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Chang Jiang Motorcycle FAQ

DO YOU HAVE TO PERFORM HIGH MAINTENANCE ON A CJ MOTORCYCLE ?
Yes you have to perform maintenance on a CJ motorcycle. But it does not mean High Maintenance. For some it will look like high maintenance, but for anyone that knows that the CJ is based on a 1938 technology this maintenance will just be the minimum to perform to make the bike reliable.
There are 2 things that make the CJ a reliable bike : MAINTENANCE AND PROPER RIDING WAY.
maintenance on a CJ motorcycle can be performed by anyone with basic mechanical skills and if you do not have any skills, LRM often gives advices and help for anyone with maintenance and/or mechanical issues with his CJ motorcycle. If you want to own a CJ motorcycle you have to be ready to get your hands dirty and also be ready for tinkering. This is one of the part of owning a CJ motorcycle.
The CJ motorcycle brings you back to the early day of biking when you had to be able to fix your bike beside riding it. And this is an enjoyable aspect of biking.
 
WE OFTEN SEE THE FOLLOWING QUESTION : "HOW FAST CAN A CJ MOTORCYCLE GO ?"
The answer is : CJ motorcycles are not made for speed. The speed factor does not apply for bikes made to cruise and not to race. It is not advisable to go fast on a CJ motorcycle as these are not designed for. They braking system is not suitable for high speed such as their general design.
Even if your engine can reach speed of 60 mp/h and up it is not a good thing to do as it will shorten the life of the engine and its component.
If you are looking for a fast bike, then turn yourself to the Japanese bikes o other racing bikes.
 
ARE THE OLD CHANG JIANG MOTORCYCLE BETTER THAN THE NEWER ONES ?
Yes they are and for the following reasons : At the origin, the Chang Jiang motorcycles were produced for the military (People's Liberation Army a.k.a PLA). It was at a time when China did not have money and needed to mechanized their army. So they build bikes that were made to last. They did not have the money to afford fixing a bike every week and they could not afford to change them every year. So they made them to last and to be reliable for their needs. The CJ fitted their needs : simple design to operate, maintain and produced. And also well designed for the poor conditions of the Chinese roads at the time.
The bikes were produced with Mil Spec as every other vehicle built for an army.
Then after the opening of China and the reform the production went for civilian use during the mid 80's. That is when we can say that the quality dropped. The military would still keep their mil spec but at this time the PLA issue bikes were not available for the public.
Then the demand for these bikes decreased with the time, production cost could not be anymore covered by the sale. Tooling, casts and jigs were worn, so to cut the cost the factory started getting parts from private factories where quality control was not what it use to be in the old time.
The drop in the quality in the parts can be easily seen. If you get parts made for the military and late Chang Jiang parts it is easy to see the differences. Some examples are shown here :
The few examples shown in these pictures speak for themselves. It does not take someone too much to see what are the differences.
Based on these facts and after seeing so many bikes we can say that old bikes were better made than the new ones.

ARE OLD PARTS AND BIKES EASY TO FIND ?
Let's start with the bikes first. Complete Chang Jiang motorcycles and/or correctly restored ones from the early production and the 60's are not easy to find. They are rare. You can find some of these bikes but most of the time the components have been changed. i.e : you find a bike from the 60's, the bike's frame is correct fo the period but the sidecar frame as been changed and/or the engine or the tyranny too.
So if you find one of these bikes and you want to have it restored like it use to be when it was build, all with the parts from the period, it is a difficult task.
We have actually restored 2 of these bikes at LRM. One is in China and the other one in LA, USA.
These 2 bikes are collectors items. We actually have only seen these 2 bikes that have been completely restored to the smaller details as they use to be when produced 40 years ago.
Note that you can find many M72 that are the Russian bikes that the Chinese used to build the CJ's.
But fully restored CJ from the 60's, we have only seen the ones we have restored.
These bikes are even harder to find than the BMW R71( less than 4000 produced) and the Harley Davidson XA ( less than 1200 produced). These bikes can be seen here :
 
Now regarding the old parts :
Some are easy to find, some not. The average tell us that you have to look around and spend times to get the older parts. LRM prefers using old parts as they are better made and of better quality (mil spec).
By using N.O.S (New Old Stock a.k.a old parts) parts LRM ensures a certain quality in their bikes and good performances when the motorcycle is ridden.
A very important point : ARMY GREEN DOES NOT MEAN OLD PARTS. IT IS NOT ALL THE PARTS THAT ARE PAINTED IN ARMY GREEN THAT ARE OLD AND/OR MADE ACCORDING TO THE MIL SPEC.
 
WHAT ABOUT CHROMED PARTS AND POLISHED ENGINE ?
The last past years have seen the CJ motorcycles getting customed. Beside other modifications, the use of chrome became a standard in the CJ custom process : with a lot of chrome parts and a polished engine, the bike sure looks good and attractive. A piece of art that will catch anyone's eyes ! You don't even want to ride it !
For a while chrome was a problem as the quality was not so good and they'll rust quickly. They needed "high maintenance" to keep their shine. Now the problem has been solved with the use of better chroming factories. But you still have to remember that you need to take good care of the chrome.
We would not advise the use of chrome for some items like the seats' springs : because of the chroming process, they can brake and/or loose their strength.
Also the as a military vehicle at the origin, some parts are pretty rough and to get a better chrome result the parts have to be cleaned up.
With the extensive use of chrome came the polished engines. Actually the factory did produced some bikes with polished engines and parts during the 80's as this polished brake hub's on this bike. Pictures issued in an early CJ parts catalog from the 80's.
People often ask : Is there any issues with polished engines, such as over heating ?
The answer is : polished engines do not dissipate heat better than a rough casting engines.
Also to keep its shine a polished engine will require "high maintenance".
Another weak point of polished engines : some of the polished engine's case can crack due to excessive material removal during the polishing.
Beside those, a polished engine on a correctly chromed bike is a piece of art.

WHAT ARE THE DIFFERENT ENGINES USED WITH THE CJ MOTORCYCLES ?
Chang Jiang motorcycles come mainly with 3 types of engines although during all these years more than 3 models of engines were built.
Before talking about these engines in details, let's have a review of the engines :
- CJ 750 engine, the first one(1957-9 till 1966). see pictures here :
-CJ 750 type 2 engine (September 1966 till now) :
-CJ 750 D engine (mid 80's till today) :
-CJ 750 E engine (early 80's till Unknown) :
-CJ 750 F engine (Mid 80's till today) :
-CJ 650 E engine (custom made by LRM using CJ 650F engine as a base) :
-CJ 650 F engine (unknown. till the 90's) :
-CJ 900 engine (1976 ?- till 1980 ?) :
 
These are the main engines. There are other engines that are variations of these engines.
Now we are going to ask the often asked questions : "what engine is the best ?"
To answer this question, we will just tell you what are the best and weak points of these engines :
 
CJ750 side valves, 6 volt :
 The original engine, simple design, easy maintenance. A bullet proof 6 volt electrical system that, makes it very reliable if built with original parts.
No electric starter. Lights are find not bright enough by some people.
 
CJ 750 D, side valves, 12 volt :
The same general design as the 6 volt, but feature electric starter and automatic advance instead of the manual advance of the 6 volt.
It's electrical problem are its weak point. In an original configuration, its electrical will be a source of trouble.
Will heat more than the 6 volt on long rides. People like it because of its electrical starter and the possibility of using a stereo with it. (In China many young people have big stereo system on their Changs. Thanks to the 12 volt system)
 
CJ 750 F, OHV, 12 volt :
 
Called by some the best engine. Offer better speed increase, than the side valves, say to heat less (although that a well tuned and adjusted and well driven side valves engine will not over heat).
Need a bit more maintenance. If its valves are not well adjusted and checked they can bend.
Suffers same electrical problems than the side valves 12 volt.
At the origin, this engine was not designed for the M1 series plunger frames. So it is needed to remove cooling fins on the bottom right hand cylinder's head, when the bike is fitted with a sidecar.
Also not a lot of space for the brake pedals and the tyranny foot shifter.
Need to separate bike and sidecar to perform valves' adjustment as not enough space to remove the valves' cover.
Its faster speed increase and little more horse power make it attractive to some.
 
NOTE : ALL CJ ENGINE DO PRETTY WELL WHEN PULLING A SIDECAR. SOME CLAIM THAT THE 22 HORSE POWER AND 24 HORSE POWER OF THE SIDE VALVES IS NOT ENOUGH AND NOT BETTER THAN THE 32 HORSE POWER OF THE OHV ENGINE. THEY FORGOT AN IMPORTANT POINT : TORQUE IS WHAT MATTERS WHEN PULLING A CHARGE, AND ALL THE CJ IN THEIR ORIGINAL CONFIGURATION HAVE ENOUGH TORQUE FOR IT.
 
We have talked mainly of 3 engines as they are the ones often the most with the CJ motorcycle.
WE HAVE HEARD ABOUT 6 VOLT OHV ENGINES, WERE THEY FACTORY PROTOTYPE ENGINES OR PRODUCTION ENGINES ?
They were full production engines. For anyone with good knowledge of the CJ 750 history, they know that these were made in the early 80's.
Mainly 2 types were built :
One with manual advance :
And one with automatic advance :
Bikes were built with these engines and sold. The engine was even in a spare parts catalogue along with pictures of the bikes that were fitted with these engines.
These 3 bikes that went under production and are featured in that early 80's catalogue are the living proof that CJ 750 E OHV 6 volt engines were never prototypes or "samples" engines but real production engines.
They were not produced for a long time due to the following reason :
The Chinese encountered a problem when they built their first OHV engines. Due to the higher RPM the OHV engine's camshaft will worn very quick due to a lack of lubrication. This problem occurred with both, 6 volt and 12 volt OHV engines at an early stage of production. When they solved the problem by adding a brass pipes with holes on the top of the camshaft that will drop oil on it, to avoid it to worn out,
they stop the production of 6 volt OHV engines and continue the 12 volt only.

WHY DOES LRM USE NON CHINESE BEARINGS IN THEIR ENGINE REBUILT ?
The use of non Chinese bearings is not a new thing. This is not known by some but during the 70's the factory started using Japanese Nachi bearings in their engine. 3 years ago LRM bought some N.O.S engines from the PLA, all from the 70's. Before using them we took them apart to check if after more than 30 years in the stock everything was fine. That is when we discovered that they were using Nachi bearings :
"Clay Jones recently bought an N.O.S 1974 PLA-issue engine from Gerald. The big surprise was finding Japanese Nachi bearings inside straight from the factory. There's no way counterfeit Japanese bearings were being produced in China back in 1974. This is a very interesting matter since it further illustrates the high quality that went into CJ engines from this period.

On the left is the certificate that accompanied Clay's engine. The bearings appear on the right. The builder was the State Owned Hong Xiang Jiang Machine Manufacturing Factory."
 
LRM is not using other bearings than the Chinese ones just for marketing purposes. We use C3 bearing for the engine. These are the correct bearings that should be use for an engine. With 6 years of riding experience we have noticed that the engine bearings last much longer when we use other bearings than the Chinese ones. And also we used sealed bearings for the wheels. They last longer than the Chinese standard bearings and the Chinese sealed bearings.
If someone wants to get a quality built CJ engine, we will advise to use other bearings than the Chinese one. When we rebuild an engine we change every moving parts, cylinders, pistons, rings etc... So why not use better parts when you are rebuilding that engine ?
An example of bearings quality :
I have an early CJ sidecar frame without suspension (http://www.changjiangunlimited.com/2006/06-0510-GG-1002.jpg), what means that it is just an axle supporting the wheel. You side wheel suspension are the wheel's spokes and the tire. With Chinese bearings after hitting the ground hard, you'll have to change them at least every 2 months. With FAG bearings, I did change them after 2 years and after a ride in the Gobi desert. No roads, pure off-road. This is how better are the FAG bearings compare to the Chinese one.
 
ARE ANY MODIFICATIONS FOR  THE USE OF TAPERED STEERING BEARINGS FOR THE STEERING HEAD (TRIPLE TREE) NEEDED ?
No. You do not need any modifications to install tapered steering bearings on CJ instead of the ball bearings. If you get the right size, and it is available, you just have to put them in and that's it.
Check the different pictures :
http://www.changjiangunlimited.com/04-1221-CJ-1002.jpg
 
ARE THE ROLLER TAPERED STEERING BEARINGS BETTER THAN THE BALL BEARINGS ?
Yes. They are easier to install. Do not need to be retighten as often as the ball bearings. Last longer. Reduce the wobbling of the bike. 95% of our customers require these bearings when we restored bikes.
If you have tried once the tapered bearings, you'll never want the ball bearings anymore.
 
WE OFTEN SEE TALKS ABOUT CARBURETORS, 30mm, 24mm, 26mm and 28mm. WHAT ARE THE ISSUES REGARDING THE CARBS ?
2 or 3 years ago, "new carbs" came on the market. They are the 30mm. They are at the origin, Mikuni knock off. They are designed for 2 wheels motorcycle. That is why they only come with one side.
Many people think that if you use bigger carbs the bike will perform better. It is not really true.
The CJ motorcycle design is at the origin a BMW design. When creating the BMW R71 in 1938, German engineer fitted the bike with 24mm carburetors. This was done after calculation. If the bike needed bigger carbs they would have fitted it with bigger ones.
As a matter of fact we have made the following experience :
We took a side valves bike, we fitted it with 28 mm carburetors and went climbing, the result was we had to shif to 3rd gear. We did the same experience, same hill, same bike, but with 24 mm carbs and we could climb still in 4th gear.

Why do the 28 mm carbs do not work better with the side valves ?
Because of a too big throttle inlet diameter. Wrong under pressure in carb and cylinder gets too less fuel. 
You want to run bigger carbs ? then get bigger valves !
Bigger does not mean better. The CJ side valves run best with 24mm carbs and the OHV's with 26mm.
The sad thing is that 24 and 26 mm are no more produced. Only the 28mm are available.
LRM has some stock of 24mm but they are mostly kept for restoration of original vintage bikes from the 60's.
One important fact regarding the new 30mm carbs. Some claim that they run better, but we have had the following reports recently :
http://autos.groups.yahoo.com/group/thechangjiangexperience/message/13853 (the bike mentioned in that post uses 30mm carbs)
http://autos.groups.yahoo.com/group/thechangjiangexperience/message/13600 (the BIG CARBS that are referred in that post are the new 30mm)
Beside some problems, there are no spare parts available for these carbs if ever you got a bad float or anything else.
That is why at LRM we will let you know the bad and good for any products we are selling. Knowing these you are able to make the right decision.
The standard CJ carburetors are strong, they can handle tuff environment and still work. You can even put a piece of cork as a float and make it back home. Spares ae available and at good price. What are their weak points ? They pollute a lot !
The way their bowls are located you can have vapor lock problems. But with a well adjsuted bike you can avoid these and also you can use better carbs gaskets between the cylinders, such as these insulated carb gaskets offered by John Heim of CJU US : http://www.changjiangunlimited.com/2006/06-0305-JH-1001.jpg
(John can be contacted at JohnH9097@aol.com or : laurent1@adelphia.net )
Their plastic floats sometimes go bad. The solution ? Use brass floats available at LRM :
WHAT ABOUT THE FRONT DISC BRAKES AVAILABLE FOR THE CHANG JIANG MOTORCYCLES ?
Chang Jiang motorcycles nowadays can come with front disc brakes. For many people the lake of braking performance is a big concern.
So with the new front disc brakes many are happy. When anyone ask LRM about the front disc brake, we tell them that we have it for sale but that it is not as safe as the standard brake. How come do they ask ?
Well, the standard CJ brakes have been on the bike since the 50's. We know how it works and we know its limits. That is what make them safe. Why ? Because when you know what is your bike's braking performance, you ride according to it so you stay safe. But with the disc brake, you think that you'll stop like a modern bike and when what happen to this gentleman (http://www.changjiangunlimited.com/07-0703-ann.htm) happens to you, you are in trouble ! So before buying a set of front disc brake, just think about the good and bad points !

 

ADVICE

1) Do not ever forget that you are riding a bike designed in 1938. This is not a modern bike!

2) You should know how to maintain and/or tinker with your bike all the time. If you love old motorcycles, this is the fun part of owning an old motorcycle and CJ's are no exception.

3) Check your engine's oil regularly. Every time you ride is best. At least every week.

 4 (Do not) use straight pipes.

5) There is absolutely no confirmation that the new zero emission exhaust system available on Chang jiang 750 meet any of the EPA requirements. The report about the test in China is available at Long River Motorworks.

6) The electronic control on carburetors has been cancelled, but the catalytic converter has been upgraded.

7) Blue Loctite! Know it! Love It! Use It!

8) Hylomar is an excellent  thread sealant for things like drain plugs and petcocks.

9) Use a flow meter for carburetor balance

10) Never eat anything bigger than your head.

11) Chrome won't get you home!

 12) Buy all your parts and bikes from Long River Motorworks

 
Questions and Answers

Question - Hello, I have come across a Chang Jiang 750B-2 motorcycle with a sidecar.  It does not look like it has run for several years.  I would like to know any and all the information on this model that you can tell me.  I know it is/was a police bike, but I would like to know the year and other specifics.  And how much/ little should I pay for this thing if it is worth trying to buy?  I have attached some pictures that may help.  Thanks for your help.
 

Answer - The Chang Jiang 750 B-2 bike was made in the late eighties, and the model that you have is probably from the 90's. Honestly it is not worth it to buy one of these bikes. If you are in China and you really want one of these you should not spend more than USD 100. Also you have to know that if you are in Beijing, this bike has to be destroy soon. Only M1 and M1M, M1S bikes worth money.