I've ridden both 2 stroke and 4 stroke race quads. I raced 2 strokes in juniors on a 200cc watercooled quad and then moved up to 4 stroke 450 at the start of last year for seniors. I'd say 2 strokes even though they are more demanding are a lot more fun to ride. Too bad they just don't seem to cut the mustard against modern 4 stroke motors.
2 stroke vs 4 stroke... the great debate.
- Thread starter chubbywubby
- Start date
And also whether or not the motor has a power valve
top_dog
Likes Dirt
I've ridden a few different bikes recently. And I don't think its 2 or 4 stroke that is really the critical factor, but how the bike is set up.
Both 2 and 4 strokes can be set up with a broad spread of power or a narrow band. My Gas Gas trials bike could take off from a stop in 6th gear without too much clutch slipping, because its tuned for torque.
As far as more conventional enduro or trail bikes are concerned, I think for a small person a two stroke is much better just because it it far lighter. My WR125 weighs 99kg, a WR250 is up about 118kg AFAIK, that is a big difference when you are staring to get tired after a long ride in the hills. The inertia of those extra cams makes a difference in the tight too I've been told.
Next thing, is a 2 stroke is so much easier to work on. Top end rebuild is no dramas for me, don't know that I'd do a 4 stroke top end in the shed though.
I think that the better power to weight, and the simplicity of a 2 stroke is better.
Both 2 and 4 strokes can be set up with a broad spread of power or a narrow band. My Gas Gas trials bike could take off from a stop in 6th gear without too much clutch slipping, because its tuned for torque.
As far as more conventional enduro or trail bikes are concerned, I think for a small person a two stroke is much better just because it it far lighter. My WR125 weighs 99kg, a WR250 is up about 118kg AFAIK, that is a big difference when you are staring to get tired after a long ride in the hills. The inertia of those extra cams makes a difference in the tight too I've been told.
Next thing, is a 2 stroke is so much easier to work on. Top end rebuild is no dramas for me, don't know that I'd do a 4 stroke top end in the shed though.
I think that the better power to weight, and the simplicity of a 2 stroke is better.
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mlsred
Likes Dirt
I would enter this debate but I might be a little biased as some of you would know, also never ever question wombat about his knowledge on 2 strokes I have wombats dads old race bike and the things he did to make it go faster are just amazing.
2 strokes are so much easier to rebuild/tune and a good one will run forever and a day if built properly.
2 strokes are so much easier to rebuild/tune and a good one will run forever and a day if built properly.
skivi
Likes Dirt
2-stroke VS 4-stroke = Apples VS Oranges.
my OT two-banger rant:
the two-stroke engine does not commonly require big $$ inputs to raise power output in the way 4T's often can. sucessfully modifying 2t engines for widdowmakking power does however require an in-depth under-standing on the part of the man doing the modifications into the way the engine works to obtain any positive results.
when modifying two strokes carburettion, compression ratios, port timings and expansion chamber designs must all must work in harmony with the basic engine design & the myriad of processes and fundamental physical forces acting within the motor if your after any real power gain.
when people talk about the power band of a two-stroke cycle engine this refers to the power making and power delivery characteristics of said motor. each aspect of a 2T engine has a role to perform, the specific way each process does it's job has a profound effect on the other fundamental process of the motor and how it makes it's power.
you can take a 2T Honda CR500 factory racer tyre shredder from a monster to a mouse just by changing the pipe to a straight garden hose. take a ferrari and muffle the hell out of the exhaust till it sounds like a sewing machine and you'll still smoke joe shmoe at the drags.
if anyone is after 2T literature i've got a pile of it on PDF and links too.
my OT two-banger rant:
the two-stroke engine does not commonly require big $$ inputs to raise power output in the way 4T's often can. sucessfully modifying 2t engines for widdowmakking power does however require an in-depth under-standing on the part of the man doing the modifications into the way the engine works to obtain any positive results.
when modifying two strokes carburettion, compression ratios, port timings and expansion chamber designs must all must work in harmony with the basic engine design & the myriad of processes and fundamental physical forces acting within the motor if your after any real power gain.
when people talk about the power band of a two-stroke cycle engine this refers to the power making and power delivery characteristics of said motor. each aspect of a 2T engine has a role to perform, the specific way each process does it's job has a profound effect on the other fundamental process of the motor and how it makes it's power.
you can take a 2T Honda CR500 factory racer tyre shredder from a monster to a mouse just by changing the pipe to a straight garden hose. take a ferrari and muffle the hell out of the exhaust till it sounds like a sewing machine and you'll still smoke joe shmoe at the drags.
if anyone is after 2T literature i've got a pile of it on PDF and links too.
Pete_10
Likes Bikes and Dirt
Yes, and no, I screwed up a little it isn't so much extra but more like bigger.
Yamaha's system is called YPVS (Have a read if you still don't believe me) and it does alter the shape of the exhaust valves. Honda has also used a similar system but the valves were opened by an electric servo.
The reeds have nothing to do with the actual power band itself (power valve, which is another whole part) that is just a part of the way a normal bike runs.
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chubbywubby
Likes Bikes
thanks for all you help guys....
wombat
Lives in a hole
See, that's what I'd always thought, and why I always wondered what I was missing when I heard people saying "Nah bro, don't get a four stroke, it doesn't have powerband".
The concept of the power band on the rev range isn't unique to 2 strokes either, 4 strokes have a powerband, but more often it's of such a nature that it doesn't try to rip your arms off and bang your girlfriend, all at the same time. I understand that all these valve/reed systems will change the way torque and power is distributed across the range, and thus change the characteristics of the power band, it was just the terminology that I was curious about.
james_lambie1
Squid
i have a 150r and they are just as much maintenance as a 85 if not more. they also have just as much power as the 85s but the 150s are just easier to ride.
moto-james
Likes Dirt
Wronghey all,
if i get a four stroke it will be less expensive to run.
Tom.
4 stokes chew through chains and sprockets faster
they also require higher maintenance
....
And someone said 2strokes are lighter...thats also wrong
250 2 stroke vs 250 4 stroke //////4 stroke = lighter
although 250 2 strokes vs 450 4 strokes......meaning the 2 stroke is lighter
floody
Wheel size expert
Are you serious? PLEASE don't post any more moto tech 'advice'.
"Powerband" refers ONLY to the spread of power a bike makes; where in the rev range it delivers strong torque/acceleration.
IT IS NOT A PHYSICAL COMPONENT.
This is kindergarten, get laughed at by your mechanic stuff.
Yes most modern two strokes vary exhaust port shape and thus timing by use of a sliding port segment. This is called a Powervalve. Kawasaki have K.I.P.S., Yamaha have Y.P.V.S., Suzuki have Slingshot...etc all doing the same thing and actuated electronically or centrifugally generally.
Jimass
Eats Squid
Anyone compared a 250f back to back with a 250 two banger?
I've done it with a WR250 (05, Husky) and a yzf250 (04, Yamaha)
Husky owned it everywhere.
In the power, cornering, and just general servicing/maintenance.
But it wasn't really a good comparo, with the Husky being a trail/enduro bike it should of beaten the Yzf with maintenance anyways, cause the Yzf is a race bike, and is expected to have the oil changed basically every ride.
The Yzf also had a Leo Vince (?) pipe.
I've done it with a WR250 (05, Husky) and a yzf250 (04, Yamaha)
Husky owned it everywhere.
In the power, cornering, and just general servicing/maintenance.
But it wasn't really a good comparo, with the Husky being a trail/enduro bike it should of beaten the Yzf with maintenance anyways, cause the Yzf is a race bike, and is expected to have the oil changed basically every ride.
The Yzf also had a Leo Vince (?) pipe.
Pete_10
Likes Bikes and Dirt
Brain fart on the wording, fuck, my bad, was basically just reading and following. Was just about to edit it with an explanation of everyone talking the same shit about two different things (band vs valve)
moto-james
Likes Dirt
Those 2 bikes dont even compete against each other
125 2 strokes compete against 250 f
250 2 strokes compete against 450f
they have no allowed 150 2 strokes to compete with 250f's as well
Ultra Lord
Hurts. Requires Money. And is nerdy.
In the latest ADB i swear it said something along the lines that U19 MX had 250 two strokes are eligible in the lites class, or something along those lines... disregarding technicalities they race together in a class for teens, maybe not in Australia though.
I reckon 150s should be allowed to race 250s, the 125s just don't seem to have the same power as a 250.
Is that the one with 2 stroke Vs. 4 stroke on the front cover?
Graunched
Likes Dirt
WTF are you talking about?
If you go to www.ktm.com and compare the 09 250EXC to the 09 250EXC-F
you will find that the two stroke is 5 kilos lighter.
I would post a link of the comparison but it wont let me, nor will it fit on one screen shot. Please back up your claim with hard evidence, like I have provided as I would be interested to find this magical 4 stroke.
moto-james
Likes Dirt
the 09 250EXC is 100.8kg
the 09 250EXC-F is 1005 kg
|Matt|
Banned
Which is what Graunched said...
2 strokes are typically lighter bikes, I thought that was well established.