At Doc's request I'll start another thread on this since I'd started it in the "Need Advice from carb guru" thread and it wasn't the main topic.
As a refresher/reminder I've been adjusting the carb settings in search of better mpg.

Before rejetting; Stock carb running Arlen Ness Big Sucker Air kit and RH 65 Special slip-on pipes and AIS still installed; 42-45 MPG avg.

After rejetting using a Cobra jet kit; 175 main, 37 pilot and washer, clip on 4th groove from blunt end, spacer, washer and PMS at 3 1/8 turns out. MPG with that set-up was 31-33. AIS was removed during this period.

First change; installed a 35 pilot and the MaxAir MaxMix PMS screw, set at 3 1/8. MPG up to 35 avg. Still not where I wanted to be.

Second change; adjusted the needle setting to, washer, clip on 3rd groove, spacer and two washers.

Just got back from a 200 mile ride and my MPG varied greatly. First half of the ride was on a state highway going thru small towns with some stop and go traffic and a top speed of 65-70 mph; MPG was 42.1, which is, in my book, acceptable.
Second half of the ride was much lower; interstate with an average speed of 75 mph fighting a 15-20 mph headwind (according to the weather channel) and the MPG were back down to 33.9!!

Now for the questions! Would that kind of wind affect MPG that much or could I still be running rich on the needle? Could I lose one of the washers or would that lean it out too much? And regarding the PMS; If I'm getting some popping and backfiring at slower speeds while down-shifting, should I go in slightly on the PMS?

Thanks for any input or advise.



In The Wind,
Aaron

man I hate when I hit the wrong button and loose everything I typed ... I can get gas mileage between 42 to 50 MPG depending on how I'm riding 50 - 52 at 50 - 55 MPH and if I'm running 75 - 80 mph then 40 - 42 mpg

If you're not afraid to pull the carb then lean it out until you get lean symptoms and then go richer until the symptoms go away... ~Guido

A headwind especially with a windshield will help to eat the gas. If you still at 3 1/8 on the PMS try going in on that.

Thanks for the input guys, but after reading some other nonrelated threads, I think I must have misinterputed Doc's recommendations regarding this issue from a previous post.
His suggestions were to do the following one at a time and see what happens;
1) put in a DJ170 main and try it
2) move the needle settings to where I have them now
3) adjust the PMS as needed afterwards

I read that as being able to do one or the other, or both. But I just read a post regarding needle settings and clip placement, and by adjusting the clip to the 3rd groove I've actually gone richer since I didn't put in a 170 main. Am I correct in this? So what would happen if I were to put the clip back to the 4th groove but kept the 2 washers? Wouldn't that lean it out slightly from just having one washer? I really don't want to go with the 170 main because according to Cobra/DJ that jet is for use above 3,000 ft. and here in Mo. we're well below that.

Thanks again and sorry for being such a pain!

In The Wind,
Aaron

You're not a pain. We've all been there.( And still are ) Adding a washer will make you richer. You will be pulling the needle further out of the main which will let even more gas in. Going from the 4th to the 3rd groove ( from the blunt end ) is leaner because it's dropping the needle futher in the main letting in less gas.

The main comes into play at about 3/4 to WOT. You'll notice cruising at 60-70 you're probably at around 1/2 throttle. Most cruising is done on the needle, not on the main (unless you're passing).

So what does this mean .... it means it's not the speed that you are going at but the position of the throttle. A headwind will affect the position of the throttle and may cause you to be into the main jet area.

I suggested that you verify with the WOT test whether the DJ 170 will work. No use having a larger main than necessary if you want to save gas.

In general, if you want better cruising mileage then you need to play with your needle. As Musky replied - clip up = leaner, clip down = richer.

You can keep moving the clip up (leaner) until the performance suffers. So if you're at 4 th clip with one silver washer, you move to 3 rd clip with 2 washers, then 3 rd clip with one washer, etc.

Finally the #35 is usually sufficient for most but you'll next to readjust the PMS after fiddling with the needle.

If you are getting popping on decel and it's not an exhaust leak you're a bit lean on the PMS. Turn it out 1/8 - 1/4 turn at a time until it disappears.

Doc

Musky and Doc,
Thanks for clearing that up for me and setting me straight. I'll remove one of the washers and see what happens. I'll also check for an exhaust leak before adjusting the PMS.

Thanks again!!

In The Wind,
Aaron

Update; Removed one of the washers last night and adjusted the PMS to about 3 1/4 turns out from 3 1/8th. So now I'm at washer, clip in 3rd groove, spacer, one washer, DJ175 main and 35 pilot. Took it for a ride and was still getting a slight "pop and flutter" type of backfire at slow speeds only (while downshifting) and had a little throttle hesitation off idle. Backed the PMS out about another 1/8th. So now I'll have to wait and see how the new settings are going to affect my MPG and make sure I haven't leaned it out too much.
Thanks again for the help and advice!

In The Wind,
Aaron

that´s a pretty big screen you´ve got there.

fighting a headwind would definately make your fuel consumption go up.

have you thought about trying it out on a run without the screen before changing the jetting in case it is the main contributing factor?

Erizo,
I'm sure the windscreen is a contributing factor, but going back to my first post; I was getting an avg. of 42-45 mpg before having the bike rejetted, and I was running the windscreen then too. And I've actually cut about 2 1/2" off the top, so it's 17" from the top to the top of the headlight shell. So changing the jetting was the logical way to go it seems. I just don't want to get it too lean and risk running too hot so I'll have to keep an eye on it.
Thanks for the input!


In The Wind,
Aaron