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Discussion Starter #1
Hi all, I'm interested in getting some opinions on fuel economy. I have a recently restored 86 GSXR 750 that had some serious carb mung. Cleaned up nicely but after going through my first tank of 94 octane I only got about 225Km(140mi). I really hoped for about 400Km(250mi) per tank. I assume the tank is about 4 gallons. All riding was in town and very light on the throttle. Does that seem to sound normal? Exhaust does smell rich at idle.

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'86 GSXR 750. Stock. On the restore.
 

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250 miles out of 4 gallons is more than 60 miles per gallon. that's a bit too much to expect, even with totally stock carburetion (which is on the lean side).

if we assume that the main tank (i.e. not including reserve) is about 4 gallons, you're getting about 35 miles to the gallon....which to me sounds about right.

are the carbs jetted? that would tend to reduce fuel economy...


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i had individual filters and stage 3 jetting on my 85-87 750's.....they got less than 30 miles a gallon....

so i'd say what you're seeing is about right.


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I've got an 88 750. Every 200 km I put in 10 bux (89 octane at 75-80 cents). Or 200k uses 11 litres about

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keep it rubber side down....
 

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Discussion Starter #5
No jetting as far as I can tell. It has the original 97.5 main jets and I'm sure stock idle jets(can't remember size). Plugs are burning nice and brown and I'm running a stock airbox(may be leaking). From what Cosworth wrote he's getting about 50% more distance per unit of fuel. Hmmm, will have to do some more investigation. Perhaps the clutch slipage, incorrect chain tension and some brake drag were factors too. It all adds up in the end. Thanks for the help.

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'86 GSXR 750. Stock. On the restore.
 

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On my '87 with stage three's I get about 100 miles of HARD riding before I hit reserve with 138 mains in it..135 miles on a tank.then I threw on a set of Keihin 39 mm flatslides and I get about 150 total now...the keihins atomize the fuel better...and they have 160 mains in them.

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Discussion Starter #8
Hey Cos, I see you run the stock airbox, what size mains are you running? Are they vacuum or mech in 88?

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'86 GSXR 750. Stock. On the restore.
 

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Sorry B-man, I inherited the bike like this from the International bankruptcy sale and have not had it apart yet. It is jetted, K&N, yosh pipe etc. with 106 bhp. http://24.113.193.215/bike/dyno.jpg
I am a short shifter though. No idea what my Mikuni's have installed.

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keep it rubber side down....
 

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Hey Jeff, remember he's probably talking Imperial gallons. If I remember correctly, 6 US = 5 imp...or something close to that.

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