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Old 09-03-2013, 09:16 AM   #31
disston
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I said 36mm carb kit. I was thinking of the Rocky Point Cycles kit that is 34mm.

http://www.rockypointcycle.com/p-bmw...kits-2102.html

You should know which size piston and cam shaft you are going to use before ordering the carbs because they will jet them for you which will be a big help. If your final design is too far away from normal set ups you will still have to play with jets to get it right but at least you won't be that far off, hopefully.
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Old 09-03-2013, 10:59 AM   #32
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Originally Posted by Plaka View Post
Unfortunately the power the cam makes is on the high end, not the low. The Bing has it over the Mikuni for mileage. How much juice you wanna carry? The Mikuni is more responsive, the Bing takes more abuse, is simpler to service, eats up crappy gas...
I guess you are talking about a 336? That is simply NOT TRUE.

Bings do not get better mileage than Mikuni's. Mikuni's get better mileage than Bings. Nothing else said above makes any sense from my experience. Have you any experience with what you are talking about? It does not sound like it.
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Old 09-03-2013, 11:14 AM   #33
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I'm not an Airhead expert by any means, but I know a lot of things about a lot of things. I've learned, through wasting tons of money, sweat, tears, frustration and antacids that sometimes the more expensive option is cheaper.

I'd sit down and really crunch some numbers, because I wonder how close in price you'd be to a more modern GS rig once you drop serious loot trying to make this into something it's just not (and shouldn't be - different strokes and all that!).

I love my Beemer, but the engine produced 70 horsepower new and the frame was designed 45 years ago. I can make it go faster and handle better, but I'll never play hide-and-seek in the canyons with a new GSXR750. Just the wrong tool for the job.
70 hp? BMW hp? My airhead engine is very reliably modified to 95 'BMW' hp. I love it. I have left literally hundreds of new GSXR's behind in the canyons. Granted, I do think starting with a later model like my Monolever airhead helps. That's why I have one but . . . . The real trick is to focus on your riding WAY before you start thinking about bikes. I would honestly guess that around 199 out of every 200 GSXR riders don't even know the beginning of riding well. You don't need the right tool for that. Besides, it's a lot more fun!
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Old 09-03-2013, 11:51 AM   #34
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Originally Posted by supershaft View Post
70 hp? BMW hp? My airhead engine is very reliably modified to 95 'BMW' hp. I love it. I have left literally hundreds of new GSXR's behind in the canyons. Granted, I do think starting with a later model like my Monolever airhead helps. That's why I have one but . . . . The real trick is to focus on your riding WAY before you start thinking about bikes. I would honestly guess that around 199 out of every 200 GSXR riders don't even know the beginning of riding well. You don't need the right tool for that. Besides, it's a lot more fun!
It's a '78 R100S engine with supposedly 25k, 70 was the factory number and we all know German engineers never lie . It's a hoot to ride, and it's got more than enough power for me everywhere in the rev range. I don't doubt that somebody with more skill and good rubber could chase around someone on a hell of a lot more bike and keep up. And I'm all for modifying what ya got into what ya want... but if I had $10k to spend to turn mine into a 350lbs. dry and 100hp flickable backroad monster, I'd figure I came out ahead turning that $10k into a CBR600 and enjoying the Beemer for the big torquey clattering mechanical indestructible thing it is. It's as much fun in the canyons as those crazy sportbike kids anyway, just slower. Besides, the nearest canyon is half the country away - my bike can get me there and back with giving me calluses on my ass.

And I agree that not many users of performance machinery ever get anywhere near it's limits. I drive a Mazdaspeed6, which ultimately is a big 4 door sedan with AWD, a turbo, suspension tuning, and wide tires. It's a fun car, but no extreme performance exotic by any means. I've never even made it break a sweat. Not even nervous. I can't imagine how bored to death those poor Ferraris and Bugattis the old men idle up and down the Viagra Triangle (a Chicago area known for facilitating Gold Digger/Sugar Daddy interaction) must be.

So anyway, back to the question at hand. I just figure when looking at cold hard numbers, that when you're looking to turn Thing X into Thing Y, price out the modifications and then shop around for local low-mileage well maintained Thing Y in good nick. See where they balance out.
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Old 09-03-2013, 12:27 PM   #35
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I'll race ya. I have a 4.6 Ford, 4 doors, Automatic, PosiTraction 3.55 gear. Crown Victoria, Police Interceptor.
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Old 09-03-2013, 12:54 PM   #36
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Originally Posted by CaptainCrunch View Post
It's a '78 R100S engine with supposedly 25k, 70 was the factory number and we all know German engineers never lie . It's a hoot to ride, and it's got more than enough power for me everywhere in the rev range. I don't doubt that somebody with more skill and good rubber could chase around someone on a hell of a lot more bike and keep up. And I'm all for modifying what ya got into what ya want... but if I had $10k to spend to turn mine into a 350lbs. dry and 100hp flickable backroad monster, I'd figure I came out ahead turning that $10k into a CBR600 and enjoying the Beemer for the big torquey clattering mechanical indestructible thing it is. It's as much fun in the canyons as those crazy sportbike kids anyway, just slower. Besides, the nearest canyon is half the country away - my bike can get me there and back with giving me calluses on my ass.

And I agree that not many users of performance machinery ever get anywhere near it's limits. I drive a Mazdaspeed6, which ultimately is a big 4 door sedan with AWD, a turbo, suspension tuning, and wide tires. It's a fun car, but no extreme performance exotic by any means. I've never even made it break a sweat. Not even nervous. I can't imagine how bored to death those poor Ferraris and Bugattis the old men idle up and down the Viagra Triangle (a Chicago area known for facilitating Gold Digger/Sugar Daddy interaction) must be.

So anyway, back to the question at hand. I just figure when looking at cold hard numbers, that when you're looking to turn Thing X into Thing Y, price out the modifications and then shop around for local low-mileage well maintained Thing Y in good nick. See where they balance out.
$10,000? About the only money I have spent on my bike other than things I would have had to spend on it stock or not is having my heads milled and dual plugged. My cam? I needed one anyway. Carbs? I got those for free. I did my port job. My Fox shock? I needed one and it was on sale. My titanium valve spring retainers? That was a bit of extra money too but we are still under $1000.

Big torquey clattering indestructible thing it is? Mine never clattered near as much as most for setting my valve clearance and rocker arm end play correctly. Torquey? Mine now has way more torque than it ever did and has been every bit as reliable in the last 75,000 miles.

Comfort? It is the exact same bike it ever was in that regard excepting that now it vibrates less.

CBR600? Keeping tires on one would cost me a lot more than my modified airhead. Fat tires are big money.
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Old 09-03-2013, 01:40 PM   #37
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Quote:
Originally Posted by supershaft View Post
$10,000? About the only money I have spent on my bike other than things I would have had to spend on it stock or not is having my heads milled and dual plugged. My cam? I needed one anyway. Carbs? I got those for free. I did my port job. My Fox shock? I needed one and it was on sale. My titanium valve spring retainers? That was a bit of extra money too but we are still under $1000.

Big torquey clattering indestructible thing it is? Mine never clattered near as much as most for setting my valve clearance and rocker arm end play correctly. Torquey? Mine now has way more torque than it ever did and has been every bit as reliable in the last 75,000 miles.

Comfort? It is the exact same bike it ever was in that regard excepting that now it vibrates less.

CBR600? Keeping tires on one would cost me a lot more than my modified airhead. Fat tires are big money.
Hey, I paid EXTRA for that clatter, buddy!
It's just how it lets me know it's not a sewing machine like the car.

And $10k was an arbitrary number. There's a dozen CBR's on local CL for under $3k, couple that need work around $2k. Not everybody is mechanically apt, either. Some guys have the will but don't have a garage/shop. I'm sure somebody out there is a golden god who could have cast new jugs and titanium valves using a scrollsaw and a stump - there's always somebody who could have done a job cheaper, and there's always a way to spend more money on something. For me personally, I don't want to modify something if I don't have to - I hate having my stuff torn apart any longer than necessary. Can't ride it in pieces and drives me bonkers.

All I'm saying is, when you need a tool for a certain job, check out the prices for that exact tool before taking a welder and a grinder to one you already have. It might be better suited to the job, and then you'll have both.

I also try and stockpile excuses to buy more motorcycles. That's very important.
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Old 09-03-2013, 01:43 PM   #38
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Originally Posted by Ace_Cafe_Rat View Post
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!

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Sidecars are just about the only useful argument I can think of for an Oilhead BMW. Seriously.

If you've already had an R100/7 Ural combo, you basically know what you're going to be in for with the R80/100G/S rig. Upping the game would be very much simpler, cheaper and more successful with an R1100 or R1150. They've got more power, torque, brakes, chassis rigidity and that retarded BMW Tele-Lever front end which would actually work pretty good on a sidecar tug.

imho, fwiw, ymmv,
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Old 09-03-2013, 01:57 PM   #39
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Sidecars are just about the only useful argument I can think of for an Oilhead BMW. Seriously.

If you've already had an R100/7 Ural combo, you basically know what you're going to be in for with the R80/100G/S rig. Upping the game would be very much simpler, cheaper and more successful with an R1100 or R1150. They've got more power, torque, brakes, chassis rigidity and that retarded BMW Tele-Lever front end which would actually work pretty good on a sidecar tug.

imho, fwiw, ymmv,
Lornce

I have a 1150GS sidecar rig...and compared to an airhead car..there is miles of difference. I have a 37/11 rear off a R850 and just pulls and keeps pace on the highway.

I'm looking to build an adventure sidecar rig next with a R100GS but it will be just for supplies not a rider. Won't weight as much.

Putting too many $$ for a project could be /would be a waste of $$$ for other projects.
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Old 09-03-2013, 02:17 PM   #40
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I have 7 Airheads including a 1070 R100GSPD, I also have a sidecar with a K100RT as a Tug, in my view an Airhead on a sidecar does not work for Freeway riding, much cheaper with a K bike, being watercooled and a bullet proof engine they are a much better choice, cheaper in the long run too.

A 1070 engine loves to rev, a sidecar needs low down torque.
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Old 09-03-2013, 09:06 PM   #41
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I have a 1150GS sidecar rig...and compared to an airhead car..there is miles of difference. I have a 37/11 rear off a R850 and just pulls and keeps pace on the highway.

I'm looking to build an adventure sidecar rig next with a R100GS but it will be just for supplies not a rider. Won't weight as much.

Putting too many $$ for a project could be /would be a waste of $$$ for other projects.
Actually my new rig will be used in the very way -- the sidecar itself being a giant pannier on a wheel. DMC built it with a lockable hardtop that can be completely removed to carry a passenger at need.

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Old 09-03-2013, 09:10 PM   #42
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Actually my new rig will be used in the very way -- the sidecar itself being a giant pannier on a wheel. DMC built it with a lockable hardtop that can be completely removed to carry a passenger at need.

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Nitrous. Just for the hills.
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Old 09-03-2013, 09:25 PM   #43
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Nitrous. Just for the hills.
Yeah. How come we never think of Nitrous? Would be perfect for what the Rat wants. Build a moderately hot Airhead sidecar and when going up some steep hill hit "the button". A sidecar would be perfect because you could hide the bottle. They are also not very expensive.
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Old 09-04-2013, 08:20 AM   #44
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Yeah. How come we never think of Nitrous? Would be perfect for what the Rat wants. Build a moderately hot Airhead sidecar and when going up some steep hill hit "the button". A sidecar would be perfect because you could hide the bottle. They are also not very expensive.
We never think of nitrous because an aircooled motor would be hard pressed to handle the heat. Nitrous, water injection and dead loss water cooling, maybe.

I'm working on a dead loss water cooling system. The physics looks good. The engineering remains to be seen.
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Old 09-04-2013, 09:17 AM   #45
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Yeah. How come we never think of Nitrous? Would be perfect for what the Rat wants. Build a moderately hot Airhead sidecar and when going up some steep hill hit "the button". A sidecar would be perfect because you could hide the bottle. They are also not very expensive.
Nitrous? Why not just mount one of those rockets that aid carrier jets in taking off from their flattop?

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