Cleaning the chain

Simple tutorial this one but essential none the less.

Minimoto chains aren't o ring type like most motorcycle chains, they're just a very basic type working on metal on metal contact between the links. This means their life span is alot shorter but given the minimal amount of hours the bikes are used this isn't really an issue.

However due to the tiny size of the pinion sprocket and the rather huge RPM's they see, to get the most life and reliability you can from them its essential to keep up good maintenance.

So im a believer in cleaning it after every race meet along with a few other things ill post on later and of lubing the chain after every use. It seems to be the only way to get a decent life span from the standard chains. So here goes.

The tools you'll need. A 4, 5 and 6mm allen key for removing the appropriate parts, a chain breaker for the minimoto size chains and a brush along with either some petrol or kerosene.

1) Remove the footpeg bracket to get access to the chain. Unfortunately you cant take the chain off without breaking it due to the swingarm caging it in and these types of chain are continuous, not held together with a master link. thus the need for a chain breaker.

2) Next, slowly rotate the rear wheel and observe the chain links as they roll off the pinion sprocket. They should all roll of straight and unkinked. If they do roll off kinked its time for a new chain. Heres a picture of a worn out siezed chain that must be replaced.

Fortunately this one seems okay :)

3) On this bike the water pump mounts to the clutch bell and the belt is driven via the pinion, so Those must first be removed. First pop off the belt then remove the two bolts holding the pump on.

4) The 4x bolts holding the clutch cover on can then be removed and the cover removed in turn. This then allows you to take off the chain.

5) Pop the chain off the rear sprocket. Now is a good time to inspect the condition of a few parts. The chain slider - This one is in fine condition

Check both front and rear sprockets. They shouldn't be worn too thin and pointed at the tips and shouldn't have a hook pattern too them. These are both fine.

6) Now to remove the chain, a special tool is needed called a chain breaker. you can get them from most pocket bike part suppliers. What this tool does is to push a pin from the chain straight out so the loop can be broken. Here's the buisiness end of the tool. The flat tipped screw clamps the chain to keep it in place and the pin shaped one pushes the chain pin out.

So Grab the chain and place it in the chain breaker. The pin shaped screw should be aligned with one of the chain pins and the clamping screw firmly holding the chain in place as shown.

Then screw in the pin shaped screw and out should come the chain pin! After backing off the screws and removing the chain it should then simply pull apart.

7) Grab a container (a fuel safe one) and fill it up with a bit of either kerosene or petrol. I use petrol because there's plenty of it about and its not a requirement to use kerosene on these chains as they have no O-rings to be ruined. 

Put the chain in and stir it around with your brush a little. all the grime and dirt should loosen up eventually. Generally i leave the chain in for an hour or so until the petrol is filthy.

Ready!

8) Take the chain out and sling it around something and let the excess petrol/kero drip dry off it. Excuse my bodgey jig. 

9) While your waiting for that to dry grab the brush and petrol and clean off the sprockets, front and rear. Just dab some petrol on the perimeter of each then wipe it clean with a rag after a minute or two. 

Nice and clean!

10) Now take the freshly cleaned chain and loop it around the swingarm (dont make the mistake of joining it without doing this! its mega annoying) and put it back in the chain breaker. this time you'll put the pin in the flat ended screw and use the pin ended screw to clamp the chain. Then just simply wind the screw in to push the pin back in to the chain and join it.

 

11) Nearly there now. Simply install the chain back on the rear sprocket, put it around the pinion and bolt the clutch cover back in place and the water pump. MAKE SURE TO INSTALL THE O RING BELT BEFORE THE CHAIN!

12) Last step is to lube that sucker up :) Grab a can of chain lubricant. I just used any old brand i could find. Given the amount of times you lubricate the chain (once every use) the quality of it i doubt matters. 

Then holding the tube against the BOTTOM of the chain spin the rear wheel while applying a generous amount for about two full revolutions of the chain. You must do this once after every use/ride to stop the chain binding up.

Now your ready to go! once you've done it once or twice the entire process should only take about 10 minutes. Well worth it for a long life chain :)

MEGA MOD! making new chain adjusters for the cag

So as promised here it is. Probably one of the trickier projects due to having to mill steel (always tricky) but the reward is well worth it.

As anyone thats owned a cag will know, trying to remove the rear wheel to change the sprockets or tyres over is the most nightmarish procedure known to mankind. you have to try juggle about 6 pieces at once to stop the entire axle assembly falling out backwards and even then the setup is still pretty dodgy.

Determined to just rid myself of the entire setup completely... dodgy tube spacers, crushed box section adjusters and all.. i angle grindered the entire rear end in more or less a fit of rage :P Fortunately the frame is pretty thick around the swingarm.

As always the trusty cad program provides the design to work with. Heres the initial render of it. The only design change was to eliminate the rounded corners on the ends because i couldn't easily replicate them on the manual milling machine.

With that done i grabbed the nearest size of steel i could find, which turned out to be some 32mm diamter steel rod, chucked it in the lathe and faced it off then end drilled it for a 6mm clearance hole. Its reason will become clear later on.

The rod was then parted off with a hacksaw at 62mm length and refaced and the edges chamfered.  Now i can move over to the mill. 

The rods are 32mm diameter and they needed to be 16mm thick. Thus i had to machine off 8mm of thickness from each side - quite a bit! Accuracy wasnt paramount so i just touched the tool (80mm carbide face mill) to the top and used to the DRO to set the depth. 

Taking the first cut. Depth of cut was 1.5mm to begin with but using the handy gwizard calculator i ended up getting it down to 2mm with a quite reasonable feed rate. well recommended!

Nearly there.. last cut on this side. The coolant really helps with these heavy operations.

The part is then flipped over and rested on a set of parallels to keep it.... parallel :P while the other side was machined. 

And the part at this stage with a piece of the original rod. 

After making two identical pieces shown above it was then time to make the first slot for the axle to go through. There needs to be two - one 19mm and one 10mm (the axle diameter). so the 10mm was done first.

One of the best tips when it comes to milling is that drilling removes the most material for per unit of time of nearly every tool. So for an operation like slotting drilling a series of holes reduces tool wear infinitely and allows the end mill to basically finish the slot off. 

Here the stock is being drilled with a center drill before final drilling to 10mm, then the completed holes with a 10mm carbide end mill in the collet chuck ready for finishing. The digital read out makes this a doddle.

First pass with the end mill. Not tempting fate with steel the cut depth was only 2mm. With coolant it chewed through like it was nothing. 

And all done. The finish is very ordinary because i just did the slot in one pass. The proper way is to drill the holes smaller to say 8mm then make a 1mm cut either side of the slot to finish it off. Given how long it took to mill the single slots and the fact accuracy wasnt critical, i wasnt too concerned.

Next was the big slot the adjuster itself sits in. the cad called for 20mm but the closest end mill was 19mm so that was used instead.

I didnt grab a picture of it but i used an 18mm roughing bit to do the initial slot then finished it off with the 19mm using the aforementioned process. Heres the first pass at 2mm depth.

And at final depth, but using a standard carbide tool to do some gentle cutting passes for a good surface finish.

Done :) the finish on the 19mm slot is great as you can see, the 10mm not so much so, so that shows why you need to cut the slot undersize initially. Mind the rough edges at this stage, it still needs cleaning up on the mill.

After completing the 2nd one it was back into the mill to clean up all those nasty edges and start on the "nubs". These parts will fit into the ends of the box section to provide some strength in addition with the welds and also to help locate them while they are welded.

Nothing too special with the process. just cut down with the 10mm end mill. Heres the finished part.

Nearly there! The chain adjusters themselves were next to be made. nothing too hard. drilled out some 20mm rod to 10mm, then turned the outside diameter to 19mm and parted it off. The edges were then rounded off with a knife tool as seen here.

Drilling the edges and tapping them for M6 threads means the machining is done! The finish is hardly perfect but for a compartively small mill its more than acceptable to me.

Back at headquarters the pieces were lined up and welded with the TIG. And here they are all welded in. I reckon they look pretty damn good :)

All that remains now is to get a new decent axle and make some axle protectors for the ends. Then the spacers will also need to be redone and the chassis painted/powder coated.

So thats it! Hopefully your all still awake by the end of this :p

Now i need to go pick the swarf out of my hair.. ughh..