only getting 25 mpg!

[moscar45]

Hey guys, I know I'm bigger than most riders (335 lbs), but should that be killing my fuel mileage that much? I only got 125 miles out of the last tank. I use premium fuel, and don't ride it like I stole it. 100 out of those 125 were cruising, not in town. Bike has a vance and hines full header exhaust. I'm not sure what the jetting is...bought is not too long ago. 1991 kat 750.

[monolith]

Ok...per the Kat service manual shown here....Post Kat 750's only pull 38 mpg with a full tank range of 150.....The 750F's pull a little more...

With mods, the age of the bike, and your weight....I'm 250...not a small rider myself ...I'd say thats about right...

[moscar45]

Wow, I definitely expected more than 25mpg. The bike just turned 7k mles. Still fun though.

[scottynoface]

You're wasting your money with premium fuel. You're a big heavy dude, the bike is old, and the bike is carburetted. Also has a full exhaust system and if so, should also have bigger jets in to pump more fuel so the bike will run correctly.

All of these are working against your fuel mileage, but 25 is still kinda bad...

[diavolo]

Several things will affect your mpg - check your tire pressure - make sure you aren't trying to "push" the bike instead of roll. Oil level good? Does the bike have a jet kit? (that will drop your mpg's). Level of tune?(firing on all 4, have the valves been adjusted, etc).

[Nero]

All of what Diav said.

[Frenchcropper]

I would add chain health.....

[The CyberPoet]

I think something is wrong... at 400 lbs with rider+passenger+cargo load & saddle bags, running triple-digit speeds, I still got about 29 mpg out of the Kat...

My first instinct is to say there might be a fuel float in the carb stuck open, leaking gasoline into the engine (check your engine oil level -- did it go up? also check your airbox -- any fluid inside?).

To get that bad a mileage out of just low tires, bad tuning and bad chain/sprockets is virtually unheard of at normal interstate speeds...

Cheers
=-= The CyberPoet

[Pacerman]

On my 2001 750 i got right at 200 miles on a tank. Then I put a yoshi slip on, K & N and dynocrap jet kit in and it went down to like 145 to 155.

So i went from 40 MPG to about 30MPG. I weigh almost 200

[md86]

Or gots a leak ....

[Kreylyn]

Per my last 6 ride averages, each running a near full tank out...

44.4 mpg, using stock jetting but up 3 teeth on the rear sprocket. I've lost about 7mpg with my sprocket change... but then I also find myself getting a little more "rambunctious" with the curves now as well.

Gonna be hell when I instal the jet kit I think...

If your getting 25mgp, I would guess you have a leak going on. Check for damp spots under your tank. Check your drain hoses off the petcock and vent lines to make sure they are not letting gas out. (My wifes ninja rusted out on the over flow tube, and allowed gas to pour out of it if filled more than 2/3 full.)

If nothing there, then you may have a sticking or leaking float needle. Extra gas could be getting dumped and blown out the tail pipe. If you do not loose gas when sitting, and your petcock is working, this would be a likely scenario.

Krey

[Arstine]

Been said already but I have to say it again, I would absolutely look in to the carbs. I have a 92 1100 that pulls 35mpg. It's even got 38mm Mikuni RS' on it and a Yosh header/pipe and it's jetted a little fat for the altitude here. I figure with tuning I could pull another 10mpg out of it. So if you are only getting 25 there is no doubt that something is mechanically wrong there.

[moscar45]

Thanks for the input guys. I've checked, and I can rule out a leak. Petcock is newly replaced. I have not checked tire pressure. On my last 2 rides, I have noticed that the bike is a little more "sluggish" than I expected, and after a two week sit, I had a little noticeable engine noise on the last ride. I highly doubt I have a serious problem, but maybe it is the valves that are making the excess noise. I am guessing I need a suzuki tech to check it out. The bike really is cherry......so much so that I put off buying the brand new b-king I planned on getting after using this bike to knock the cobwebs off my riding skills. I doubt the carbs have been rebuilt with 7k ont he odo. The previous owner (mambopalace int he for sale section) replced virtually every wear item.....except attending tot he carbs since he thought they were god. He did not put more than a few miles ont he bike during the restoration if you can call it that. Should I put off riding it until I get it checked out?

[kevin2502000]

If it's not leaking and doesn't have gas in the oil, andit runs good, ride it like you stole it!

[md86]

Yeah , but 25mpg ...... Like I always seem to say , "what do the plugs look like?"