The motor on my CB77 is finally all apart and clean, ready for reassembly. I'm planning to take the big pieces down to the (excellent) local machine shop to make sure the decks are all flat/parallel. Before putting it all back together, I wonder if I can get a few more ponies out of it without risking damage or hurting driveability by:
1. Polishing the intakes
2. Balancing pistons and crank
3. Shaving the head to raise compression
4. Advancing the spark a few degrees.
Any wisdom on this would be much appreciated.
Simple mods to add HP?
Re: Simple mods to add HP?Just my advice!!!!!!!!!!!!!! Ya can spend all the $$$$$$$$$$$ ya want and I must ask! What do you expect to gain? You will find that even though you don't deck the parts the gaskets will do the job.
So you spend your money paying for the mods you mention and for one will tell you that you will not be able to tell any real difference as to power or performance. The only item which truly made a noticeable difference (other than $500.00 cams and cam followers) is/was the electronic ignition. I have a question. Why would you spend lot of $$$$$$$$$$$ to add a couple of HP? Even when these bikes were popular and all over the streets we knew that the true/real power was in the ability to gas/shift and have bigger (nuts) than the other guy/person when challenged. So you spend lots of $$ and you think the bike is the tits and you go do your thing and find that what you have is a lot of $$$$ tied up in an engine that could/may be a grenade and go POP!!!!!!!!!!! I will assure that you will never/seldom ever be at a red light and have another small engine bike stop next you. I ride my 1963 CB77 (standard bore) and haven't had a bike with an engine smaller/close cc at the same red light I was at. Now if you really want to spend the $$$$ I can do all that you request. All you need to do is ship the engine to me and be prepared to pay for what you ask for which will be more expensive at other engine builders and in the end will cost a lot and add a couple of HP. Let me know when you want to waste your $$$$ cause I can do the work and take your $$$$$$$$$$$$. ......................lm
Gee, mouse, don't be so darn wishy-washy. Tell us what you really think.
Ok, so it's dumb to try to get more out of it. How about the balancing? My neighbor had a CB77 back in the 70s and said it was a real boneshaker. Keep in mind I've never had this one running and don't know what to expect. I brought it home in five boxes - the PO's unfinished resto project.
High Bob, something I noticed, is how inacturate the coupling of the two cams is. I made a special adjustable coupler, to set each cam correctly for each cly. The problem was that in the process, I lost the centrifugal advance, and had to run fixed timeing, which meant, push start only. The motor ran very smooth, it was a fun project. Also, I had chosen, from the 2 most similar cams, from every thing I had to chose from, so that helped too. I am planning on balancing the rebuild I am doing now, it is easy to weigh the pistons and then remove alittle to even it up. Delco, built in resister coils make GREAT spark from my stock points and condenser. In 1983 I rode my bike in the Craig Vetter gas milage contest, (laguna seca) got 103 mpg
Dave
I ride mine during the summer and don't notice any Bone Shaking vibration other than when it's running/parked on the center/side stand.
Like the feller below says ya can make the pistons the same weight and that won't be that tough. I saw a set of Yoshamora (sp) pistons/cams at the Barber event and was shocked to see how poor the machine work inside the pistons was. Looked like a deburing tip was used and was rough as can be. I don't know of anything that can be done to the rest of the engine that would overcome that 180 degree crank syndrome. I'm of the opinion that HONDA designed a great engine (could be why so many are still around compared to others) and that as close to stock as one can keep it is the way to keep it dependable and not spend a ton of $$$$$$$ to gain little. ..............................lm
I'll venture into the fray lightly here....
After having had the internals gone through, had the obligatory porting and polishing done, I can't really say that any of it caused a power gain (If you want to see the full financial damage, check out 'SuperHawk Meets Triton' in the 'Custom' section of the Forum). I found that I got more out of electronic ignition, a freer flowing muffler and, dare I say this in the presence of LM, my Amal carbs (though I'm sure that a pair of well set up Keihins will do the trick too!). As well (not that I want to speak as some kind of 'voice of experience' -- I do have a 'wallet of experience', though!), I had a CB900f back in the '80s, and I spent untold amounts of money on all the internal and external goodies (983 Wiseco kit, CB1100f cams and carbs, high output alternator, coils, K&N Stage III Jet kit, Dial-A-Jet, SuperTrapp exhaust, port/polish, shave the head, 11:1 compression, blah blah blah), and I didn't find any big power increase. What I DID have, however, was difficultly in keeping the bike in proper tune, and I actually ended up blowing a piston. So, when all is said and done, I learned that if you're going to to any internal mods, you do them in moderation so that you don't end up with an unreliable handful that you spent a lot of money on. As I say, I'm no mechanic -- I just pay for the stuff!
HP and vibrationAn increase inpower can be had by going to CB450 carbs and installing the JC Whitney Dunstall style mufflers. Anything else will cost big bucks and only give minor gains like Loud Mose said.
I picked up a set of carbs on ebay for $ 10 and the new rubber carb mounts cost about $25. Vibration is another issue. Typically with a Superhawk and the 180 crank the carbs are not synced. This will also limit your top end and acceleration. In the 60s I would race CB77 for to end with my stock looking CB160. Generally I would be about 5-7 mph faster, unless the Superhawk was tuned properly and then It would be a draw. The 160 had CB72 power jet carbs, a 175 kit and the Dunstall type mufflers. To sync the carbs is simple 1. Turn off the fuel. 2. Back off the idle screws all the way. 3. Scew the cable adjusters at the top of the carb all the way in. 4. Pop the float bowels off. 5. Place thumb and index finger from the left hand on the tips of the needles protruding from the main jets. 6. Now slowly open the throttle with the right. 7. Turn the adjusters at the top of the carb to take up slack and get both needles moving at the same time. 8. Replace the float bowels. 9. Turn on the fuel. 10. Open the throttle slightly and start the engine. 11. Now turn in the idle screws to hold the idle. This should improve vibration even at idle. ALso getting the points synced at full advanced is important for a reduction in vibration and increase in HP. The electronic ignition makes this a no brainer.
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