Walbro carb issue

[Recoil]

Hey guys...i started a conversation on the new members thread that likely belongs here instead.

The issue is on the wlabro wr 7-5 carb on my 72 400. To summarize the entire story i wrote on the new members area....

Bought old sled, replaced everything i needed too and cleaned carb. Replaced some worn baffles and gaskets with new ones and now sled floods badly each time i try to start it. Gas will often pour out of the darn thing. I really cleaned this carb well (5times).....better than any other carb cleaning i have done. Not sure what else to do. I have never replaced a metering value before and i wonder if, after years of sitting, the little rubber tip dried up a bit. Anyone know if this may help? Anyone know where i can get this valve? Last question....anyone notice a difference in the fuel pump baffle that is sold in the kits now a days? The center "button" is much thicker and i assume that means it would affect the metering value contact....thought?

Please help.


Recoil

[Matt]

I feel like we have had this discussion about the metering plate/gasket before. I did a search and it turns out we have, several times. 400Brian was just having the same issue last winter, maybe he can tell us what ended up happening. I personally can't remember what I've done. I know I do the metering plate facing down, which is some times a point of confusion since the paperwork never says if it goes up or down, but I can't remember what I did with the gasket.

http://www.jdsleds.com/community/viewto ... &t=13391&p

[Recoil]

I had a bit more success today although it still isnt running great. I set the metering flange so it was JUST flush with the carb housing. I also have the fuel baffle AND the new gasket in the rebuild. Seems to be working a bit better. Still though, any other comments?

Recoil

[400brian]

I had the same issue with a carb off a '72 400 last winter as Matt mentioned ( the one pictured in the banner at the top of the page ). I later tried an original 40 year old carb, and had it running without spewing fuel out the throat. I'm not talking about the usual piston port fog at the throat, but liquid running out.

I don't know what is different, but it seems you really have to set the metering lever down to make the new rebuild kits work. I prefer the Windrosa kits over the SPI. I have measured the gaskets and diaphragms in the Windrosa kit, and can't find much difference, so I can't explain the problem. Lower the lever until it works I guess, and of course adjust the idle mix. You have to get these engines hot to really set the carb, idling in the garage doesn't really work, you need a couple of hot laps around a field.

[Recoil]

Thanks for the info Brian. Having to get the engine hot is an interesting and useful bit of info. In all my other vintage projects i have not had a CCW engine so this is a first and info like that is useful. Anyways, do you know if there is suppossed to be a fuel baffle AND a gasket or is it just the fuel baffle? The explode diagram only shows the fuel baffle but my carb had a gasket in there when i took it apart and there was one for it in the rebuild kit.

It is running not too bad today. What i did to get it going was washed...no...SCRUBBED the carb spotless (5 times!) and then set the fuel metering lever so it was just barely under flush of the carb body. That seems to have compensated for the larger "button" on the replacement fuel baffle.

So far so good.

Matt, last question....i have never run a JD before so wondering....is there a high pitched whine when running these machines? It isnt deafening and i am not lacking power or feeling weird drag so i am just wondering if that is the normal sound.

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[400brian]

Recoil

The high pitched whine is particular to the '72s and probably the '73s.

Those early engines used a different fan arraignment from the later CCW/Kioritz engines. The 340 in particular screams pretty good. Also there is no airbox, or any other sound abatement that was used on the later models.

I'm not positive what you are referring to as a "baffle".

Here you see both a metering diaphragm and the gasket. I've measured the button, but don't recall a significant difference from genuine Walbro.

[Recoil]

Well i had the old girl out for vintage ride today and it is working great! The trick that worked for me was...

The metering baffle replacement has the larger "button" in the middle of the metal disk. If you look carefully, that button is exactly where it makes contact with the metering lever to lift the needle. The specs say that the lever should be just barely over the body of the carb when measured with a straight edge (or the fancy measuring tool if you have one). I measured the difference between the old disk and the new one and guesstimated that due the the larger button, the new setting should have the lever just BELOW the carb body. I bent it (tech manual says to bend it at the needle end NOT the lever end) accordingly and presto....she worked. No more fuel pouring out of the carb. I bent it so it is now below he carb body as much as it was above it before. It is JUST barly below.

I am going to take some photos tomorrow and post them. Glad i figured it out because it is a fun vintage ride. Thanks or the help guys.

Paul

[400brian]

Success is sweet! Glad to hear you've got the old girl making smoke.