could use some advice...

jake wilken · Post by **jake wilken** » Sat Oct 22, 2005 8:39 pm

I got my new carb kit for the 75JD and put it together and put the carb back on sled and it runs but not correctly. The sled will run all day if you dont give it any gas and have the choke cracked but if you close the choke all the way it will die out. and if you give it gas at the throttle it will make that deep raspy sound and bog out and die. I ran it for at least a half hour trying to run junk out of it and this didnt change anything. Its running on both cylinders, I pulled the plug wire off while it was running. The pulse line or vaccum line from the engine is pulling a pretty good vaccum and its pulling gas. I sprayed ether around the engine while it was running to see if the rpms would increase to check for bad seals and nothing happened. Im just trying to run thru some of the things I tried that were suggested to me. I tried adjusting the low speed and high speed idles but cant seem to get the sled to run that much differently. Dont know why its bogging out when I give it gas or why I cant close the choke all of the way. I'd hate to abandon working on the sled now because I figure if it runs it runs, it cant be that messed up, the lights and everything work and its starting to get cold here

Should I give up and take it to a mechanic? Or part it out? any suggestions would be appreciated........ Jake

jake wilken · Post by **jake wilken** » Sat Oct 22, 2005 9:00 pm

I forgot to mention its a walbro wr carb and I believe the engine says krh 340/22...

400brian · Post by **400brian** » Sun Oct 23, 2005 2:23 am

It is always dangerous to apply 4 stroke thinking to 2 stroke, but here goes.

On 4 strokes, it is fairly certain that if you have to run with the choke pulled out, you have a vacuum leak.

That may, or may not be applicable here, but it sure sounds like it is not getting a correct mixture when you open the throttle.

It can be hard to determine if you are too rich or too lean when all you can get it to do is idle. Have you tried misting some fuel into the carb as you open the throttle?

Jake, did you do a compression test on this motor?

JDFanPa · Post by **JDFanPa** » Sun Oct 23, 2005 2:59 am

Ok maybe your just saying things wrong but it should die if you close the choke. It seems the motor isnt pulling the fuel in through the intake and first thing coming to mind is bad crank seals. I have seen a motor with the crank seal popped right out that will pulse enough to pump fuel but wouldnt suck it in off idel.

Also something to consider is that although the carb is pumping the fuel up maybe its not getting through the carb like a blocked passege. Is there any fuel coming out the return line when you are ideling the sled.

jake wilken · Post by **jake wilken** » Sun Oct 23, 2005 7:18 pm

Ok bear with me Im really trying to learn here and appreciate everyones advice...

When I say choke closed what I mean is the "shutter" that open and closes for choke is closed so that you cannot see "inside" to second "shutter" that is controlled by the throttle lever. In normal operating condition I thought that the carb choke was supposed to be closed so that you cannot see inside. It will run if the choke is "open" so that you can see inside and it will run if you close it but not all the way closed thats when it stalls out. Maybe Im saying this wrong as you stated. There is gas coming out of the fuel return line while its running. I also did a compression test before I ever had it running at all. Cant remeber what the results were but i was told they were good. something like 140 to 160 across both cylinders. I also did anoteher compression test after I had it running for a while because someone told me to do this to make sure I didnt lose compression with a stuck ring or scored cylinder walls. This test gave me results similar to the first one. Maybe im thinking backwards and should be running with the choke shutter wide open? Even so I tried this and Im pretty sure it still bogged out when I gave it gas.

harleysportster · Post by **harleysportster** » Sun Oct 23, 2005 7:31 pm

Jake,
The choke is used to start a cold engine. To use the choke, the cable is pulled out of the dash(butter-fly type carb ) or the dash lever is flipped up( mikuni type). When the choke is applied as mentioned, the choke butterfly( baffle-plate) is moved to close off the opening. Once the engine starts, you need to slowy open the choke to smooth out the engine. Within a few minutes the choke should be completely off
( the butterfly plate is fully open)
It sounds to me that you are using the choke backwards which is causing a rich condition, bogging out and dying.

400brian · Post by **400brian** » Sun Oct 23, 2005 7:34 pm

Jake

Yes, you should have the choke butterfly OPEN to run. Open means you can look inside and see the throttle butterfly ( button pushed in on dash ).

Generally, it will take full choke on to start, then full off shortly thereafter.

Hey we're making progress now.

jake wilken · Post by **jake wilken** » Sun Oct 23, 2005 9:08 pm

yes I have been trying to run it "backwards" and as far as everyone saying what positiion the lever is on the panel or pulled out I cannot tell because Im missing this and will have to order one if I can get it running correctly

But boy do I feel stupid trying to run it that way. I should have known better, I dont know what I was thinking

:blink: guess I wasnt... Ill go out and see what I can do tomoroww and let everyone know..... Your help and promp replies have been great and truly appreciated. This site reminds me of another forum I use for my farmall cubs.

Jake

JDFanPa · Post by **JDFanPa** » Sun Oct 23, 2005 10:25 pm

Good luck Jake I think we have gotten to the bottom of this one

jake wilken · Post by **jake wilken** » Mon Oct 24, 2005 9:16 pm

tried running it a little tonight and while it ran at idle it still bogs out when i give it gas. Im wondering if its not getting enough gas to carb from tank. Right now Im using temp gas lines and a tank and think that this might have something to do with the problem but Im not sure. Im also hoping that the local napa will have a check valve I can put in the line. I ran a clear line tonight from carb to tank and had to pour some gas into it to prime it and when I stuck the end into my gas can and ran the sled it stalled out because it was trying to suck gas and there was a air gap in the line. How will I get around these air pockets and should the line be totally full of gas all the way to the carb? Im really hoping that this is the problem. and then I can get to fine tuning it. the hose Im using right now is a little big but I have it clamped pretty tight I thought. Ill try to get correct gas line (1/4'' im assuming) and a check valve but that still doesnt solve my air pocket problem. I dont know if this is supposed to just run through the carb or not. Maybe I could get it to with a check valve

:unsure:

400brian · Post by **400brian** » Tue Oct 25, 2005 12:54 am

Get the correct 1/4 inch line, clear, so you can see what's going on.

If the fuel pump is working right, it will pull fuel right up, no priming needed.
The bubbles in the line are not causing your problem, unless there is a stream of them, which would indicate a poor connection somewhere.

The check valve will help, but I doubt it will be a cure for what you've got going on.
It sure sounds like you're not getting enough gas yet.

Did you have a good exploded view of how the carb goes together?
It might have been assembled wrong when you took it apart, unless you know it ran in the past.

Maj_hazard · Post by **Maj_hazard** » Tue Oct 25, 2005 2:56 pm

I had a similar problem with my sled but with a slight twist.. it would start and idel OK.. It would even run fine un til the engine warmed up a bit.. Then it would only idle and gave that same boggy noise when you hit the gas.. The problem ended up being my high speed adjustment was way to rich.. Just something to watch for

CHeers

Mike
JD 73ish 300

JoeRainville · Post by **JoeRainville** » Tue Oct 25, 2005 5:28 pm

Hey Guys,

Two things to add here. First, you should have an fuel pick up "inlet filter" on the bottom of the line that goes into your fuel tank. It has a check valve built into it, as well as being a filter. ALL sleds use this, including new ones. They are only a buck or two at any dealer.

Secondly, once it gets cold out, you probably need to adjust your jets on the Walboro. I am not sure of what model you have, but most of them had a 'Hi Speed' and "Low Speed" adjustable jet. The repair manual for your sled has the proceedure for dialing it in and getting rid of the bog.

But, bogs can also be cause by a worn drive belt (80's Liquifires are very sensitive to work belts for example), or clutching issues.

Good luck with your sled,
-Joe Rainville
"Tech-Ed"

81spitfire · Post by **81spitfire** » Tue Oct 25, 2005 10:16 pm

we had a yammy that did that and it ended up being a head gasket.