ADVrider (
-   Some Assembly Required (
-   -   BUDGET track bike in China (

mfpthebronze 05-01-2012 09:05 AM

BUDGET track bike in China
Right, so don't expect a lot of posts. This is the 3RD time I've tried to write this. Every time I try to insert an image or something else, I've been getting booted, blocked, and disconnected.

"The wicked flee even when none pursue" - So it is with the internet (and everything else here). Try to link a photo? Must be exposing "non-harmonious" material.

SOOO, now that that's out of my system :)


Round three!!

Just as the title says, this is a budget build.

The priorities are as follows:
1. Spend as little money as is safely (or unsafely) possible
2. Make something that is fun to ride at the track
3. Use parts that are not a PITA to find in China

Lets start with the second priority and a little back-history -

I have been living in China for 4 years now and riding motorcycles (motorbikes for those on the wrong side of the pond ;) the whole time. When I first arrived I met up with some guys who were into riding like I was and we have all through a series of events moved from one part of China to another. We now find ourselves in the southern city of Shenzhen which borders Hong Kong. As with many big cities in China, motorcycles are banned within the city limits. Problem is that the "city limits" are defined by the whim and mood of those who enforce such things (as are all other laws here). So it's REALLY hard to get your riding fix when it means having to leave the city only to be able to ride in urban wasteland.
We then found that the local kart track allows bikes on the track. Cue first track day -

This is my mate's Galaxy XTR250. A ton of fun around the track if not a little sloppy (for my street bike tastes).

mfpthebronze 05-01-2012 09:21 AM

Which brings me to the first priority. Spend as little as possible.

We had been talking about something we could leave at the track to play with, so we didn't have to put the bikes into the back of a van and pay someone to bring the bike into the city to ride it at the track.

We looked around, but everyone wants waaaay too much $ for waaaay too little :ricky
Then we came across a Yamaha TZR 50 sitting outside in an alley. It had obviously been slowly rotting for an extended period of time. The cylinder head was of of it, and a rag was stuffed around the rod that was sticking out of the crank case. Wish I had some pictures of that, but we just kind of jumped on the chance when the guy walked out of his place to see why there were to foreigners hanging around looking shady. After some mild haggling we got the bike for 500RMB ($79). Split that 3 ways between us and we are on track with the first priority

Tied a rope to the back of my 250, my mate jumped on the TZR, and we towed it to the garage (the "bike shed" as we call it).

Upon a closer inspection we realized that it was in as terrible shape as we first thought. We had actually not realized it was 50cc until we were back at the shed. And the motor brings us to the 3rd Priority...

mfpthebronze 05-01-2012 09:46 AM

Parts. Man, I'll tell you something. The SIMPLEST task can be mind-numbingly difficult here. Need a gasket?? Fashion your own forge out of local debris, and smelt your own. It'll be quicker and better quality than trying to order one. Only those who have lived here will really understand how deep that rabbit hole goes.

So after a look at the engine we quickly decided that a 50cc 2 stroke wasn't going to be any fun to start with, and that it would be costly and almost impossible to find parts for (costly as in, "you want money, real money?")

So we started to have a look around for a small 2 stroke motor that is common in China. EVERY decent bike or motor here has been reverse engineered from old Japanese technology. Both with and more commonly without permission. We needed something that would fit into the frame of the TZR as well. Being as it originally accommodated a water-cooled 50cc, space was going to be tight.

After a week of searching and throwing around ideas, we found a Chinese licensed copy of the Suzuki AX100 air-cooled 2 stroke made by Jialing. Jialing is one of the largest motorcycle SOEs in China, so we knew that it would be a decent copy with plenty of parts that were easy to find. We bought it online and it was delivered to my door 3 days later, in a box covered in oil and smelling like stink. So I promptly opened it up and took a picture of it in the living-room. My wife didn't bat an eyelash :wink:

As you can see, it came with the carb, levers, and of course gearbox. We paid 700RMB ($111) which is in fact a lot. Obviously if I were back in the states, I would have found a 125cc 2stroke out of an old dirtbike that would have been better quality and far cheaper. But that brings us back the problem of sourcing parts. Blood from a stone.

This bad boy in current nic should put out a whopping 9hp or so. Engine mods are definitely on the list, but first we need to make things actually work...

More to come, but it's almost 1:00am my time, and the wife is calling :evil

whitham_wannabe 05-01-2012 10:28 AM

Superb find, that will be a slow speed riot around a kart track ...! :clap

Texas Aggie 05-01-2012 08:19 PM

I feel your pain. I have been in Nanjing for 8 years. If you have not been here, you just cannot grasp the life. The impossible can be done quickly but the easy is impossible to do at all.

Look forward to seeing how this turns out. Good luck.

mfpthebronze 05-01-2012 08:24 PM

Yes, a slooooooow speed riot :nod ....we hope.

Put the motor in the back of a taxi and took it out to the bike shed. we had been working a bit on the bike already in the mean time. Namely stripping it down and trying to clean up all the funk. There was a lot of funk.

One of the guys picked up some pads and a new rear shock at a bike market in the next city. The factory suspension on this bike was originally designed to suit 10 year-olds and small people. Add near 20 years of abuse, weather, and no love, and it was shot. Old rear shock out, new shock... not in. The metal bushing in the factory shock mount has a larger outer diameter than the new shock.

So we worked out our own special lathe to deal with the problem. Put the metal bushing on a small metal rod so it spins freely. Apply a wet rag to one side of the bushing to regulate rotational speed while the other side is pressed against a table grinder. The rotation of the grinder also turns the bushing, and gives a surprisingly even "machining" of the bushing.

After some sweat and time, rear shock was in.

Of course, the rear shock cost about $10, and it works as well as you would expect a $10 shock to work. It's too hard and too bouncy. It will probably be changed down the line if/when the bike is operational and fun to ride.

mfpthebronze 05-01-2012 08:48 PM

As you guys can probably tell, I'm just trying to catch up to where we are now on the bike. So I'll keep posting a few more in a row here until I'm caught up. And then I'll make you wait weeks for updates :D

Before ordering the engine, we were hoping to get a motor close enough in size to be able to utilize 2 if not 3 of the existing mounts on the frame. After numerous e-mails and qq messages to multiple sellers, we never really got any solid info. Half of the sellers didn't know what size the carb was, let alone the specs on the motor.

Lots of these kind of pictures were sent to the sellers help simplify the understanding

It didn't. So, we got the motor up to the bike, just held in our hands, and could easily see that there was not enough room for the motor.

Maybe if we cut all the mounts off of the frame, it would fit. So, out came the grinder, and parts started coming off.

We cleaned up the two bottom tubes and cut off the rear motor mount from the frame and tried to fit the new motor in. It fit... JUST

Looks like we'll have a few cm to play with to fit the new motor mounts onto the frame. We haven't gotten that far yet though because there are a lot of other things the bike needs.

On a side note, does anybody have any experience with the ax100 motor? We want to just run premix for this bike, but I have read online that some of the small Suzuki 2 strokes injected oil directly on to the main bearings, as well as into the fuel. If this is the case with this motor, obviously we will need to use the oil pump... anybody know??

mfpthebronze 05-01-2012 08:55 PM


Originally Posted by Texas Aggie (Post 18590567)
I feel your pain. I have been in Nanjing for 8 years. If you have not been here, you just cannot grasp the life. The impossible can be done quickly but the easy is impossible to do at all.

Look forward to seeing how this turns out. Good luck.

Nice to see another China rider on here! How is the riding in Nanjing? I've still not been yet, and am not sure if it's worth the trip or not... are bikes allowed in and around the city? If so, you may see us up there someday

mfpthebronze 05-02-2012 07:26 AM

When we brought the bike back to the shed the first time, it seemed to brake ok. Ok meaning it was able to stop from 30 kph slowly. The front rotor looks in decent condition, but the front caliper looked a bit rough :eek1

The piston wouldn't move out or in (obviously). So one of the guys took the caliper and applied his magic. Using old fashioned elbow grease, a torn up old t-shirt, and some dot 4, he got the pistons looking downright shiny. But they still wouldn't go in.

We put the caliper into the vice, and set 2 large sockets into each piston, with the sockets sticking out past the body of the caliper. Apply and remove pressure slowly until - PRESTO! Front caliper now works terrific considering its terrible condition before.

We also flushed all the old fluid out because it was looking a bit more than used

Call it a day. Bring on the beers :freaky

Texas Aggie 05-02-2012 08:16 AM


Originally Posted by mfpthebronze (Post 18590826)
Nice to see another China rider on here! How is the riding in Nanjing? I've still not been yet, and am not sure if it's worth the trip or not... are bikes allowed in and around the city? If so, you may see us up there someday

One can ride in the city if you have correct legal "A" plate but riding in Nanjing is like riding in a city of 9 million people crammed into the same square mileage as Dallas County. Probably because that is how many are here. However, get outside the city limits and there are some nice mountains to go visit. About like the Smokey Mountains with rough roads, lots of big trucks, and few people following any rules. My colleague and our wives are going to take our bikes down to YiXing this weekend to check out some interesting roads I saw a few months ago while being driven around in a cage. Could be fun from what I saw. Anyway, give me a heads up if you are heading this way. Not sure how things are in your neck of the woods as I have only spent time in Hong Kong. I can say that unlike Shanghai or Beijing, Nanjing has very few lao wei. Most days around 3,000 of us here out of 8-9 million so I do get treated very well overall and I will be happy to take my JH600 and can fire up the CJ750 side hack if you are here and we can take a ride around the countryside.

Back to your thread.....good luck. Looks like you guys are having fun and handling the China experience correctly.

richardktm 05-03-2012 09:05 AM

I'm in!!

mfpthebronze 05-03-2012 11:36 PM

Hey, there you are! RichardKTM is one of the guys working on this project. Though he probably doesn't want anyone to know; his engineering background has him cringing at some of the things we do to the bike... and yet he's so good at doing things the "budget way" :D

Back out to the bike shed and get some more work done. This time it was the front end we decided to jump into. It seemed to turn pretty smoothly when it was up on the bike stand, so I was anticipating just cleaning things up in there and putting it back together.

The upper races looked muddy, but ok. The bearings themselves were in pretty decent shape too. The grease had turned nearly solid however. I am assuming that this is the first time the front end has ever been looked into. I had to use a flathead screwdriver just to get it all out. Cleaned it all up, and came out looking fantastic

The cane is the result of a 50kph rendezvous with a motorcyclist who pulled out in-front of me. A policeman motorcyclist :asshat :rolleyes
Happened a month ago and messed up the ligaments in my right knee... another month of two of recovery and I should finally be able to hop back on a bike

Removed the lower portion of the triple tree and some of the lower bearings came with it, some did not

Looked to be the same story as with the upper bearing and races. Just need some cleaning and things will be good to go. Then a stuck my fingers up into the headstock and found the other bearings. They were broken, busted, and churned into balls of slag. Ouch! Couldn't believe the condition of these guys considering how well things moved before I took it apart

Soooo, now we need to find some replacement bearings. Again, the races were in nearly perfect condition, which I just couldn't believe! How the bearings got as bad as they were without chewing through the races is beyond me :huh

Waiting on bearings now... I guess we could always have a play with the forks..?

Also, I'll re-ask. Anybody know if the Suzuki AX100 motor injects oil directly on to the main bearings or not?

Mr. Ray 05-04-2012 05:34 AM

fun thread! Thanks for sharing.


Domiken 05-04-2012 06:32 AM

Awesome, keep it coming!

mfpthebronze 05-04-2012 07:12 AM

Great, glad you guys are enjoying it! I saw a few views, but not many comments.

It's such a cheap build, with so little invested other than time, that I'm really having a good time on it. Something breaks, doesn't work, bike burns to the ground... oh well :D

As long as people are interested, I'll definitely keep updating!

Times are GMT -7.   It's 06:17 AM.

Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2015