Rephasing, What is it?

Well I am no scientist or physics major, alas just a tool maker who programs robots for a living. My son got me interested in the xs 650 craze and I have ridden both the stock and the rephase. I do all the work on the rephase (not as technical as some) and I can honestly say the rephase is my preference. I am now in the process of a second rephase with the third right around the corner. I rode the second quite a bit before taking the motor apart and I will be paying some pretty close attention to the power after it is done. I will reply with some back yard findings.
 
dps650rider said:
So, from what you are saying there is no advantage to offsetting the crank pins on an inline twin? Then why did Honda make so many twins with 180 degree cranks? To change the sound? With the pistons in different planes the cancellation is incomplete but the reduction in vibration is still significant.
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There is no advantage as far as bearing loads are concerned. Even adding counter-balance shafts doesn't reduce the crank bearing loads. They only add a second mechanical imbalance that pushes the opposite direction as the crank so the rider doesn't feel the crank vibes.

Changing the crank phase certainly does change the sound and feel of the engine. A 270° crank will have a lower vibrational amplitude than a 360° crank, and a 180° even lower still. But a lower amplitude doesn't necessarily mean that it will feel better. When you listen to music, do you decide whether you like a song based solely on the volume it was played? I've crunched all the numbers and can scientifically prove that a re-phased engine will transmit vibration to the rider at a lower amplitude. But, even knowing all that, I don't like the way a 277° feels compared to a 360° crank.

In my opinion, the only reason to re-phase an engine is if you like the sound and/or feel of it better than what you currently have. Arguing about which crank configuration is "best" is like arguing about which beer is best. Everyone's tastes are different.
 
mrriggs said:
In my opinion, the only reason to re-phase an engine is if you like the sound and/or feel of it better than what you currently have. Arguing about which crank configuration is "best" is like arguing about which beer is best. Everyone's tastes are different.
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My opinion is a bit different. I like the sound and feel of a 360 (rode mine like that for many years and miles), I'm not crazy about the sound and feel of a 180, I like the sound and feel of my 277, and a true 90 V twin is sweet.

The other thing comes into play here is the frame, seat handlebars, etc. I have the factory replacement king and queen seat/sissy bar on mine and with the 360 my wife complained about the vibration of the backrest when she rode on the back. I would also get quite a bit of vibration that was bothersome at my lower back where the step in the seat contacted it but I found that I quickly got used to it in the spring when riding season started.

With the 277 the vibration at these points is diminished to the point where my wife never complains about it even if I ask, and I never get the tingling in my lower back at the beginning of the season. So for me the 360 and 277 are very different in feel and I like them both, but the deciding factor in favor of the 277 is the vibration reduction.

Still, I wouldn't mind having a second one that was stock just for fun. :bike:
 
I wouldn't get to caught up this bearing loading when rephasing, the Aussies have built some radical XS's over bored and stroked out rephased engines that have been severely pushed to their limits and have been to Hughshanddbuilt shop on several occasions and not once have I heard Hugh(and Hugh isn't a one for pussy throttling either) or the Aussies mention a crank bearing failures. The only bearing failure I've ever seen came from a standard XS.You simply can't have your cake and eat it too when it come's to engine alterations.
 
There are so many pluses and minuses on both. Me I like the stock bike with the vibration and I am not looking for the bike to due nothing but what it was made to do. I have had only a couple motors in shop rephrased and like I told the guys who owned them I don't carry spares and if the cam or crank or ignition have a problem I am going to have to order new or send back the bad part. Now I always carried stock spares and those were used right away to get the bike back on the road. Me I am not looking to go fast or change the sound just like to get on the bike and ride it around town. If I want speed I jump on the BUSA or if I want to cruise long distance I jump on the HARLEY.
Again I just like the ride and feel of the xs650 in a hard tail frame and have fun.
So I am in the middle if you want to do it go for it if not just enjoy the ride.:thumbsup:
 
wildav said:
it does sound good !
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If you want to capture the Duke sound,it's not gonna happen with obnoxious sounding straight pipes. You need to dampen the high's with some type of inner packing. The best type of muffler would be the old "Bub's" off a Guzzie or a more modern kick ass muffler by Staintune like in this vid.The Bub's will exhibit a more bark with deeper growl that the Staintunes. Add a Web cam 59A for that off idle lope.

 
My 270 degree Rephased XS650 with big bore kit is finally running! I really love the SOUND!!!!
Just thought you all might like to hear it with these old school fishtail exhausts.
 
270 uses the same crank.......split the crank..........twist the crank so as to turn 3 splines and reassemble...........

270 needs another crank so that the same sides are used and a special shaft with splines, both ends, rotated so the crank when assembled will be 270......the spline is inserted in the two female crank half's

read through this link..........Bit to read through but there is extensive info on a 270 rephase with pics
http://www.xs650.org.au/Club Racer Stuff/Club Racer.htm
 
Fascinating read..I think i undrestand a little clearer on what rephasing is. From my point of view..we wont be rephasing the motor.. I'm in the camp that a proper tune will be sufficient for my needs.
 
650Skull said:
270 uses the same crank.......split the crank..........twist the crank so as to turn 3 splines and reassemble...........

270 needs another crank so that the same sides are used and a special shaft with splines, both ends, rotated so the crank when assembled will be 270......the spline is inserted in the two female crank half's

read through this link..........Bit to read through but there is extensive info on a 270 rephase with pics
http://www.xs650.org.au/Club Racer Stuff/Club Racer.htm
Click to expand...
Witch on do I need 2 read
 
Skull only has 1 link there to read. The top line should say 277 not 270.

IMO unless you really want a v-twin like sound, or you can do all the work yourself, I wouldn't bother. I rephased mine, crank and cam myself. I like the sound, but I don't think I would bother again.
 
Cafe Murdock said:
Witch on do I need 2 read
Click to expand...

I can't exactly recall what year the crank info is in.........i think it is in a couple of years...........

Now i could go back through, find out, and post the exact year and placement on the page, (eg, scroll down half way or to the bottom), but i thought, all it really takes is to click on a year and a quick scroll will reveal some pics and read from there.............

if that is to much just ask again and i will do all the work for you...................then again maybe not................
 
solo2racr said:
Says the youngster who would be LOST without his "smart" phone.

Point is, if you want some of us "old guys" who were wrenching on XS650s when they were new to bother reading your posts, you MAY want to rethink that.
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Fair enough but half of it's where I'm from that's how people talk n the other half is the damn phone with auto correct n I didn't grow up with a phone n my hand I grew up working n and learning in my family's auto and fab shop learning all I could I'm right there with u about phone's n computers n I like things the old fashioned way cuz that's how I was raised
 
650Skull said:
I can't exactly recall what year the crank info is in.........i think it is in a couple of years...........

Now i could go back through, find out, and post the exact year and placement on the page, (eg, scroll down half way or to the bottom), but i thought, all it really takes is to click on a year and a quick scroll will reveal some pics and read from there.............

if that is to much just ask again and i will do all the work for you...................then again maybe not................
Click to expand...
Right lol I hear that I'll check it out again I emailed hhb for a cost break down and more info I'm really just lookin for info for a cost vs. worth it pros and cons kinda break down to be able to make a informed decision I mean ive got all the parts n stuff I believe for one n I've got 3 spare complete motors for part alone I just would lik sum info n number to b able to evaluate and move forward thanks again
 
650Skull said:
270 uses the same crank.......split the crank..........twist the crank so as to turn 3 splines and reassemble...........

270 needs another crank so that the same sides are used and a special shaft with splines, both ends, rotated so the crank when assembled will be 270......the spline is inserted in the two female crank half's

read through this link..........Bit to read through but there is extensive info on a 270 rephase with pics
http://www.xs650.org.au/Club Racer Stuff/Club Racer.htm
Click to expand...
I checked it out again. N it won't let me click on any or the years
 

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