midi maybe not a mini bike ideas

[Kart_the_Unicorn22]

Okay,
lets see if I can say this in as few paragraphs and not get to droning on. I am looking for some ideas to bounce off of people with pictures to come as we build.
I want to build a medium sized bike. I'm looking at the 8hp 301cc model(open to others) not quite a mini bike with a engine from harbor freight and custom suspension front and rear, I have access to a lot of metal working tools and will fabricate almost all of the frame and handle forks, engine mounts etc. on my own with recommendations welcome if it will save me a lot of time.
I have metal bending equipment. Plasma cutters and shop guys who like beer and a lot of free time this winter.
here is where I say the problems but I feel like there just more things to work out with my build that I need guidance with.
1. I am not a very small person lets just start that off I am 6'3 and weigh roughly 250lbs this is my first dilemma.
2. I want something super low torqued for hill climbing near where we hunt on trails that I cannot take atv's and trucks on, we have trails open but for motorcycles.
3. I am looking for something with ground clearance and suspension front and back. something in the 5"+ range (think something like a fat cat from the 80'S)
4.Also i was teasing the idea of a reverse style trike for this concept as well but that might be getting crazy

what I need help with is basic torque converter info I want something not fast per say 15-20mph max speed but really low torqued(even if fabrication is needed to assist this) I want to be able to climb hills and assist with legs if needed.
sprocket and chain info I want ease of repair for tool kit I am packing for the chain and what not. This is for a back country situation accessible by motorcycles hauling single wheel trailers mostly....
tire suggestions medium size width wise...

I want to thank you ahead of time we start frame work tomorrow barring weather issues

 

[madprofessor]

The TC is something I can speak about. Regardless of your torque needs, I'd get a 40 series driver/clutch pulley for the driveshaft output, and run a separate jackshaft for the driven pulley. I'd then have a second jackshaft to be run by a chain from the TC jackshaft. Your torque will begin with a large sprocket for input to the second jackshaft, and a smaller sprocket for its output. Then the chain from the second jackshaft's smaller output sprocket will run to the axle's even larger sprocket. You can vary the sprocket sizes to create any amount of torque you want. The pictures below (build was in progress) show what is a 6:1 gear ratio on a 30 series TC on a backplate, it's now changed to 9:1, but I could make it 20:1 if I wanted to by changing sprocket sizes. Talk about torque, the thing would probably do wheelies.

 

[Denny]

On the GoKart Supply website there is a gear ratio calculator that will be of huge help to you. I have to agree with the 40 series CVT. Also I think I would go with a bigger engine. Either the 420 or the 445. It will give you electric start and also the ability to run a led headlight.

 

[Willie1]

On the GoKart Supply website there is a gear ratio calculator that will be of huge help to you. I have to agree with the 40 series CVT. Also I think I would go with a bigger engine. Either the 420 or the 445. It will give you electric start and also the ability to run a led headlight.

That chart is a good starting point - but . . .
That chart ASSUMES the clutch has locked up at zero slippage.
Toss in a CVT set-up and the chart doesn't adjust for belt slippage or the driven pulley "shifting" -
if the CVT doesn't shift up, the top speed will be way low.
Would be nice if they also had one for a 2nd tier of ratio adjustment, like jackshaft equipped toys.

 

[gmotz]

If you check out the 'mike festiva' user on youtube, he built a really nice little XR100 with a predator that i might try to replicate. Used dirtbike rollers, especially like TTR125 and stuff are dirt cheap, for 200-300 bucks you can get wheels, suspension, all kinds of stuff that would cost way more if bought separate.

When i have people over to ride dirtbikes and four wheelers around my property, the clutch/shifting thing always throws people off that aren't used to manual transmission, so i was thinking it would be fun to have something torquey and automatic that people could just hop on and ride.