Kohler 440 - 2AX troubleshooting advice

[micmac]

My Kohler 440 has developed an issue that I need to help figuring out. The problem started back at Phillipsburg with hard starting and seeming to idle only on one cylinder. It bogs coming off of idle and then there is a change in the exhaust note (like a puff) and the other cylinder comes to life. Top end power is good.

I have changed the plugs and plug wires. I've gone through and cleaned both Mikuni carbs making sure everything is clean I even made sure the pilot system was cleaned out with a fine wire. The fuel lines are all new and I checked the fuel pump and that's clean. The carbs are synced as far as I can tell. I changed the crank seals and head gasket recently. I tried spraying starting fluid in the seals with no rpm increase. It was timed and compression checked so unless something happened in the few hours I've run it they should be good.

That's about all I can think of. Let's hear some ideas!

Mike

[LarryW]

That sounds exactly like an issue I had with a rupp tr340. It ended up being the coil under the flywheel that charges the main coils. It would work/not work when it felt like. Run like raped ape and then dog. I followed the 2 wires going to the main coils and swapped them. Then the other main coil wasnt working proving to be the coil under the flywheel. Just an idea to check. My brother bought me a spark tester for a present once that plugs into the coil and the spark plug. You can see the spark. If you get one of those you can actually run it with it on and it helps eliminate the problem easily. When it runs bad take a look and see. If not, swap cylinders and check that one. He got it a cheap supply store local called B&G discount glove but probably can find it at harbor freight or similar. Good luck with finding out what it is. Once you found the problem. rest is a piece of cake.

[wildtexasranger]

Yepp What he said .

I was thinking the same thing LarryW was thinking, you might also want to check your fuel cap. Sometime the vent gets clogged and Ive seen it do the same thing.when it starts doing the same thing again just crack the gas cap some and see if that fixes it. if so just get another gas cap !!!!!!! also check all your wires back to the coil and make sure its not shorting out.all it takes is a pinhole to short it out.You can also check the coil and see if its weak.If it was me Id also run an compretion test. ( both sides) to see if they are close to each other.Good luck..

[micmac]

Thanks guys I was thinking coil as well. WTR I'll check the cap too. This has the external coils that the spark plug wires attached to and additional coils inside the flywheel is that right? Don and I had it apart to time it but I cant remember.

[ES-hustler]

That's about all I can think of. Let's hear some ideas!

Mike

Before diving into the motor, I was thinking about the fuel lines. How do the lines run from the pump to the carbs? Are you using a single line out of the pump with a "T" junction to split it? Maybe the angle is such that fuel is only flowing to one carb because there isn't enough pumping power to send it to both at low rpm. Just throwing that out there.

[micmac]

Before diving into the motor, I was thinking about the fuel lines. How do the lines run from the pump to the carbs? Are you using a single line out of the pump with a "T" junction to split it? Maybe the angle is such that fuel is only flowing to one carb because there isn't enough pumping power to send it to both at low rpm. Just throwing that out there.

Mike,

It's a mikuni pump for dual carbs so I dont think that's the problem but I will check the flow to each carb.

Mike

[cobalt]

Hi.

I does sounds like the coil. However it could also be a vapour lock and the time it takes to split the tiny bit of fuel between the carbs could be the problem.

There might be fuel i the lines and the pump works. However there might be a vacuum that is providing a counter force on the fuel.

You could simply remove the sparkplugs and leave them attached to the caps and let them sit near the head (metal) and try starting the engine for a second to see if there is any spark, how much spark, and the spark sequence.

Granted it is an old school trick. However it is still works.

I made a fuel line tester that is simply two small beer bottles fixed to a board with stopers and hoses that i can attach to the carbs or efi (directly). I marked the bottles with measuring lines.

I drilled two holes in the bottoms of the beer bottles and placed some small metal aquarium valves the control the amount of air going in.

You can use a couple standard plastic coke bottles. So long as you properly clean them out before.

Good "process of elimination" tool to have around. Not to mention useful for precise engine cleaning.

[micmac]

progress

Some more info:

I changed the plugs after Phillipsburg before I replaced the plug wires and still had the same problem. I installed new wires and still the same problem. Today I started the engine with alternating plugs out to find the dead cylinder, turns out it was the right side, it still had spark though. I installed another new plug and now it 's running great. This cylinder had a bad plug wire and maybe the first new plug got fouled for the short time it ran on the bad wire . If it happens again, which is likely, at least I'll know the offending system. I may just replace the external coil just because thats easy and cheap.

Mike

[MarshallEpp]

Sounds Like An Old Kawasaki Motor Cycle I Had 3 Cly 2 Stroke.the Float Would Stick In One Of The Carbs And When It Cut Lose You Best Be Holding On. 500 Cc

[spits]

Probably is a coil but if that's not it try checking your output side(clutch) seal. That was a bad area when i was playing with sleds. The problem generally occurred after the machine was not used for a while, but not always.

[Amphiman1]

440-.....

Warped cylinder? or head? rings shot?

[micmac]

Warped cylinder? or head? rings shot?

I sure hope not Steve! That would not be good.

Don and I checked the compression when we did the timing and I think both cylinders were in the 160's. it has L rings if that matters. The engine has only run for maybe 1 hr total since the check and I don't see anything scary on the piston top.