JohnnyG383
Member
I'm sure there have been posts like this before but I just do not get it and could use any help to figure out this problem. I got 26 miles to 5 gallons of gas and 55 miles to almost a whole take maybe a gallon left in the tank when the ride was done. Also notice the engine seems to have not mid range power kinda feels like it breaks up. But when you go wide open it takes off like a rocket. and also you have to give it a lot of gas to get moving. My friend I ride with has a 2003 Viper 700 and on the same ride he used one bar of gas I don't get it. I also change out the plugs with new ones on a stop on the ride did not seem to make any difference.
super1c
Super Moderator
You won't even come close to that viper in MPG. Maybe 10 at best. Almost sounds like your chokes stuck open. Using a lot of oil also?
shaggyzr2
Active member
The 500 twins don't get the best mileage but that sounds pretty bad. I just got back from riding a 99 vmax deluxe 500 twin, I figured I used about a quarter tank in about 30 miles running the sled pretty hard.
JohnnyG383
Member
I'll check the carbs but the way it runs wide open I do not think the choke is on and it idles nice. Plugs I took out were pretty black also. It seems to use the normal amount of oil I know it's adjusted right the two lines are lined up on the oil pump at wide open throttle.
JohnnyG383
Member
Does anyone know how bad the mileage is on a 97 600 Vmax? My uncle has one he does not use anymore I'll buy it and sell this one if I can't get any better mileage out of this one.
shaggyzr2
Active member
I'd say mileage mileage between 500 and 600 twins would be about the same. If you want better fuel mileage get a triple.
Unless you were riding strictly off-trail your sled has issues. I would just go through the carbs and the rest of the intake. Make sure the engine itself is fine. The check your clutches. You are not just slightly off but quite a ways off good tune.
shaggyzr2
Active member
If your clutches are worn and or not aligned that will eat up gas. Also check track tension, being too tight will suck more gas. check your idler wheel, jack shaft, and axle bearings too, if they don't roll smooth it takes more power to move them which will take more fuel.
JohnnyG383
Member
Thanks for the tips guys I just installed a new Yamaha Belt and checked the track everything runs smooth and I set the belt deflection as stated in the tech page. This sled from what I was told by the guy I bought it from it was sitting a long time since a guy bought it new and cracked it up a little and parked it to sit for a very long time. The guy who I bought it from said it bought it at an estate sale and the sheld it was sitting it did not have a roof on it anymore. The guy I got it from put a new seat cover on it and said he changed the speedometer because it was broke but it did not work when I got it still did not work that's when I fixed the drive in my other post. He told me the sled had like 100 miles on it when I got it I do not know if I can believe that the speedometer in it says 5,400
shaggyzr2
Active member
what size jets are in the carbs and what are the needles set at?
JohnnyG383
Member
Everything would be factory stock.
shaggyzr2
Active member
I'm thinking something isn't right with your clutches.
JohnnyG383
Member
Everything would be factory stock.
Schocker65
New member
I have a '99 V-Max deluxe which has essentially the same powertrain. I have not been on it enough to actually check the fuel mileage, but it behaves in a similar manner and seems to go through gas like crazy. I just rebuilt my clutch to stock components but have only been able to lap around the yard that way. Still seems to need a lot of throttle to get moving and to maintain relatively low speeds, which I believe leads to the crap mileage. Like yours, when given the whip, it takes off like a scalded cat.
These sleds have a reputation for being thirsty. I think the problem lies in the clutching, unless the motor really just is very low on midrange power and inefficient when it's not yet "on the pipe".
These sleds have a reputation for being thirsty. I think the problem lies in the clutching, unless the motor really just is very low on midrange power and inefficient when it's not yet "on the pipe".
JohnnyG383
Member
That is how mine is takes a lot of throttle to get moving and seems to have no mid range power yes were I ride in Vermont it's a lot of trail riding slower speeds and the kind of riding that you need mid range power for when I try to run it not wide open and in the half throttle range the engine seems to be choppy and not smooth and not a lot of power until I give it enough throttle to get the power band in and it takes off. If the carbs are in stock settings what would be the jets sizes and mixture screw & needle settings.
BornYamaha
Member
These engines are peaky. They are pulling over 90 hp out of 494cc with no power valves. That is about the same hp/cc ratio as the old srx440s. There is an old dyno chart floating around here somewhere that shows this. Very soft midrange. Not a bad sled for kids for this reason. Mpg has always been terrible. 6 to 9 in my experience but our 98 has been in the family since new with over 10,000 miles almost trouble free so that is worth something. Your mpg does sound excessive. Triples are the only way to go for mpg. 14 mpg is the norm.
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Are your sliders burning?
JohnnyG383
Member
I do not believe so but what is the best way of telling if they were?
Bad reeds, mis adjusted floats, needles set too high.
JohnnyG383
Member
I'm going to check the reeds I just ordered gaskets for them. and go through the carbs thanks! is there a places where I can get all the stock carb settings for my sled?