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Poor gas milage.

Old 05-27-2015, 06:30 PM
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Poor gas milage.

I have only had my superhawk for a few weeks and seem to be getting very poor gas mileage. The first tank I put in was 3.4 gallons and I went 76 miles before the fuel light came on. The second tank went 62 miles and took 3.3 gallons. That equates to 18.8 miles to the gallon. My 3/4 ton pick-up gets 18 miles to the gallon! I know superhawks are not known for great mileage, but this is ridiculous. Anyone else dealt with this kind of poor mileage?
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Old 05-27-2015, 06:46 PM
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Is it running good otherwise? Does is smell rich when it's running? Backfire a lot on the overrun? Does it start easily with no choke.

I would check the choke (enrichment valves) and see if they are seating.
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Old 05-27-2015, 07:06 PM
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if its smelling super rich check your fuel screws as well
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Old 05-27-2015, 08:49 PM
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It does seem to backfire on over run. It will start without the choke if you give it some throttle. But will occasionally backfire when starting. I haven't noticed that it smells rich when running though.
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Old 05-28-2015, 01:46 AM
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Check your oil to see if it smells like gas.

I get 120 miles before the light.
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Old 05-28-2015, 04:47 AM
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The choke fittings on my bike were broken, resulting in the rear choke (enrichener) circuit being partly open - that was one problem.


My bike also had overly rich jetting in the needles (Dynojet needles) that I'm slowly leaning out.


My gas mileage prior to fixing the choke fittings was about 28-30 though, never low 20's, and I ride the crap out of it in the mountains - no highway.


I think you should be at least 30 mpg on a stock bike with stock jetting.
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Old 05-28-2015, 08:03 PM
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OK, no gas smell in the oil. But the exhaust does seem to smell rich, the wife even mentioned it today when she entered the garage a couple of minutes after I got home from work. The bike might have a jet kit in it. It does have aftermarket pipes on it. My choke doesn't seem to do anything, I'm wondering if it could be stuck open? But I would think that might make it run poorly once it is hot, but it seems to run ok once warmed up.
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Old 05-29-2015, 07:58 AM
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Do you have stock gearing? If a previous owner changed from stock and did not install a speedo healer you maybe going more miles than the odometer indicates.
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Old 06-08-2015, 01:32 PM
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Well I tore into the carbs today. Pilot jets were 55s in both carbs, and the mains were 185 front and 190 rear. Seems pretty fat to me, even with the full exhaust and filter. especially the pilots. New jets are on the way. Hopefully this will fix the milage problem.
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Old 06-16-2015, 10:13 AM
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Remember to check under the needles to see if they are shimmed as well - stock there should be one thin washer between the needle and slide - about 0.018" thick.


Wow your jetting was super fat - can't believe it wasn't fouling spark plugs, which, you should probably replace while you have it apart.
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Old 06-18-2015, 01:49 AM
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Originally Posted by gti52 View Post
Well I tore into the carbs today. Pilot jets were 55s in both carbs, and the mains were 185 front and 190 rear. Seems pretty fat to me, even with the full exhaust and filter. especially the pilots. New jets are on the way. Hopefully this will fix the milage problem.
Thats very big for a stock airbox. Is the filter a stock one. I would start with Hawks carb setup.
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Old 06-18-2015, 06:06 AM
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What are the stock main jet sizes? I haven't been able to find this info anywhere.
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Old 06-18-2015, 06:22 AM
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175 front and 178 rear except at higher altitudes.
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Old 06-18-2015, 11:33 AM
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And 45 idles.
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Old 06-18-2015, 11:57 AM
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My bike with two brothers mufflers, stock intake and stock air filter is running:


178f, 180R
stock needles with one #4 brass washer under each - about .08" thicker than stock - probably negligible
45 pilots
2 1/2 turns out on the fuel screws
stock slide springs
extra lift hole in the slides (much debate about this - I tried plugging one front lift hole, running two stock lift holes, and running the extra hole)


Long story short - stock jetting isn't bad, but a little lean on top (according to the dyno I could have gone one more main jet size richer to 180F 182R for maximum power)


Runs fantastic, great throttle response, gets from 30 to 35 mpg, depending upon how I ride.
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Old 06-18-2015, 01:19 PM
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Originally Posted by AndyMX47 View Post
extra lift hole in the slides (much debate about this - I tried plugging one front lift hole, running two stock lift holes, and running the extra hole)
I really haven't heard any debate about the lift holes.

I have just heard (from [email protected], [email protected] and [email protected] who were all doing factory racing development on the VTR) that 3 lift holes does not work and causes issues.

DynoJet is the only one that thinks it is a good thing and that is because they do it to all their jet kits and it is just to get the carb off the pilot circuit quickly....good for I4 but no so much with a twin.

So glad you got it to work though I wouldn't expect it to work on another bike.
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Old 08-27-2015, 04:39 AM
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After reading this post I am I contacted Jack Flash about the brass choke fittings and fuel screws

I have a 1998 VTR 1000 and I am currently getting 26mpg.

I had to clean my carburetors 3 times before I realized that the gas tank was contaminated, during that time I purchased the Ultimate kit from the carbjet kit website which consists of 180, 185 main jets, 48 pilot jets and 2 shims per carb $26. I recommend this website if you need to order jets.

I turned out the fuel screws to 3 turns, I know too far out. My bike has the stock air box and filter fitted with jardine slip ons. The bike runs terrific and the throttle is spot on but at idle it constantly stumbles around. I know the choke fittings are weak and I should have replaced them when I had the carbs off. I am hoping by fixing the choke fittings and turning the fuel screws in a turn I will be able to get closer to 30mpg.

I will post my results, maybe the info will help others.
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Old 08-27-2015, 10:28 AM
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You may find out your a little rich even with those settings.


Lately my gas mileage has ranged from a low of 30 to a high of about 35. I think I am slightly lean on the needles - might try an additional shim - I would have two shims under the needles if I added one.


Realize the fuel screws primarily affect idle performance. I wouldn't be afraid to try 45 pilot jets and lean the fuel screws out a little.
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Old 09-04-2015, 01:04 AM
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May be a tune up could solve the high gas consumption. Make sure to synchronized the TB.
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Old 09-20-2015, 07:22 AM
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I finally fixed my MPG problem. It turns out that 3 shims under the already tapered needle were way too much LOL oops.. I am back at 35 MPG
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