My name is John, born in 1976 and living in Netherlands. Small country in Europe where "your minibikes" are very rare. Ok, we do spot a small Honda once in a while. And those Chinese pocketbikes you get when you do grocery shopping;-)
I have a Chinese pocketbike, too. And when it broke down and looking for parts I ended up here. Seeing all those nice, 4 stroke engine powered, bikes and builds. It got me thinking; I want that, too. The Chinese pocketbike is in running condition again, but it's litterally a pain in the @ss. Also another reason to make me (and my daugthers) a real minibike.
But rare as they are, I will build my own from scratch. I'm not making an exact copy of 1 special brand/type, but will be snitching several ideas of this forum.
If anybody recognises his idea in my build; Thank you! Your idea has made it over the pond...
Really; thanks! Great forum, with loads of nice stuff to be found.
Details of my to build/drawing:
Engine: Honda GX 160
Wheelbase: 890MM (yes, Dutch metrics.../25,4=...")
Rake: 30 degrees
Center to center bottom and top tube: 450MM
Handlebars height from ground: 890MM
Main tubes diameter: 26,9MM (better safe than sorry and a more ridgid look)
Sprocket front: 15T
Sprocket rear: 75-85T
If someone has any remarks, tips, or knows I'm way of in measurements, feel free to let it know.
For the build I have enough tools, like a mill, lathe, TIG & MIG welder, etc. Anything to make a nice bike.
Enough text for now, here are some pictures:
3-D software makes life a lot easier.
I bought 3 of those Honda GX 160 engines.
145/70-6 tires and 6" rims.
Getting a frame together. (at this point it seemed smaller as I imagined, altough I got some measurements from some threads here)
Head tube ready to accept some bearings I have somewhere in a pile.
Front/forks getting together.
I wasn't able to take a picture and sit on it the same time... (this is more comfortable as to a Chinese pocketbike)
More parts have arrived and drawing is getting upgrades. Sprocket adapter, axles, etc...
At the moment I'm a bit in a struggle with designing sprocket and disc brake adapters to fit my wheels. As I don't have the sprockets and discs yet. It has to be something solid, straight and easy to make.
Awesome build. You are pretty talented to be able to fabricate all that yourself- I wish I had a shop at my house to do all that! I'm envious!!!!!
Post finished photos please! Would love to see the finished product. And BTW love the Netherlands!
To measure RPM I'm using a "chinese" digital tach/hour meter. They are usable, but not accurate. Let's say it's a cheap piece of Chinese quality... If I touch the display with my hands, it shows 1200 rpm more...
So I want another rpm measuring device, and because I prefer a dial over digital, I ordered 2 different ones from ebay. A 0-6000 rpm (diesel) and a 0-8000 (2,4,6 and 8 cil) one. Just to see, which one would best fit or connect.
Because they probably need 12V I will add a small battery, which is practical for lights, etc, too.
I figured out all 3 engines I have bought, have some kind of coil, which makes AC Voltage. (Thread about that: https://www.oldminibikes.com/forum/honda-clone-predator/147545-honda-gx160-unconnected-wire-question.html)
I recently ordered a small rectifier/regulator for Briggs. And today I hooked it up to my Honda engine, to see if it would charge a battery. It did.
I will not be using this battery, this is just to see if things will work. I measured a charging current of 1,3 Amp.
I also fabricated a stainless steel chain/clutch guard, It just needs mounts to connect to the engine. I want a higly polish finish for it. That might take some time.
It's been to long since the last update. Not much news regarding the minibike. It is still running like it was in my last post. No fenders, electrics not installed. No paint, yet.
But, great times riding it! The engine never has any starting issues and it's always running great. The chain tension has never been adjusted yet, and might need adjustment soon.
Winter is over now, and I pulled it out the workshop and rode it for a couple of times and changed the engine oil.
Last year the twistgrip throttle came loose (sideways), I think it's a poor quality. I'm thinking to replace it with a thumb throttle.
I will fabricate my own fenders out of sheet metal soon, because the engine is covered in mud. Not to mention my face after I rode it.
And it needs some paint, too. Let the summer begin!
Fabrication of the fenders has started. All 6 of them... Yes, I need 6 of them, because we (me and my daughters) are going to build 2 extra minibikes. Much like the one that's currently running. More on that later.
Fenders; I couldn't find any fenders here in the Netherlands that would fit the tyre nicely. There are fenders for sale on internet, but they all have additional shipping and tax costs. Homemade gives more satisfaction, too.
I had some parts lasercut out of sheetmetal and made a mold to wrap the sheetmetal around, before tagging it.
They look fine to me, they just need to be welded.
The current minibike will be lowered. The top height of the seat is about 7cm (3") to high, so I will take a grinder and chop the frame. Maybe make some minor adjustments on rake and trail, too.
I also purchased some parts for the 2 new (yet to build) minibikes, including 2 new nice looking seats for just €42,50/each (=$53,-). It's length is 33 cm (13").
As I mentioned in my previous post, the seat height was a bit to high and I would lower it by chopping the frame.
It's height was to high, because of my mistake. When I made some drawings last year, I forgot the purchased seat also has some height. Well, now it's time to fix my mistakes and lower the total height (including the seat this time) with 3" to 24". The bike as it is/was.
Because I also want to make some other changes, I disassembled everything.
Cutting the frame and take 75mm out.
Plan is to make a small bend upwards in the 2 top tubes, under the seat. In a way that the tubes (when lengthened) can be welded to the "neck" again.(is that the correct translation?) In Dutch it's called "balhoofd". It's the "steering bearings tube thing".
Some other changes will be made to the frame.
I will cut the tubes out, which are located above the tires. They were meant to mount the fenders, but some flat iron will work even better.
Also the other tube that's located in front of the rear wheel will be cut out. It is of no use to me. To support the rearfender on the bottom I can make a small support coming from the engine mount. That will also be more handy when it comes to remove wheel-chain from the bike. With the tube in place I have to take the chain apart.
All together it will be a more compact minibike as it was, but it will be an improvement.
By now the frame is chopped and the seat height is about correct. Frame cut and clear the "old" tubes are not long enough.
Made a couple of new tubes to fit in front of where the seat will be mounted.
For the price they were asking this Honda GX160, I had to get it.
Frame chopped and welded.
Seat mounted on new fabricated seat brackets.
A small battery (12V, 2,9Ah), to power a small tachometer, will be located under the seat, as this seat isn't flat on the bottom there's room for it, without the battery (or a batterybox) being visible.
To replace the round gastank, I will make a gastank that will fit the frame. More on that later, as the parts have to travel from Arizona to here.
A new gastank will be made, but as parts haven't arrived yet, I have mounted the round gastank in the meantime.
The bike is rideable again. The lowered seatheight is more comfortable as it was before.
With the lowered height, I'm not able to remove the stock airfilter, without moving the engine.
The new gastank design and exhaust design can be seen in the video that can be found here.
The gastank capacity will be 2.8ltr, or 3/4 of a US gallon.
Gastank will be made out of stainless sheetmetal (1,5mm thickness). Cut out of leftovers from work. I choose this design, because it's more narrow and leaves more space above the engine. Overall it will give a cleaner look.
Today I started with changing the rear tire with the front tire. Now the rear tire has some knobs on...
While changing the tires, I took the cheap clutch of, to inspect it. It all looks ok and I oiled the bushing a bit. Also made some other spacers for the front- and rear hub assemblies, as the rear discbrake was touching the caliper.
After everything was mounted back on I took it out for a ride. Link to video.
I've also welded the stainless sheetmetal for a new gastank.
All sheetmetal parts for a new gastank.
TIG welded everything.
Filler necks, caps, nuts and gastaps are parts that still need to arrive.
Awesome build! Very nice work, I like it a lot!
Our side of the pond definitely needs more minibikes I've been trying to convince my friends to start building too but so far no luck, they love to take mine for a spin though.
Btw, Nederlander here too but living in Sweden, I moved here 18 years ago.