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Old 12-23-2012, 07:03 AM   #8
Seavoyage OP
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Joined: Dec 2011
Location: San Francisco
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Quote:
Originally Posted by Gham View Post
The most glaring upgrade would suggest suspension, the CR has more travel but might need a re-valve or lighter spring but the components are fairly comparable.
Maybe upgrade the Kayaba forks to a Pneumatic Spring Fork?:



Quote:
Originally Posted by buls4evr View Post
Yamaha has really upgraded 2 stroke technology but uses it only on their snow machines not on bikes. Perhaps Husky's new 300 2T in 2014 will get them all thinking about this again. just watch the endurocross circuit or chk out the weekend warriors on Michigan single track. Many of them are still keeping or going BACK TO 2Ts. Why not run a 200 KTM? It seems to meet all your needs and already has good torque.
I tried to do some research on the Yamaha 2-stroke snowmobiles. I couldn't find a Yamaha 2-stroke model in 2012 or 2013. Yamaha may currently only offer 4-strokes.

The current technology developments on 2-strokes are turbocharging and EFI. We'll throw it electric start . In 2009 TM Racing announced they would release a EFI 2-stroke... but as of today TM Racing 125/144 still have the Keihin PWK 38.

Why not run a KTM200? Read on... (besides we already have one but want to constrain ourselves play within the F.I.M. EWC E1 rules).
  • Enduro 1 (E1) – 100 to 125 cc 2-stroke or 175 - 250 cc 4-stroke. The E1 class is dominated by 250cc 4-strokes.
  • Enduro 2 (E2) – 175 to 250 cc 2-stroke or 290 - 450 cc 4-stroke. E2 riders won't run the 200cc against the 450cc 4-strokes; but some prefer the 250cc; which does spin up faster and has a more 'MX hit' than the 300cc.
  • Enduro 3 (E3) – 290 to 500 cc 2-stroke or 475 - 650 cc 4-stroke. Christophe Nambotin won the 2012 E3 Class on a KTM300EXC; David Knight ran a KTM500EXC. Husaberg campaigned Joakim Ljunggren on a TE300 and Oriol Mena on a FE501/FE450. KTM/Husaberg runs 4-strokes next to their 2-strokes to target the 4-stroke market. Aigar Leok rides a TM 300EN. Sebastien Guillaume on a GasGas EC300.
Despite having done well with the TE250 (E1) and TE310 (E2),Husqvarna did not have a 2012 factory presence in E3.

Examining the current EWC and Extreme series.: The E1 class is dominated by 250cc 4-strokes since 2-strokes are limited to 125cc. E2 class is split between 450cc 4-strokes and 250cc 2-strokes. Similar to E2, EnduroCross has become the domain of the 350 4-stroke.

But in the E3 class and Extreme/Hard series, despite the availability of >450cc 4-strokes, this class is dominated by the 300cc 2-strokes.

Unlike the late 70's and early '80s when there was frequent experimentation through trial & error, and rapid advances in both 2-stroke engine and suspension development, dirt bike technology in the last 20-years has plateaued. Most of the recent developments have focused on utilizing lighter or stronger materials to permit designs with more efficient mass centralization around the engine, or repositioning the motor to improve handling.

2-stroke engine development have been limited since the perfection of 'snail' exhaust chamber design, exhaust power-valves, reed blocks, and flat slide electronic TPS and Accelerator pump enabled carburetors became available and affordable (economies of scale) to the general market. One motorsport that continues to push the development in 2-stroke engines is karting: SwedeTech and link to National Karting News article on the CR125 Moto class.

The new frontier for 2-strokes is in EFI, and turbocharging. EFI R&D is driven by stricter emission regulations. Public perception of emission issues from 2-strokes still favor EFI R&D for 4-strokes. Turbocharging may not be viable for dirt bikes due to additional weight and heat generation. We expected TM to release an EFI 2-stroke in 2009. There's rumour of Husqvarna EFI 2-strokes in 2014.

Honda's release of aluminium twin-spar frames in 1997 followed by Yamaha in 2005 against KTM/Husaberg retention of CrMo single backbone frames imply that the verdict isn't out on the advantages of aluminium frames. Disadvantages are: additional weight to achieve equivalent torsional strength, which resulted in excessive rigidity in the early over-built aluminium frames.

Rising linkage single shock rear suspension have reached the limits of development, and are subject to the 'Law of Diminishing Returns'. Suspension evolution seems to reveal the open-cartridge forks are better suited for off-road, and the closed-cartridge forks are generally preferred in MX. Many of the suspension improvements are already known (reducing unsprung weight, geometries, rigidity, reducing stiction), but availability to the market is constrained by cost. The KYB Pneumatic Fork Spring and associated technologies as used by Fox in MTB shocks, are still pending market response.

I find the GasGas EC300 easier to be a 'lazy rider' over the KTM 200EXC; but that doesn't mean faster. The CR125R sorted out may be a faster woods bike than the KDX200 we've owned; we shall see...

Quote:
Originally Posted by tjanson View Post
Did you pick the CR over a YZ simply because of the California regulations?


////Love where this is going. I have been thinking about a lightweight 2 stroke to boost my woods smiles to miles ratio.

Conventional wisdom says KDX, but I want a) super lightweight and b) a project!. I've looked at DSing a KX100 - they are only 157 lb (rivaling a trials bike!) but they don't have full size wheels (19/16),

The Husky definitely seems overweight- it's about the same as a KDX200 /220 @ 220 lb. Why bother with the Husky, when you could throw some KX USD forks on a KDX, get a suspension revalve, and have a much more tractable engine ad the same weight for way way less than a new Husky.
We wanted to come close to the current Husqvarna design: 2-stoke engine with exhaust powervalve, and reed-valve intake; CrMo single-backbone steel frame; 6-speed transmission.

The 1997 CR125R has been described as the most powerful CR125 motor, and is the last year of the 1992-1997 CrMo steel frame, In 1998 Honda adopted the aluminum frame (1997 for the CR250R) and a 5-speed transmission.

The YZ125 is still imported to the US.
Quote:
the '96 to '01 steel frame YZ125 (Green Sticker: Ride CA OHV all-year) and '05 to current '13 aluminum frame (Red Sticker: Only ride CA OHV Nov-May) are the most popular 125cc for Enduro conversion. '02-'04 YZ125 had a 5-speed transmission. The current PSS suspension has received great reviews
Although the KDX200 is a very capable woods bike, it wasn't a close comparison to a WR125. KDX200/220 are disappointingly heavy compared to a KTM200. We've owned three KDX200, with one converted with a KDX250 USD front end. The 1995 & newer transitioned to a perimeter frame, The KDX200 motor remained the same from 1989 until the last year of US import: 2006 (due to emission restrictions). Source: The Life and Times of the Kawasaki KDX200.
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Seavoyage screwed with this post 01-05-2013 at 04:04 PM
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