Set the Float Levels on QuickSilver

[V7Goose]

This post describes the proper way to set the carb floats on a 2nd Gen, as well as pointing out the errors in the factory shop manual. If you follow the manual as written, you CANNOT properly set the floats.

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Today I decided to pull the carbs on my 05 RSV and check the float levels. My plugs looked perfect before I touched anything, so that doesn't sound like it was running rich. However, I ran down to Galveston and back yesterday (650 miles) and the chrome tips of my pipes collected a lot more black soot than I like. Even though my gas mileage is still running right where it always has (averaging 36 - 38), I decided to check out the float levels before my next big trip. I first tried the tube method to check the level while they are on the bike, but it just didn't seem to be working right or even close to an accurate way to measure them. So I bit the bullet and tore into it - Seems like a BIG job to pull that danged carb assembly out! The good news is, it really isn't that hard, just seems like it. Se the next post for tips on getting the carbs in and out.

 

I was quite surprised to find that although all four carbs had the floats set very close to each other, they were WAY off the spec. Where the manual calls for .32 - .36", mine were all at either .133 or .285 (depending on how they were measured). That means the float level was set VERY high.

 

And now to discuss the right way to measure the float height. The drawing in the shop manual clearly shows a carb being held upside down with the float bowl gasket surface level and the float height being measured with a caliper held vertical. Seems straight forward, no? But it is very wrong! Done that way, mine measured .133" instead of .34". The instructions even clearly state to "hold the carburetor upside down." But then the next thing is this NOTE:

"The float arm should rest on the needle valve without depressing it." And that comment is the only thing correct about this procedure in the shop manual!

 

Now having the float arm not depress the needle valve is a difficult thing to do with the carburetor upside down - in fact, it is virtually impossible; the weight of the float fully compresses the spring loaded plunger in the needle valve. When you lay the whole carb assembly flat on the bench, the carbs are already inclined quite a bit, but even then the weight of the float is still too much for the needle valve spring:

 

Sooooo, I propped one end of the carburetor assembly on a short 2x4 so that the face of the float bowl was almost vertical. When you slowly raise the end of the assembly high enough you can see the float suddenly pop up from the spring pressure of the needle valve. Here is a picture of the carb assembly propped up and one of measuring the float height in that position:

 

CAUTION: The floats have different shaped sides, and they are different heights too! The wide side of the float measures .04" higher than the other side. This means that you need to be careful to measure the SAME side of the float on all four carbs, and the wide side is the best one to use (note that the picture above is wrong, in that it shows me measuring the thin side of the float!). The most difficult part of the measurement is making sure the tool you use is held truly straight and perpendicular to the carb base, since any leaning at all will significantly change the measurement. On two of the carbs, you will find the choke rod or one of the carb mounting brackets in the way, so turn the caliper sideways a bit to clear the obstruction while still being held straight out from the carb base.

 

I used this position to set all four floats at the mid point of the spec - .34" Bike ran great when I got it all back together, and the sync on the carbs was not changed by the procedure. I only put about 30 miles on it tonight, so I may not be able to report on the effect to my MPG calculation until I get on the road to Ontario next week. But I'll let y'all know how it changes, if at all.

Goose

 

UPDATE:

OK everyone, the results are in, and this relatively straight forward maintenance procedure produced AT LEAST a 10% improvement in my fuel mileage! My carbs were in perfect sync before I adjusted the floats, and I made NO other changes. Although I have not had the time to check my fuel mileage under all conditions yet, I HAVE done about 2,000 miles of high speed, fully loaded, two-up riding. Under conditions that that have always resulted in about 32 MPG (80+ MPH and loaded, all day long), I now get 35-36 MPG. When running at an indicated 84 MPH, I can now get a full 200 miles out of a tank - never could get that far at those speeds before. And inside the chrome tips on my pipes look better now too - more brown than black. I expect it to get even better after I set the mixture screws soon.

Edited February 6, 2016 by Freebird
Added Results

[V7Goose]

Getting to the Carbs:

Start by removing the seat and tank.

 

To get the air plenums off, you will need to first remove the metal straps on top (four screws each), and the two screws holding the crank case vent hose in the middle, then pull the hoses and wire bundles off to the side. After the clamps on top of each carb and the front clamp are loose, each plenum will just pull straight up. When taking off the metal straps, note that the inside front screw on each is longer than the other three, and be CAREFUL when putting all of those screws back at the end of this job - the plastic will strip very easily! Just barely snug the screws, do not try to get them tight.

 

When you pull the crankcase breather connection loose from between the two air plenums, be careful of the little foam rings, most of them are stretched and falling apart - unfortunately they don't seem to be available in the parts breakdown. If your foam rings are torn or just stretched too bad, you can take them off and put a small bead of RTV gasket compound around the part in their place.

 

When you lift off each air plenum, there is a vent hose connected on the rear that will just pop off (watch out for the little wire spring clips - they aren't really necessary, but you don't want to have one pop off and get stuck in a carb or something).

 

Pull the carb assembly:

Start by disconnecting the fuel line behind the right rear carb and open the two clips on top of the carbs to release the fuel line that goes to the tank. Then disconnect the two vent/overflow hoses that connect on top between the carbs and run forward to the front of the air filters. If you remove the vent hoses completely from the bike, you will have to pull either the lower cowlings or the air filters to put the ends back in the little rectangular clips in front of the filters. Best to just take them loose from the carbs and let them pull out the front of the carb frame when you take the carbs out of the bike. Also watch for the little plastic clip that holds them together between the carbs; you will need to take that off before you can pull the houses free. And judging by the number of those clips I find missing on older bikes, it seems a lot of folks forget to put it mack when they put the bike back together!

 

At this point, all you need to do is loosen the hose clamp beneath each carb (but see the caution below) and disconnect the two electric plugs for the wires connected near the left front carb. You will find both of these plugs right up next to the frame under the large main wire bundle. The white two-wire plug is for the carb heaters, and the black triangular three-wire plug is the throttle position sensor. With the hose clamps below all four carbs loose, you can pull straight up on the assembly on each side to "pop" them loose from the intake manifolds (and this usually takes a lot of force!). With the carb assembly loose it slides straight out the left side. I generally wait until this point when the carbs are part way out to disconnect the throttle cables - access is much easier. Just loosen the long nut on each cable to allow it to slip off the bracket - as long as you don't move the small nut, the cables adjustment will not change.

 

CAUTION! The screws on the hose clamps on the bottom of each carb are VERY soft metal. In addition, those clamps each have a metal collar to prevent you from over tightening them on the rubber boot. This means that the screws CAN be overtightened enough to freeze in place from the metal-to-metal contact. On most of the bikes I have worked on, at least one of those screws has been frozen so hard that the head stripped out, requiring me to drill the head off to remove the clamp. If you have this same problem, stuff a rag under the clamp before you drill it off so you don't loose that little collar. The screw can then be replaced with any standard 4mm screw from the hardware store.

 

Another word of caution if your bike has the chrome carb covers - when you take those covers off, you then only have one screw holding on the plastic diaphragm covers. Be very careful to NOT pull up on those covers when you are trying to pull the carbs free from the intake boots, as you can damage them or dislodge the little o-ring.

 

Putting the carbs back in:

After making sure the hose clamps are still properly positioned on the top of the intake manifolds, slide the carbs in from the left side, but leave them just far enough out to make it easy to attach the throttle cables. Also make sure you start the two vent hoses through the hole in the front carb frame before you push the carbs all the way in. Then after making sure all the carbs are centered on the manifolds, you need to push down on them pretty hard to pop them back in place. Try to put the base of your hand on top of the carb throats, not on the plastic diaphragm covers. Re-route all the fuel lines and vent hoses appropriately, and don't forget to re-connect the two electrical plugs. Putting a drop or two of WD40 on each of the rubber intake boots will make it much easier to push the carbs back into place.

 

Putting on the air plenums:

Those air plenums that fit on top of the carbs WILL slide on and NOT try to push back up. I stress this here because a lot more experience has shown me that EVERY SINGLE TIME those air boxes want to spring back up when put back on top of the carbs, the rubber is caught someplace and buckled under the hose clamp.

 

Start by making sure all three hose clamps are very loose (the two on the air plenum throats to the carbs, and the one on the rubber Y-connection in front of the air plenums). If you do not have that rubber throat caught on the neck of a carb, the box will fit nicely in place with ZERO movement, even as the hose clamps are tightened. Typically, the problem will be on the front carb; you need to push the plenum much further forward than you think to clear the front side of that carb and get it to slip into place without problems. If the rubber is not buckled in there, the plenum will fit fully down on the carbs and not spring back up at all.

 

Unlike the lower hose clamps, those on top of the carbs do not have a metal collar to prevent them from being over tightened, so just make sure they are properly set in the grooves on the plenum and snug them up pretty good instead of trying to play Magilla.

Edited November 19, 2011 by V7Goose