Does this sound like a float problem?

[ack1961]

All,

I picked up an '03 WR450 last weekend. As soon you you turn the petcock On, fuel pours out of one of the overflow hoses.

I took the carb apart last weekend to clean out the jets and float bowl.

Nothing looked irregular, but I was looking for a reason why the float might get stuck. Thoroughly cleaned everything and inspected the float, needle, pin, etc. I didn't see any holes in the float, but I didn't do a "float test" with it.

Got it all back together, turned on the fuel, no leaks...rode it around the back yard for a few minutes. Still, no leak. I made it a point to turn on the gas everyday and at least run it for a few minutes each day and check for leaks. All good.

Took it with me to ride this weekend. Did a warmup lap on a track, and came back to camp...leaking fuel just like the previous week. Tapped on the float, which changed nothing.

I was open to suggestions, and someone mentioned the float needle "seat", and asked if there s a little rubber seat where the needle perches.

When I took the float off last week, I noticed the retaining clip, the float, the pin, and the needle. I didn't notice any rubber piece, nor can I locate one in the exploded view of the FCR MX39.

I'd like to fix this myself (or at least learn how to fix it) instead of taking it to a shop - I'm certainly no mechanic.

From an OEM WR450 Parts House: I figured, I would need the following parts to replace the entire float assembly:

YAMAHA

FLOAT for 2003 YAMAHA WR450FR

4SR-14985-00-00

$20.09

YAMAHA

PIN,FLOAT ARM for 2003 YAMAHA WR450FR

663-14548-00-00

$4.14

YAMAHA

NEEDLE VALVE for 2003 YAMAHA WR450FR

4MX-14392-00-00

$14.30

YAMAHA

CLIP for 2003 YAMAHA WR450FR

633-14159-00-00

$2.70

Any constructive suggestions would be welcomed.

Thanks,

Steve

[strtdsmallproject]

I had the same problem recently. Float needle. I think the spring on the needle was weak. Mine would do the same thing

[William1]

Most common point of failure is the oring on the float needle seat. These dry out and crak, causeing a seemingly too high or failed float. Easy to bench test. Hold the float needle into the float needle seat, blow in the fuel inlet. If you hear/see/feel a leak, it is the oring. Yamaha Part Number 8F2-14147-00 (float needle seat oring)

To pull the seat you have to very carefully use a small slide hammer if it does not have a retaining screw.

While you have the float needle out, inspect it for gouges or a very deep depression where it seats. If so, replace the seat and needle.

[ack1961]

Thanks, guys.

I ordered the parts I listed as well as the o-ring for the float needle seat (thanks for the part #, William).

I can't hurt to freshen things up a bit in the float bowl. The bike sat basically unused for a couple of years. $40 worth of parts to get it in good shape is nothing.

[ack1961]

To pull the seat you have to very carefully use a small slide hammer if it does not have a retaining screw.

I don't like the sound of that!

[William1]

It is scary unless you have done it before. Once you have done a few, you know the feel and it is very easy. If you are nervous, take it to a competent dealer or machine shop.

[ack1961]

I apologize for the dumb question, but we're talking about the un-numbered o-ring just above the float needle #27, correct?

It looks like it would come off when the un-numbered part below it was loosened/removed.

I'm guessing that's some sort of screen just above the o-ring...

Why these parts are un-numbered is beyond me.

Thanks,

Steve

[William1]

Yup, and above that is a tiny screen/strainer.

Un-numbered because in that fiche, they are not available as spares.

They also do not show the AP check valve asy among other parts.

Notice the fuel screw, buying it is the only way to get the spring, washer or oring.

But you can buy that critical band to hold the vent tubes together (#54)?

[ack1961]

Yup, and above that is a tiny screen/strainer.

Un-numbered because in that fiche, they are not available as spares.

They also do not show the AP check valve asy among other parts.

Notice the fuel screw, buying it is the only way to get the spring, washer or oring.

But you can buy that critical band to hold the vent tubes together (#54)?

Thanks, William.

Sometimes there just no common sense to some of these things.

For instance, I bought the Float parts from Parts Unlimited/Interstate Cycle.

Their FCR MX39 fiche did not list (or even show) the o-ring part # you provided, but I was able to call them and add it to the order.

I swear, if it wasn't for the kindness of folks on these boards, I'd never get anything fixed...

[ack1961]

OK, got the carb off and apart (much, much easier the 2nd time around).

Got all the float components off.

I put the float needle back back in and blew into the fuel inlet. Air was escpaing.

If I very gently press down on the needle, no air gets through.

When I looked inside the brass fitting where the float needle sits, i could see some broken pieces of rubber. I flushed as much as I could out and re-tested. Same deal.

I just wanted to make sure (before I bring the float bowl to a shop) that the only way for me to get this fitting out is to use a small slide hammer, which I neither have, nor am I comfortable doing.

The o-ring that I am replacing (I'm suspecting the pieces of rubber that I flushed out is the old o-ring?) is under the needle fitting (on top in the pics):

Thanks,

Steve

[William1]

Yes, you are correct. When testing , realize the float needle seat has hole around the perimeter and you can only test by blowing in the fuel inlet barb and gently holding the float needle in.

[ack1961]

After 2 days of trying (I even brought it to a Chopper Shop for them to have a look), I am still unable to get this seat out. I've gotten out lots of little pieces of rubber from below the seat (where the o-ring fits), but I've only been able to move the brass seat up about 1mm. I've soaked it in gas and tried gently prying up the outside of the brass seat using tiny screwdrivers. I've tried WD-40 and compressed air, but it's pressed in way too well. I'm starting to mar the outer walls, so I'm stopping the pry method.

At this point, I'm resigned to screwing a self-tapping screwing into the fitting and pulling it out that way. Of course, this ruins the seat, but I it's a part I think I can order. Only problem is that I cannot find the EXACT part number for the brass pin seat. I've looked on some fiche, (usually part #36), but the list of available FCR MX 39 models (Air Cut Valve, Hot Start, TPS, etc.) throws me for a loop. I know it has TPS and Hot Start, Accel. Pump, etc.

I think I need part # "Valve Seat" N361-04xx1 (although I'm guessing that the "xx" matches a specific model of FCR MX 39)

I'll also ship it somewhere if someone knows a shop/person that will tackle this problem.

Steve

[William1]

... which is why I said a small slide hammer. A chopper shop is clueless, most of those places just bolt on Chrome and loud pipes.

I made no mention of prying at it. The rubber no doubt was the needle seat.

PM Eddie Sisernos and ask him to help you.

[ack1961]

... which is why I said a small slide hammer. A chopper shop is clueless, most of those places just bolt on Chrome and loud pipes.

I made no mention of prying at it. The rubber no doubt was the needle seat.

PM Eddie Sisernos and ask him to help you.

Thanks, William - I've been searching for small slide hammers and couldn't find anything that could possibly fit into that small orifice. There was one that may have fit, but for $359 for a tool I'll use once is no way to start a relationship with a new bike.

The soak & pry method was a suggestion of the chopper shop and something I read about while researching this problem.

I'll PM Eddie - thanks for the tip - and all the help.

Steve

[William1]

Small slide hammers cost about $30. They look like a screw driver, with a small weight on the shaft and a gripper on the end to hold a screw. ometimes locksmiths use them.

Here is one I found quickly and not searching for the best price:

http://www.denlorstools.com/home/dt1/page_30783_177/otc_898a_puller_slide_hammer_dent_pulling.html

Soak and pry was so wrong. Bad, bad advice. The seat is not stuck, it is pressed in. Almost noithing ever needs to be 'pried'. Never listen to those clowns again.

[Wayward Son]

small slide hammer. prying is bad.

[ack1961]

I was having a bit of difficulty finding a valve seat (the part is un-numbered in many exploded views), I decided I was going to take the FCR MX39 apart again and replace the float components.

I also have access to a small slide hammer, but I'm not going to remove the seat until I try a few more things. Here's why:

I found my part online, so I ordered another o-ring and the brass valve seat. After I ordered, I called back to ensure that the part I ordered was the pressed-in type, as there are several types available (screw-in, press-in w/ retaining screw) - mine is the pressed-in type.

While speaking to the tech, he said something interesting/scary about my carb. The pressed-in type seats (without the retaining screw) are NOT replaceable items. I basically said that it would be ridiculous to put a wearable part (like the o-ring) under a non-removable component. He agreed, but said that the carb must be scrapped, as my model carb will not properly accept another brass pressed-in valve seat.

Here's what I've done.

I tore down the carb again and replaced:

Float

Float Pin

Float Needle

Float Needle Clip

I tested the valve seat o-ring by blowing in the fuel inlet. When I slightly depress the float needle, the valve seals just fine.

I set the float height to 8mm (as per the Owner's Manual).

Buttoned everything back up and it still leaks. Even with the Petcock "Off", it still drips fuel.

Before I replace the valve seat, which should be here today, I'm going to adjust the float height again. Anyone have any recommendations?

Like I stated earlier, the manual says to set it to 8mm. I've been reading quite a few threads about how my symptoms are not that uncommon and that sometimes re-setting the float height does the trick, although I've never read an actual float height number that worked.

Thanks.

[William1]

If the float needle seat is leaking, resetting the float will not do anything. Your test seems to tell us the oring is not leaking. 8mm is a bit on the tight side, I prefer to go to 10 or 12.

What ever tech you were talking to does not have all the facts. If the parts were not replaceable, you would not be able to buy them, Yamaha would not show them on the fiche. The little oring I mentioned comes when you buy a new seat though if all you need is a $2 oring, why buy a $40 seat?

There are other parts of the carb that you should never take apart and those are not shown on any diagram.

[ack1961]

If the float needle seat is leaking, resetting the float will not do anything. Your test seems to tell us the oring is not leaking. 8mm is a bit on the tight side, I prefer to go to 10 or 12.

What ever tech you were talking to does not have all the facts. If the parts were not replaceable, you would not be able to buy them, Yamaha would not show them on the fiche. The little oring I mentioned comes when you buy a new seat though if all you need is a $2 oring, why buy a $40 seat?

There are other parts of the carb that you should never take apart and those are not shown on any diagram.

I also went to a Yamaha Service Dept. while I was in NJ this past weekend. I got to sit down with their Master Tech for almost 15 minutes. He confirmed that the part for my year/model carb is "considered" non-replaceable, but that doesn't mean that it can't be removed by force in order to replace the o-ring.

Back to the leak - and this is where I get all confused. Let's forget about the o-ring for a second and say that my tests prove that the o-ring is seated/working properly.

What else could be the culprit other than float height? Is there anything in the Drain Screw system that could be faulty? Haven't I eliminated (replaced) all of the other possible failure points in the float section of the carb?

I'm certainly not trying to be difficult. I'm trying to systematically isolate the cause of the problem before I do any irreparable damage to a very, very expensive carb. Like I stated in my first post, I'm not a mechanic - so I'm a bit more cautious.

[William1]

What dealer in NJ?

Ok, we will assume the float needle seat and oring are fine. the float is not set too high (the lower the number, the higher the float).

The next thig is the carb drain/overflow which is the hose on the bottom of the bowl.. This hose does double duty, serving as the drain point for the float bowl and a point for overflow ( remenber the brass tube in the float bowl?) If fuel is coming from that, pull the hose up into a 'U' shape along side the carb. Turn the petcock on. If fuel rises in it and stops at about the gasket line on the float bowl, the drain screw is not sealing. If it rises further than that, it is still a float needle seat issue.