Carburetor Vs Fuel Injection - Harley Forum

myt evo · #1 03-22-2008, 11:43 PM

Never having owned a Twin Cam I have a question for those with first hand experience with performance modifications to the carb equipped TC's and even from those that had a shop do their performance work for them on their carb equipped TC's. No need to explain the pros and cons of carb vs injection, these are well documented. There may be a TC in my future but nothing newer than an 06 since that was the last year that the carb equipped TC's were available. My reason? I prefer to do my own work and I like to tinker. I would rather not be tethered to a dealer or an after market shop by a computer cable and have to do a down load every time I decide to tinker. So my question is, are these down loads required with carb equipped TC's? I know that it has probably been written about before but I don't feel like going back through years of publications to find the information. Any and all info would be appreciated.

botzman · #2 03-23-2008, 12:19 AM

Hey MYT,

My 05 Twin Cam was carbed. No downloads. Had to drill it out to get to the mixture screw, installed a thunderslide and jet kit, pipes and SE Air cleaner. The thing still puked and coughed more than my EVO. Had it dynotuned and it made a nice improvement for the whole 30 minutes I got to ride it before I parked it in the side of that truck. I believe the downloads are for the injected bikes only.....BUT I'm no expert. Botz

Wrightturn · #3 03-23-2008, 12:30 AM

No. Without EFI you escape the good and bad that it brings. I have a friend who just changed pipes on a 06 RK and is up 800 + to the dealer. It still acts lean.

On Fri I rejeted an 06 Sportster that had SE pipes and a K&N filter. Total cost 3.00 plus 1 gasket. Runs fine.

Wrightturn · #4 03-23-2008, 12:44 AM

Hey botz,

Opinion on the Thunderslide kit. They are overkill in most installations. You go from lean to rich and still run poorly. Most of the bikes brought to me are referral. If you are just doing breather and pipes a low speed jet and maby a needle change are enough. If you don`t use all of the kit you are ok but have paid for parts you don`t need until well into stage 2.

whylee · #5 03-23-2008, 02:59 AM

If the FI systems were set up the way they should be they would be great. They dont set them up to compensate for any changes, they can and should be set up that way. If a engine is set up wiyh 02 sensors, then it should self adjust. There should be no reason to need any fuel tuners, but then they would loose money on all the aftermarket tuners.

evoKENevo · #6 03-23-2008, 10:01 AM

Hi Guys

I think we've kind of drifted-away from myt-evo's original question here regarding weither or not a Carbed TC engine also needs "downloads" just to "tinker" (good word) with. I'm assuming (bad word) that they do,since there's nothing inside of what used to be a "nose-cone" except for a cam OR crank

sensor for the ECM to reference..but,THAT'S it in MY head .. and,ain't sure about that much either..more help,please

Ken

botzman · #7 03-23-2008, 10:14 AM

WRIGHTTURN,

I couldnt agree more. It never ran perfect and was a slug from day 1. It was for touring only and not racing so I wasnt looking for an HP maker just a good running bike (although the extra ponies couldnt hurt either). It would have been nice to have it running right with the perfect mixture. As I said though the Dyno helped but never got a chance to really ride it. My EVO would run circles around that twin cam any day. I still like carbed bikes. I wouldnt recommend that Thunderslide setup to anyone. Botz

Wrightturn · #8 03-23-2008, 10:59 AM

Hey Ken,

With a carb you get electronic ignition and nothing else. The system has no control over fuel delivery. You can`t alter the timing without changing the ignition module. SE modules retard timing either 5 or 10 degrees but they are fixed.

Have not seen an on board adjustable ECM for EFI but I am sure it could be done. I am also sure some guy would blow up his bike with it. With a carb fuel delivery is fixed by the carb and advance by the ignition module. Nothing to download into.

In the late 70s there were electronic carbs. They were every expensive. A friend put a V6 into a VW bus without the black box. Holley made a control device that allowed you adjust the mixture from the dash. Fun to play with.

myt evo · #9 03-23-2008, 11:07 AM

I fully agree with you entire response botz concerning the use of a bagger and what an evo can do. But who knows! The time may come when I might want to add some serious ponies to it. Eventually the EPA is going to put the cabosh on any type of downloads or modifications! Then what do we do? As long as it's left in my hands damn skippy I'll be able to make it run! Whylee is also right but hell will freeze over before that happens!

myt evo · #10 03-23-2008, 11:16 AM

Thanks for the info Wrightturn. Do you or anyone else have more in depth info on this? I'm asking because I know threw the years some of the electronics have changed on the TC. It took me awhile to get used to the small amount of electronic items on the EVO! Damn I still wish they made the EVO.....SHOVEL.....PAN.......KNUCKLE...... FLATTY.........................................