Cam shaft choice small seal R90/6

Discussion in 'Airheads' started by chasbmw, Dec 5, 2012.

  1. chasbmw

    chasbmw Long timer

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    My R90/6 runs very well, it has been modified a bit, including a fully balanced engine, dual plugged, high compression pistons, light porting,lightened flywheel and I have run the bike for just under 2 years in this configuration, it's very smooth and fuel efficient, but I would a little more top end rush.

    To that end, my mid winter therapy project could include a slightly more exciting camshaft. Looking at the Motoren Israel website the camshafts suitable for my June 1975 small seal R90/6 includes a 320 degree, a 332 degree and a 336degree camshafts all described as 'sports', but no further description as too what the characteristics of these various cams might be.
    http://www.motoren-israel.com/product_info.php?info=p65_332--Sport-camshaft--small-seals-front.html

    I'm not really looking at a full sports cam, just something that will give me a bit more mid and top end, without losing the existing bottom end smoothness. The assymetrical cam on my 1070 bike, seems to work well At all speeds, but it is not made in a small seal version.

    Advice and some real world advice welcome
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  2. RGregor

    RGregor Been here awhile

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    Hello Charles!

    The 336° cam seems to be the BMW profile, as Schleicher doesn't offer a 336° cam for the old bikes (the 336° they offer for the later bikes is a more aggressive profile than the BMW 336°).
    The 320° and 332° cams are Schleicher cams.
    You probably remember the cam thread, there the specs were listed.
    The asymmetrical cam is known to be a combination of the 320 profile for the exhaust and the 324 profile for intake.

    The 320° cam is well known, in the original setup or a 3° advance (then known as HPN 320/3) and regarded as a good profile for a tourer or mild sports engine.
    I know two engines that had the 320° cam installed. Both were very much fun to drive, with a fat torque curve at low and medium revs but still the engines would like to rev high.

    On one of these engines a Siebenrock BBK with the asymmetrical cam was installed. The asymmetrical cam provided more torque at medium revs but above 6k5 rpm, unlike with the 320, fun was over.
    The owner changed back to the 320 and is happy again.

    As to the 332: no personal experience and no hearsay about that. Looking at the specs I would say it's a profile that will pronounce the top more (more lift, more lift at overlap).

    If I wanted to build a smooth touring engine the 320° would be my first choice.

    Rudi
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  3. supershaft

    supershaft because I can

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    I thought a good majority of us came to the conclusion in that cam thread that those specs without a lift check point are not very much help as far as comparing specs or setting up the cams? Even someone's cam doctor graphs were too small to read as far as getting a lift check point out of them?
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  4. chasbmw

    chasbmw Long timer

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    Rudi, many thanks for your helpful reply, I'll wait and see if anyone has any experiance of the 332, but it sounds to me if the 320 would work well on my bike.
    Charles
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  5. RGregor

    RGregor Been here awhile

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    Hello Charles!
    I do have the email address of someone having the 332 in his engine (it's a 94mm*61.5mm short stroke 850cc engine).
    Never talked to him about the cam.
    And I remember that moorespeed has mentioned the 332 in the cam thread here.

    Greetings, Rudi
    #5
  6. chasbmw

    chasbmw Long timer

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    Thanks I will check the thread,
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  7. supershaft

    supershaft because I can

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    If the early 336 aftermarket cam is ground like a BMW 336, I would recommend that. I have installed one in a customer's /6 (a BMW 336) and he loves it. A friend of mine had one in his /6 and he loved his. I love mine in my later model as do others I know. They are great midrange cams! The problem is we really have no way of knowing if they are the same or even if they are what they are suppose to be (the reason tuners time cams to start with!). Someone could time both makes themselves and compare and report. It is a touchy job and just a few degrees do make a difference but . . . .
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  8. RGregor

    RGregor Been here awhile

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    The conclusion was that it is not possible to check the grind of the cam without check point.
    The interesting thing is that quality problems had been unknown as long as Schleicher produced the 336 for BMW ...
    And they still are unknown regarding Schleicher cams. And believe me, they are used a lot.

    In the meantime I had a closer look onto the documentation Schleicher provide and these are equal to those in the BMW documentation:
    Preload the valves 1mm and measure duration after 1mm additional lift.
    The BMW doc says:
    Preload 1/4 turn (no valve play) and measure after 2mm lift.
    #8
  9. supershaft

    supershaft because I can

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    Where is the documentation? In English?

    Grind? What else is there?

    Any good cam manufacturer knows that cams can be ground wrong. That is why most all good cam manufacturers give their specs with a check point so you can check their timing.

    Timing a cam at a rocker arm? I would get real familiar with it at the lifter myself. It makes the job a lot easier and less prone to mistakes IMO.
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  10. RGregor

    RGregor Been here awhile

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    The documentation I have is in german.
    But anyone interested can contact Schleicher prior to buying and ask for all information wanted.
    http://www.schleicher-fahrzeugteile.de/index.php?en_kontakte
    I would regard this as very simple.
    #10
  11. chasbmw

    chasbmw Long timer

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    The plan is to take the bike off to my local dyno jet operator and get a base level run done before Christmas, I can then do the works sometime in January, but a few miles on and then do a second run and see what the difference is.

    This might give some comparative numbers that could be of interest
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  12. Boxer Metal

    Boxer Metal Mad Scientist

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    Here are the specs for all of the aftermarket cams that I know of.

    [​IMG]

    [​IMG]
    #12
  13. chasbmw

    chasbmw Long timer

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    motoren Israel 320 cam purchased".............
    It should be fitted sometime in January. If your are a member of the UK BMW club, the club tool hire scheme has a very wide collection ofBMW tools to help you do this or any other job on what looks to be every bike up to the current 1200s. Not bad for £5 hire fee and costs of return postage.
    #13
  14. supershaft

    supershaft because I can

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    Those specs where pulled up for the previous cam thread. They have no check point. The specs given pretty much have to have no check point if I remember right. Specs with no check point are just about useless. That's why Crane to Megacycle lists a check point with their specs. Unfortunately, there is no standardized check point that the cam industry uses. Since the check point itself drastically changes the specs, there is software out there that will compare specs with difference lift check points. Check points are crucial for comparing grinds, timing grinds, and checking grinds in order to make sure that your cam is indeed timed as it is suppose to be.
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  15. bmwrench

    bmwrench Long timer

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    Since the opening and closing figures add up to the quoted running duration, I would guess that their timing numbers are taken at running clearance, i.e., .006" lift. This would be an unusual way of checking the valve timing, but useable. There are also the lobe centers in the tables. However, I know of no cam grinder who will tell you how quickly the valve is opened. BMW-and most other OEMs of OHV engines- lift the valve very gently, whereas the american hot-rod grinders tend to open them as quickly as the piston position will allow.

    You can do all the measuring possible, but only running a cam will tell you how it works. Anything else is speculation, albeit laced with experience.
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  16. supershaft

    supershaft because I can

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    Those specs are probably taken at 0 lift. I know from experimenting with a Rotax cam (with much longer ramps than many cams made for the engine) that just a few thousandths of an inch can equate a lot of degrees at the crank. The end result was a short track bike that was a LOT easier to get started at the track! As far as I understand the process, no manufacture can even come close to guaranteeing timing just off the round of the cam. It is impossible to grind them that accurately right there. That's the whole reason for the check point. How fast they open a valve? That depends on what lift check point they use. The higher the check point, the more revealing it becomes in that regard. Then, of course, you can time the cam yourself and know exactly how the cam is opening the valve.
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  17. Boxer Metal

    Boxer Metal Mad Scientist

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    Correct. I posted this in a previous thread and they came from Motoren Isreal.
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  18. RGregor

    RGregor Been here awhile

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    I'm wondering what the goal of this fruitless discussion is.
    You are discussing incomplete data a reseller provides and are complaining they are incomplete and thus useless.
    And blame the manufacturer and the product for that.

    Does that make sense?

    The only way to find out if the information the manufacturer provides come up to your standards would be to get the information directly from there, study them and judge then.
    This way everyone here would benefit.
    And the effort for that would really be minimal.

    Everything else has the bad taste as if motivation for this discussion is something completely different.
    #18
  19. Renner

    Renner combustophile

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    I believe what you are referring to is known as self-aggrandizement
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  20. chasbmw

    chasbmw Long timer

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    I think that we are all agreed that if SS needs further information about the various cams he needs to contact the manufactures oirect and ask them nicely. I'm sure that they will reply in English. I seem to remember that contact details are in the previous cam thread.

    Meanwhile I will let the dyno do the talking, in that we will have before and after cam change figures on my R90/6. I won't be making any other alterations to the bike. Yes I know that the same bike on the same dyno on different runs will give slightly different figures, but the odd BHP here or there is immaterial, I'm interested in seeing how the cam changes the power delivery from the engine, so I would hope to increase in torque over a wide rev band.

    For those who are interested, the bike was fully rebuilt just under 2 years ago, it is stock apart for 10.1 Wossner lightweight pistons, dual plugged with a Sachse ignition, a lightened flywheel and it has had the ports cleaned up. The engine was balanced Carbs and exhaust are stock. The bike runs very well at the moment.

    It might well be that I will change the camshaft and will think that it's really brilliant, goes like a MOFO etc etc, but if the dyno says not much of a change, then I will just have to accept that the reality was that this cam change did not make much of a material change to how the bike performs!
    #20