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Kimjon

Kimjon's Go-ped build

15 posts in this topic

At high school there was kid who had an"American pie" moment with a Swedish exchange student...poor guy saw out his days at high school with the nickname "2-stroke"... sorry funny story that always comes to mind if someone says "2-stroke".

Anyway, I've always had an affinity for 2 strokes. My parents weren't rich, so my love affair with these engines wasn't realised until I had an income of my own.

My first purchase was a MX bike. A 125cc then moved on to 250cc of craziness!

Then a 12A rotary RX7... technically a "2-stroke". Cheap speed, fun times! And although I'm more into my V8's now, I'm not afraid to admit the odd rotary catches my attention, and makes me smile.

Next was a Kt100 gokart. You'd wonder how a 100cc engine could produce so much power...actually I still do wonder how - absolutely incredible!

Then came gopeds. I have 5 goped sports, all in various extremes from near stock to insanity! This is my dream build...this bad boy will be nuttier than squirrel shit! I just finished the motor today, its a hybrid...I won't bore you with details, but lets just say it will be fast:)

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The expansion chamber is a work of art!

Anyway, the above is the result of the dangers of the internet and a paypal account;)... let this be a warning!

Oh and while my wife and three kids are away on school holidays...hell yes this gives me the right to build a gas engine on the kitchen table!

 

Started off as an already high spec little engine at 22.5cc.

The cylinder head had 4 transfer ports...these have been port mapped and ever so slightly ported to change the port timing a tiny bit. The head has been replaced with a hemispherical dome head specially calculated to the right volume to run on 95 octane gas/oil mix. The new cc rating is now 28.9cc due to larger bore of new top end. The flywheel has been lightened. The timing has been advanced. Massive dominator tuned expansion chamber. Huge walbro carburetor. Velocity stack. K&N filter. 0.7" drive spindle. Third bearing support added. Chrome fan cover and pull start.

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Yes...lost the plot...but everyone needs a hobby eh.

You'll have to use your imagination a little at this stage. 

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But this pile of "parts" will be made into a goped roller...the motor will go on it. Will be badass!

The frame I picked up didn't quite live up to the trademe description...but beggars can't be choosers. These aren't that easy to come across in NZ.

So rather than dwell on negatives, I welded up the broken bits, and stress fractures. 

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Next came a trial fit, a few extra holes were needed. And with the magic of a mig welder and a grinder...a few holes disappeared!


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I've got to figure out forks and some form of head set arrangement to hold it in place. Handle bars will then be the next headache. But I like a project and an idea (cheap idea) will come to mine:)

 

 

Frame all finished. Found more stress cracks, drilled holes in the ends of the cracks (old trick, logic being that a crack will stop at a hole) then ground out a v into the crack and welded it all back again. Finally ground the welds back flush and you'd never know any different. 
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I took it all back to bear metal, and dropped it off at local car painters for a coat of etch primer and some 2 pak paint. I looked at other options briefly...then thought paint is as good as anything else, and secondly it is just a big kids scooter after all, not a show car.

 

 

I milled up this plate up. The rear fender was snapped of the frame, I could have replaced it like for like...but I had this idea in my head for something a little different.
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I think I will look the part once final assembly takes place.

 

 

Started the motor for the first time today. It roared into life with relative ease. I soon realised it was starving for air, so tore it down again looking for reasons why. Didn't take long to see why, the velocity stack had an internal diameter of 15.4mm, but the carb internal diameter is 19mm!
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I bored out the inside, then while it was dialed true in the lathe, thought I'd contour the shape to aid flow. Pretty happy with how it turned out.

 

 

Okay, things are happening fast with this one.

Here's a before pic of what I was dealing with:
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And after:
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Chrome "bothy" forks
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DDM Racing third bearing support

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My milled aluminum rear fender:

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Tank, with billet DDM cap all installed with my own lathe turned aluminium spacers.
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That's it for now. I've ordered a few parts off ebay that I'm waiting on to complete this project with. I'm going to machine/weld up the handle bars this week while waiting on ebay parts to arrive. I'm pretty happy with the silver...I've been known to say unkind words about silver in the past...basically it does suck as a paint colour, but for this project I think it compliments the chrome nicely without being overly tacky? I'm going to put some blue parts in the mix too break it up a little... all will be explained later.:D

 

 

Had a cool idea for a kickstand. The originals had a large two sided loop. Hard to explain, but irrelevant as I didn't have one anyway. So I welded this up:
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And lean it to the right and it automatically "springs" up under tension. The spring holds it out of the way...pretty trick!
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It's the devil in the detail:)

 

 

MKII model:
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I had to make it clear the part where the deck bolts on, as I forgot about the rubber isolator. Looks a bit more shapely now with a few more curves:D[/QUOTE]

I'm skipping a lot of the detail in this thread. Things take hours of time to make and involve countless steps in their production...but that would be tedious to read through. The motor alone has about 30 hours of my time for example.

But this is a Labour of love, I'm doing it because the inner child in me always wanted one like this...and now I'm doing something about it;)


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I made these handle bars up. The original bars were fucked! They used OD28mm x 0.8mm wall aluminium - I guess to save weight, but they are very fragile. I managed I find some 3mm wall thickness aluminum, but in OD30mm. The bottom clamp is for a mountain bike and is ID32mm and the top bar clamp is a goped performance part with an ID of 28mm...problem!!! But after some head scratching I made a shim to increase the bottom of the pole to 32mm and I turned down the top of the pole to 28mm. Result!

 

 

My parts arrived from the U.S. today. Ebay rocks!

Anyway, just waiting on one last package, some fancy billet clamps, but for now two $0.02 cable ties will do just fine.

So as they say..."that's a wrap!" The photos don't do it justice, I spent hours polishing all the aluminium to look like chrome, and every detail has had an obsessive amount of attention. 

My wife is back from her holiday, I can see her eyes glaze over as soon as I mention this project...I'm going to be banned from talking about it around her soon, I can feel it:D
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So as silly a project this is, I'm pretty happy with what I've made. Now is time to ride it, well maybe tomorrow...it's dark outside and raining right now...:D

 

 

"America - Fuck yeah!" Yes, the puppets from that movie Team America said it best. Ignoring Donald Trump, a history of keeping slaves and the KKK and all the other negatives...there is some seriously cool shit made there. Think of most really cool stuff like AR15's, Harleys, Chevrolet cars, monster trucks, motor cross etc etc... America, Fuck yeah!

And from the land of the free arrived yet another awesome little package. It contained the nicest set of cable clamps money can buy...and after a quick rebore from 28mm out to 30mm to suit my home made pole, they looked ever so awesome on my goped:

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So that's it. All done!

Kj

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...So is it fast?!

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14 minutes ago, flyingbrick said:

...So is it fast?!

Yup!

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Is it wrong I want that engine for a weedeater of doom?

 

 

/Nuts looking little scooter!

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10 hours ago, Kimjon said:

Yup!

How fast

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9 hours ago, Seedy Al said:

How fast

Does about 50kph....maybe more? but it gets there super quick!

Its direct drive, no clutch. So once started, you've gotta keep moving. It doesn't like you dumping gas into it from uber low revs, but if you bring it up to a running speed then flog it...you'll pull wheelies!

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Cool little project.

Does it do skids :P

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that sounds rad lol

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Here's another one of mine. This is a fast goped...but not as fast as the one in this build thread. In the quick and nasty YouTube clip, I'm only about half throttle as there isn't enough room to flog it. My latest one bogs at low speed, so it's pointless riding that one unless you have more room to hit the higher rpm's.

Anyway, thought it would give you an idea?

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I built a few Go-Peds back when I was 11-13, still have one. Ill see if I can dig up some old pictures of it. Got Trevor Simpson reed cases, ported, 14:1 compression, ran it on methanol for a little while but too much up keep for a toy. It was pretty quick, would rev out to 19-20k rpm, I could be hooning down the foot path on a main road passing cars doing 50-55kph...

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13 minutes ago, PedRac3r said:

I built a few Go-Peds back when I was 11-13, still have one. Ill see if I can dig up some old pictures of it. Got Trevor Simpson reed cases, ported, 14:1 compression, ran it on methanol for a little while but too much up keep for a toy. It was pretty quick, would rev out to 19-20k rpm, I could be hooning down the foot path on a main road passing cars doing 50-55kph...

Would love to see some pics please.

I have some reed valves off another two stroke, when time allows I will have a go at milling something up for this motor.

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Couldnt find any of my old photos, used to have heaps, but this was nearly 13 years ago (Im 26 now)... Been lost through the few PC's over the years I guess. I dug it out of storage though, exhaust and other bits and pieces have some surface rust on it.

TS Reed Cases, 2mm stroker crank, ESP ported cylinder head with the combustion chamber re-machined, Tillotson carb, ADA S1 pipe. Frame has a 3mm fender fully welded... as you know they break off after time. Billet wheels, rear needed a beadlock from memory, as the rubber would begin to expand and seperate from the wheel which felt pretty dodgy at high speed.

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You get a really good powerband with the reed valve over piston port. Used to be kinda peaky when it was piston port, with power coming on around 8k rpm and hauling ass to around 17k then slowly dropping off to 19k, power comes on much sooner and a little better up top.

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12 minutes ago, PedRac3r said:

You get a really good powerband with the reed valve over piston port. Used to be kinda peaky when it was piston port, with power coming on around 8k rpm and hauling ass to around 17k then slowly dropping off to 19k, power comes on much sooner and a little better up top.

I'm certainly interested. May have to geek out on the internet and try and find more information.

Like you, I was into gopeds a long time ago (nearly 20 years ago for me)...I'm rediscovering how awesome they are. These days I've got a few more tools to do cool stuff with :-)

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