Lightening Airhead Lifters

DeutschMark · 12-03-2009, 06:41 AM

Has anybody lightened airhead lifters with any success? The old Dr. Curve article mentioned elongating the oval hole on the lifter.

If anyone has done this, how much weight is safe to remove?

Thanks.

Stagehand · 12-03-2009, 08:57 AM

every little bit helps, I guess.

No idea.

Wirespokes · 12-03-2009, 10:48 AM

Never thought of it. I wonder about using titanium? Would there be a metalurgical problem between them and the cam?

skrub · 12-03-2009, 04:18 PM

I once aponatime owned one of the Butler&Smith short rod factory race engines. It did not have the utra trick lifters. I have heard thay where titanium and had to be welded in a vacuum chamber.

Some one once made a lifter with a ti button on the top to prevent the push rod from pushing through because of the high spring rates used on the hugh cams. I had an idea to use a R65 lifter its a cup the push rod rides in the bottom. Then the side can be drilled or slotted with no fear of damage. The push rods then need to be longer, Jegs sells a kit ala cut to fit for a hemi eng.

bmwhacker · 12-12-2009, 08:43 PM

Seems like you would only lose a couple of grams....pass on breakfast and take a good dump and you'll likely lose more.......

BrianK · 12-12-2009, 08:51 PM

Quote:

Originally Posted by bmwhacker

Seems like you would only lose a couple of grams....pass on breakfast and take a good dump and you'll likely lose more.......

Yeah, but that's not reciprocating weight.... at least, I HOPE NOT!

bmwhacker · 12-12-2009, 09:00 PM

Quote:

Originally Posted by BrianK

Yeah, but that's not reciprocating weight.... at least, I HOPE NOT!

bmweuro · 12-12-2009, 10:32 PM

I have built a lot of airhead race motors in the past 25 years and this is an area I would not tuch on a street bike. If you ever rev the motor you will crack a lifter and on the street you will never notice the added performance. If your looking for cheap reliable horse power in a Boxer you can do 2 things.

up the compression and port match the heads.

Rob Farmer · 12-12-2009, 11:15 PM

Siebenrock have light weight cam followers, Valves and pushrods. Not cheap though.

Beemerboff · 12-13-2009, 05:22 AM

The real problem is that the lifters dont get a straight push at the rods , so for a top race engine you want to be welding up the holes and re machining them so that they do- said to be worth 500 revs by those that should know.

DeutschMark · 12-13-2009, 07:08 AM

Quote:

Originally Posted by bmweuro

I have built a lot of airhead race motors in the past 25 years and this is an area I would not tuch on a street bike. If you ever rev the motor you will crack a lifter and on the street you will never notice the added performance. If your looking for cheap reliable horse power in a Boxer you can do 2 things.

up the compression and port match the heads.

I've already got the compression part covered. I've got a set of late 9.5 pistons and I'm going to dual plug, so I'll bump it a little more. I also have a Scheffer/Edelweiss asmmetrical cam ordered and already have some Mikuni carbs. This should be a peppy airhead!

When the heads are done I'll have the machinist use 44mm intake valves.

As far as the port matching goes, I pulled the heads and planned to do a little smoothing and casting flash removal, but there doesn't seem like there is much to remove. The intakes are clean, with only a little casting flash. There is a small hump on the bottom of both intake ports that could be smoothed over and a booger size piece of flash on the short radius of one intake. Is this what you are referring to?

On the exhaust side, there is a small step outward all of the way around the area where the head transitions to the spigot. Are there any gains to be had by removing this?

RecycledRS · 12-13-2009, 07:48 AM

The ridge meets flush with the exhaust pipe. Any smoothing you do should be done with a small length of exhaust tubing in place to match up to first.

bmweuro · 12-13-2009, 10:25 AM

Quote:

Originally Posted by DeutschMark

I've already got the compression part covered. I've got a set of late 9.5 pistons and I'm going to dual plug, so I'll bump it a little more. I also have a Scheffer/Edelweiss asmmetrical cam ordered and already have some Mikuni carbs. This should be a peppy airhead!

When the heads are done I'll have the machinist use 44mm intake valves.

As far as the port matching goes, I pulled the heads and planned to do a little smoothing and casting flash removal, but there doesn't seem like there is much to remove. The intakes are clean, with only a little casting flash. There is a small hump on the bottom of both intake ports that could be smoothed over and a booger size piece of flash on the short radius of one intake. Is this what you are referring to?

On the exhaust side, there is a small step outward all of the way around the area where the head transitions to the spigot. Are there any gains to be had by removing this?

What year and size motor is this? What are the heads off of?

DeutschMark · 12-13-2009, 10:36 AM

Quote:

Originally Posted by bmweuro

What year and size motor is this? What are the heads off of?

1989 1000cc with original heads.

12-03-2009, 06:41 AM	#1
DeutschMark ^OP Full Tilt Boogie Joined: Aug 2008 Location: Grand Haven Oddometer: 196	Lightening Airhead Lifters Has anybody lightened airhead lifters with any success? The old Dr. Curve article mentioned elongating the oval hole on the lifter. If anyone has done this, how much weight is safe to remove? Thanks. __________________ 89 BMW R100RS 97 Suzuki DR350

12-03-2009, 08:57 AM	#2
Stagehand +/- V TDSPP Joined: Oct 2004 Location: "Poughkeepsie?!?!" Oddometer: 19,849	every little bit helps, I guess. No idea. __________________ What to do... What to do...

12-03-2009, 10:48 AM	#3
Wirespokes Beemerholics Anonymous Joined: Jul 2002 Location: Jackson's Bottom Oregon Oddometer: 7,354	Never thought of it. I wonder about using titanium? Would there be a metalurgical problem between them and the cam? __________________ Wanted: Dead, smashed, crashed or trashed gauges BMW GAUGE REPAIRS - TACHSPEEDOCLOCKVOLT METER PODs & LIGHT BOARD*

12-12-2009, 08:43 PM	#5
bmwhacker Still on 3 wheels Joined: May 2009 Location: MONTANA NATIVE from NATIVE MONTANA Oddometer: 3,372	Seems like you would only lose a couple of grams....pass on breakfast and take a good dump and you'll likely lose more....... __________________ http://jupiterhack.blogspot.com Living proof you shouldn't play with matches

12-13-2009, 05:22 AM	#10
Beemerboff Beastly Adventurer Joined: May 2005 Oddometer: 2,051	The real problem is that the lifters dont get a straight push at the rods , so for a top race engine you want to be welding up the holes and re machining them so that they do- said to be worth 500 revs by those that should know. __________________ Adelaide Hills, Australia. 93 R100 GS, 77 R75/7 ,70 BSA B44VS, , 86 R80 G/S PD, 95 BMW Funduro F650 ST

12-03-2009, 04:18 PM	#4
skrub Gnarly Adventurer Joined: Jan 2008 Location: Sanford Mich. Oddometer: 258	I once aponatime owned one of the Butler&Smith short rod factory race engines. It did not have the utra trick lifters. I have heard thay where titanium and had to be welded in a vacuum chamber. Some one once made a lifter with a ti button on the top to prevent the push rod from pushing through because of the high spring rates used on the hugh cams. I had an idea to use a R65 lifter its a cup the push rod rides in the bottom. Then the side can be drilled or slotted with no fear of damage. The push rods then need to be longer, Jegs sells a kit ala cut to fit for a hemi eng.

12-12-2009, 10:32 PM	#8
bmweuro Mad Scientist Joined: Nov 2003 Location: Chico, California Oddometer: 2,943	I have built a lot of airhead race motors in the past 25 years and this is an area I would not tuch on a street bike. If you ever rev the motor you will crack a lifter and on the street you will never notice the added performance. If your looking for cheap reliable horse power in a Boxer you can do 2 things. up the compression and port match the heads.

12-12-2009, 11:15 PM	#9
Rob Farmer Beastly Adventurer Joined: Aug 2002 Location: Loughborough, Leicestershire. England Oddometer: 3,733	Siebenrock have light weight cam followers, Valves and pushrods. Not cheap though.

12-13-2009, 07:48 AM	#12
RecycledRS Along for the ride Joined: Nov 2008 Location: Vancouver Island Oddometer: 912	The ridge meets flush with the exhaust pipe. Any smoothing you do should be done with a small length of exhaust tubing in place to match up to first. __________________ __________________________________________ "There's a fine line between a skinning and a shearing"

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: .
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode