Specialized Hardrock

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SEAKbiking

New Member
Feb 18, 2011
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Alaska
Ok, so I have a Hardrock that is about an '08 and I'm thinking about putting 4 Stroke 49CC Bike Engine Kit this engine on it. It looks like there is enough room inside the frame but the down tube has me a little worried about it's oddly wide size (trapezoidal shape and 2" wide). I don't have a tape measure handy right now but if anyone who has worked with these could give me some tips that would be greatly appreciated.
 

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wheelbender6

Well-Known Member
Sep 4, 2008
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TX
You have chosen well. The Specialized Hard Rock is the best selling mountain bike in history. You can deal with the wide down tube by using an automotive muffler clamp or ordering an oversized front engine mount from one of the vendors on the site.
 

SEAKbiking

New Member
Feb 18, 2011
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Alaska
Thanks for that bit of advice.

Also, I didn't know that about the hard rock. I'm glad to hear this because my buddy keeps telling me how I bought some over priced cheap chinese junk and I should of bought a schwinn instead.
 

The_Aleman

Active Member
Jul 31, 2008
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I agree, I highly doubt a 4-stroke will fit in that frame. Specifically, the intake box and carb prolly won't clear the top tube. If it was mounted at a severe angle, it might barely fit, but the 4-stroke should be mounted level, or as close to it as possible.

IMHO, Hard Rock is a pretty decent candidate for a 2-stroke, tho.
 

SEAKbiking

New Member
Feb 18, 2011
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Alaska
Ah, I was trying to stay away from a 2 stoke for the convenience of not mixing gas and for the fact I live in a VERY hilly area. I live on a small island town built on a mountain so there really is only fairly flat road and that's the main street, everywhere else has very steep and fairly long hills.
 

The_Aleman

Active Member
Jul 31, 2008
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el People's Republik de Kalifornistan
That all depends on gearing and tuning, SEAK, but for the most part a 66cc 2-stroke makes significantly more power than a 49cc 4-stroke. More displacement and twice as many power strokes per revolution. 4-stroke might have it beat on low-end torque, but I put my money on a 2-stroke's midrange and high-end power.
 

LS614

Active Member
Dec 22, 2009
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CT and MA
I like the idea of a 4 stroke, I'm upgrading to one. If you don't have the funds for an ez kit (which would probably not fit anyway) then get a dax rack mount. That is probably the best affordable 4 stroke kit on the market. An in frame mount seems unlikely, I do love the hardrocks though! I think mine is an '06 or '07