old school big bore two stroke vs. modern big bore four stroke

What are the ultimate power bikes, the old big bore two strokes or the new big bore four strokes? The CR500 and KX500 are two of the most powerful two stroke bikes ever built, while the Aprilia RSV550, Husaberg FE 570, and KTM 505XC are among the fastest four strokes you can buy.  
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2001 KTM 520MXC

The CR500AFX. Oh, and Mike's old hillclimber, DC's mad machine... Speak of him - Where is he?  
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The King Of Crumpets - Crumpet Boy!

- 1991 RM125

The old 2 stroke 500 engines are close to a 20 year old design.  That said they still make more power stock than any sized stock thumper engine offered.  Service Honda puts the brand new 500 engines (still the old design) in modern frames and they are very competitive machines.  I can't help but think the 500s could have even more power that is even more useable than if they were still being developed by the big 5 manufacturers today.  

Bill H.
Temperance, Mi
2000 CR250R
1991 YZ125

Hmmm, I'd think that ATK700 intimidator would be the most powerful.  
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Even a broken clock is right twice a day.

chudster:
Hmmm, I'd think that ATK700 intimidator would be the most powerful.

The 620 is supposed to be faster  
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2001 KTM 520MXC

bhorrigan:
The old 2 stroke 500 engines are close to a 20 year old design.  That said they still make more power stock than any sized stock thumper engine offered.  Service Honda puts the brand new 500 engines (still the old design) in modern frames and they are very competitive machines.  I can't help but think the 500s could have even more power that is even more useable than if they were still being developed by the big 5 manufacturers today.

The 500cc two stroke may make more peak hp than a Husaberg FE 570 or 505XC, but there is a lot to be said about power delivery. The last CR500 I rode just spun a lot. That said, the Aprilia RSV550 is a 550 V-Twin rated at 70hp, stock 500's don't make that kind of power.  
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2001 KTM 520MXC

bhorrigan:
The old 2 stroke 500 engines are close to a 20 year old design.  That said they still make more power stock than any sized stock thumper engine offered.  Service Honda puts the brand new 500 engines (still the old design) in modern frames and they are very competitive machines.  I can't help but think the 500s could have even more power that is even more useable than if they were still being developed by the big 5 manufacturers today.

Allen_D:
The 500cc two stroke may make more peak hp than a Husaberg FE 570 or 505XC, but there is a lot to be said about power delivery. The last CR500 I rode just spun a lot. That said, the Aprilia RSV550 is a 550 V-Twin rated at 70hp, stock 500's don't make that kind of power.

Power delivery can have a factor in certain situations, but so can "instant on".  Big bore 2 stroke's have grunt as well when they're off the power band , it may not be as broad as a 4 stroke, but it's not completely absent like a 125. The explosive power delivery may be a little much for some closed course, but they were great for cross country or big open tracks with big elevation changes and long hill climbs.  The Aprilia is rated 70hp at the crank. By comparison, in 1985 Husqvarna imported a limited number of out-of-the-box liquid cooled racers called the 500cr, these put out over 60hp at the crank, and with slight bore modifications or even adding a modern computer designed pipe, 70 crank hp wouldn't be out of the question. The frame was a single chromemoly backbone and very light. Magnesium hubs, light nordisk rims, ohlins rear suspension stock, the engine cases were magnesium as well, lightweight 4 geared transmissions, everything was to save weight. Dry weight was 97.5 kilo's...That's right, less than 100 kilo's with 60+ hp, and it could be torn down and renewed cheaply by the racer himself. By comparison the Aprilia is a claimed 122 kilo's dry, That's over 50 lbs heavier. Which bike is going to get up competition hill faster? I'd say the Husky would, and he wouldn't have needed a trained mechanic on retainer to deal the the high tech complexities, astronomically priced valves and Serdi 5 angle valve jobs. Had these companies been allowed to improve with direct injection, and use computer mapping or possibly futuristic traction control to improve power delivery, they would still rule the roost.  The fact is, 4 stroke is better for low speed demands of city driving, but the reason the companies really like em, is because they make a killing on after sales service and parts.

BTW skidoo's new snowmobile Etek 2 strokes claim better emissions and fuel economy numbers than the competitors 4 strokes. And they don't need electric starters...  

the KTM 570 2stk is/was the fast production bike ever made.if i remeber right it went like 120 from factory........ & allen the bikes you listed were 2 mx bikes & the rest were off road. i dont get your meaning
DavidS  
i take a lot of pride in what i am

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ride: 02yz426
local: north east Oregon

terrain type woods with lots of roots & rocks

http://www.dirtrodders.com/atk700/

700cc of 2 stroke

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and check out this guy's no 1 pick
http://antithumper.700hp.com/

He never even got to the ride the big water pumpin' husky I speak of...

he knows the old bikes ruled and were cheaper to opererate, by a lot  

And Maico is bringing back the 500cc heat in 2009...

http://twostrokemotocross.com/2009/02/exclusive-2009-maico-500-new-look-photos/  

Maico 620 Super-Moto.
Cooling: Water
Inlet system: Reed valve system
Exhaust system: H.G.S. exhaust system
Cylinder capacity: 616ccm
Measures: 95 x 87mm
Horsepower: 76
Carburetor: BING 55/44-205
Transmission: 5 speed gearbox
Ignition: PVL digital
Frame: Chrome Molybdenum
Front fork: White Power Extreme 50
Front wheel travel: 305mm
Front rim: 3.50 - 17
Front tyres: 120/70 17
Rear suspension: Maico Twin Link White Power
Rear brake: Brembo 220 mm
Rear rim: 5.00 - 17
Rear tyres: 160/60 - 17
Tank: 9,5 L.T.R.
Wheel base: 1480 mm
Ground clearance: 358mm
Seat height: 930mm
Weight: 101 kg  

My cousin's boyfriend is looking at a KX500. If he buys it, I'll make sure to find out if it is faster than my Katoom.  
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2001 KTM 520MXC

Model: 700 M.X.
Cooling: Water
Inlet system: Reed Valve system
Exhaust system: S.E.E.S. exhaust system
Cylinder capacity: 685ccm
Measures: 100 x 87mm
KW/horsepower: 60/82
Carburetor: BING 55/44-205
Transmission: 5 speed gearbox
Ignition: PVL digital
Frame: Chrom Molybdän
Front fork: White Power Upside Down 48 mm
Front brake: Brembo with 260 mm Wave disc
Front wheel travel: 305mm
Front rim: 1.6 - 21
Front tyres: 80/100 _ 21
Rear suspension: Maico Twin Link with Reiger shock
Rear brake: Brembo with 220 mm wave disc
Rear rim: 2.15 - 18
Rear tyres: 120/100 - 18
Tank: 9,5 Liter
Wheel base: 1480 mm
Ground clearance: 388mm
Seat height: 960mm
Weight: 101 kg  

for all out over all screaming at the top of your lungs holding on for dear life power. the 2 stroke. thats why the 500's were known widely as death machines. i want one so bad. lol. all in all i think the old school 2 strokes of anysize produced more power than newer bikes on simular size. those old bikes were raw uncut screamers.  
-Kirk 88 Honda CR250R
ride hard and crash harder

Allen_D:
My cousin's boyfriend is looking at a KX500. If he buys it, I'll make sure to find out if it is faster than my Katoom.

The KX was the least favorite of antithumper's top 10 list, mostly because you had to sort out some pinging and chassis issues, but the big KX had power valves so technically it was more advances than most...I've never ridden one so I wouldn't know