ADVrider

Go Back   ADVrider > Bikes > Old's Cool > Airheads
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-22-2013, 09:22 AM   #61
Renner
combustophile
 
Renner's Avatar
 
Joined: Jul 2007
Location: sunny SoCal
Oddometer: 1,868


danke, Dirk
__________________
"If you want to fix it with a rock, you have to stick to stone-age technology" -Anton
"...solving the latest crisis that is preventing my Airhead from taking me to the bar." -Beater-
Renner is offline   Reply With Quote
Old 02-22-2013, 10:30 AM   #62
Carl
,,,
 
Carl's Avatar
 
Joined: Oct 2001
Location: South Tejas
Oddometer: 753
Quote:
Originally Posted by Edelweiss-Motorsport View Post

>>snip<<<

And yes it is don quijote against the windmill - but it is priceless fun to have.

This is what it is all about - just let us all together have some good fun with this wonderful BMW engines, and then best possible share it...

Dirk
WOW Dirk! Many thanks for your informative technical well researched and documented posts. Your 'real' life technical data runs circles around the 'butt dyno' stories.

Questions on the CNC porting... Are you CNC'ing the ports because you already determined an ideal efficient rework and want exact duplication? To get head symmetry? To do heads in quantity batches? Somebody likes to program machine code? or...

Thanks again,
Carl
__________________
http://www.flyingtpot.com/

Carl is offline   Reply With Quote
Old 02-22-2013, 10:42 AM   #63
Airhead Wrangler
Adios Mexico
 
Airhead Wrangler's Avatar
 
Joined: Mar 2008
Location: Back in Seattle, FINALLY
Oddometer: 6,282
Quote:
Originally Posted by Carl View Post
Questions on the CNC porting... Are you CNC'ing the ports because you already determined an ideal efficient rework and want exact duplication? To get head symmetry? To do heads in quantity batches? Somebody likes to program machine code? or...
It seems like the best way to get consistent and well balanced results in two heads. I also had some questions about what gets done to the ports. Care to go into a bit more detail about the port work, Dirk? Do you have any photos? We like photos here.

Thanks for bringing your experience to the table.
__________________
R80ST Gets The HPN Treatment
Seattle to TDF on an airhead

Current rides: HPN #834, '93 R100GSPD "red rocket", '73 R75/5 Toaster mongrel, '80 Ducati Pantah 500SL, '92 DR350, '67 Honda SS50, '80 Honda Chaly.

Airhead Wrangler screwed with this post 02-22-2013 at 10:51 AM
Airhead Wrangler is offline   Reply With Quote
Old 02-22-2013, 12:12 PM   #64
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,015
Why spend money on pistons? To save money on rods and machine work for basically the same effect in the end.

I totally agree about head material and heat but I have seen no problems for removing head material.

R100 pistons never fail? I have seen the top ring groove wear many times over. Take a look. I guess you are talking about Euro standard 9.5:1 pistons? Not that the ring groove doesn't wear on them but I am trying to keep track of the machining involved going with 1.5mm longer rods. US models have 8.5:1 CR. Do you use a different rod length for those pistons? You call it squish band and I am calling it CR. I know the importance of squish band but it sure doesn't sound like you are decreasing squish band and at the same time not raising CR?

I hope aluminum gaskets leak less oil than I have seen numerous copper gaskets leak.

If your putting a 1.5mm longer rod under a stock 9.5:1 piston you are running more static CR than I am on my street bike by far. My 9.5:1 CR pistons are not running too hot with .025" taken off dual plugged heads. Neither are my heads. Meanwhile you are running .060" longer rods.

I am not worried about big bores. I am just going by what I have seen. I would think you would have to cast your own cylinders to go that far out but unfortunately the cylinder studs are in the same place as before. Therein is most of the troubles I have seen as far as oil leaks is concerned. Cylinder wall stability is another issue that takes some miles to show up in my experience. Not low miles just left the shop troubles but a few more miles down the road troubles.

From what I have seen I agree about with you about two into ones. The tradeoffs favor two into one on the big bore race bikes. 500cc? I don't know. I think I know what you are saying about quicker rev with two into ones.

supershaft screwed with this post 02-22-2013 at 12:23 PM
supershaft is offline   Reply With Quote
Old 02-22-2013, 01:47 PM   #65
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,015
Quote:
Originally Posted by RGregor View Post
Servus Dirk!

Also, jetzt musst Du nur noch was gegen die 336er Nocke schreiben, dann hast Du im Zeitraffer alle Punkte infrage gestellt, für die sich Herr SS hier stark macht. Ohne die Alternativen überhaupt zu kennen.

Und sonst, alles im Lot?

Gruß aus München

Rudi
I missed this one! Real nice RG. Still can't get over someone discussing matters versus just saying yes to many matters that will always be open to discussion. Discussions do not HAVE to include blind brown nosing.
supershaft is offline   Reply With Quote
Old 02-22-2013, 01:58 PM   #66
Carl
,,,
 
Carl's Avatar
 
Joined: Oct 2001
Location: South Tejas
Oddometer: 753
Ich verfehlte dieses! Wirkliches nettes RG. Nicht über jemand kann das Beraten über von Sachen gegen gerade ja sagen an viele Angelegenheiten noch gelangen, die immer zur Diskussion offen sind. Diskussionen müssen das blinde braune Riechen nicht umfassen.
__________________
http://www.flyingtpot.com/

Carl is offline   Reply With Quote
Old 02-22-2013, 02:00 PM   #67
Edelweiss-Motorsport
Adventurer
 
Joined: Feb 2013
Location: Essen Krautland
Oddometer: 41
Samcho Pansa

Hey all,

Here we go:

Rudi - Hey ho my dear friend - here all is upright and i hope it is the same for you !?

Charles - the 336 deg. BMW profile still is an OK cam but I would never use it in any case if I have the freedom to choose. If it is builded in an engine and my customer insist to keep it i know how to make it work. But it will always be a compromise compared to what you can get on hand today.

Not talking mumble fumble here are some hard data: this cam has a relatively low total lift combined with a lot of duration and in relation a massive overlap.

Despite the huge duration the lobe area is not too big which all in all is exactly what you have on an outdated old maximal unmodern cam profile.

It is very soft to the valve train since acceleration - positive as well as negative is quite small, so you can rev up to the sky but without good reason; just pumping cold air to get a little hot.

What you go for nower days is less total duration much more lift and much more duration in the high lift area, this generates a reasonable lobe area and due to the outcoming support to the volumetric efficiency of the system the middle pressure comes up generating torque and after all the power which turns the wheel...

So all this said holding in mind that we are talking about a pure racecam as the 336 deg. was constructed as one to be. To be used in a street bike would be suboptimal all over. It is for example not taking any restrictive exhaust - you need an most possible open absorber system. Put it into an R100GS with a std. exhaust and std engine and it is the perfect desaster.

Here some little basics of cams and exhausts:

One very specific point in getting a cam workable together with an exhaust is the point of symmetrical overlap, let's say the point where both valves are in max overlap lift.

If you have an quite silent reflector system this point is best somewhere before TDC.

If you are using a bolt on from a cataloque sport system with an absorber you put this overlap situation directly on TDC.

If you go full race and you are able to build a system custom made to your application with the correct primary and secondary lengths you put the symmetrical overlap somewhere after TDC.

All this just for the orientation and just for the sensible ones in the audience...!

So going to some good double valve springs - which are not too hard on top lift but hard enough at the point of maximal positive acceleration at the opening ramp where you need about 35 to 55 Kg depending on the profile combined with tapered aluminium pushrods then some light lifters and you can do miracles to our beloved flat twins with a modern cam.

Not saying there are no people out there happy with the old brother 336... this is all depending on what you expect and what you know.

Jimmi Hendrix would say: are you experienced ?

For those of you who are also Porsche addicts like me - it is the same as the carrera 6 cam out of this world, done in the sixties winning a hundred wars but retired in honor.

Renner - bitte sehr !

Carl - yes after decades of testing flow benching and learning that you can't ask anybody but your dyno about how to do it we found out what a porting takes to work on the basis of a std. head from the BMW shelf.

First of all we use the latest head versions with the D shaped exhaust port - like on the R 100 GS ones. We do not use the 70 HP 44/40 RS heads since they are hyped without any reason - go sell them on eBay !

Next - a big valve will always perform out a small valve - but attention there are limits and if you take a step to far your train will drive backwards with the speed of light.

Third - most ports where made of the hands of whoever where destroyed by being way too big. You need just to modify the shape at some specific spots but not the size since the ports are big enough anyhow.

General - do not change the angle of ports or valves, understand the philosophy of your system and support the plus points, do not spend too much time in fighting odds you have to live with.

Conclusion - good tuning is doing just the few essential things that are right, and leaving away all the mistakes that you found on your way and could be done in this wonderful game.

Pordon me for what I say now and please do not missunderstand or get me wrong being arrogant in any way - there is a point where you will not find any answers from any source it is when you go where nobody was before. You will have problems nobody has before and so you have to turn on your headlamp inside this tunnel to find a working way.

Ok - then we started cnc porting because these engines are running on an international basis and so I want a 100 % reproduceable quality on every engine.

Here in Germany you will find a lot of people cutting material out of cylinderheads, but when you ask me how many can do a perfect port I will not need the fingers of one hand to count them.

In my company it is just me porting the heads so it was not possible in the long run without cnc porting - beside the perfect quality:

One man two hands....

We salute you !

Dirk

Edelweiss-Motorsport screwed with this post 02-22-2013 at 03:15 PM
Edelweiss-Motorsport is offline   Reply With Quote
Old 02-22-2013, 03:01 PM   #68
Voltaire
Beastly Adventurer
 
Voltaire's Avatar
 
Joined: Jun 2011
Location: Auckland,New Zealand
Oddometer: 1,196
thanks for posting. My racebike R90 is currently running a 336, stock pistons and a 2 into 2 with Commando mufflers ( great sound) 36mm Dells and an ignitech ignition. Not competitive but lots of fun.
I have a dead R80 motor with some D port heads which I am thinking of putting of the 73 R90. Here in NZ there are no BMW head tuners that I am aware of. Any tuning tips much appreciated
cheers John
Voltaire is offline   Reply With Quote
Old 02-22-2013, 03:36 PM   #69
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,015
I am a late model small port guy for the same reasons.

No experience with other cams but I love my 336 in my bike as do many others I know. Lift? They have right at the same lift as many of the new cams available excepting some of the 'race' cams. The 336 is a very compromised cam. That's what I like about it for a street bike. I put mine in a stock '92 R100 engine with 8.5:1 CR except for some Staintune Sport mufflers. Awesome improvement. Way less shifting for a lot more midrange. The more I have modified that same engine for top end, the bigger the midrange gets. They are easy on the valve train. Another big plus for a street bike IMO. If I was racing? I would want more lift but I am not. I still might want just as narrow a lobe to lobe degree but I don't know for sure. A lot of tuners still like narrow lobe centers. Others don't. I do from what I can tell. Narrow lobe center cams are more sensitive to exhaust setups and airbox setups but that isn't a bad thing with the right exhaust and airbox.

Don't get me wrong, I am all for not too much CR and long rods but it sound like you are running a lot more CR than I am and if I went to the expense of new rods they would be a lot longer than 1.5mm longer.
supershaft is offline   Reply With Quote
Old 02-22-2013, 04:05 PM   #70
Carl
,,,
 
Carl's Avatar
 
Joined: Oct 2001
Location: South Tejas
Oddometer: 753
Quote:
Originally Posted by Edelweiss-Motorsport View Post

>>snip<<

Jimmi Hendrix would say: are you experienced ?

>>snip<<

We salute you !

Dirk
OK, first the Zappster and now Hendrix. Please fit in some Can, Amon Düül II, Tangerine Dream, Neu!, Kraftwerk, etc... into your posts.

Thanks!

Carl
__________________
http://www.flyingtpot.com/

Carl is offline   Reply With Quote
Old 02-22-2013, 04:35 PM   #71
chollo9
Screwed the Pooch
 
chollo9's Avatar
 
Joined: Jul 2003
Location: Silk Hope, NC
Oddometer: 990
Quote:
Originally Posted by Carl View Post
OK, first the Zappster and now Hendrix. Please fit in some Can, Amon Düül II, Tangerine Dream, Neu!, Kraftwerk, etc... into your posts.

Thanks!

Carl
Frank Zappa: "All the good music has been written by people with wigs and stuff."
__________________
"It's not that I don't like people...I just find I am happier when they're not around"
chollo9 is offline   Reply With Quote
Old 02-23-2013, 02:58 AM   #72
carpetburn
Gnarly Adventurer
 
Joined: Dec 2009
Location: brisbane
Oddometer: 121
This is an interesting thread right up to the point you start posting in a language i dont speak/understand! Get fucked-posted in english
carpetburn is offline   Reply With Quote
Old 02-23-2013, 03:09 AM   #73
RGregor
User Awaiting Email Confirmation
 
Joined: Oct 2007
Location: Bavaria
Oddometer: 437
Quote:
Originally Posted by carpetburn View Post
This is an interesting thread right up to the point you start posting in a language i dont speak/understand!
You didn't miss anything, it was not related to the topic.
RGregor is offline   Reply With Quote
Old 02-23-2013, 03:42 AM   #74
pommie john
Beastly Adventurer
 
pommie john's Avatar
 
Joined: Apr 2008
Location: Brisvegas, Australia
Oddometer: 1,338
Dirk

I use a 336 in my race bike, it was the only cam really available when I started racing in the mid 1990s.

My understanding is that the design of this cam was limited by the very long pushrods which flex even with the standard road cam.
How do you deal with this when using even greater valve acceleration? Do you have special pushrods?


John
__________________
The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt.
Bertrand Russell
pommie john is offline   Reply With Quote
Old 02-23-2013, 06:46 AM   #75
chasbmw
Beastly Adventurer
 
Joined: Feb 2006
Location: Bath Uk
Oddometer: 1,686
Quote:
Originally Posted by carpetburn View Post
This is an interesting thread right up to the point you start posting in a language i dont speak/understand! Get fucked-posted in english
and don't be so small minded
__________________
Charles
http://i46.photobucket.com/albums/f1...ps6e61ae2e.jpg
R90s 1070 replica, R90/6
1971 Commando Fastback
chasbmw is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 08:52 PM.


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