83 VR only getting 100 miles out of full tank.

[gspullen]

Hello again

 

More trouble out of my resurrected 83 VR. I have tried my best to sync the carbs but the #1 carb seems to have a vacuum leak or something cause #2 carb just pulls all vacuum away. I made my own gauge using tubing and oil. Trying to do everything on the cheap until I have a better cash flow. Even now after syncing #3 & #4 carbs together then syncing those to the #2 carb I am only getting around 100 miles out of a Full tank of gas. Any and all suggestions would be greatly appreciated. I do have mechanical skills and tools just need to know where to start. Bike runs great and idles around 1000rpm. Just uses way to much gas. I might as well drive my 96 chevy corsica to work.

[GilbertHall]

One of the VR members sells 4 little nylon washers (I want to say .024") which sets the metering rod deeper in the jet (less fuel).I use to get 27mpg, once I installed the nylon washers, it jumped to 37mpg. On a side note, winter grade gasoline yields up to 10% reduction in mpg. Keep in mind, Gasohol absorbs moisture, water and aluminum = aluminum oxide

[utadventure]

A few things to look into, just in case.

 

Remove the air filter box and start the bike (it will run crappy without the air filter). Look down into the carbs and verify that all of the sliders are fluttering (moving). They may be sticking. If they aren't all moving, using a screwdriver, gently pry the sliders outward. Next, remove the diaphram covers on the carbs. Double check the diaphrams for holes or tears. Remove the sliders that might have been sticking and clean it up.

 

While you have the carbs apart, you can put in new washers to adjust the needles (suggested above). There are threads on the site about how to do this.

 

Put it all back together and reinstall the air filter & box.

 

Back the sync screws out and start the bike. It will run poorly.

 

Adjust the rpms to 1000 and do a sync.

 

 

Good luck!

Edited November 11, 2014 by utadventure

[van avery]

First thing I would do before you take the carb off is spray starting fluid around the intake manifolds and the YICS systems with the bike running. There are Orings below the intake manifolds that can and do go bad and you will have a vacuum leak. When you spray the starting fluid around the carbs and intakes if you have an increase in RPMs then you need to look for a leak in that area.

The little plastic washers were avaliable for Skydoc_17 .

[Neil86]

Before tearing into carbs.....what model is the TCI

you presently have in the bike (tag on cover 26H-xx or 41R-xx) and where

is the vacuum signal hose connected?

Edited November 11, 2014 by Neil86

[gspullen]

Neil86,

 

The TCI box says 26h-10. I'm not sure about the vacuum signal hose. I only have 4 rubber caps (one for each carb) for vacuum.

[Yammer Dan]

Dump a can of BerryMan's Chem Tech in it before you start tearing things apart. Less than 4 bucks at Wally World and does a great job of cleaning.

[Prairiehammer]

I'm not sure about the vacuum signal hose. I only have 4 rubber caps (one for each carb) for vacuum.

 

On the 1983 only, the Boost Sensor (vacuum advance) picks up the vacuum from a port on the number 2 carb body. There should be a vacuum hose running from this port to the Boost Sensor.

In the accompanying pic of the carbs, the vacuum hose in question has been cut off at the end of the nipple that is on the #2 carb.

Edited November 11, 2014 by Prairiehammer

[videoarizona]

No one has mentioned plug wires and plugs.

 

Pulled my plugs and wires today and replaced with new. The wires must have been original as they still had factory stickers showing what cyclinder number on both ends. Not many miles, 38K...but 1989 means 25 years. So I bet that will help my mpg!

Saved two plugs for spares...threw front two away as they were corroded on outside. All old plugs were gapped differently from .031 to .035. All had 145ohms resistance as well....

 

Easy to do with info on site....only #1 wire gave me fits on threading through the loom.\

 

Suggest you check plugs.

david

 

[cowpuc]

As always, TONS of good advice going on here.. Pulling the air filter, starting her up and watching those slides will tell ya alot about how its responding to the vacuum.. If you have a stuck a slide, I would be very careful using anything to pry it open - that slide material is pretty brittle.. Just use caution with them when prying on em.. You will probably find it necessary to pop the diaphram covers to get the slides out and get them to slide properly anyway - if you have a stuck one you may as well start by pulling the covers and use your finger inside the slide (along with carb cleaner around the slide) to get it to move.. Those slides should move freely with no stickiness..

On another note, you should look your carb overflows over very very carefully.. A sticky float valve can really fool ya and can dump a lot of fuel out as your traveling down the road.. Just check the ends of all the overflow tubes and see if you have dampness on them... Of course, ANY sign of drippage while sitting idling should NOT be happening..

[Marcarl]

#2 cannot pull all the vacuum away from #1. The manifolds are separate. I suggest that #2 and #1 are not sync'd. #2 is governed by the idle set knob, it's under the carb rail in between #1 and #2. Turn the knob out until the bike just about dies, then try to adjust the sync screw for 1 and 2. You may have to repeat this. 3 and 4 will be out of sync with 2 when you do this, so you might have to go to that side to help out. Or you can go back to basics: get a long, 12" plus, thin wire that will reach to the butterflies. By sticking the wire between the butterfly and carb body you can adjust the butterflies (with the sync screws)to be very close to the same. Once that is done you can now start a sync.

[Flyinfool]

:sign yeah that:

 

Since there is no vacuum on the #2 cylinder you need to resolve that first. The sync between #1 and #2 is most likely WAY off. You are probably running on just 3 cylinders. You should still be able to sync the carbs even if there is no spark to #2. Start at the beginning and figure out why you have no vacuum at #2.

[cowpuc]

Another quick thought for doing it on the cheap,,, start the bike up, let it warm for a couple minutes, put some spit on the tip of your finger - touch each pipe one at time with your damp finger (like checking a hot iron), make sure all 4 header pipes sizzle at touch (see if its even running on 4 at idle) - these engines are kinda sneaky, if your not use to em that can be running on three and an unfamiliar ear may not even notice it... Draggin a dead cylinder will certainly eat fuel and, could certainly show up on a vacuum gauge..

If ya got a dead one, do like VideoAZ mentioned, at least pull the plug on the dead jug and see if the plug is fouled... These little "D" plugs dont take to kindly to blackening from overfueling/choking..

[Neil86]

Neil86,

 

The TCI box says 26h-10. I'm not sure about the vacuum signal hose. I only have 4 rubber caps (one for each carb) for vacuum.

 

Good idea to verify the vacuum hose is hooked up as per Prairiehammers post. If the hose is not connected pressure sensor is seeing

zero vacuum and timing advance will be severely reduced causing poor fuel economy and power.

[Venturous Randy]

From your discription, it sounds like you have plug caps on the YICS ports. Your problems also sounds like one of the plug caps is busted. This would explain the vacuum/sync problems and poor running and fuel milage. This is the way I plugged my YICS ports and don't have th worry about them anymore.

http://www.venturerider.org/forum/showthread.php?86100-Plugging-YICS-ports&highlight=YICS+ports

RandyA

[Venturous Randy]

Another thing to check is the spark plug caps. They have a resistor in them that can get corroded.

RandyA