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Discussion Starter #1
Ok this is driving me crazy. I only get about 80 miles to the tank around town which is down from 120/125. Can't find a thing wrong and bike runs fine. Mech can't find a prob either. It seems to have started after I replaced a Cam Adjuster ( or soon after) Any ideas? ( bad when gas is so pricey)
 

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Was the tank removed? check hoses
Cam chains tight and adjusted?
Is the choke opening and closing?
Check plugs for richness (black, wet)

For a reference, I'm running 140 jets and get a consistent 58 mpg if I don't push it.
Good luck, it's these little things that can be a pain to troubleshoot.

DT
 

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Love My Baby
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Hey Brian, even 125 miles to a full tank isn't that great. That's under 40 mpg. Have you cleaned your system with seafoam? And since you say your mpg's have gone down since you changed your cam chain tensioners, you may have to adjust them better. I would think if they're too loose the drag could be wasting a lot of gas. Just a guess though.

For a reference, I'm running 140 jets and get a consistent 58 mpg if I don't push it.
DT
DT that's great gas mileage. I usually get 46-48 combined city/hwy, and about 52 straight hwy. Could I get better mileage re-jetting? I live in Ft. Lauderdale which is right at sea level.
 

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The Professor
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Ok this is driving me crazy. I only get about 80 miles to the tank around town which is down from 120/125. Can't find a thing wrong and bike runs fine. Mech can't find a prob either. It seems to have started after I replaced a Cam Adjuster ( or soon after) Any ideas? ( bad when gas is so pricey)
Is that with or without reserve?
 

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Concert connoisseur
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i can get about 125 without reserve. 51 pretty consistently and 58 if I baby her, so I pretty much get 51. your brakes or anything aren't dragging you back any are they?
 

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did you over oil the air filters? This will make the engine run rich.

I bet you have a fuel leak though. 80 miles per tank is really really bad. JMHO
 

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The Professor
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did you over oil the air filters? This will make the engine run rich.
I bet you have a fuel leak though. 80 miles per tank is really really bad. JMHO
Our carbs are CV Constant velocity, which means the fuel is metered by the amount of incomming air by the piston/diaphram assembly. If the filters are partialy clogged it would suffer in performance and not gas milage. You can have Wide Open Throttle but the piston may only open half way.

Just by switching fron 87 octain to 93 octain will cause a massive drop in MPG.
 

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DT that's great gas mileage. I usually get 46-48 combined city/hwy, and about 52 straight hwy. Could I get better mileage re-jetting? I live in Ft. Lauderdale which is right at sea level.
I jetted because I use EMGO (K&N style) air filters and glass packs for pipes (no restrictions). Note I did say if I don't push it. Riding the interstate at 70 + or -, and the mpg goes down quick.

If you're stock, no need to re jet.

DT
 
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Discussion Starter #9
Thanks for the advice guys! Cleaned the filters and changed plugs no change... No leaks...Only run 93 when I want a light cleaning...breaks are in good working order... Going to seafoam it and check the cam chains and cross my fingers. lol oh and rub a rabbits foot.Thanks again.
 

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HAWK
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This bike runs best on 87 octane, you only spend more if you use higher.
I have used 87 all the way to 104 and there is not enough power difference that the price is worth
 

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Experiencing the same issue. Only getting about 26mpg around town when hitting a lot of stop and go traffic. Brand new NGK plugs and wires (plugs only have 1,000 miles on them) on the her and they look good (not wet and back), brand new K&N air filters, Seafoam about every 3rd tank and screws turned out to 2 and 1/2 turns after marbling. :confused:
 

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Higher than 87 octane gas isn't going to clean anything, but can help carbon things up! If you wanna clean, use seafoam. Hmmm, no black or wet plugs and not running bad, but getting that kind of mileage, you sure your speedo is working right? Sounds like fuel leaking. No gas smells? That would be a lot more stop than go in stop and go traffic to get 26 mpg. :confused:
 

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Yea, it's gotta be leaking man! You should be getting 50+ mpg. Does your odometer readings make sense? Like read 20 miles on a 20 mile trip?

If no leaks and you're burning that much gas I bet you'd see some black smoke out the exhaust (rich). If it's a carb issue, chances are it'll be one, not both.

My tank developed a leak where the left mounting ear is welded to the tank. It'd seep gas and evaporate. There was only a tiny hint of gas smell when it leaked and only when full.

The bowl was cracked once too. Same thing, seeped gas. So that cylinder would always be dead after it sit overnight.

Gas will evaporate pretty fast. If the bike is outside, you may never smell it. In a garage, maybe/probably depending how big and ventilation.

Just some ideas.
 

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Yea, it's gotta be leaking man! You should be getting 50+ mpg. Does your odometer readings make sense? Like read 20 miles on a 20 mile trip?

If no leaks and you're burning that much gas I bet you'd see some black smoke out the exhaust (rich). If it's a carb issue, chances are it'll be one, not both.

My tank developed a leak where the left mounting ear is welded to the tank. It'd seep gas and evaporate. There was only a tiny hint of gas smell when it leaked and only when full.

The bowl was cracked once too. Same thing, seeped gas. So that cylinder would always be dead after it sit overnight.

Gas will evaporate pretty fast. If the bike is outside, you may never smell it. In a garage, maybe/probably depending how big and ventilation.

Just some ideas.
Speedometer and Odometer are both working correctly, the bike is kept outside and covered ( I live in an apartment complex ) and never really smell gas and the gas gauge doesn't move from it previous spot when sitting over night so i don't think it has a leak and no smoke coming out of the exhaust.

Can't afford to take it to someone because I'm currently unemployed and my weekly benefits just went even lower because the DOL said my claim expired and I had to file another one, drawing off a company I only worked at for a month, so I just went from $330 a week ( $277 after taxes ) to $55 a week. :doh:
 

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Love My Baby
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You really should fix this problem now, because you're spending double what you should be on gas. $55 a week is not enough to allow you to waste money on a gas leak or whatever is causing you to have such poor gas mileage.
 

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Not sure what I can do. Lance is the only one close by that could help me figure out what's going on that would probable cut me a break on time and labor until I can find job, but he's a busy man these days.
 

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Surely you can figure it out. The VN750 isn't a complicated bike.

I'll just say a leak one more time: If the fuel gauge doesn't move when you park it just means the leak is probably not in the tank. The diaphram cuts gas until the engine's vaccuum pulls it open again.

Anyways, tell us anything you can about the bike.

When did this start?
Did you change anything around that time?
Does the engine run smooth and strong?
Does it idle properly?
Do you have to use the choke to start the cold engine?
Are the brakes overly sensitive?
Do you hear the brake shoe/pad to metal when you ride?
Any noises coming from the wheels? Grinding? High pitched that might be a bearing?
What gas do you run?
Any pinging from the engine, or under load?
Does one pipe sound different than the other?
Check the differential oil level.
What's your engine RPM at 60mph?
etc...etc....

I dunno if it's any comfort: Yea, you're getting bad MPG for a bike, but 26MPG is still pretty decent for a car, so it's not like your burning a LOT of extra money. Granted it needs to be fixed, especially on $55 a week. Ouch.

Unless I know someone I can trust, I think I've always regretting taking my vehicle to the mechanic. But that said, sometimes I've regretted fixing it myself too. HA!

Let me know when you've heard enough. I'll shuddup. :blah:
 

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Surely you can figure it out. The VN750 isn't a complicated bike.

Anyways, tell us anything you can about the bike.

I dunno if it's any comfort: Yea, you're getting bad MPG for a bike, but 26MPG is still pretty decent for a car, so it's not like your burning a LOT of extra money. Granted it needs to be fixed, especially on $55 a week. Ouch.

Unless I know someone I can trust, I think I've always regretting taking my vehicle to the mechanic. But that said, sometimes I've regretted fixing it myself too. HA!

Let me know when you've heard enough. I'll shuddup. :blah:
When did this start? Has been this way ever since I bought it from the PO.

Did you change anything around that time? Since I bought it I have - Changed the oil once myself ( currently running 10W40 ), changed the final drive oil myself, had the Kawa shop do a 20,000 mile service on it, cleaned the carbs myself, bought new tires, bought new spark plugs, bought new plug wires, rebuilt the ACCTs, marbling trick, turned the screws out 2 1/2 turns and just bought the K&N stock replacement air filters.

Does the engine run smooth and strong? Engine runs good

Does it idle properly? Idles like it should

Do you have to use the choke to start the cold engine? Yes

Are the brakes overly sensitive? No

Do you hear the brake shoe/pad to metal when you ride? No

Any noises coming from the wheels? Grinding? High pitched that might be a bearing? No

What gas do you run? 87 octane, seafoam every third or fourth tank.

Any pinging from the engine, or under load? No

Does one pipe sound different than the other? No

Check the differential oil level. I'm guessing you're talking about the final drive oil, it's fine.

What's your engine RPM at 60mph? Runs about 4000RPM

The PO had inline fuel filters and a new petcock installed 5,000 miles prior to me buying it from him.

Not sure if the PO did it or the PO before him, but the tank has been kreemed.

Anything else you need to know? lol
 

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Dang.

I'm at a loss. Thanks for putting up with the questions. It would have been awesome to help a guy out.

If it were mine, I'd replace all the engine vac and fuel lines ($5), run the tank dry and drain the carbs, fill it with 93 octane BP/Amaco gas ($8), pull the air filters off and ride a tank of gas through it. I'd probably pull the fuel filters off when you replace the lines.....then splice them back in after this test.

I honestly don't have any other ideas, sorry. And I say BP/Amaco gas because I've never, EVER had a problem with the stuff. My high compression Ford could always tell the difference.

I hope something I said helps.
 

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Old Truck Junkie
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You could be getting a little bit of fuel going past the valve and seat.

Another way that happens, but very rare is that if the seat is loose it will leak around the seat throught the threads.

A third place that fuel can get past the valve is through the vaccuum hose to the petcock.

And some have mentioned some diaphrams in the carb itself, I am not educated enough on the carb to know which ones.

Hope you find your problem.
 
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