Rephasing, What is it?

Punkskalar said:
Jack,

I fully respect you, but I have to disagree. I don't have numbers or Dyno figures to back it up, and admit that. But Nobody has ridden around a rephased engine and thought it had the same power of a stock engine that I know of. And, to try and prove the Rephase builds more power, I am building a bone stock engine internally, all stock pistons, cam, etc... just rephased and will be testing it in a known chassis. :thumbsup: Hopefully that will happen this spring. I will find someone willing to dyno their bike, and GIVE THEM A FREE REPHASED ENGINE if they will do a before and after dyno test... :D

If I am proven wrong, I'll be happy to admit it. But the rephases just keep proving to be a powerful engine with excellent throttle response and torque. Even a 750 Kitted XS isn't comparable to a rephased engine, in my personal experience.
Click to expand...
Good Luck in your dyno testing! It's all about changing the reciprocating masses at their maximum velocity points in assisting the opposing mass through it's cycle. Sorta like a see-saw balance effect,which in effect lowers the stress loads on the bottom end, vibration, allows much higher than normal RPMs and quicker engine response. Go to Britbike.com for some thorough discussions on this exact topic.
 
hi guys yes,,, for a rephased motor try looking up probe-eng.com,, as a couple of guys in australia have rephased probe electronics on their bikes.... and the standard of build is very high with well thought out electronics.. and easy installation ,,he,s also been on the racing side as well ..regards oldbiker
 
Punkskalar said:
Jack,

I fully respect you, but I have to disagree. I don't have numbers or Dyno figures to back it up, and admit that. But Nobody has ridden around a rephased engine and thought it had the same power of a stock engine that I know of. And, to try and prove the Rephase builds more power, I am building a bone stock engine internally, all stock pistons, cam, etc... just rephased and will be testing it in a known chassis. :thumbsup: Hopefully that will happen this spring. I will find someone willing to dyno their bike, and GIVE THEM A FREE REPHASED ENGINE if they will do a before and after dyno test... :D

If I am proven wrong, I'll be happy to admit it. But the rephases just keep proving to be a powerful engine with excellent throttle response and torque. Even a 750 Kitted XS isn't comparable to a rephased engine, in my personal experience.
Click to expand...

Actually, I think you're both right. The engine doesn't produce more power: thermodynamically, it can't. BUT, more power gets to road because you're not pumping that energy into the vibration of the bike. So, the engine isn't more powerful in a thermodynamic sense, but since you've just improved the mechanical efficiency, you do get a lot more out.
 
New to site and wow!!! Just about to get my old girl out of the shed and start her restoration which should be not too terrible.
 
rephasing... is going from 360degree,,,, to 270 or 277 ... ..i,ve ridden a xs650,, with a rephased crank... and all he did was seperate the crank and move it 3 splines and put it all back together ... i took it for a spin around ORBOST in aust... and it sounded like i had a ducati up my bum,,, it sounded real nice and the extra torgue was great,,, i was listerning so much that when i went around the corner i nearly dropped it ,,, but i didn,t tell the guy that ... but if i had a spare motor i would rephase it ... regards oldbiker
 
The phasing makes the XS650 motor similar to that of a V-twin but mine sounds more like a Ducati than a typical V-twin like a Virago.

I.
 
Rephasing,transforms the engine,not sure how much more power it makes but tourqe seems to be the the big winner,mine is a 277,750 kit,rephased mild street cam,ports cleaned up,vm 34 carbs,was running points but just fitted pamco with std.coils,std headers open mufflers,it still viabrates but not as much,another pluss is the statrer works much better,if you can afford it do it.
 
I seem to remember reading that Edward Turner suggested the 270 phasing to Triumph shortly after he became their chief designer. Triumph turned the idea down because there (supposedly) was no suitable ignition available. Anyone have more information on this? Back in the 80's I saw a copy of a Australian engineering report with details on 270 degree phasing for parallel twins.
 
Triumph's new 1600 and 1700 cc twins are 270 rephases, I guess they figured out how to get an ignition to work.
Leo
 
Are there non-high performance cams available? I'm dreaming of a rephase, but I'd like some of the longlivity retained.
 
you generally get your cam cut/welded at the same time you get your crank split/moved/welded. I've heard $500 bandied about as a cost for this, given you ship your crank/cam in a box. (ie: out of the engine)
 
I'm really doubting that you get any extra torque out of it. But, i *will* accede that it *feels* like more, because you're revving higher without having your hands vibrate off. :D
 
As far as the clutch not holding up, there might be an option worth looking into. We built a megahorspower Hayabusa with dual turbos and 3 stages of nitrous. We couldn't get through the first stage without smoking a clutch. I don't remember exactly what it was called but it fingers the came out centrifugaly to hold the clutch tighter. It worked so well that we smoked the clutch on the dyno and didn't even know until the our numbers started dropping! I want to say they called it some kind of spider clutch setup or something.

Has anyone else ever dealt with this setup? Is it possible that something like this could be incorporated into the XS to help save the clutch from "hot rodding" the engine???
 

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