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chopped850

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Nov 5, 2008
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I'm in the assembly stage of my Norty Bobber. I want to cruise this bike up and down the freeway at 80 or so. What sprocket combo or front do I need to run with the stock rear? I haven't counted the teeth on the front but just wanted to know what you guys and gals are running up front to cruise at 80 without straining the motor. I will post some pic's of the bike later.
 
At 80 mph with a 21 tooth sprocket you will be turning 4700 rpm. With a 22 tooth about 4500 and with a 23 tooth about 4300 rpm. This assumes a stock height tire, which if you built a bobber is probably shorter than stock so the rpm's will be a little higher.

I don't think you can fit a 24 tooth without removing the chain guard on the back of the inner primary cover. You'd need a healthy motor (or clutch) to pull away from a stop with that one though.
 
It's running a 20 right now. The rear wheel is a 16" with the stock drum and sprocket combo. With a 23 at that RPM does it sound like the motor has more throttle or is it maxed out?
 
with a 130-16 rear you will need another tooth to be the same rpm as with the stock size rear tyre.
 
I run a 22 with an 110/18-80 tyre on my 850
It runs at 80 pretty effortlessly, around about 4250rpm. I think my primary belt lowers the revs slightly from standard.
It is reving high at 6000rpm. I have taken it slightly above this, maybe 6250rpm :eek:
I like to think I could just clear 115mph......but I havn't gone above 95 yet since the rebuild.
So you will need a 22 .... or maybe a 23....with your 16" wheel. (but a fatter tyre will be bigger in diameter).
Stu.
 
bigstu said:
Bill
Can you fit a 130 tyre in without the chain fouling?
Click to expand...

I know this is a personal choice matter, but wouldn't a bobber look better with a tall (19" or more) skinny tire? Years ago, I built a café racer with 3.60 x 19" tires front and back and it looked good (to me anyway)

Jean
 
Can someone please clarify what exactly is a "Bobber". As you can see by my signature I was absent from the bike scene for 20+ years. Before the big sleep the term "Bobber" didn't exist, at least not where I'm from. Since I've come back into the scene I see it's a well established term.

It seems to me it is something between a stock bike and a chopper. A chopper having a raked and stretched and altered frame (often with bondo too) and many custom parts that aren't from the manufacturer. A bobber seems to be more of a bolt on chopper, frame stock but extended front tubes and a wide rear tire and maybe forward mount controls and high bars. Kinda like the Norton Hirider idea. Can anyone shed some light on this?
Thanks,
 
RennieK said:
Can someone please clarify what exactly is a "Bobber". As you can see by my signature I was absent from the bike scene for 20+ years. Before the big sleep the term "Bobber" didn't exist, at least not where I'm from. Since I've come back into the scene I see it's a well established term.
Click to expand...


I think "bobbers" actually predate "choppers"!: http://en.wikipedia.org/wiki/Bobber_mot ... the_Bobber

Chopped 850's bike can be seen here: post23963.html#p23963
 
My understanding of a bobber is just making the bike short, narrow and simple. Little solo seat, peanut tank, narrow drag bars and shrinking the front and rear fenders. A chopper is stretched, raked, long front end, king/queen seat tall sissy bar and no front fender.

I will see what the rear sprocket is. I will look into the front sprockets and probably run a 22.
 
Thanks for the wikipedia link, as I suspected the term is loosely defined between when a bobber becomes a chopper and/or vis versa. I guess the internet has finally exposed my little corner of the world to these common terms.

Cute scoot there chopped 850!
 
I'd call that a bike in the pictures a chopper although he may have converted it to a bobber now.
 
If the pic your referring to is the green long and ape hung bike that was a chopper. It's now been deraked by Freddy Hernandez to stock rake and is now becoming a bobber. I placed a large order with Britcycle for a 22 front sprocket, and gaskets. I will post pic's later on.
 
chopped850 said:
If the pic your referring to is the green long and ape hung bike that was a chopper. It's now been deraked by Freddy Hernandez to stock rake and is now becoming a bobber. I placed a large order with Britcycle for a 22 front sprocket, and gaskets. I will post pic's later on.
Click to expand...

That's all I have to go on unless you've posted more recent pictures... :mrgreen:
 
Here is where it's at so far. For a little history lesson the frame was made in 1972 by 3 friends called GDL. These guys were working in the building behind Freddy Hernandez, Denver Dan and Mondo's shop. GDL made frames for any motorcycle engine out there. They made the frames for about 2 years and then went their seperate ways. It's a DNA springer, Biltwell CLubman bars and alien peanut tank.
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bigstu said:
Bill
Can you fit a 130 tyre in without the chain fouling?
Click to expand...

The chopper I built a few years has a 16" Harley rim laced to the Norton hub and runs a 130-90-16 Metzler ME880. It is a close fit and has a custom chain guard so it is also not an issue.
 
That's probably what a previous owner did to my bike was lace a harley rim. That's the same size tire I'm running and the chain is not too far away from the tire. I've yet to see rub marks on the side wall from the chain.
 
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