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2004 Shadow Aero 750 poor mpg, backfiring on deceleration and running rich

5K views 12 replies 7 participants last post by  Harryc 
#1 ·
My 04 Aero had 8450 miles on it when I bought it July 2013. Since then I have put 10K+ miles on it. It has since the day I got it back fires when decelarting unless I completely close the throttle, runs rich plugs are black and sooty looking and have never gotten more than 32 mpg. Ran lots of Seafoam through the fuel system, replaced the air filter, replaced the plugs. I have taken it to two highly recommended local shops and still no difference in spite of the first shop keeping it for 3 weeks the second one for 5 weeks. I have ~$400 in shop charges so far and would gladly pay the right shop to have it running right. First shop said they fixed an intake leak next shop said they cleaned the main jet in the carb. Having spent my entire working career fixing airplanes and autos I am capable of rebuilding the carb but frankly don't want to spend my precious free time doing so. Does anyone know where I might take the bike in the central east of Florida to finally get it fixed? I live in Sebastian which is almost exactly half way between Miami and Jax.
 
#5 · (Edited)
I would think you adjust the a/f screw for a leaner mixture would solve the problem. For example, when my bike was running rich (popping on decel vs. backfiring), I adjusted the a/f screw richer and that solved the lean problem. How many carbs on the Aero? If 2, then maybe you have to sync them after the adjustment, dunno.


I have taken it to two highly recommended local shops and still no difference in spite of the first shop keeping it for 3 weeks the second one for 5 weeks. I have ~$400 in shop charges so far and would gladly pay the right shop to have it running right.
????!
 
#7 ·
That's a single carb bike unless I'm mistaken. You should be able to tweek the a/f and lean it out some. Working on 20,000 miles? Valves every been adjusted? Honda calls for it to be done @ 8000mi., but many will hold off until 10-12,000, but almost 20 is stretching it. Also, check the numbers on the plugs to make sure you've got the proper plugs in it and not too cold.
 
#11 ·
Adjusted the valves although they were in tolerance I set them to factory spec. That didn't help didn't hurt. Pulled the carb off took it apart thoroughly cleaned everything. I did notice corrosion and pitting on the start enrichment valve, accelerator pump shaft and on the metal piece that the air cut off valve diaphragm mounts to. I suspect this bike sat with fuel for a long time prior to my buying it. I added up cost of replacing all the corroded parts new main and low speed jets and the cost is ~$160. I can buy a carb for $320 and am seriously considering replacing the carb. I also could not break loose one of the screws holding the coolant tube assy to the carb which prevents me from thoroughly soaking the carb in a good carb dip such as Berryman's. Yet another factor that has me leaning towards replacing the carb rather than remanufacturing it. Thoughts, comments?
 
#12 ·
This carb has a pilot screw that requires the use of a special tool to make any adjustment. The head of the screw is round with one flat side picture a flat tire round on all sides except the bottom. Does anyone know where I can buy one? Honda chose to put this in a real inconvenient spot too. It sits on the bottom of the carb as mounted to the bike making it darn tough to adjust withe bike running.
 
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