My biggest question is there an adapter of some sort that i can get to add front disk brakes to this 26" Mongoose Hex Mens Fitness Bike, Mongoose Mens Bike, Matte Blue, 26" Mongoose Bike

I'm doing something to this bike, and i'd prefer to have stronger brakes.

Also, what can i do about getting stronger rear breaks? In this case i cannot use disc brakes in the back.

I sense you're going to do something no one here would approve of.

Also, it would cost more than that whole bike is worth.

The myth that disc brakes are somehow more powerful then rim brakes is just that -- a myth.

If your brakes are inadequate, odds are it's a question of adjustment and proper set up, and not because they're lousy brakes.

Also, you can often improve brakes with better shoes, such as Kool Stops.

However myth or not, adapting disc brakes on your bike isn't an option, so you might as well focus on what you can do.

I bought one of those motorized bike kits for a multitude of reasons.
1. It will be my transportation to work.
2. I work in retail, and walking into work sweating through my clothes (even though i've changed into approved uniform rather than wearing my uniform) has gotten me in trouble. I sweat alot. like...enough that i can sweat straight through denim jeans.
3. It only takes me 15-20 minutes to ride the 12 miles it takes me to get to work on my Fuji road bike, but with summer approaching and my previous problem mentioned..i have to do something about it.
4. No public transportation in my area. the closest bus stop is in the parking lot of my employer.
5. My car not only costs too much to drive, but needs to be fixed.

If the bike is new, the braking will probably improve as the pads wear in.

you would need to change the fork and wheelset to add disk brakes to the front.

I dont think you can add disks to the rear if there is no mount on the frame itself.

You will not have greatly improved braking capabilities by doing this.

just replace your pads with some kool stops.

your best solution is to bring a change of clothes to work w/you, get there 15 minutes early so you can change and clean up. dont forget the antiperspirant/deodorant.

36-48 MPH!
Why aren't you a professional?

I wouldn't bet on functional brakes.

Some entry level bikes these days come with @#$%^& spring loaded brake noodles so riders who neglect to brace themselves don't end up on the ground with their health insurance company recovering their expenses with legal action against the shop, bike company, etc.

Unfortunately it may not be possible to bottom out that spring and apply full brakes before running the levers into the bars.

If that's the case a normal noodle can make a huge improvement.

Because his "boss" doesn't approve of it... Tough life: no nearby public transportation but can ride faster than my car.

Its mostly all downhill. There are also a few larger/longer hills that i can get close to maxing my bike's gearing out. (i have a fuji Absolute 3.0. Probably nothing impressive)

Also, in relation to the front wheel needing to have mounts...I knew that part. I was planning on changing the forkset anyways.

Your fork doesn't appear to have disc brake tabs.
Your frame doesn't appear to have disc brake tabs.
Your wheels doesn't appear to have disc brake hubs.
With a $ 160 price tag on the complete bike, and all the parts you'd need to buy, I'm struggling to see a sensible way forward to achieve what you want.
Why not start by staying with rim brakes, and work your way through modest upgrades?
-Salmon pads
-Well routed, high quality cables
-Maybe some brand levers and v-brakes. I like Avid Speed Dial and their Single Digit brakes. But Shimano XT have a good rep as well.

Heck, even something like the Magura hydraulic rim brake Rim Brakes*| MAGURA might be one of the least silly ways out for you.

Getting a rear disc brake might not be too hard, if you can get something like this to work: Robot Check

But why a motorized bike?
Apart from the possibility of pedalling in case of running out of fuel, I don't see the point.
Wanna go brrm, brrm, get a scooter or a moped.
Less risk of flats, less maintenance, built for the task.

You really think you are averaging 36-48mph?

As for the bike, don't put the money into it. Totally not worth it in the least. Kind of like putting an expensive paintjob on an junky old Yugo car.

Why were you planning on changing the fork?

Your v-brakes are just not in proper tune otherwise they would stop just fine.

there is no place to mount any other brakes than what is on there , you need to go buy a bike with disc brakes on it in the first place .

Trek 3500D is a good bike.. But you wont get them at wally-world..

If you already have the bike, and already have the kit, might as well go ahead. Post the kit here so we can take a look. I think you'll be disappointed in the result (you'd get to work smelling like gasoline) but it could still be a fun project.

Also, top speed on one of these things is slower than pedaling your Fuji anyway - 48mph, wow.

Bingo! There are many layers to this and each one is suspect. Here are a few:
Even motorized, the OP will spend at least the same time in the heat, thus sweating.
Brake "power" is limited by tire traction, which rim brakes can already exceed.
A used moped would be much more cost effective.

I could see using Shimano Deore brakes and levers with Kool Stop dual compound brake pads. I wouldn't mind knowing what kind of horsepower you have though. Interesting.

@dabac i can do something with the brakes. The intention of the motorized bike is that i have tons of 2 stroke motor parts. From pistons to expansion chambers to CDIs. fuel cost is low, considering the trip is 12 miles. 24 there and back i'll probably be on a half a tank. Not too bad.
@bobotech In relation to my average speed, i believe so. Its all down hill save for 3-4 straight aways. On some hills i can nearly max the gearing out on my bike but have to slow down early. In relation to changing the fork, I want something with shocks, but thats later down the road i guess.
@DiabloScott I don't believe i will smell like fuel considering the exhaust will be way behind me. but keep in mind again, 75% of the trip is downhill.
@AnkleWork Once it gets warmer i sweat just sitting in a chair. Once i start pedaling and really going at it (wow think of the coincidence of the topic) i start to sweat to the point that i literally look like a rainstorm when i get there. I will definitely sweat less not pedaling.

Right now i just need to break the motor in before i start building the motor. Once that happens it will change.

I disagree. I think there are ways that one can improve the overall function of rim brakes but to say that they are on par with hydros is, excuse me for saying so, more of a denial than anything else. My 10 y/o agrees.

OP, what exactly is the problem with your setup? I have a '97 Schwinn HG that is equiped with both a rim brake in the back and disc in the front. I found that adding a brake booster significantly improved stopping power.

Black Cycling MTB Bicycle Bike V Brake Cantilever Brake Booster with Screws | eBay

Ok, that explains the engine, but why start with a bike?
It's a lot less rugged frame than, say a scooter or a moped. Expect fatigue cracks fairly soon, particularly if you start tuning the engine. And you still have the issues of brakes and suspension to deal with.

I could have gotten a scooter, but after riding one i didn't really like it. the ones that can be bought in the area i live in are kinda low quality (in relation to price range) and to be honest, i don't really need to go more than 40. the speed limit on the roads i'll be riding on are between 30-40. when it comes to tuning all i want is to be be able to power up hills without slowing down. I've abused bikes, and hardcore. I've never had any frame issues before, but i will upgrade the rims eventually. Once i'm able to afford higher quality 29s.

But isn't the bike a 26"?
W/o disc brakes, fitting bigger wheels is a hassle.
And while 26" MTB frames usually have room enough for 700c wheels with skinny road tires, fitting a 700c AKA 29er rim with the kind of tire That'd make sense on a motorized bike seems like quite a stretch.

the frame is close to the size of a 26 inch bike frame, but came with 29 inch tires.

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You have typo in your link, it IS a 29er bike. What are you hoping to gain from another set of wheels? In bicycles, "better" often means "lighter", which wouldn't be that interesting for you.