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Old 12-12-2012, 04:43 AM   #46
RGregor
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Quote:
Originally Posted by supershaft View Post
But back to the subject of comparing cams: As soon as Bob times some more cams and posts the results, some of us need to time our cams and see if we can duplicate the results.
Just a suggestion, as you are going to time the various cams to compare them:
Additionally measuring duration at ~70% lift may be a better indicator of the profile and of filling than the duration at 1mm lift and max lift only.
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Old 12-12-2012, 10:06 AM   #47
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I took the R90/6 to the Dyno today to get some baseline readings prior to changing the camshaft.

Here is the Torque BHP curve, given i asked Jim to create a touring engine with good even torque, then i think that he fulfilled his remit.



This chart shows BHP with the bottom line showing airfuel ratio, it all looks good to me. The lean condition spike at low revs may be due to the sniffer not reacting well or low revs, but also might reflect the surging I get at low revs
and at slightly opened throttle. This may be rectified when I replace the throttle shaft O rings as I think this might be the cause.



I will be changing the camshaft In January so I will redo the dyno runs after i have got a few miles on the modified engine. No other changes are planned.
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chasbmw screwed with this post 12-12-2012 at 10:22 AM
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Old 12-12-2012, 12:48 PM   #48
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Most likely bigger needle jets are what you need. 266's up to 268's for instance. Or maybe 268's up to 270's? I would try bigger mains too. 140's to 145's for instance? A different cam might really change your off idle jetting. I needed to go from 268's or 270's (I don't remember right now) down to 262's when I put a 336 in my bike. A lot more reversion really richened it up there. It idled and blipped SO much better after doing that!
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Old 12-16-2012, 09:14 AM   #49
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Quote:
Originally Posted by 983Bob View Post
Once I've built this motor, I'll do the specs. on the 344, 330, Schleicher cams 336BMW and 320BMW cams.
Just to mention it: the 320 BMW cam has nothing to do with the 320 Schleicher cam (or HPN).
The BMW cam AFAIK has been used for bikes that went to Switzerland and reason were not performance issues but exhaust emission.
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Old 12-16-2012, 10:05 AM   #50
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I have searched at length for the BMW 320 cam. I'm almost certain it used to be listed on their microfiche. Does anyone have part numbers?
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Old 12-16-2012, 10:11 AM   #51
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Originally Posted by bmwrench View Post
I have searched at length for the BMW 320 cam. I'm almost certain it used to be listed on their microfiche. Does anyone have part numbers?
According to this page (maybe interesting in general)

http://www.mirotec.org/frames/frame.htm

the part No. is 11311338498

The parts catalogue delivers this

http://realoem.com/bmw/partxref.do?p...338498&lang=en

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Old 12-19-2012, 03:30 AM   #52
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Originally Posted by RGregor View Post
Never heard of a BMW race cam other than the 336.
Helmut Daehne raced the 336 and then (early 70ies) he was working in the test department.
He probably had access to all parts available at BMW.
I can ask him if that's of interest.

BTW: I asked him about the 336 and he still is very fond of it. Used it even in his enduro "without disadvantages".
According to HD the 336 was the only sports/race-cam from BMW.
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Old 12-20-2012, 03:56 AM   #53
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Norton gave their timing figures two ways, for their racers.

The 339 degree inlet cam in the short stroke 500 40 M was either 74 / 85 at two thou valve clearance, or 0.280 lift at TDC, 0.315 lift at BDC, with the same 2 thou clearance.

If Siebenrock did the same it would make Supershaft , and probably a few more of us , a lot happier.

And if you read this , 983 Bob, any chance of giving us the lift figures at TDC / BDC with 2 thou clearance, on the cams you check?

And a word of caution - if you intend using a 'Modern" cam which bashes the valves open and bangs them shut it is advisable to use modern valves, seats and springs which are up to the task, after all they are what make the use of "Modern" cams possible.

Ritchie at Moorespeed has what you need.

http://www.moorespeed.co.uk/moorespeed/bmw-engine
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Beemerboff screwed with this post 12-20-2012 at 04:17 AM
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Old 12-21-2012, 08:32 AM   #54
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Ritchie provides absolutely no information about the 'sports cam' that he uses in some of the tuning schemes.

My definition of a modern cam is one designed in the last 20 years, I don't mean a can that will give the valve train components a lifespan measured in nano seconds!

Who can give me an idiots guide to setting up and timing a new cam on an airhead? I sort of think that if I am asking the question, then I should I be thinking of doing it?
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Old 12-21-2012, 12:45 PM   #55
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The reason I do not give info on cams is because it would just go on and on, it is down to you to come to me with engine spec, what you want it to do and rpm limit. I have over 8 cams to pick from. they are all from the original chill cast blanks and run standard followers with no problems, even the race cams, the only thing is all my cams are the latest type.
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Old 12-21-2012, 01:13 PM   #56
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It seems we have moved past the notion that some cams are 'old fashioned' for being mild. I certainly hope so since mild cams and cams with ramps too steep and lift too high have been around for almost as long which is a long time! Asymmetrical timing seems to be a newer thing but a lot of strong performing race cams out there are still symmetrical. What does the 'latest type' mean? Other than slightly different timing that very well could have been tried years back?
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Old 12-21-2012, 01:18 PM   #57
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Quote:
Originally Posted by chasbmw View Post
Ritchie provides absolutely no information about the 'sports cam' that he uses in some of the tuning schemes.

My definition of a modern cam is one designed in the last 20 years, I don't mean a can that will give the valve train components a lifespan measured in nano seconds!

Who can give me an idiots guide to setting up and timing a new cam on an airhead? I sort of think that if I am asking the question, then I should I be thinking of doing it?
There are lots of books on it. I suggest reading at least a couple of them. It's what I call a lot of work and very tricky if rock solid, repeatable results are what you are after which I hope you are since a degree matters and that is very easy to fudge!
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Old 12-21-2012, 01:43 PM   #58
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The latest type to me means a slot drive in the front for the ignitor.
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Old 12-21-2012, 02:05 PM   #59
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The latest type to me means a slot drive in the front for the ignitor.
Awesome! I always call them the 'later' type since they came out with that 33 (?) years ago but I thought we were talking about timing so . . . .
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Old 02-25-2013, 02:14 PM   #60
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Chasbmw,


Any update on how you like your 324 CAM
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