Two Stroke Motocross
Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: motoman356 on March 16, 2010, 11:25:11 PM
-
in order to get the 4t's they have to run them at lower decibels ridiculous. if they ever tested near where a pro rides the bikes if would never pass. even with a q pipe
http://www.motocrossactionmag.com/ME2/dirmod.asp?sid=&nm=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&tier=3&nid=68E106238C6E412B8E36C6317D3FF97F (http://www.motocrossactionmag.com/ME2/dirmod.asp?sid=&nm=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&tier=3&nid=68E106238C6E412B8E36C6317D3FF97F)
-
Someplace else I posted that Pro Circuit tested 4 stroke pipes on a dyno. They made 90db, 92db, 93db and more... using the AMA rules each one met the sound level at the low rpm level, but when they did a drive by of the bikes it was over 110 db!! Worse yet full out on the dyno with the same AMA test all of the bikes clocked within 1 db of each other at 130db!!!
The current AMA sound rule is a joke!!
I'm convinced that even if they kept the displacement rule lopsided and just lowered the sound level rule to a reasonable level that the two-strokes could not only compete, but probably beat them!
-
John,
that is exactly the reason I have not been back to a National MX since 06 at Southwick. My ears were still ringing the next day from the exhaust noise. I get to attend AMA Pro events for free and I don't go!
There is no way the sound levels are in the 95DB range with these modern 4S. 130DB seems closer to the mark.
Paul P
-
Paul - hopefully you'll come out to Southwick in 2010 to see a 250cc two-stroke compete against the tractor 450's!!
I agree with you... and I too stopped going to the Pro races because of sound. Funny it was at Southwick that I felt this way as well! Last year at Unadilla was the first time I went back in a couple of years and only because they had the FMF 2 Stroke Invitational.
The only way to shift the tide is to get two-strokes out there in the Pro Classes and get the fans excited about them. My feeling is that this change will be the only way to bring two-strokes back.
-
Hopefully there will be a lot of 2 strokes at the event. But, I will still have to wear earplugs if the 4 bangers are there. And I agree, if the 4S were Actually as quiet as the 2S they would not have the power they now enjoy.
-
Now just imagine the power the two-strokes would have if they were designed to be that loud. I do think that if the engineers set out to make the most powerful two-stroke possible, noise be damned, it'd open, loose, and loud as hell. Of course, matching the 4T sound level is the wrong way to go about anything, but if it were acceptable to go up to 130dB or so, I think we'd have some pretty radical power in our court.
-
Now just imagine the power the two-strokes would have if they were designed to be that loud. I do think that if the engineers set out to make the most powerful two-stroke possible, noise be damned, it'd open, loose, and loud as hell. Of course, matching the 4T sound level is the wrong way to go about anything, but if it were acceptable to go up to 130dB or so, I think we'd have some pretty radical power in our court.
While I'm no engineer, I don't think this is true... as discussed before a properly tuned modern two stroke needs back pressure to produce power... while it might be true that you could get a few additional horsepower if noise were not an issue is possible, I just don't see how.
As for getting more power, if all you want is horsepower... the kart guys are getting 70 to 75 horsepower out of a 250cc engine!! This would not be usable in an mx bike for two reasons, first and most importantly, it would break the rear wheel loose at inopportune times, and basically be unridable. Talk about a light switch!
Second reason is the pipe design parameters on a bike... by it's nature there must be twists and turns i to fit it on the frame and not have it stick out too far on either side. Plus the diameter needs to be larger in order to produce such large horsepower numbers....
Now maybe if you flipped the engine around on a two-stroke...... with the exhaust coming out the back.... hmmm...
(http://3.bp.blogspot.com/_OPLSO0zMObY/St991hTfNuI/AAAAAAAAALI/2NR1KXppNnc/s400/hondamodeld.jpg)
Check out the exhaust coming out the rear of this old Honda.... if this was built in the 1950's how come Yamaha calls it advanced on the 2010 YZF450 tank??
-
Check out the exhaust coming out the rear of this old Honda.... if this was built in the 1950's how come Yamaha calls it advanced on the 2010 YZF450 tank??
Damn it John, I laughed so hard at that I spewed coffee all over my keyboard...... :o ;D
-
Hehe, good point with that Honda. My very first bike was a '79 3.5hp minibike and that Tecumseh engine had the exhaust coming out the back too.
-
Now just imagine the power the two-strokes would have if they were designed to be that loud. I do think that if the engineers set out to make the most powerful two-stroke possible, noise be damned, it'd open, loose, and loud as hell. Of course, matching the 4T sound level is the wrong way to go about anything, but if it were acceptable to go up to 130dB or so, I think we'd have some pretty radical power in our court.
While I'm no engineer, I don't think this is true... as discussed before a properly tuned modern two stroke needs back pressure to produce power... while it might be true that you could get a few additional horsepower if noise were not an issue is possible, I just don't see how.
As for getting more power, if all you want is horsepower... the kart guys are getting 70 to 75 horsepower out of a 250cc engine!! This would not be usable in an mx bike for two reasons, first and most importantly, it would break the rear wheel loose at inopportune times, and basically be unridable. Talk about a light switch!
Second reason is the pipe design parameters on a bike... by it's nature there must be twists and turns i to fit it on the frame and not have it stick out too far on either side. Plus the diameter needs to be larger in order to produce such large horsepower numbers....
Now maybe if you flipped the engine around on a two-stroke...... with the exhaust coming out the back.... hmmm...
(http://3.bp.blogspot.com/_OPLSO0zMObY/St991hTfNuI/AAAAAAAAALI/2NR1KXppNnc/s400/hondamodeld.jpg)
Check out the exhaust coming out the rear of this old Honda.... if this was built in the 1950's how come Yamaha calls it advanced on the 2010 YZF450 tank??
Ha ah, had to use that pic. ON vital
-
Sorry Eric!! :P :P
Miedos - it seems that many people on Vital only have a sense of humor when it convenient! Maybe they need to take a big dump or something!! LOL :o :o
-
Sorry Eric!! :P :P
Miedos - it seems that many people on Vital only have a sense of humor when it convenient! Maybe they need to take a big dump or something!! LOL :o :o
It's really starting to worry many, that the tide is starting to change. If ProAMA and FIM ever do switch the cc for cc rule, with a little pressure from series competition 8) , the change will be overnight.
-
I agree!
It will be like all the four-stroke fans had taken this....
(http://www.arktimes.com/blogs/arkansasblog/Image/ex%20lax.jpg)
;D ;D ;D
-
Seriously.... a bunch of the four-stroke fanatics are starting to see the writing on the wall... they're getting nervous that their handi-cap will be taken away...
I'm still amazed that when I post something intelligent on Vital that it get's ignored... yet many folks post every comment in the world on threads with stupid rumors... :-\
The number one reason that I don't post there very often.... only a little nudge every now and then! ;D ;D
-
sounds like the AMA and the 4-stroke fraternity are still denying there is a noise problem. I think it's easy to fix put a f@#$en muffler on them that's actually a muffler and if it restricts the engine and causes a loss in power stiff, it's something you need to deal with if you want to ride a 4-stroke. I'm tired of getting my ears blasted out by that ridiculous amount of noise deemed exceptable >:(
-
sounds like the AMA and the 4-stroke fraternity are still denying there is a noise problem. I think it's easy to fix put a f@#$en muffler on them that's actually a muffler and if it restricts the engine and causes a loss in power stiff, it's something you need to deal with if you want to ride a 4-stroke. I'm tired of getting my ears blasted out by that ridiculous amount of noise deemed exceptable >:(
I agree 100%
-
I agree also, the noise those things make is unbearable. 130 dB wide open down a straight, not the cheating 96 they claim with no load and at 1/2 max rpm. It was the biggest change in racing when I started back up in '06 after 19 years off. Back when it was only 2 strokes, you could tell how far the rider behind you was just by the sound. Now even when they are a whole straight behind you, it still sounds like they are right on your rear wheel!! I can't even hear my bike on the starting line. It's kind of like the time I ran my street-legal Chevy Z-28 against a full-race Chevelle with open pipes at the dragstrip....
-
^ haha you need a tacho on your bike :P
-
Or maybe go military and get a helmet with a built-in HUD.