New 336° cam from BMW

Discussion in 'Airheads' started by RGregor, Dec 24, 2012.

  1. mendoje

    mendoje Been here awhile

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    #61
  2. supershaft

    supershaft because I can

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  3. mattcfish

    mattcfish R90X

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    #63
  4. mendoje

    mendoje Been here awhile

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    I have a lathe, all the right measuring tools and instruments, and I'm ready to plunk down my card to buy one. Referring to this sketch, at the peak of each lobe, we're looking for taper from back to front across the face, right?

    [​IMG]
    #64
  5. jbcaddy

    jbcaddy Long timer

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    That price was making me think yes, but they do not have any for /5. out of stock for years :cry
    #65
  6. supershaft

    supershaft because I can

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    Better yet, ask the parts guy to get out his plastic parts guy caliper and measure it for you. There are at least two tapered lobes there to compare the tapered lobes and the flat lobes if they have any.
    #66
  7. supershaft

    supershaft because I can

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    Yes.
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  8. supershaft

    supershaft because I can

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    What's retail now? That can't be much over dealer? When they are ground right they are awesome cams as you now know too! They do it all. Especially upper midrange! Right where I ride all the time. Man I am loving my new setup with my old 70k miles on it now 336!
    #68
  9. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    I bought a bean can 336 about 4 years ago, but ended up using a pre bean motor so had the local cam expert convert a 308 to 336, which included making a set of 'masters'
    More recently got him to convert a R65 cam to 336 as well for a 500 race motor project.....and yes the phasing was taken into account....[​IMG]
    You can see where material has been added.
    Out of curiosity I put the vernier across the lobes and yes there is a taper.
    The 336 in the R90 runs ok but I have not been able to get a good idle, not really an issue in a race bike, pulls really well up to the rev limiters cut out 7500. I used to use the tach but they read about 500 rpm high from memory, with the Ignitech you can read the RPM off the laptop during set up.
    #69
  10. supershaft

    supershaft because I can

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    Did you have your 336's ground straight up or advanced 3*? I have no experience getting 336's timed straight up to idle. Advanced 3* I have gotten good idles out of three that I have set up and I have seen good idles out of other 336's as well. I would start with making sure your valves aren't leaking AT ALL. I sure would be sure and time copied grinds to in order to make sure what you got!

    Why set your rev limiter so low? Piston speed is super safe until you are real close to 9000rpm. If your valves aren't floating and they shouldn't be with titanium spring retainers, rev it higher for more power. If it isn't making more power up there you still might be able to use the over rev to your advantage at some tracks. 336's have good usable over rev.
    #70
  11. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    Good points,I'm not sure on the advance, have to check with my Guru on that.... I have bugger all experience outside stock setup.
    The motor was put together on a real low budget just to see if riding on the track was for me, the valve train is stock at this stage. Been looking at SS Manley valves ( lighter), titanium retainers and beehive springs.Another 1000 rpm would sure be useful, would be able to stay in front of the featherbed Dominator 850 after passing him on the corner under brakes....:D
    Had a good season with the old girl, surprised quite a few, expecially the Harleys.
    #71
  12. DanMay

    DanMay Adventurer

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    How did the 336 work out in your 500cc race motor ? I am interested in your experience, and curious if the smaller displacement and valve size will benefit from the 336 profile. I am currently racing a R50/5 with the stock camshaft.

    Daniel
    #72
  13. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    Its still on the bench at the moment, the rules here allow you to run parts that " look the same"....
    So its really going to be an R45 motor with R65 heads, 336 cam and a light valve train.
    I have not heard of anyone doing this....probably good reason.
    Cylinder wall needs a smidgen taken out but shrouding could be an issue....as might the 36mm inlet ports.....its suck it and see territory.
    For a r50/5 the 308 cam would probably work better .....once again pure supposition.
    #73
  14. AntonLargiader

    AntonLargiader Long timer

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    To me, a 1070 kit with Mikunis would look [sort of] the same as an R50. Close enough!
    #74
  15. DanMay

    DanMay Adventurer

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    <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>

    <o:p></o:p>
    Ha ! I wish. I run in AHRMA Production Lightweight , and I must keep the same stroke and bore (plus a small overbore is allowed). I am running the R50/R60 /5/6 Bings, those are the only allowed carbs. Then again, you know all this because I believe you have built a R75/5 AHRMA racer in the past...<o:p></o:p>
    <o:p></o:p>
    There is not a lot of information on making the R50/5 go fast and keeping it a 500cc. Most just suggest putting a 600 or 750 top end on it. That is fine for the street, but I need to keep it 500cc and production looking from the outside. A lot of questions:<o:p></o:p>
    <o:p></o:p>
    Will the 600 heads work ? Or will the valves hit the cylinder walls ? What is the best valve size for the 500 ?<o:p></o:p>
    What is the best cam profile for the 500cc displacement ?<o:p></o:p>
    What is the best way to raise the compression ? Dual plugging is not an option so I am worried a piston with too much dome will not provide an efficient burn on a single plug.<o:p></o:p>
    <o:p> </o:p>
    So many options, so little time…<o:p></o:p>
    <o:p> </o:p>
    Daniel<o:p></o:p>
    <o:p> </o:p>
    <o:p></o:p>
    <o:p> </o:p>
    #75
  16. bmwrench

    bmwrench Long timer

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    Using heads and/or cylinders off a 70.6mm stroke motor won't work on an R45/R65 case. The difference in stroke makes developing a decent compression ratio difficult. If you are going to use the R45 cases and crank I suggest using the stock heads with valves from an R65. Bore to 1mm oversize; you can get pistons from a number of aftermarket sources.

    On the other hand, you could really cheat, taking the motor out to 750cc. As long as you don't look significantly faster than the other bikes, or win too often, no one should ask for a tear down:evil
    #76
  17. DanMay

    DanMay Adventurer

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    I need to keep it legal, 500cc max. With a R50/5 bottom end, pistons, and jugs, can you use R60/5/6 heads ? Would the larger valves help or hinder the performance ? Or would it be better off sticking with the R50/5 heads and just do a good port job ?
    #77
  18. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    Yes.
    Its an R65 with 450 cylinders and pistons, finding the 450 kit was hard enough and they were never imported to down under.
    Where can i get oversized pistons?:evil
    cheers
    #78
  19. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    :rofl:rofl look the same but with the correct capacity, and no Jap parts are allowed.
    #79
  20. Padmei

    Padmei enamoured

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    Thanks for that Mendoje. I (& prob others not so engineeringly minded) now understand what the discussion is about:thumb
    #80