I've talked with LoudMouse about this and got some good suggestions with an overview of how he builds up his engines. I figured I'd post up on the board and see what other people think on the subject.
I'll be taking my '67 CB77 down to the frame this winter and rebuilding it. I'm not focusing on a restoration, but rather a build to suite my tastes so nothing has to be correct to the year. All of you purist, don't worry, I've compiled spares of everything that I plan on modifying just in case I do want to go the all original route in the future :-)
My main concern in the first stages is rebuilding the engine. I like to ride for hours on end when it's warm and don't want to be bothered with roadside repairs or adjustments if I can avoid it. While I'd like to get some more power out of the bike, the most important thing to me is reliability. I'd rather the bike have the same power and run like a top for the rest of its life than have more power with the possibility that what I've done will cause any sort of issue down the road.
So, with that in mind, what do you all feel will make for a bullet proof motor? I'm mainly interested in bolt on items and DIY upgrades so no complex machining solutions or crazy welding additions. Example: what are the most reliable valves, pistons, etc. Doesn't matter if its overkill for the bike or the motor in terms of strength/composition. I'd rather spend a bit more on something and know that it will never be pushed to its limit than get something that's just "good enough." I realize that with the age of the bike, the aftermarket and OEM parts can be hard to find. If there's even a chance it exists, please mention it. Thanks.
What makes for a bullet proof engine?Put it back together the way the designers intended with correct OEM parts and you should have no trouble with it at all. They were bullet-proof to begin with! You could upgrade to electronic ignition, but if set to factory specs, the stock ignition works just fine. You could use aftermarket mufflers and air filters, but now is the mixture right, nope. Use all of the original brass in the carbs if you can. Pistons, rings, valves, etc, I would use OEM - right size, shape, weight, go for many tens of thousands of miles. Don't try and second-guess the Japanese engineering. Patience and attention to detail are the keys - don't settle for a part that's almost right, get the right one. They're almost all available from somewhere. If you have to cut a corner, make a mod, or use an a/m part, ask right here - someone will have already tried it and can let you know the outcome. Oh yeah, and don't idle with the headlight on for any length of time... I guess the engineering wasn't all perfect:) Good luck and let us know how it comes out!
Thanks for the feedback. Not trying to second guess Honda's engineering really. I know they built it to the best of their ability for the time. However, when parts are made, you have to take in consideration the technology of the time, and the budget they had to work with. Think of it this way...what are the common issues with the bike (like the idling issue while running the light)? I'm not familiar enough with the bike yet to point out much of anything. Does a certain part wear out faster than you would like? Does a certain part commonly break under repeated stress? Once you start thinking about it that way, I'm sure you'll start realizing that most things are not as trouble free as you might think. Sometimes on the older bikes, newer technology allows us to make replacement parts far better than the originals. I'm sure if honda went back and was allowed to remake the engine but had to keep the overall mechanism the same, the difference would be night and day just from better metal tech or machining tolerances. New seals and gaskets - no old, or almost OK parts. Good cam chain, points are OK, but I prefer electronic ignitions for reliability, but that's a personal call.
The key for me is attention to detail. Stock valves are OK if they are in good condition, but old worn valves don't cut it. Cases must fit together perfectly. Threads on cases must be chased and cleaned out. I like to try to match parts for weight where possible, but within reason. All to make it easy for the motor to do its job and reduce lost/wasted power. Get carburation and timing spot on. Almost right or close enough are not the way to go. Do it right. It's about getting the fundamentals right.
Hi,
Do all those things above, and make sure that the main parts are according to spec (bore / pistons, crank, transmission). Check if the oil pump is within specifications, it increases the life expectancy of the engine. Invest in good oil, mineral or synthetic (you will find enough opinions when using the search function), and change regularly (around 1000 miles), this is probably one of the most important thing to do next to warming up the bike before let it perform. Start gently with riding, and open the throttle when warmed up. Maintain it properly, on a regular base and with attention. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
Jensen writes with perfect sense and I agree with his and all the above replies entirely. My contribution: I intend trying to find a single- or two-row oil cooler to fit to my CB during this winter's rebuild. I'm thinking that it should be fitted below the starter motor and piped into the scavenge (return) oilway, as there's probably insufficient pressure to usefully push oil any higher. A cooler will assist the oil in retaining its viscosity during its time in the crankcasings, thus increasing the lubricant's useful lifespan. It should still be changed at ±1k miles.
I'll keep you posted regarding any findings and obviously I'll ask for constructive comments.
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