The Not So Cool Mini Buggy Build

[n1kogr]

Let me introduce myself. My Name is Nick im a 16 year old gear head... Iv'e been working on minibikes to dirt bikes to atv's for a while now and loved every second of it! Last year i sold off all my projects for my biggest one of all, a wrecked 97 BMW m3. (here is the build thread to that if anyone is interested http://www.m3forum.net/m3forum/showthread.php?t=353167&highlight=slow+build ) The 90's m3's have always been my dream and working hard to get one has really made me feel good about myself and also learn a great amount. But in the back of my head Iv'e always wanted to build a buggy and Iv'e finally brought myself to do so.

i started this project a while ago so this is a half way build but still so much to do.

i originally bought a duromax 16hp with e/s but soon found out i wanted gears plus a reverse but i didn't want that motor to go to waist so i got a 1986 trx125 from a friend for $20 that i am using for parts and also for its trans. Iv'e never seen anyone attempt this but i have always thought about doing it. Stay tuned and more pics and details to come tmr.

 

[fowler]

if i may make a sugestion

use the swing arm off the quad and put the enigne in the frame seperate

u will get much better performance over rough grond and it will be alot healthyer for the engine

also not so important but id lose the seat based on exess weight
iv got an old office chair and it is comfy and very light also it allows better airflow to the engine (not important unless motorbike)

 

[TeamCheap]

Interesting project.

The front end just looks wrong its those spindles ideally you'd want the spindles tucked up into the rim for better steering and less chance of them bending or breaking (leverage) if/when you snag something with the front end.

The plexiglas should go its an offroad vehicle and you'll be wearing a helmet and goggles when riding it right RIGHT LOL.
If you want a windshield atleast use LEXAN you can get it at the hardware store but it is a bit more expensive but is far stronger and safer than plexiglas.

Put some bigger tires on the back and just run it with the engine and have fun rather than try to utilize the trx 125 trans.
If that trans is good you might be better off selling it and with some other money buy a forward/reverse trans that you could use on that buggy.That forward/reverse trans is setup for use with a torque convertor so that would cost even more though.

 

[Doc Sprocket]

Interesting, indeed. That looks like a dead axle, which IMO is a total waste with everything else you've got going on there. Can I assume a live axle conversion is part of the plan?

How are you going to make the mechanical connection between the engine and the bike tranny, and what will you be doing for clutching?

I agree with TeamCheap's comments regarding the frontend. The scrub radius is pretty
raunchy, but it might be a difficult fix for you. In terms of performance, it might be tolerable, but I'd be too worried about breaking things. Lots of leverage there, in the wrong place.

With regards to the bike gearbox, I actually would like to see it implemented. It's been discussed on paper a few times, but I've never seen it done. It has good potential, but see above comments re: mechanical connection and clutching.

 

[TeamCheap]

If the bike engine has a dry magneto area then just remove the cyinder and connecting rod and cylinder studs and plate that area off then make a sprocket adapter to go in place of the magneto and drive the trans with the engine and use the trans clutch/gears as you would any other gearbox.

If that engine is a two stoke it would need oil in the crank shaft area.

If I remember the little honda 50cc were dry magneto but my 300ex is a wet (oil bath) type you just have to see what type it is but a dry one shouldnt be hard to do.

 

[n1kogr]

I see what you are all saying and i thank you for the helpful replies. First ill start with the swing arm idea. The 86 trx125 had no suspension what so ever so im just going to try it out like this and see what happens.

If you look at the axle there is square tubing covering the whole thing. It is a live axle which i was surprised about but i have my new 1" axle on order.

The engine is basically already connected to the trani all im waiting for is my sprockets i ordered as well.

For the spindles i dont like them at all so im thinking of just using the ones from the atv and see if i could hook up the front brakes on those as well.

For the plexi glass... yea im not using it if you look closely its already broken. i will wear my motocross helmet and goggles when i romp on this as i have had too many stupid mistakes lead to be bleeding on the ground...

As for the seat it is surprisingly really light so im going to try it out for now and if i have any problems ill just yank it and find something else.

Lastly in one of my pics you can see the atv standing up. It has those monster back tires which i am going to use i just need my axle with by hubs to come in.

I hope i have answered all of your questions and i will also get alot more pics up today.

**note for this project i am surprisingly not looking for speed i just want torque and something cool to put around on.

 

[TeamCheap]

I like the seat myself looks comfy. lol

Yeah those rear atv tires would be good on it.

I put this together just to putt around on and it came out OK.

Its an old blaster with a 200cc 5-speed 4-stroke electric start chinese engine stuffed in the frame.

 

[n1kogr]

I like the seat myself looks comfy. lol

Yeah those rear atv tires would be good on it.

I put this together just to putt around on and it came out OK.

Its an old blaster with a 200cc 5-speed 4-stroke electric start chinese engine stuffed in the frame.

That looks great im sure it still has some good power. i also like the blue chain... whole bike looks clean tho

 

[n1kogr]

Ok so i got a little bit of work done today plus the pics of how i am going to connect the trani to the engine..

I put a few reinforcements here and their on the rear end of the buggy but they arent pic worthy...

I started on the front end today and decided i had to move the steering rack

This is where i am going to drill my new mounting holes (tip of screw driver)

For the steering i need to lengthen the arms 1" on each side by cutting it and inserting this long bolt and welding around it.

I also need to make new mounts for the spiderbox front end because i choped of the old ones to fit in the rack i was thinking something like this

And this is the new look of the front end with the new spindles

 

[n1kogr]

Another problem is since all of the weight that has been added the rear shocks are way to soft would this rear shock off a kx 80 help or should i remove the shocks and make it a static rear end untill i find stiffer springs?

And this is how she sits for tonight.

*Note all the rust in the pics on the front end is just surface rust nothing serious.*

 

[Doc Sprocket]

Time for some constructive criticism, if you don't mind. The welds I see in the first several pics are not at all sufficient, and will fail. You'd do well to practice on some scrap, and then grind off and re-do the previous parts. You need a lot more heat in there, there's no fusion/penetration there.

Can we get some more detial on how you have the jackshaft coupled to the bike tranny shaft?

 

[n1kogr]

Yea ik im going to re do those welds no worries. the way i connected the jackshaft was i took the pull start recoil whatever you want to call it and welded on 3 1" locking collars with a key way.. it was pretty simple just a pain to get it as centered as i could

 

[Doc Sprocket]

Interesting. Did you orient things that way for a reason that I am missing? Just thinking out loud here, but would it not make sense to put the engine on the left, and the tranny off to the right?

Either way, I hope this works out- I really want to see this happen.

 

[n1kogr]

If i put the tranny on the othe rside then i wouldn't be able to use this simple jackshaft method i have.

 

[Doc Sprocket]

Couldn't you just run a straight, short shaft right from the engine into the tranny, and use the bike's factory clutch? Or- run a belt or chain from the engine to the tranny with no shaft at all? I'm not ripping your design apart, just trying to understand it.

 

[n1kogr]

i am using the bikes factory clutch. i am putting a 13t sproket on the jack shaft and a 13t on the engine then just hook up the honda to the axle.. maybe once i get my axle in and put everything together it will be easier to understand

 

[n1kogr]

I got my steering done today

heres the front end...

The front rims will be spun around so they cover the spindles. The reason they are like this is because i never cut off my old spindle brackets so the wheels rub ill get those taken care of soon.

I ordered my 5/8 rod ends for the a arms so they will be as strong as can be. This weak little setup was just temporary. i was also thinking of extending it 4" at the swing arm links for more clearance. I have also decided im going to make my role bar bigger and center/ straighten it as you can see its mangled from the last time i flipped it. Enjoy

 

[TeamCheap]

keep plugging away at it you'll get it.

I really like that yerf dog front end I'd like to see that setup in the rear as well but it would take a lot of work.

You'd have to put the lower arms on top and the top on the bottom so you could still use that shock mount then you'd have to come up with a few U-joints and shafts and rear hubs but it would be an awesome ride then.

 

[n1kogr]

I was thinking about independent suspension in the rear as well but ill think about that stuff once i throw a real motor on here. Im really thinking of putting a yamaha sr250 on this buggy once i beef it up...alot!

 

[TeamCheap]

I was just looking at BMI's site and they sell two Yerf dog front end kits, one with spindles and one without, the one with is $285 but the one without is only $150.