why are 4 strokes more reliable

[the doug1789]

i mean worknig on the banshee is about as mindless as it gets so what makes 4strokes that much better?(mechanicly)

[wesw]

4 banger dont fire every time it reachs t.d.c.

 

doesnt have ports that rings could snag on.

[Coupelx]

They usually arent spun as high, making more power down low saving on wear and tear. a 2 stroke is making roughly twice (roughly, ok?) the power at a given displacement than a similarly sized 4stroke, putting more stress on parts.

[FireHead]

i mean worknig on the banshee is about as mindless as it gets so what makes 4strokes that much better?(mechanicly)

It's not that 4 stroke are better, they are just different. A 4 cycle engine gnerally has more even and reliable lubrication due to having an actual regulated oil system. Additionally, cooling (especially across the piston) is generally more even and better controlled. The ring thing on two strokes as mentioned previously can be a factor on certain engines, but on rotary valve or crank induction engine (that differ from reed induction Banshee engines) the ring issue is not a concern.

 

Depending on how indepth you want to get, I am sure several of can make quite a thread out of this topic. :geek:

[FireHead]

They usually arent spun as high, making more power down low saving on wear and tear. a 2 stroke is making roughly twice (roughly, ok?) the power at a given displacement than a similarly sized 4stroke, putting more stress on parts.

A couple of generalizations are made here that could be misleading:

 

For instance, the Moto GP and F1 folks might disagree with you about the rpm thing. Also, the hp/displacement relationship is a classic misconception that used to be relatively true in previous decades, but now is not true when you are speaking of modern engines.

 

I'm not saying any of this to be an ass, but this is quite a wide topic for discussion and speaking to specifics could be misleading, atleast itinitially. :thumbsup:

[Indubitably]

Four strokes aren't necessarily more reliable, it's all about how you take care of it and how you ride it. My banshee went 15 years before it needed a set of pistons. The only reason the ones that I had in there went is because I did something stupid to cause it.

[Coupelx]

A couple of generalizations are made here that could be misleading:

 

For instance, the Moto GP and F1 folks might disagree with you about the rpm thing. Also, the hp/displacement relationship is a classic misconception that used to be relatively true in previous decades, but now is not true when you are speaking of modern engines.

 

I'm not saying any of this to be an ass, but this is quite a wide topic for discussion and speaking to specifics could be misleading, atleast itinitially. :thumbsup:

i was thinking more atv oriented, not car :thumbsup:

[shanYE west]

i was thinking more atv oriented, not car :thumbsup:

 

Today 4 stroke atv engines have no problem spining high RPM's. My 450's rev limiter is 12,500. I dont think I've seen a ATV/Dirt bike single cylinder 2 stroke engine of that size carry that kind of RPM.

 

I'm not 100% sure but I think a yz250F is making about the same power as a trx 250r (Stock/piped)

 

I agree with firehead.. Reliabilty/longevity of the motors comes from the extra lubrication/cooling from the oil system. But.. you do have extra maintainence with the 4 strokes. Valve train's

Edited August 22, 2007 by Fouledout420

[doorslammer]

Four strokes aren't necessarily more reliable, it's all about how you take care of it and how you ride it. My banshee went 15 years before it needed a set of pistons. The only reason the ones that I had in there went is because I did something stupid to cause it.

 

yep, found out a couple of days ago my shee hadnt had a rebuild since 2001 when it was born...lol

 

but it looked good and had reasonable compression

Edited August 22, 2007 by doorslammer

[sled]

Today 4 stroke atv engines have no problem spining high RPM's. My 450's rev limiter is 12,500. I dont think I've seen a ATV/Dirt bike single cylinder 2 stroke engine of that size carry that kind of RPM.

 

I'm not 100% sure but I think a yz250F is making about the same power as a trx 250r (Stock/piped)

 

I agree with firehead.. Reliabilty/longevity of the motors comes from the extra lubrication/cooling from the oil system. But.. you do have extra maintainence with the 4 strokes. Valve train's

yz250f's are like 32-35hp. i have a 04 crf450 thats never had a top done. ive ajusted the valves once, thats it. if i had to guess it probably has somewhere between 2500-3000hours on it. yeah thats no bullshit. ive never been able to do that with any of my 2 stroke. its all on how you ride it if you ask me.

[ojcool]

They aren't. They just are not as hard to start.

 

Seriously, weed wackers, chain saws, anytime you find a guy who can't get it started, you hear "piece of shit". 9-10 two stroke engines don't get taken care of, they get thrown into the back of the barn untill next year, then you waltz out there and grab it, with last years gas, and expect it to start right up... Well I have a chain saw that starts 2nd pull every year, and I DO NOT take care of it AT all. It's tuned right, 2 strokes are alot harder to get tuned right thats all. Old outboard boat engines are considered much more reliable than inboard gas engines. I can tell you thats true from personal experience.

 

With a 4 stroke the clean compression stroke allows it to start on crappier a/f charge than a two stroke.

[locogato11283]

i dont see how 4 strokes are any more reliable. especially in the atv world. there are MANY more moving parts on the newer 4 strokes. that means there is a greater chance something will break. banshee motors are about as simple as you can get. if you put it together right, its unlikely youll have a problem for a long ass time.

[dajogejr]

if i had to guess it probably has somewhere between 2500-3000hours on it. yeah thats no bullshit.

 

I call BS. 2500 to 3000 Hours? C'mon....splitting the difference at 2750 hours, that means since it was new, 3 years old, it's been ridden 10.4% of the time. That's 10% of the total hours available on a 24 hour day, 7 day week, 52 weeks a year. That means you ride your bike every day for 2.2 to 2.3 hours a day roughly. 7 days a week??

 

Ricky Carmichael has (had before he semi-retired) the toughest training regiment in the sport. He only put about 2 hours day on the bike....during the week, and the hour or so on the weekend when he had an event/practice, etc.

 

Here's the math...not taking into account Leap Year.

 

26208 hours in 3 years. (24 a day X 7 X 52 weeks a year X 3 years)

2750 is 10.49% of 26208

 

10.49% of 24 hours (in a day) is 2.51 hours a day...EVERY DAY.

 

I want your job...

 

Last I checked....125cc two strokes rev pretty high, I think in the 12k ball park.

[sled]

I call BS. 2500 to 3000 Hours? C'mon....splitting the difference at 2750 hours, that means since it was new, 3 years old, it's been ridden 10.4% of the time. That's 10% of the total hours available on a 24 hour day, 7 day week, 52 weeks a year. That means you ride your bike every day for 2.2 to 2.3 hours a day roughly. 7 days a week??

 

Ricky Carmichael has (had before he semi-retired) the toughest training regiment in the sport. He only put about 2 hours day on the bike....during the week, and the hour or so on the weekend when he had an event/practice, etc.

 

Here's the math...not taking into account Leap Year.

 

26208 hours in 3 years. (24 a day X 7 X 52 weeks a year X 3 years)

2750 is 10.49% of 26208

 

10.49% of 24 hours (in a day) is 2.51 hours a day...EVERY DAY.

 

I want your job...

 

Last I checked....125cc two strokes rev pretty high, I think in the 12k ball park.

either me or one of my friends rides it everyday. i can promise you that. on saturdays and sundays it gets ridden alot more. it gets 12 hours or more a weekend. Me and a couple a friends were talking about this lastnight which is kinda weird. if i dont ride it when i come home from work, my buddy Walt does. he ajusted the valves once on it since ive had it. i was saying its gotta have between 1600 and 2000 hours, but all my buddies called bullshit on that. when its sitting on Walts Farm he rides when ever hes bored and it gets ridden from 3:30 til dark. the guys at the local dealer called it a freak. i just think it because i take good care of it and no one is riding it around banging it on the rev limiter.

 

Ricky Carmichael rides alot more than 2 hours a day. hes the best in the world! a bunch my buddies ride more than that everyday and only 1 was able to go Pro. he cant even compare to Ricky.

Edited August 23, 2007 by sled

[NYUK]

a properly maintained 2 stroke will last just as long if not longer between rebuilds as a thumper.jetted correctly. i have seen 65 hp banshee motors last 5 years without a rebuild. with very little compression loss.it is all about the level of preventative maint done.jetting, checking boots and such for airleaks, checking for loose bolts.thats a myth.