Kohler 400 problems...help...help!

[ArgoDude2350]

I've got a kohler 400cc motor. It is really hard to start, and when it does, it shoots gas out of one of the manifold pipes. Also, the motor seems like it is getting too much gas. Anyone know what is going on? Help would be great. Thanks,

[jasonk]

Does it have a walbro WDA1-1 carb or a tilly? Get it runnin & remove the vacume/pulse hose from the motor or carb end (seems easier at motor) & see if it stops spitting fuel out while it's runnin. It should run for alittle bit before it runs out of fuel. I had that problem & it was the carb. I got lucky & found a NOS walbro. You can remove the hose even before you start it, it might start easier without all that gas. With it runnin i stuck the hose back on to get it more gas then removed it again to see the change. Hope this helps. I do have 2 extra K3992T's 1 disassembled & i complete but stuck if you need any parts. I do not have a good carb. I bought a mikuni vm32s that i was going to use & buy the rubber mount/gromet before i found the nos 1 but kohler carb mounts straight down (atleast it was on the 2 i have. Good luck with your machine. JasonK from Pa.

[ArgoDude2350]

It has a Tillotson HR, but I just went through it with a carb kit. I tried starting it without the pulse tube, but it wouldn't start. My problem seems to be something in the motor. I had it running recently after replacing the head gaskets and had no problems. Now, it will run on one cylinder, with the occasional puff coming out of the other cylinder that all the gas comes out of. I don't think it is the rings because the cylinders are shiny and clean. I'm stumped and running out of ideas. I changed a set of spark plugs, but I didn't think that would make a difference, because it did the same on the last set of plugs. Any more ideas? Thanks!

[jasonk]

I do know that the lower crank seals have a lot to do with the vacume of the gas coming into the cylinder. My engine was racing at idle & i noticed the seal was bad, i could see the bearing around the where the crank sticks through. I changed it & now it idles/runs good. 2 strokes suck the fuel in & it all goes to the lower end to lube the crank first then it goes through the cylinder, it kinda cycles through. I saw a video illistation on the net somewhere showin it's "pulse operation" There's 3 seal, one on each end & a center one between the the rods on the crank. If you can get it started spray either around the both outer end seals/lower block ect.. & see if it races up. If this is not the problem maybe the points/condenser/coils could be bad. I have a complete plate with the points & everything if you need. Let me know how you make out. JasonK

[ArgoDude2350]

What it will do now is it will either fire and run for a moment, or idle until i shut it off. It will not accelerate. I've got new seals, so I'll try replacing them and the rings. Also when it idles, sometimes it will run on one. The one cylinder it runs on spits out a ton of oil. Too rich of fuel? The cylinder it doesn't run on spits some gas, but sometimes when it runs on one, it will start puffing and run on both. Other times gas will just drip out of the exhaust pipe. Sometime this week, I'll try replacing both the rings and the crank seals. I just replaced ALL electrical components in the machine. Anything else you can think of before I take it apart. I don't really want to have to pull the engine from the machine again. Thanks

[jasonk]

Do a compression test if you have access to the gauge. I'n not sure of the #'s it needs. I think it's around 100 & more psi. If it's at 90 or below it definatly will need the rings. Hopefully it's not out of spec on the bore & require oversize pistons. Did you check the coil wires to be sure it has good fire coming out of both? Especially the one cyl that seems to have the most trouble. I read you put all new points/condensors in it but what about the coil. I cut back on the oil as i had oil dripping out the pipe severly & smoked like crazy. I'm running about 36:1 & it's a lot better. Compression is key with the 2 strokes, the seals a another important factor. Having gas come out the pipe & if it's firing on that cyl it could very well be the compression is alittle low. Hopefully one of the old time members will chime in here & lend a helping brain cell. If you find out you need the coil i'll give you one. Let me know, JasonK

[ArgoDude2350]

Yeah. I put new coils in too. There is good fire coming out of both cylinders. When I do a comp test, should I test the ignition timing too? I'm currently running 32:1 in it. Too heavy? I'll get everything checked out this week. I'll try to get the new seals in it. Thanks.

[jasonk]

32:1 is heavy but more oil is better than less. Try cutting it back some & see how it is. You will need a timing light for the timing. I set mine at the factory notch(s) then you ca start from there to advance it. Both have good spark, sounds like low comp.. or a blown seal witch would act the same as low comp due to the way it sucks gas into the cyl. Good luck with the seals. The middle seal, the crank has to be pressed apart & pressed back together in time by a shop that does 2 strokes. The outer seals you may have to remove the motor to split the case(s) to get them in. Start with the comp. test first before replacing seals that may be good. It wouldn't hurt to just put the rings on & try it...

[ArgoDude2350]

Gonna test compression the first of the week. I probably one or the other. I'll replace both. Would 40:1 be ok? The comp is super weird though. Sometimes it will start and idle For twenty minutes. Other times, it won't. It will ONLY run with the choke. If I cut the choke or try to accelerate, it quits. Hmmmmm........

[jasonk]

Needing the choke to draw the fuel sounds like a vacume leak or low comp- since you rebuilt & cleaned the carb. Possably lower seals, around the intake/carb gasket or just low compression. With low comp it will be hard to start. Verify the compression first. If you do get it to idle, spay carb cleaner or either around the lower seals,case & around the carb where it mounts & the intake to engine & see if the rpm's increase or if it smooths out.

[ArgoDude2350]

I'll get a compression test on it before the end of the week. I'm gonna have to pull the motor, so I'll also try spraying the seals. I've had several people tell me now that it is seals or rings so I will replace both. Hopefully that will finish it up, considering I've replaced just about everything else in this motor. Thanks. I'll post by the end of the week what I found the problem was and the comp readings.

[ArgoDude2350]

Ok. I think I found out my problem. The plugs at the bottom of the crankcase were missing. Compression before replacing them...80 and 85. Compression after replacing...130 and 125 psi. I think that made the difference. I'll try o start it this weekend.

[Mpolly500]

That's a huge difference. It should start right up now. Let us know

[jasonk]

I think you found the problem too. They are the little brass threaded plugs i believe. They are where you can drain out the crankcase of fuel/oil. Amazing the difference in comp. The piston & rings sound great! A compression & vacume leak, both ideas like we talked about. You are probably thrilled it was something so simple?? Is the motor still in it? Talk to ya soon. JasonK.

[ArgoDude2350]

Yeah, it was those little plugs that are below the coils. Major difference in compression. I still have the engine out of it..mainly because I thought I had to replace the seals and stuff. I'm going to drop it in tomorrow and try to start. I was wondering why it was leaking so much fuel.....it was going straight through this plug holes. Glad it didnt cost me any more money. I'll post my results tomorrow. Thanks