Welcome back to us :/ Our hosts data center was down for the entire day.
MotoHouston.com MotoHouston.com
Register Members List Member Map Media Calendar Garage Forum Home Mark Forums Read

Go Back   MotoHouston.com > General Discussion > General Discussion (Moto Related)
Forgot info?

Welcome to MotoHouston.com! You are currently viewing our forums as a guest which gives you limited access to the community. By joining our free community you will have access to great discounts from our sponsors, the ability to post topics, communicate privately with other members, respond to polls, upload content, free email, classifieds, and access many other special features. Registration is fast, simple and absolutely free, join our community!

Register Today!

If you have any problems with the registration process or your account login, please contact us.


FREE MH Decals by MAIL!

Advertisement

Reply
Share This Thread: 
Subscribe to this Thread Thread Tools
Old 07-18-2007, 12:02 PM   #1
[poser]
"the un-original"
 
[poser]'s Avatar
 
Join Date: Jul 2007
Location: Katy
Feedback Rating: (0)
Posts: 628

Experience: 10+ years
Trackdays: 4

Bike(s):
'o7 sv650s: Tundra DC 5.7: Trek 1.2
wish I had a motard / dual sport, it'll be next








2 stroke vs. 4 stroke

I haven't found a thread here comparing the two, so I'm starting one. My recent interest into the world of mini-moto, has me at a fork in the road.
One way goes towards 2 strokes, and the other towards 4 strokes.
Which is better and why?
__________________
Jason
'07 sv650s and '08 Tundra 5.7
Quote:
Originally Posted by my father-in-law
Jason is hard to read, I can't always tell if he's joking or if his jugdment really is that bad
[poser] is offline   Reply With Quote
Similar Topics
Thread Thread Starter Forum Replies Last Post
4-stroke to 2-stroke Conversion Stang Man General Discussion (Moto Related) 8 05-07-2011 09:34 AM
2-stroke vs. 4-stroke Scorch Dirtbikes, Mini's, ATV's..... 19 07-13-2010 09:45 AM
2 stroke help bentgixxer Dirtbikes, Mini's, ATV's..... 24 03-04-2009 08:46 AM
2 stroke pester Dirtbikes, Mini's, ATV's..... 8 10-28-2008 05:05 PM
2 stroke help please stlal How To's and Q & A's 26 01-10-2007 04:23 PM
Advertisement
Old 07-18-2007, 12:20 PM   #2
level5
moving chicane
 
Join Date: Aug 2006
Feedback Rating: (0)
Posts: 5,825












Four stroke for reliability. No need to mix gas/oil. So far that is all I could think of.
level5 is offline   Reply With Quote
Old 07-18-2007, 12:21 PM   #3
GABRIEL
Senior Member
 
GABRIEL's Avatar
 
Join Date: Jan 2007
Location: SW/SE Houston
Feedback Rating: (14)
Posts: 7,184

Experience: 1-3 months











Where you at Hotnanas?
The 2 strokes are prob going to be faster on the track with more maintnece and the CRF, KLX, DRZ, TTR are all going to run with little maint.
GABRIEL is offline   Reply With Quote
Old 07-18-2007, 12:22 PM   #4
alrova
- LSTD - From 0 to Snail
 
alrova's Avatar
 
Join Date: Jul 2006
Location: NW-Houston
Feedback Rating: (1)
Posts: 3,861

Experience: 1-3 months
Trackdays: 1

Bike(s):
09 ZX-6R









Send a message via MSN to alrova Send a message via Yahoo to alrova
TWO STROKE ENGINES - THE DISPUTED LIST
Advantages:
- Two-stroke engines do not have valves, simplifying their construction.
- Two-stroke engines fire once every revolution (four-stroke engines fire once every other revolution). This gives two-stroke engines a significant power boost.
- Two-stroke engines are lighter, and cost less to manufacture.
- Two-stroke engines have the potential for about twice the power in the same size because there are twice as many power strokes per revolution.

Disadvantages:
- Two-stroke engines don't live as long as four-stroke engines. The lack of a dedicated lubrication system means that the parts of a two-stroke engine wear-out faster. Two-stroke engines require a mix of oil in with the gas to lubricate the crankshaft, connecting rod and cylinder walls.
- Two-stroke oil can be expensive. Mixing ratio is about 4 ounces per gallon of gas: burning about a gallon of oil every 1,000 miles.
- Two-stroke engines do not use fuel efficiently, yielding fewer miles per gallon.
- Two-stroke engines produce more pollution.
From:
-- The combustion of the oil in the gas. The oil makes all two-stroke engines smoky to some extent, and a badly worn two-stroke engine can emit more oily smoke.
-- Each time a new mix of air/fuel is loaded into the combustion chamber, part of it leaks out through the exhaust port.
__________________
--Alberto--
New weapon - "Green Hornet Kato Style powered by Stoner's blood drop stolen by Melandri injected by Lascorz"
alrova is offline   Reply With Quote
Old 07-18-2007, 12:23 PM   #5
GABRIEL
Senior Member
 
GABRIEL's Avatar
 
Join Date: Jan 2007
Location: SW/SE Houston
Feedback Rating: (14)
Posts: 7,184

Experience: 1-3 months











If you are doing it just for fun I would go with a 100 or bigger 4stroke for the win.
GABRIEL is offline   Reply With Quote
Old 07-18-2007, 12:23 PM   #6
alrova
- LSTD - From 0 to Snail
 
alrova's Avatar
 
Join Date: Jul 2006
Location: NW-Houston
Feedback Rating: (1)
Posts: 3,861

Experience: 1-3 months
Trackdays: 1

Bike(s):
09 ZX-6R









Send a message via MSN to alrova Send a message via Yahoo to alrova
The cool page with moving graphics on Howstuffworks.com and this even better one at carbibles.com.

A 4 stroke engine usually has a distributor that supplies a spark to the cylinder only when its piston is near TDC on the compression stroke, ie. one spark every two turns of the crank shaft. Some 4 stroke engines do away with the distributor and make sparks every turn of the crank. This means a spark happens in a cylinder that just has burnt gasses in it. This just means the sparkplug wears out faster.

This from Michael from BIGENZ:
Most of what is written below on advantages and disadvantages of 2 strokes Vs 4 strokes is not actually correct! Take for example the lubrication issue of 2 stroke engines, sure small chainsaw engines may have the oil mixed with the fuel but this is not a direct result of the engine being a 2 stroke, this is just a result of someone designing a very simple engine. look at any large Caterpillar, or Detroit 2 stroke they have conventional oil sumps, oil pumps and full pressure fed lubrication systems and they are 2 stroke!!! also the argument about valves of 4 strokes Vs reeds and ports of 2 strokes is also incorrect. Sure some simple 2 strokes may use very primative systems to achieve the conrol of fuel/air mixture into the engine and exhaust out of the engine but again this is not a function of them being 2 stroke! I've worked on 2 stroke engines that feature poppet valves in the head (like a standard 4 stroke) - but they are definately 2 stroke - it's just that engines like this are not so much in the public eye - next time an ocean liner (ship) pulls into port check out its 2 stroke, turbo charged, direct injected diesel engine!! Finally the arguments of simplicity, weight, power to weight, and cost of manufacturing are not a funtion as such of 2 stroke Vs 4 stroke engines. The mistake of most of these commentaries is that they are comparing a simple chainsaw 2 stroke engine Vs a complex 4 stroke engine from a automobile - not a very fair comparision. As far as emmisions of 2 strokes - check out the Surrich/Orbital 2 stroke design that Mercury outboards are using - this is as clean burning as any 4 stroke.

The ONLY correct comparison below of 2 strokes Vs 4 strokes is that a 2 stroke can (in theory) produce twice the power of a 4 stroke for the same sized engine and the same revs.

As for the diagram [in the Snowmobiles episode of Scrapheap Challenge] - sure small 4 stroke engines do tend to "waste fire" the spark plug at the end of the exhaust stroke but this would not cause an explosion as depicted in the diagrams, but again here the idea of "waste firing"has noting to do with the 4 stroke cycle, rather it is a result of the simple design of a lawnmower motor. The diagrams should depict the inherant differances of a 2 stroke and 4 stroke engine. Hence one should show a firing every revolution and the other a firing every 2 revolutions.

TWO STROKE ENGINES - THE DISPUTED LIST
Advantages:
- Two-stroke engines do not have valves, simplifying their construction.
- Two-stroke engines fire once every revolution (four-stroke engines fire once every other revolution). This gives two-stroke engines a significant power boost.
- Two-stroke engines are lighter, and cost less to manufacture.
- Two-stroke engines have the potential for about twice the power in the same size because there are twice as many power strokes per revolution.

Disadvantages:
- Two-stroke engines don't live as long as four-stroke engines. The lack of a dedicated lubrication system means that the parts of a two-stroke engine wear-out faster. Two-stroke engines require a mix of oil in with the gas to lubricate the crankshaft, connecting rod and cylinder walls.
- Two-stroke oil can be expensive. Mixing ratio is about 4 ounces per gallon of gas: burning about a gallon of oil every 1,000 miles.
- Two-stroke engines do not use fuel efficiently, yielding fewer miles per gallon.
- Two-stroke engines produce more pollution.
From:
-- The combustion of the oil in the gas. The oil makes all two-stroke engines smoky to some extent, and a badly worn two-stroke engine can emit more oily smoke.
-- Each time a new mix of air/fuel is loaded into the combustion chamber, part of it leaks out through the exhaust port.


And from Jonne's page: Why 4-stroke beats 2-stroke

First some explanation on how the 4-stroke engine works:
When the piston moves down fresh air and gas is sucked inside the cilinder from the carburettor. When the piston moves up again the valves are closed and the air is being compressed. When the piston reaches it's highest position the sparkplug produces a spark that ignites the fumes and causes an explosion. Because of the power of the explosion the piston is pushed back. When the piston moves back up again the exhaustvalve is open and the fumes are pushed out the cilinder. Now the whole process restarts (exactly after 4 strokes. That's why we call it a 4-stroke engine...Duh!).

The 2-stroke engine works a little different. It performs 2 strokes at the same time (twice) so after only 2 strokes the whole process restarts. A two stroke engine uses the space above and below the piston. Below the piston are fresh gasses, above the piston these gasses are ignited. Assume the piston is in the lowest position with fresh gasses in the cilinder above it. When the piston moves up, these gasses are compressed, but at the same time teh airpressure below the piston drops and fresh air is sucked inside. When the piston is in it's highest position the sparkplug ignites the gasses and the piston is pushed down. About halfway down a channel from the fresh gasses to the exhaust gasses opens and a channel to the exhaust. Because of airpressure differences the fresh gasses flow inside the cilinder pushing the exhaust fumes out. Now the process starts again. As you can see this only took 2 strokes.

But which one is better?!? Of coarse "we" 4-stroke people say 4-stroke, but do you know why?? Probably not, so I'll explain. First I'll name some of the advantages of the 2-stroke engine over the 4-stroke engine.


When the engine is reving at 10000rpm the 2-stroke engine ignites gasses 10000 times per minute while 4-stroke engines ignite only half. So it should have twice as much power, right?
The 2-stroke engine does have channels for air transport but the piston opens and closes the channels, in a 4-stroke engine there are seperate valves and a camshaft that do this. This means extra moving parts and a far more difficult cilinderhead design. Because of this maintenance is more difficult.
2-stroke engines give more power. At 50cc races 2-stroke bikes can reach speeds of over 130km/h while 4-stroke bikes can hardly reach those speeds with 70cc!! The same applies to everyday use. When you remove some restrictors from a scooter it will go 80km/h. You won't reach these speeds with you're 4-stroke bike by just removing some restrictors.
What about the advantages of 4-stroke bikes? Are there any? OF COURSE! LOTS!!


So what does a stock 2-stroke bike use? About 1 liter fuel per 35km. What does a stock 4-stroke bike use? About 1 liter fuel per 50km!
2-stroke bikes burn oil!! This absolutely doesn't give them more power and is of no use at all (for ignition pusposes), all it does is clogg up the exhaust and smell bad! So why they do it? They have to lubricate the cilinder and cilinderchannels big time or the engine will be wrecked...
Look at the cilinder(head) of both engines. Notice the HUGH cooling fins on the 2-stroke engine. Heck, some of them even have forced air cooling or even water cooling.Did you burn the fuel for heat!?! I don't think so! 2-stroke bikes waste much more energy on heat than a 4-stroke bike does so the 4-stroke engine is much more energy efficient.
Did you read the part on how the 2-stroke engine works?? Did you notice fresh fumes are used to push out the exhaust fumes?? Of course these two gasses will mix in that process, so or fresh fumes are pushed out too or exhaust fumes stay in, either way, it's bad and it sucks.
Ever tried to speed up a 2-stroke bike?? So fast that it could do speeds of over 100km/h. If you have you know you have to add lots of extra oil to the fuel and even than it's a big problem to keep the engine running for let's say a couple of months without mayor engine damage, wasted cilinders and screwed up pistons. Take a 4-stroke engine on the other hand and it will keep running fine for months and months and months... without extra oil The reason is that because of those channels in the cilinder it's much harder to keep it lubricated enough all the time. The 4-stroke engine doesn't have this problem because it has no channel in the cilinder.
Have you ever drove on a Honda MT/MB or anything comparable with a fast cilinder? Did you notice it only had power between about 9000 to 12000 rpm?? Take a 4-stroke engine and it will have power from 1000 to 12000rpm. No problem! The reason is that such a 2-stroke cilinder has optimized airflow channels for that rpm range, outside that range the whole gas mixture gets screwed up big time. That's why those scooter engines always run at almost the same rpm. To optimize airflow, without that a 2-stroke engine looses a lot of it's power.
Because of technical aspects the 2-stroke engine can only have it's intake channel open only half as long as the 4-stroke engine...What a pitty
Listen to the sound of both engines...Doesn't need further explanation I suppose.

Yeah, yeah, I know, 2-stroke bikes with the same displacement are faster, but look at it in another way. A 50cc racing 2-stroke engine will use over a liter per 10km. Now take a 4-stroke engine that uses the same amount of fuel. I guess you would end up with a 90cc or even a 106cc with a 26mm carb or something. No try beating such a machine with that crappy 50cc racebike thing
__________________
--Alberto--
New weapon - "Green Hornet Kato Style powered by Stoner's blood drop stolen by Melandri injected by Lascorz"
alrova is offline   Reply With Quote
Old 07-18-2007, 12:24 PM   #7
Faylaricia
The Comtesse
 
Faylaricia's Avatar
 
Join Date: Aug 2006
Location: NW Houston
Feedback Rating: (0)
Posts: 2,965

Experience: 4 years
Trackdays: 3

Bike(s):
'02 Honda VFR800









I you want to run with TMGP, stick with the 4-strokes.
__________________
Patricia
banner2 sm
Faylaricia is offline   Reply With Quote
Old 07-19-2007, 01:34 PM   #8
mcd
Senior Member
 
Join Date: Apr 2006
Location: Cypress
Feedback Rating: (0)
Posts: 884












But if you want to go fast on a mini, get a two stroke! Unless you have the dough for a 150R.
mcd is offline   Reply With Quote
Old 07-19-2007, 01:43 PM   #9
Faylaricia
The Comtesse
 
Faylaricia's Avatar
 
Join Date: Aug 2006
Location: NW Houston
Feedback Rating: (0)
Posts: 2,965

Experience: 4 years
Trackdays: 3

Bike(s):
'02 Honda VFR800









Quote:
Originally Posted by mcd
But if you want to go fast on a mini, get a two stroke! Unless you have the dough for a 150R.
TMGP allows up to 80cc 2-stroke.
__________________
Patricia
banner2 sm
Faylaricia is offline   Reply With Quote
Old 07-19-2007, 01:45 PM   #10
ArturoC
51% Geek, 49% SuperHero
 
ArturoC's Avatar
 
Join Date: Nov 2005
Location: Atascocita
Feedback Rating: (0)
Posts: 23,248


Bike(s):
'99 GSXR600
'04 NSR 50
'09 Yamaha WR250X
'07 Triumph 675

Member Garage





Send a message via ICQ to ArturoC Send a message via AIM to ArturoC Send a message via Yahoo to ArturoC Send a message via Skype™ to ArturoC
I like-a da 2, but I wanna da 4
__________________
Blog | Pics | YouTube
CMRA [Prov Nov]ice #404
Sponsors: D&D - GoPro - Amsoil
ArturoC is offline   Reply With Quote
Old 07-19-2007, 01:58 PM   #11
[poser]
"the un-original"
 
[poser]'s Avatar
 
Join Date: Jul 2007
Location: Katy
Feedback Rating: (0)
Posts: 628

Experience: 10+ years
Trackdays: 4

Bike(s):
'o7 sv650s: Tundra DC 5.7: Trek 1.2
wish I had a motard / dual sport, it'll be next








according to their website you can run 85cc 2 stroke, which opens up the honda cr85
for me that doesn't mean I'll be better or more competitive, it just means I have more choices of bikes when the time comes
__________________
Jason
'07 sv650s and '08 Tundra 5.7
Quote:
Originally Posted by my father-in-law
Jason is hard to read, I can't always tell if he's joking or if his jugdment really is that bad
[poser] is offline   Reply With Quote
Old 07-19-2007, 02:02 PM   #12
Blue91
10.13.07
 
Blue91's Avatar
 
Join Date: Feb 2007
Location: NW Houston
Feedback Rating: (3)
Posts: 2,217

Experience: 7 years

Bike(s):
2010 White R6
2003 Silver R6 (sold)



Member Garage





Send a message via Yahoo to Blue91
80cc 2? Hmmm, might have to bring my YZ80 out some day. That fugger is FAST for a stock bike (to me at least, haha).
__________________
gixxerbill - MotoHouston.com's Lifetime Intolerance Award Winner

Blue91 is offline   Reply With Quote
Old 07-19-2007, 02:33 PM   #13
hotnanas
i rock knobbies
 
hotnanas's Avatar
 
Join Date: Sep 2005
Feedback Rating: (4)
Posts: 8,881

Experience: 10+ years











2stroke - You have to mix the oil and the gas. How is this a disadvantage? It's so easy. I fill the jug with 4.2 gallons of gas. I dump in half a liter of premix. I'm good to go. Where's the struggle? 32:1 all day. I can do it when I'm asleep.

maintenence isn't that bad either. replacing top ends are cheap and easy by comparison to the 4T. Plus you never have to worry about valves.

personally, i i think i love the two strokes because i love the smell of the oil burning. I can't wait to pick up a 4stroke dirtbike though for that wide range powerband.

2T are apparent big time polluters as well. Sorry kids, Daddy had fun killing the ozone layer

Last edited by hotnanas; 07-19-2007 at 02:38 PM.
hotnanas is offline   Reply With Quote
Old 07-19-2007, 02:37 PM   #14
Longnguyen
Senior Member
 
Longnguyen's Avatar
 
Join Date: Aug 2006
Feedback Rating: (0)
Posts: 982












i will voice my opinion here.........as tech. improves, the 4-stroke being more advanced....it is gaining grounds/passing the 2 strokes in terms of performance/reliability. the 4 stroke will be better.......why? because the 2 cycle is abandoned by the industry so sooner or later you will have problems finding support for the engine. Performance differences are mainly in terms of power delivery now...........the 2- has abrupt power while the 4 is more linear both will achieve same peak for a given engine. reliability is the same for both, take care of it and it will last.
Longnguyen is offline   Reply With Quote
Old 07-19-2007, 03:05 PM   #15
jus10
Loading...
 
jus10's Avatar
 
Join Date: Nov 2006
Feedback Rating: (0)
Posts: 2,160

Experience: 10+ years

Bike(s):
KX TooNifty









I personally would pick the lighter/smaller 2 stroker instead the bigger heavier 4 stroke. The power comes on differently, but the main difference is the low-end torque. As stated in the novel up top, the 2 strokes can put out twice as much power as the 4 stroke of the same displacement. So the only way to get that power from a 4 stroke is to get the bigger bike.

side note: I am still waiting on a 4 stroker to beat my 80. (not saying it's impossible, just haven't seen it yet.) I really want a piece of a nice 150.
For reference, my 80 is faster than a kx100.
jus10 is offline   Reply With Quote
Old 07-19-2007, 08:55 PM   #16
GunMedalGleam
Member
 
Join Date: Jun 2007
Feedback Rating: (0)
Posts: 63












2 strokes are alot faster, but make alot of smoke.+you have to keep it a high rpms to make power.
GunMedalGleam is offline   Reply With Quote
Old 07-19-2007, 09:11 PM   #17
ArturoC
51% Geek, 49% SuperHero
 
ArturoC's Avatar
 
Join Date: Nov 2005
Location: Atascocita
Feedback Rating: (0)
Posts: 23,248


Bike(s):
'99 GSXR600
'04 NSR 50
'09 Yamaha WR250X
'07 Triumph 675

Member Garage





Send a message via ICQ to ArturoC Send a message via AIM to ArturoC Send a message via Yahoo to ArturoC Send a message via Skype™ to ArturoC
Quote:
Originally Posted by GunMedalGleam
+you have to keep it a high rpms to make power.

Good point, especially on these small bikes. 2 strokes have a much more narrow powerband compared to the 4 strokes, so to keep the engine revs inside the powerband, you will be shifting a LOT.

For example, riding my NSR50 at the Katy track requires 14 - 16 shifts per lap. Riding a ysr with an xr100 4stroke, only requires 2 - 4 shifts per lap.

I still like my 2 stroke though :icon_bigg
__________________
Blog | Pics | YouTube
CMRA [Prov Nov]ice #404
Sponsors: D&D - GoPro - Amsoil
ArturoC is offline   Reply With Quote
Old 07-19-2007, 09:46 PM   #18
mcd
Senior Member
 
Join Date: Apr 2006
Location: Cypress
Feedback Rating: (0)
Posts: 884












That is the big difference for me, how much do you want to shift. You do have a broader power band with a four stroke. I like the fact with my CR85 though that when you are in the powerband, it is a challenge to keep the front wheel on the ground. Much more excitement from a two smoke than an comparible displacement 4. To each there own though.
mcd is offline   Reply With Quote
Old 07-20-2007, 08:10 AM   #19
[poser]
"the un-original"
 
[poser]'s Avatar
 
Join Date: Jul 2007
Location: Katy
Feedback Rating: (0)
Posts: 628

Experience: 10+ years
Trackdays: 4

Bike(s):
'o7 sv650s: Tundra DC 5.7: Trek 1.2
wish I had a motard / dual sport, it'll be next








could the difference between the two, be compaired to riding a i-4 vs v-twin
__________________
Jason
'07 sv650s and '08 Tundra 5.7
Quote:
Originally Posted by my father-in-law
Jason is hard to read, I can't always tell if he's joking or if his jugdment really is that bad
[poser] is offline   Reply With Quote
Old 07-20-2007, 10:37 AM   #20
jus10
Loading...
 
jus10's Avatar
 
Join Date: Nov 2006
Feedback Rating: (0)
Posts: 2,160

Experience: 10+ years

Bike(s):
KX TooNifty









I wouldn't say so...
jus10 is offline   Reply With Quote
Reply


Thread Tools

Advertisement


All times are GMT -5. The time now is 05:33 PM.


MotoHouston.com is not responsible for the content posted by users.
Privacy Policy