Check out this engine

[mark20]

Yup, that was my first ever motorized bike kit!

Beat the crap out of that engine, daily drove it from school and back and where ever I went, from -32f to 100f, it survived it all! Even used it in my final science project about 2 cycle motors lol.

Probably had close to 10,000 miles on it before I sold it off to my buddy (who still rides it from time to time)

The only upgrade id do to it is a 36t sprocket and an NGK B6HS spark plug.

Great motor with plenty of power and AWESOME durability! The only thing that crapped out on me was the CDI box, which I blame my younger self for leaving the bike outside in snowstorms and rain.

 

[Cannonball3]

Its a 40mm long rod. Other specs you are reading is for the smaller 50cc version. The horse on the cylinder is Im guessing for Flying Horse. I just gave away a bike with an old FH engine that has run for years. Vibed a good bit but never broke. This new engine is well designed with open transfers. Piston is completely out of the exhaust at bdc.
Also says chrome plated bore, but looks like a hard coating of some sort.

 

[Freddy Snottgrass]

You guys are right, this is a nice little engine. I hope I am not speaking too soon, I wanna say this is the best out of the box (performance wise) engine I've gotten. Might become my precious.

 

[DAMIEN1307]

Might become my precious.

Hahahahahahaha

 

[Karl Snarl]

You guys are right, this is a nice little engine. I hope I am not speaking too soon, I wanna say this is the best out of the box (performance wise) engine I've gotten. Might become my precious.

I let my friends ride my bike with these motors on it. They haven't killed it yet. An let me tell you, some of them suck at MB'n. Just a great little engine for the price.

 

[Cannonball3]

Heres my NR. Its on a build what you got bike. Painted the cylinder to give it some character. Notice it runs a fuel pump
since the carb and tank are nearly at the same level. Its running a G2 reed set up now. This is my go to ride to run errands, and go places. Never given an issue. Toying with making it a Mineralli. Finally got my Smolik order.

 

[Nickt919]

I checked the compression on my nr80 today. Thought it was pretty high….Just shy of 210 psi.

 

[Freddy Snottgrass]

Notice it runs a fuel pump...

How does that work? I see it there at the base of your cargo rack.

 

[⚡§H🎯©️k3®️J⚡]

Bikeberry.com has the best engines. And the best built in gas frames. But order your mag wheels off ebay. You might also wanna check out phatmoto.com. the fat tire bike is a beast off road

 

[Karl Snarl]

I checked the compression on my nr80 today. Thought it was pretty high….Just shy of 210 psi.

That should be around 150psi. Any higher and you reduce engine life by beating the crap out of the bearings. The upper con bearing is probably going to be your failure spot, maybe the bottom. I'd bet on the con rod bearings being what kills it when it dies.