More Stories on the RSV Float Levels

[RandyR]

Goose,

 

There is a possible reason for the failure of the fuel level tube not to be working as expected. I suspect that when you attached the tube to the drain, and fuel started to drain, it stopped when a partial vacuum was created in the float bowl. Air has to be able to enter the float bowl freely for the tube level to be accurate.

 

 

 

 

OK, since Taz insisted on broaching this subject, I guess I'll have to address it, at the huge risk of loosing all credibility here.

 

First, let me stress that you read the details of my tech article on this job - I tried to be very specific on the one and ONLY correct way for ME to check and set the float levels on this bike. That requires the carbs to be out of the bike and opened up.

 

OK, here is where my credibility is probably going to go down in flames . . . The shop manual clearly tells you how to check the fuel level in the float bowls while they are on the bike! Yamaha even has a special tool specifically for this. But it just doesn't work!!!!! (The method, that is, not the tool - I ain't got that tool). I cannot explain why I couldn't get it to work, and all logic, fluid dynamics, physics, geology, other sciences and mystic visions say it MUST work. But it don't. (poor english intended) You simply connect a tube to the bowl drain, open the drain screw, and measure the gas level in the tube held next to the diaphragm cover. What could be simpler, right? Liquid MUST seek it's own level in an open tube, right? Well, not on this bike. See, I told you I was gonna loose all credibility here! Now everyone KNOWS I'm a crackpot!!

 

I farted around with that tube for an hour! Never once got a reliable fuel level. And yes, I'm pretty sure I made sure the drain screw was way open! At first, the gas only ran into the tube to the lowest level; it would absolutely not come back up to anywhere near the bottom of the float bowl, let alone diaphragm level, even with the key on so the fuel pump ran enough to ensure the bowl was full. So then I dropped the open end of the tube to let the gas completely fill it, but when I raised the open end again, the gas would not drain fully back down to the required level. I guess this makes sense, since the float valve had to be closed, but my point is I tried all sorts of different things to try and get a reliable and repeatable external fuel level. And I failed miserably. The only thing I didn't try was to start the bike and let it run, where maybe all the dynamics of the fuel pump running, vibration, and normal fuel flow through the carb would have produced the correct results? But by that time I was just pissed off at it. And now I don't care. Ya see, EVERY one of these bikes that I have checked has had the floats way off, and there is no way to adjust them without pulling the carbs anyway! So that is where I start.

 

Go ahead, laugh at me and point - see if I care! (now where did I put that damn beer?)

Goose

[V7Goose]

Goose,

 

There is a possible reason for the failure of the fuel level tube not to be working as expected. I suspect that when you attached the tube to the drain, and fuel started to drain, it stopped when a partial vacuum was created in the float bowl. Air has to be able to enter the float bowl freely for the tube level to be accurate.

Nice theory, but I can't see how it could be - the float bowls are always open to the atmosphere through the jets. But thanks for trying. I hate to just shoot down ideas when I can't explain it, and I would really like to learn what was wrong.

Goose

[RedRider]

Ya know Joe, that is a heck of an idea! I have briefly thought about it before, but never seriously. I just focused on trying to do a good tech article for things like this so everyone could access the info for free. But now you got me thinking . . . a very dangerous thing . . .

 

I've got the equipment to do it, just never considered going to the effort. But I can see the possibility of doing one for the carb floats, carb sync, exhaust gas analyzer, clutch, gauges, changing tires, rear drive pins, etc. Heck, I'm even getting ready to do my swing arm bearings, steering head bearings and valves, so maybe this is a good time to start? I'll have to see if my wife wants to try being a camera man!

Goose

 

Goose,

 

I would buy (for a reasonable fee that would at least cover shipping) a video of setting the carb floats. Taking the carbs out and putting them back is the part that concerns me. I will, however, take the plung and do it soon - with or without the video.

 

RR

[tazmocycle]

the problem with lowering the tube and leting it fill and then raising it back up, is that the amount of gas in the carb and tube together put it way above the true normal level and it starts coming out of the jets and into the throttle body and on to the floor or table. the jig we set up worked pretty good, but like you said all of them were set toooo high. o'course we only worked on 1 set of carbs. if i get some free time, i have a set of carbs off my wrecked bike that i'm thinking about setting them up and playing with them. i won't be in a hurry to get them fixed to put back on a bike since they're a spare set. you are doing pretty good at what you're doing, the yammie people didn't think this thing thru and they should give a dry float settting like all other carb builders do so they can be set before installing them!! i don't think you're dumb, anybody that dives into these sets of carbs to work on them has to have a good bit of know-how to do it, don.

[ibents]

Ya know Joe, that is a heck of an idea! I have briefly thought about it before, but never seriously. I just focused on trying to do a good tech article for things like this so everyone could access the info for free. But now you got me thinking . . . a very dangerous thing . . .

 

I've got the equipment to do it, just never considered going to the effort. But I can see the possibility of doing one for the carb floats, carb sync, exhaust gas analyzer, clutch, gauges, changing tires, rear drive pins, etc. Heck, I'm even getting ready to do my swing arm bearings, steering head bearings and valves, so maybe this is a good time to start? I'll have to see if my wife wants to try being a camera man!

Goose

 

You know goose this is a brilliant idea, a video of the removal, setting and installation of the carbs would certainly help alot of us, Its to bad this wasn't thought of at MD when you were helping the lucky guys getting theirs done. If Gunkylump gets down there I'll have to make sure he takes a video camera .

 

Ian

[1sttenor]

Well, I wish you were closer to Missouri. I'd love to have you adjust mine!

[V7Goose]

the problem with lowering the tube and leting it fill and then raising it back up, is that the amount of gas in the carb and tube together put it way above the true normal level and it starts coming out of the jets and into the throttle body and on to the floor or table. the jig we set up worked pretty good, but like you said all of them were set toooo high. o'course we only worked on 1 set of carbs. if i get some free time, i have a set of carbs off my wrecked bike that i'm thinking about setting them up and playing with them. i won't be in a hurry to get them fixed to put back on a bike since they're a spare set. you are doing pretty good at what you're doing, the yammie people didn't think this thing thru and they should give a dry float settting like all other carb builders do so they can be set before installing them!! i don't think you're dumb, anybody that dives into these sets of carbs to work on them has to have a good bit of know-how to do it, don.

You are correct about the reason for that test to fail - without the float needle being open (and no back pressure on the inlet line), there was no way the fuel in the external tube could have ever fallen completely to the correct level. I was simply trying to force the gas into the line to verify it was really there in the bowl (obviously it was), and to see if I could then get a repeatable level in the hose that would be at the lowest jet point. I figured if I could achieve that, I would be comfortable that the fuel was then flowing back and forth in the tube, having overcome the normal forces that restrict fluid from moving in a small tube or whatever original problem I had. Then I could drain it and start over. But since I could not even get a repeatable level that way, there was no point in starting over. I didn't want to take the time to go over all those mundane details in the already long post. In fact, I was simply making a weak attempt to be a little funny while also letting other readers know WHY I did not tell them to check the level with the external tube before tearing into the carbs.

 

If you would look at either my tech article or the shop manual, you would see that Yamaha DOES provide the correct measurements for setting the floats on the bench (the "dry setting" you keep referencing), and that is exactly where I set them. The biggest significance in my tech article is to explain how to do this correctly, as the Yamaha shop manual has a number of errors. It is, in fact, flat wrong in part of the specific instructions on how to measure the floats. Thanx for your comments,

Goose

Edited June 11, 2009 by V7Goose

[stevel]

OK I am going to do mine,Wish I had read about this before I had removed my carbs the first time. With that said is their a thread on this somewhere with procedure and proper float levels. I have a 98 RSTD with poor mialage.

[tim44]

Well as I had a day off I decided to take Mr Goose advice and tear into it. This was the first time I took the carbs off this bike since I bought it last fall. The operation on my patient was easier than I anticipated. The tech forum on this site is awesome. Many thanks to all who have put so much effort into sharing their knowledge with the rest of us. The float levels were off by .1" to .15". So I will have to see what happens to my gas mileage now that I have them set correctly, via the Goose Float Mod. Anyway, I also found another problem. The number three carb diaphram was not completely in place. I believe that was from the factory but not sure as the bike had 15,000 miles on it when I got it. Many thanks again to those who share their knowledge on this forum.

 

Tim

[gibvel]

Well as I had a day off I decided to take Mr Goose advice and tear into it. This was the first time I took the carbs off this bike since I bought it last fall. The operation on my patient was easier than I anticipated. The tech forum on this site is awesome. Many thanks to all who have put so much effort into sharing their knowledge with the rest of us. The float levels were off by .1" to .15". So I will have to see what happens to my gas mileage now that I have them set correctly, via the Goose Float Mod. Anyway, I also found another problem. The number three carb diaphram was not completely in place. I believe that was from the factory but not sure as the bike had 15,000 miles on it when I got it. Many thanks again to those who share their knowledge on this forum.

Tim

 

Tim,

 

Let us know what your mileage before and after were, for sure. May have to come to your place for a carb maintenance day sometime soon.

[RandyR]

OK I am going to do mine,Wish I had read about this before I had removed my carbs the first time. With that said is their a thread on this somewhere with procedure and proper float levels. I have a 98 RSTD with poor mialage.

 

 

VentureRider.Org > Technical Library - Read Only > Second Gen and Royal Star Technical Library > Engine and Drivetrain

[RandyR]

Here's a picture of the Yamaha fuel level tool. 90890-01312

[sleadhed]

Thanks for that information, most appreciated !!

George

We should get together and set out float levels. I have a home made sync. set up that works great.

Ken C.

[schemer]

Hi Guys,

Old post I see but I am working on a set of carb's for a 1999 Royal Star 1300. I have already build them but I was curious too about a dry setting for the floats. Does anybody have that info? Also, being I already build and assembled the 4 carb's I should be able to check and set the floats with the wet method on the bench ok as long as I get the carb's level?

Thanks,

schemer

[ccrider1]

Hi thank for all info on this site very good site to learn.

[ccrider1]

OK carbs off clean up and set float what a good idle set and do thing a jet change to 115 mains and 22.5 idle. would work well thank for help.

[videoarizona]

Goose... Did you ever do the video on carb floats? Super film/video producer wants to know?

Shame it's hot out, I'm one day drive from your area!

David

[V7Goose]

Nope - never did make any videos - just always had better things to do with my time.

 

And what do you mean by "Shame it's hot out..."? What better time to ride than that????

goose

[videoarizona]

 

[/color]As I get older, the heat bothers me more. I have troubles when it's over 90 and I'm wearing mesh, gloves and helmet.

Sucks sometimes.....but that's OK, I can ride most of the year...

david

[V7Goose]

 

[/color]As I get older, the heat bothers me more. I have troubles when it's over 90 and I'm wearing mesh, gloves and helmet.

Sucks sometimes.....but that's OK, I can ride most of the year...

david

I can understand, but still not completely buy that excuse. If you head north to Globe and then come across US60, temps should drop pretty quickly this time of year as you begin climbing into the White Mountains. Then you will keep good altitude all the way here. Even if it wasn't a heat issue, that is the only route I would take - that I10 corridor is nothing but butt ugly!

Goose

[videoarizona]

 

Yep....actually done part of that. But it was hot getting to Globe...even leaving early am. [/color]The Devil's Hiway (old rt 666) is another choice up to the White Mountains then across NM. May do that anyway. Want to see the Radio telescope array west of Socorro (sp?)

 

The issue I have is timing the ride so I leave the heat country in early am, finding gas at "O dark 30" on some of those roads and .....my bod can't ride all day like it could when I rode from NH to AZ on a Yammie 250cc! So judicious planning is required! Been riding AZ for 40 years....still amazed how sparse coffee, donuts and gas can be in the boonies.

 

Thanks for the encouragement!

david

[smlogan]

As an addition to the above. I installed KN pod filters on mine with 147.5 mains and 17.5 pilots to get the best AFR and performance. I could pass everything but the pumps, did it ever go compared to stock. I had used Ivan's needles with my own jetting but I had a lean in the midrange I could not get rid of. I bought the factorypro needle set designed for individual filters and adjusted the floats to Yami specs. They were around 6mm on average before adjustment with specs calling for 8-9. My 09 only had 4000 miles on it so I figured they would be good from the factory but as Vgoose said don't trust it. No more midrange lean and the mileage improved but I had lost a little performance. Talked to the tech at factory pro and he insisted I drop the fuel level to 11mm almost 3 mm more than yami specs. I was afraid the bowl would be starving under load but I gave it a shot. Wow no starving fuel economy went up and my performance was amazing again. Yesterdays run at average 65-70mph yielded 43mpg and I wasn't gentle on the twist. My buddies riding the 1600's beside me cant come even close to keeping up to my oversized sofa as they call it. All that to say that better economy may be realized at greater than factory float level specs.