Mechanic question

[qdude]

I have posted about this problem but I'd like your opinion. I have a gas leak. It appears to originate on the right rear carb area. The gas runs down the rear cylinder wall onto the crankcase breather. It leaks less than a teaspoon. A full tank of gas makes the leak worse and the leak disappears when the gas tank is at about 20%.

Recently I changed the plugs, all were very good except for the right front cylinder which was gas fouled. Don't know if that's related to the leak. I took it in earlier to a mechanic for this issue and got it back with new jets, one was definitely corroded green, so it wasn't a complete waste.

 

I took it to the same mechanic who says it is the needle valve/pin stuck.

I looked around and found one reference to the needle valve sensitivity to alcohol and having the valve switched to stainless. Do you think he's right? I don't have much confidence in this guy because he didn't fix it the first time. The nearest certified Yamaha mechanic is 70 miles away.

 

I should just bite the bullet and take it apart my self, but having never done it before I am not 100% confident.

[Yammer Dan]

Sea-Foam

Run the tank down to less than 1/2 tank and give it full can of sea-Foam. Run it as low as you can and leave it sit overnight at least. Couple days is better before you fill it back up.

[Cougar]

And what year and model is this bike?

It might help so other might be able to help you better.

[GeorgeS]

Sounds like the Float valve in that carb might be sticking open.

 

There is an overflow on each carb, which , Might be the source of the gas.

The SEA-FOAM treatment might fix it.

 

Also, there are several sections of fuel line on top of the Carb Bank, One of those hoses might be leaking. But Mech, should have found that.

[skydoc_17]

I think we are talking about a 2004 RSV. As for the rest of it, I have no clue what we are talking about. Is you mechanic talking about the Idle Mixture Adjustment Screw or the Main Jet that is in the Diaphragm Slider? Could it be that the Bowl gasket is leaking, which indicates to me that when your mechanic installed the "new jets" (Which ones) did he not install new bowl gaskets? Could the O'Ring on the screw for the drain tube be leaking. Do you have a performance problem, and do we actually have TWO issues that we are dealing with, the gas leaking and something not functioning properly inside the Carb? Some pics or a better description would be a great help here. Either way, I wouldn't let this guy wash my windshield much less mess with the Carbs. on your RSV.

Earl

[qdude]

Thanks for replies, it is 2004 RSV. On page 6-5 of the repair manual I was assuming he means the #13 the jet needle.

I would agree that taking it back is not a good idea.

 

I was concerned when he came up with such a quick answer. He certainly didn't catch the fouled plug or fix the problem in the first place. I am also wondering about what he actually did or did not do when he had the carb apart. My question to you was more if you thought his idea had merit, I doubted it so I asked.

 

I have seafoamed, but no avail.

Where I first see the gas it is by the flange bolt on the base of the carb the goes into the head. The gas follows the head gasket seem over until it runs down on the crankcase breather and off the side of the bike. It is not clear exactly where the gas is originating from. Doing a search I am not finding a common issue with others.

 

I am not certain if I tore it down myself I would recognize the problem unless it was fairly obvious. I have studied the parts manual and service manual and I'm reasonably sure I could remove the carbs without a disastrous fubar, but I don't really have a good place or lots of spare time to do this. Pinning down the probable cause would make the job much easier. I was hoping the description would bring a reply "oh yeah that happened to me too and it was...". Unfortunately for me I don't think many have seen this issue.

 

Skydoc thanks for the suggestions I will check the o ring on the carb. I have already drained the carbs but i will more closely check.

I have suspected a gasket leak but i guess until i take it apart or find a real mechanic I won't be sure. The performance does not suffer under load or at idle. The bike ran fine with the fouled plug and was getting 30 mpg, so the plug was partially firing. It runs much quicker and gets 30 mpg with the new plugs. The right front plug was definitely gas fouled and black while all others were tan.

Edited March 31, 2010 by qdude

[skydoc_17]

Hey John,

Thank you for a better description of your problem. I am now on the same page you have been on. Lets chat about general Carb. info. There are only a few places raw gas can exit a Carb. If this was a stuck float problem, raw gas would exit from the over flow tube and would be dripping back by the rear tire. This is why Seafoam did not solve your problem, because gas is not exiting the Carb. body from the over flow tube. Because the Carb. "bowl" on these Carbs. is pretty much the entire back side of the Carb. holding the float and float needle, I suspect that the Carb. Bowl gasket, (O'Ring) which is above the lower Carb. boot and flange (where the flange bolt is)This area is prone to leaking, and I believe this is where the gas is coming from. If you remove the Carb. Rack, you MAY (I have never tried this on a Second Gen. Carb Rack) be able to unscrew the float bowl screws with a right Angle Phillips Screw Driver or a 1/4" drive ratchet with a Phillips Bit in it and remove the float bowl and replace the O'Ring which is located on the bowl side of the Carb. (not the Carb. body side) You MIGHT (again, I say I have not tried this on a Second Gen.) be able to remove the Air Box and reach the Carb. Bowl Screws for the O'Ring change out. I would try this first before I remove the Carb. Rack. If you take this to a dealer, you will be into this for about $400.00 and I would get all 4 bowl O'Rings replaced at the same time.

Because I am poor, and it is hard for me to "walk away" from a challenge, I would figure out a way to get that Carb. Bowl off and change out that O'Ring, but that's just me. If your "paws" are as big as a bear, or a hammer is the first tool you grab when you go to fix things, then the money spent at a dealer to repair this problem might be money well spent. Just my thoughts, for what they are worth.

Earl