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how to porting and polishing

Discussion in 'The Garage' started by tommerr, Jan 13, 2012.

  1. tommerr

    tommerr XS650 Member

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    I would like to see a thread about porting and polishing with lots of pictures for this old fart (my first bike was purchased in 1965). About ten years ago, I discovered the XS650 and I bought a bunch of everything including ten extra engines. I am only now getting around to building the bike of my dreams. I re-phased a flywheel assembly to 270 degrees some years ago and this winter I want to progress. May I have some of your thoughts on porting and polishing?
     
  2. Highside

    Highside Lord of the Flies

    Get a junk cylinder head and a 1/4 die grinder with a 6" extension. There's a brand called All Pro (IIRC, don't quote me) that's about $50, that's the cheapest 6" extension die grinder you'll find. You're going to need an egg shaped 3/8" bit that's mean for aluminum. You can use the ones for steel too, but you need to use a lot of WD-40 to keep the aluminum from clogging up the bit. Next you'll need a cartridge roll mandrel and about a dozen cartridge rolls.
    One you have all your equipment, talk to someone who's done this to have them tell you where to grind, and far more importantly, where NOT to grind. It's always easier to remove metal than put it back. :wink2:
    All in all, porting isn't that hard if you have some basic hand skils, you just neet a bit of practice before you do it on something you want to run.
     
  3. tommerr

    tommerr XS650 Member

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    I have the mechanical skills. I have been machining for forty years. This bike will see my every effort. I request direction on what to do and what NOT to do. Years ago, I polished the H*** out of a set of heads and I do believe that I scraped them out. That is what happens when you work in the dark. This web site is so full of meaty information. I owe a thank you to many for sharing their expertize.

    All the Best

    Tom
     
  4. Jack

    Jack XS650 Junkie

    What's your engine combination gonna be? Can you get the heads bead blasted,then post pictures of the intake & exhaust bowl pockets and a shot of exhaust port exit(close up of the inner lip.The intakes,depending on how the ports where cast can yield positive gains of 15% flow gain on intakes and around 23% for the exhaust but for the most part a flow ratio of 70 to 75% is within reach of the DIY porting and depending on cam selection 70% ratio would be the ideal goal. The exhaust ports can double it's flow to a point of out flowing the intake Flow100% but that takes thought out planning in reference to cam choice,etc:)
    The sky's the limit when it comes to porting and modifying the intake ports,really depends on engine combination and it's intended usage or how you want the power delivered.
     
  5. Highside

    Highside Lord of the Flies

    I just remebered the brand of die grinder, it's called PitPro. $35 plus shipping

    http://www.huronindustrial.com/mm5/...=1-832-PT2440&Category_Code=10&Store_Code=his

    It's kinda hard to describe online where to grind, but as a rule, you never grind the port floors or the long turn radius, just past the valve guide. You can blend in that area past the valve guide, just try not to make it any bigger.
    Mostly, you're just trying to blend the mis-match between the machine work and the casting. If you have more than one cylinder head to choose from, then pick the one that shows the least amount of core shift.
    Also you want to smooth out the short turn radius on both the intake and exhaust ports. Again, don't get too crazy removing material. The ports on the 650 head tend to be a bit big as it is, and the exhaust port is especially too big. only clean up the areas that need it. :cool:
     
  6. Jack

    Jack XS650 Junkie

     
  7. Highside

    Highside Lord of the Flies

    Jack,

    I ran the cylinder head department for more than one professional NHRA team, with national championships under their belt.

    You do the math. :thumbsup:
     
  8. I did a light porting/polishing on my 72' head. Just by looking at it you can see the imperfections on both the intake and exhaust side. I doesn't take much effort to get the ports to were you want them.

    Its very easy to see the bumps, ridges, and restrictions on the head. Remove the material first with burr type tools, then sand paper drums to smooth it out. It has been covered before but exhaust ports can be polished smooth, but intake ports do not polish smooth leave them a little rough for the atomization.
     
  9. Jack

    Jack XS650 Junkie

    Highside, I always get a good laugh when you talk of all your professional experiences doing this and doing that but yet I see you post questions regarding getting information on porting the XS head as so not to screw it up.Guys like you,doesn't matter what type of forum it is who think they know it all just come and go strutting their feathers blowing a lot of hot air.
    So why don't you just take the time to enlighten some of us with what experiences you have with porting the xs head and how would you maximize the intakes port efficiency by biasing the flow from 100,200 to 300 to 480 lift or how to minimize turbulence in the exhaust port turns without creating resistance that inhibits flow.
    I have friends with higher credentials than you in the racing field who also throw around the experience game BS for argumentative purposes.:laugh:
     
  10. tommerr

    tommerr XS650 Member

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    What I am building will be a 1930's Indian Scout type bike but with my beloved XS650 engine. It will have a side car with a jet drop tank sidecar body. Yup, I drove from Illinois to Pa. to pick up two NOS 1952 drop tanks. This will not be a racer yet I want my this to be the very best. I am going 750 with a permanent magnet generating system and a decompression starter. I figure it this way. When I'm too old to ride solo, I can still ride a sidecar. I remember a long ago post from a sidecar guy who rode a solo; "When I stopped, I forgot to put my feet out and the bike fell over."

    I respectively request help from the many experts here to guide my poor efforts. I have a hard tail from TC. I am talking to KIWI Indian about custom forks. My direction is entirely antique. I want my bike to look like it came out of a time warp. That is Tom. By the way, I work in an aerospace materials laboratory. I work with many many top drawer engineers. They love to field technical questions from A to Z.
    The more I read about engine stuff, since my engine is a part, the porting and polishing sounded like a very good thing. I will post many pictures. Winter is here and my shop is cold. Thus, I buy parts and research.

    All the Best

    Tom
     
  11. 5twins

    5twins XS650 Guru

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    I just use a Dremel to do mine. I use a couple different size ball cutters, the sanding rolls, and the "Midi" or Kratex wheels and points. These are rubber impregnated with grit and do a nice job of polishing .....

    [​IMG]

    The stock ports just cry out for some attention. They're rough sand cast with lumps, bumps, and casting flaws. The areas around the valve seats are full of tooling and machining marks .....

    [​IMG]

    Some time spent with the Dremel can really improve upon this .....

    [​IMG]

    I do just as thelowlife said, leaving the exhausts smooth but texturing up the intakes after smoothing .....

    [​IMG]

    [​IMG]

    After doing mine, I needed to re-jet slightly (one down on the pilots, one up on the mains) which is telling me I did alter the flow characteristics somewhat. I think the bike runs a bit better and stronger. It's not a night and day difference but I do feel it's an improvement. Worth the effort I think.
     
  12. tommerr

    tommerr XS650 Member

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    I will spare no effort. I remember damaging one head in my first screwed up efforts. I accidentally ground on the valve guides. Did this destroy them? Perhaps not but I am a firearms engraver and small details are important. Should the valve guides be left in place to protect the hole? Should the valve guides be replaced after polishing? I suspect that the original guides will protect their holes from damage. At this point in time, should the guides be replaced as a matter of course? Time goes on and wear and tear happens. My engine is torn down. I feel that now is the time for the nitty gritty details. I see bronze guides for sale. Your opinions on guides I request.

    Your guidance is highly valued.

    Tom
     
  13. Bigfeet

    Bigfeet to many projects

    I like it!! I hope you post some pictures because that's on my bucket list of bike builds.
     
  14. tommerr

    tommerr XS650 Member

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    Check out the Kiwi flat spring front forks. They are pricing out a set for me as I type. I am short and I lowered my bike two inches front and rear. They have the dimensions if you are interested. Bear in mind that these are not cheap. Back to porting. How polished is polished? I suppose that I could buff them but I am suspicious that there is a point of diminishing returns where either negative results may happen or my efforts may be better spent elsewhere.
     
  15. Jack

    Jack XS650 Junkie

    On the intakes I use 36grit for a barrier finish,it's promotes just enough resistance in creating a higher pressure point behind the low pressure front in keeping the mixture suspended in the main airstream. For the exhaust ports there really is no benefits to highly polished port finish cuz over time carbon will build up in the ports.
     
  16. Jack

    Jack XS650 Junkie

    Nicking the guides won't cause any harm and I keep the guides in place just to avoid damaging the guide bores. On the exhaust guide,you can reduce it's length to that of the intake to reduce turbulence around the valve stem to speed up roof activity. Those bronze kibblewhite guides come with a hefty tag for sure,at a time you could get them for a little over $9 a pop at a minimum $100 purchase.
     
    Last edited: Jan 14, 2012
  17. tommerr

    tommerr XS650 Member

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    I was wondering about the hefty price tag. I'm age 62. Things that will last 100 years are somewhat a mute question at my age. Never the less, "The very best is adequate and too much is not enough". What if I do live to be 162? Never mind.
     
  18. XSLeo

    XSLeo XS650 Guru

    Over at the Garage they have a couple very good threads on working the xs650 head. One basic and one more advanced. Pics included. I used them to remove the casting marks and clean up the rough stuff. Not hard to do, just take out the minimum amount to clean it up and you'll be fine.
    Leo
     
  19. tommerr

    tommerr XS650 Member

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    The Garage pictures are gone but I get the picture.
     
  20. XSLeo

    XSLeo XS650 Guru

    Been a couple years ago I did my head so it's been that long since I looked at the threads. To bad the pics are gone. They helped understand the job better.
    Leo
     

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