4-stroke engine fit on mountain bike...

[plamb]

Hello,
I'm starting my first build and I'm trying to do something not very common from what I've read and seen.
(Bike picture below)
My bike seat tube lenght is 550mm, steel frame. Disc brake only on the front wheel, hardtail.
I want to fit a Mitsubishi GT241 4 stroke 80cc engine, I'll be buying new so I want some advice from you guys.
The Mitsubishi engine dim. are : L-274 mm / W-303.5 mm / H-285 mm / 9.5kg
Anyone have expirience with these engines? Should I look for something else? Do you think it will fit on this frame?
I want a quality 4 stroke engine for offroad.
Thanks.

 

[mark20]

Hello,
I'm starting my first build and I'm trying to do something not very common from what I've read and seen.
(Bike picture below)
My bike seat tube lenght is 550mm, steel frame. Disc brake only on the front wheel, hardtail.
I want to fit a Mitsubishi GT241 4 stroke 80cc engine, I'll be buying new so I want some advice from you guys.
The Mitsubishi engine dim. are : L-274 / W-303.5 / H-285 / 9.5kg
Anyone have expirience with these engines? Should I look for something else? Do you think it will fit on this frame?
I want a quality 4 stroke engine for offroad.
Thanks.

i dont think it will, it will require a bit of modifcation (such as hitting the seat tube in a bit)
for a more simpler build, id do hs142, they are smaller and will fit most bike frames (take a 10in by 10in cardboard cut out and see if it fits in the frame)

 

[darwin]

Plamb, do you have a link or pics to that motor? Never seen a Mitsubishi 80cc 2 stroker. Nice bike.

 

[plamb]

Hey, thanks for the responses.
darwin, thanks, btw the engine is 4 stroke not 2, I personally don't like 2 strokes for many reasons but here is the picture (below),
mark20, if I remove the factory exhaust, air filter and fuel tank, the size and dimensions between the hs and the mitsubishi look kinda similiar, do you think it will work, or it's wishful thinking?
Specs from the site: http://www.mhiet.co.jp/en/products/engine/engine/gasoline/four_cycle_engine_gb_series/gt.html
Picture of the engine:

 

[mark20]

Hey, thanks for the responses.
darwin, the engine is 4 stroke not 2, I personally don't like 2 strokes for many reasons but here is the picture (below)
mark20, if I remove the factory exhaust, air filter and fuel tank, the size and dimensions between the hs and the mitsubishi look kinda similiar, do you think it will work, or it's wishful thinking?
Specs from the site: http://www.mhiet.co.jp/en/products/engine/engine/gasoline/four_cycle_engine_gb_series/gt.html
Picture of the engine:

Thats basically the same engine as a predator 79cc. It should work if you remove everything (key word here is SHOULD) you can get a 60$ ebay torque converter and get a shaft step up adapter for like 10$ these engines are small enough that it might work with that frame (but still would require some modifcations). Id recommend you get a beach cruiser style frame or even a bigger framed mtb (like a giant recon size xl)

Do you have a welder? Becuase you would need to weld up a custom motor bracket.
Plus reinforce the bike frame (79cc is a lotta motor for a bicycle)

All therys here.

If you want a simple bolt on-ish 4 stoke motor kit a hs142 is calling your name. They have plenty of power to go offroad and on road. (I know becuase i have one, never failed me yet!)
Heres a link

49CC 4-Stroke GAS PETROL MOTORIZED BIKE BICYCLE ENGINE MOTOR KIT Scooter | eBay

Find many great new & used options and get the best deals for 49CC 4-Stroke GAS PETROL MOTORIZED BIKE BICYCLE ENGINE MOTOR KIT Scooter at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[Sidewinder Jerry]

Another important question is are you building a shifter or single drive system?

 

[plamb]

mark20, my uncle is a construction worker and he can weld pretty good, what is the motor bracket for, mounting the engine? I might go with your advice for the hs kit. It's my first build and I really don't want to mess with the frame on my bike. I'm just not sure if 50cc will be enough for me, also the chinese motor...
Thanks for the information!
LR Jerry, single speed.

 

[mark20]

mark20, my uncle is a construction worker and he can weld pretty good, what is the motor bracket for, mounting the engine? I might go with your advice for the hs kit. It's my first build and I really don't want to mess with the frame on my bike. I'm just not sure if 50cc will be enough for me, also the chinese motor...
Thanks for the information!
LR Jerry, single speed.

It's plenty for me, i regularly go on old fireroad trails and muddy atv trails when i go fishing. Ive never had the thing bog down on me. Starts up 2-3 pull every time!

Im 6ft 3 and around 190lbs for reference.

And a motor bracket is what attaches the motor to the bike

 

[plamb]

Alright, I'll go with the HS kit. What's the best size sprocket for a very hilly area?

 

[mark20]

Alright, I'll go with the HS kit. What's the best size sprocket for a very hilly area?

I found that the stock 44t is pretty much perfect for the stuff I do, (about 40/60 on road, off road) but id try it out and see if you need more. Id wouldn't go higher than a 50t as then you top speed will be drastically affected.