Fuel injection for an airhead!

[DSBMW1]

Silent Hektik has a fuel injector upgrade for airheads. Does anyone know anything more about this? Does anyone else think this is a great idea?

[jdmetzger]

Silent Hektik has a fuel injector upgrade for airheads. Does anyone know anything more about this? Does anyone else think this is a great idea?

I don't think it's a good idea.

I think it ruins the "simplicity" of the airhead. It replaces two very simple (but effective) fuel/air mix/metering devices (carbs) and replaces them with a bunch of fancy parts and a computer, and substantially lightens your wallet.

The carbs work, and have many years and millions of miles of testing. They're also not prone to a sudden failure. Sure, your float bowl could develop a leak in the middle of Africa, but all you need is some gasket maker or some flat cork and a knife to make a temporary repair. (making a float gasket with cork and a knife CAN be done, DAMHIK). Your diaphragm might get a tear, but you can fix that with some glue. Generally, a "failure" with a carb is a buildup of resins and crud until you need to rebuild it. You get plenty of warning with that. On the other hand, if the computer fails on that injection system in the middle of nowhere, you'll be walking/calling for help... if there is any. Sure, you might get a little better mileage or power (I can't find info on test results, right now), but I think the small pluses outweigh the minuses.

[cjack]

Silent Hektik has a fuel injector upgrade for airheads. Does anyone know anything more about this? Does anyone else think this is a great idea?

I think it's a wonderful idea. BMW did it. I wonder if one could stuff an oilhead engine into a /2...heh.

[Ridealot]

And the purpose of throwing a huge amount of money and time to put fuel injection on an Airhead would be what ???? :dunno

[easter85]

Ditto!

Now a really good "normalizer" would be worth it. "Normalizer" in light aircraft is a turbo set up that just gives just enough boost to maintain sea level power as you gain altitude. Now that is something I would like on my /7 and probably wouldn't be to hard on the engine.

[Motor31]

A fuel injected airhead would simply be a weak oilhead. Why bother spending the money to do that. If you want an oilhead get one and leave the airhead to someone who would appreciate it's qualities as is.

[dlearl476]

Silent Hektik has a fuel injector upgrade for airheads. Does anyone know anything more about this? Does anyone else think this is a great idea?

Airheads had injectors?

Oh, you mean a fuel injection CONVERSION.

If you had the mechanical aptitude, I would think it would be a relatively easy process to adapt a throttle body/injector set up to an airhead. But I doubt you'd get much out of it other than the satisfaction of having done it.

[Boxerkuh]

I would not do it. Fuel Injectors and computers only make our life on the Airhead more complicated. If a fuel injection is what you want just buy an oilhead. Probably much more efficient and cheaper than if you do it yourself, plus you get a warranty with it....

[osbornk]

I keep my airhead and 62 Ford Fairlane because I'm a KISS kind of person. However, I also like newfangled gadgets and that is why I bought an oilhead and the new style F-150. I don't like to mix new and old and I confuse even myself.

[rinty]

There would be two potential upsides to a reliable fuel injection system for airheads: improved starting, and improved throttle response. Luftmeister made a kit some years ago, but I have never seen one on any bike.

This might be a fun project for an airhead enthusiast who has the means and the patience to see it through.

Rinty

[dlearl476]

Did the "classic edition" R100RT re-issue have FI or is my mind playing tricks on me?

[manicmechanic]

I am reminded of seeing an Oilhead at a rally this summer that had been converted to carbs. He said he had it almost right.

[jbcollier]

No airheads had fuel injection from the factory. CV carbs are pretty darn efficient if they are jetted properly.

[Bobmws]

Many years ago, 15?, either Luftmeister or CCProducts had a FI kit for airheads. One fellow up in N.Georgia spent lots of effort and $$ installing them on an R80ST, along with a K-bike front end and many other performance improvements.
He was one of the first to buy an Oilhead, saying that it was everything he had been trying to make his Airhead into.

Now Cjack, an oilhead in a /2? That would be interesting!

[rinty]

We can probably imagine how well those Luftie fuel injection kits worked.

Rinty

[PeoriaMac]

[QUOTE=rinty]We can probably imagine how well those Luftie fuel injection kits worked.

Many many years ago, there was a guy with an R65 in the Chicago area who'd added a Luftmeister trubo to his bike. It required windshield washer fluid added to the mix, somehow. Any old-timers from the Windy City remember this bike...or rider...or both??

Mac

[rinty]

A friend of mine, who is a good wrench, had the turbo kit on an RS, but the heads slowly disintegrated. The motor just wasn't up to it.

There must be some fuel injection stuff over at the airheads site. I'll have a look when I get home from Saskatchewan and back to a fast computer.

If I can get through this snow today......

Rinty

[Isamemon]

Im an old fart to some people, so take this wiht a grain of salt
to me one of the Beautiful things about my old airhead is easy repairs.
now I know I do live in a rural area so this may be different for you
but resetting points, or ( like recently) unsticking a float on the side of the road, in the middle of bumb frick no place, in the snow, is a real advantage.
a computer crap out or something, 20 miles from the nearest home, is not apealing to me :sick
even if it got me a few miles to the gallon or cut a half second off my 1/4 mile time
to me. its not more speed or mpg that this old scooter needs, its BRAKES

[vanzen]

fuel injection's biggest advantage relative to a Type 247 BMW:
cleaner emissions &, if programmed efficiently / precisely, perhaps a smidgeon of performance – after idle, and before WOT.

[CraigC]

Any old-timers from the Windy City remember this bike...or rider...or both??


I believe that was John from All Brand Motorworks (at Addison & California) that had the turbo R65. Until last year he had a K75 turbo (now sold) and a 1978 R100RS with turbo & nitrous. The turbo & nitrous has been removed from the RS and he had the bike for sale at his shop last time I was there.

[lkchris]

fuel injection's biggest advantage relative to a Type 247 BMW: cleaner emissions &, if programmed efficiently / precisely, perhaps a smidgeon of performance – after idle, and before WOT.

Mostly overstated IMHO.

The Bing carb--being a constant velocity design with no accelerator pump--does a very good job of giving your engine what it needs, with hardly any overrich episodes.

The intake tract of an Airhead is very short and there's obviously one carb per cylinder--both of which match most of the advantages of fuel injection. The cylinders of Airheads are QUITE evenly filled.

A gasoline engine MUST run on the 15:1 air/fuel ratio and nothing about installing fuel injection increases the amount of air ingested by the engine, meaning the fuel injection will then inject the same amount of fuel the Bing provides, meaning performance will be exactly the same.

Biggest advantage of fuel injection is that it's more reliable and requires less maintenance--meaning your engine will stay in tune longer. Another advantage is that there's very little for the shade tree idiot to change and inevitably mess up.

FI is also potentially cheaper, as an injector certainly doesn't cost as much as a carburetor. When you get to four cylinders--like a K--cost of fuel pump and CPU and wire harness may not exceed that of four carbs. Don't think you can manufacture a carburetor with robots.

[Motor31]

If you want to increase power with an airhead you'd be better off getting the heads ported and polished so they flow better add high compression pistons then set the carbs accordingly. At that point you might gain a little bit more by adding a second plug since you already have the heads off anyhow.

[rinty]

Manley:

Prior to your post I wasn't aware of Silent Hektik, but on the web site, their stuff certainly looks to be of high quality.

The fuel injection kit looks super interesting, but the challenge would be to find an airhead genius willing to trouble shoot the inevitable "dial - in" issues, after installation. Maybe S H have someone over here who has already installed one.

If you could somehow pull if off, an injected airhead would certainly be an attention getter at any airhead meet.

Rinty

[28796]

A gasoline engine MUST run on the 15:1 air/fuel ratio and nothing about installing fuel injection increases the amount of air ingested by the engine, meaning the fuel injection will then inject the same amount of fuel the Bing provides, meaning performance will be exactly the same.

Biggest advantage of fuel injection is that it's more reliable and requires less maintenance--meaning your engine will stay in tune longer. Another advantage is that there's very little for the shade tree idiot to change and inevitably mess up.


Actually if you are tuning for performance you will end up between 13:1 & 14:1. Modern fuel injection systems allow you to fine tune with different chips or fuel maps to better match the mods you make to the bike with the aid of a dyno.

[PGlaves]

I don't want to start an argument, but I think the CV carbs are over rated in some of these comments. Why did BMW use the D'Lorto pumper on the R90S?

If everything is new out of the box crisp on a CV carb it is OK. But a little bit of varnish or crud in the vacumn ports, a too stiff or too mushy diaphramn, a worn needle or needle jet, a worn slide, or bits of varnish or gum on the main jet or needle jet and the mixture stops being even as good as approximately right.

CC Products, Leuftmeister, and others used to make a bundle with a dyno and exhaust gas analyzer setup at the National rallies dialing in CV carbs with jetting changes. Very often they tried smaller jets, then wound up with stock new jets to compensate for the old worn ones they pulled out.

CV carbs are better than the one which had a steel needle poked by hand through a real cork on my Puch moped, but not a whole lot better.

Since the Silent Hektic injection system runs about $2,000 USD I doubt I would buy it for an Airhead, but that doesn't mean that carbs are better - just that they are cheaper and already on the bike.

IMHO - YMMV

[rinty]

When I had my airhead, my major issue with the Bings was the lack of an accelerator pump to help with cold starts. Even though my bike was in good tune, inevitably I thought I would end up at a high altitude campsite at some time, and the bike would cold soak overnight at sub freezing temperatures. With the 20W - 50 oil now reduced to the thickness of molasses, I am confronted with the morning start, and the engine won't turn over fast enough to create enough vacuum to lift the slides a bit and get enough mixture into the combustion chambers so that the little fires can begin. With a pumper carb, you can (in theory, at least) twist the throttle a few times to pump some fuel into the cylinders.

But with the introduction of AGM batteries, this is no longer a problem, because you can crank the engine over until the cows come home.

If I still had a 1000 cc airhead, I would install 38 mm Mikuni flatslides, for their improved throttle response, and because they look cool.

But installing a fuel injection kit would be an interesting project for someone with deep pockets and lots of patience. And for all we know, the Silent Hektic injectors might be of the constant injection type, like in the old Bosch K - Jetronic systems, and therefore not that complicated.

Rinty

[28796]

I don't want to start an argument, but I think the CV carbs are over rated in some of these comments. Why did BMW use the D'Lorto pumper on the R90S?


While I am no fan of the Bings I believe the only reason the R90/S ended up with those beautiful Dellortos is that Bing had nothing suitable at the time. By 77 the Dellortos were gone as Bing had the 40mm CVs. None of my 3 running Airheads have Bing carbs, either Miks or Dellorto. Haven't decided what I'll put on the 67 R60 when I get it restored.

[lkchris]

When I had my airhead, my major issue with the Bings was the lack of an accelerator pump to help with cold starts. Even though my bike was in good tune, inevitably I thought I would end up at a high altitude campsite at some time, and the bike would cold soak overnight at sub freezing temperatures. With the 20W - 50 oil now reduced to the thickness of molasses, I am confronted with the morning start, and the engine won't turn over fast enough to create enough vacuum to lift the slides a bit and get enough mixture into the combustion chambers so that the little fires can begin. With a pumper carb, you can (in theory, at least) twist the throttle a few times to pump some fuel into the cylinders.

This is course is what the "chokes" (auxiliary carburetors) are for.

Like any engine, the Airhead requires extra air to run on a rich mixture, and this is accomplished by cracking the throttle open a bit when cranking a cold engine.

Cracking the throttle open a bit when cranking a cold engine also helps it spin a bit faster since you've eliminated some of the throttle obstruction, making it easier for the engine to "suck" air.

[rinty]

This is...what the chokes are for.... lkchris

That's the theory. But if that bike's been sitting for some time and has been cold soaked, and the the ignition / fuel delivery system is not 100 % perfect, it's going to be difficult, if not impossible, to start with the starter motor.

My airhead, (which was kept in meticulous tune by Dave Anderson, our local genius) spent its Canadian winters in my insulated, but unheated, garage. I religiously kept the lead acid battery charged up. On a warm spring day, the garage temperature would be about 10 hours behind the outside ambient, when I would commence the spring starting drill, by the book: taps on, full choke, throttle open 2 cm, ad nauseum, and the thing would usually light off. If it didn't, I would go away for 5 minutes, come back, and start again, and then it would usually go.

Anyway, those days are over now.

I still think the Bings are excellent carbs: for southerners, and for riders who use AGM batteries. :) Actually, I think they're excellent carbs, period, but that's just my opinion.

If I ever get another airhead, I will bite the bullet, spend $1,500, and put a kicker on it. Then, no more problems.

Rinty

[28796]

If I ever get another airhead, I will bite the bullet, spend $1,500, and put a kicker on it. Then, no more problems.

Rinty

If you do make sure it's no bigger then a 750 or low comp 800 or that kicker will be strictly for show. Even on a 750 I doubt it would do much if the bike sat outside in the cold especially if you were running 20/50.

[barryg]

I appreciate your comments on these types articles Paul, well thought out. It seems the riders who want to change anything from stock are kind of put down by those who want to keep the bikes totally stock and vice/versa. I'm kind of all over the ballpark. I like every thing from concours original to highly modified. Mostly, I like doing little upgrades to my bikes to make them more rider friendly to me. I think adding fuel injection or turbo's to airheads is neat for the right people doing it. Those with deep pockets or have the ability to put those kind of systems together to make them compatible to the bike. Most people do not have the ability to see a project like this thru to completion and enjoy the results. These are not simple upgrades but complex systems, easily seen in tech articles, but much harder to bring to a finished product. From reading the history of BMW's, supposedly when the R90S came out Bing did not have a carb big enough, so the carbs were farmed out to Dell'orto.

[rinty]

...that kicker will be strictly for show..... Bikpaintr

I agree, if it's been sitting outside in a northern winter with 20w - 50 in the sump, it's not going to go. But my garage never gets colder than - 10 C, even at - 30 C outside, and in the spring it would be at around the freezing mark inside, in the morning, if it was + 10 C outside. Then what you can do with the kicker is turn the engine over a bunch of times with the ignition off, to get the engine loosened up, and then use the electric start. It's like pulling the prop through a bunch of times on an aircraft engine before winter starting it. I used to use 10w - 40 for winter oil in my airhead, but it didn't seem to make much difference for cold starting compared to 20w - 50. To be fair to my gold old airhead, it was only the first spring start each year that was tricky, and if it didn't go, a jump start would always do the trick. But with AGM batteries, you don't need the jump.

....riders who want to change anything from stock are kind of put down.... barryg

I'm not sure that's necessarily the case, Barry. I used to own a heavily modified RS, and whenever I brought it to rallies, I got a lot of compliments on it. But when you get into fuel injection for airheads, you are right at the edge of the mods envelope, and if you ask the question, you'll get lots of cautions from the MOA folks.

Rinty

[easter85]

I have had a 1978 R80/7 since it was new and it now has approximately 80,000 miles on it. I have never had a problem of any kind with the Bings. A couple of times they have been rebuilt just from age. They have been wonderful.

I live at sea level in Texas; but I have ridden this motorcycle to Alaska and back. Have been to Canada and back on another trip and have been over the Rocky Mountain National Park highway several times. I have operated this motorcycle down to about freezing without any problems. Idles fine, runs fine, starts fine.

I'm glad to find out the Bings are so bad. I also had a 1978 R100/7 and never had any problem on that bike either. I guess I have just been lucky.