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Trex
XS650 Addict
I'd like to see a step by step and a parts needed list. I'd love to get the most out of my engine after all the work I put into customizing my XS. Planning a 750 kit next year and would like to do this 277 rephase at the same time.
- yes a 277° rephase is done by rotating the rhs on the original splined shaft, the cam needs to be cut and one side rotated the same...a 270° rephase needs an offset splined shaft and the cam changed...both require new ignitions...shafts should be welded for security
yamaman
xs650 addict
- Messages
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Just to add, a 277* can be done with the existing crank. To build a 270* motor (considered the better of the 2) you need the halves of 2 crankshafts & a specialy machined shaft.
For all it's worth, the 277* is most likely near enough. It will only cost you as much as a crank rebuild, a new cam & a new ignition. The 270* will cost you that + a second crank & the new shaft.
For all it's worth, the 277* is most likely near enough. It will only cost you as much as a crank rebuild, a new cam & a new ignition. The 270* will cost you that + a second crank & the new shaft.
Some great info here, thanks guys, a Q though - Do you weld both sides of the pin? Is it possible to pull down the crank again after to replace the conrods?
Only way I can think of doing it would be grinding, cutting or drilling the pin out, useing a welder to build the flywheel back up, then machine it back to spec and useing new pins...?
Only way I can think of doing it would be grinding, cutting or drilling the pin out, useing a welder to build the flywheel back up, then machine it back to spec and useing new pins...?
pyrocentric
XS650 Addict
- Messages
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Can you guys clear something up for me? What exactly is the firing order.
In the animated gif image on page one, is it:
Fire Black Piston at top, exhaust orange piston at top, exhaust black piston at top, fire orange piston
or is it
fire black, fire orange, exhaust black, exhaust orange
In the animated gif image on page one, is it:
Fire Black Piston at top, exhaust orange piston at top, exhaust black piston at top, fire orange piston
or is it
fire black, fire orange, exhaust black, exhaust orange
Sundie
Jabroni
it depends on what your cam/ignition is set up to do.
pyrocentric
XS650 Addict
- Messages
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By my reasoning there would be no reason to go with the successive power strokes and long pause unless you just wanted it to sound like a harley.
Sundie
Jabroni
No matter what you do, it's going to be uneven by 83/90 degrees, for 277/270 phasing respectively. But i agree, the first power stroke should be pulling the other piston in for the intake stroke for best balance.
Rev D
XS650 Enthusiast
Hmm, a little interesting light reading to round out my night.
I`m going to be dismantleing the engine I have in my XS, as it is newly mine and looks to have been thoroughly neglected, and I`m making a list of what I might do while it`s apart.
The 277 seems like a cool idea, and I get the part about rotating the crank. but there was also mention of a new cam?
Where would one price out said cam?
(oh and my charging system is shot so setting up a perm magnet set up and it seems the new ignition is pretty cheap too so I'm looking to do that anyways, so the intternals of the engine would be my real only new cost)
I`m going to be dismantleing the engine I have in my XS, as it is newly mine and looks to have been thoroughly neglected, and I`m making a list of what I might do while it`s apart.
The 277 seems like a cool idea, and I get the part about rotating the crank. but there was also mention of a new cam?
Where would one price out said cam?
(oh and my charging system is shot so setting up a perm magnet set up and it seems the new ignition is pretty cheap too so I'm looking to do that anyways, so the intternals of the engine would be my real only new cost)
cooltouch
XS650 Addict
I'm in the middle of a rephase project with my '78 XS650. Been "in the middle of it" for several years, unfortunately. Health problems have gotten in the way, but hopefully I'm working through the worst of them, and now all that stands in the way of completing the project is finding the time and the money.
I was attracted to a 277* rephase for a few reasons. First, I just really like the sound of 270* twins like Ducatis and Moto Guzzis. And of course I found the fact that the motor will vibrate a lot less quite appealing. Plus, my project will have a 750cc kit, and I'm thinking that, as a 360* twin it might vibrate even more than a 650cc, so all the more reason to rephase the motor.
I had Webcam (http://www.webcamshafts.com/) regrind my stock cam to their 59A regrind, and had them grind it for a 277* motor. It is my understanding that Megacycle will do this also. If I had it to do over again, I'd probably go with Megacycle because I think their cams have better performance characteristics than Webcam's. I've asked Mikesxs a couple of times if/when they'll be doing a 277 cam, and all Mike said was that it's under consideration. That was a while back, though.
I printed out pics and explanations that were located at Bertaut's website on how to modify the crank, and took these along with the crank to a friend of mine who is a machinist and who specializes in machine work on motorcycles. The mods were easy enough for him to do. I haven't welded up the crank pins, though -- yet. I too wonder why this is strictly necessary and also how one will separate the crank in the future to replace bearings or rods.
I corresponded with Pamco Pete back when he was first developing his ignition system and he told me that setting it up for rephase was do-able and that all I had to do was request one for 277* (for a minimal upcharge as I recall). Hopefully he still offers this, because his ignition system is the one I was planning on using. Can't modify a Boyer cuz it fires a waste spark and that won't work with a 277* motor. Some folks have modified their points plate for 277* but I have no interest in running points and will consider that option only as a final and last resort.
Right now, I'm backed up with other projects, and I don't know when I'll be getting back to my '78. I have most of the parts for it now, just need to finish doing a bit more tearing down and then I can get started on assembly. I'll let y'all know when this begins.
I was attracted to a 277* rephase for a few reasons. First, I just really like the sound of 270* twins like Ducatis and Moto Guzzis. And of course I found the fact that the motor will vibrate a lot less quite appealing. Plus, my project will have a 750cc kit, and I'm thinking that, as a 360* twin it might vibrate even more than a 650cc, so all the more reason to rephase the motor.
I had Webcam (http://www.webcamshafts.com/) regrind my stock cam to their 59A regrind, and had them grind it for a 277* motor. It is my understanding that Megacycle will do this also. If I had it to do over again, I'd probably go with Megacycle because I think their cams have better performance characteristics than Webcam's. I've asked Mikesxs a couple of times if/when they'll be doing a 277 cam, and all Mike said was that it's under consideration. That was a while back, though.
I printed out pics and explanations that were located at Bertaut's website on how to modify the crank, and took these along with the crank to a friend of mine who is a machinist and who specializes in machine work on motorcycles. The mods were easy enough for him to do. I haven't welded up the crank pins, though -- yet. I too wonder why this is strictly necessary and also how one will separate the crank in the future to replace bearings or rods.
I corresponded with Pamco Pete back when he was first developing his ignition system and he told me that setting it up for rephase was do-able and that all I had to do was request one for 277* (for a minimal upcharge as I recall). Hopefully he still offers this, because his ignition system is the one I was planning on using. Can't modify a Boyer cuz it fires a waste spark and that won't work with a 277* motor. Some folks have modified their points plate for 277* but I have no interest in running points and will consider that option only as a final and last resort.
Right now, I'm backed up with other projects, and I don't know when I'll be getting back to my '78. I have most of the parts for it now, just need to finish doing a bit more tearing down and then I can get started on assembly. I'll let y'all know when this begins.
BigJimmyW13
XS650 Guru
Ok so apparently I need to get with you in The winter to do the 750kit and rephasing!! 
cooltouch
XS650 Addict
Ok so apparently I need to get with you in The winter to do the 750kit and rephasing!!
Sure. Up there at CS or down here?
Maybe this will motivate me to clear some other stuff out of the way and finish up my project.
BigJimmyW13
XS650 Guru
Probably there since I don't have a garage here yet. I built my bobber/chopper in my kitchen. However, I'm looking for a new house here in CS to rent and I'm keeping my eyes open for a house with a garage and a bigger back yard - I have a pair of 180lb dogs.
cooltouch
XS650 Addict
Welp, my garage is full of bikes and other stuff, but I have a carport, at least, which is where I do most all of my work. For smaller detailed stuff, I have a small shop behind my garage that I use.
BigJimmyW13
XS650 Guru
How many bikes/what bikes do you have?
cooltouch
XS650 Addict
1981 XS650 Special
1980 XS650 Special
1978 XS650 Standard
1977 XS650 Standard
1988 BMW R100RS
1976 BMW R90/6
1974 Norton Commando 850
1987 Sportster hardtail bobber
1980 XS650 Special
1978 XS650 Standard
1977 XS650 Standard
1988 BMW R100RS
1976 BMW R90/6
1974 Norton Commando 850
1987 Sportster hardtail bobber
I went for a ride on my mates 277 Rephased 650 with 750 kitt (Mkes), and a cam made here in OZ, (secret grind ) Stainless valves (Mikes), dremeld the ports. Oil Cooler (mikes) VM 34's 
The thing is not an XS any more, does not sound like one dose not respond the same,
only got it into an 80k area and got it out to 100K's, when i turned it around and give it some stick up to a 100k's second was up to 80k's in no time and 4,000 revs and was just asking to be let loose 
.
Be good for a side car
Well John an 8.1 is a good cheep way to take out the vibes and prolong the life but if this bike was ridden with a blow out now and then, as all motors should have done to them, this set up will thrill and last. And no vibes on the short run.
What are you going to do with that money when your dead any way,
I'm convinced so when a crank has to come apart it gets a 277 and i won't have to loose all those unnecessary parts for less weight
The thing is not an XS any more, does not sound like one dose not respond the same,
only got it into an 80k area and got it out to 100K's, when i turned it around and give it some stick up to a 100k's second was up to 80k's in no time and 4,000 revs and was just asking to be let loose . Be good for a side car
Well John an 8.1 is a good cheep way to take out the vibes and prolong the life but if this bike was ridden with a blow out now and then, as all motors should have done to them, this set up will thrill and last. And no vibes on the short run.
What are you going to do with that money when your dead any way, I'm convinced so when a crank has to come apart it gets a 277 and i won't have to loose all those unnecessary parts for less weight
