That is a bit strange. The only time I get below 50 is at extended high speed highway jaunts. Also need to add oil at that time.

When I had my Savage, I would have been surprised to get 49mpg. I usually got about 45-46. I think I did run a little rich. I had jetted and needle spaced for an Emgo shorty muffler, then moved to a Dyna. However the bike ran great that way. Minimal cold enrichment needed and never any surging at any speed.

If your engine is just a bit "cold blooded" and you get a bit of a lean surge until the bike is warm........that to me is a good indication that your jetting is nearly ideal.  A lean surge on a cold engine is a good indication that you are not jetted "rich".

On the Savage the spacer/washers are on top of the needle, and a little spring holds the needle up against the washers/spacer.  So the thicker the stack of washers the leaner the "mid range" will be.  I like to keep adding washers until I get a noticeable lean surge....then start removing them just until the bike runs smoothly at partial throttle when fully warmed up.  A little bit of a surge on a cold engine is a good thing provided it goes away when the engine is up to temperature.

For anything but full throttle acceleration or highway work where you are holding the throttle more than 3/4 open....the main jet really isn't in control of the fuel mixture or mpg.

I suggest you start with a #147.5 main, a #50 pilot and 3 washers in place of the white spacer, get a new float needle if yours is old and leaking, check to see if your TEV diaphragm is old and stiff and replace it if needed (they don't last forever), and set your float level to the factory setting.

My cafe' bike is light and doesn't have a windshield, and the engine has a Wiseco 94mm, performance cam, Mikuni VM carb and tall gearing.  I regularly get in the high 50's for mpg, and if I ride around with pokey guys on cruisers I can get in the high 60's for mpg.

I would suspect that your big windshield and saddlebags are hurting your mpg quite a bit.....try riding without a windshield and see what happens (maybe not a good idea in December).   Also check to see that your wheels rotate easily and a brake is not dragging, and that your tire pressure is up. 

Well , it didn't warm up as much as the weather lady said it would today. So
instead of taking a ride today I took the S-40 to the shop.

I started to take the carb off but - after seeing that the carb don't come with out removing the airbox first it occurred to me that I don't need the carb off I need the top of the carb off.

OK ,  I did get to the white spacer but it wasn't easy.   I had to use one of those left drill bits to break one of those little screws loose inside the "Slide "once I got it out.

What I found was that the needle has six groves and a "C-clip".   The clip was on the third from the bottom .  

So

I moved the clip to the fifth ring and tried it out ... it was "WAY WAY to much .   So I pulled it out again and its in the fourth ring now and works good  

What the MPG will be ... I hope to find out tomorrow  .    

Then maybe go changing jets ???  

When was the last time you cleaned or replaced your air filter?

What !  These things have air filters ?   You clean them every 100,000 miles don't ya  ?  

I'll check on it tomorrow before I take it out for a hundred-mile loop
...........

Yea , lowering the needle by two rings might have worked with a larger main jet ?  

There was a dead spot at low throttle but it cleared up with more throttle but was still clearly too lean !  

The spring under the needle was too big of diameter , it kept getting past the clip and pushing the white spacer off the needle while I was getting it reassembled.  

So , I used a smaller dia. spring of about the same strength and length.

Mine is a 2005 model , and I got it with about 3K miles on it .  It was only a few years old when I got it. , I think it was a stock machine. ??

I believe the jets are 152.5 and 52.5 , but I'll find out for sure some warm/wet winter day between now and spring.  

Hay Versey I want to know what you did to the BEAST ! to get 140+ miles before hitting reserve ?    That's awesome !!!
.....................

MMRanch wrote on 12/02/21 at 16:36:46:


I often wonder how many motorcycles are running around and are jetted too rich.  A bike that is too lean runs unevenly, surges and backfires and is a pain to ride - but a bike that is a bit too rich starts easily and really doesn't show any symptoms.....other that a sooty exhaust pipe and poor fuel mpg.  A properly jetted bike runs much crisper and gets better mpg and is a joy to ride.

When I was fooling around with my engine it took me about 5 jet changes to get things perfect.  (I start with a #50 pilot, #150 main and 3 washers on the needle).

The first thing I do is work on getting the pilot jet correct......the correct size will provide for the smoothest idle at 2 - 2.5 turns out.  If you can turn the fuel mixture screw all the way in and the engine still runs - the pilot jet is too big......if you have to turn it out more than 2.5 turns to get a smooth idle the pilot jet is too small. (You must turn the idle speed down to around 800 rpm to get this fuel mixture adjustment correct).  Some bikes are happy with the #50, some want a #52.5....and one was happiest with a #47.5....all had the stock paper air filter.  (I really don't think the type of filter has much affect on the pilot jet, as the air flow is so small at idle that there will be very little difference in the flow provided by the filter.

The next thing I do is work on the main jet.  I will put in bigger main jets until I can hear/feel the engine begin to "blubber" under full throttle.....then go smaller until I can hear/feel the engine is lean by being uneven - then I will choose to keep a jet in between those two extremes.

The final thing I do is set the slide needle height......I keep adding washers until I can feel the bike "surge"during light throttle settings (which shows the bike is too lean).  Then I start taking away washers until the light throttle settings provide for smooth running.......in my opinion this is where most of the riding is done (1/4-3/4 throttle), and it has the most affect on fuel mpg (other than 3/4-full throttle at interstate highway speeds).

When a bike is jetted this way it runs the best when on the throttle and gets good fuel mpg.  The bike may get a little noisy when you allow the throttle to close completely while decelerating (compression braking) or shifting gears - as the fuel mixture goes lean when the throttle is closed and the only fuel is provided through the idle circuit.  You can easily stop the backfiring/noise by using your right wrist to crack the throttle open a very small amount and giving the engine a bit more fuel (you only need to use enough throttle to stop the noise....not enough to make the bike accelerate).  And......if the bike is too noisy you can go up one size on the pilot jet and make the mixture at closed throttle a bit richer without hurting your fuel mileage.....however you may need to make an adjustment on the needle height after going larger on the pilot jet.

I leaned mine out and still hardy ever get much over 50 mpg but I'm a big person.  When I got the bike I never got much over 42 mpg.  It had a 55/155 combo in it with a Dyna pipe and while it sounded cool, it ran like a turd.  It runs better now but the exhaust note changed a bit with the jetting cleaned up.