These following FAQs have been extracted from cj750.net site with permission. The Chang Jiang 750 is an old technology motorcycle and needs to be appreciated for its age. We have done many things to improve the performance of the Chang Jiang 750, however we have to emphasize that this bike needs to be ridden like a classic motorcycle, thus with care and attention. Please read over this page carefully to better understand the Chang Jiang 750 sicecar. There are some really useful information here.
engine cleaner may actually harm your engine because it can strip
off metal from the engine block, enter pores in the engine and harm
Is synthetic oil good for my engine?
Synthetic oils can dissolve the seals in this type of motor. DO NOT
use synthetic oils.
Is overheating normal?
Depends 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.
Having a well tuned bike (ignition timing, setting your valves, and synchronized carburetors) will seriously reduce the problem of overheating. Too much or too little oil will affect the engine heating. A slight calibration difference in the valves will cause overheating. Carburetors that are set too lean will cause overheating.
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.
Is 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.
When do I need to change my engine oil?
every 3,000 kilometers.
When 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?
Press 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.
Check your oil frequently, this means every time before you ride your Chang Jiang 750. In some Chang Jiang 750’s oil disappears like water.
There 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.
After 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.
The 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.
Make 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 replaced.
If 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. 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).
Technically yes. But, for the Chang Jiang 750 their effectiveness can depend. You will still need to rely heavily on the rear brake to stop.
Regular leaded gas is best, but any unleaded gas will also work.
The 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.
Down 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.
There 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.
There aluminum alloy rims with high strength stainless steel spokes availble. 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. The best wheels with spokes are the M5 wheels. The M5 wheels have aluminum rims and hubs and the spokes are stainless steel.
The 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. Make sure the spokes are all evenly tightened, and always replace broken spokes immediately.
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 bikers that want top speed, we recommend the CV carburetors, 3 ring pistons, high speed 4th gear or high speed rear differential.
On 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. Generally, this is a very worthwhile upgrade for the 24 hp engine.
The difference as like the the 3 ring pistons are very noticable. It has higher compression, less noise, and engine runs cooler importantly goes faster.
strongly recommend the high performance carburetors.
The Fire Dragons where the first to test these carburetors and found that they improve the performance of the CJ750 sidecar incredibly.
Obvious, 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. 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.
Faster top speed. As with the high speed 4th gear, I 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.
The high speed 4th gear is a better value. It cost less. The performance will depend on the type of engine you have.
Theoretically, 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.
No. 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 are the stock transmissions that have a lever that can go into
reverse from first gear.
Different 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.
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.
Yes, 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.
Yes, 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.
It is not possible to install sidecar brakes on left hand buckets.
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 in period.
My 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.
There 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.
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).
There 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.
My 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
My 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
My Chang Jiang 750 does not accelerate out of first gear smoothly?
the Chang Jiang750 jolts a bit on accelerating the clutch throw-out
bearing might be bad.
My Chang Jiang 750 does not decelerate when I down shift and when changing gear the clutch reacts very slow?
likely your clutch actuator might be bad, the bearing may be worn
or clutch might have some problems.
My Chang Jiang 750 does not accelerate well?
Adjust 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 gas mileage.
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. We have plenty of good recommendations about these
My Chang Jiang 750 goes to one side when braking and accelerating?
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.
How 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.
My battery does not charge?
can be a loose ground cable, the alternator, the rectifier, the voltage
regulator or other electrical parts.
My Chang Jiang 750 does not turn on with the key switch?
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.
I 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.
My 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 not start?
My engine is back firing and has irregular sparking?
the condenser, points, spark plugs, spark plug cables and carburetors.
My engine is only firing on one cylinder?
your spark plug, spark plug cables, ignition coil, fuel delivery or
There 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.
There 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.
There is occasional blue smoke coming out of my exhaust pipes?
oil might get into the combustion chamber via the carburetors. Most
Chang Jiang 750 sidecars 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.
There 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.
My bike back fires?
your carburetors, condenser and points.
Handle bars wobbles?
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.
Handlebar wobbles especially when I brake?
be a problem with the forks or wheels. It is possible your bike has
been in an accident.
My 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 cables.
Idle 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.
My Chang Jiang 750 starts but engine is running off beat?
(synch) your carburetors, check the plugs and spark plug cables.
My idle is running a bit fast or too slow?
your timing and carburetor adjustment.
My Chang Jiang 750 runs but has no power?
the following: carburetors, valve adjustment, ignition timing and
My 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
Can I make the brake lights work when I use my front brake?
unless you modify the bike to have a front brake switch installed.
Many European countries require this for their sidecars. This is the
law in most countries in Europe and America.
How 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.
My 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.
My Chang Jiang 750 is having a hard time changing gears and it gets very hot in the transmission area?
that your gear box has not run out of oil.
What type of gear oil should I use?
recommend SAE 80W90
How much oil should I put it the transmission and rear differential?
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 bottom.
My 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.
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.
How 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.
My 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.
My engine runs, goes into gear, but bike does not move?
teeth in the back wheel can be worn out, back wheel might not be tighten
in properly, or drive donut is broken.
I am big and heavy, my seat keeps hitting the fender?
can be adjusted for the seat to be higher or use double springs.
The 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.
I hear a pulsating hissing sound?
head gasket may be leaking, spark plug may be loose, and may also
be the carburetors.
Do 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.
My 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.
Gas 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.
How much throttle should I give my Chang Jiang 750 when starting?
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.
What should I carry besides basic tools?
liter of motor oil
Please note: Be patient and break-in your Chang Jiang 750 properly. Each Chang Jiang 750 has its own personality thus each one feels and rides differently. The person that puts restores your sidecar will also make a difference in how it reliable it is. There are many little details to make it run well. Please learn about your sidecar. These are old technology motorcycles however most riders now to ride twice as fast as they were intended to. Ride slow and enjoy the ride.