Restoring a JR 50 for my son

Part 1

I was given a 1982 JR50 needing a complete resto back in 2004 or so as payment for swapping an engine over in a car.

I got stuck into it straight away while my son was way too young to ride it. The project fell by the way side as other things pop up as they do.

You know how that goes.

The whole bike was pulled apart and the bike ended up in a box of good intentions going through about 3 house moves.

Well I have decided to build this up now as he's been asking if his old enough to ride his bike. He doesn't know I building the bike now.

I'm planning to have this done well before his birthday on the 22/9/10.









Here's what is planned for the bike.

-All parts sand blasted and painted in 2 pac
-Engine fully rebuilt (maybe some slight porting?)
-New chain and sprockets
-New plastics
-General tidy up

I've ordered a wisco piston kit, gasket kit, second hand crank cases and a inner clutch cover.

I also have straighten the frame as it's been abused over the years.

I can't find the triple clamps or the handles bars yet. I have no idea where they are.

I also can't find the manual I have for it.

Yes, some of you may be thinking that it would be easier for me to just buy him a bike, but I would rather spend my time and money on building him one.

If I can do it for myself and others, why not my son.

Off to surf the web for more parts and an online parts diagram.

Part 2

Here some pictures from today.



Pick up all the parts I needed from the sand blasters. Then straight to the painters to help him set up all the parts on stands ready to paint.

It takes a fair bit of mucking around, but in the end it will be worth it when it's all done.



All parts in the both ready to paint.

I received a phone call from the painters tonight saying that it's all painted and it will be ready to pick up tomorrow arvo.

I'm off to the shed now to get some more work done on stripping wheels to get blasted too.

By the way the tow bar is from my mates brumby.

Part 3

Here's some more pictures..



This is what the wheels look like now just before they go to the sand blasters.

They got dropped off today.

I'm in the process of working my final order of new parts from suzuki.

Lol at the prices though.

New fork tube inners.Just under $50 each compare to nearlly $200 for CBR.





Pick up the parts from the painters today (painted last night) and all parts sitting on the assembly bench.

I made a mistake with something. Can you see it?

Part 4

Here's some of the latest pictures that i have taken.



I mocked everything up to see what bolts/parts I still needed to complete this bike.



This is all the parts that have turned up so far. Many parts were sourced from the states 2nd.

I had an issue with the aftermarket head stem bearing kit, but they refunded my money so I bought individual bearings for the top bearing.

The barrel is getting machined for the new wisco 1.5mm over sized piston. I also did some mild porting to help the gases flow.

The barrel and head are also getting blasted. I've also asked them to skim the head.



I managed to get a very good bottom end together using parts from 3 different engines. I also modified the gear selector lever so we can select 1st and 2nd gear as the normally only have 2nd.

The bottom end also received new bearings and seals.

Waiting on wheels to be painted, new fuel tank, bush for the new fork inner and the parts from the machine shop.

The seat is getting redone as I type.

All in all it's going pretty good so far and my son now knows about the project, which is cool.

He's watching me type this now.

Part 5

So back to the resto then.



Fitted new bigger tires to the painted rims. Along with the new wheel bearings (still waiting for seals) and brake shoes it was all set to go on.



I really love the way the bike is looking (so does my son) here. It looks like an old scrambler back in the day.

Just waiting for the the tank and a few more final pieces to get all finished.

So I decided to use the old tank so I cane get it running and tune it.

That's when things started to go wrong.

Fuel was leaking from the carby. The fuel bowl had hair line cracks through it.

Meanwhile the fuel leaking decided to remove most of the paint I had used on the engine. It's the last time I'll use super cheap paint.

Anyway, so I fixed the fuel leak and I thought I would remove the engine later once all running for a repaint.

Trying to get this bike running was a challenge. It had spark, fuel and compression.

It finally started and after a few starts it was making some strange noises.

I only had running for about 15 seconds and I heard what seemed to be like a piston seized.

It was also making a squeaking noise along with a hissing noise. Very strange. It's a very simple engine, so it I started to go through all the 2 stroke files in my head.

The squeaking noise was from the big end bearing that had partially seized up. I didn't understand what happened as I used the better of the 2 cranks. I even measured the side play.



So once again the engine is in pieces. The piston has some very slight marks and along with the bore it's fine to use. That was my main concern.



Here's the squeaking crank and you can see the colour of it as it's partially seized up.



I also found another problem. This seal that was installed into the crankcase must have picked up when I installed this half over the crank and the other half.

I had plenty of rubber grease on the seal and the crankshaft.

I will order a new one and I will install it after the crank cases are together. This seal sits under the magneto.

It all makes sense after seeing this. Massive air leak causing it to run lean/hard to start. Also the con rod must had some mild surface from sitting around and all went bad upon start up.

Frustrating, but at least you guys know now things don't always just fall into place with me.People tend to think that I'm a magical being with oil in my veins. I bleed just like you when I have a spanner slip (which I haven't had in years)

I'm just a very persistent person.

Part 6





I ordered a brand new complete carby, new con rod and the bearings. Also the tank turned up along with another gasket kit. Got it all back together and fired it up today.

I couldn't sleep so i went into the workshop at 4am to finish it off. I brought back home around 7am this morning when the kids were having breakfast and started the bike I rode it through the house.

My son was so excited. He gave me the biggest hug. We went into the back yard and he rode it for the first time. He also crashed for the first time.

Now to start shopping for all the gear for him. Anyone got some hand me downs for cheap?

Well done mate, I reacon most people would have left those parts in the too hard box.The boy has got to be happy with that on his birthday !

You could always go to the army disposals for some cheap boots, not sure if they make small sizes, but thats what I started with back in the good old days.

You could always go to the army disposals for some cheap boots, not sure if they make small sizes, but thats what I started with back in the good old days.

That's a great idea. I had a quick look at the local pawn shop, but not much there. There is heaps of stuff on evil bay, but I need to work out all his sizes first.

Yes, I was tempted to just throw all the parts on ebay as it was almost a too hard basket. I pretty much got the bike for nothing and I did manage to build less than a new one. (parts only)

Only mistake I can see is, you were going to put a towbar on it,you ran out of bourbon and coke, and the barrel goes on before the exhaust !!! just joking !