Power

[XSLeo]

Me, I just used Mike's 750 big fin kit. 80 mm pistons.
.80 mm isn't an option. The over bores for the stock cylinders are in .25 mm increments. as in first over is .25, second over is .50, third over is .75 over
They list one over size for the 750 kit of 81 mm.
Leo

 

[willy]

if i remember correctly it was bored out 81 mm pistons, yep and it ran perfectly on stock carbs and jets, ................

 

[arcticXS]

In my opinion, the XS650 needs every extra horsepower possible to tickle out of it, without compromising reliability, driveability and economy too much. In stock form it is one of the best looking Japanese bikes ever made, but just too slow, too heavy and don't even get me started on the brakes and suspension.
So a 750 kit, cam, porting, carbs and exhaust should make it a better bike for most of us, then loose 20-30 kgs, upgrade brakes and suspension and we are getting there

 

[haxto]

I agree with one member on here with the porting and polishing. That watch what you take off cuz yes these ports are definetly large enough compaired to the size of the valve. I've found in my experiences that wether it be a car or snowmobile or bike any motor that the simplest thing you can do is first get in there and smooth out the bends. Don't take to much off just smooth it out. Then the most important part most people overlook is "port matching". You want to have the exact same size hole on the engine side and manifold. Easiest way to do this is place just the gasket or mounting clamp on without the exaust pipes or carbs use a marker to color in what part of the port is smaller or larger than the gasket and grind that down. The objective is too have a smooth flow from engine to exhaust. You can gain good power just from this by eliminating flow resistance.

I was just reading this thread and KNEW this is something I've really got to get done. Because I happened to have two pictures that perfectly demonstrate what 81-650chopper is referring to, thought I should throw em in here.
I took these immediately after mounting my new JBM Intakes. The view is looking into the carb holders, you'll see two bright white circles, the inner circle (smaller) is the port openings, or more specifically, the surface of the port openings that does not match to the the intakes, causing considerable turbulence I would think.

 

[gunk]

Howdy from The Great White North . Just signed up . excellent site.
I'm putting together a /76 zs650 C. Kevalr clutch, Neider cam cleaned up ports, hi vol. oil pump,gearing up for better hiway speed/lower revs, Pamco Ign. 750 big bore kit.
My prob is zero instructions with the big bore kit. So I will chack all ring end gaps and piston to cyl clearances based on Yam serv. manual. Does anyone out there know if these specs are correct for the kit? I'm a hesitant to put it together until I can confirm this!
Finding carbs to finish ot off is a bugger on Our side of the border. I will try to contact 650 central for a set of Mikuni VM's . I heard they are good folks to deal with.
jUST got a 2nd. rough XS1 with 2 motors.for some old honda cb750 parts.looks like next winters project is already tee'd up
Bikes; xs650c/xs1/73rd350/4 rd400's/77 xt500/79cr250/02 buell m2

 

[650performance]

Hey Gunk ...

By all means talk with Michael Morse at 650 Central. The VMs will work perfectly with your engine and Michael can talk you through the process. I don't know about the Neider cam ... there are well proven designs available through Megacycle and Hoos Racing that are street friendly while still providing a good bump in power.

The best advice you can receive from Michael is what engine components will work the best together. The engine is an air pump system and there must be a balance between all the bits you choose, from carb filters to the tip of the exhaust.

You don't actually need a hi-vol oil pump. The stock pump works just fine, even for XS racing engines. Ring end gaps are simply a function of ring type and bore and Michael can also advise you on that aspect of things.

Good luck.

 

[gunk]

Thanks for the advice 650E I have a set of ascot pipes which I pulled apart and put in some FMF 4 stroke mx baffling to make them more street friendly as The Law up here is now on a sound test crusade against bikes due to the cruiser straight pipe throttle tuner types. 250 bucks for 1 decibel over the limit!So It;ll breathe fairly decent. We have a hell of a time getting some 650 stuff up here Mikes XS won't ship to Canada anymore.
As there is xs650direct.com an affiliate. Unfortunately We don't get 1/2 the gear You get there. I'll definetely contact 650 central for advice on Jetting.
thanks eh.

 

[willy]

yes, and have no cooling issues..cylinder wall very thin when bored out 900cc its only a mod for racing, wouldnt do it for a road bike...

 

[willy]

why not buy a busa. should meet your needs..

 

[hooser]

Hello, here is a least expensive way to go..I sent a couple of dynos I had, have more just can't find them right now. dynos. 700 kit, shell # 34mm carbs and free flowing head pipes. 56+ same configuration with a 750. 59+ ( I was running a little rich so after adjustment I got another 1.5 hp+. The only head work on the 2 dynode were matching the intakes to the spigots and just cleaned up the exhaust casting marks. Rogers full race 750 makes 70hp. Email me at gary@hoosracing.com and I will look for more.
Cost . 700 set up with:
700......270.00
Shell #1 ...125.00
R/D springs...$125.00
34mm Carbs...$390.00
Pipes.MS TT pipe $90.00
Cost for 750..
sleeves 180.00
750 pistons..$$285.00 (may change)
Shell #1 ...125.00
R/D springs...$125.00
34mm Carbs...$390.00
Pipes.MS TT pipe $90.00
These are for parts alone.. More power need more head work. for 70hp we have ported head, 1mm over size valves. and bigger cam.Rogers full race 750 makes 70hp
Hope this helps. Gary

 

[gunk]

Hey Folks Thanks for all the advice. Michael Morse has helped Me with the entire eng. package,Can't say enough good things about Him.Great guy to deal with and He is generous with His Knowledge and years of experience building and tuning. Ordered My VM 34's thru Him, torque peak optimizers,All the info I need on putting together a decent, reliable bike. Oh . In regards to why don't I get a Hayabusa,
Is I'm too damned old and I 'd be dead by the time I grabbed top gear!And building up a bike is at least 1/2 the good therapy of biking .That's My take on It. Especially when You have 5 or 6 months of winter up here.
Thanks again.

 

[hooser]

Take a look at the 2 dynos, they show less hp with the cones and less torque. One was with a 700 and the other a 750. Both had, Shell #1, 34mm vms and 1 3/4" od 1 5/8" id tt pipes. I can't find the 700 torque but It did not work for my setup ether. I would be interested in seeing your dyno after the set up with the torque optimizers. I am always looking for better performance. Gary

 

[Tomterrific]

Hi Gary,

I believe what Michael is trying to achieve with the anti reversion cones and reducing the diameter of 1 3/4" exhaust is engine smoothness/driveability at lower rpm.

Tom

 

[650performance]

Willy, I wouldn't recommend ever boring the stock liners out to any more than 700. The sleeve walls become too thin and the walls begin to distort when you couple the high cylinder pressures of a "built" engine with WFO 6500+ rpm. The result is that the rings don't seal as designed and power is lost. I have talked with racers who have tried to go beyond 700ccand they report that on post race teardowns they can see evidence of uneven ring wear and sealing issues. You want to retain AT LEAST 2mm sleeve wall thickness, and more is better. When in doubt, resleeve for high performance overbores.

 

[hooser]

I agree no more then 700 we do a lot of them and Shell before me and they work and hold up great.
On another note I found my torque cone torque test. 1 shows less torque and the other shows that the cone move it about 500 rpms down with .26 less pounds of torque.. I like picture HaHA!

 

[hooser]

I finally found Rogers 70hp dyno runs, his mile motor.

 

[pennswoodsed]

I finally found Rogers 70hp dyno runs, his mile motor.

I guess for the mile , the torque hole at 4000 +- rpm didn't matter ?!
Thanks,Ed

 

[Signal]

Has anyone used exhaust port optimisers (that insert into the head) in conjunction with the Lillie replica head in a race engine?
Or are the characteristics of the port changed so that they are not needed or even detrimental.

 

[650performance]

Yes, I have used the exhaust port inserts sold by Michael Morse in my race engines fitted with Lillie heads for over ten years. They help produce a very smooth power curve, which is noticeable in some throttle roll on situations, and do not detract from maximum power, which in my engines vary between 69 - 73 RWHP as measured on a DynoJet 250.

A caveat is that I have never used them in flat track configuration, only in road racing.

I did not obtain any measurable benefits with the other style inserts placed at the end of the header pipes at the point where the megaphone is clamped on. They did appear to cut down the power at max rpms by a very small amount and did not appear to help or hinder the shape of the power curve. Perhaps in another engine spec they would provide a benefit.

 

[gunk]

Thanks for all the advice guys. Here's what I wound up with.
Neider 750 bigbore cyl. kit. complete finned cyl. assy, not sleeves,portred head,
34mm mik VM's from Michael morris jetted perfectly I might add.the anti reversion cones in the head pipes at the ex. ports tried the torque cones in the pipes and then tried without. Deciced to leave them out. the Neider cam specs are the old Webco cam specs according to Mike Morris, Man that guy is a walking encyclopedia of info!A set of Ascot pipes with the extra muffler packing that got Me thru a sound test(sweeet) Dropped 3 teeth off the rear speocket and She'll still leave a set of lights in 2nd gear. Nice smooth torque curve on My seat of the pants dyno. I have to give a big thanks to Michael Morris
for all the Net and phone advice, plus I had the throttle cable snap inside the junction box
on ride #1 called Michael to order another(these things happen no one's fault) and He
warrantied the cable and mailed Me another one pronto to Canada FREE OF CHARGE not even postage. Noe THAT is A+ customer service!No Idea of H.P. or torque figures but
she pulls a lot stronger than the stocker and that's what I was after