Hypothetical carb conversion.

[King Herald]

Chatting to an old fella on an Airhead today, the subject of fuel injection versus carbs came up and he was telling me about some guy he knew on a Oilhead GS who had swapped carbs onto his bike in darkest Africa, or some such place, when the fuel injection got stolen, or broken. Or something along those lines. 

Simple gravity fed carburettion sounds quite appealing, and it would be easy enough to fit a couple of suitable sized carbs, but would the Motronic still provide the spark, at the right time, ignition advance etc? Would it still need the TPS setup to move with one of the carbs? Or is there more to it? 
It’s not something I’d do without good cause, as the fuel injection simply works so well, but it is an interesting concept.
 

Thoughts? Anybody done it? 

[dirtrider]

1 hour ago, King Herald said:

Chatting to an old fella on an Airhead today, the subject of fuel injection versus carbs came up and he was telling me about some guy he knew on a Oilhead GS who had swapped carbs onto his bike in darkest Africa, or some such place, when the fuel injection got stolen, or broken. Or something along those lines. 

Simple gravity fed carburettion sounds quite appealing, and it would be easy enough to fit a couple of suitable sized carbs, but would the Motronic still provide the spark, at the right time, ignition advance etc? Would it still need the TPS setup to move with one of the carbs? Or is there more to it? 
It’s not something I’d do without good cause, as the fuel injection simply works so well, but it is an interesting concept.
 

Thoughts? Anybody done it? 

Evening King Herald

 

It has been done but I wasn't involved so don't know the details on spark or fuel supply. 

 

First problem is fuel supply as it would probably need a low pressure external fuel pump as the fuel tank has no bottom fitting outlet for a gravity fuel supply.

 

Installing carbs would be fairly easy but the fuel tuning might take some work, would also need some  thought on getting the throttle cable brackets &  attachment worked out. 

 

Spark would be more difficult as it would need a working a calibratable TPS, along with a working engine RPM, engine temperature, & air inlet temperature into the spark control (probably just use the stock HES &  Motronic).

 

Not worth the effort as the fuel injection works pretty good (usually better then carbs would). 

[Skywagon]

Unless he had to do it because his fuel injections couldn’t be repaired, I have no idea why you would trade FI for carbs. I hate carbs with a passion. I helped a friend put a kit in a quadrajet about a month ago. It reminded me how much I hate them. 
 

My dad use to tell me when a carb goes bad, get rid of the vehicle. I use to carry accelerator pumps in the glove box

[King Herald]

Morning gents,

No, it doesn’t sound like a simple or smart move to make when the fuel injection works so well. 
I’ve lost track of the times I’ve seen bikes for sale with “just needs the carbs tuning’’ in the description, meaning “I’ve tried for ages but can’t get it running right”. 

[MarkAZ]

Many years ago I was in the Peace Corps in deepest darkest Africa (Dem Republic of Congo) and I can tell you that the people there come up with some amazing fixes for vehicle problems. It wouldn't surprise me at all that someone would figure out a way to do this with only the simplest of tools and parts from other vehicles.

 

Somewhat the opposite...I heard somewhere about someone who installed fuel injection on an Airhead. IIRC, there was something about using an early VW injection system and he had to fool the system about some missing sensors. My old R100RS ran just fine with the Bings. Some people just like the challenge of doing things like that, I guess.

[King Herald]

14 hours ago, MarkAZ said:

Many years ago I was in the Peace Corps in deepest darkest Africa (Dem Republic of Congo) and I can tell you that the people there come up with some amazing fixes for vehicle problems. It wouldn't surprise me at all that someone would figure out a way to do this with only the simplest of tools and parts from other vehicles.

 

Somewhat the opposite...I heard somewhere about someone who installed fuel injection on an Airhead. IIRC, there was something about using an early VW injection system and he had to fool the system about some missing sensors. My old R100RS ran just fine with the Bings. Some people just like the challenge of doing things like that, I guess.

It would be an interesting challenge, maybe one day I’ll have a go. I’d like to buy an old clunker Oilhead and strip it down to its most basic form, bobber style, single seat etc. Some Harley fuel tanks, battery under the seat,  twin exhausts, carb conversion….. maybe one day.