Carb too rich Maybe?

[BlueSky]

My newly acquired 89 VR starts instantly when cold with no choke. Seems to me that the carbs would have to be set way too rich for this to happen. Is this normal or should I adjust the pilot screws? Thanks

[Stache]

My newly acquired 89 VR starts instantly when cold with no choke. Seems to me that the carbs would have to be set way too rich for this to happen. Is this normal or should I adjust the pilot screws? Thanks

 

Are you sure the choke isn't stuck on?

[Prairiehammer]

My newly acquired 89 VR starts instantly when cold with no choke. Seems to me that the carbs would have to be set way too rich for this to happen. Is this normal or should I adjust the pilot screws? Thanks

 

None of the three Ventures I've owned would start without some "choke" when the engine is dead cold. The "choke" (actually an enrichener) can be maladjusted, allowing fuel to flow through the enrichening circuit, even when not intended for a cold start.

 

Have you checked the spark plugs for a rich burn?

 

There will be no harm in adjusting the pilot screws, but make sure that the enricheners are fully closed/off before messing with the pilot screws. When you do check or adjust the pilot screws, keep track and record how many turns it takes to lightly seat the needle on the end of the pilot screw.

[saddlebum]

My newly acquired 89 VR starts instantly when cold with no choke. Seems to me that the carbs would have to be set way too rich for this to happen. Is this normal or should I adjust the pilot screws? Thanks

My 89 has always been the same way. trouble is it runs so good and smooth, with lots of get up and go. When I pull the plugs they are as clean as the day I put them in and so other than doing a carb balance I just preferred to leave well enough alone. The one down side is when on a group ride I seem to use about a $1.00 US more fuel than everybody else per tank fill.

[Venturous Randy]

When the weather is warm, my bike will start and run without using the choke, but the throttle is not as responsive as when I pull the choke on a little, until it has warmed up. To me, mine works as it should and I get good mileage.

RandyA

[BlueSky]

I did some looking at my suspected rich condition by checking the choke. all 4 appear to be completely open judging by the linkage. I previously confirmed that the pilot screws were one turn off the seat.

I then removed the air filter and looked down into the carbs with the engine running. All 4 sliders appear to be working properly. With the air filter off, I got a slight backfire on one carb when I closed the throttle quickly. I assume this is normal with the filter off. The engine didn't appear to be putting out any unburned gasoline running it this way. The air filter was an Emgo and was a little dirty. Could the filter be restricting air flow enough to cause a rich condition? I don't think this is the problem because it responds to the throttle on the road really well. Makes me smile!

The search continues.

[Prairiehammer]

I did some looking at my suspected rich condition by checking the choke. all 4 appear to be completely open judging by the linkage.

Note that there are no "chokes" as in a carb throat butterfly choke. The enricheners on the Venture carbs are just that, enricheners. Instead of restricting air flow through the venturi, the enricheners actually add fuel to the carb throat. When you say: "all 4 appear to be completely open" do you mean that the enrichener plungers are pushed in fully (closed) or that the enrichener plungers are pulled out fully (open)?

I previously confirmed that the pilot screws were one turn off the seat.

 

One turn out on the pilot screws should be quite lean. Normally, the pilot screws are 2½ turns out or so. The further the pilot screw is turned out, the richer.

 

Check your float bowl fuel level. It may be too high, creating a rich condition.

 

Also, the coasting enrichment diaphragms may be defective.

[frankd]

As Prairiehammer suggested, check your float levels, it sounds like they are way high. How's your gas mileage? My 89 used to start great without the choke until I found that my floats were all high. I set them to the proper level, and now if it's above 70F, it'll start without the choke, but it runs lean for a couple of minutes until the motor starts to warm up. This would go along with your pilot adjustments being set so lean. Another indication of this is having good throttle response when it's only been running a couple of minutes. When you pull out on a main road on a cool morning with the choke off and the engine cold, mine bogs a little when you hit the throttle. It had great cold throttle response before I adjusted the floats. High float levels richen up all the carb. circuits.

 

Frank D.

[BlueSky]

Note that there are no "chokes" as in a carb throat butterfly choke. The enricheners on the Venture carbs are just that, enricheners. Instead of restricting air flow through the venturi, the enricheners actually add fuel to the carb throat. When you say: "all 4 appear to be completely open" do you mean that the enrichener plungers are pushed in fully (closed) or that the enrichener plungers are pulled out fully (open)?

 

 

One turn out on the pilot screws should be quite lean. Normally, the pilot screws are 2½ turns out or so. The further the pilot screw is turned out, the richer.

 

Check your float bowl fuel level. It may be too high, creating a rich condition.

 

Also, the coasting enrichment diaphragms may be defective.

 

I checked the choke linkage and all of the enrichment plungers were all the way in. I just assumed there were butterfly valves somewhere too. Wrong!

 

I've got some education in front of me. I rebuilt my Kawasaki carbs but it sounds like they were simple compared to these.

 

Thanks for the help! I really appreciate it. How far do I have to tear down the bike to set the float levels? Also how do I check the coasting enrichment diaphragms? Thanks Again!

[jasonm.]

here's the easiest ACCURATE way to check. 1st bike on center stand.(2nd) remove air box.Note: the air box has 2 hoses connected to it, left front and center rear. (3rd) find a 4 inch level. Shim the center stand till the carb(s) are perfectly level at multiple angles. the carbs are not all level together and will require you check ONE at a time and move shims. I use junk thin steel snd aluminum. (4) Then note the raised line cast into the carbs below the diaphragm area. This simblizes the center of the slide. Connect CLEAR 1/8 hose to the drain(s) one at a time to test. The level is to be 16mm BELOW the cast line. +/- .5mm. As you can see this is a critical measurement. You may wish to scribe a line on the carb at 16mm below this cast line. Start the bike open the drain screw and hold the hose up near the cast line. Physical law will not allow the fuel to read higher in the hose than what is in the carb. Make sure no air bubbles. Then move to next carb and confirm it's level. Note: you may need to by a vacuum adapeter 1/8 to 1/8 to connect the hose.

Edited July 14, 2014 by jasonm.

[H2O]

Kevin, I was reading this thread because of the lean/rich issue I may be having. You and Cowpuc directed me to the float sticking after a recent problem I posted about fuel coming out of my vacuum advance.

Rode to Sikeston and went to Lamberts Saturday.

Somewhere around Garden of the Gods one of my buddies noticed smoke coming out of the right exhaust tip whenever I took off from a stop, or started the bike.

I noticed the idle didn't sound too sharp anymore also. We stopped around 150 miles and I pulled the vaccum advance hose loose and saw no fuel. Thankfully the stuck float is working now.

We made it through the 350 mile day. Apparently The bike seemed to have plenty of power, sounded great on the road at speed, but idled like it may be fouling another plug. They didn't notice it doing it on the return trip, but they said they weren't watching anymore either.

They did say it looked like oil smoke, so I'm wondering if I have a two-fold issue. The bike sat all last summer, barely put 25 miles on her, and of course, I recently had the Yamaha carb kits installed by a local shop.

Started it right up again this morning, without choking it. Sounds like it's okay again. Revved it a little and didn't see any smoke.

Pulled the choke and it brought the idle up. Turned the choke off and found all the choke pins/rods going back in visually.

After reading this thread I'm beginning to wonder if I should check the carbs some more since I don't need to choke start it.

I always park the XVZ inside so I'm wondering if I need to set it outside overnight to see how it does.

I'm going to pull the plugs tonight and see what they look like too.

This is a good thread with some great info.

Any advice?