The Engine Rebuild
An Overview
This engine is intimidating at first, but if you put your mind to it and
develop a system, the rebuild will go smoothly.
Tearing down an engine isn't hard. You do need to track all the removed
parts. I use a ton of freezer size zip-lock bags and a permanent marker. Put parts into the
bag and mark it. Also helpful:
- Mandatory. A shop manual. Get one from
Helm
for about $36.00 plus S&H.
- A clean work area.
- Metric wrenches, sockets, and Allen wrenches. Some specialty tools may be
needed ,and are addressed in the manual.
- Empty boxes make useful storage vessels. Egg cartons help keep parts
associated with the correct cylinder, carburetor, etc.
- A Dremel tool is helpful for cleanup of carbon, rust, etc.
- Measuring devices such as a caliper, micrometer, dial gauge, metric
feelers.
- Access to a parts cleaning solvent machine is helpful, as is a glass
beading machine.
- A microfiche of the entire bike from Honda. I found mine at a local
dealer. he charged me $5.00! I see them on
from time to time, but it
seems folks overpay for them. Be careful. I may, if I have the time, post
the microfiche on this site.
Next, find a place that still has or can get CBX parts. My sources are listed
on the links page.
Teardown and buildup overview.
I followed the shop manual, and now have the engine in as many pieces as
possible, I think! This engine has one known problem, a broken left
exhaust camshaft and bent #3 valve. We'll see what else may be damaged.
I have a price
of $183.00 for a new one.
Used ones seem to be around the $100 dollar range. I found a set of low mile
used 79 cams from Rick Bentley at CBXSupersport.
In 1980, Honda reduced horsepower to 98 by changing the cam profile. The 79
cams will help restore the lost 7-8 horses. I'm also replacing the following parts. Most of them
have measured to be within spec, but I have the engine this far, and it seems
stupid to have to come back for a part later. I'm replacing :
- Main and connecting rod bearings. From Midwest Action Cycle. They don't look too bad, but these are
the heart of the machine. It's a sort of puzzle to know which ones you need.
They're color coded, and you must cross reference markings on the case, rods,
and crankshaft in order to know which ones you need. The manual explains
this. The cost is about $8.20
per bearing. That's 14 main bearings and
12 rod bearings. Total- about
$220.00.
- All gaskets. Honda makes an overhaul gasket kit that contains every gasket
you would need for a total rebuild. Head gaskets, o-rings, base gaskets, side covers,
valve cover....even new valve seals are part of the kit. Total- around
$260.00. Nothing like an oil tight engine!
- Piston rings. Tim's CBX has them for $25.40 per set....times six equals
about $152.00.
- Assorted oil seals for the various shafts.
Approximately $55.00.
- A fellow CBX'er sent me a complete set of valve springs, keepers,
shims,
etc. from
a low mile engine. Cost me $75.00. Rumor this engine was over revved, so
springs are a good idea. Thanks Charles Weidman!
- Engine paint from Tim's CBX cost about $25.00. I'll paint the engine, shine
up the aluminum, and then clear coat the entire thing. UPDATE-
On second thought, I wouldn't clear coat the head. I used a high-temp
clear coat, but the head heat has started it turning yellow anyway. Not a
big deal, but I'll repaint the head on the bike over the winter.
That's most of the big stuff. An occasional seal, bolt, etc aren't to be
ruled out. The parts I'm replacing will give me a like new engine. I'll have to
perform a factory break-in period to let things seat. Then it's business as
usual.
[ The Bottom End ] [ Pistons and rods ] [ Top end ] [ Carburetors ]
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