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Why are some bikes so much heavier than they should be?


redkow97

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I am very high on small-bore lightweight bikes right now.  Anything under 300 lbs. qualifies as "light" in my book, but under 200 lbs. is a different level of awesome.

Anyway, i saw a GS500 for sale for like $600.  My dad actually owned one for a while, and I rode it frequently.  If it weighed 100 lbs. less, it would have been a supremely enjoyable (and less sluggish) machine.

...so why doesn't it?  What is making GS500's and EX250's weigh over 300 lbs?  I understand that the price-point demands a steel frame, but dirt bikes don't weigh 300 lbs.  I actually scoured the internet for a few minutes trying to find the weight of an EX250 engine - I wanted to see if it would be a good fit for an older (and almost free) dirtbike frame with a blown engine.  I don't remember the exact weight, but the EX250 engine ways A LOT more than you think.  Again, why?

The simple answer to all these questions is probably "Just build a 250cc supermoto, or grow a pair and buy a 450," but kid #2 is set to arrive this week...  Plus I wouldn't mind a bit of a project.  There has to be a cheaper option - a way to make an EX250 lose weight, or something else that is lighter in stock trim.

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Lots of engineering compromises to 1. meet a price point. 2. Provide the reliability and maintenance intervals 3. Provide the load carrying capacity.

So you get mild steel frame, beefy subframes, large oil sumps, substantial engine walls, large steel gas tanks, etc...

MX or supermoto bikes under 300# have none of that and cost considerably more than GS500s or EX250s. Sure you could drop 50# from the EX250 but it would cost alot.

But I agree with you on the lightweight bike, that is why I got the DRZ400SM. Its not sub 300# but it does provide a subframe and reasonable maintenance intervals and is about 50# lighter than the Ninja.

 

Craig

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I like the DRZ400 SM, but people seem to over-value them on the used market.  And as you note, it's not quite "light."

 

I'm currently cruising eBay.  Considering buying a chinese 200cc engine and putting in into an older 2-stroke dirt chassis.    There are TONS of cheap 2-strokes with a front disk brake and "needs top-end rebuilt" on craigslist.    If the engine is the right price, and it will fit in the frame, 200cc (air-cooled) is the upper limit for Formula 1 with OMRL.  Plus it would be able to get out of its own way on the street.  Probably not the highway, but I can live with that.

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$

cast vs forged parts

cheap light strong. pick 2

it's pretty funny because in bicycles it's opposite and roadies weigh less.

They need to be strong enough to handle speeds they're capable of  not just legal stuff hence dual front discs.

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Gs500 is heavy because it's a budget shitbox. That means a double cradle frame made from cheap, durable, heavy steel and a rehash of a motor engineered in the 80's, possibly 70's... the 500 is just a rebore of the 450..The gs500 was obsolete before it even went to market. Antiquated casting techniques, ancient metallurgy, a design that was more utility and durability oriented than performance and weight savings. It does what it was designed to do well, and that is to be cheap reliable transportation that is easy to work on, but is no quicker than a ninja 250.

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16 hours ago, redkow97 said:

I like the DRZ400 SM, but people seem to over-value them on the used market.  And as you note, it's not quite "light."

 

I'm currently cruising eBay.  Considering buying a chinese 200cc engine and putting in into an older 2-stroke dirt chassis.    There are TONS of cheap 2-strokes with a front disk brake and "needs top-end rebuilt" on craigslist.    If the engine is the right price, and it will fit in the frame, 200cc (air-cooled) is the upper limit for Formula 1 with OMRL.  Plus it would be able to get out of its own way on the street.  Probably not the highway, but I can live with that.

Agree on both counts on the DRZ400SM. 

Sounds like a fun project. I've thought about dual sporting a crf150f or similar to get an inexpensive light weight off road bike. I hate trailering hence the reason for converting :D

 

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9 hours ago, zx3vfr said:

I love my 460# gsx s750. Steel frame, 10 year old motor. 103hp. 0-60 faster than your average 100k+ sports car.

easy riding due to added weight, doesn't get bounced around like an rr

Same with my heavy ass bandit. Motor was designed in the 80's (but was arguably the hottest shit on the road back then) stiff, heavy steel tube cradle/perimeter frame. Hauls balls and stays very well planted but handling isn't light like an ss or rr.... But I'll trade the lighter control input for more comfort and stability at speed. 

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27 minutes ago, Isaac's Papa said:

If a lightweight RR is being bounced around, it needs someone to adjust the suspension. You shouldn't feel like you're on a rodeo bronco. 

Don't have that kind of time to dick around setting up a suspension on a bike designed for a 130# little European/Japanese person. 

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