a_craw4d's shopping trolley go kart

[Tele29]

Can you just put a drill on the flywheel or something?

[tortron]

10 hours ago, Tele29 said:

Can you just put a drill on the flywheel or something?

I have started a few if those pocket bike 2 strokes like that, using a drill you have to be quick to take it back off when it starts, or the nut unscrews itself. I think I ended up loctiting it on

[BlownCorona]

If you fit a thread to the crank somehow and then use a nut welded to a socket. When the engine starts, the thread unwinds the starter nut. 

Or do what Martin jetpack did. 12v 1kz-te starter motor with a 24mm socket welded to the bendix. Bolt it to a meter length of steel and feed it 24v.

Crouch right under the motor, hold the starter motor onto the starter dog and hit the button, with your arms braced. the throw out bendix ensures engament untill you let off the button, where it jumps back disengaged, after the 200hp 2stroke v4 hand grenade screams to life with the muffler at head height.

Scary every time 

[a.craw4d]

On 29/09/2023 at 21:42, Tele29 said:

Can you just put a drill on the flywheel or something?

This was my thought exactly as I’ve done it in the past.  This engine was always a pain to get going after sitting for awhile.  
However this time was the last straw and I snapped of the flywheel bolt.

Bugger.

 

 Meanwhile some other unrelated events were falling into line.

Picked up a load of free stuff.

Note the rotary hoe. I had no need but thought I’d have a look then flick it on.

 

[a.craw4d]

Turns out the previous owner had hard wired the kill wire to earth so it was never going to run.

Disconnect wire, squirt of CRC, couple of pulls and it burst into life.

5hp should make the shopping trolley boogie.

plus bonus noise making bits.

[a.craw4d]

On the topic of free stuff I also got a clutch and found a sprocket that will gear it to about 50kph.

 

So now we’re up to date it’s currently sitting at work awaiting a bit of spare time to chuck it all together.

 

(having toys at work is great fun, highly recommended)

[RUNAMUCK]

On 01/10/2023 at 16:40, a.craw4d said:

Turns out the previous owner had hard wired the kill wire to earth so it was never going to run.

Disconnect wire, squirt of CRC, couple of pulls and it burst into life.

5hp should make the shopping trolley boogie.

plus bonus noise making bits.

Brother, be forewarned!

You are teetering of the precipice of the ultimate Barry rabbithole.

But its okay, ive been down there, so you dont have to. Some years ago, i repowered my childhood go kart with a 5hp briggs. In my research, i discovered a forum, dedicated to these engines. The Wisconsin Karting federation have a class just for them. I did some reading, and learned a lot. Firstly, mine had a thread in the exhaust port. Reportedly they go better with the pipe screwed in. (The ex port diameter is too large for optimal performance) naturally the shape where the pipe ends (inside the block) is also critical. They were all about a threaded sleeve that screwed into the ex port to narrow it down. (This may, or may not be "class legal" for the stock engine class. Theres also an optimum length for the pipe too. (Seeing as its just a straight pipe, its not hard to make) my memory isnt what it once was, but it was 12" or 14".  

There are two types of 5hp blocks. The cast iron sleeve ( industrial motor) and the full alloy "cool bore" block. The alloy bore motor needs a piston which has been hard chromed. Otherwise the two soft metals gall each other. Theres also two varieties of side cover. one has a bearing, and th other the crank shaft just runs on the aluminium casting. The greatest weakness is the lubrication system. Theyre splash fed. Theres a sheet metal "dipper" bolted to the conrod cap bolts. This splashes the oil up to where its needed. Reportedly at apporox 4000rpms, this breaks off. And shortly there after the conrod snaps in two. And you get a window in the front of the block. (They say you can change the parts, and use pop rivits and RTV to make the block go another roound) 

Better parts have the dipper cast into the rod cap. Believe it or not, there is (or at least was) untold aftermarket parts available. Wiesco pistons, carrillo rods, brand name camshafts.

You can even get aftermarket billet blocks. (I think theyre called blockzilla 3?) 

Now im sure youre only interested is the basic stuff to begin with.

Firstly that pipe is a negligable cost improvement. And as tempting as it might be, dont shave the head. The air speed is highest up near the roof of the chamber. Skimming the head to try bump compression will hurt the flow.

Looking at the block with the head off, youll see an "eyebrow" between the valves and the cylinder. You can grind with down the cylinder wall, almost to where the top ring sits at TDC. Again the air speed is low down here, but its a free mod for moar power.

[a.craw4d]

On 04/10/2023 at 15:11, RUNAMUCK said:

Brother, be forewarned!

You are teetering of the precipice of the ultimate Barry rabbithole.

But its okay, ive been down there, so you dont have to. Some years ago, i repowered my childhood go kart with a 5hp briggs. In my research, i discovered a forum, dedicated to these engines. The Wisconsin Karting federation have a class just for them. I did some reading, and learned a lot. Firstly, mine had a thread in the exhaust port. Reportedly they go better with the pipe screwed in. (The ex port diameter is too large for optimal performance) naturally the shape where the pipe ends (inside the block) is also critical. They were all about a threaded sleeve that screwed into the ex port to narrow it down. (This may, or may not be "class legal" for the stock engine class. Theres also an optimum length for the pipe too. (Seeing as its just a straight pipe, its not hard to make) my memory isnt what it once was, but it was 12" or 14".  

There are two types of 5hp blocks. The cast iron sleeve ( industrial motor) and the full alloy "cool bore" block. The alloy bore motor needs a piston which has been hard chromed. Otherwise the two soft metals gall each other. Theres also two varieties of side cover. one has a bearing, and th other the crank shaft just runs on the aluminium casting. The greatest weakness is the lubrication system. Theyre splash fed. Theres a sheet metal "dipper" bolted to the conrod cap bolts. This splashes the oil up to where its needed. Reportedly at apporox 4000rpms, this breaks off. And shortly there after the conrod snaps in two. And you get a window in the front of the block. (They say you can change the parts, and use pop rivits and RTV to make the block go another roound) 

Better parts have the dipper cast into the rod cap. Believe it or not, there is (or at least was) untold aftermarket parts available. Wiesco pistons, carrillo rods, brand name camshafts.

You can even get aftermarket billet blocks. (I think theyre called blockzilla 3?) 

Now im sure youre only interested is the basic stuff to begin with.

Firstly that pipe is a negligable cost improvement. And as tempting as it might be, dont shave the head. The air speed is highest up near the roof of the chamber. Skimming the head to try bump compression will hurt the flow.

Looking at the block with the head off, youll see an "eyebrow" between the valves and the cylinder. You can grind with down the cylinder wall, almost to where the top ring sits at TDC. Again the air speed is low down here, but its a free mod for moar power.

Ok I’m out of that rabbit hole. I joined a bookface group of Americans dedicated to the B+S engines. Raptor is the 1 you speak of.  

I’ll skip all their nonsense and just keep it super simple.

Flushed the engine and chucked in some fresh oil.

Made a separate choke leaver and tightened up the governor spring a bit.

Will run the short straight pipe as it fits in the back of my work van that way.

 

Also cut off all the unneeded bits on the trolley including foot pedals. Will run hand controls purely for more cabin space.

 

Engine just sitting in place. Clears axil and handle bar, it was ment to be.

Have a new sprocket to machine and fit soon.

[a.craw4d]

On child care duties so left them unattended and got some workshop time.

Measured sprocket alignment and set up motor mounting plate.

 

 Welded and motor bolted in place. Will brace the mounting plate to back up under the handle bar.

 

 I have a video of the motor running.

 It’s stupidly loud.  

I may or may not do anything about that.

 

 Just need to drill and mount the sprocket and sort a longer throttle cable.

[a.craw4d]

 

[a.craw4d]

Oh yay I can now share videos.

 Here’s an old one with the last motor.

 

[RUNAMUCK]

Are those 4" wheels?

My old kart ran 4" tyres with a 5hp briggo.

It could wear a brand new tyre (like that ones on the front) down far enough to pop in less that one tank of gas.......

[a.craw4d]

1 hour ago, RUNAMUCK said:

 (like that ones on the front)

JUST like the ones on the front?

Exactly like those ones?

 I think you’ll find they are your old ones! They were delivered buy Karl iirc.

 The rears come from smokinjoe, (is he still around?)

 I don’t think the rear axil will last long with the 5hp to be honest but I can make a better one when that happens.

[RUNAMUCK]

The ones on the rear are what my kart ran when i was a kid/when it was first built. (When it ran a 3.5hp Kawaski) it was only 1wd. Once we smoked the first one, we ran ones like the front o  the driven wheel. Brcause they are so soft, the 5hp shreaded them with ease. 

[BlownCorona]

years ago i put a 5" sackbarrow tire on a yamaha mint for a burnout and it last 4 seconds. you can get solid sackbarrow tires which i assume would last for ages, longer than your vertebrae anyway 

[a.craw4d]

Beefed up the engine mount and fitted sprocket.

 

[a.craw4d]

This gives you an idea of the size and proportion of this thing.

It’s quite rear heavy, will be interesting to see how well it turns.

[igor]

Pop a wheelie mate.

[RUNAMUCK]

My old kart hd some shonky pitch sprocket on the axle. The clutch sprocket was 3/8 ASA pitch. The bottom sproket was something else, but the ASA chain seemed to fit. (Well enough)

[a.craw4d]

This has been sitting at work awaiting some love.  

The boy had water polo practice early this morning so I had some spare time at work.  Chucked the chain on and started it up. A little squirt of gas and it shot across the workshop. Sweet as I’ll jump in and try it up and down the side street.

 Holey shit it hooks up fast and does an easy 50 clicks.  At this point I see the errors in my actions.  

 I’m kneeling and steering with one hand. The other hand is on carb throttle duties.

 I have no brakes hooked up and it free wheels with the clutch. No engine braking what so ever.

 So I’m now doing 50 plus kph, kneeling on one knee while the other leg gets thrown out onto the road for desperate braking.   
 It works,  just.

 So I rinse and repeat a few more times because it’s great fun and why not.

 

 Anyway, I didn’t die.

 Did just go and buy some long cables though to get some brakes and proper throttle set up.

Pics as hooned.