HP On rebuild

[cpotts454]

Im considering what kind of horsepower I can make with a big bore rebuild. First, how much hp does one make stock and a can you give me a rough estimate on how much horse power I can make with a big bore kit + hot cams + polish and port.

I am just looking to do something new to my bike to get me excited about riding it again. I figure I can do all this work for sub $2000 range, and I am really interested in being able to get the front wheel off the ground. I kind of want a sleeper.

 

[pyrocentric]

Here are some dynos
http://www.xs650.biz/p/28/1428/tuning

 

[xstwin]

With the cnc head you"ll need($1200) and many other parts $2000 doesn't go very far.I think stock your looking around 48 hp and I have heard upwards of 78 hp with the modified head et;however horses in the 70's is gonna make your bike explode-implode,the motor just wasn't designed to do that.If you want a monster or something fast as hell but yet classic your better off buying something else like a mid 70's ducati 900ss and just cruising on your xs. But that's just my opinion.

 

[Sundie]

or a cb750.

 

[cpotts454]

Agreed... But part of the fun is pushing the limits. Your right, if I wanted a fast bike stock I would buy a crotch rocket. I just want a bike no one would think is fast and blow them away. I wasnt thinking about a CNC head.. Whats it cost to have someone port and polish a head now and days?

 

[floris]

And this kinda thoughts just crossed my mind as well.
Why you ask ?

Because its just a heck off fun to do so. (except the exploding thing offcourse)

I just build my bike up by example of mule. (the one with the magic black wheels)
And the next fase is to get as much HP as possible, without the use off a turbo that is.

I'm looking at a rephased engine with a displacement of 880 cc's.
And doing all the stuff that is neccesary, hot cams and so on.

Now i am wondering how to increase the rpm's of it.

I'm struggling to get about 80 HP out off it.

Anybody ???

Greetzzz.

Floris.
The Netherlands.

 

[GreasyC]

People have already been pushing the limits of the xs650 for four decades and they're pretty well mapped out at this point. People who've pushed it over 70 horsepower experienced broken clutches, transmission, and cracked engine cases. Sure you could re-engineer tougher versions of all those but by the time you've custom made the entire engine case, transmission, clutch, replaced the barrels, pistons, rings, valves, springs, and cam I don't think it's an xs650 anymore. It's just a custom made engine that for some reason uses a very old design.

 

[floris]

And i think your so right about that.
It's probably not possible to push the boundry of 70 HP.

Well, i'll just have to settle fore that.
The new frame is about 10 K lighter than the original.
A lot of original stuff can be waisted.

So i'll end up with a bike thats lots of K's lighter than it used to be.
That, with somewhere around 70 HP will give tremendous torque.
So i don't think i have to worry a lot, me being left behind against
a Ducati monster, Aprilia Mille or comparable to these kinda bikes.

What are you all out there, thinking about this statement.

Please let me know.

Grrreetzzz, Floris.

 

[haxto]

And i think your so right about that.
It's probably not possible to push the boundry of 70 HP.

Well, i'll just have to settle fore that.
The new frame is about 10 K lighter than the original.
A lot of original stuff can be waisted.

So i'll end up with a bike thats lots of K's lighter than it used to be.
That, with somewhere around 70 HP will give tremendous torque.
So i don't think i have to worry a lot, me being left behind against
a Ducati monster, Aprilia Mille or comparable to these kinda bikes.

What are you all out there, thinking about this statement.

Please let me know.

Grrreetzzz, Floris.

Humm, Looks like the WHOLE XS community "all out here" were just too breathless to respond!

 

[Conrad Russell]

I'm not breathless and like ass holes everyone has an opinion.Having owned a Ducati 945,big cube V-twins ect.my opinion is if you want to cruise buy a cruiser,want to be cool build a chopper,100 plus mph wheelies buy a crotch rocket.My XS with complete Pamco kit,custom intake pipes,baffled straight pipes runs great for what it is.With the 8" over springer it is effortless to ride,never a worry,hands free at any speed.The biggest thrill isn't the power,it's when it's parked at the store or any where and people cant help but stop and check it out.All that being said,build what makes you happy,if it blows up there are plenty of replacement motors out there.

 

[FB71]

The biggest thrill isn't the power,it's when it's parked at the store or any where and people cant help but stop and check it out.All that being said,build what makes you happy,if it blows up there are plenty of replacement motors out there.

Exactly my thoughts!

 

[TheBooger]

hughs handbuilt slight hell build was pretty quick. theres tons of info out there on what he did. I'd start with his build as a template on how to do things right

 

[Cafe Murdock]

And this kinda thoughts just crossed my mind as well.
Why you ask ?

Because its just a heck off fun to do so. (except the exploding thing offcourse)

I just build my bike up by example of mule. (the one with the magic black wheels)
And the next fase is to get as much HP as possible, without the use off a turbo that is.

I'm looking at a rephased engine with a displacement of 880 cc's.
And doing all the stuff that is neccesary, hot cams and so on.

Now i am wondering how to increase the rpm's of it.

I'm struggling to get about 80 HP out off it.

Anybody ???

Greetzzz.

Floris.
The Netherlands.

Use a cross plaine crank for higher rpms but they vibrate more or go forged crank