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Rephasing, What is it?

Discussion in 'The Garage' started by plane_ben, Oct 25, 2009.

  1. plane_ben

    plane_ben XS650 Junkie

    Plane_ben Wrote:

    I got my answer. The way I have it now would be a 305 rephase. According to mriggs, he could rephase my cam the same way and make it sound like a S&S X-Wedge motor.:D But I'm sticking with the 277 rephase.
  2. imworks

    imworks XS650 Member

    Last edited: Apr 11, 2013
  3. crossfire

    crossfire mennonite scum

    what front rim did you lace to that hub?
  4. joebgd

    joebgd XS650 Addict

    The thing is not an XS any more, does not sound like one dose not respond the same,:umm: 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 :D.

    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[/QUOTE]

    What does this mean 80k etc. Is it rpm distance the pargraph is confusing my us track mind ibthink. Lol

    Posted via Mobile
    Last edited: Aug 6, 2014
  5. cooltouch

    cooltouch XS650 Addict

    I think he's referring to kph -- kilometers per hour. Kind of an odd way to make the reference, though.
  6. dang! is rephasing my 1971 xs b1 not gonna be as simple as i thought?
  7. 650Skull

    650Skull Dinosaur Lives Top Contributor

    Don't know. How simple did you think it was going to be????


    1 Completely tear down the motor
    2 Disassemble the crank
    3 Replace any worn parts
    4 Re-assemble crank in the right configuration
    5 Get or have the cam re-phased
    6 Rebuild Crank and motor
    7 Ignition system for a re-phased crank.

    Simple. Its the cost that is not so simple.

    Slight loss of torque but transferred to power and now we are finding, most that were itching to do and have done this would not do it again.

    Vibration is minimized but still there and it has been known to still make the hands numb after a couple of hours riding.

    States in the article.

    "If you elect to not go with the slotted sprocket, the cam needs to be degreed by pressing the sprocket on and off the camshaft. Not a good plan at all."

    Not so, it has been done and is being done all the time without any problems. Note. need to be precise in marking and realigning.

    I think re balancing is important when doing this or if the crank has to come apart. It is a simple case of drilling holes where the weight has to come out.

    In this article scroll down to 14-10-2014, (we have day/month/year In Australia), and see how the weight was removed from the crank to balance it.

    Don't freak out this whole article is about building a re-phased Club racer so a lot of extra work done to achieve a competitive bike.
    Last edited: Feb 20, 2015
  8. wannabridin

    wannabridin XS650 Junkie

    I decided not to rephase. 1st matter was cost, it went outside my "budget build" mentality. (granted, my budget is nowhere nearly as cheap as others, but it's lower than i want). For Hugh to do the work, you're looking at $300 for the crank, another $185 for the cam and shipping both ways (about $100 or so).

    2nd was powerband. Talking in depth with Limey Bikes, he doesn't like re-phasing either because of the torque curve shift. A big reason people like these twins is their low RPM grunt, which makes for easy riding in town. For most of the cost of the rephase, you could have your crank sent to Falicon and dynamically balance it which would REALLY help with vibes, but is mostly unnecessary on relatively low-revving street bikes.

    I like the original character of these bikes. The rephase sound is a bit better to my ears, but nowhere near enough to justify it. I'll just work on balancing my carbs as best as possible and adding some extra mass to tune the handlebar frequency and deal with the vibes from there.

    I'm not knocking Hugh, he provides a great service to those that want it, it's just not for me.
  9. Does anyone know if Yamaha's factory team flat-track motors in the Championship era were stock or other crank spacing? I know they played with pretty much all configuarations, but what cranks were they winning with?

    I've been out of XS650's for a year or two (FJ1200's now being the objects of my life-long motorcycle love affair). But I'm thinking of adding one to the stable.

    I'm thinking "fire road" style (wide bars,trials universal tires, high pipes/supertrapps). Rear wheel control is a biggie with that kinda bike.

    Anyway, I was thinking about changing the crank throws and pretty much decided not to.

    I'm wondering if all this crank-pin mod stuff is just a phase that the XS650 community is going through. Like (I hope) the Bobber thing.
  10. I love the 360 crankshaft. The low end grunt. The sound. I'd never rephrase. If I wanted something that could Rev there are plenty of kz650 kaws out there.
  11. lol sorry 650 skull my main concern was weather i could use my stock crank.if i read correctly some early 70s models in previous posts seemed to be more complicated .please correct me if I'm wrong, i appreciate what a great resource it is to have u guys here to help me on my first rephase.
  12. 650Skull

    650Skull Dinosaur Lives Top Contributor

    No difference between an earlier or later crank. The difference between 256, (70-73) rods and later 447 rods is the little end size. little ends on earlier rods have been known to stretch and brake when run hard so if your re-phasing to rev past 7500 then changing to 447 rods would be a better move. ...........more cost.

    Here is the link to the motor i refereed to in my last post. The crank is off an XS2, i think, but they were using an XS1 crank first before they found some damage before assembly
    Last edited: Feb 21, 2015
  13. the rods were longer, the pistons carried the small end further up and on needle bearings. Also, the early cranks had lead throw weights which sometimes came unglued.
  14. huh? the "energy" is produced by the force exerted on the piston tops by expanding gas in the combustion chamber; it does not change when you alter the relative positions of the pistons. re-phasing redistributes the power pulses it does not make more power.
  15. Burns, the premier flat track XS engines built in the '70s did not feature rephasing. All manner of crank variations were experimented with, but none provided a sufficient benefit. In talking with Bud Aksland, who built KR's engines, none of them were rephased. Ditto with Harry Lillie, Axtell and other high end builders and tuners. This is true with both the stock-based engines as well as the later race-centric OU engines.
  16. That's what I thought 650P. Thanks for the authoritative answer.
  17. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    Seems to me that this rephase fad is all about separating naive bikers from their money.
    Clever marketing hype by the sellers, suggesting more horsepower and/or more torque, is a sure way to increase profit. The male ego knows no bounds.

    If the buyer of the rephase is happy with the Ducati/H-D exhaust sound, that's all that counts.....................its a win/win situation. :bike:
  18. 650Skull

    650Skull Dinosaur Lives Top Contributor

    650P, there was all that development done to the head that was/still lost to a generation. The re-phasing would help to make the XS650 a more competitive race bike with the extra revs for top end speed
  19. I believe you can buy a copy of the OW head from MMM at 650 Central (http://www.650central.com/); and there's a fella calls himself "jack" - who I think chimes in here from time to time - who know all there is to know about the xs650 cylinder head. So that knowledge ain't lost.

    As to rephasing making the XS a more competitive racer, well MMM would know all about that so ask him when you find $1700 for that head - but competitive at what? It's doing just fine in vintage racing and will never run with modern stuff no matter what you do to it.

    I think re-phasing's advantage is strictly vibration reduction.
  20. 650Skull

    650Skull Dinosaur Lives Top Contributor

    Yes it is.

    Jack has spent hours and hours rebuilding ports and reshaping them himself to acheave the results he has. I don't think his work was a copy of the early race info.

    And there was a head especially cast for the XS and that knowledge is lost.

    Yes, its doing fine in vintage racing and you will find just about all the successful ones are 270 re-phased.

    The vibration reduction on the 277 re-phase is reduced but it is still there in a, how shall i put it, higher or more intense vib. Doesn't show in the mirrors but is still prevalent through the handlebars. Referred to in post #128.

    I think the cost per vibe reduction is, (as RG says), a lack of knowledge about the xs650 motor. The in crowd have no idea how the pressed on crank really works, the real weight of the tonnage required for the assembly before it needs new pins or a welded crank.............. "Plenty of cranks out there so all XS650 cranks should be welded"............... comments like that dose nothing for real time information about these cranks. The thing is even 750 kitted cranks do not have to be welded, sure in certain instances or riding habits, it is recommended, that also goes for the standard 650 engine................. But not a given.

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