Update on Gas Mileage

[Freebird]

I posted this last night but accidentally posted it in the read only tech library, sorry about that.

 

I mentioned a while back that my gas mileage has gone way south. This started over a year ago, long before installing the VMAX rear end. I recently changed the plugs, removed the K&N filters and tried stock again and neither of those things have helped.

 

Today I will remove the Dyna 3000 and re-install the stock ignition module. Now the Dyna did not originally cause the problem but I'm just trying to rule out that something might have gone bad with it.

 

Bike runs good, idles smooth, has great power. This is really baffling me. There is no fuel overflowing that would indicate a stuck or high float. So...I'm still looking.

[pegscraper]

Just how bad is your gas mileage? My vote is for a carb problem. Have you checked them out at all? I wonder if it's possible for a throttle valve to stick open. Usually they stick closed.

[Eddie]

Solution: Part it out on ebay and buy new bike .

[Freebird]

I checked it last weekend after changing the plugs and filters and got a whopping 26 MPG. I use to get in the high thirties and low to mid 40s, depending on the type of riding I was doing. Now I have added the speedo healer so with that odometer correction there would be a 7.5% loss but this problem started long before I added the speedo healer.

[pegscraper]

Before you pull the D3K out, you might check out what the LEDs are showing. One of them, I forget which one, should come on when the throttle is about halfway open. Or maybe it goes off, I don't remember. The status of it should change at about half throttle. I'll put it that way. If it doesn't, it indicates a problem with the TPS somehow, maybe a connection that got dirty. I know firsthand that if the TPS is not connected or doesn't work right, that gas mileage will be in the mid to low 20s. Spark advance can make a big difference in gas mileage.

[Guest KitCarson]

I posted this last night but accidentally posted it in the read only tech library, sorry about that.

 

I mentioned a while back that my gas mileage has gone way south. This started over a year ago, long before installing the VMAX rear end. I recently changed the plugs, removed the K&N filters and tried stock again and neither of those things have helped.

 

Today I will remove the Dyna 3000 and re-install the stock ignition module. Now the Dyna did not originally cause the problem but I'm just trying to rule out that something might have gone bad with it.

 

Bike runs good, idles smooth, has great power. This is really baffling me. There is no fuel overflowing that would indicate a stuck or high float. So...I'm still looking.

I would not suspect the ignition module, not always, but usually they act up in other ways, missing, lack of power, a few hic-ups, or bike is just dead. That kind of high usage of gas, is for sure a carb situation, you have mentioned you do not smell or see gas, at idle, choke is okay? Not partially closed? I would think you have some type of blockage in one of the carbs, creating a vacuum at speed, acting for the best way I can explain, like a closed choke and as a gradual and steady overuse of fuel........even on of the jets could have vibrated loose, that is a tough one, you will not really know till you open them up and investigate. Hey I have to wear reading glasses now!! Good luck, something goes wrong with mine, I think I will hire a young mechanic, all those little parts and springs..........gee!! Take care , Kit

[BOO]

I have always been amazed at the difference in gas mileage that people have. I've pretty much always got in the upper 30's with the Ventures I've owned. First and second gens.

Some have reported in the mid to upper 40's and I've wondered how they were able to do that.

So the bottom line from me is I can't help you but I would be really interested in what the problem is when you get it corrected.

Have you thought about hooking the AIS unit back up just for grins?

I can't imagine it would have anything to do with the mileage but you never know I guess.

Good Luck

Jerry

[Freebird]

I just don't see the AIS being a problem. Heck, mine has been plugged since 1999 and then completely removed in '05. It never affected the mileage.

 

I will check the LEDs for the TPC and last case scenario, I will pull the carbs this winter and go through them.

[Eck]

With bike up on jack, wheels off ground, see if there is a drag when turning the front or rear wheels...

A bad or binding wheel bearing, sticky brake caliper, anything that would OLD YOU BACK..in a sence..

It may not have anything to do with the running of the bike, but something holding it back..

[Squeeze]

Loose Main Jet maybe, or TPS/Spark Advance Problem. Also worn Floater Valves could cause such Problems. Of Course also, what Eck said, slightly sticking Brakes, weak Wheel Bearings ...

 

 

Friend of mine has had the LockScrew in the Slider getting loose, the Needle did fall out of Place and this Cylinder did get almost full Fuel all the Time. Only noticable Thing was a Drop in mpg.

[Stoutman]

You didn't mention how the plugs looked. How did the plugs look in relation to each other? Is one of them is a darker color? Do they all look out of whack? How was the gap in relation to when you put them in? I'm sure you looked at this, but you didn't say in your post how they looked.

[Freebird]

The plugs actually looked good. Gap was fine and color was good and also consistent between them all.

 

I got around this morning to checking the LEDs on the Dyna 3000 and according to them, it is working fine. TPS LED lights up at 50% throttle position as it should. According the LEDs, it is operating properly. I'm pretty sure that the Dyna is NOT the problem but I may try the stock one anyway just to completely eliminate that possibility.

 

So...coils are good, plugs are good, air filters are good, Dyna appears to be good. That leaves me with carb problem or mechanical resistance. I'll put it on the lift today but I'm sure that's not the problem. I've had it on the lift a number of times and always spin the wheels and etc.

 

Sure looks like a carb problem and carbs, other than synchronizing, are NOT my specialty. I guess I'll pull them over the winter though and see if I can find anything.

[Redneck]

It sounds like a carburetor issue to me also but you may want to check your valve adjustment as well.

[BuddyRich]

Gained any weight lately Don.

 

Didn't you change to the RSTD pipes about a year ago?

Check compression. Easyrider was getting that kinda of gas mileage on his first RSV after they rejetted the carbs.

[Freebird]

Yes, I did change to RSTD pipes but as far as I can tell, they are identical to the stock RSV pipes with the exception of the tips.

[BuddyRich]

I'm running them too. Drilled out and with stock Filters. Usually around 36.

Try premium for a couple of tanks.When we left Ft Collins there were a couple of times the Rav4 dropped to like 10 miles a gallon. Started running Premium and did not have that problem. Maybe its the gas.

[Gem Setter]

SEAFOAM IT!!!!!!

[Freebird]

I've tried all different grades of gas and have SEAFOAMED the heck out of it.

[Al Bates]

Check your carburetor fuel vent lines. It's a small rubber hose, looks like a vacuum hose. There is one on each side. The left two carbs are on the left side and the right two carbs are on the right side. Both are behind the air filters. (hidden) I pulled them out and place them just under the air filters so I can monitor what is going on. (check pic's below) If there leaking fuel sometimes you can smell it. If you can see them you can monitor them. If there is any fuel coming out of them, mostly at idle, there's a problem. It's running rich.

Low fuel mileage.

 

THE FIX: Pull the spark plugs. Check and see which plug is running rich, if that is the case the plug will be wet and black. Fine out watch plug = carburetor and change the needle and seat, check the float level.

[Al Bates]

Sure looks like a carb problem and carbs, other than synchronizing, are NOT my specialty. I guess I'll pull them over the winter though and see if I can find anything.

 

 

1. Some things to remember when overhauling the carbs.

 

2. Disassemble one at a time.

 

3 . Remove every part that can be removed.

 

4. Be super careful with the o rings.

 

5. Take your time and clean each part. (kerosene, carburetor cleaner, etc)

 

6. Do a good inspection on all the parts.

 

7. Use compressed air to dry them off and blow through each passage way.

 

8. Reassemble with NEW needle and seat, check the float level and make

adjustments as needed.

 

9. Use petroleum or vaseline for reassembling, (makes it so much easier)

especially the diaphragms and O-rings. Once there out sometimes they

swell and hard to reinstall. Put (load) petroleum or vaseline in the grove

and on the diaphragms edge, use your fingers and thrums and lightly press

the edge of the diaphragm into the grove. The petroleum or vaseline will

keep the diaphragm in the grove. Carefully install the diaphragm cover.

 

10. Reassembling the chock is a little tricky.

 

11. Adjust idle and Synchronize carbs.

 

12. Check the carburetor fuel vent lines. Should have no fuel coming out of

them.