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Discussion Starter #1
To all of the engine experts on the forum:

I'm looking to buy a project bike (1999 Road King). I'm considering tossing the stock engine which is carb'ed in favor of a 120 or 124, obviously FI. How much more work/parts are necessary to make this happen?

Thanks.



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Don't toss the baby out with the bathwater just yet.
With an S&S G series carb, equipped with a Thunderjet,(and perhaps a 1" spacer) and tuned correctly, you'd be mighty surprised as to the throttle response and how well it'll actually run.
You'll need an ignition such as a DTT.
Scott
 

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I'm not sure on a road king or a 1999 but I had a 2000 FLTRSEI which started life as a Magnetti Marrelli Fuel injected bike. As I changed out cams, pistons, etc the MM EFI became problematic so I did as Scott suggested above and converted to carb and things were fine for many years.

Fast forward to a few years ago and my bikes lower end needed work after 100,000+ miles so I opted for a 117. It ran good but below 50 degrees and sometimes when hot it would be a bear to start?

I converted that bike to Delphi and it wasn't too hard. My bike had the two screw in quick release fuel lines. (some bikes maybe yours had hard lines in the tank). Being originally Carbed you would need a fuel injected tank or someone to weld the fuel line bung in your tank. I blocked off one of the lines with the pingle block off fitting. I used Harley's coil, ECM (flashed to a 2002 VIN), and the factory fuel pump for Delphi in the fuel tank. I went with an HPI throttle body, yellow band injectors and all Harley Davidson sensors. You need to make an adapter to mount the coil in the factory location. If you want to go with the factory ECM you will need to marry a TSM/TSSM to the ECM. I had Dan Thayer make a harness for the conversion and marrying the TSM/TSSM.

Before the conversion I had occasional kick backs, went through a few starters and ring and pinions. After the conversion all those issues disappeared. I believe I had about $3000 in the conversion.
 

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If you use a 2005-newer ECM you can run closed-loop. Something to keep in mind. No way I'd run a carb with as good as the factory F.I. can be.
 

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The thing to keep in mind about going with a carb, there is nothing like the sound of a Harley with a carb. The famed potato, potato sound will be there that they are so famous for. Not only that, if you have the carb set right, you should have many miles of perfect starts, good power, and decent fuel mileage. Don't be so quick to give up what has worked so well for so many years. Not only that, you don't have to worry about sensors etc going out down the road. Don't get me wrong, I love my FI, but I also loved my bobber with the carb.
 

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I am not knocking a well tuned carb, I did it myself for a while. And on a stock bike with MM EFI it IS the better solution. A carb only has 3 circuits idle, intermediate, and main. With EFI you can tune fuel and ignition every 100RPMs. Many dealers and indys don't or cant work on Evolution powered bikes anymore (I know some can't work on the new stuff either). Most shops have a scanner they can plug into diagnostics these days. He is also talking about a 120/124 which does add more stress on the starter etc.

I even swapped an LS engine into a 1972 Jimmy. It was the best of both worlds reliable and efficient!

I'm not saying one way or the other is the best answer. Just do the research and make the best decision for YOU!
 

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Ahhh yes, the carb convo.......for my fellow dirt merchants, this is like the age old debate of 2 stroke vs 4 stroke

To me, Carbs were/are like Black Magic as finding the sweet spot can be tricky but when you do, life is good - Finding someone who knows carbs these days if you do not is a lost art as well - I agree with the Carb Sounding HD........Classic - I have not had to dick with Carbs since my '05 Deluxe and she was a bitch to get set....but once she was....ran like a champ

Good luck, project sounds fun
 

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Discussion Starter #8
Not exactly sure how I'll go with it. Initially probably just keep the stock setup, stock engine only has 26k miles on it.

My desired end state is an around town, high performance, bike night bike. Big motor, big stereo, big bars, big bags, big paint!


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The thing to keep in mind about going with a carb, there is nothing like the sound of a Harley with a carb. The famed potato, potato sound will be there that they are so famous for. Not only that, if you have the carb set right, you should have many miles of perfect starts, good power, and decent fuel mileage. Don't be so quick to give up what has worked so well for so many years. Not only that, you don't have to worry about sensors etc going out down the road. Don't get me wrong, I love my FI, but I also loved my bobber with the carb.
I could be wrong, but the way I understand it, the potato potato thing has more to do with engine architecture (pan, shovel, evo, etc), whether its single fire, and cam profile than the mere fact that it has a carb.
 

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I could be wrong, but the way I understand it, the potato potato thing has more to do with engine architecture (pan, shovel, evo, etc), whether its single fire, and cam profile than the mere fact that it has a carb.
That and a low idle. Can't idle that low with a twin cam.
 

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That and a low idle. Can't idle that low with a twin cam.
I don't know, my 2003 FLTSCI with a harley 205 cam, Vance and Hines mid shots, and a stage 3+ flash (no dyno around for the trike) sounds pretty much like my 1983 Shovel with an andrews B grind in it.

Potato Potato Potato
 

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I don't know, my 2003 FLTSCI with a harley 205 cam, Vance and Hines mid shots, and a stage 3+ flash (no dyno around for the trike) sounds pretty much like my 1983 Shovel with an andrews B grind in it.

Potato Potato Potato
What is your idle speed?

The older shovels and evolutions could idle at a slower speed. The twin cam is supposed to idle 950-1050 to keep the oil pressure up. Different kinds of oil pumps. Just can't get that Potato potato with the higher idle speed. But its OK to disagree, glad you like the sound of your 2003.
 

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What is your idle speed?

The older shovels and evolutions could idle at a slower speed. The twin cam is supposed to idle 950-1050 to keep the oil pressure up. Different kinds of oil pumps. Just can't get that Potato potato with the higher idle speed. But its OK to disagree, glad you like the sound of your 2003.
I don't know but it is pretty low. Part of the flash? Buddy Stubbs HD did all the work. Hell they will even do maintenance work on my 1983 Shovel. No major tear downs but oil changes, tires, batteries and the like. I never see any issues with oil pressure on either engine. I have an Indy for the major internals of the shovel.

With my HD Visa I get most of the normal maintenance free as points from purchases.
 

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That's good and bad. Its a MM EFI so there is that. IMHO easier to convert to Delphi from that. Might still be able to use your gas tank. I believe there are some MM replacement EFI systems also but I have no experience with them.
It's a bit pricy compared to a carb but probably the best conversion-kit out there; enter Zipper's Thunder Max! BTW this the M&M kit (Twin Cam, they also have a EVO kit!)

 

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It's a bit pricy compared to a carb but probably the best conversion-kit out there; enter Zipper's Thunder Max! BTW this the M&M kit (Twin Cam, they also have a EVO kit!)

What is the price? I just looked it up $2300, interesting. As I said I did it with mostly HD parts including their in tank pump. The only thing I needed to have made was the harness from Dan Thayer who also has his own "conversion" set up.

I don't see a fuel pump in that picture. They must be using the old MM pump? Another reason I wanted the Delphi as parts are still available for it. Also they way I did it it could be serviced at any HD dealer on trips and most indy's. It would be a 2002 as far as they are concerned.
 

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What is the price? I just looked it up $2300, interesting. As I said I did it with mostly HD parts including their in tank pump. The only thing I needed to have made was the harness from Dan Thayer who also has his own "conversion" set up.

I don't see a fuel pump in that picture. They must be using the old MM pump? Another reason I wanted the Delphi as parts are still available for it. Also they way I did it it could be serviced at any HD dealer on trips and most indy's. It would be a 2002 as far as they are concerned.
Yes; "expensive" is a relative question but nevertheless this kit costs almost five times as much as a quality carb-kit! :)

That's true; I just found out the other day that MoCo no longer provides the parts for the M&M fuel-pump. Luckily though that Drag Specialties still does! If not I would have it custom made with parts from Pingel.
 
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