Here is a FAQ for the Honda CB750 that i found very useful, even in just rebuilding my CB900F. This FAQ is referenced from the Honda CB750 Riders Yahoo Club. I did not write this personally. Please visit and join the Honda CB750 Riders Yahoo Club For more information. CB750 Frequently Asked Questions (FAQs)
This document contains answers gained by consensus to some of the more
commonly asked questions posted by members of the Yahoo CB-750 Group.
Keep in mind that Honda started production of the CB-750 in 1969 and it
is still in production today. Note that membership in the CB-750 group
is worldwide and your 1995 CB-750 may not be like that of a 1995 from
another country (market). For example the current CB-750 in the United
States is not like the model in Europe, designated SevenFifty. The
SevenFifty has dual brakes in front and a single disc brake in the rear.
Where can I find a good deal on apparel?
You can usually find the best deals on the Internet. Some businesses
do not charge shipping if you purchase a certain amount of goods. In
the United States, most companies do not charge sales tax if you order
over the Internet, but there are exceptions so ask the sales rep. Look
for last years fashions for the best deals. HINT: After you find what
you want, locate a local business that carries the product, and try it
on there before ordering over the Internet. This will assure proper fit
and save you won’t have to return it because of poor fit. You may also
be able to get them to price-match. It doesn’t hurt to ask.
B1
Where can I purchase an inexpensive battery?
In the US, you may find a battery at Sears, Wal-mart, automobile parts
store, or a store that handles riding mowers. Be sure to look up your
bike in the manufacturer’s application catalog. Better yet, take your
battery along to be sure you get the correct one. Observe the physical
size and the position of the battery posts. Bike cables are not very
long and if you get a battery with the posts in the wrong place, it is
unlikely that you can move the cables to make the battery work.
B2
How long should the battery last?
It is rare to get 4 years service from a motorcycle battery for several
reasons. Generally two riding seasons is about it. Be sure to check
the battery fluid often. The liquid in motorcycle batteries seems to
deplete more quickly that in an automobile. Replenish the battery with
distilled water.
B3
Why won’t my motorcycle crank over after I have driven about 20 minutes
and turned it off?
The charging system does not operate until the engine speed is over
about 3,000 RPM (check your shop manual for exact figure). Assuming your
charging system is good health, keep your engine RPM up. This problem
usually occurs when driving around town at slow speeds in too high a
gear, or in lots of stop and go rush hour traffic.
B4
Is it OK to use battery jumper cables to start my motorcycle?
You can usually use battery jumper cables connected to a car’s battery.
However, DO NOT HAVE THE AUTOMOBILE RUNNING or you run the risk of
melting bike wiring.
B5
What kind of charger should I use to charge my battery?
You will need a small charger. Yuasa makes one for motorcycles.
Another one bike dealer’s sell is called the Battery Tender. These can be
left connected to the battery while it is parked and no damage will
occur. Some bikers leave the battery connected to these slow chargers over
the winter so the battery remains charged, which minimizes the risk of
freezing the electrolyte. Car battery chargers generally do not charge
at a low enough rate (below 1 amp) to service a motorcycle battery.
B6
How long do I have to charge a battery that won’t crank the engine?
It is best to charge the battery 24 hours. If the engine still does
not crank over, perhaps the battery is dead.
C1
What is synchronizing carburetors?
Synchronizing carburetors is a process of using a set of vacuum gages,
mercury sticks, or one of the newer style electronic meters to adjust
all four carburetors to the same open position at a specified engine
RPM. These tools measure engine vacuum at the carburetors, usually
through special ports on the carburetors in the case of meters, or at the
carburetor inlet in the case of mercury sticks. The new electronic meters
usually measure vacuum through thin needles stuck into the rubber tubes
between the carburetors and air box.
C2
Why do my carburetors leak gas out the drain tubes?
This situation occurs because the float needle inside the carburetor is
not shutting off the flow of fuel. Most often this happens when a bit
of debris gets lodged between the float needle and seat. On older
bikes the needle may not mate correctly with the seat (its worn out from
age and vibration) to seal off the fuel. Newer bikes have a vacuum shut
off valve between the engine and carburetors, and the gas will not flow
with the engine off. If the carbs leak fuel with the engine off, check
the shut off valve for correct operation. If the carbs leak only with
the engine running, your bike is probably equipped with an automatic
fuel shut off valve.
If you drain the gas from the carburetors into a small cup and notice
debris in the gas, then you can install a small fuel filter in the line
between the fuel tank and shut off valve. These can be purchased at
shops that services lawn mowers. Mount the filter vertically.
Some carburetors have replaceable needles and seats, others do not.
Check with the Honda dealer. There are also aftermarket parts available.
C3
Why won’t my engine idle well or won’t run off idle?
Assuming that the timing is correct, the valves adjusted, and the
engine is getting ignition (spark) this symptom is typically a problem with
the carb’s idle circuit. In many instances this symptom occurs when a
new owner purchases a motorcycle that has been sitting a year or more
with fuel in the gas tank and carbs, which has caused fuel to evaporate
in the idle circuit leaving behind a varnish that restricts fuel flow.
The correction is to overhaul the carburetors, soaking all the METAL
parts for 24 hours in carb cleaner, available at a most auto parts
stores. After soaking, the tiny fuel passages in the carb bodies need to be
cleaned out with compressed air. Never use wire to probe these
passages. Refer to your Shop Manual on the procedure for overhauling,
rebuilding, and setting the preliminary specs.
C4
I bought a bike that has been sitting a long time. What do I need to
do to the carburetors to make the engine run.
See FAQ #C3.
D1
Where do I get a center stand for my bike?
Older CBs came from the factory with a center stands. Honda stopped
putting center stands on bikes some years back. The good news is that
Honda has available a center stand for your bike. For the best price,
shop the Internet.
D2
How hard is it to install a center stand on my bike?
It is easy. In fact, many guys and gals who are not particularly
mechanically inclined have done so. You need just a few wrenches and some
PENNIES. The pennies will be explained later.
NOTE: If you purchase the Honda center stand, be aware that it may
interfere with your bike’s exhaust system IF the system currently on the
bike’s system is not the Genuine Honda exhaust designed for the bike.
Some problems that typically occur are: (1) the center stand will not
swing up fully, which would make it scrape on the ground when maneuvering
curves in the roadway, (2) the center stand has no rubber stop, so when
it is swung up it slams into and dents the exhaust, and (3) the center
stand simply will not fit due to poor engineering on the part of the
custom exhaust manufacturer (this is rarely the case, however.)
Now for the pennies. The center stand is retracted by a powerful
spring. Some folks have a problem stretching this spring to hook it from
the stand to the bike’s frame. Injuries have occurred, such as fingers
pierced by the spring hook, fingers pinched by pliers, etc. Not to
worry! Before installing the spring, while it is in your hands, bend it
one way then the other and while you open up space between the coils,
insert a penny between each turn. This will lengthen the spring so it can
be hooked on to the bike and frame with the stand folded UP. To remove
the pennies, simply lower the stand, which stretches the spring, and
the pennies fall out. Cool!
E1
Why won’t my engine start (run)? It cranks over OK. It was just
running a few minutes ago!
Oh man! I hate when that happens. The #1 problem is the Engine Cutoff
(kill switch as it is affectionately called by some) switch being in
the STOP position. This tricks even seasoned riders. Sometimes, in an
attempt to relax the right hand, the rider will swing his or her thump
forward, and at the same time knock the switch to the STOP position.
Oops! So, the first thing to check is the ENGINE STOP SWITCH. If this
is not the problem, then you need to start normal diagnostic procedures
as described in the Shop Manual.
E2
Why doesn’t my battery charge. I ride around town, and then the engine
won’t crank when I try to start it shortly thereafter.
This may sound odd, but a CBs charging system does not start charging
the battery until the engine RPM reaches between 3,000 and 5,000. This
may sound like a lot of engine speed, but remember, a motorcycle engine
gains its power at higher RPM and an alternator takes a lot of
horsepower to rotate. If the alternator was charging at a lower RPM, the bike
would have reduced power and performance at lower speeds, like around
town.
Assuming the charging system is operating according to spec and the
battery is healthy, the solution is to ride around using the appropriate
gear to keep the engine revolving above the speed that the alternator
begins to charge.
F1
How do I get rust out of my fuel tank?
A gas tank that is constantly being drained and refilled will not have
a problem with rust accumulation. Rust usually occurs when the tank is
sitting for a year or more with no fuel or a low fuel level. In the
case, there may also be sludge and other sediments at the bottom, which
will work their way into your carburetors. This of course, will
necessitate a carb overhaul.
There are several options available to tackle the rust problem. Your
Honda dealer and Internet bike accessory vendors sell a product that
typically goes by the name of ‘creme.’ If you hear of bikers creaming
their tanks, this is what they are talking about. The process usually
involves 2 or 3 steps. The first, an acid bath that removes rust; the
second, a neutralizer for the acid; and third a special coating that
prevents the reformation of rust. This system works well if the tank is not
too badly rusted.
Another option is to take the tank to a commercial shop that does this
sort of thing. Several things to keep in mind here are: The paint job
may be ruined and the tank may have an added plug in the bottom when
you get it back. The plug being added so the coating, which is applied
inside, can be completely drained.
The most drastic situation is having the tank commercially
restructured. This usually involves welding in new pieces of metal. This method
is usually performed on tanks that are completely unavailable in the
aftermarket. We’re talking OLD (antique) bikes in this scenario.
F2
What Octane fuel (petrol, gas) should I use? What Brand fuel (petrol,
gas) should I use?
The best answer is to run the fuel called out in the Owners Manual.
This means on newer bikes in the USA, 87 octane. Older CBs, like the
early 70s models called for 100 octane leaded fuel.
On older bikes, the SOHC models for example, where the specified fuel
is unavailable, try different octane ratings and different BRANDS. You
will discover one that works BEST in your bike with regards to starting
ability, performance, and fuel economy.
F3
What about fuel filters?
The CBs come with a wire or plastic mesh fuel filter screen. In
machines with a manual petcock, such as the SOHC models, the screen is
located inside the petcock and is serviceable be removing the bottom of the
petcock. In machines with a vacuum operated fuel cut off device, a
sock-type filter is located up in the tank at the fuel fitting hose. The
fitting has to be removed and the filter extracted.
These screens are adequate so far as Honda engineers are concerned.
However, if you have an older bike with a tank rust problem, you may want
to consider installing an in-line fuel filter, which will capture very
fine, almost powdery rust particles. Clear or translucent filters are
available at small engine (lawn mower and tiller) repair shops. Ride
your bike over when you pick one up so you get one with the correct
diameter fittings. Older Hondas have 5mm Inside Diameter hose.
To install, simply cut the fuel line somewhere between the fuel tank
and cut off valve. You will need to mount the filter VERTICALLY,
observing any markings on the filter than indicate inlet and outlet. On the
SOHC models with two fuel lines off the petcock you will need two
filters.
G1
Which helmet is the best?
We are not even going there! Helmet styles are a personal preference.
Try as many on as you can, then decide which is best for you.
There are several important considerations. First, in the U.S.A., in
States that require riders to wear a helmet, the helmet must pass U.S.
Department of Transportation standards. Helmets that pass this spec are
emblazoned with a DOT sticker. The second consideration is the Snell
Foundation safety standard. It is purported that the Snell standard is
tougher than the DOT standard. Some helmets have both the DOT and
Snell ratings, others have one or the other. Just remember, if your state
has a helmet law, the helmet must have a DOT sticker on the back.
Keep in mind that all helmets that wear the DOT label meet minimum
requirements for peripheral vision among other things.
H1
Where can I get an Owners Manual?
Check with the Honda dealer first. He may have them is stock. If not,
you will have to order one. Provided your bike is not vintage, you can
probably still purchase one from Helm, Inc., the leading distributor of
automotive manuals. Search ‘helm incorporated’ on the Internet. You
can also check on EBay.
J1
Where can I find parts for my bike. Honda no longer makes them.
Regardless if Honda still makes them or not, the CB750 is quite popular
and parts are available through a number of sources. Do some
sleuthing. Besides your local Honda dealer, look up other Honda dealers around
the country and either e-mail them or call them for what you need.
Check for local motorcycle salvage yards; peruse the on-line auction
houses, such as EBay; search the Internet for motorcycle accessory stores;
talk with other bikers; and use this Yahoo group. A British company,
www.davidsilverspares.com, makes some replica body parts and seats and
has millions of pounds worth of ‘new old stock’ (NOS) parts gleaned from
around the world.
J2
The dealer charges too much. Where can I find parts for less.
The Internet is your best source. Moto America offers Genuine Original
Equipment Honda replacement
parts at US Dealer Net + 10% to members of this group. This applies to
all currently available US Honda part numbers. For a quote write to
Brian Rosencrantz at motoam@aol.com.
However, remember the local guy is your NEIGHBOR. You can gain a
wealth of knowledge and information by becoming familiar with the owner,
parts department personnel, and service personnel. Besides being able to
tap their brains for information that could save you big bucks in
service, they also make good riding companions. The dealer may even sponsor
a club.
Honda engineered Honda parts to fit Honda motorcycles. Generally,
unless you are racing, GENUINE Honda parts will give you the best service
on your bike for price, fit, and function.
Now here is a benefit of getting to know the local dealer. His prices
may be higher than what you can find at Honda dealers that operate
dot-com outlets, but over time, he may be willing to give you a discount on
parts if you are a regular. This could be beneficial in regards to
time, ease or returning something that was not needed, savings on shipping
returned items, elimination of getting the wrong part (look at it
before you take it home), etc.
HELPFUL HINT: Check the price of a given item at several dealers in
your area. Sometimes one will have a better price.
K1
What is the best shop manual for my CB? Where can I get a Repair
manual for my CB?
Two aftermarket manuals are currently available for the SOHC models:
(1) Clymer “Honda CB750 SOHC Fours 1969-1978 Repair Manual,” which
includes data for the K, F, and C models; and (2) Haynes “Honda CB750
1969-1979 Repair Manual.” For detail, most group members would prefer the
Clymer manual over the Haynes manual.
For the CB 750 Night Hawk (DOHC) order the Honda Repair Manual from
Helm, Inc. or the Clymer Manual for your Honda’s year range.
The Honda “Common Service Manual,” spells out general repair procedures
for all motorcycles and is designed for use in conjunction with
cycle-specific manuals.
Where available, the factory manuals are preferred. However, the
others adequately detail how to accomplish any repair. All the manuals
detail service, repair, and maintenance procedures. The manuals also
include wiring diagrams and call out specialty tools needed to perform
certain repairs.
Another interesting consideration for these manuals is they provide
good photographs of what the bikes look like from the factory. This
information is of great value to motorcycle restorers who need to know where
warning placards were placed, how hoses were routed, what decals were
present, the correct wiring, which may have been altered over the years,
etc.
Check Amazon.com or Ebay.com for good values on new and used manuals.
