooth studs were fine, BTW. Can't imagine how you broke one.

Dave

[Larry Zimmer]

Did 1980 bikes have smooth studs?

[EMS]

NO. He has a 79 model. he said CB1. As he is in the UK, some of the paperwork may state 1980 because of first registration, but it is a 1979 model.
And the smooth studs did break. That's why Honda changed them. There even may have been a service bulletin.

[daves79x]

They broke for Honda after testing an engine to failure at redline for an hour or so. I've never heard of one breaking in service. That said, there was a bulletin - my Honda dealer installed spiral studs in mine for free. Kind of wish now I'd left it alone, just for originality.

Dave

[Rick Pope]

Mine has the smooth studs. So far, so good.....

[EMS]

Only owners of bikes with an engine serial number of up to and including..3478 have to "worry" about smooth studs. This are most likely bikes that were built in April and May of 1978, out of the first two months.

[jetts68]

The frame is cb1-2015xxx the engine is cb1e-2015xxx. There is 79 digits between engine number and frame. The bike is a French model from new. I suspect it was manufactured in 79 and sold in 1980.
It had spiral head studs. I was removing the head bolts to allow for preparation of the cases for machining work and restoration, as well as to measure stretch on the studs. Someone tread locked the studs into the case. Overdone it on the first stud before releasing the problem. So the cases are of to the machine shop this week. And started into the cylinder head dismantling. Looks like some serious valve work on the way.
What I can tell from the valves is number 3 and 4 cylinders where running lean and hot. Number's 1 and 2 are severely carboned up and number 5 and 6 looking good. I haven't cleaned all the valves and seats yet. But I've found one of the exhaust valves has a lot of pitting that looks like impact damage but no sign of damage to the cylinder chamber or piston. The valve seats look terrible. Once I've cleaned everything up and measured and inspected everything I'll consider what direction I'll take. If the majority of the valve train is within tolerance I'll keep it standered. If it needs a lot of replacements I'll go down the porting and oversized valves and seats route.

[jetts68]

The threads do not necessarily go into the oil galley, but in some engines there is bleed-through. You have no choice, drill it out then thoroughly clean the oil passages and you'll be fine. The smooth studs were fine, BTW. Can't imagine how you broke one.

Dave

Hi Dave thanks for the reply. When you say bleed through would that be from the main oil gallery or in general through the crankcase.

[jetts68]

Mine has the smooth studs. So far, so good.....

I'm jealous Rick is your bike a 78. I'd love to own a 78 original.

[EMS]

Mine has the smooth studs. So far, so good.....

I'm jealous Rick is your bike a 78. I'd love to own a 78 original.

You have a 1978 original. The VIN number with CB1-20 15... was most likely produced in November of 1978. The CB1 designates it as a 1979 model. Production for the CB1 version started in April 1978 and ended in February 1979. The spiral studs in your engine were factory installed.