Latest on my 89VR tinkering

[BlueSky]

My bike has been running rich since I bought it a year ago (with 5,914 miles on it). And the idle mix screws were only one turn out from bottom. I recently switched the gas valve to reserve and rode it to Skid's meet at Hamburger Joe's. It missed a little on the way back. So, I put a half bottle of Gumout for high mileage engines in a tank of fuel and rode it about 25 miles. It started running really ragged and the fuel filter had black gas in it when I checked it. After sitting overnight, I rode it about 20 miles the next day and it ran better. The next day I ran the tank out and it ran fine the whole time. Then it sat for a week while we went on a cruise and ran ragged again when I rode it after returning. The fuel filter now has clean appearing gasoline in it. I just received a new filter to change it out with. So, yesterday I replaced the spark plugs that were really black with soot. They were NGK DPR7EA 9 plugs and may have been the original plugs. The new plugs are NGK DPR8EA 9. Now it runs great again. I think it is still running rich and I turned the mix screws to 1/2 turn off the bottom. It starts instantly and runs great with just a tiny bit of occasional hesitation when I roll on the throttle from 3K rpm or below. So now the plan it to check the fuel level in the carbs and I think someone mentioned that the fuel enricheners could cause a rich condition.

 

Any other ideas for what to check/adjust without taking the carbs off?

Thanks!

Edited June 10, 2015 by BlueSky

[BlueSky]

I just rode to Home Depot to pick up a couple items and when I got back, I adjusted the idle screws. I turned them in until they bottomed (from 1/2 turn from the bottom) and the engine gained rpm when I screwed in each of the four idle mixture screws. It went from idling at 1000rpm to idling at 2000rpm when I turned all all of the screws in. So, something that isn't supposed to is providing fuel at low rpm. WTF

[cimmer]

I would look at a carb sync also as I bet they are out of sync with each other and that can effect how it run also. If you havent checked the diaphragms yet, I would pull them and see if they have holes in the rubber section, and if so they will most likely need to be replaced.

Let us know how it goes..

Rick F.

[BlueSky]

The sliders appeared to be working well when I checked them. All four seemed to be working in unison. Tomorrow I'll check the float levels using the tygon tube as directed in the manual.

[BlueSky]

Okay, I just checked the fuel levels in all four carbs using the procedure outlined in the manual and they are set correctly. So I can rule out that potential problem. By the way, my 3/8" tygon tube (1/4"inside) fit snugly over the drain tubes, tight enough the connections did not leak.

 

The only other thing I can think of to check is the enrichening valves. Is there anything else that can cause it to run so rich?

 

By the way, when the engine is idling low, it occasionally makes a popping noise??? It's almost a metallic sound.

Edited June 11, 2015 by BlueSky

[BlueSky]

Okay, the latest flubup! When I turned the idle mix screws (pilot) in to the bottom and the engine revved high, I made the dummy mistake of adjusting the idle using the wrong screw. I turned the screw that syncs the #2 carb with the #1 instead of the idle stop! So, now I have to sync the carbs. Luckily, my wife asked me what I wanted for Christmas last year and I said a CarbTune and here is the link. So, I have the tool to fix my flubup.

 

Another thing, after the de-sync flubup, I rode it around the neighborhood and of course it wasn't running that great. When I slowed to almost a stop to make a right turn, the engine shut off and I almost dumped it. I was still moving turning to the right so I turned the handlebars all the way to the right and it was moving enough to help keep from losing it. I was lucky!!!

[BlueSky]

Actually it was the Motion Pro unit, manometer, and it is a POS. When I tried to use it, air bubbles kept forming in the tubes. The fix for that it to shake them down like you shake a thermometer down. Doesn't work very well. What a piece of junk. I shook them down taking a lot of shaking and tried it again only to see more bubbles form. I may have contributed to the problem by bringing it into the house to assemble and read the instructions where it is 77 degrees and then took it out to the garage to use it in 93 degree heat. Anyhow, I see myself trashing this junk and buying a gauge set or maybe I'll just get some tubing, manifold, and some tiny valves and use my vacuum gauge. I should have bought a mercury unit back when they were available. I left it hanging in the garage. I'll give it one more attempt tomorrow. Returning it 6 months after purchase is not a possibility I suppose.

[cimmer]

The issue with the Motion Pro unit is that the o-rings dry out and dont provide the proper seal. They sell a refill kit of the fluid and seals but I gave up on mine also as I replaced the seals and such and then next year it was doing the same thing. I ended up buying a Carbtune and havent looked back since. It works great and nothing to spill out of it.

Rick F.

[BlueSky]

This guy built a neat sync tool for two carbs. The same thing could be expanded for four.

 

http://www.instructables.com/id/DIY-DualTriple-or-Quad-Carburetor-Sync-Tool/

[BlueSky]

I tried again today to get the bubbles out of the Motion Pro POS and failed. I called Motion Pro and was told I probably didn't have enough fluid in it. Seems it evaporates and even though this is the first time I've tried to use it, it may not have enough fluid. He offered to send me a refill kit if I provided info on the device, where it was bought and the serial number.

 

In the mean time, I think I will make my own. I'll use a clear plastic 2 qt nut jar with a Plastic top. Put a qt of so transmission fluid in it. Drill 5 holes in the top, one for a vent. Stick 4 long clear tygon tubes in the jar to the bottom. Mount it on a vertical 2x4 with a base and it will be ready to use. No freaking calibration needed.

[Donvito]

Here's a picture of the one I made. Works great.

[BlueSky]

I made a carb tuner somewhat like Donvito's unit and finally got the carbs synced. I attached a photo below. it took about 50' of tygon tubing and 2 tees from Home Depot. The trans fluid, wood, nails and staples I had laying around the garage. After my mistake, they were so far out that I had to be careful not to suck fluid into the engine. Eventually though, I did get them synced.

A manometer is only good for the final tune it seems. If the carbs are way out, the engine sucks the fluid into the manifold. If I buy another carb sync device it will have 4 gauges and definitely won't be a manometer. I called Motion Pro about that unit and they said it needed fluid and I should buy a refill kit. The guy was mainly interested in finding out who sold it to my wife on Amazon and if they were an authorized dealer. They were not according to him. He suggested I not buy discounted units from unauthorized dealers on Amazon or ebay. So, if anyone is interested in a genuine Motion Pro unit that needs a $6 refill kit cheap, let me know.

 

[BlueSky]

This week, I removed all four pilot jet screws with the springs, washers and O-rings. After unscrewing them, I put a touch of gasket sealer on the end of a small allen wrench to pull the screw out and then used a pic to retrieve the springs, washers, and O-rings. It appeared that one did not have an o-ring and another did not have a washer. I bought some new pilot jet screw kits from partzilla ($5 something each) and replaced the missing washer and o-ring. Then I changed the fuel filter. That was a first time for me and definitely was a learning experience. I'll do it faster next time. I cut open the old filter and it was clean inside. I thought it would be plugged up after the half bottle of Gumout for high mileage engines turned the gas black for a while. The engine is not running right still. I think I will ride it some and see what happens. If it doesn't improve, I think I will change the spark plugs again. Maybe one of these years, I'll get it right.

[syscrusher]

I have to laugh at the 6 foot tall boards with the tubes hanging off of it.

 

Take a look at this. With the newer, cheaper sources for parts this is really the best solution.

It takes about an hour or so to solder and assemble it all.

There is no liquid to fret about and a higher level of accuracy can be achieved.

 

http://www.venturerider.org/forum/showthread.php?95616-Hey-check-out-this-digital-carb-sync-that-I-used-to-tune-my-1st-gen-today!

[Venturous Randy]

I just rode to Home Depot to pick up a couple items and when I got back, I adjusted the idle screws. I turned them in until they bottomed (from 1/2 turn from the bottom) and the engine gained rpm when I screwed in each of the four idle mixture screws. It went from idling at 1000rpm to idling at 2000rpm when I turned all all of the screws in. So, something that isn't supposed to is providing fuel at low rpm. WTF

 

I think it is general consensus that most on here run the fuel mixture screws from about 2 1/2 to 3 turns from bottom. I am not sure what running all four at 1/2 turn from bottom would do. Another thing to keep in mind while syncing carbs is that if you have any manifold leaks, you are then trying to sync that leak into the balance of the carbs. I would get some starter fluid and spray around the manifolds and carbs and if you have an RPM change, you may have found a leak.

Another thing I have done is to drain the carbs and with the drain valve open, with the little tube, I have sprayed carb or brake cleaner into the small jets down into the tops of the carbs. I believe this will backflow through the pilot jets, not fuel mixture screws, and may break any blockage loose. If you have any pilot jets plugged or even partially plugged, it will have a big impact on how the bike runs, especially at lower RPM's.

Randy

[BlueSky]

I think it is general consensus that most on here run the fuel mixture screws from about 2 1/2 to 3 turns from bottom. I am not sure what running all four at 1/2 turn from bottom would do. Another thing to keep in mind while syncing carbs is that if you have any manifold leaks, you are then trying to sync that leak into the balance of the carbs. I would get some starter fluid and spray around the manifolds and carbs and if you have an RPM change, you may have found a leak.

Another thing I have done is to drain the carbs and with the drain valve open, with the little tube, I have sprayed carb or brake cleaner into the small jets down into the tops of the carbs. I believe this will backflow through the pilot jets, not fuel mixture screws, and may break any blockage loose. If you have any pilot jets plugged or even partially plugged, it will have a big impact on how the bike runs, especially at lower RPM's.

Randy

 

When I bought the bike last year, the mixture screws were set at 1 turn off the bottom. The bike ran okay but it was running rich evidenced by the fact that it would start without choke and I could smell raw gas after starting it and letting it run at idle. I'm trying to figure out why it is running so rich. I tried turning the mix screws out to 2 full turns off the bottom but when I rev it up and let off, black smoke comes out the exhaust indicating super rich fuel mix.

[BlueSky]

I have to laugh at the 6 foot tall boards with the tubes hanging off of it.

 

Take a look at this. With the newer, cheaper sources for parts this is really the best solution.

It takes about an hour or so to solder and assemble it all.

There is no liquid to fret about and a higher level of accuracy can be achieved.

 

http://www.venturerider.org/forum/showthread.php?95616-Hey-check-out-this-digital-carb-sync-that-I-used-to-tune-my-1st-gen-today!

 

That device looks neat but sounds like I would have to build it. The funny thing about the manometer I built is that it needs to be 30 or 40 feet tall to prevent the engine from sucking the fluid into the intakes if the carb sync is way off. That is why I won't be buying another manometer of any brand. Anybody want a Motion Pro cheap?

[Flyinfool]

The Morgan Carbtune is probably the most popular sync tool on this site. It looks and works like a manometer but it is impossible to suck anything into the engine no matter how far out the sync is.

 

I did buy the kit for the electronic one, once I get it built and try it out, either the electronic or the Carbtune will be for sale, I don't need 2 of them.

[syscrusher]

[quote=Flyinfool;927653

I did buy the kit for the electronic one, once I get it built and try it out, either the electronic or the Carbtune will be for sale, I don't need 2 of them.

 

I seriously doubt you will be selling the electronic one.....

[Blackmax88]

Opinion: The symptoms indicate that the fuel levels are much too high.

How are you measuring the level ( in the tube against what benchmark) and how many mm are you reading ?

What did you do after you removed the idle adjustment needles ?

Have you ever "shotgunned" the carbs ?

Have you run up the engine and turned off the fuel pump to see how the engine responds as the fuel level drops in the carbs ?

 

If the carbs are correctly syncronised,the fuel levels are within spec AND the idle circuits are clear and operating normally then adjustments to the idle screws will have noticeable effect.

2 1/2 turns out is a only starting point for tuning the idle range in these Mikuni downdraft carbs. The final settings could be a turn or more either way.

FWIW

All this assumes that the engine valve clearances are within spec

[bongobobny]

Sounds like the float levels are too high...

[BlueSky]

As I posted I checked the float levels in accordance with the procedure in the manual and they are all set correctly.

[Blackmax88]

Which benchmark did you use to measure the levels against ?

How many mm from the benchmark was the fuel in the tube ?

Was the fuel pump switched on each time you checked the levels ?

 

" " What did you do after you removed the idle adjustment needles ?

Have you ever "shotgunned" the carbs ?

Have you run up the engine and turned off the fuel pump to see how the engine responds as the fuel level drops in the carbs ?" "

[BlueSky]

The procedure states that the fuel level should be 15.5 to 16.5 mm below the center of the diaphragm covers. The engine was running when I checked and I revved it to make sure I knew where the lever was staying.

I know the mixture screw jets are not plugged. I just made sure all the parts were there.

No, i haven't "shotgunned" the carbs.

No, on the last one.

[Blackmax88]

Some comments and opinions which may be of help.

I haven't seen a manual which says to use the center of the covers as a benchmark but it is used. The "correct" benchmarks are : on the carb body behind the diaphragm cover on the LHS in amongst the "Mikuni", "Made in Japan" raised lettering is a small horizontal bar. This is the mark usually used for fuel measurement with the carbs on the bike. Yamaha recommends you use their graded site glass on plastic tube. There is another similar bar marker on the back of the float chamber but you can't see this with carbs intact. If you want to use the center of cover (and I use it) you must first very accurately locate the center. This can be done by string lining the 4 bolts diagonally top and bottom and marking where the 4 strings (cotton threads) cross in the center. Mark this posi with a fine center punch mark. Get a "Post it" sticker and mark on it "0" then 14mm down from the zero line, and 16 mm from zero. Place the sticker with the zero on the pin mark. Zero is your bench mark, fuel level between the 14 and 18 mm marks. Problem with this is that the cover's bolt holes are usually a sloppy it ion the bolts so the cover is never accurately centered and moves each time you loosen the bolts.

All the marks relate to the center of the needle jet, fuel level is +/- 15mm below this.

Check to see if the fuel level is holding with the fuel pump on. Float valves with poor seats are known to unseat with vibration or excess fuel pressure.

If the rich running is prevalent at mid throttle settings, look for worn slide needles and /or worn oval needle jets.

Make sure the air filter is clean.

The fact that the previous owner had the idle adjustments screwed in indicates he may have been trying to correct the rich mixture ...it won't.

You can see if the idle jets are clear but you can't see if the idle circuits connecting PAJ 1 and PAJ 2 are clear. At the very least you should blow out these 2 jets using a can of carb cleaner with a straw with the idle screws ( and O rings and washers) out of the carb body before attempting to set the idle mixture. Better still if you "shotgun" the carbs, however, setting the idle will not fix the obviously rich setting.

If you are absolutely certain that the fuel levels are behaving themselves under pump pressure and are correctly set, the problem may lie with the rubber plugs which seal the bottom of the main jet block. If they are loose (or missing) fuel may be drawn in quantity directly into the throat at all engine speeds..

In the end, you may have to pull the carbs and clean and set them on the bench.

FWIW