129 low power at full throttle

[Eric Wittersheim]

Hello all,

Let me set the stage for this. I bought a 129 that was a bit rough but not too bad. I could never get it to run smoothly, even after cleaning the carb, buying a new Voltage Regulator (the expensive one), changing the Points and adjusting them (to the best I could, never done it before), new Condenser, then finally buying a new carburetor from ISaveTractors. The new carb really helped the tractor run smoothly but now it really doesn't make power at full throttle. For example, you can start the tractor and let it warm up really well. Start going forward at full throttle then advance the hydrostat handle to full speed and the tractor will start bogging down and doesn't recover. This to me sounds like a governor issue, so I did the static governor adjustment (multiple times to be sure), I also adjusted the throttle cable (but not sure on the correct procedure for this). To rule out the hydro, you can also simulate the problem by engaging the mower deck blades and moving slower. I have also tested removing the air cleaner and loosening the gas take cap, neither helped.

I have not swapped the old carb back on to see if there's any difference but I do not recall having the low power issue before the carb swap. I've tried adjusting the high speed carb adjustment and I feel like I have it in the best spot. If I turn the screw in either direction it does not run as smoothly as it does where it's at. It's been pretty cold here, could that be the problem?

Other problems that may be clues.
1. The engine is pretty loud, it has a whining noise that is hard to describe but my 1250 or my buddies 122 are much quieter.
2. A little smoke comes out of the dipstick (is this blow by?) but not from the exhaust.

What do you all think? Tired engine, carb not getting enough fuel, something else?

Eric

 

[gary noblit]

Eric,are u sure "engine is whining"? I'm more inclined to think s/g bearing would be source of whine.If it's really bad it could be pulling engine down some..pwr issue might be timing or points setting as well...suggest ing leave point cover off and crank over to look for bright blu spark....an old timer trick: a couple ft of hose 1 end in your ear and use it like a stethescope and u can find the source of whine by touching various spots with hose end...

 

[Eric Wittersheim]

Eric,are u sure "engine is whining"? I'm more inclined to think s/g bearing would be source of whine.If it's really bad it could be pulling engine down some..pwr issue might be timing or points setting as well...suggest ing leave point cover off and crank over to look for bright blu spark....an old timer trick: a couple ft of hose 1 end in your ear and use it like a stethescope and u can find the source of whine by touching various spots with hose end..

Gary,
The whine could very well be the s/g. I do have a short hose that I use to winterize the RV that would be good for a stethoscope. I'll pull that point cover off tomorrow if it's not too cold and take a look. Thank you for the tips!

 

[mgonitzke]

Check timing and valve lash. If the timing is off, the engine will have no power but may otherwise run ok.

http://mgonitzke.net/cubcadet/tools/static_timing.pdf

 

[rfunk]

Matt's timing method . . . just plain works. I use the "buzz" continuity feature on my multimeter, making it slightly easier. I don't even look at points gap . . . when the timing is on, it will start and run the best. Watched one of those guys on YT recently who was trying to get something running after many years sitting, using ether, etc - you could HEAR that the timing was off. I learned to set timing by ear on some of my early cars, only used timing light for perfection.

 

[Eric Wittersheim]

Thanks mgonitzke and rfunk. I will try that again, I used that document before and must have done something wrong because it would not start after following the instructions. I looked at a video from ISaveTractors and was able to get it running. Timing would make sense since that was one of the last things I tried before the new carb.

 

[Eric Wittersheim]

Well, I have still not had any luck. I have swapped the coil, condenser, set the timing multiple times and trying different gaps from 22 to 18. I also cleaned out my original carburetor and reinstalled that and it still doesn't make full power. I pretty much at a loss. My only other idea is to take my gas tank off of my 1250 and install it on the 129 to see if it's a fuel flow issue. Otherwise, either I can't time it myself, or my engine is weak. I thought of trying a compression test but with the automatic compression release on the K301 that will not give good results.

 

[Greg Riutzel]

take my gas tank off

The gas cap may not be venting or venting well from debris. Try it with it loose and the level low enough to not splash out. If it's running lean, you can check the plug color as well.

 

[mgonitzke]

Have you checked the valve lash?

 

[gary noblit]

Eric, you did say "smoke from dipstick"..That's not a normal function.That could be very bad rings or as Matt said ,valve adjustment...Did you replace hoses? The old ones don't like alcohol fuel and break down severely inside.

 

[Eric Wittersheim]

Gary and mgonitzke, that is what I was reading last night. I have never torn into an engine before but I think I will have to with this one. The fuel hose is new as well as the filter. The gas cap is also new (from one of our sponsors) but I can loosen it and try to see if that helps.

 

[jack casey]

Gary and mgonitzke, that is what I was reading last night. I have never torn into an engine before but I think I will have to with this one. The fuel hose is new as well as the filter. The gas cap is also new (from one of our sponsors) but I can loosen it and try to see if that helps.

My two cents: I have a K241 engine. The cyl head bolts get torqued to 30 ft/lbs probably like other K engines. In my experience bolts #4 and #8 will loosen; when tightening them the engine ran better.
Cheers, Jack

 

[Eric Wittersheim]

Thanks Jack, that's something that's easy to try. I'll give it a shot.

 

[jack casey]

Thanks Jack, that's something that's easy to try. I'll give it a shot.

And replace the gasket which cud be 50+ years old.

 

[mgonitzke]

If you are going to take the head off to replace the gasket, sand it flat with 220 grit wet/dry sandpaper on a sheet of glass. Odds are it is no longer flat within 0.003" as specified in the service manual, and it will just blow again.

The service manual is a free download from Kohler's website: https://resources.kohler.com/power/kohler/enginesUS/pdf/tp_2379.pdf

Since the advice is starting to get a bit haphazard, we need to systematically eliminate things.

If the engine is bogging down/trying to die under load, pull the choke out slightly. If this helps, there is a fuel delivery problem. If it does not, the problem is elsewhere, and we can eliminate the fuel system.

Assuming the engine isn't totally worn out (and it probably isn't...I have found engines that are worn to the point of producing no power will smoke like crazy out the exhaust), issues like this are usually related to ignition or valves. So, after eliminating fuel problems, set the valve lash to the spec in the service manual. If the valve lash is too tight, the valves won't fully close and the engine won't develop power well. If they are worn or not sealing well, this will also cause issues, but I'd first eliminate other possibilities.

If you aren't certain you are getting the timing set correctly, get help from someone who can. If you aren't sure it's right, it will be difficult to eliminate that as the source of the problem.

Is the condenser on the points side of the coil?

 

[Eric Wittersheim]

Mgonitzke,
1. Pulling in the choke doesn't help
2. It's not smoking like crazy but there is some smoke
3. Agree, I was also thinking about taking it to a mechanic
4. The condenser is mounted next to the coil

 

[mgonitzke]

Item 4, is the condenser wire connected to the negative side of the coil- the same side the points are on?

 

[Eric Wittersheim]

Item 4, is the condenser wire connected to the negative side of the coil- the same side the points are on?

Yes, it's on the negative side.

 

[jpaulus]

Make an adapter to put compressed air in the spark plug hole. Then set the piston at TDC, lock it in place, and add air pressure to the cylinder. Now listen to the intake, exhaust, and dipstick for air. Feel around the head for leaks, maybe spray a little WD40 at the gasket area, and look for bubbles. There is such a tool as a leak-down tester. You can make one just look it up. But this will give you an idea of where you might be losing compression. you should hear NO sound at the intake and exhaust. SOME sound at the dipstick. NO bubbles from the gasket

jerry

 

[dkirk]

Have you checked the no-load rpm? Many complaints of low power are simply due to the no-load engine rpm being set too low. You will need an inductive electronic tachometer to check, such as the TinyTach. Adjust governor setting to 3600 rpm with throttle control in "full" position.