2 vs. 4 Stroke...

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BarelyAWake

New Member
Jul 21, 2009
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The "comfort" was mostly a reference to the style of build I'm considering, tho as a four stroke is typically quieter (depends greatly on exhaust system) and is prone to less vibration (generally lower RPM use), there's a greater potential for general "comfort" - but I do feel the need to point out that a two stroke can achieve similar results if the build is planned with that in mind (proper silencer & gearing).

Distance... well, although I'll be the first to defend the much maligned 2smoker - it's also true that sustained, high RPM use isn't it's forté, if we're talking about wide open throttle for hours there's the potential for excessive wear and overheating. They're particularly well suited for sprints, like heavy traffic or off roading - dirtbikes are a good example.

The four stroke is a better candidate for say highway use, where acceleration isn't as much the concern (or even weight), but reduced wear and engine cooling at those sustained speeds is, but displacement vs displacement, pound for pound - you'll sacrifice some power for that *shrug* It's all a trade off :)

Again though - I'm not trying to infer that either is inferior, simply that there's tools that are more appropriate for specific applications.
 
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scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
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Ridin' inSane Diego, CA.
There have been many threads on this subject... :rolleyes:

I totally disagree with the above statement! (except for the fact that they cost more!)
2-stokes don't foul the plugs (if you mix your gas right), they last just as long (if you take proper care of them), they are just as quiet (they both have the exact same mufflers!!), there's zero smoke if you use synthetic oil mixed @ 100:1, they cost less, look better & fit in to more frames, they have far less parts to break, they are much faster!! (there's never been a 4-smoker that could keep up with us on our rides!!), more high performance parts for them & they get 90MPG even after totally hot rodding them!!!

4-strokes are heavier, co$t three times more, they are slower & have way less hill climbing power, they have ten times more parts that can break, require super wide pedal cranks to clear the engine, they have centrifugal clutches (that blow), they're ugly, (they look like you put a lawn mower engine on your bike), they only have pull starts (which break), & no one makes high performance parts for them!



2-strokes rule!!! ;)
I'm just really wondering here how you can actually think that 2-stokes rule??? Other than a 2-stroke winning the Deathrace this year, I can think of none. The AMA Supercross and the AMA motocross series....tell me how they ruled there? Honda, Suzuki, Yamaha, Kawasaki, KTM and Husqvarna, what type of engines are they building and RACING and winning with now? 4-strokes dominated, no dispute!

It's all coming down to 4-strokes and a lot of it is because of the State you live in and our CARB compliency here and the only thing I can think of that makes you think 2-strokes rule is that you're sittin on a couple of containers of em.

Don't get me wrong, I love two-strokes and always have, you just have too make way and let it go as the four-strokes are surpassing and pushing two-strokes out of the future. Just wait...

The AMA Supercross being 99.9% 4-strokes should be an indication of what type of engine really rules!
 

GearNut

Active Member
Aug 19, 2009
5,104
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San Diego, Kaliforgnia
In the AMA motocross races, why were the 250 4-strokes pitted against the 125 2-strokes. Why not pit them against 250 2-strokes?

Yamaha YZ460F against Honda CR250R?
Something seems slanted here....
 

BarelyAWake

New Member
Jul 21, 2009
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I suspect that the current dominance of the four strokes in the AMA racing circuit would be political - after all, the primary reasons for racing is product development and marketing.

What point would there be for the major manufacturers in continuing development on a engine that's become the scapegoat? Pound for pound the two stroke has always had better characteristics for motocross in particular - but if you have the resources of a major manufacturer these differences aren't so much the primary concern as pushing product.

Four strokes will no doubt eventually be the only type available - yet this has nothing to do with it's performance and everything to do with politics. Don't think for a second that politics doesn't effect the racing circuit or engine development lol


BUT - that's all beside the point anyway, we're talking about available engines suitable for mounting on our bicycles. Of those engines available - if we're talking sheer performance per displacement & weight I'm afraid the 2smokers still haven't got any real competition. The only reason any of the available four strokes even come close is because the China two strokes are about as primitive as you can get - throw a Morini into the equation and the debate is over.

That still doesn't mean I think the four stroke inferior in any way - again, for what's available for our bikes, the four stroke is quieter, smoother running and does have better long term reliability & fuel efficiency potential.

It's still about what tool is more appropriate for what you want out of yer ride.
 

BarelyAWake

New Member
Jul 21, 2009
7,194
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Maine
In the AMA motocross races, why were the 250 4-strokes pitted against the 125 2-strokes. Why not pit them against 250 2-strokes?

Yamaha YZ460F against Honda CR250R?
Something seems slanted here....
Really? Is that true? ROFL, if it is - that confirms my political suspicions w/o a doubt...


...and it's kinda lame.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
In the AMA motocross races, why were the 250 4-strokes pitted against the 125 2-strokes. Why not pit them against 250 2-strokes?

Yamaha YZ460F against Honda CR250R?
Something seems slanted here....
Why you ask? The simple answer is a 2-stroke puts out nearly twice the power per displacement of a 4-stroke of equal size. And that is why the AMA allows this ruling. I wasn't talking about raw brake horsepower....my 66cc 2-stroke can spank my piddly little 49cc 4-stroke. Which bike do I prefer to ride everyday...take a guess? Sorry, it's the 4-banger, mini-thumper!

And how many 2-strokes are running against those 4-strokes in the AMA (pick any series, on or off-road ) ? Almost none! Why....you tell me? And what happened to the 500cc open class and all the 500cc 2-strokes that used to race in them???
Where's the 350cc Banshee, the Penton 125cc, the Hodaka 100cc. the 405cc Husky, the 360cc CZ and the 501cc Maico? There are still some very nice 2-strokes out there, like Polini, Morini, Tanaka, Zenoah, Stihl and Chung Yang, but they are getting far and few between....are they not? Who rules, 2 or 4-stroke?

Which type rules is really neither, they both have there place.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
I suspect that the current dominance of the four strokes in the AMA racing circuit would be political - after all, the primary reasons for racing is product development and marketing.

What point would there be for the major manufacturers in continuing development on a engine that's become the scapegoat? Pound for pound the two stroke has always had better characteristics for motocross in particular - but if you have the resources of a major manufacturer these differences aren't so much the primary concern as pushing product.

Four strokes will no doubt eventually be the only type available - yet this has nothing to do with it's performance and everything to do with politics. Don't think for a second that politics doesn't effect the racing circuit or engine development lol


BUT - that's all beside the point anyway, we're talking about available engines suitable for mounting on our bicycles. Of those engines available - if we're talking sheer performance per displacement & weight I'm afraid the 2smokers still haven't got any real competition. The only reason any of the available four strokes even come close is because the China two strokes are about as primitive as you can get - throw a Morini into the equation and the debate is over.

That still doesn't mean I think the four stroke inferior in any way - again, for what's available for our bikes, the four stroke is quieter, smoother running and does have better long term reliability & fuel efficiency potential.

It's still about what tool is more appropriate for what you want out of yer ride.
This is all so true.....might make a sticky out of this....very well put!
 

flybytaco

Metal Molding Madman
Oct 17, 2009
1,170
8
0
seekonk MASS
I have built both so heres my thought...

Skyhawk 66c gt5 vs HS 49cc

The 4-strokes are better, hands down...

The 2-stroke are cheap, unreliable, and a crapshoot at best. Parts are widely available, but for good reason, because things break often. Carbs are almost always out of adjustment, which can lead to premature wear.

The HS is a good little motor. A Japanese design Chinese copy, is better than a Chinese design in my book. Some guy have over 50k on their Huasheng. Show me a 2-stroke with 50k then we can talk. They have a good power band, loads of grunt for a 49cc, plus 7000 rpms equals good top end. The only disadvantage is the gearboxes. Their 6+ to choose from, some better than others. But the EZM shows a proven 45mph+ and silent operation. Show me a 2-stroke single speed that can do that.

Step your game up, get a thumper
my 2 stroke keeps up with a 4 stroke no problem but i would rather have the 4 for the road and my 2 for the dirt
 

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
2,784
26
36
Indianapolis
I havent seen any posts about 4 strokes turning into a grenade within the first 200 miles. Havent seen any posts about trying to get the 4 strokes running after building the kit bike. The two strokes are initially cheaper but after replacing the engine three or for times?
??? Grenade? I think there may be conditions, under which that could happen, which may very well be related to either a less-than-reputable maker's quality or an owner's diligence with upkeep. I know the four-strokes on the lawn mowers and garden tractors I've owned and used and maintained (rather well I may add) were by no means trouble free. If anything, they were right on par with my two-stroke. I know this may be apples-and-oranges but my experience has been that my two-stroke is easier to start. My old arm gets tired after pulling rope a few times. And I think I've rebuilt the carburettor on more four-strokes than I have on two-strokes (well, I haven't had to yet on a two-stroke).
I would say that people who are used to four-strokes will go with what they know, and are more prepared to deal with what they are used to. The exact same can be said for lovers of two-smokers.
 

Dan

Staff
May 25, 2008
12,765
115
48
59
Moosylvania
LOL Scotto. I couldn't agree more. I forget who said it but "We need a 2.5 stroke" I love the smooth, power, speed and easy of my 4 smokers. I love the slim light an' dang sexy looks of my 2 strokes. This must be confusing to new folks but the real deal is they both have +'s and minuses. They both turn the rear wheel and do their job. This comes up over and over but the bottom line is what will you or do you enjoy the most. For me, it is the MB I am on. The 4 banger is more cost efficient in the long run. Sound is more pleasant to most folks and climbs better and goes faster then a China girl. A china girl engine can be swapped out for half or a third the cost and is simple to fix. Throw a high end 2 stroke in and every thing changes. Has all been said over and over and not saying I don't enjoy this conversation. Saying if one finds some thing they are happy with, God bless. Talking about MBs here. Nothing terribly important. (please note I often get off mine, shut her down and say "I love you" But I got the coolest MB on Mother Earth. Nanananna)