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 08-31-2013, 01:03 PM   #1
Ace_Cafe_Rat OP
Rogue Adventurer
 
Ace_Cafe_Rat's Avatar
 
Joined: Mar 2007
Location: Undisclosed Location in the Nuevo Mexico Desert
Oddometer: 223
Question More power for my new Airhead Hack? Please advise me.

Greetings Adventurers,

In a few short weeks I will take delivery on my long-awaited Airhead Hack. It is based on a 1984 "GS'd out" R80ST and a tricked-out M72 Sidecar from Dauntless Sidecars, with an oil cooler, leading-link fork, new monoshock, second front disc brake and a car-rear-tire conversion added by Lowell Neff Engineering. In addition to the GS tank, seat and luggage rack the previous owner installed he also put 1000cc nik. cylinders on the bike.

I have owned a Perry Bushong built R100/7-based Airhead hack since 2008 so I know I will want more power for this new rig. This is primarily to avoid becoming a hood ornament on the Interstates I must endure to reach the fun/unpaved roads in The Four Corners states. But also for the long distance trips (3 Flags for example) that I aspire to. I have been researching power mods for Airheads online (including here @ ADV Rider) and have been very impressed @ the expertise of the Airhead Community here.

So I am wondering if a 1070 Big Bore Kit might be the way to go? Probably do that along with dual-plug heads, larger valves, larger carbs and a less restrictive exhaust? Or would the strain of pulling the sidecar make a 1070cc kitted engine a grenade?

Your words of counsel will be much appreciated.

Ace Cafe Rat
__________________
"Curse your sudden but inevitable betrayal!"

Hoban "Wash" Washburne - Firefly & Serenity
Ace_Cafe_Rat is offline   Reply With Quote
Old 08-31-2013, 01:24 PM   #2
Houseoffubar
fine beer sampler
 
Houseoffubar's Avatar
 
Joined: Dec 2010
Location: Bothell, Washington
Oddometer: 1,765
Big CC's are the easiest, and most reliable way to make power.
__________________
1978 R100/7 Build thread 1915 Boardtrack racer replica (Electric Powered) Lots of bicycles
Hemp: The strongest natural fiber in the world, and the most nutritious plant on earth.....why is this illegal again?
Houseoffubar is offline   Reply With Quote
Old 08-31-2013, 01:27 PM   #3
walkingbear
Beastly Adventurer
 
walkingbear's Avatar
 
Joined: Jun 2004
Location: Scottsdale AZ..
Oddometer: 3,376
power or torque

When he installed the 1000 cc pistons .. are they high compression pistons from the 70" or the flat head piston from the 80's?

Changing to a high compression piston would add power.
You need torque to pull a side car. I just changed out my R1150GS final drive to on from a R850 (37/11) plenty of power to pass and ride in the highway.
Loss a few mpg but I have a adv tank

I have a R100GS that had the top end ceramic coated. I'm running a R100S piston with R100 GS heads and 32 mm bings. Should have improve HP and better mph. Keeping the final drive the same.

You could go to the 40 mm bings but I think you would lose your low end and mid range but you have your high end passing.
__________________
BMWMOA 82741 ABC 8418
2wheeltraditions@gmail.com
75 R90S , 77 R100 RS,88 R100GS ,94 R1100RS (Aragorn) 2k 1150GS DMC sidecar,
Rosso Mandello V11 , 2014 R nine T
walkingbear is offline   Reply With Quote
Old 08-31-2013, 02:10 PM   #4
Ace_Cafe_Rat OP
Rogue Adventurer
 
Ace_Cafe_Rat's Avatar
 
Joined: Mar 2007
Location: Undisclosed Location in the Nuevo Mexico Desert
Oddometer: 223
More Power....

Thank you both for your replies. It has been about three years since I purchased the bike so I'm afraid I cannot recall positively, but I believe the nikasil(?) cylinders did give a slight bump-up to the compression.

I forgot to mention that another thing Neff Engineering did was to go to a lower ratio in the bike's FD...to one that is the same as the one in an R75/x...to think of it Perry's Sidecars did the same thing when building my R100/7-Ural rig back in 2008.

Ace Cafe Rat
__________________
"Curse your sudden but inevitable betrayal!"

Hoban "Wash" Washburne - Firefly & Serenity

Ace_Cafe_Rat screwed with this post 08-31-2013 at 02:18 PM Reason: Added stuff.
Ace_Cafe_Rat is offline   Reply With Quote
Old 08-31-2013, 04:43 PM   #5
walkingbear
Beastly Adventurer
 
walkingbear's Avatar
 
Joined: Jun 2004
Location: Scottsdale AZ..
Oddometer: 3,376
Quote:
Originally Posted by Ace_Cafe_Rat View Post
Thank you both for your replies. It has been about three years since I purchased the bike so I'm afraid I cannot recall positively, but I believe the nikasil(?) cylinders did give a slight bump-up to the compression.

I forgot to mention that another thing Neff Engineering did was to go to a lower ratio in the bike's FD...to one that is the same as the one in an R75/x...to think of it Perry's Sidecars did the same thing when building my R100/7-Ural rig back in 2008.

Ace Cafe Rat
that would be a 37/11 great to get off the line but your top end is just about 85-90 pushing a tug. I would think your nikasil had the flat top piston which had less compression.
__________________
BMWMOA 82741 ABC 8418
2wheeltraditions@gmail.com
75 R90S , 77 R100 RS,88 R100GS ,94 R1100RS (Aragorn) 2k 1150GS DMC sidecar,
Rosso Mandello V11 , 2014 R nine T
walkingbear is offline   Reply With Quote
Old 08-31-2013, 10:38 PM   #6
Plaka
Brevis illi vita est
 
Joined: Jun 2010
Oddometer: 4,587
Make a choice; do you want power and performance or do you want an airhead? If you're committed to the airhead you are working with 30 year old technology. It was a quieter and gentler time, the national speed limit was 55….

If the R100 isn't getting it, your options are limited, mostly by your wallet. A stock R100, high compression, 38 mm exhaust will get about 70 HP.

Starting with your R80: Spend $2700 for a Sibenrock 1070 kit, $1000 for some big valve R100 heads, a full valve job and dual plug drilling, 200 for some coils and $150 for gaskets and wires and you get about 7-8 more HP than the R100. (the Sibenrock kit advertises HP numbers in line with the R100 .1hp/cc). I bet you get more going with Moteren-Israels kit, they want you heads in their shop for work---gonna cost a lot more too. Anyway you're at 4,050 for maybe 78 HP (at the crank). THEN things start to get expensive.

Go $450 for a pair of r100 nickasil jugs, $400 for new stock 9: 1 pistons, the same $1350 for the heads and etc. and you're at $2,200 for 70 HP. Its cost twice as much for only 8-9HP more!

Rough general consensus is airheads top out at 90 HP…with enough money---and reliability and longevity are compromised.

I looked at some of the DM series sidecars. They get coy with the specs. But looks like mild steel frames and cored 'glasswork. Heavy. 200# and an aerodynamic nightmare. The aeros will hurt you, exponentially, the faster you try to go. And you will suck fuel, so you have to carry more, your weight goes up further…

If you bias your performance for off road work things may look better. If you can hold a steady 65MPH into a light wind you're good. Ride smart---your shadow always points to danger and the longer the shadow, the greater the danger. Conspicuity matters if you are depending on others seeing you for your safety. Kick back, but some Hendix on the 8 track and pound out the miles. The truckers will know all about you miles before they see you, everyone else will slow down to rubberneck the strange what-IS-that-thing.

Here, you would do the R100 high compression dual plug conversion, then go with the low-first-long-fifth tranny mod, with a stock or slightly lower rear end.

Nickasil by itself has little to do with power. Cools better so you can make a bit more heat.

Bigger carbs will hurt your lower and midrange. Build the motor to have good torque there then use your gearing to keep it near the torque band on the highway.

The exhaust doesn't have some big cork in it that you can pull out and get all sorts of performance. I have a very high flow exhaust. It is good for a little---very little. A 2--->1 system will give you a bit better scavenging if it's built right. Maybe half a HP there. Going to 40 MM is also good for something. Last time I talked to the Epco guy he had built some custom stainless 2--->1 sidecar exhausts. They run up the left. Makes it easy to change your oil too. The big gain is in weight savings. Shave 40 LBs right there. Look good.

Getting it lighter will help a lot with climbing hills and passes, and off road. Get 150 lbs off and you get it back near the merely bloated R80g/s. Between the bike, chair, your carry on luggage and your waistline, there are many opportunities. Most of it costs money: light batteries, special tools, etc. --except the waistline where you can save money on food.

Keep an eye on the aeros at speed, particularly parasite drag.
Plaka is offline   Reply With Quote
Old 09-01-2013, 09:44 AM   #7
DaveBall
Beastly Adventurer
 
DaveBall's Avatar
 
Joined: Sep 2009
Location: Vancouver Island
Oddometer: 1,162
What Plaka said -

Putting a sidecar on an Airhead is a great idea, if you are not looking at high speed touring. The two just don't work well.

If you want to be able to do high speeds with a sidecar, you have to make a lot more horsepower and torque. You will need a much more modern engine, frame, etc. Or, just install a VW engine and hop it up. I have seen some done that can cruise at very high speeds, but I wouldn't want to do it. High power in an Airhead rubber cow frame attached to a heavy sidecar is just asking for trouble.
DaveBall is offline   Reply With Quote
Old 09-01-2013, 11:54 AM   #8
Ace_Cafe_Rat OP
Rogue Adventurer
 
Ace_Cafe_Rat's Avatar
 
Joined: Mar 2007
Location: Undisclosed Location in the Nuevo Mexico Desert
Oddometer: 223
Doh!

Quote:
Originally Posted by Plaka View Post
Make a choice; do you want power and performance or do you want an airhead? If you're committed to the airhead you are working with 30 year old technology. It was a quieter and gentler time, the national speed limit was 55...Starting with your R80: Spend $2700 for a Sibenrock 1070 kit, $1000 for some big valve R100 heads, a full valve job and dual plug drilling, 200 for some coils and $150 for gaskets and wires and you get about 7-8 more HP than the R100. (the Sibenrock kit advertises HP numbers in line with the R100 .1hp/cc). I bet you get more going with Moteren-Israels kit, they want you heads in their shop for work---gonna cost a lot more too. Anyway you're at 4,050 for maybe 78 HP (at the crank). THEN things start to get expensive...Getting it lighter will help a lot with climbing hills and passes, and off road. Get 150 lbs off and you get it back near the merely bloated R80g/s. Between the bike, chair, your carry on luggage and your waistline, there are many opportunities. Most of it costs money: light batteries, special tools, etc. --except the waistline where you can save money on food.Keep an eye on the aeros at speed, particularly parasite drag.
Plaka,

Wow! I REALLY appreciate you taking the time to share so much experience and knowledge with this relatively noob Airhead owner. Cold counsel is the most valuable and the hardest to obtain. Thank you for yours. You have saved me a boatload of money and time trying to make an Airhead engine into something it was never intended to be. Dang it! :-)

Ace Cafe Rat
__________________
"Curse your sudden but inevitable betrayal!"

Hoban "Wash" Washburne - Firefly & Serenity

Ace_Cafe_Rat screwed with this post 09-01-2013 at 11:55 AM Reason: Rewording.
Ace_Cafe_Rat is offline   Reply With Quote
Old 09-01-2013, 12:01 PM   #9
Ace_Cafe_Rat OP
Rogue Adventurer
 
Ace_Cafe_Rat's Avatar
 
Joined: Mar 2007
Location: Undisclosed Location in the Nuevo Mexico Desert
Oddometer: 223
Doh2!

Quote:
Originally Posted by DaveBall View Post
What Plaka said - Putting a sidecar on an Airhead is a great idea, if you are not looking at high speed touring. The two just don't work well. If you want to be able to do high speeds with a sidecar, you have to make a lot more horsepower and torque. You will need a much more modern engine, frame, etc. Or, just install a VW engine and hop it up. I have seen some done that can cruise at very high speeds, but I wouldn't want to do it. High power in an Airhead rubber cow frame attached to a heavy sidecar is just asking for trouble.
Thanks! Those are all good points. Dang it.

I wonder if a carb Oilhead engine would even fit in the R80ST's frame? I think have seen a pic of one in this web forum that IIRC was fitted into what appeared to be a /2 frame.

Ace Cafe Rat
__________________
"Curse your sudden but inevitable betrayal!"

Hoban "Wash" Washburne - Firefly & Serenity
Ace_Cafe_Rat is offline   Reply With Quote
Old 09-01-2013, 02:20 PM   #10
walkingbear
Beastly Adventurer
 
walkingbear's Avatar
 
Joined: Jun 2004
Location: Scottsdale AZ..
Oddometer: 3,376
what is your goal

Kind of wonder what is your vision for this R80/100ST/GS

Are you going to reinforce the frame?
__________________
BMWMOA 82741 ABC 8418
2wheeltraditions@gmail.com
75 R90S , 77 R100 RS,88 R100GS ,94 R1100RS (Aragorn) 2k 1150GS DMC sidecar,
Rosso Mandello V11 , 2014 R nine T
walkingbear is offline   Reply With Quote
Old 09-02-2013, 09:58 AM   #11
Ace_Cafe_Rat OP
Rogue Adventurer
 
Ace_Cafe_Rat's Avatar
 
Joined: Mar 2007
Location: Undisclosed Location in the Nuevo Mexico Desert
Oddometer: 223
Plans for My New Rig? (A R80ST-based Airhead)

Quote:
Originally Posted by walkingbear View Post
Kind of wonder what is your vision for this R80/100ST/GS. Are you going to reinforce the frame?
The overarching goal is to have a rig capable of taking me anywhere in the Southwest and back again. Since moving from Madison, WI back in early 2003 to the Greater ABQ area in NM I have learned the joy of the unpaved roads. Unfortunately to reach most of them I have to endure miles of Interstate Highways with as Speed Limit of 75 MPH...which means most folks are going 80 MPH at least. On its best day my current R100/7-Ural sidecar sidecar will go 85 MPH on the flat desert floor, but it greatly prefers 65 MPH. I figure the R80ST-DMC rig with its current 1000cc jugs will be no faster. I was after a rig that was faster than a Ural sidehack rig and I have that I am sure.

Lowell Neff Engineering has already modified-strenghted the swingarm to fit a car tire on the bike and installed a new heavier monoshock. But IIRC all of the Airhead frames are rather "flexible" so adding some addition power will probably reveal the need for additional bracing. Especially if I fit an Oilhead engine in it. Like this one someone created http://www.bmwra.org/forum/showthrea...-Old-meets-New

All Advice is Welcome!

Ace Cafe Rat
__________________
"Curse your sudden but inevitable betrayal!"

Hoban "Wash" Washburne - Firefly & Serenity

Ace_Cafe_Rat screwed with this post 09-02-2013 at 07:11 PM Reason: Added Link. Corrected mistakes.
Ace_Cafe_Rat is offline   Reply With Quote
Old 09-02-2013, 10:28 AM   #12
R100LT
Chasing 11
 
R100LT's Avatar
 
Joined: Jan 2012
Location: Donnybrook Western Australia
Oddometer: 626
Don't give up so quickly ... We like spending other people's money
__________________
BMW R100LT 93 BMW R100RS 91 BMW K1100LT SE 94 76 R90S
R100LT is offline   Reply With Quote
Old 09-02-2013, 12:44 PM   #13
walkingbear
Beastly Adventurer
 
walkingbear's Avatar
 
Joined: Jun 2004
Location: Scottsdale AZ..
Oddometer: 3,376
suggestion

think about a R1100GS or R850 R .. pretty reliable and will easily pull that car. The R850 has a 37/11 rear drive. I just mounted the same drive to my R1150gs. It pulls nicely



You can take a R1100GS and put carbs on them and take the abs out.
Now you have a nice ride
__________________
BMWMOA 82741 ABC 8418
2wheeltraditions@gmail.com
75 R90S , 77 R100 RS,88 R100GS ,94 R1100RS (Aragorn) 2k 1150GS DMC sidecar,
Rosso Mandello V11 , 2014 R nine T
walkingbear is offline   Reply With Quote
Old 09-02-2013, 02:42 PM   #14
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,660
More CC's than 980? The factory stopped there for MANY good reasons!

Did your 800cc heads have the combustion chamber enlarged? Did it get the 'kit' Siebenrock pistons for such an occasion?

You already have the best clutch/flywheel setup, now you need a 336 and some 38mm Dellorto carbs. That's your biggest, completely reliable, way more low rpm pulling power torque getters for the money. I would probably raise CR and dual plug at the same time for even more all good from all revs. Clean up the ports some and 44mm intake valves would help too. All of those modes are just as reliable as stock but with way more low, mid and high rpm power.

38mm Dells or Mikuni's will get you way more low end than 32mm Bings AND way more top end. Compared to 32mm Bings? Bigger carbs will HELP your low rpm performance! That is except for 40mm Bings.

3.37:1 FD? you should still be able to pull 115mph IF you modify it to get more power.

I wouldn't run a 1070 kit. 980 is a big as that engine can handle long term.

I wouldn't follow the typical advise of looking for some big port/valve heads. The small port heads breath better IMO and can easily get the same 44mm intakes of a big port/valve head. The best of two worlds in a lot of eyes. They just aren't as googleable.

supershaft screwed with this post 09-02-2013 at 03:21 PM
supershaft is offline   Reply With Quote
Old 09-02-2013, 02:45 PM   #15
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,660
Quote:
Originally Posted by Plaka View Post
Make a choice; do you want power and performance or do you want an airhead? If you're committed to the airhead you are working with 30 year old technology. It was a quieter and gentler time, the national speed limit was 55….

If the R100 isn't getting it, your options are limited, mostly by your wallet. A stock R100, high compression, 38 mm exhaust will get about 70 HP.

Starting with your R80: Spend $2700 for a Sibenrock 1070 kit, $1000 for some big valve R100 heads, a full valve job and dual plug drilling, 200 for some coils and $150 for gaskets and wires and you get about 7-8 more HP than the R100. (the Sibenrock kit advertises HP numbers in line with the R100 .1hp/cc). I bet you get more going with Moteren-Israels kit, they want you heads in their shop for work---gonna cost a lot more too. Anyway you're at 4,050 for maybe 78 HP (at the crank). THEN things start to get expensive.

Go $450 for a pair of r100 nickasil jugs, $400 for new stock 9: 1 pistons, the same $1350 for the heads and etc. and you're at $2,200 for 70 HP. Its cost twice as much for only 8-9HP more!

Rough general consensus is airheads top out at 90 HP…with enough money---and reliability and longevity are compromised.

I looked at some of the DM series sidecars. They get coy with the specs. But looks like mild steel frames and cored 'glasswork. Heavy. 200# and an aerodynamic nightmare. The aeros will hurt you, exponentially, the faster you try to go. And you will suck fuel, so you have to carry more, your weight goes up further…

If you bias your performance for off road work things may look better. If you can hold a steady 65MPH into a light wind you're good. Ride smart---your shadow always points to danger and the longer the shadow, the greater the danger. Conspicuity matters if you are depending on others seeing you for your safety. Kick back, but some Hendix on the 8 track and pound out the miles. The truckers will know all about you miles before they see you, everyone else will slow down to rubberneck the strange what-IS-that-thing.

Here, you would do the R100 high compression dual plug conversion, then go with the low-first-long-fifth tranny mod, with a stock or slightly lower rear end.

Nickasil by itself has little to do with power. Cools better so you can make a bit more heat.

Bigger carbs will hurt your lower and midrange. Build the motor to have good torque there then use your gearing to keep it near the torque band on the highway.

The exhaust doesn't have some big cork in it that you can pull out and get all sorts of performance. I have a very high flow exhaust. It is good for a little---very little. A 2--->1 system will give you a bit better scavenging if it's built right. Maybe half a HP there. Going to 40 MM is also good for something. Last time I talked to the Epco guy he had built some custom stainless 2--->1 sidecar exhausts. They run up the left. Makes it easy to change your oil too. The big gain is in weight savings. Shave 40 LBs right there. Look good.

Getting it lighter will help a lot with climbing hills and passes, and off road. Get 150 lbs off and you get it back near the merely bloated R80g/s. Between the bike, chair, your carry on luggage and your waistline, there are many opportunities. Most of it costs money: light batteries, special tools, etc. --except the waistline where you can save money on food.

Keep an eye on the aeros at speed, particularly parasite drag.


You can google a whole lot of this misinformation. It's like a rash all over the idiotnet but that doesn't make a lot of it right.
supershaft 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 04:09 PM.


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