How do I get there from here

[Purplezinger]

Our son was in the Air Force and stationed in England for 3 years during the early 80's. Summer 83, we planned our vacation around going to England, doing the "tour", visiting our son, etc. We were in London at Trafalgar Square standing near the fountain with traffic and people everywhere. Over the din of noise I hear a bike. It was WFO coming down through the gears, he came in from a side street, merged with the traffic, went past us leaned over, rocketed into another side street and disappeared. Amazing riding skill, yes, but what made it incredible, his girl friend was on the back! Rossi couldn't have done it any better. Fearless maybe, but they have skills.

 

[Samuraiace]

I'll let you guys know when I'm comming up and maybe we could meet and grab lunch and a drink

Sounds like a plan to me Gordon, hopefully I'll have my XS on the road by then.

Your neighbor sounds like he was a really cool guy, oh to be a racer of the early years.

 

[Samuraiace]

So how much speed and accel do you guys think can be achieved with rate reduction?

Xander and I were having a conversation about this thought the other day and we figure it's better to lose ten pounds off the gut then off the bike. So how much of a gain is there?

I mean any weight lose will make for better maneuverability and speed.

 

[BigJimmyW13]

I mean any weight lose will make for better maneuverability and speed.

Funny you say that. A friend of mine and I were talking about this the other day. He wants to find an XS and build a cafe racer out of it. He was asking me what he could leave off to cut weight out of the engine. Where he could lose a couple ounces here and there..... I told him to lose about 50lbs... His response. Touche, good sir.

I don't know how much of a difference it would make, but cutting 6 ounces off of the bike won't help as much as the rider losing 10lbs.

 

[gordonscott]

This could turn very interesting I remember that for every drop of 10deg F you would gain like 1 hp? Dropping weight will make your bike quicker. There is static mass and rotational mass and a drop in each will get you to your destination faster. I “think” that there is a rule of thumb for racecars that for every 10 lbs lost the power to weight ratio is like a 1 hp gain? Ok so lets get to Google and find some facts http://www.dragsource.com/index.php?navselect=calculators&calctoview=7 and http://www.ajdesigner.com/phphorsepower/horsepower_equation_power_to_weight_ratio.php By the way I have dyno tested a stock XS in pristine condition with perfect compression and it was 42.5 at the rear wheel. Weight of bike (77) i believe is 426lbs.

 

[Patches]

Funny you say that. A friend of mine and I were talking about this the other day. He wants to find an XS and build a cafe racer out of it. He was asking me what he could leave off to cut weight out of the engine. Where he could lose a couple ounces here and there..... I told him to lose about 50lbs... His response. Touche, good sir.

I don't know how much of a difference it would make, but cutting 6 ounces off of the bike won't help as much as the rider losing 10lbs.

Big Jim, you are so right, bud. There is a formula somewhere out there on the interwebs that I ran across once upon a time. It basically calculated how much horsepower is required to accelerate and object at a certain speed in 10lb increments. It was very interesting. I have some vintage mopeds that my finance and I use to cruise around the neighborhood and visit friends. Mine will go 4MPH faster with her riding it being that she is 60lbs lighter!!! It reminds me of guys I raced against that would buy carbon fiber wheels, titanium frames, drill speed holes, etc but at the same rate they were obese (20% over their ideal body weight). Look at the world of hight end jockeys. These guys are built like 12 year old school girls but they are light and can make that horse hall ass.

 

[emzdogz]

plus, lower rider weight would mean lower CG (I think), which would make for a nicer ride.

 

[Samuraiace]

Hmm...This is one way to lower ride hight.