108 carb
 

My machine ain't running so good. It will start but will not run for long and definitely seems like a fuel issue. I can't quite get it up to full idle speed (and there's a trace of dark smoke) so as soon as I engage the mower deck it bogs down. I pulled the air filter and noticed gas droplets leaving the throat. Is it time for a rebuild, or are there things I can try short of that?

I would start with a carb rebuild.

Along with carb rebuild check the throttle shaft for play.

Sounds to me like it's sucking air someplace.

Sounds to me like it is too rich. Try turning the main jet in a quarter turn.

2 votes for carb rebuild

1 vote for too lean

1 vote for too rich

Sounds like a tie. :biggrin2:


So.... who do you believe??


I'd rebuild the carb, just so you know what my opinion is. :ThumbsUp:
But hey, I'm just another vote right?? :bigthink:

I also vote for the rebuild, plus you might as well clean out the tank and lines while you are in there!



Randy

Well, that makes 3 for the carb rebuild. I've also become aware that I have no inline filter, and I probably should rectify that.

i don't run an inline filter on my 108, the tank has a screen in it and as long as everything is clean it shouldn't be an issue.

I ran my 108 for over 30 years with no inline filter. Rebuilt the carb every 7-10 years or so. Bi-weekly 2 acre grass cutting machine. Most of that was with non-ethanol fuel. Nowadays, ethanol fuel really messes with anything that's not in constant use.

oh yeah...looks like a gravel pit inside this carb...:biggrin2:

No, it's 4. You counted wrong.


Make sure that the sediment bowl has a screen in it. If not, add a filter, or replace the bowl. I suggest replacing the sediment bowl. They don't require replacement like a filter, just a cleaning. After 40 years they do get a little corrosion on them though, so I usually replace them and start over. A sed bowl is better IMHO, because it also traps water, and you can see when it needs cleaned.

X2 --old technology that works great!

I agree with other posters, rebuild the carb. For me, I go on the cheap and spend as little as possible at first just to get the engine running.
I have a few cubs and do this on each one at first. Pull of engine and save all linkages. Make note of where they go. Remove both low and high speed jets, pull of bowl, float and needle valve. Soak in carb cleaner solution / clean Clean all parts and especially fuel delivery and jet holes in carb with compressed air ( if possible) and and brake cleaner. Re-assemble and adjust jets to 2 to 2 and 1/2 turns from fully seated. Engine should run (that's been my luck) but you will need to fine tune the jets.

Above all things, install an in-line filter. This is cheap insurance and will keep the engine starting all the time. Ethanol fuels will clog up systems.

Once the cheapy-fix is done on the carb and your satisfied that the engine at least runs, then spend the money on the carb rebuild kit. Also another poster mentioned it, air could be coming in to the carb body through worn throttle plate bushings. Air should only come in through the air filter and not from any other part of the system.

Not true at all.... Ethanol breaks up loose gunk and can eat up old hoses not made for the alcohol, but ethanol itself is not to blame. A dirty fuel system is. These engines are carbureted and have metal fuel tanks. The only thing that may not hold up to ethanol is the fuel hose.

I been using E10 for 15 plus years with no fuel related problems.

I agree with J-Mech response below.

#$@# store gave me a Kohler 12 757 01-S kit

Thats not the right one, is it? :bash2:

That';s OK, its only 50-60 miles round trip to get another...:bash:

Since I cant get to the shop for days and the grass is knee high, after a good soaking and spraying with carb cleaner I put it back on. If anything, its worse now. It ran briefly but then died. After cranking some more fuel was spraying out of the choke again...

Well it turns out the right kit doesn't really have anything in it anyway, just a bowl and bolt gasket. I've now cleaned the carb twice and also cleaned the tank (screen was good) and installed an inline filter. the needle looks good under a scope and it seems to seat and seal. I've cleared the gas from the cylinder after each try but now it won't start at all. I've started with both screws at about 2.5 turns out and backed them out from there. Still think I'm getting too much gas, but it isn't coming out like it was before. I've got spark.

Whats my next step, experts? How do I check the float level?

if your 2.5 turns out and getting to much fuel then turn it in, id go to 1.5 turns out and go from there.

Should have set the float level while you were rebuilding it. :bash2:

If it's flooding, stop choking it.....

Main needle setting doesn't really affect starting. Not enough vacuum to pull from that hey until higher RPM. I'd leave it alone.

No, I counted all the votes that count. :BlahBlah:

?? :bigthink:

Just because it's free and easy, take the high speed needle all the way out.

Check all of the little tiny holes in it to make sure they are clear. That needle is also hollow and the inside needs to be clear of any obstructions.

Yeah I pulled that bad boy out and confirmed what I suspected. I need to do a better job rinsing off the carb dip residue and cleaning the whole system at one time. It wasn't clogged but there was spooge on it, and there was scale in the hose. At last check I'm now not getting any gas at all...time to do it for the third time, only right this time.

anyone want to clue me in on the float level since I've got it apart? I don't expect its changed much as Uri Geller has not been in my garage lately, but its worth checking if not too troublesome.

I realized my earlier comment about counting only "the votes that count" could have been misconstrued by other great and respectful members of this community and I don't want that. I don't want anyone else to wonder if I was referring to their votes not counting, because I was not. You may be the best mechanic in the world but I find arrogance off-putting and so it's your vote that I didn't count.

With the float installed on the carb flip it upside down and the float should be parallel with the float bowl seat. There is a manual in the tech section that lays out the whole procedure of rebuilding a carb as well as settings. Make sure all of the old carb flange gasket has been scraped off the engine and carb flange. Plays heck with how they run. OOPs quoted wrong post.Post before this one should have been quoted.lol :bigthink::bigthink::bigthink:

I love it when people who need help reject information because they don't like the delivery. Believe me, I could care if you fix your tractor, or have to take the carb apart 10 times because your too lazy to read a service manual that outlines how to do it. Good luck.

:BlahBlah:

Thanks! I'll look for the manual of which you speak.

I'm still stuck. Since I damaged both the needle and jet/nozzle I bought an aftermarket carb that has a POS needle. I still have the same problem as ever. Gas to carb, gas runs out of carb, but spark plug is dry and no start. But if the main needle isn't involved in starting I don't knmow what to do. I'm ready to dump this thing in the lake.

Is the fuel cap on when this happens.
 

Just a quick question, from the last post. You said you put an new aftermarket carb on it and it still leaks fuel from the carb. This is just a guess, but does it do this without the gas cap on? Sounds like maybe you are pressuring the fuel to the point of over coming the needle seat. Leave the cap off and let it sit to see if it still leaks. If the cap is not venting correctly, it is possible the the tank is building pressure and foring fuel by the valve.

What I mean is the carb spits fuel out when I crank it. Usually its on the last crank just as I release the ignition key and I see a pretty good splash of fuel spray out. But the plug is always dry.

One other thing I can think of right off the top of my head is the valves. If the intake valve is not closing all the way on the compression stroke it will do the same thing it will be pushing air/fuel mixture back out of the carb. Something to check.:bigthink:

X2 for possible stuck intake valve causing your issue.

Sounds like a good idea. Any instructions anywhere? I've only done valve adjustments once, on my old Kawasaki.

http://www.onlycubcadets.net/forum/s...ead.php?t=4646

:biggrin2:

I've got the breather cover off, but its not obvious to me how to get the rest of the breather assembly off. The one in the service manual illustration looks rather different than mine. There is a thin plate apparently mounted to the stud but I can't see how its mounted or how to remove it.

Slides right off the stud. There's a rubber spacer in front of it that will come off the stud. Just remember the order or everything and orientation plus the oil drain hole. Everything slides out behind the cover individually

Yup, thanks. It all came out as one piece though. At any rate I'm down to the tappets now and I just need to find TDC. better wait till morning for that though, or I'll find a way to screw it up