Going back to stock on main jets..

[L J VFR]

After pondering on this for a few weeks, I verified it last night with my tank refill..  I believe my bike is running too rich..  I personally have 3 total shims, 105 main jets, removed resonators, and a K/N filter..  I got my worst fuel mileage ever with 40mpg on this last tank fill.. Riding back and forth to work, nothing changing.  My plugs are suspect as well..  I personally am going to eat my words on previous threads and I am going to go back to 102 main jets..  I think the 105 jets are too rich for my specific bike.. After installing them, I have seen no personal improvement on performance.  Just rich plugs and bad fuel mileage..  I may also decrease my shims to a total of 2 instead of 3.  I will begin this tonight after I ride home..  After looking at Dave Dodge's shim kit and what it says, I believe he is right.  Add 105 mains only for aftermarket exhaust..  Just my .02 worth, thought I would share..

[TLRam1]

Lance,

What you might do first before you pull the carbs is reduce your shims to 2 total, this can be done w/o removal of the carbs, I think 3 shims total is too much. I think your jets are fine, it's your shims, they come into play between 1/4 and 3/4 throttle for the most part.

The good part is to recognize this as you did. You have to go too rich and too lean to find your limits and the middle where it should be. 

No words to be eaten, all of this is trial and error Lance even if you have the fancy equipment!

[L J VFR]

Thanks Terry, may try that..  Just don't know if removing 1 shim will cure it or not..

[dgc67]

A couple of things to consider:
1.  when tuning (especially fine tuning) make only 1 change at a time.
2.  weather conditions have a strong effect on tuning and have to be considered when tuning to find a "balance".

Back in my sportbike days I used to re-jet often to match weather conditions.  Of course I was more anal back then and had way more time on my hands. 

[Fitzgerald]

I don't know much at all about shims or jets.   My bike normally gets 35-42 mpg depending on how I ride.  Is this normal?  I noticed that you were complaining about 40 mpg.  I talked to a guy who rides a VTX 1300 and he said he gets 50mpg.  I thought I got less because of the 4 cylinders.
Also, my bike has the original exhaust with the baffles removed. It was like this when I bought it.  I heard that I would have a little more hp with the baffles in.  Does anyone know if this is correct?

[L J VFR]

Fitzgerald, When I bought my bike it was completely stock..  Got 48-52 mpg constantly.  When I changed the shims and added k/n filter I still got 45-50 mpg.. I cut the resonators out and added 105 main jets (102 is stock) and my mpg has dropped significantly to 40-45mpg. My plugs continue to stay wet as well.  Therefor, I believe I am running rich.    I don't remember what year model your bike is, but if it is a 3rd gen.  I would suspect you may need carb work.. Seems to me your bike may not be getting the fuel mileage it could, or you may just ride it hard..   I'm not sure if your bike is loosing power due to removing baffles or resonators, if it is it shouldn't be significant I would think..  You may try some seafoam, everyone loves it here, and it helps keep your carbs clean..  I just went thru a can myself..

[Charles S Otwell]

I have always averaged about 50 mpg (muffler mod only).

[Fitzgerald]

I had it tuned up last year, spark plugs changed, valves adjusted, radiator flushed, etc.

I don't know if the jets were changed when the resonators were removed.  it seems your bike and mine have similar mpg though.  I'll monitor my riding style and mpg. I consistantly get about 96-100 miles per tank before switching to reserve.

I went as far as changing the air filters but I don't have the time, space, or service manual to start tearing the bike apart any further than that.

[hootmon]

Fitzgerald, remind us again what year your bike is...

[Fitzgerald]

97

[L J VFR]

Last week, my bike hit 92 miles and started to bog down.. Had to switch to reserve..  Not too happy.            Usually get 105-115 before reserve..   and that's around town..

[Fitzgerald]

Was that before or after the Seafoam? Do you run regular or premium gas?  Would that make a difference?

Switch those jets then give us an update. 

[L J VFR]

Allright guys, took 1 shim (1 shim only)  off of each needle last night as requested..  Will give a follow-up after Bikes Blues & BBQ is over..     Hope to put some significant mileage on the bike during the event..

[Curtis_Valk]

I believe a few of us are seeing a hit in gas mileage because of ethanol.  A few years ago only the "cheapie" gas stations had ethanol blend.  Now ethanol is ubiquitous.

Most of my Magna riding was before ethanol was unavoidable.  When I first got my '99 I would occasionally hit 50+ mpg, but after getting used to her I settled down around 45 plus or minus.  I may have dipped below 40 a few times, but that was not the norm.

Curtis

[lragan]

My '96 has Cobra pipes, K&N Air Filter, DRP-64550 Shim/Jet Kit installed as Greg instructs in http://www.magnaownersoftexas.com/tips.htm#A1.31

Austin does not have mandatory ethanol, and I avoid it when possible.  My mileage varies from 45-52 mpg.  Longer rides are typically nearer 50, while putzing around the back roads like I love to do is nearer 45.  Once got 41 on a ride back from Marble Falls in a terrific headwind.

I am happy with this result, and with the bike's performance.