2013 - AusEx (AmEx Replica)

[OzFab]

Dilemma!

I apologise in advance for the "novel" you're about to read...

Just in case some of you don't know, when metal is chrome plated, it tends to "build up" the size of the metal, much the same as paint does. As a result, threads become slightly oversized. Easy enough to fix, you just run a die down over the thread to bring the size back down; until you come to a left hand thread as there is on the ends of my tierods

As I live very close to industrial zones, I headed out to find an engineering or fabrication shop that could help me out; with so many locally, I was sure to find one... or maybe not . Even one of the largest engineering companies in Sydney couldn't help me...

Next thought was to try the engineering supplies stores; the first one wanted $103 & "it'll be here tomorrow", The other one wanted $83 (that's a bit better) &, again, "it'll be here tomorrow".

Now, if I was going to use it every day, I could warrant the expense but, seeing as the tierods only cost me about half that much, not gonna happen...

In desperation, after almost 2 hours, I headed home & googled it, just to see what would show up. DUMBA$$!! One of the first entries was from a (sort of) local chinese tool shop: I say "(sort of) local" as it's a bit further than I had travelled earlier but still only 15 minutes away & "chinese tool shop" because it stocks chinese tool & it's also run by chinese...

I called them to make sure they had one in stock & headed over there. I ended up getting an M8 left hand die, 1" die spanner & an M8 left hand tap, all for $36. It then took me 20 minutes to clean up all the threads & put it all together...

The moral of the story: Always consider absolutely every possibility & Murphy's law sux but, it does exist...

 

[landuse]

The good ole chinese. There stock is most times sub standard quality, but you can be sure that they always have stock!!

 

[machinist@large]

Chrome.....chrome....chrome...chrome...

I apologise in advance for the "novel" you're about to read...

Just in case some of you don't know, when metal is chrome plated, it tends to "build up" the size of the metal, much the same as paint does. As a result, threads become slightly oversized. Easy enough to fix, you just run a die down over the thread to bring the size back down; until you come to a left hand thread as there is on the ends of my tierods

Another thing to keep in mind about chrome plated parts is that the plating process introduces hydrogen embrittlement into the surface structure, which can cause cracks to form, potentially leading to failure. If memory serves, I believe that can be remedied (at least partially) by heat treating the parts in question. That's why it's generally frowned upon to plate suspension components, especially springs. In the case of your kart, the loads are generally going to be small enough that you shouldn't have any problems. And yes, chrome is an additive process; a proper, quality job will add approx. .003"~.005" (.08~.13 mm) to the size of your part. So if you need the part to fit after plating, you need to keep that in mind. A good plating shop should be able to tell you roughly how much they are going to add to you parts in advance if that's going to be an issue.

 

[OzFab]

On the Home Stretch...

The only major job I have left to do (apart from paint & upholstery) is the brakes. I was going to use the setup I bought for the shifter but, today, I had to go to the local chinese motorcross shop for a brake cable & happened to walk past their scrap bin. Inside I noticed some brake components. I asked the fella "What's the deal?" "They have non functioning or damaged components & it's just as easy to replace the whole kit. If you want 'em, help yourself."

AWESOME! I rummaged around for a bit & dug out a few full sets plus a few bits & pieces. So far, the most expensive part of the brake setup is the cable I went there to buy Now to mount it all on the kart...

I also got my disc fitted & mounted. Basically, it's a piece of 6mm steel plate cut to size & shape with the help of my mate Pete...

With a bit of luck & careful planning, I should be driving this thing by this time next week

 

[machinist@large]

Mega score!!!!!



And you guys grumble about how good we have it here in the States!!! Adding to your other post on brackets for your caliper(s); 3mm plate is .118" i.e. just under 1/8 inch thick. With the rotor being fixed (not sliding on the shaft), it locates the caliper so it can't twist on the bracket. As long as your bracket isn't excessively long, say 150mm (~6") you shouldn't have a problem. If you do, just add another layer. Drill a couple holes in the second piece and plug weld it to the first and you'll have a bracket that if you manage to bend/ break it, you'll have a lot bigger problems on your hands.

Pat

 

[OzFab]

And you guys grumble about how good we have it here in the States!!!

Hey, this kind of thing doesn't happen every day so, when it does happen, it's braggin' time!

I have to admit, for the most part, I've been pretty lucky when it comes to parts for this kart but, that just makes up for the ridiculous money I spent having the frame made...

Adding to your other post on brackets for your caliper(s); 3mm plate is .118" i.e. just under 1/8 inch thick. With the rotor being fixed (not sliding on the shaft), it locates the caliper so it can't twist on the bracket. As long as your bracket isn't excessively long, say 150mm (~6") you shouldn't have a problem. If you do, just add another layer. Drill a couple holes in the second piece and plug weld it to the first and you'll have a bracket that if you manage to bend/ break it, you'll have a lot bigger problems on your hands.

Pat

As I said in the other thread, the caliper is only about 2" from the bearing plate so, I think I should be ok with the 3mm.

Thanks for the input Pat

 

[OzFab]

Ok, where was I..? It's been a big week...

Ah, yes, brakes!

First thing I had to do was make a bracket to hold the caliper; 3mm plate, measure & mark, 2 bends & a bit of cutting & I have the basic shape. Now, make it fit around the axle! A bit more cutting & it's mounted

Now, make the caliper fit! I slid the disc over away form the bracket, positioned the caliper on the disc & slid the disc back into position. Umm, the caliper is hitting the bracket: Mark where it's hitting, remove the bracket, drill, cut, file, refit, we're in business

Now for the tricky bit; hold the whole lot together so I can move it to get enough room to mark the two brackets to create reference points. Locking pliers! Clamp the two brackets (oh, I forgot to mention, there's a bracket on the caliper that needs to be connected to the mounting bracket) to the disc, unbolt the mounting bracket & mark both brackets.

Then, disassemble the whole lot, position the two brackets together, clamp, drill 2 holes & hold the two together with self tapping screws (temporarily). Put the lot back together, NOW we're in business!

With a few finishing touches, that'll be done.

Now onto the master. Easy enough, I'll just bolt a front pitbike master to the rear crossbar behind the seat...

Umm, no I won't; the tube is 1" (25mm) but, the maximum clamp on the master is only 22mm

I contemplated cutting out a small section of the tube & replacing it with smaller tube, then I thought "that would look wrong &, if I'm gonna start cutting up tubes, it's probably easier & neater to replace the whole thing... so, I did

I carefully cut out the old tube, making sure to keep the structure intact but, leave behind the mounts so I had something to mount the new tube to.

After getting the length right & birdmouthing the ends, I struggled with the new tube to get it into position (it had to go between the seat bars & the engine mount bars With a bit of persuasion, I got it in without damaging anything.

Final step was to mount a tube to hold the end of the cable (which I had made earlier, complete with thread for the elbow to screw into), a bigger headache than I thought. It had to be positioned where it wouldn't hit anything if I ever needed to get it out (the cable that is) & angled to line up with the correct position on the handle (which I pre drilled)

 

[OzFab]

Last week, I had reason to visit my mate Pete. For those who don't know, Pete works for Qantas.

While I was there I showed him my newly repaired fuel tank (or... the two pieces of it anyway) & asked if he had any suggestions about rejoining the two, making sure to mention aviation fuel tank sealant. "Leave it with me" says he.

Tuesday, my phone rings. "Tank's done but, there's a small problem. While I was TIG welding it, the bottom of the tank came away from the mounting frame" (Honda tanks are actually 3 pieces!) "As long as the tank is sealed, no prob. I can always glue the tank to the frame". Got it home, did a leak test, perfect!

A bit of oil, a bit of fuel & (fingers crossed) the engine will be running

 

[landuse]

Nice progress Tony. You did a great job with the brakes.

 

[OzFab]

I forgot I hadn't posted re: fuel tank... Below are some before pics.

Basically, it had a big dent in it which was gonne be a pita to pull out so, I decided to split the tank & push it (& a few other smaller ones) out.

After that, just a thin layer of body filler & it looks almost new

As for the brakes: I got everything fitted & lined up, connected the hose & started pumping the master, nothing I hooked up another master & it worked fine but, it doesn't fit so, tomorrow, I'll pull the master apart & see what's wrong, I can't see it being too bad; worst case I can swith the internals
(I hope )...

 

[Doc Sprocket]

Hmmm... What was that about defective parts in the scrap bin? Meh- you'll get it sorted out. You're doing a bang-up job on that thing!

 

[OzFab]

Hmmm... What was that about defective parts in the scrap bin? Meh- you'll get it sorted out.

...& I did

I pulled the two masters apart with the intention of switching the pistons, only to find they were different sizes So, I cleaned them up, put them back together & attempted to bench bleed the intended one. I had a good feeling about it coz
1. When I was mounting it, I had a bolt sealing the outlet & the piston went hard, indicating it was pressurised &
2. When I pulled the piston out, it made a loud & distinctive "pop" sound.

So, I put the bolt back in the outlet, filled the reservoir & started pumping. Bubbles were appearing from both holes then a fountain almost got me in the face; that'll do it! I reconnected the line, backed off the caliper pistons, gave it a pump or three &

WE HAVE BRAKES!!!​

The cable is run, anchors are in place, all I need is an anchor bolt for the end & I'll be done. My attempt at making one went horribly wrong; I broke the drill bit three times before I gave up; I was trying to drill a grade 8 bolt...

You're doing a bang-up job on that thing!

Thanks but, did you expect anything different?

 

[OzFab]

Well, have I had fun today It was time to start the engine for the first time. As the fuel tank isn't ready yet, I used the tank from the shifter to fuel it, put some oil in it & heaved on the rope; nothing. No, I mean nothing happened, the starter didn't engage. So, I pulled it apart, cleaned it up & put a few drops of oil on everything. You see, I made the mistake of using grease which only made it sticky. Put it all back together & it works fine, engages as soon as I touch it.

So, I pulled the rope again with the spark plug out, there's spark; pulled it again with my thumb over the plug hole, there's compression... & lots of it! A dribble of oil to seal & lubricate the rings & bore, followed by a dribble of fuel, then the spark plug & I'm ready to go. So, I pulled the rope, nothing. Pulled it again... & again, & again, & again,& again... ok, somethings wrong.

Off came the rocker cover & I watched the valves as I pulled the rope, that all seems ok so, I pulled the plug, dropped a long scrwedriver in & watched to see if the piston was in time with the valves; TDC & the valves are rocking so, that's ok. By process of elimination, it has to be spark/ignition. I even pulled the side cover off & rotated the cam 180* thinking that may help; Nup!

I was at my wits end; I was this close (holds fingers millimeters apart) to getting on & asking you guys for advice when I decided to take the flywheel housing off & double check the flywheel key. With the screwdriver in the plughole & watching the rockers, I turned the crank until I was at TDC on the compression stroke which means the magnet on the flywheel should be right at the coil right?

WRONG! It was about 90* out (what?). So, I took the flywheel off to find the key was gone; no, not broken or sheared, just not there at all Oh, great, where is the key? Never mind, I have one in the other engine Put it in, put everything back together & tried it again.

IT STARTED ​

... & then, after running for about 8 seconds, it stopped. After it stopped, there was a scraping noise (it's not supposed to do that). Wait, I know what's happened... Pulled it all apart again &, sure enough, this time, the key is sheared Now I have to go out & find a new one! (& it's getting late)

Off to the local mower shop where he looked through a selection of woodruff keys & found a B&S key which was almost identical. Back home, put it all together again (double checking the torque setting) & tried it. A bit of playing with the choke & throttle & it started, & kept running... & running & running



It's a bit dark but, it was a bit dark (you get that at 5:45PM in winter ) I'll shoot another vid tomorrow...

The exhaust still needs work; it's a bit "blatty" right now, I hope to fix that in the next day or two as well as fitting an accelerator cable then

IT'S TESTDRIVE TIME! ​

 

[landuse]

YES!!!! Good job. I cant wait to see the vid of you riding this thing

 

[freqster]

Nice Job! I look forward to seeing it fly!

 

[OzFab]

As promised, here's a daylight vid; enjoy



I managed to sort out the exhaust before this vid. I had a 1' length of 45mm chrome plated tube laying around (it used to be the steering shaft cover on a small riding mower) so I did some calculations then cut out slots in one end; the slots allowed me to fold the end in so it would fit over a 1" tube. A bit of welding & a bit of beating & I now have a resonator which gives the engine a deeper note. Sounds good, huh...

 

[OzFab]

The moment you've all been waiting for!



This was the second run (well, techincally, it was about the fifth, more on that in a minute...); once you finish watching that vid, you can have a look at this one; watch for the tail flick as I appear from behind the van...



What actually took place...
First run, yesterday: I got halfway around the cul-de-sac & ran out of fuel.

Second run, yesterday: Got stuck on wet grass. after drifting for a bit, again, ran out of fuel.

*The reason I was running out of fuel was the fuel tank is still unfinished & can't be mounted so I only had a bowl full of fuel at a time...

Third run, today: After attempting to balance a fuel tank on top of the engine, it went about 6' before the chain came off. Lucky it did coz the fuel line from the makeshift tank got caught in the throttle assembly & locked the engine at WOT.

Fourth run: Vid 2. Once we (myself & buddy/bro Kurt) rigged yet another, even smaller "redneck" fuel tank (see pic), I took it slow to check that everything was working the way it's supposed to; steering, brakes, throttle. Once I had that sorted, I punched it & the back end let go (woohooooo!)

Fifth run: Vid 1. As you can probably tell, I didn't get a chance to really open it up but, what I do know is it's got buckets of torque & the axle sprocket is waaay too close to the ground (1/4" of ground clearance). I already have two smaller sprockets on the way; hopefully, with so much torque, I can find a happy medium between slightly higher gearing & decent ground clearance

 

[landuse]

Nice! The kart IS quick!! I don't think you should have a problem using a smaller sprocket. To save me reading the whole thread again to find it, what is the ratio now?

 

[OzFab]

5.88:1 (70:12)

 

[landuse]

5.88:1 (70:12)

You could probably use a 60T sprocket without a problem