Does this sound like a float problem?

[ack1961]

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.

I really do appreciate all your time and effort in trying to help me here.

I went to Action Yamaha in Edison/Metuchen and sat down with Kurt.

BTW, I just got the replacement seat from Sudco - it looks nothing like the original valve seat in my carb. I was kind of expecting this. Below is a picture of the replacement, which is part # N361-03-3.80 (you can see 3.8 stamped on my original valve seat on one of the pictures I posted earlier in this thread)

So, I went out to try to overflow tube test - turned on petcock - no leaks. Start it up, no leaks. I've had the petcock open for the past 25 minutes. Not a drop. I've been jumping up and down on the pegs trying to get this thing to leak...no dice. I think this bike just hates me.

I went to Jersey for 3 days, and had the petcock Off, and there was a puddle on the mat when I came home yesterday.

So, for right now, I cannot get the fuel to leak in order to perform the test (which is a neat test, by the way). If it starts to leak, I'll post the results.

[450wr03]

My 03 did the same thing on me a few times and the problem was the needle had a little gummy build up on it. I sprayed some carb cleaner on the needle and polished it just a little bit with steel wool and made sure it wasnt hanging up anymore put it back together and not a problem since

[William1]

Your picture of the seat is showing it upside down. That 'flange' is where the oring sits, then it is pressed into the carb body. I cannot tell for sure if that is the right or wrong seat. It does not look right but pictures can be deceiving, depending the angle of the shot.

Action is ok, but not the best shop in the state. They cater to the sportbike riders and cruisers. Best Yamaha dealer in NJ now is Speers on Main St. in Passaic.

If you had the petcock off and there was a puddle, that is the drain not sealing.

[ack1961]

Your picture of the seat is showing it upside down. That 'flange' is where the oring sits, then it is pressed into the carb body. I cannot tell for sure if that is the right or wrong seat. It does not look right but pictures can be deceiving, depending the angle of the shot.

Action is ok, but not the best shop in the state. They cater to the sportbike riders and cruisers. Best Yamaha dealer in NJ now is Speers on Main St. in Passaic.

If you had the petcock off and there was a puddle, that is the drain not sealing.

Upside down? Wow, I REALLY don't know what I'm doing.

How can it be upside-down if the Float Needle sits right there in the Hex-head side? The other side (with the smaller of the two openings) has the groove for the o-ring (just under the vent holes) would sit deep inside the cavity.

As for Action: they probably sell more ATV's and Watercraft than the other two combined. Lotsa watercraft leaving that shop. Their Service Dept. had a mixed bag of fun stuff being serviced. That tech stopped what he was doing, sat me down and started searching micro-fiche on his computer. He got up, walked to the Parts Dept. and verified the parts. He could've waived me and my $6 worth of parts questions away. Not saying it's the best - there is no "best", but finding a friendly, helpful (English speaking) person in Edison, NJ is rare.

Like you mentioned previously, if the fuel is dripping out with the Petcock in the Off position, the Drain Screw might be the culprit. I have it as part # 1198-810-2002

[William1]

LOL, I meant I want to se it facing as it would in the carb. The first picture was decieving. Your next series of pictiures confirmed it is the correct part.

Not sure if just the screw will solve the drip unless ihe one you have does not have the taper tip. A lot of people crank them real tight when closing and that buggers up the sealing surface in the float bowl. They should only be snugged.

Glad the dealer tech spent the time with you. That is how it always was at all dealers 'back in the day'.

[ack1961]

Not sure if just the screw will solve the drip unless ihe one you have does not have the taper tip. A lot of people crank them real tight when closing and that buggers up the sealing surface in the float bowl. They should only be snugged.

You may be right there.

With the Petcock Off, the dripping is now constant through the overflow tube.

I went to see how snug the overflow screw was, and it was real tight.

I backed it off and the fuel flow was steady.

I tightened it back up (to just snug) and it just drips (as it was before).

I ordered a new Drain Screw earlier this morning - not sure if that's going to do anything, but for $8, it's worth a shot.

Pulled the carb and set the Float Height to 10.5 mm.

This also gave me a chance to put on a billet Hot Start nut.

I'll leave the carb off until the new drain screw gets here.

Edited July 13, 2011 by ack1961

[ack1961]

OK, what am I missing here?!?

The fuel drips out, regardless of the petcock position.

So, with the petcock Closed, I opened the float bowl drain screw to get all the fuel out of the float bowl. After it has stopped flowing, I tighten the float drain screw back up (snug, not overly tight).

I figure that since the petcock is "Off", and I just drained the carb, that no fuel should leak out right?

I kept a clean/empty cup under the overflow tube.

In the morning, the catch cup is half filled (approx. 6 oz. of fuel in it)...and it continues to drip.

I'm thoroughly confused by this.

[FORMA MOTO]

OK, what am I missing here?!?

The fuel drips out, regardless of the petcock position.

So, with the petcock Closed, I opened the float bowl drain screw to get all the fuel out of the float bowl. After it has stopped flowing, I tighten the float drain screw back up (snug, not overly tight).

I figure that since the petcock is "Off", and I just drained the carb, that no fuel should leak out right?

I kept a clean/empty cup under the overflow tube.

In the morning, the catch cup is half filled (approx. 6 oz. of fuel in it)...and it continues to drip.

I'm thoroughly confused by this.

If gas is escaping the float bowl, then the float needle is not doing it's job.

Have you tried mocking up the carb with the float bowl off, to see if the valve works when gas is applied, and you push up on the float to shut off the flow?

[ack1961]

If gas is escaping the float bowl, then the float needle is not doing it's job.

Have you tried mocking up the carb with the float bowl off, to see if the valve works when gas is applied, and you push up on the float to shut off the flow?

I haven't tried that, but I will. Thanks.

That seems like a good test for when the fuel in On.

What's really got me baffled is the constant drip of fuel out the overflow with the petcock Off.

I just checked - I filled up another 6 oz. cup of fuel last night.

This might seem like the dumbest question of all time, but I have to ask:

Is there any chance that the Fuel Tank Cap (or the vent hose) could be causing this?

[FORMA MOTO]

I haven't tried that, but I will. Thanks.

That seems like a good test for when the fuel in On.

What's really got me baffled is the constant drip of fuel out the overflow with the petcock Off.

I just checked - I filled up another 6 oz. cup of fuel last night.

This might seem like the dumbest question of all time, but I have to ask:

Is there any chance that the Fuel Tank Cap (or the vent hose) could be causing this?

No.

Fuel enters the carb in one place only: via the float vavle and seat.

So, if there is gas coming out the overflow hose, it's because the float valve/seat are not working. The float should rise, put pressure on the needle, which in turn closes the passageway, and stopping all gas from entering the carb. Your float is rising (or not?!?) and closing the passage way, but not completely. So, the bowl fills up past the overflow tube (the brass tube the sits high off the floatbowl) and flows out the overflow hose.

You are focusing on the petcock, which is not the issue.

http://en.wikipedia.org/wiki/File:Carburetor.svg

[ack1961]

No.

Fuel enters the carb in one place only: via the float vavle and seat.

So, if there is gas coming out the overflow hose, it's because the float valve/seat are not working. The float should rise, put pressure on the needle, which in turn closes the passageway, and stopping all gas from entering the carb. Your float is rising (or not?!?) and closing the passage way, but not completely. So, the bowl fills up past the overflow tube (the brass tube the sits high off the floatbowl) and flows out the overflow hose.

You are focusing on the petcock, which is not the issue.

http://en.wikipedia.org/wiki/File:Carburetor.svg

Thanks for that explanation. It all makes sense, but can you explain how gas is getting into the carb with the fuel shut off?

[mjslim]

Thanks for that explanation. It all makes sense, but can you explain how gas is getting into the carb with the fuel shut off?

The only way gas could be getting to the carb with the fuel shut off is if the petcock seal was bad. Easy to test. Disconnect the fuel line from where it goes into the carb and route it to some catch container. See if fuel continues to leak over time with the petcock off.

[FORMA MOTO]

Thanks for that explanation. It all makes sense, but can you explain how gas is getting into the carb with the fuel shut off?

I did not see that you had TWO issues:

If the petcock leaks, replace the o-rings, or the whole petcock.

That would be why your needle valve and seat went bad: old gas contamination.

[ack1961]

I did not see that you had TWO issues:

If the petcock leaks, replace the o-rings, or the whole petcock.

That would be why your needle valve and seat went bad: old gas contamination.

When I disconnect the petcock from the carb's fuel inlet, is drips for about a minute, then stops. I think the petcock is OK- but they're cheap. I'll get a new one.

My biggest issue is that my valve seat is the old pressed-in type, and is considered a "non-replaceable" item. I've been told that i can use a slide hammer to get the old valve seat out. I don't really know how that would be accomplished, and I'm not confident enough to try it without getting some instruction first.

Actually, the real problem is trying to find the correct replacement seat. I have the o-ring and a valve seat, but it's for a later model of the FCR MX39. This is killin' me. I posted pictures of the current valve seat (in its cavity) and the replacement, which doesn't look anything like the original.

[FORMA MOTO]

When I disconnect the petcock from the carb's fuel inlet, is drips for about a minute, then stops. I think the petcock is OK- but they're cheap. I'll get a new one.

My biggest issue is that my valve seat is the old pressed-in type, and is considered a "non-replaceable" item. I've been told that i can use a slide hammer to get the old valve seat out. I don't really know how that would be accomplished, and I'm not confident enough to try it without getting some instruction first.

Actually, the real problem is trying to find the correct replacement seat. I have the o-ring and a valve seat, but it's for a later model of the FCR MX39. This is killin' me. I posted pictures of the current valve seat (in its cavity) and the replacement, which doesn't look anything like the original.

I just looked at your pics again.

Why did you split the carb body??? You are not supposed to do that.

Where did you find a rubber body seal to replace the original?? You can't re-use the old one................

If the body leaks, you are never going to fix it.

You HAVE to check the continuity of the needle valve seat with the needle valve, to know anything meaningful.

[ack1961]

I just looked at your pics again.

Why did you split the carb body??? You are not supposed to do that.

Where did you find a rubber body seal to replace the original?? You can't re-use the old one................

If the body leaks, you are never going to fix it.

You HAVE to check the continuity of the needle valve seat with the needle valve, to know anything meaningful.

I've had this carb apart several times and have replaced all the float bowl components with new. I've set that float height to spec (8mm) and also in the range (10.5mm) of what another helpful person recommended. The problem got better (from a flow to a drip), but it still needed to be fixed properly before I rode it.

Once I was told that my carb was shot because the valve seat o-ring was bad, I split the carb body to see if I could get to (remove) the valve seat from the under-side. Of course, you can't, but I didn't know any better.

For something that's not supposed to be split, they sure made it easy and tempting to split that carb body with those 4 very accessible screws.

For every person telling me that the valve seat (and its o-ring) is not removable or repairable, there is another person telling me to tap in a sheet metal screw or use a slide hammer to get the valve seat out.

My version of the FCR MX39 seems to be different than most. Even the pressed-in valve seat is different than anything I can find on a exploded view or fiche. You can see the differences in the valve seat in my carb and the replacement that was sent from the pictures I've provided.

After each reassembly, I've tested the functionality of the needle by blowing in the fuel inlet and gently pressing on the needle, seating it in the cavity. Without fail, the needle seat and blocks the air passage.

For what its worth, putting a wearable item like an o-ring (consistently soaked in fuel) under a non-removable/replaceable item (my pressed-in valve seat) is the ultimate in poor foresight/engineering. The fact that Keihin seems to have fixed that problem in later models speaks volumes. They should have issued a recall on my model carb.

Regardless, I'm looking for a replacement carb.

I'm guessing that I need one with Hot Start, TPS and Air Cutoff Valve (not really sure how to tell if my carb even has a Air Cutoff Valve).

I'm researching to see if this will fit my '03 WR450:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130545272943#ht_500wt_956

BTW, I really appreciate your time and effort in trying to help me get this sorted out. I just want to ride the bloody thing! I just bought it and have barely been on it. Under it? Yes.

[FORMA MOTO]

I've had this carb apart several times and have replaced all the float bowl components with new. I've set that float height to spec (8mm) and also in the range (10.5mm) of what another helpful person recommended. The problem got better (from a flow to a drip), but it still needed to be fixed properly before I rode it.

Once I was told that my carb was shot because the valve seat o-ring was bad, I split the carb body to see if I could get to (remove) the valve seat from the under-side. Of course, you can't, but I didn't know any better.

For something that's not supposed to be split, they sure made it easy and tempting to split that carb body with those 4 very accessible screws.

For every person telling me that the valve seat (and its o-ring) is not removable or repairable, there is another person telling me to tap in a sheet metal screw or use a slide hammer to get the valve seat out.

My version of the FCR MX39 seems to be different than most. Even the pressed-in valve seat is different than anything I can find on a exploded view or fiche. You can see the differences in the valve seat in my carb and the replacement that was sent from the pictures I've provided.

After each reassembly, I've tested the functionality of the needle by blowing in the fuel inlet and gently pressing on the needle, seating it in the cavity. Without fail, the needle seat and blocks the air passage.

For what its worth, putting a wearable item like an o-ring (consistently soaked in fuel) under a non-removable/replaceable item (my pressed-in valve seat) is the ultimate in poor foresight/engineering. The fact that Keihin seems to have fixed that problem in later models speaks volumes. They should have issued a recall on my model carb.

Regardless, I'm looking for a replacement carb.

I'm guessing that I need one with Hot Start, TPS and Air Cutoff Valve (not really sure how to tell if my carb even has a Air Cutoff Valve).

I'm researching to see if this will fit my '03 WR450:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130545272943#ht_500wt_956

BTW, I really appreciate your time and effort in trying to help me get this sorted out. I just want to ride the bloody thing! I just bought it and have barely been on it. Under it? Yes.

Yeah, it sucks chasing down gremlins.

That carb looks weird. Not like what was on my '03450.

[ack1961]

Yeah, it sucks chasing down gremlins.

That carb looks weird. Not like what was on my '03450.

Yeah, I just heard back from him - no Air Cut-off or Hot Start on it.

Oh well, back to the search.

Thanks,

Steve

[ack1961]

There's a guy I found who has:

"fcr-mx39's that have the removable adapter + acv/ hottstart/ tps/ choke/ $350 + shipping"

It sounds like the correct one, but to be honest, I'm not sure what the "removable adapter" is, or if my carb has an ACV (I think it does, I'm just not sure of where it is or what it does).

[FORMA MOTO]

There's a guy I found who has:

"fcr-mx39's that have the removable adapter + acv/ hottstart/ tps/ choke/ $350 + shipping"

It sounds like the correct one, but to be honest, I'm not sure what the "removable adapter" is, or if my carb has an ACV (I think it does, I'm just not sure of where it is or what it does).

Contact SUDCO regarding details of any FCR carb. They are the importer.