EFI to Carb conversion

[Easy-X]

More of a thought-experiment than anything else...

Plenty of bikes like mine were originally carburettor-based and later got swapped to EFI. As EFI is a "black-box" system which is effectively unalterable I was just wondering the advantages/disadvantages of taking it back to old-skool stylee?

I would imagine one would at least need a carb, CDI unit and possibly a new coil. Plenty of rewiring ofc but nothing too tricky if the "original" non-efi wiring diagrams are available. And obviously you have the joys of pissing about with jets and mixture screws.

After that, what would happen about the emissions? I don't see anything in the MoT manual apart from exhaust noise. Cheating the London ultra low emission zone might also be a concern.

And finally, would it actually make any tangible difference? Certainly HD owners have previously been spitting chips over EFI so it must be worth doing for some engines.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[temeluchus]

Some motors might not have crank sensors, so that might make fitting an older style standalone ignition a bit fun.

Wiring up a TCI style electronic ignition is trivial, and shouldn't present a problem for anyone who understands electrics.

The inlet manifold(s) might present the greatest challenge tbh.
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Some shite cruiser. Now with guns and FREEDOM!

[stevo as b4]

Obviously not your 125 are you looking at messing with again?

Personally if I had an EFI engine and didn't need to have a carb for weight or waterproofing reasons then I'd always look to keeping the EFI system and making it reliable and rideable if not already.

For an out and out race engine or anything with forced induction, particularly if I was attempting to run it on modern shit pump fuel, I'd not consider anything other than EFI personally.

Oh and why do you always keep banging on about emissions? Unless you live in the ULEZ and have to ride 2007> bikes, then emissions are a misnomer for bikes.

Saying that though, emissions when looking at say Euro 7> and manufacturers needing to deliver better mpg and maintain good performance, is a set of hurdles they will really struggle with. Its a triangle that you can only ever get close to one corner at a time, at the expense of the other points.

Currently they are even sacrificing engine life and repairability to meet emissions/mpg/ performance.

[Hetzer]

An EFI is eminently "alterable" with a PC or similar.
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"There's the horizon! Ride hard, ride fast and cut down all who stand in your way!"

[Easy-X]

No, not something I was aiming to do on my bike! Someone said something on another thread that set off a chain of inquiry. The mad thought was "10 gazillion articles on carb to efi... I wonder if anyone's done it the other way?"

Crank sensors, yes... not thought of that. Inlet manifold... I would guess if the design was originally carb but converted that wouldn't be a problem (if old parts still available) but a freshly designed EFI bike would be a challenge I guess.

With regards to emissions I care only slightly about the environment as in, why not if you're not sacrificing much but I'll have a read up on Euro7 specs. I live just on the edge of London and my previous "eco as in free congestion charge" Euro 4 ultra-low-emissions diesel that we were all told to buy is now the bad man so not only did I have to start paying congestion charge a couple of years ago I now also have to pay another £12.50 to enter the ULEZ with it

I pretty much bought a motorbike on a whim and now it's saving me £22.50 + parking every trip into town! Funny how life turns out
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[stinkwheel]

Look. A kit to replace the EFI system on your Enfield Bullet with a Mk 1 concentric Amal carburettor.

https://accessories.hitchcocksmotorcycles.com/accessory-shop/amal-carburettor-conversion-kit-efi-models/22197

Really.

In fairness, Enfield owners DO like to piss around with their exhausts, air filters, cams and compression ratios and the carbs are very well understood by now. They could also just plug in a dynatune box, but where's the fin in that.

One thing most people don't realise is most FI bikes have a fuel pump in the tank which may well need to be replaced with a tap (and definately if you're relying on an Amal needle valve to stop petrol pissing everywhere!).
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Easy-X]

[stevo as b4]

I'm no tech head, but on a water cooled four stroke engine, emissions aside you can with the right design, parts, electronics and experience make an engine that runs better and stronger over a wider percentage of the rpm/load range with EFI.

You'd have more area under the curve than with the most expensive race carb money can buy, but only if it's done right without compromise. EFI sometimes gets a bad press for ruining bikes or making them less rideable. But it's unfair as they are injecting for reasons like noise and emissions and mpg. Put EFI on a level playing field with carbs (maximum power everywhere) then all you have against EFI left is weight and complexity. Cost isn't even far apart now.

The only place I don't like to see EFI is on two strokes, as firstly it's pointless trying to clean up dirty stinking oil burning obsolete engines, and secondly I've never seen EFI make one run better. Things like overrun fuel cut of isn't friendly to two stroke engines and you therefore can't apply it in the same way. You also don't get time at high revs in the operating cycle for EFI to work, so a wet manifold (carb) is the way to go.

[Easy-X]

Yes, I mentioned something about 2 strokes and Euro 4 a while back. It seems, for top models, they can do a variant of EFI that is at least "okay" versus the carb version. But when you study all the things they needed to do to get it to work you pretty much come up with something of comparable complexity to a 4 stroke engine and then... what's the point?
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[stinkwheel]

[Easy-X]