Good Morning!
I have a couple of questions regarding jetting and how it effects fuel usage/mpg.
Before getting the bike rejetted last fall I was getting, on average, 41-43 mpg.
And that was running both the aftermarket air kit and slip-on pipes. The only adverse effect I had with that setup was some backfiring on decel. (AIS was still installed.) The stock settings/jets were; 182.5 Main Jet, 35 Pilot Jet and only one setting on the stock needle. Since getting rejetted I'm down to about 31-33 mpg, but I do seem to have better throttle response and quicker warm up. Since I didn't do the jetting myself I'm going by what parts are missing from the kit, so with that, the current settings are; 175 Main Jet, 37 Pilot Jet and according to Cobra's instructions, the clip is on the 4th slot from the top on the needle. So without losing alot of performance, what can be changed to get better fuel economy? The main jets left in the kit are; 165, 170, 180 & 185. This is a Stage 1 Cobra Jet Kit. And while I'm on the subject, I recently read in the Forum about rejetting to eliminate the fuel pump, but can't find it again. Any advise on what size jet to use if I wanted to go that route? In case it's needed for making an educated guess, I'm running an Arlen Ness air kit with a K&N filter and Roadhouse 65 Special Slip-on pipes. Thanks for any help or advise!!



In The Wind,
Aaron

Most jetting instructions and or dealers jet too rich. You will get performance but the mpg will go down. Try going back to the stock pilot and see what you PMS is set at. In the tech tips under carb is the instrtuctions for going pumpless.

I just rejetted. Cobra Loboy exhaust, BAK, 4th clip, 170 main, 35 pilot, PMS 3 turns. I went from ~42 mpg to ~48 mpg. I live in Houston - sea level, humid, and hot. 31-35 is very low.

davemcconville wrote:
I just rejetted. Cobra Loboy exhaust, BAK, 4th clip, 170 main, 35 pilot, PMS 3 turns. I went from ~42 mpg to ~48 mpg. I live in Houston - sea level, humid, and hot. 31-35 is very low.

Thanks for the info Dave (useful for others) but the two setups are probably not compatible. As you have the BAK, I assume the you have the Baron jet kit which has Mikuni jets. Aaron has the Cobra jet kit with has DJ jets.

Aaron you're lean on the top end which is being compensated for by the large pilot. Do as Musky suggested put the stock pilot back in (change nothing else).

Doc

Thanks for the quick responses! I was a little confused when Dave said he's using a 170 main jet at sea level, because according to Cobra, that jet is for above 3000 ft. But the different brand kit would explain that. As long as I only change the pilot jet, will I need to check/reset the float level? Thanks again!

In The Wind,
Aaron

As it's quick and simple to do, it's a good idea to check the float level after you've been into the carb bowl and you're getting weird results.

It's not hard to accidentally knock the float out of whack.

Doc

The guys are right, that pilot is eating your lunch money right out of your wallet! That set-up is the exact reason I found the RSC in the first place. The only real difference you should see (beside better MPG's) is it might want alittle more warm up time from you as you will be leaning the thing out on the bottom alittle.

Thanks for the help guys! I've been reading the various Tech Tips regarding carbs and I've decided that while I've got it off and opened up, I'm gonna go ahead and replace the needle valve too so I can lose the fuel pump. Anything I should be on the lookout for by doing this? Isn't it a good idea to leave an in-line fuel filter in place or will that create problems? I've been running one on my Vulcan for years without any trouble, but there wasn't one mentioned in the article. Thanks again for the help!

In The Wind,
Aaron

I'd leave a high flow in-line in considering the crap that's in gas these days.

Doc