Single Carb Airhead

[caponerd]

Originally Posted by crazydrummerdude

So, in the opposite mindset, should I put multiple carbs on my BMVW? It has one carb and four cylinders.

Well, the hot setup on the old 2002 BMW cars was four Weber side draft carbs, so why not?
You could at least a single dual throat carb on each side. I'm pretty sure they make hardware for that kind of setup on a VW engine.

Err, just notice in another thread...

[SOLO LOBO]

Originally Posted by Smallwheelsgood

I have heard that carb icing may occur with such long inlet tracts, other than that I envisage that it would offer less complication and maintenance, and perfect balance with only a small reduction in top end performance. Any help would be much appreciated.

I'd say to look to history. When Ducati installed a single Weber (I think) on their late 1980's/early 1990's SS series the results were not good, and many owners went back to two carbs.

Setting up seperate carbs to work well can take a few minutes, but holds well between valve adjustements or longer. If you are concerned about the time it takes to keep a bike running well, perhaps an airhead is not the bike for you.

[Smallwheelsgood]

Ok, thanks to all. What about supercharging then? I know about the factory racer, but has it been achieved by anybody else since?

[marksbonneville]

Originally Posted by Smallwheelsgood

Ok, thanks to all. What about supercharging then? I know about the factory racer, but has it been achieved by anybody else since?

Seriously why not consider mechanical fuel injection if complexity is the goal. BTW what is the goal?

[Smallwheelsgood]

OK, thanks to all, sounds like a dead end. So what about supercharging an airhead? I'm aware of the factory racer, but has anybody else achieved this since?

[Smallwheelsgood]

Originally Posted by marksbonneville

Seriously why not consider mechanical fuel injection if complexity is the goal. BTW what is the goal?

The goal concerning the single carb was simplicity. As far as the above is concerned, just curiosity.

[Hawk Medicine]

Originally Posted by marksbonneville

Seriously why not consider mechanical fuel injection if complexity is the goal. BTW what is the goal?

Thats another item that has been successfully applied to Airheads. Once again, there were several people who transplanted VW injector systems into Airheads in the late 80's/early 90's.

I would think that it would be much easier today but that stuff is over my head. I'm doing well to take care of what I have!

[Houseoffubar]

Now your talking!
I don't think it would be easy, but supercharging would be a good way to get some healthy power out of an Airhead. Turbocharging works, but is not the best way to go with a twin.
I would look into an intercooler, and water/alcohol injection as Airheads are already detonation prone already.
Now you just have to figure where to mount it, and how to drive it!

[marksbonneville]

Originally Posted by Smallwheelsgood

The goal concerning the single carb was simplicity. As far as the above is concerned, just curiosity.

OK gotcha, well the stock cv carb is pretty simple but I see where you are going. I had a Judson Super Charger on my VW for a while, did not gain much power but it looked cool.

[Grider Pirate]

Originally Posted by Smallwheelsgood

Hello all, newbie to this site, I have lurked for a while and have found a wealth of information and experience, plus some cracking pictures.
I have 2 no. R100RS's, 1 x 1978 in bits, 1 x 1983 running reasonably well. I have long wondered about converting to a single carb setup, does anyone know of this ever having being done? If not, what would be the pros and cons of such a setup. I have heard that carb icing may occur with such long inlet tracts, other than that I envisage that it would offer less complication and maintenance, and perfect balance with only a small reduction in top end performance. Any help would be much appreciated.

I have been curious about this for some time. I have two airheads that are running perfectly well, so maybe it's time to 'break' one of them. It turns out that one of the guys in my glider club has a dyno, so some figures would be available. I would expect, and accept, some loss of power. The icing issue was truly significant on the old VW's, and would likely also be a big issue on the airhead. I think it might be easier to feed warmed air to the air filter box (like aircraft)than to do it like a VW.

[drhach]

Originally Posted by marksbonneville

Seriously why not consider mechanical fuel injection if complexity is the goal. BTW what is the goal?

Less moving parts, less wear items, EFI seems simpler to me.

[marksbonneville]

Originally Posted by drhach

Less moving parts, less wear items, EFI seems simpler to me.

Well that would make sense and if we are going to be sensible then leaving the stock CV's would be the best option. I was just tossing out a really complicated idea that would cost a lot of $$ and make little power, kind of like adapting a single carb.

[wirewrkr]

Originally Posted by mymindsok

Thats another item that has been successfully applied to Airheads. Once again, there were several people who transplanted VW injector systems into Airheads in the late 80's/early 90's.

I would think that it would be much easier today but that stuff is over my head. I'm doing well to take care of what I have!

Yeah, they call it a K bike.
Same basic system as the aircooled VWs

[Lornce]

Originally Posted by Tosh Togo

And you'd get a lot of questions beginning with "WTF were you thinking?."

Great thread.

[lkchris]

Originally Posted by kadesean

If you are talented enough to pull off this mod you have to be talented enough to balance your carbs every 5-10,000 miles.

Very true ... but if you convert to the one-into-two throttle cables, that will be the last time the carbs need balancing until they're removed for rebuilding.