xs650 engine bore build help

[corgoth]

I have a xs650 all stock but this summer I want to put $6,000 into the engine alone and build this bike to put out the best power, torque and speed.... any information or help or ideas would be very helpful this is my first build but I am serious about doing it this year

 

[arcticXS]

As underwhelming as the stock XS engine is, spending all that cash on the engine alone, is hardly the best move, (if the plan is to leave the bike otherwise stock)

Brake and suspension upgrades should be first priority, then some basic engine upgrades like ignition, carbs, filters and exhaust. Then look at shedding weight, the stock XS has some ridiculously heavy oem components (front brake discs, steel fenders, rear wheel, 530 chain where 520 would be fine, foot pegs and controls, late model indicators are real heavy too, get some XS2 ones)
When all this has been adressed, you can get on with engine upgrades. Jerry Heiden in The Netherlands ("Holland") offers 85 mm big bore kits, giving 840 cc, or even more with a stroker crank. Then Craig Weeks offer the CNC porting of your head through 650 Central. Spending $6000 should be no problem....But look at brakes and suspension first!

 

[CDNTX650]

Keep all those massive cc's in mind when your trying to drive the thing in warmer weather....

 

[DIRTY DOG]

I have a xs650 all stock but this summer I want to put $6,000 into the engine alone and build this bike to put out the best power, torque and speed.... any information or help or ideas would be very helpful this is my first build but I am serious about doing it this year

I would get with hugh's handbuilt,and have a crank done get a good cam and a 750cc
big boore kit a good set of vm36 carbs a set of hugh's exhaust pipes pamco ign. and pma charging system should be good to go.

 

[goodgollyjosh]

I have a xs650 all stock but this summer I want to put $6,000 into the engine alone and build this bike to put out the best power, torque and speed.... any information or help or ideas would be very helpful this is my first build but I am serious about doing it this year

It's funny how all the little things start adding up in the engine build process. I am right smack in the middle of it, money goes fast. Since the engine is my main interest in my build, it is where I chose to spend most of my money as well. I am excited to see your build; please blog it, or start a thread when you begin.

 

[Scrambled]

As underwhelming as the stock XS engine is, spending all that cash on the engine alone, is hardly the best move, (if the plan is to leave the bike otherwise stock)

Brake and suspension upgrades should be first priority, then some basic engine upgrades like ignition, carbs, filters and exhaust. Then look at shedding weight, the stock XS has some ridiculously heavy oem components (front brake discs, steel fenders, rear wheel, 530 chain where 520 would be fine, foot pegs and controls, late model indicators are real heavy too, get some XS2 ones)
When all this has been adressed, you can get on with engine upgrades. Jerry Heiden in The Netherlands ("Holland") offers 85 mm big bore kits, giving 840 cc, or even more with a stroker crank. Then Craig Weeks offer the CNC porting of your head through 650 Central. Spending $6000 should be no problem....But look at brakes and suspension first!

I agree with Arctic %100 . If you do anything, improve your brakes and suspension first . No sense having HP if you can't really use it .

 

[corgoth]

Sorry For not elaborating earlier I didn't think this post was going to get any replies but much to my pleasure I was proven wrong and thank you for all the input from everyone what I want to do is turn it into a soft tail bobber if you go under youtube there is a bike I want to model mine after its the xs650 bobber/cafe it's white the motor alone I want to do 6 tops into the motor and get it around 80 hp I know this burns up the rear quite fast also I was wondering if anyone has ever seen a single sidearm such as ducati uses and to put it into a bobber rear end I think this might look cool (again this is my first bike so any help is greatly appreciated )

 

[corgoth]

Also I want to rephase the motor to ether 277° or 270°

 

[650Skull]

If your realy serious then weight is a major factor. Read this comprehensive thread on the Club racer from Australia and what they did to save weight and strengthening parts for the horsepower.

Read an article from Craig Weeks recently. Has some very important info on horsepower and compression ratios. Scroll down to the artical

650 Performance. How the Best Ever XS650/750 Engines were Built
This is the race guide for The AMA race tuned 650/750 bikes

High Ratio Primary gears. Aussie club again and again scroll down about 3/4's of the way down the page.
At the top of the page is the sump extension so the oil doesn't get sloshed around as much putting extra load on the crank. Can only be used with a Standard frame 74-79

 

[arcticXS]

Sorry For not elaborating earlier I didn't think this post was going to get any replies but much to my pleasure I was proven wrong and thank you for all the input from everyone what I want to do is turn it into a soft tail bobber if you go under youtube there is a bike I want to model mine after its the xs650 bobber/cafe it's white the motor alone I want to do 6 tops into the motor and get it around 80 hp I know this burns up the rear quite fast also I was wondering if anyone has ever seen a single sidearm such as ducati uses and to put it into a bobber rear end I think this might look cool (again this is my first bike so any help is greatly appreciated )

If you want a bobber with 80 HP, then you should start with another engine. I would suggest using an engine from a 1200 cc Buell, as they already have that kind of HP, with no further mods needed, then get an aftermarket bobber frame for a Sportster. Alternatively, use Buell heads and pistons in a 1200 Sportster, and modify the frame to your taste.

In any case, this may be cheaper than spending $6000 on an XS engine, which will not give more than 60-65 hp at best, in a street bike. I have spent about $5000 on a rephased crank with special rods, 750 cylinder kit, Shell #1 camshaft, new carbs, programmable ignition and a lot of small items needed for a rebuild. And If I manage to get close to 60 HP at the rear wheel, I will be more than happy.

 

[hotdog]

If you want a bobber with 80 HP, then you should start with another engine. I would suggest using an engine from a 1200 cc Buell, as they already have that kind of HP, with no further mods needed, then get an aftermarket bobber frame for a Sportster. Alternatively, use Buell heads and pistons in a 1200 Sportster, and modify the frame to your taste.

In any case, this may be cheaper than spending $6000 on an XS engine, which will not give more than 60-65 hp at best, in a street bike. I have spent about $5000 on a rephased crank with special rods, 750 cylinder kit, Shell #1 camshaft, new carbs, programmable ignition and a lot of small items needed for a rebuild. And If I manage to get close to 60 HP at the rear wheel, I will be more than happy.

I have to agree - get either a sportster based bike or alternately a Yamaha Bolt - you'll be streets ahead....

 

[XSLeo]

$6000 will buy a lot of speed if you get a crotch rocket. Spending that kind of money on an xs engine can be done but at 80 hp it won't last long on the street.
Leo

 

[oldbiker]

I have a xs650 all stock but this summer I want to put $6,000 into the engine alone and build this bike to put out the best power, torque and speed.... any information or help or ideas would be very helpful this is my first build but I am serious about doing it this year

.......................... hi you could supercharge it as a guy in australia has done,,, he may even be on the aussie site to look at regards oldbiker

 

[650Skull]

From the link i posted above.

wise words from Craig Weeks at 650Performance.com

650Performance.com is the go-to spot if you want to build big power into your Yamaha XS650 motor safely. Says Craig...

"Now that people are putting their modified engines with the CNC'd heads on the street and race track I'm becoming a bit uncomfortable with what I'm hearing about how radical some of their modifications are.

The XS650 cases, clutch and transmission were designed for an engine that would make around 42 rear wheel horsepower (RWHP). When Yamaha was in the middle of the dirt track wars in the '70s, the engines built for Kenny Roberts and others on the factory team (as well as the best privateer engines) were putting out right around 70 RWHP and reliability wasn't generally a problem. The best engines built by Bud Askland, Harry Lillie and others were inspected after every race but would typically last a half season or more before any major replacements were required. Compared to the BSAs, Triumphs and Nortons this was a real luxury.

When Harley took the next step in XR750 power Yamaha responded by pushing the XS650 power envelope even further. With Tim Witham in charge of development the XS reached the 75 RWHP threshold with stock head castings. While the bikes were rockets, things began going wrong. Broken transmissions, cases and connecting rods were the worst, but clutches and valve trains were breaking too.

You probably know the story about how Yamaha's response to this was the fabled OU-72. What some people have forgotten is that the OU-72 didn't just have a sophisticated revised XS650 cylinder head with previously untouchable flow numbers, it was also accompanied by all the reliability tricks Tim Witham had learned - strengthened cases, Webster transmissions, thickened and deeper clutch baskets, alloy rods and a host of other upgrades.

The first XS engine that Harry built for me was exceptionally powerful. It was a full AMA-spec build and was the strongest XS engine I've ever run.

After about a half year of racing it at Sears Point with AFM another racer was looking at the bike and pointed out a small crack in the cases, right in front of the cylinders around the oil up tube fitting. When Harry dismantled the engine the cracking was found to have extended all the way down into the cases and around the crankshaft webbing.

We tossed those cases and took the edge off the rebuild by lowering the compression a little bit, richening the Lectrons a little bit, advancing the cam a little bit for more midrange, etc., and it dyno'd out at 71 RWHP. Perfect. Since then I've always run my engines in a state of tune that gives them 69 - 72 RWHP and I've never had a catastrophic failure.

The point of this message is that the stronger cases, clutch baskets, etc. aren't available today. They are either worn out, broken or lost. And the specific lessons learned from piles of broken parts about how to modify your engine to live happily at 75 RWHP are long forgotten by the men who developed them.

If you have a good OU-72 head, or you are one of the people who recently received one of the new CNC'd heads (or you have any head that really flows well), you have the potential to reach 75 RWHP.

For the reasons above, I caution you to resist the temptation to raise the compression a bit higher than discussed in my XS engine modification guide (see 650performance.com if you don't know about this), or tune it a bit sharper, or bias the power curve to toward the top end, etc.

If you have a solid 70+/- RWHP or less your bike will run really hard on the street or race track and (if it's put together correctly) will be reliable.
Remember: 69 - 72 RWHP = reliable. 75+ RWHP = expensive things break."

The images above and to the left here are the work of Gordon Calder, an obviously talented photographer who has created many motorcycle related works of art by concentrating on light/shadow, detail and contrast.

Mr. Calder obviously has a keen eye for dramatic images where most of us only see the big picture, and this, among other talents, enables Calder to tease out the art in industrial technology.


80 HP may be obtainable but nothing will hold together

 

[corgoth]

I was thinking about doing a Heiden 890cc kit and switching the camshaft I sit about 6 ft 3 at 190 lbs so the power to weight ratio of a motorcycle throws me off compared to a car weight -hp ratio I know this is going to sound dim and dull possibly but I don't need something fast like a GSX-R1000 just something that is quick and fun

 

[CDNTX650]

They arent even a slouch in good running stock trim...a cammed 750 with some better carbs would probably be a good fast reliable bike.

Posted via Mobile

 

[Scrambled]

I weigh 275lbs or so and my stock 650 still pulls me around no problem . I agree with the other posters that said you are better off spending your 6 grand on a bigger bike if you want more power . Hell, for 6 grand I could buy 3 or 4 stock bikes that could do 3rd gear clutch wheelies .

 

[JP50515]

I second the 750 move....CB750 that is... You're looking at the wrong bike if you want big gains. The CB750 (DOHC) versions stock are quick enough to throw you off the seat on take off...ask my buddy about his first time riding his! The 750 is my suggestion simply because you've moved into a 4 cylinder sport bike type engine with stock HP close to a maxed XS650...6000 in that bike will go a lot farther and get you moving a lot faster than on an xs.

 

[Scrambled]

Why not buy a newer bike that has a V4 liquid cooled engine ? I see low miles 750 magnas asking price $1500 on kijiji and that is certified . Lots of fire breathers out there for cheap .

 

[corgoth]

I was actually on kijiji yesterday and I found a bike called a "honda valkyrie" they have the rune edition and I think those would be cool to turn bobber