and Performance for CJ750:
basic maintenance and performance tips are what
we get from people that are very experienced Chang
Jiang 750 sidecar owners. They may not be the
most detailed answers, but we do hope they give
you a good idea of what may be the solution to
all of your Chang Jiang 750 questions. Also, they
should help keep your Chang Jiang 750 in top running
welcome your input. Please feel free to send us
any additional CHANG JIANG 750 tips you have,
so that we may post it and help out other Chang
Jiang 750 owners.
“the Chang Jiang 750 is a high maintenance
motorcycle”. This is 1930s technology and
should be treated as such. If you live in China,
then you are lucky to have plenty of Chang Jiang
750 mechanics around that can help you out. The
cost is generally just a few dollars. Most Chang
Jiang 750 shops in China will even do minor repairs
for free if you bought your bike from them. Leaking
oil is probably the biggest concern compared to
modern motorcycles. Being that these motorcycles
come from a “simpler” era, they are
not real complicated. You will not find many electronic
black boxes on them, they are mostly steel and
rubber and very basic machines. Some mechanics
say that if you can tinker with a lawn mower,
you can basically do work on a Chang Jiang 750.
“If you live in a western country make sure
you are comfortable with a wrench before buying
a Chang Jiang 750 “
engine gas cleaners and solvents good for my engine?
engine cleaner may actually harm your engine because
it can strip off metal from the engine block,
enter pores in the engine and harm engine internals.
synthetic oil good for my engine?
Synthetic oils can dissolve the seals in this
type of motor. DO NOT use synthetic oils.
on the road conditions and how your ride your
bike and also what you consider as overheating.
It is normal for the CJ750 may run very hot especially
the smaller engine.
a well tuned bike (ignition timing, setting your
valves, and synchronized carburetors) will seriously
reduce the problem of overheating. Even too much
or too little oil will affect the engine heating.
the Chang Jiang 750 should not overheat unless
going uphill for long distances. It is normal
practice when we ride in the summer to rest the
Chang Jiang sidevalve 24 HP engine every hour
or 50km on mountain roads or every 45 minutes
of riding to let the engines cool down.
it bad to spray water on my engine when it is
hot to cool it down?
too much cold water on your engine can crack it
if it is too hot. Importantly cooling it too fast
will cause the outside engine case to contract
while the pistons and parts inside the engine
is still expanded from the heat, thus this may
cause scratching of the piston walls. Best to
take a 15 to 20 min break and let it cool down
naturally. Chang Jiang 750 sidecars are not meant
for fast speeds and to be stressed for extended
periods. Relax and enjoy your ride, and take an
occasional stop to rest the engine. The same rule
applies when crossing a river or deep water; let
your engine cool down.
do I need to change my engine oil?
every 3,000 kilometers.
should I check my engine and transmission oil?
check is a good rule of thumb. Definitely every
time you fill your gas tank, check the engine
oil. Most Chang Jiang engines do leak and burn
oil so a few drops of oil on the garage floor
is normal. Basically it is best to check the engine
oil as often as possible. For transmission oil,
we recommend every 1,000KM.
oil leaks common?
Yes, the Chang Jiang 750 tends to leak some oil
(just like a Harley), however it should not be
too much (usually just a few drops). Be aware
of oil leak at the rear main seal. If this happens
oil can wet the clutch plates, causing the clutch
can I see the oil on the oil stick especially
when I use new oil?
your oil stick on a clean cloth and look at the
oil mark on the cloth. You may machine the dip
stick by grinding it flat on one side or use a
tap and die and cut thread into the bottom of
the dip stick. This will make it easier to read
the oil level. Keep your oil near the top line.
NEVER over fill the oil.
your oil frequently, this means every time before
you ride your Chang Jiang 750. In some Chang Jiang
750’s oil disappears like water.
the type of head gasket used on the Chang Jiang
750 engine affect my bike?
are 2 types of head gaskets, one is a thin solid
copper gasket. This is sometimes preferred because
it is a better conductor of heat from the cylinders
out to the heads where there is more cooling.
The other type of gasket has asbestos sandwiched
between 2 thin plates of copper. If the machining
of the head and cylinders is not exact, the asbestos
will fill in any imperfections. You can take the
copper asbesto gasket apart and just use the copper.
just put in new gasket?
100km or so, check and re-torque the head bolts
if necessary. Sometimes the head bolts loosen
due to the heat and vibration, especially after
it is first installed. Remember to torque the
head properly going from opposite sides of the
head and torque them gradually. Never take the
head cover off when it is hot.
there ways to improve the brakes?
Chang Jiang 750 is a very heavy motorcycle, and
does not stop like a high performance motorcycle.
It depends mainly on rear wheel braking. There
are a few types of brake shoes and also there
are two types of thickness for the brake shoes.
The softer brake shoes control feel much more
sensitive however the harder type last longer.
sure that the pads are put in correctly and correct
side on the inside. Make sure your brake drum
is not old and worn, if so, it may need to be
you drive at 60 KPH (40 MPH) you will likely be
fine with the stock brakes. Many Chang Jiang 750
riders do end up modifying their bikes to improve
brake performance. Big Bill's Bikes offers sidecar wheel brakes,
hydraulic front disk brakes and M-5 drum brakes
which all will greatly improve your Chang Jiang
750 braking. (the M-5 drum brakes use wider brake
shoes and stop much better).
disk brakes better?
yes. But, for the Chang Jiang 750 their effectiveness
can depend. The Chang Jiang 750 is a very heavy
bike, so disk brakes in the front will not make
a major difference. You will still need to rely
heavily on the rear brake to stop.
disadvantage of having a hydraulic front disk
brake is that if get a flat tire, the 4th (spare)
wheel will usually not a disk brake on it. Make
sure that you get a proper installation and you
will be able to rotate all 4 wheels using the
same disk brake. Some Chang Jiang 750 bikers that
have disk brakes have told us that the difference
is only slightly noticeable.
type of gas should I use?
leaded gas is best, but any unleaded gas will
round tires or flat ones better?
Chang Jiang 750 sidecars do not lean on turns
so flat tires are better and more economical.
Solo Chang Jiang 750 should use round (radial
tires) for better performance. It is advisable
to not use off-road tires on the road due to their
reduced traction on pavement.
there differences in tires?
Yes, wear, traction, width and price. Big Bill's Bikes tire
prices range from 80rmb to 250rmb. Tires on a
Chang Jiang 750 tends to wear out quicker because
of the toe-in pitch of the bike with the sidecar.
Some tires wear out faster than others, most of
the better quality newer made tires on the back
wheel will last around 5,000 km.
alloy wheels better than spokes?
side of alloy wheels is they have a harder ride,
and are harder on wheel bearings. Up side of alloy
rims, is they are far truer than the average spoked
Chang Jiang 750 wheel. Spokes have a softer ride,
however on strong impacts the spokes may absorb
the impact, and then the spokes break.
are about 5 different types of alloys wheels available.
For long distance rides, on rough roads, most
of us will prefer to use alloy wheels especially
on the rear wheel.
Big Bill's Bikes
has also aluminum alloy rims with high strength
spokes. These wheels are powder coated and also
may be polished for a super shine. The disadvantage
of the alloy rims are that they are too stiff
and will rip the spokes out of the hub when you
ride on rough roads. For flat roads they are perfect.
Are old stock wheels better than the new ones?
newer wheels are made of thinner metal and you
can see where it is welded together, the spokes
are also thinner and in our experience not as
strong as the older wheels. There are some older
non-polished rims that are made from thicker metal,
however we have seen many that are not true. Big Bill's Bikes
has Duxin spokes which are thicker, however these
can be very difficult to find and in short supply.
Make sure the spokes are all evenly tightened,
and always replace broken spokes immediately.
is the top speed of a Chang Jiang 750?
is a good question. It usually boils down to 1.)
who tuned your bike and 2.) the modifications
that have been done to it. We have Chang Jiang
750 sidecars with 32 hp engines that have done
up to 140 km/h. The new CV carbs are a big help
in the power department. With a normal 32 hp the
Chang Jiang 750 can comfortably cruise at 80 km/h
with top speed of about 110km/h.
For 24hp Chang Jiang 750 sidecars with 24 hp engines
we have seen ones that can reach and maintain
top speeds of 128 km/h. Normally a 24 hp Chang
Jiang 750 can cruise comfortably at 70km/h, with
top speed at about 100 km/h.
bikers that want top speed, we recommend the CV
carburetors, 3 ring pistons, high speed 4th gear
or high speed rear differential.
is the performance of the new 3 ring pistons?
24 hp engines it is very noticeable performance
upgrade. It is not so noticeable on the 32 hp
OHV engines. On the 24 hp engine, when installed,
you notice an immediate increase in acceleration,
gear changing is done at higher engine speeds,
and the engine runs cooler and quieter. The overall
performance will also depend on the quality of
your engine. Big Bill's Bikes has installed over 100 pairs
of them and the performance varied on each Chang
Jiang 750 depending on condition of the engine.
Generally, this is a very worthwhile upgrade for
the 24 hp engine.
is the performance of the new thinner piston ring
difference as like the the 3 ring pistons are
very noticable. It has higher compression, less
noise, and engine runs cooler importantly goes
is the performance of the high performance carburetors?
strongly recommend the high performance carburetors.
Faster and smoother acceleration
Better throttle response
More consistency and balance
No vapor lock, or boiling gas
Engine runs cooler
Better gas mileage
Less gas leakage and sticking floats
Big Bill's Bikes was the first shop in Beijing that tested
the CV carburetor. We tested these, along with
the Fire Dragons M/C Club, for three months before
they were sold on the local market. Big Bill's Bikes has installed
over 100 sets in the past couple of months. Ask
any rider that has them installed, and they will
tell you how well they perform. A very reasonable
price (55 USD) for much improved power and performance.
is the high speed 4th gear performance?
it will be faster, however you need the horsepower
to attain higher speeds. Power on up-hills at
speed in 4th gear is also compromised. This upgrade
is recommended only on the 32 hp OHV engines.
Big Bill's Bikes installed the high speed 4th gear as standard
for premium restorations. Most of the local Beijing
riders use 24 hp engines, on the weekend rides
into the mountains there have been complaints
of not enough hauling power with the high speed
4th gear when going up hills.
is the high speed rear differential ?
top speed. As with the high speed 4th gear, Big Bill's Bikes
only recommends them only on the 32 hp OHV engines.
The 24 hp engine just does not have the power
to push this higher gear ration especially when
there are two passengers.
speed rear differentials versus high speed 4th
high speed 4th gear is a better value. It cost
less. The performance will depend on the type
of engine you have.
a deep oil sump make a difference?
yes. But, experience has shown that it has not
made a big difference. A big drawback of the deep
sump oil pan, is it reduces the CJ750 ground clearance.
Off-road, this can be very detrimental; it is
east to damage the deep oil sump. When buying
the deep sump, make sure that the shop knows how
to modify the oil pump so that it can draw the
oil from lower in the sump, than the stock oil
pump. All the oil will not be circulated if you
do not lower the oil pump suction point. Many
shops will gladly install the deep sump, and not
make any change to the oil pump.
Chang Jiang 750 transmissions without reverse
Transmissions without the reverse gear are simpler.
However, most riders do like the convenience of
the reverse gear. For example, when pulling out
of a “head first” parking space, or
when making a 3 point turn.
there different reverse gear transmissions?
There are the stock transmissions that have a
lever that can go into reverse from first gear.
The “331 tranny” (by Nan Fang) requires
first being in neutral, before switching into
reverse. It takes some getting used to before
being able to go quickly into neutral.
The “52 tranny” (by Chang Jiang) is
the single lever reverse transmission that can
go into reverse in first gear. It is the stock
transmission that is on most Chang Jiang 750 sidecars.
Some riders do not like this transmission because
it is very easy to throw it into reverse when
the bike is moving and grind the gears. This happens
quite often with beginners.
there any differences in the reverse gears boxes?
folks, different strokes, some prefer the M-5
model as it is safer and will not accidentally
grind the transmission. Others prefer the stock
one due to the ease of not having to find neutral
to get reverse.
maintenance free batteries better?
Normal lead acid batteries last longer. Maintenance
free batteries, just like normal batteries, do
vent acid fumes when it they get hot. Sealed “maintenance
free” batteries tend to stay cleaner. If
you have it on the side of the Chang Jiang 750,
it seems more resistant to the elements. If your
battery is on the side of the bike, make sure
it is tied. Batteries have been known to fall
out, when not tied down.
the battery be put in the trunk?
most of our customized Chang Jiang 750 sidecars
have their batteries put in the trunk. But, remember,
if it is the trunk, the biker can not be converted
to a “Chang Jiang 750 Solo” ride,
without switching the battery back to the motorcycle.
Also, be sure that it is in an enclosed box that
is ventilated. We have seen poorly installed batteries
in the sidecar bucket that have let to fires when
metal touched both terminals of the battery. If
your batteries are on the side of your Chang Jiang
750, please make sure it is secured in place.
We have seen batteries fly off during rough rides.
sidecar brakes work?
they work, however they need to be adjusted frequently
due to cables being stretched. It is best to adjust
the cables so that it assist in the stopping and
do not adversely affect the performance of the
bike. We recommend not tightening it too tightly,
as changes in the weight of the sidecar will affect
its performance of the pull of the bike when stopping.
straight pipes bad for my engine?
straight pipes do not give the engine enough back
compression pressure. This can cause extra heat
and stress on the top end of the engine (piston
and valves). You may install straight pipes that
have mufflers in them. It is advisable not to
ride your Chang Jiang 750 with straight pipes
that have no mufflers especially during the breaking
wheels keep hitting the center stand causing it
hit the ground?
the stand can get out of position, and it can
be widened. Also check the spacer / washer in
the rear wheel. It is possible that your wheel
bearings have an excess of play.
is a strong clicking nose in the engine?
small amount of clicking is quite normal however
it can also be a sign of a problem. Excess noise
can be your valves, pistons, etc. 32 hp engines
have overhead valves, with more moving parts,
it has more engine noise than a 24 hp engines.
When the engine starts to overheat, it makes clicking
noises. Also, when overheating, it is fairly clear,
just sitting on the motorcycle. You can feel it.
A lot of Chang Jiang 750 riders have devised different
methods of installing temperature gauges on their
Chang Jiang 750s.
you are overheating, take a rest, and let the
engine cool down. You will feel the difference,
the engine runs far stronger after it cools down,
(and the clicking noise should go away).
is a chirping noise in the engine?
there is a chirping noise and you engine seems
to be losing power, it can be either the gasket
is burnt and leaking or your valves are leaking.
Be careful of leaking gaskets that are facing
your feet. The hot air leaking out will burn your
shoes or pants.
Chang Jiang 750 feels sluggish?
your tire air pressure, and make sure brakes are
returning to position, and that the foot rest
is not pushing down on the brake pedal. Do not
ride your Chang Jiang 750 with flat tires, the
rubber on the sidewalls of the tire will be ruined
and the tube will not stay in place when inflated.
steering is very heavy?
your tire air pressure, and also do not over tighten
the steering damper, make sure the brake is returning
back to position, and not stuck.
Chang Jiang 750 does not accelerate out of first
the Chang Jiang750 jolts a bit on accelerating
the clutch throw-out bearing might be bad.
Chang Jiang 750 does not decelerate when I down
shift and when changing gear the clutch reacts
likely your clutch actuator might be bad, the
bearing may be worn or clutch might have some
Chang Jiang 750 does not accelerate well?
your valves, check the ignition timing, carburetors
may be dirty or may need balancing, clutch may
be worn, etc. The Chang Jiang 750 is a peculiar
motorcycle; the timing may be fine tuned for power
on acceleration, or tuned for high speeds, however
not for both. The timing will also affect the
you like power and acceleration and have a 24hp
engine, try the new 3 ring pistons from Dong Tian.
However be aware of the older 3 ring pistons that
are of inferior quality due to poor controls on
metallurgy as it may wear out your piston walls.
If you have a 32 hp engine, try the new 30mm high
performance carburetors also from Dong Tian. You
will notice immediate improvements in performance,
throttle response and acceleration. Both Dong
Tian products are also available at Big Bill's Bikes. To date
Big Bill's Bikes has installed over 100 sets of the new carbs
and new pistons. We have plenty of good recommendations
about these parts.
My Chang Jiang 750 goes to one side when braking
or “toe in“ of the bike may not be
correct. Different production runs of Chang Jiang
750 sidecars will vary on the camber they have
the sidecar set at. Some Chang Jiang 750s are
a bit taller and the sidecar is lower, others
may have a higher sidecar. We have also seen many
Chang Jiang 750 with slight alignment problems
with the sidecar wheel, most likely caused by
the sidecar hitting the curb too often. A small
amount of pull on acceleration and deceleration
is normal. Also riding with a passenger in the
sidecar will also affect the pull of the bike.
do I know when my bike is not charging?
light on the left side of the ignition key stays
on. If it blinks a bit when you increase above
idle RPM, most likely it is a wiring problem,
if it stays on and nothing happens when you increase
the RPMs the alternator may be bad. If you are
riding fast, leave your head lights on. At night
when riding in the city with the lights on, your
Chang Jiang 750 may not charge fast enough, the
rate of usage can exceed the charging rate of
the system. This may result in the battery running
out of power.
battery does not charge?
can be a loose ground cable, the alternator, the
rectifier, the voltage regulator or other electrical
Chang Jiang 750 does not turn on with the key
the switch or fuse under the seat or in the electric
box. Run a wire from the positive terminal of
the battery to the positive wire on the 2 way
coil. You can now kick start your bike.
push my starter button and nothing happens or
starter turns very slow?
nothing happens electric might be bad or the switch
might be broken, if starter turns but very slowly,
it could be a weak battery or bad starter. Some
starters just get worn out and will have no power.
starter turns and engine does not start?
your distributor, points, gas, plugs, spark plug
cable, or the starter gears might be worn out.
starter and engine turns but Chang Jiang 750 does
Make sure the gas is on and you have gas, and
tickle the button on the top of the carbs a few
times. Check the spark plug cables to see if there
is spark. Open the distributor and see if the
points are sparking. If there is no electricity
going to the cables it may be a bad coil. If the
points are not sparking it may be the distributor
engine is back firing and has irregular sparking?
the condenser, points, spark plugs, spark plug
cables and carburetors.
engine is only firing on one cylinder?
your spark plug, spark plug cables, ignition coil,
fuel delivery or carburetors.
is white smoke coming out of the exhaust pipes?
is water in the engine which may be from the engine
being cold, or improperly adjusted carburetor.
is blue smoke coming out of the exhaust pipes?
are burning oil. It may be from worn valves, or
a problem with your piston or rings. It also could
be a scratched cylinder wall.
is occasional blue smoke coming out of my exhaust
oil might get into the combustion chamber via
the carburetors. Most Chang Jiang 750s have a
oil vent line (hose) goes from the front of the
engine block, into the air filter housing. The
air filter can fill and overflow.
is some rattling sound from the exhaust pipes?
innards of the muffler can come loose. Also make
sure the bolts that hold the fender mounts are
tight. Vibration loosens most bolts with time.
Installing lock washers on every nut on the bike
is a good idea.
bike back fires?
your carburetors, condenser and points.
the steering damper. That is the butterfly knob
in front of the handle bar. A slight wobble is
very common at low speeds. The front bearing and
fork mount assembly may have to be tightened or
bearings might need to be replaced.
wobbles especially when I brake?
be a problem with the forks or wheels. It is possible
your bike has been in an accident.
throttle is too tight?
the screw under the throttle, oil the throttle,
make sure the cables are moving in and out freely.
Get a cable lubricator, and spray lube into all
does not go down?
that the throttle cables are not sticking. Also,
may be that the carbs may need cleaning. Sometimes
the cable will get caught, hangs up. It this happens
when you are riding, you might have to manually
pull it back down, to allow it to get back into
place. Just pull the cable on top of the carburetor
a few times softly or wiggle it a bit and it should
go back into place.
Chang Jiang 750 starts but engine is running off
(synch) your carburetors, check the plugs and
spark plug cables.
idle is running a bit fast or too slow?
your timing and carburetor adjustment.
Chang Jiang 750 runs but has no power?
the following: carburetors, valve adjustment,
ignition timing and compression.
back brake no longer effective?
your brakes by adjusting the butterfly bolt behind
the brake pedal. The brake shoes may be worn out,
or the drum. Also, rear differentials have been
known to leak, this may cause the brake pads to
get contaminated with oil.
I make the brake lights work when I use my front
unless you modify the bike to have a front brake
switch installed. Big Bill's Bikes installs those on Chang
Jiang 750 going to Europe. This is the law in
most countries in Europe and America.
do I know when my wheel bearings are bad?
may scratch and make a nasty “metal on metal”
noise. Also you may hear some grinding noise and
vibration. Normally bearings may go bad after
a hard impact.
engine runs, drive shaft rotates but the Chang
Jiang 750 does not move?
gear in the rear wheel may be worn out. Rear differential
may be worn out, or the spacer in the back wheel
is broken thus drive is not catching.
Chang Jiang 750 is having a hard time changing
gears and it gets very hot in the transmission
that your gear box has not run out of oil.
type of gear oil should I use?
recommend SAE 80W90
much oil should I put it the transmission and
liters in the tranny, 0.3 liters in the rear differential.
Look carefully when filling transmission with
oil, when it reaches the third thread from the
back wheel drive is leaking oil?
is bad, or it may be too much oil in the rear
drive. A hard impact to the back wheel may also
loosen the seal causing it to leak.
Is slipping out of gear normal on a Chang
on most Chang Jiang 750 sidecar motorcycles the
bike will occasionally slip out of gear. However
it should not happen constantly. The transmission
has two adjustment screws that should cure this
problem. Beware though if you take your bike to
a repair shop. They may charge you for repairing
the tranny, when it only needed an adjustment
of the two screws to fix the gear slipping. When
the bike is moving and the gear slips into neutral
always up shift the gear to get it back into gear.
do I adjust my gears when they are slipping?
upper screw is for adjustment of down shifting.
The lower screw is for adjustments of up shifting.
It is advisable to have a professional adjust
it because they will be able to tell if it is
correct by the amount of movement in the hand
shift. If you have to adjust it yourself, do not
over adjust the screws. Each adjustment should
only be about a quarter of a turn or less. Read
more on our gear adjustment FAQ.
back wheel locked up?
be transmission gears jammed or locked. It could
be the rear wheel differential locked up. It can
be gears jammed from teeth breaking off the gears.
engine runs, goes into gear, but bike does not
teeth in the back wheel can be worn out, back
wheel might not be tighten in properly, or drive
donut is broken.
am big and heavy, my seat keeps hitting the fender?
can be adjusted for the seat to be higher or use
seat is a bit uncomfortable especially the raised
front part is there any solution?
called ball breakers, use a leather seat cover
and pad it with foam or a towel.
hear a pulsating hissing sound?
head gasket may be leaking, spark plug may be
loose, and may also be the carburetors.
I need to turn off the gas petcock?
especially if you are going to let the bike sit
for a while (more than a few days). Best to always
turn it off as it is easy for carburetors to leak
gas. Gas may seep into the engine.
carburetor is leaking gas?
is very common with old stylecarbs. Sometimes
the floats stick, do not rise and shut off the
fuel flow. Press the gas release button on top
of the carburetor a few times, it may free the
sticking float. If it still leaks, take off top
of the carb and clean out the float bowl. Also,
check the float to see if it is cracked or broken.
Sometimes just tapping on the side of the carburetor
with the handle of a screwdriver is enough to
settle the float. Also sharpening the pin that
points out the the float will help it.
leaks out of the top of my tank?
a splash guard in, that is a round screen that
fits into the mouth of the gas tank.
much throttle should I give my Chang Jiang 750
not open the throttle when cranking the bike over.
Let the bike idle and give it time to warm up
too fast; just use a little slow twist to get
the engine started.
should I carry besides basic tools?
liter of motor oil
2 meter long electrical wire to hotwire the bike
in case of electrical problems
Spare engine gaskets
Funnel or plastic bottle for adding oil to the
Spare condenser and points
Spare clutch cable and brake cable
A empty plastic bottle in case you run out of
A last, but sad one: My Chang Jiang 750 was stolen?
hope it’s a legally registered CJ. It’s
always advisable to lock your CJ750, and chain
it to something, especially in Beijing. CJ750
sidecars are often stolen, and if you are lucky
you may get if back. Theft of license plates is
also very common (especially black plates). If
you have all the documents to prove that the bike
is legal, you can get a report from the police
which will allow you to replace the bike with
the same plates. Thus you will not need to buy
a fully registered bike, but an NOS or something
much cheaper and get your original plates replaced
on it. It takes a bit of documentation and running
around but can be done.
Where can I get technical information on my Chang
special "Thanks" to some of the guys
for helping with the information and editing.