Carb problem-not spraying gas.

[Guest Ron Brown]

I fixed the starter clutch and started the bike with some difficult at half throttle so I put 6 ounce of redline in the tank. Now it will not start (hit) at all. Checked gas flow and it is working good and cleaned and checked firing of the plugs, Good. When I spray starter fluid in the carbs direct, it runs with the starter fluid and quits. I see no gas spray out of the carbs at all.

Edited January 20, 2013 by Ron Brown

[Kirby]

Ron, I'm not to familiar with the 1st Gens but they are not that much different from the 2Gens in design. The carbs on these bikes don't "spray" fuel. A vacuum is created in the carb venturi with the downward stroke of the intake and that in turn sucks fuel up out of the float bowls through various jets. Unlike certain "pumper" type carbs that spray down into the cylinders. If you think you may not be getting gas to the cylinders, pull out a couple of spark plugs and check for signs of wet fouling. If they are, then you definitly are getting some gas to the cylinders. If not, open the drain screws on the bottom of the carbs and see if some of the gas will drain out. If it does and isn't getting to the cylinders then you have probably got a problem with pilot jets being stopped up.

This is all said in the assumption that you have good fresh gas, it won't run at idle at all, it may run some with the throttle open, and all else (meaning electrical, compression, clean air filter, and timing ) is in good working order. Remember one simple thing, It takes 4 things for a gas engine to run: Gas, Compression, Ignition, and Timing! Keep us posted and maybe some of the others that are more versed in these bikes will chime in shortly.

[skydoc_17]

Hey Ron,

The First Gens. DO NOT like to run with the Air Filter Removed, or the Air Box Cover Off.

Try reinstalling the air filter, and the air box cover. If the battery has been sitting for a while, try charging it. Install a new set of plugs gapped properly, (it's impossible to tell if a plug is fouled with the naked eye) If your gas is over a month old, you may want to drain and replace it due to the Ethanol in it. Here is the cold start method I use on a bike that doesn't like to start.

 

1) NO Choke, do not touch the throttle, key on, wait for pump to stop running, crank for 10 seconds. If it fires, then shuts off, go to step two. If it doesn't start at all, go to step three.

 

2) Half Choke, do not touch throttle, key on, wait for pump to stop running, crank for 10 seconds. If it fires, let it "fast idle" for a minute or so. Then start to reduce the amount of choke, but keep the idle above 1000 RPM's. If it won't start at all, go to step 3.

 

3) FULL Choke, do not touch throttle, key on, wait for pump to stop running, crank for 10 seconds. If it fires, let it "fast idle" for a minute or so. Then start to reduce the amount of choke, but keep the idle above 1000 RPM's. If it won't start at all, then some Carb. Cleaning is needed. When you twist the throttle, you bypass the Idle Start Circuit in the Carbs. and basically dump raw gas in the cylinders, fouling the plugs.

 

Here is a write up I did a while back to clean a set of First Gen. Carbs. on the bike. This doesn't address every issue with a set of Carbs, and it doesn't replace a good Carb. rebuild, but may get the bike started if the Carbs. are "gummed up".

 

Cleaning First Gen. Carbs. On The Bike

I use this cleaning method to unstick a float needle that is causing the gas tank to drain when the bike is parked, or for a Carb. that is passing raw gas out of the overflow tube when the bike is running. This on bike cleaning DOES NOT address the issue of a Carb. Set needing a complete rebuild, (off the bike) and does not address the issue of AIR PASSAGES being blocked, and causing poor performance. These two issues require the Carbs. be removed from the bike.

With the bike on the center stand, and the engine off, I select the first Carb. I want to clean. You will be looking for the Black Plastic Carb. Drain Tube, and the screw that opens that drain. (Phillips Head Screw) You will need a small coffee can, or a coke can with the top cut off, (NO plastic containers) to catch the gas that will come out when you open the drain screw. Allow all of the gas to drain from the Carb. and have a look in the can for “floaters”. (solid particles) With a new can of Carb. Cleaner, insert the red straw in the end of the drain tube. I wrap the junction of the red straw, and the drain tube with a small piece of shop towel to slow the blow by. Press the button on the top of the can of Carb. Cleaner, and count to 3. Remove the red straw and let the cleaner fluid run into the coffee can. Move to the next Carb. and repeat. When you do Carb. #4, start over again, and do them again. I use up one can of Carb. Cleaner on the four Carbs. When the can of Carb. Cleaner is gone, retighten all four drain tube screws,

(CAUTION DO NOT OVERTIGHTEN THE DRAIN SCREWS) Turn on the ignition switch, (do not start bike) listen for the fuel pump to fill the Carb. Bowls and stop pumping, check the drain tubes and the overflow tubes (down in front of rear tire) for fuel leakage, move the can with the Carb. Cleaner/Gas mixture away from the bike, (or better yet, roll the bike out of the garage) and start the bike. (It may take a few short bursts on the starter motor, and you may need to choke it as well) Go for a ride and “blow the cobwebs out” (my personal FAV part) if this doesn’t solve your problem, then a “Carbs. Off Rebuild” may be in order. On a side note, I run 3 ounces of Seafoam in every tank of gas I put in my 87’and 89’VR because of the negative effects of the Ethanol in the fuel these days. Because of my shop here in South Central PA. I buy OEM parts direct from Yamaha, and share my discount with the VR.ORG members. It would be my pleasure to help you with any project you have in mind for your First Gen. VR.

Earl (skydoc_17)

[Guest Ron Brown]

I drained the Redline fuel line cleaner from the gas tank and replaced with seafoam and gas. I still have back firing but took a long needed ride today.

 

The one of four hose to the air chamber to intake is off and the hose to the air cleaner to crankcase air release chamber is missing.

[utadventure]

Ron-

 

Earl has given some great info!

 

When I bought my '86, it wouldn't idle, so the dealer mechanic adjusted it and brought it back. Come to find out, they monkeyed with the sync screws, not the idle screw.

 

Condor suggested I start at the beginning....back the sync screws out so that there was no adjustment on any of them. Next, reset the mixture screws to 2 1/2 to 3 turns out (turn them in, count the turns and record in case you need to return them to the current settings). Start the bike and sync the carbs. Take it for a nice ride and see if there is an improvement.

 

Good Luck!!

 

Dave

[jasonm.]

there are 4 carbs here. Thus syncing the carbs requires a carb sync tool. Not something you can do by "ear". Otherwise you are wasting your time.. Proper tools are important. The best carb cleaner I have used is Berryman's and Techron. Berryman's is best for quick cleaning. Everything else snake oil..this is the result of my 20+ years with Ventures.

Edited January 27, 2013 by jasonm.