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Dianne's C77

Want to keep a Restoration Log? Post it here! You can include photos. Suggested format: One Restoration per Thread; then keep adding your updates to the same thread...
DianneB
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Post by DianneB » Thu Aug 13, 2015 11:59 am

Tried some gas down the carb, even some gas directly into the cylinders, new plugs, and still no change - it acts like it is trying to start but not quite making it.

The compression is nowhere near what it should be and I can only conclude that after running for a few minutes last week, something in the valve train changed or something with the rings. Maybe warming it up caused something to stick or to un-stick.

It is time to stop puttering around the edges and do a complete engine rebuild: to replace rings, maybe pistons, hone or re-bore the cylinders, do the valves, and return the engine to like-new condition.

With the engine "breathing" properly and having proper compression, it ought to run just fine.

(I have been tinkering with engines most of my 66 years and never had problems like this before.)

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G-Man
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Post by G-Man » Thu Aug 13, 2015 1:31 pm

Dianne

Let us know how that works out. Not a big job just to pull the head and barrels but once you get started you'll just want to do the whole thing..... :-)

It sounds odd but you may have just got stuck rings and the extra heat from running may have just sealed the deal....

There are one or two miracle potions that you could try but probably best just to get stuck in.

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

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sarals
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Post by sarals » Fri Aug 14, 2015 2:05 pm

Dianne, keep us informed! Photos of the rebuild, too?
1965 CB77 305 Super Hawk
1989 NT650 Hawk GT
1981 Yamaha XJ550 Seca

DianneB
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Post by DianneB » Fri Aug 14, 2015 4:57 pm

Stuck ring indeed! How about SIX stuck rings! No wonder she had no compression! Gasket set, oil ring set, and new rings on order. Valves to be checked yet and then I will open up the bottom end to fix the kick-start ratchet.

Rather than copy all the pictures here, I'll just send you to my Web site.

http://www.diannebest.com/Projects/Hond ... ream2.html

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sarals
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Post by sarals » Sat Aug 15, 2015 12:44 am

Six stuck rings! Wow.

The bores did look good from the photo. One of the pistons looked scuffed, but it was really hard to tell for sure. How was the cam chain tensioner roller, and the guide roller?
1965 CB77 305 Super Hawk
1989 NT650 Hawk GT
1981 Yamaha XJ550 Seca

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sarals
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Post by sarals » Sat Aug 15, 2015 12:44 am

Oh, the head looked pretty decent, too.
1965 CB77 305 Super Hawk
1989 NT650 Hawk GT
1981 Yamaha XJ550 Seca

DianneB
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Location: Manitoba, Canada

Post by DianneB » Sat Aug 15, 2015 6:19 am

sarals wrote:Six stuck rings! Wow.

The bores did look good from the photo. One of the pistons looked scuffed, but it was really hard to tell for sure. How was the cam chain tensioner roller, and the guide roller?
The bores feel really good - no ridges or scratches. A few minutes with a hone will bring them up nice.

One piston is a little scuffed but it will clean up fine. They will both need the grooves cleaned up with a file and the heads wire-brushed.

The rollers both seem pretty good as is.

The damage to the engine looks to be mostly from sitting for years rather than being "run out".

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