ADVrider

ADVrider (http://www.advrider.com/forums/index.php)
-   Airheads (http://www.advrider.com/forums/forumdisplay.php?f=85)
-   -   Cam shaft choice small seal R90/6 (http://www.advrider.com/forums/showthread.php?t=846244)

chasbmw 12-05-2012 06:45 AM

Cam shaft choice small seal R90/6
 
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/produc...als-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

RGregor 12-05-2012 09:25 AM

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

supershaft 12-05-2012 09:54 AM

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?

chasbmw 12-05-2012 10:50 AM

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

RGregor 12-05-2012 11:12 AM

Quote:

Originally Posted by chasbmw (Post 20183854)
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

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

chasbmw 12-05-2012 11:16 AM

Thanks I will check the thread,

supershaft 12-05-2012 12:27 PM

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 . . . .

RGregor 12-05-2012 12:42 PM

Quote:

Originally Posted by supershaft (Post 20183505)
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?

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.

supershaft 12-05-2012 07:33 PM

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.

RGregor 12-05-2012 11:38 PM

Quote:

Originally Posted by supershaft (Post 20187376)
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.

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....hp?en_kontakte
I would regard this as very simple.

chasbmw 12-06-2012 05:38 AM

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

bmweuro 12-07-2012 01:43 AM

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

http://sphotos-b.xx.fbcdn.net/hphoto...93973318_n.jpg

http://sphotos-a.xx.fbcdn.net/hphoto...61916818_n.jpg

chasbmw 12-07-2012 09:30 AM

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.

supershaft 12-07-2012 10:36 AM

Quote:

Originally Posted by bmweuro (Post 20195725)

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.

bmwrench 12-07-2012 06:35 PM

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.


Times are GMT -7.   It's 03:29 AM.

Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014