UMT- Utility Motorcycle Tractor

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Tatras86

New Member
#1
#1
So let me quickly introduce myself. I'm from Slovakia (Europe) toolmaker by trade and last 5 day totally addicted on Minibikes. I never know that something like that exist and now I'm all over this "madness". So that's me :thumbsup:

Now get to the point and that crazy topic. Why I love minis..... because they are simple and soooo awesome. Why I need one.... well because I need one :laugh:

So now to the topic. I need something like this

https://www.youtube.com/watch?v=JuuO_17YuTA

I want to build it by myself from scratch to my specs. as it will be use in logging business as I'm professional logger and also I want to used around the farm because I'm also the farmer as well. I live in very hilly country and I'm very heavy (someone may say FAT) around 320lb an 6'5" so I need the powerful strong machine to move around with me and with some equipment so if 20-30 mph will be the top I don't care at all. What I'm looking for is low-end torque and nice slow precise handling over the rough terrain.

After the readings over the forums and watching the vids I start to understand what is what and putting things together on the paper.
But as my UMT or MotoTractor is very different from most of the other minis I decided to join OldMiniBikes forum and I hope U will help me to get this idea rolling.

Thanks for now and sorry for my english :smile: you know as I'm not the Englishman....

If there will be some interest in this than I will get some details of things I've got in my head
 
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JKautoFab

Active Member
#10
#10
if you have rough terrain, i would go with the biggest tire on the back you can push. like a little tractor tire. there are some tote gotes in that thread setup like im talking about. id go with a multiple gear reduction. would be neat to have multiple gearsets, you could simply swap a different chain for a different gearing for heavy pulling or higher speed. with a torque converter of course!

i wouldnt use a crappy little ball joint for the trailer like they did. i was going to use a steering joint from a honda car to make a trailer for a bike.

personally i would find a big electric start sideshaft, with recoil start for backup. i dont like pull starting things if i dont have to...

no suspension does make it simpler... but i like comfort. for the front, im a big fan of the connected leading link fork on any fat tire bike.

being a utility, i would make sure the steering could go almost 90 degrees so that you can turn around almost anywhere. pushing a bike backwards is no fun, its damn near impossible if you are pulling something!

just my ideas and opinions. ive gone minibike mad myself. its a disease. they multiply! be careful!
 
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Tatras86

New Member
#11
#11
JKautoFab said:
if you have rough terrain, i would go with the biggest tire on the back you can push. like a little tractor tire. there are some tote gotes in that thread setup like im talking about. id go with a multiple gear reduction. would be neat to have multiple gearsets, you could simply swap a different chain for a different gearing for heavy pulling or higher speed. with a torque converter of course!

i wouldnt use a crappy little ball joint for the trailer like they did. i was going to use a steering joint from a honda car to make a trailer for a bike.
Click to expand...
:scared: You are mind reader.....:thumbsup:

So I was thinking about 2 different set ups ;

1; if I get loads of $$$$. Honda gx 390/ subaru robinn ex40 + comet 40 converter + 25' fat tyres with 2 different gearings one 8T to 114t for offroad second 10t to 57t for more onroad set up

2;if I get less $$$ honda gx200/ subaru ex21 + comet tav withs same gearings as above

Please don't laugh I just find some gear calculator and do a little play with numbers and I ended up with this which may be toooo extreme. So I NEED your advice on this.

Another thing I want to keep motor stock no mods.

Anyway thanks for warm welcome on OldMiniBikes:thumbsup:
 
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Tatras86

New Member
#13
#13
Well I found that Pak Jak mini maxi bike and Im sold on that Is there any tech info about them cause I couldn't find any. How big is rear tire? Gear ratio? .....
 
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JKautoFab

Active Member
#15
#15
go with the honda you wont ever regret it

if you have two wide parallel jackshafts it would be easy to have the multiple gearsets lined up. could fit 3 easy in the width of a mini

the pakjak is cool, are you looking at the dual rear wheel one? or the giant back tire one?

ok i just re-read what you said, i think you are talking about the single then. i wouldnt worry about what the pak jak used if you are building it. i would start with what you can easily find and easily replace! ive seen some 7 inch skinny mini bike tires and im guessing they are gonna be about impossible to replace bc i do not know of any current 7 inch skinny tires being made

id go hit up some farmers for an old tractor wheel/tire. something too worn for their use might be plenty for yours
 
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Tatras86

New Member
#16
#16
I'm leaning more towards Subie but in this class they are both great engines. As I said all depends on money.

Yeah that big tractor tyre one looks awesome. And now I'm thinking to make some sort of gearbox to make it easier and quicker go from offroad to onroad..... hmmmmmmm now I wish I never found this forum.......... this project will be expensive :laugh:
 
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JKautoFab

Active Member
#18
#18
if you did the gears in a reversible pattern, like one set being 15 tooth front, 40 tooth rear, and the other being 40 front 15 rear (ignore my actual drive ratios im just putting in numbers) you could carry a single chain that would swap between both. making a gearbox to have both available on the fly, i would think might get expensive...

another option, which may suit your needs better, would be to use a peerless transmission that is used for lawnmowers and lawnmower racing. This would also allow you to use a lawnmower bottom shaft engine that is probably electric start. instead of using lawnmower belts, you can simply use a centrifugal clutch and chain from motor to transmission, you would just need to change the top pulley out for a sprocket. the output on the transmission is horizontal, and the transmission also has its own brake (on some models not all)

this would give you 3 speeds and reverse. some of them even have 5 speeds but those arent as common. if you are rocking that big back wheel and are pulling a trailer, that reverse would come in real handy!!

only thing i dont really know is, are riding lawnmowers common and easy to find in Slovakia? here they are like weeds, lurking in just about every yard!
 
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Tatras86

New Member
#20
#20
That peerless transmission looks good but hard to find over here. Something that small with reverse sounds great.

Could anybody educate me on final gear ratio? Say for example from TAV to 1st. jackshaft 1:2 than from 1st. jackshaft to 2nd.jackshaft 1:4 and than from 2nd. jackshaft to sprocket 1:6 what will be the final gear ratio?
 
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