Pushbike Motor failure

The engine on my pushbike started to make some strange metallic noises, began to retard, then seized up. An autopsy was required. :-(


After the less than desirable job of removing the engine from the bike, I popped the side open and found this little guy sitting in the oil at the bottom. Though I can't find any matching break point here.



The oil pickup gear, and cam-gear seem fine. The pushrods seem fine too...hmmm...



The entire block splits diagonally right through and I really don't want to crack it open if I can avoid it.



Alas everything looks fine under the itty-bitty rocker cover.



I'm going to have to split this thing open. Though I can't get a socket or wrech on this little guy. I've already damaged it with a screwdriver :(



...so I carve away the serves-no-purpose-hopefully housing around the bolt with the dremmel...



...and I can get in there no problems.



It just won't pry apart though. I'm gonna have to get the flywheel off. I've already tried once with a really nasty claw style gear puller and ever so slightly bent the flywheel at the rims already. Blargh!!!



So I made my own gear puller by removing the claws from the cheap puller, and simply drawing up against a piece of scrap metal with some bolts nested in the flywheel. Worked first try, just like a gear puller should !!!



Turned out there were 4 bolts under the flywheel anyhow. So once they were out the sucker split open and found the break point almost immediately. Right at the end of the screwdriver. Turns out the part is an oil dipper-thrower thingamabob and I have no clue how it broke. However it clearly lubricated the big end bearing and piston as both were bone dry, and the engine was seizing up after ~60seconds of running every time.



I found a replacement part online from the States for ~$4, but shipping was ~$18. The local mower place isn't open till early January. So I decided to make my own dipper. Here is the broken one taped together to show its original state. Behind it is an unlucky latch which probably won't be a latch for much longer. I can't vouch for the quality of the steel...but I figure it's worth a try.



So uh...that just happened...



I'd like to order one of those.



Hammer time.



Rough as guts.



Filed down.



A coat of 650C paint. Done. All hail year 7 metal shop and a handful of Kmart tools.



And like a bought one, bolted back onto the engine.



It took me a while to find the alignment marker on the plastic cam gear as I was looking at the other side (from an earlier picture). You can see here I've got it wrong...but that got sorted.

So some silicone gasket sealant on all the seams, and bolt it all back together. Hopefully it should last for at least 10 minutes!!


edit: Everything worked great for ~90 seconds after reassembling the entire job. Then the engine stopped and any ignition attempt resulted in a complete freewheel. I assumed the clamp on the big-end-bearing had come off, and that's exactly what had happened :( Blargh I hope nothing is seriously damaged...


MEDIC !!



Jimmy!! Jimmy!! Speak to me Jimmy !!!

Merry Christmas 2011 !!

50cc Pushbike Motor Kit. Part 3

I needed to make some modifications to the motor-pushbike. Previous build info is here (day 1) and here (day 2).


You can see here the clearance for your foot is pretty lean. The gearbox sticks out a ways, and the other side is similar.



The vertical clearance is somewhat lacking...



I'd like to extend the pedal about "this much". You can import pedal-extender-bars, but they're a specialist product, cost about $25-$40 a pair, and only extend about 2cm.



I had a spare set of pedals kicking around (why? because I'm awesome, that's why.) so decided I could modify them to make some sort of super-pedal.



Aluminium cuts like cake. I really need a larger vice. The drill vice isn't really meant for this.



So I broke my last blade. Blargh Bunnings trips in the middle of a build are a pain in the bum.



With any luck I can just bend the leaves around the existing pedal, bolt it, and be done with it.



No such luck, cast-aluminium. Snapped in my hands, didn't even needs tools to break this. :(



So I cut the remaining leaves off, and got started on the other pedal.



Bunnings forced me against my will to buy das-uber-vice. It's a sweeet 150mm bar with who knows how long an extension, with offset clamp. I've actually never used a clamp this beefy before. It weighs 17kgs on its own. For scale, the hacksaw next to it has a 30cm (1 foot) blade.



The clamp is offset, so you can drop large pieces of product down to the floor while locked in the vice, with a full grip unlike most clamps. It has whacky MONSTROUS fins on both jaws to prevent any flex due to the offset grip. The jaw depth is much deeper than a standard vice also. It's huge.



Shelf-brackets have served me well for steel-strip requirements in the past. I'm going to cut these down and use them as splints to extend the modified pedal off cuts.



Aluminium drills so nicely!! I wish every metal work job was like this.



So this pretty much completes the picture of what I'm trying to do. A few bolts should have this job complete in no time.



This whole job was eye-balled. Yep, that looks about right...



They don't look too bad.



Plenty of foot room now.



Left and right, looks fine. Another victory to ad-lib workmanship. Also...I scored a new vice, so it's a double win. :-)

50cc Pushbike Motor Kit. Part 2.

Below are some photos of my second afternoon installing the 50cc motor kit to my spare bicycle. Day 1 and more pics are here.
Day 3 (pedals only) can be found here:



Rear sprocket installed and back on the bike.



The chain needed to be shortened. This was really close to the correct size. I had to take out one link. :(



Multi speed bikes have no position adjustment on the rear wheel to take up chain slack as that function is performed by the rear derailer. My new power-chain will need this issue dealt with.



The kit comes with a chain tensioner. I'm not keen on these things when they're not spring loaded but I have no choice in this situation.



It's on a proper bearing, not just a bushing, so it spins really nicely.



I did need to make a small hammer-adjustment to the mount bracket though...



The trailing arms to the rear wheel on the bike aren't parallel to the chain, so this little twist in the chain tensioner bracket should compensate for that.



The hammer-adjustment seems to have worked out ok.



Cool little exhaust.



I was curious if the exhaust was just a simple expansion chamber, or if it had real baffles in there. Turns out it was the real deal.



Totally SWEET idea for the exhaust bolts from the dude who made the installation video. The slightly-longer-than-needed bolts are threaded in by finger ALL the way, so you get a complete thread-engagement. Then you crank down the nuts to pull the exhaust in tight. I've stripped numerous bolts and studs in the past when tightening down into cast-iron components. This solution was brilliant and very easy. I'll be doing this for all future bolts where over tightening or stripping is common. (cast iron...always...)



The bike is starting to look like a 1930's motorbike. Exhaust bracket added to support the baffle end against the bike frame.



Tank and fuel valve with screen-filter built into it. Later I found I should have washed out the tank first...there is black powder residue running through the clear fuel tube to the motor. I'm just gonna run it through 'cus I'm a barbarian.



Tank on the bike. Geez if I painted this thing khaki you'd just think it was a WW1 motorcycle.



Bits left over after completion. Couldn't be bothered with the 2nd handgrip, as I prefer the rubber grip to the aluminium feel anyhow. Also don't think I'll put the chain guard on. The gearbox does a good job of keeping your leg clear of the chain.

edit: Oh I forgot to take shots of the throttle installation. It's a cool aluminium twist-grip throttle like you'd expect on a motorcycle.



Everyone knows that American Mustard makes engines run better. Oil in the motor makes them last longer too. ;-)


Some shots of the beast.







You can see the aluminium twist throttle on the right handle grip. (left in the photo) I didn't put the matching grip on the other side as I prefer the original rubber grips.





I kid you not, I pulled the pull-cord ONCE to start it the first time. Didn't make any effort to bleed the lines or any other kind of stuffing around. This thing starts more easily than my mower which has some sales-pitch "ezy-start" gimmick going on with it. I've had a bit of a hoon around this evening up and down our side street. It's completely awesome and made me smile like a little kid. Heaps of power. Good speed.

I'll need to buy some pedal extensions to get them about an inch further from the crank arms. I can pedal, but it's awkward and a little tedious. I may just hit Bunnings and make something up.

I'm already considering putting a larger pinion gear on to give a higher top speed. It has plenty of power, and the centrifugal clutch should give some leeway here.

Other thoughts are that I would like this kit on a full on Mountain Bike, not my hybrid. My body weight is fully on my butt on the seat, instead of offset by pedaling, and I want a more comfortable ride. Thick mountain bike tyres and some suspension would be perfect. I may drop into KMart at some point and just grab whatever $80 bike they've got going on the day...we'll see.

But I digress. This kit is awesome. Get one. Thumbs up. Very happy. :-)