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Author Topic: CB750 page at Wikipedia  (Read 999 times)

Offline postoak

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CB750 page at Wikipedia
« on: August 05, 2017, 05:53:07 AM »
Has a list of the HP, torque, and other stats for all the "CB" models.  (I put quotes around CB because I've never been clear whether the Nighthawks are CBs or not). 



The early SOHC models are listed as having 67 HP, 44.1 foot-pounds torque, and weighing 481 pounds dry (which should make them about 513 pounds wet).



The Nighthawks made from 1991 - 2003 are shown as having 75 HP, 47 foot-pounds torque and weighing 463 pounds dry (which should make them about 495 pounds wet).


So, my question for those who've ridden both extensively, does the older CB have noticeably less acceleration than the new Nighthawks?

Offline mollusc

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Re: CB750 page at Wikipedia
« Reply #1 on: August 05, 2017, 06:36:43 AM »
(I put quotes around CB because I've never been clear whether the Nighthawks are CBs or not).


The model designation for the Nighthawk S is CB700SC or CB750SC.  They are definitively CBs.  I don't know about the other Nighthawks but I expect that they are similarly named.
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Offline sgarnett

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Re: CB750 page at Wikipedia
« Reply #2 on: August 05, 2017, 09:56:54 AM »
The last Nighthawk 750 was a CB750, but I've never figured out the suffix. Partzilla calls it a CB750A, but the A used to mean automatic. I've also seen CB750F2, but I think that was a European model.

Offline postoak

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Re: CB750 page at Wikipedia
« Reply #3 on: August 05, 2017, 11:08:23 AM »
Wikipedia says that the Nighthawk 750 was never called a CB750, just the "Nighthawk 750".  But back to my question for anyone who has ridden the early SOHC and the Nighthawk 750.

Offline sgarnett

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Re: CB750 page at Wikipedia
« Reply #4 on: August 05, 2017, 12:31:56 PM »
My title says CB750, I believe, but that doesn't help with your main question. Besides peak power, have you found dyno curves to compare?

Offline Larry Fine

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Re: CB750 page at Wikipedia
« Reply #5 on: August 05, 2017, 05:44:39 PM »
So, my question for those who've ridden both extensively, does the older CB have noticeably less acceleration than the new Nighthawks?

My bikes, in order:
1. 1972 CL-450 (DOHC twin)
2. 1973 CB-750 (SOHC four)
3. 1982 CB-750SC Nighthawk
4. 1996 Nighthawk 750

Numbers 2 and 4 qualifying me for your question, I'd have to say that, yes, the '91-and-up Nighthawk 750 is noticeably stronger than the SOHC version, presuming stock in all cases. Even more apparent is the improvement in handling, road manners, and comfort.

The 91-03 NH750's are referred to as CB750 on most web sites' parts-finders. Number 3, by the way, weighed just about exactly 100 pounds more than number 4, making it a whale in comparison, and for those still wondering, the SC suffix stood for Sport Custom.

Offline postoak

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Re: CB750 page at Wikipedia
« Reply #6 on: August 05, 2017, 06:26:02 PM »
How we're talking!  That's exactly the information I was looking for.

Online Raven

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Re: CB750 page at Wikipedia
« Reply #7 on: August 06, 2017, 06:41:54 AM »
The DOHC bikes had noticeably more power than the SOHC ones. I recently bought a 1983 Nighthawk 550 DOHC (CB550SC) for my daughter. It is a lot quicker than my '82 Nighthawk 650 SOHC (CB650SC) and the HP numbers support this.

Offline hppants

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Re: CB750 page at Wikipedia
« Reply #8 on: August 06, 2017, 12:38:20 PM »
Although not exactly what you have asked, I can comment on the 700s v/s the late model DOHC 750.  I've had both and put plenty of miles on each.  I've also found a way back country road with a mile of so of clean straight pavement, and I may (or may not) have hooked up with a friend on the other bike.  I may (or may not) have done this with my 700s v/s the late model and with my late model v/s the 700s.

The two bikes are so close in power, it's hardly worth mentioning.  The 700s has hotter cams, and revs a bit higher than the late model 750.  At about 6,000 rpm, she really wakes up and pulls hard to the redline.  But the 750 has better low end torque, and it's chain drive eliminates two power robbing 90 degree turns in route to the rear wheel.

I can tell you unequivocally that these bikes are equal in power on the street.

Offline postoak

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Re: CB750 page at Wikipedia
« Reply #9 on: August 06, 2017, 02:13:56 PM »
hppants - when you say "late model DOHC models" do you mean the Nighthawk 750 or something else? 


I notice on the Wikipedia chart that the CB750 DOHC was made in one form or another from 1979 - 1986 and 1992 - 1997 plus 2007 even though we in the U.S. didn't always get them and that's aside from the Nighthawk.

Offline hppants

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Re: CB750 page at Wikipedia
« Reply #10 on: August 06, 2017, 02:20:59 PM »
Yes - the '91-'03 750

Offline DesertDragon

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Re: CB750 page at Wikipedia
« Reply #11 on: August 06, 2017, 03:49:26 PM »
Perhaps a bit off topic, but hey - That's me on occasion.
I owned a 74 CB750 SOHC that had some custom engine work and a pretty loud 4 into 1 Kerker that seemed pretty quick at the time...
Well, at the time it WAS pretty quick because when introduced the CB750 was a "SuperBike!" 
The features it had were light years ahead at the time and its introduction pretty well swamped the competition.
The other "hot bikes" were 650 twins, if you were around back then to remember.

The 750 DOHC NightHawks on the other hand were built based upon extensive user survey feedback for what riders wanted.
Maybe it was just nostalgia, but sometimes people want what they don't think they can have, and when they can have it, they don't want it...

In any case, I remember an article on the 'Hawks entitled "More Mr. Nice Guy"...
The 91+ DOHC Hawks were built for what people said they wanted - Easy to live with, practical, and pretty good at everything.. i.e. a "Standard".

There are a lot more features on a bike to compare beyond horsepower, which is especially useful between thse two...
Here are a few I remember:

                      1974                            1996             
                      SOHC 750                     DOHC 750                           Impact                   
 
                       bkr3                           bkr3
Wheels            Laced/Spoke                 Cast                                     Adjust vs. No maintenance required
Brakes            1 Disc Front / Drum       1 Disc Front / Drum               Same setup
Alternator        Hanging on left side       Tucked behind cylinders         Narrower engine profile
Cam Chain       Requires Adjustment      Automatic                            Adjust vs. No maintenance required
Valves              8 SOHC screw adjusted  16 DOHC Hydraulic               Adjust vs. No maintenance required 
Ignition            Points/Condenser          Electronic                             Adjust / Repair / Replace vs. No maintenance required 
Horsepower      Less                             More                                    More is better!

While my '74 was a good bike, it required a LOT of maintenance to keep it running at it's peak. 
A couple of forays up to redline and it was time to do a valve adjustment, and adjust the cam chain.
A bump or two and it was adjust the wheel spokes... I fondly remember the dig, ding, thunk..
Well, I do remember, just not fondly :-)

Less easily identified in a list, but my '96 "feels" a LOT lighter and handles a lot more like a sportbike than the '74...
A good part of this IMHO is because the '74 was shod with bias-plys and my '96 has current century radials.
Tires have come a long way since then.

For me the bottom line is that the later versions are the refined great-grandsons of the earlier pioneer.
You can do a lot more riding with a lot less maintenance on the later versions.
That and the newer CB750 is Ultra-Reliable - Something I never could say (truthfully) about many other bikes I've owned.

My 2 cents.

 bkr3

DD






Keep the Rubber on the Bottom!

DD

Offline mollusc

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Re: CB750 page at Wikipedia
« Reply #12 on: August 06, 2017, 04:53:04 PM »
Let's throw into this mix the Japanese (and European?) spec CB750S which had a chain final drive instead of a shaft.  So you the maintenance-free DOHC engine without the loss of output power.  And then if you're a savvy user, you do the cam timing mod to bring the power surge down from 6500rpm to about 4500 and you've got a heck of a responsive beast.  No more actual HP than the other bikes, but delivered to the road a little more effectively.
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Offline postoak

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Re: CB750 page at Wikipedia
« Reply #13 on: August 06, 2017, 05:03:40 PM »
DesertDragon - the DOHC 1996 you are referring to is the Nighthawk or the F2?  I'm researching the F2 right now -- I'm not familiar with it at all.


mollusc - someone made the point one time that the Nighthawk was in someways a cheaper bike than the 700S -- chain drive instead of shaft, cable activated clutch instead of hydraulic, more plastic, and some other things I can't remember.

Offline postoak

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Re: CB750 page at Wikipedia
« Reply #14 on: August 06, 2017, 06:08:21 PM »
Ah, I see, the CB750F2 was a U.K. bike.  It was a lot like the Nighthawk 750 but a bit better.  It had triple disc brakes in contrast to the Nighthawk's single disc/drum combo, better shocks, and slightly different styling.

Offline Larry Fine

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Re: CB750 page at Wikipedia
« Reply #15 on: August 07, 2017, 12:18:14 PM »
And then if you're a savvy user, you do the cam timing mod to bring the power surge down from 6500rpm to about 4500 and you've got a heck of a responsive beast.

Details, please!

Offline mollusc

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Re: CB750 page at Wikipedia
« Reply #16 on: August 07, 2017, 01:23:40 PM »

The article below appeared in Motorcyclist Magazine, July 1989. It explains how to perform the cam timing modification on the CB700S, as well as a few other more invasive mods to improve performance over the stock setup.
Note that the author of the article accomplished the cam timing modifications by grinding the cam sprocket holes into long ovals; however, the same outcome can be achieved by rotating the cam sprockets by one tooth off the stock timing marks.
Someone came up with the following "angry face" illustration to assist in making the change:





====================
HIGH -FLYING NIGHTHAWK


Honda's Nighthawk CB700S is a brilliant motorcycle. Its designers successfully addressed most of the needs of us who ride our motorcycles everyday everywhere. It is comfortable, even after hours in the saddle, accommodating the needs of both sport and touring riders. At cruise, the tall sixth gear makes the engine seem more like an electric motor than a high-speed, high-performance sport engine. With an advanced four-valve design, hydraulic tappets, shaft drive and electronic ignition, the 'Hawk's power train is almost maintenance-free. Its handling is superior and the brakes superb.
As good as it is, though, the Nighthawk also has an important flaw: the engine is a bit peaky for real-world use. There is little power available at mid-rpm (below 5000), and acceleration can be positively lethargic in that range. We set out to correct that shortcoming and also to see if we could improve the 'Hawk's ride and road manners in the bargain.


THE ENGINE


We made two basic alterations to the Nighthawk engine. We altered cam timing to add power in the lower half of the rpm range, and we made changes in the intake and exhaust systems to allow more air to pass through the engine.


CAMS
The stock cams have extraordinarily long duration. Both intake and exhaust valves remain open for 276 crankshaft degrees when measured from .040 inch off their seats until .040 inch from closing. Cams with 260 degrees of duration would give a wider powerband. But since no aftermarket cams are available, we did not have the option of milder cam action, so we retimed the stock cams.
Honda closes the Nighthawk's intake valves late and opens the exhaust valves early, which favors high-rpm breathing efficiency and power. Our particular engine's cam-lobe centers were 120 degrees for the intake valves and 118 degrees for the exhausts -- the highest numbers of any stock engine I have measured. The cams' timing and duration largely account for the Nighthawk's low-rpm lethargy.
Engine tuners use the concept of lobe centers to compare cams with differing durations. In general, any engine design runs best with its cams set within a particular range of lobe centers. The actual duration of any one set of cams has little effect on the lobe centers that work best on an engine design.
To find a cam's lobe center, follow these steps. Measure its opening and closing positions and calculate its duration in degrees. Then, in the case of the intake cam, subtract the number of degrees before top dead center (TDC) that the intake valve opens from one-half the total duration number. For example, the total duration of the Nighthawk intake cam is 276 degrees. The valve opens 18 degrees before TDC. Subtract 18 from 138. The lobe center is 120 degrees.
An exhaust cam's lobe center is found by subtracting its closing angle after bottom dead center (BDC) from one-half the total duration. The Nighthawk's exhaust cam has a total duration of 276 degrees. Its valve closes 20 degrees after BDC. Subtracting 20 from 138 equals 118; that's the exhaust's lobe center.
To set our Nighthawk's lobe centers where I wanted them, I had to elongate the holes in the cam sprockets in order to change the position of the cams in relation to the crankshaft. The cam sprockets were case-hardened and could only be ground with tiny grinding stones. I used a Dremel tool and stones available from the local hobby shop.
Once the holes were lengthened and the sprockets reinstalled, the cam-timing procedure went rapidly. This job is much easier than it seems. I make a careful guess as to where the cam bolt ought to be in the slotted sprocket and snug it down. Then I check the opening or closing angle of the valve, depending on whether it is an intake or exhaust cam. It usually takes a couple of tries to position the cam within the range I have chosen.
It isn't necessary to recalculate the lobe-center number every time you change the sprocket position. For instance, I calculated the 'Hawk's intake lobe center and learned that it was opening its valves about 15 degrees later than I wanted. I merely added 15 to the actual opening number to get my new desired intake-valve opening angle of 33 degrees.
My first sprocket-positioning guess opened the valve at 33.5 degrees, plenty close enough. I got the exhaust to close its valve at 32 degrees after BDC on the second try. The end result: 104.5 degrees on the intake and 106 on the exhaust, within my goal of 104 to 106 degrees.
Don't let this lobe-center business intimidate you. It is easier to do than to read or talk about. You need a degree wheel. Vance & Hines Racing has one as does S&S Cycle. I prefer the S&S because of its machined steel center and somewhat greater durability.
Although you can use a dial indicator to measure valve openings, you can get equally accurate results by introducing about half a millimeter of valve clearance. The idea is to get past the rather gradual opening ramps that make it difficult to decide just when the valve is really opening. When all the valve clearance is taken up, you read the degree wheel. Continue to turn the crank and take another reading when the valve clearance reappears.
Our Nighthawk ran much better below 7000 rpm with its retimed cams. It is especially good below 5000, where the engine spends most of its running time. It is more responsive and makes more power over a wider rpm range. However, peak power rpm has been lowered slightly. Our Nighthawk now peaks at about 10,000 rpm instead of 11,000.
Since the stock cams have such radical timing, I consider the lobe-center alteration to be an important and unavoidable step in making the Nighthawk engine more suitable to the average American riding style.


INTAKE
Like most recent motorcycles, the Nighthawk has a restrictive intake system. The inlet horn to the airbox limits airflow at high rpm and full throttle. There is power to be had by removing this restriction. The answer isn't as simple as removing the horn or airbox lid. The fuel-air mixture is already achingly lean, and this modification will only make matters worse if it is not accompanied by carburetor recalibration.
K&N Engineering makes a filter and carburetor recalibration kit for the Nighthawk, which includes a large replacement filter and a carb-recalibration kit from the Dynojet company. Dynojet's kit consists of a new set of adjustable needles, two sizes of main jet, a drill bit and a set of instructions. The drill is used to open up the vacuum-sensor hole in the carburetor slides.
The size of the hole in a slide determines how fast the slide raises in reopened sponse to opening the throttle. If the hole is on the small side, the slide raises slowly and keeps the mixture lean. However, if the hole is made too large, the slide raises too rapidly and the mixture will also be too lean. Don't try to second-guess what Dynojet has done; its drill size is not arbitrary.
Dynojet's adjustable needles have a more rapid taper and enrichen the mixture over the stock needles. Neither of the two main-jet sizes were correct for our engine, but that isn't the fault of either Dynojet or K&N. The K&N kit has been calibrated for use with the stock exhaust system, and our SuperTrapp simply needed slightly different jetting. I found that number 125 main jets were correct for the K&N kit and the SuperTrapp exhaust. You can get the jets from your Honda dealer.
The most difficult single task of the entire project was getting the carburetors off and back on the bike. Our machine is a California model with a maze of hoses, valves, hose clips and mounting brackets, all hidden under the tank. When I saw all that for the first time, I remembered why I liked singles.
Even without the emissions-related paraphernalia, the Nighthawk's carbs are difficult to remove. A can of WD-40 helps. I sprayed it on the rubber manifolds and both ends of the carbs to lubricate them. Remove all the metal hose clamps that hold the carbs in place before you pull them out. If you don't, the clamps will likely get bent and scratched. The factory shop manual's instructions were useful, accurate and clear.
Dynojet's kit performs as it should. The specified needle position worked with the SuperTrapp pipe. Our bike only needed the larger 125 main jets and two turns out on the mixture screws instead of the suggested two and a half. This kit vastly improves throttle response, and I strongly recommend it.
Be sure to balance the carburetors after you finish installation of the filter and jetting kit. Even a slight imbalance affects engine smoothness and response at low throttle settings.


EXHAUST
We had several reasons for using a SuperTrapp stainless-steel exhaust system on our Nighthawk. The owner of the bike, Dr. Harry Hurt (yes, that Harry Hurt), preferred the SuperTrapp because of its appearance. SuperTrapp's Nighthawk pipe has a reputation for superior performance. Since we were not going to do time-consuming development work on this engine, it was important that we get as much tunability as possible out of the parts selected. SuperTrapp's variable-restriction muffler design gave us a measure of control that no other system can match. I knew that a certain amount of sound level and engine tuning would be available to me via the variable number of plates that could be fitted to the muffler.
I settled on 10 plates as being a good compromise between peak power output and sound. Initial testing was done with 12 plates, but that configuration was too loud. There was no noticeable loss of power with 10 plates, which is the number I recommend. Eight plates further silence the exhaust note but begin to eat into top-end power.
Even if the exhaust had only matched the stock system in power output, it would have increased our Nighthawk's performance, since there's nearly a 20-pound difference between the two. Certainly, the SuperTrapp gave us a substantial power increase and reduced weight significantly.


THE CHASSIS

TIRES
Nighthawks have 16-inch front wheels, making them more sensitive to the quality of the front tire. The OEM tire at the front wore well but slid before the rear. That, friend, is scary. When close to its limits of traction, the stock tire squirmed and made the steering feel rather vague. It had to go.
We fitted a set of Metzelers. Since we were unhappy with the 'Hawk's front wheel tracking, we wanted a tire that would give us an extra measure of directional stability. Metzeler's Laser front tires are exceptional in that regard. The Laser made an even bigger improvement than I expected.


SUSPENSION
The Nighthawk has one of the finest street suspensions in motorcycling. It gives a superb ride and good control when pushed. There is no harshness in spite of the small front-tire diameter and rather heavy rear-wheel assembly. There are enough adjustments to allow the rider to customize the ride to his or her particular needs. We found only a couple of reasons for altering the stock suspension: wear and weight.
Although the 'Hawk's rear dampers perform well, they have short lives. In 4,000 to 10,000 miles, depending on how hard they are used, they lose a substantial amount of their control, and the rear begins to feel vague. We chose a set of Progressive Suspension's spring and damper assemblies for several reasons.
Progressive Suspension dampers give a smooth ride, and we didn't want to take away any of the day-to-day ride quality of the Nighthawk. Part of the good ride is due to the two-rate springs Progressive uses. The lower rate gives a smooth ride, and the other adds control when riding double or fast on a bumpy road.
If you weigh more than 175 pounds, you might want to install Progressive Suspension's fork springs. Those below 175 will probably be happy with the stock springs. I like the heavier Progressive springs, though Nick, who is lighter and rides faster, prefers the stock ones.
There are two adjustments to fine-tune the fork: you can play with air pressure, or you can add spring preload. An increase in air pressure has its largest effect when the fork is in its last third of travel before bottoming. You should increase fork pressure to limit braking dive or to limit fork travel over severe bumps. I prefer 16 psi for my weight and for the way I ride the Nighthawk.
If you find yourself adding more than 20 pounds of pressure in an effort to raise the front of the bike, you're doing the wrong thing. What you need to do is add spacers under the fork caps to increase spring preload. A .5- to 1-inch set of spacers should give you what you need. If you raise the front with excessive air pressure, the result is a harsh ride during the last half of fork travel.


BRAKES
Stock Nighthawk brakes are powerful, won't fade and have a good feel. However, they can be made more powerful and their feedback improved.
As I always do, I fitted a set of Russell Motorcycle Products brake lines. And, as always, they fit perfectly. The lines improve the feel of the brake. The stiff Teflon tubing that lies under the braided stainless-steel wire cover expands much less under pressure than the stock reinforced rubber hoses. I also installed soft-compound Ferodo pads, another reflex action for me.


MISCELLANEOUS
We fitted a Corbin Gunfighter saddle to our Nighthawk for the same reasons most people might: it looks good and gives the hard charger a better place to sit. The pocket formed by the Corbin seat makes it easier for a rider to move from side to side. The bike's lower center of mass helps too, although long-legged types might find the reduced distance between the Corbin seat and the footpegs a bit cramped.
Every motorcycle should be fitted to its rider. When you bought your Nighthawk, its controls were in a standard position. Chances are that standard setup isn't quite right for you. Experiment with control positions. Raise or lower the brake pedal. Rotate the levers on the handlebar assembly, as well as the bar itself. It won't take much fiddling to get things right. A word of caution: Refer to the shop manual when you make control adjustments. For instance, when you lower the rear-brake pedal on the Nighthawk, you must also check and possibly alter the position of the brake-light switch; otherwise, the brake light might burn all the time.
Go over your bike's controls and put a little oil on things that move against one another. Lube the cables, fuel valve, folding footpegs, control levers and any items that seem to need it. I use WD-40 for cables and Kai-Gard 30/30 for everything else.
If you do a lot of riding at night, install a 55/100-watt bulb. You won't normally need more than 55 watts on low beam, but the 100 sure is nice on dark and empty roads. Custom Chrome, Inc., sells a high-wattage taillight bulb that substantially increases rear visibility.


LAST WORDS
We believe the moderate changes made to our Nighthawk were successful. Our goal was to improve the midrange performance without losing top-end power. While we might have lost some very-high-rpm performance by reducing the cam-lobe centers, any such loss was more than compensated for by the improved breathing that resulted from installing the K&N intake kit and the SuperTrapp exhaust.
Our modified Nighthawk certainly runs better in the rpm range where most of us spend our time. There was a big improvement in throttle response and performance below 5000 rpm, and the bike is much more pleasant to ride through slow traffic. The power surge that used to occur at 9000 rpm now starts at 7000. High-rpm power now ends at a little over 10,000 rpm instead of 11,000. The peak power width is now 3000-rpm wide instead of 2000. The bike is much faster than it was and also much easier to ride at all engine speeds.
All the tuning in the world, though, will not compensate for cubic inches. My ideal Nighthawk would weigh the same as it does but have an engine with twice the displacement. I wouldn't want any more peak power, but it would be nice to have twice as much at 4 grand.
Many of us waited for Honda to introduce the inevitable larger version of the Nighthawk. Instead, it dropped the bike. Too bad. I believe that was a mistake. A larger Nighthawk could be the best UJM ever built. Why it hasn't been built is puzzle.
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Offline Larry Fine

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Re: CB750 page at Wikipedia
« Reply #17 on: August 07, 2017, 04:20:28 PM »
Excellent reading - thank you!  Does any of this apply to the '91-'03 NH-750, or should we be satisfied with the torque and mid-range power they come with?

Offline mollusc

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Re: CB750 page at Wikipedia
« Reply #18 on: August 07, 2017, 09:10:11 PM »
No, this is specific to the 700S.
There is also some debate as to whether or not this altered timing affects the engine in other ways, including early failure.
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Offline hppants

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Re: CB750 page at Wikipedia
« Reply #19 on: August 08, 2017, 06:23:53 AM »
I would agree with the Dragon, the '91-'03 is so reliable, any miniscule differences in power (if there are any, and I don't think there are) are hardly worth debating.  The suspension on the US version of the late model was a bit lacking, but with a set of aftermarket progressive springs, a fork brace, fork oil to match the rider's taste, and a set of progressive shocks, that problem is totally solved.  You could do the washer mod on the slides to address the low throttle lean condition.  There's not much you can do about the drum brake, although it is pretty effective for what it is.

A 12 year run with only color and engine finish changes, even for a Japanese bike, is very telling.  Honda did it right, they slam dunked the marketing strategy, and the price point, and it paid off in spades.

Offline DesertDragon

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Re: CB750 page at Wikipedia
« Reply #20 on: August 08, 2017, 03:05:19 PM »
DesertDragon - the DOHC 1996 you are referring to is the Nighthawk or the F2?  I'm researching the F2 right now -- I'm not familiar with it at all.

mollusc - someone made the point one time that the Nighthawk was in someways a cheaper bike than the 700S -- chain drive instead of shaft, cable activated clutch instead of hydraulic, more plastic, and some other things I can't remember.
I'm thinking the questions are pretty well answered, but - I can usually find enough change to throw in my 2 cents...
Yep - The 96 (actually 91 to 03 imported to the US and Canada in pretty much the same form have the CB750 designation and are NightHawks...
As Mollusc pointed out, the later 'Hawks were a "cheaper" bike. 
Part of Honda'a research and marketing strategy was to build the bike to a price point, specifically $3000 USD.
To do that, they reused some parts and simplified others (like the brakes and clutch).
They were also making it a recognizable grandson of the original CB750, which had many of the same features..

As far as the other discussions around powerband, the latter CB750's actually hit their sweet spot in the power curve at about 5 grand, so you don't really need to alter the cam timing, especially since the bike (IMHO) has relatively low gearing to begin with.

Some of the comparisons aren't really so much better or worse (cheaper or expensive) as they are about preference.
Is shaft drive more expensive than chain drive?  Costs more to manufacture, but is it better?
As with everything, there's a trade off.  Shafts are less efficient for power delivery, but cleaner and require less ongoing maintenance.
They also "feel" different.  Especially for quick power on/power off situations, shafties tend to have more input into the suspension.

So, I guess it depends on what you like or feel is more significant.

Keep the Rubber on the Bottom!

DD

Offline Kevdog3019

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Re: CB750 page at Wikipedia
« Reply #21 on: August 09, 2017, 08:59:54 AM »
My 700s has been dialed up with main and idle jets and K&N filter in box. No flat spots now and very linear. Good from 4K RPM up/no surge on top end to write home about in comparison to weakness down below. It's way too lean stock. It's still not massive down low (don't get me wrong), but it now isn't weak in comparison to up top. Gas mileage only 32mpg. :(

Offline DesertDragon

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Re: CB750 page at Wikipedia
« Reply #22 on: August 09, 2017, 10:02:34 AM »
My 700s has been dialed up with main and idle jets and K&N filter in box. No flat spots now and very linear. Good from 4K RPM up/no surge on top end to write home about in comparison to weakness down below. It's way too lean stock. It's still not massive down low (don't get me wrong), but it now isn't weak in comparison to up top. Gas mileage only 32mpg. :(
WOW - 32 mpg...  Ouch!
My '96 has a 17 tooth front (stock is 15) and stock sized 38 rear sprocket both of which were changed when it was time for a new chain.
At 4 grand on the tach, I'm doing ~ 78 mph and I consistently get  45 mpg doing it.

Besides the better mileage with a taller front, it makes touring at speed a lot more pleasant.
With the stock gearing, the bike always felt like it should have had another gear past 5th.
Not No More.

I'd highly recommend this mod to anyone who does a lot of interstate driving.

The other mod that I think made a big difference in both comfort and economy, was the addition of a Rifle Sport fairing.
Much better aerodynamics, lots of protection and it doesn't add much weight.  i noticed a good bump in fuel economy after the install.
I got both the shorter sport windshield for summer and the taller touring shield for winter.

Keep the rubber on the bottom folks...
 bkr3
DD
Keep the Rubber on the Bottom!

DD

Offline postoak

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Re: CB750 page at Wikipedia
« Reply #23 on: August 09, 2017, 12:39:56 PM »
Yeah, that is quite a change.  My stock Nighthawk did 57 at 4000, 72 at 5000, and 85 at 6000.

Offline mollusc

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Re: CB750 page at Wikipedia
« Reply #24 on: August 09, 2017, 12:54:14 PM »
My stock 700S averages 33mpg overall.  Best ever has been 54mpg on a straight highway run.  32mpg doesn't seem that far out of spec.
made of meat

 

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