2 stroke vs 4 stroke

[Jason A]

Hey guys, first post for me !
I'm looking at building a my first motorized, and I have two totally different kits in mind.
Either a 66cc 2.75 HP two-stroke, which costs $119 USD, or a 49cc 2.5 HP four-stroke, which runs $199 USD.
Both are (obviously,) not super great engines, but I'm on a budget, just looking to have fun. Don't need practicality, as this is purely for fun, and I can ride on basically any terrain, (paved, gravel, grass, dirt, etc.)
Which of these is better, and is it a good choice? Also, is a 44 tooth sprocket ideal for these varied conditions?
Thanks for fielding my newbie questions!

P. S. Other motor recommendations are welcome, too.‎

 

[butre]

2 stroke if it's not for daily use.

 

[Purple Haze]

The 4 strokes are better for reliable, day to day tranportation, are more quiet, and less messy and smelly. That said, 2 strokes make more power, are cheaper to buy and work on, and their simplicity allows for easy mods. Aftermarket parts are plentiful and reasonably priced. Plus, they just look cool! I don't care for the lawnmower engine look of a 4 stroke. The fun factor alone makes this choice easy. The gearing is a personal choice, with terrain and top speed factors. I ride in hilly terrain, and use a 48 tooth sprocket to good effect, it'll pull your head off, but on the street it only runs about 25 mph.

 

[bakaneko]

For fun go with a 2-stroke for all the reasons purple and butre has mentioned. Also, the HP comparisons (2.75 v 2.5HP) you have listed isn't entirely accurate. The stock 2-stroke and modded one has way more power than the 4-stroke stock. Also, you need to consider the bike you are using too. A 4-stroke is a wider and taller engine. Price conscientious and fun purpose wise I would go with the 2-stroke.

 

[libranskeptic]

dont trust my numbers, but some ~philosophy that may help here:

you dont mention weight, a key factor, but the effect of savings depends on total bike load - u plus the bike.

this favours 2 strokes - no valves and fancy head.

2 strokes are maybe 30% more powerful in theory - double the power strokes

either engines power is huge. 1 hp is ~730 watts? i think, and thats a very decent ebike. an ebike motor based on a common 25cc brush cutter motor is about that i think - small, light, cheap, mass produced quality & reliability

single cylinder motors are inherently unbalanced & sound & feel crappy. done well, a 4 stroke will sound and feel much calmer to hear and ride.

for suspension, just use big, not too hard, tires

chainguard is important

a hydraulic clutch sounds good if they exist - comments?

this seems very cool



Motorized Bicycle with Jackshaft Kit - ie - 7/8 gears

 

[Jason A]

Dumb question, I know, but will a normal chain guard work? I see no reason why not, but I'd hate to order one and find out it doesn't fit...

 

[bakaneko]

I haven't seen one kit that did not come with a chain guard. Also, the chain guard is optional. I rode 1500+ miles with no chain guard. For 2-strokes, I can imagine the chain guard adding a nasty rattle. I don't wear shoes with laces so no danger there and spray chain protector on my chain periodically.

 

[Charles Laypool]

I would stay away from the 199.99 4 stroke chain drive the gear reduction is not enough i built a fat tire 4 stroke for a customer and he burned the clutch up in 3 hours of use with a 26inch tire and 44tooth sprocket its geared to go 45mph and the engine cant do that so ur clutch slipps and slipps till u overheat ur bushing and seize the gear box get the 7g(ghost racer)if u favor 4 stroke is goes 26mph with 26inch tire and 44tooth sprocket iv used it for 2 yrs and replaced only a belt

 

[libranskeptic]

re chainguard, a chain on both sides sound fraught to me, the second one being far more treacherous.

it seems right it should come with a kit

given the drive is usually on the opposite side, a normal guard seems unlikely to fit.

if u r not swapping sprockets for gearing, why not. A major bonus with IGHs (which suit a guard), it was pointed out to me, is dead simple chain lubing thru a hole in the guard after a big ride in the dirt.

 

[45u]

When you run wider tires you are putting more wasted HP to the ground which will put a lot more strain on the motor and clutch this is why I like to say with a tire a little over 2 inches. The reason my first kit was a 2 cycle is because they make many hop ups for the 2 cycle and all most not for the 4 cycle. I will build a 4 cycle one day.