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:

1. Mandatory. A shop manual. Get one from Helm for about $36.00 plus S&H.
2. A clean work area.
3. Metric wrenches, sockets, and Allen wrenches. Some specialty tools may be needed ,and are addressed in the manual.
4. Empty boxes make useful storage vessels. Egg cartons help keep parts associated with the correct cylinder, carburetor, etc.
5. A Dremel tool is helpful for cleanup of carbon, rust, etc.
6. Measuring devices such as a caliper, micrometer, dial gauge, metric feelers.
7. Access to a parts cleaning solvent machine is helpful, as is a glass beading machine.
8. 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. NEW- Here's the parts fiche link!

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 :

1. 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.
2. 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!
3. Piston rings. Tim's CBX has them for $25.40 per set....times six equals about $152.00.
4. Assorted oil seals for the various shafts. Approximately $55.00.
5. 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!
6. 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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