1450 backfire and timing issues PLEASE help!
 

Ok I am about to go nuts.LONG POST WARNING. I bought a very clean 1450 with a hydraulic lift,headlights and a 50" deck two weeks ago. The PO had owned this tractor the last 15 years. 12 years ago He rebuilt the engine and used it very little and it mostly sat in the garage after he moved to a smaller yard. Before putting it up for sale he got it out and mowed with it several times. While up for sale it began to miss and run rough until it finally would only backfire out of the carb. He had messed with the carb and points until he gave up and reduced the price. I purchased it and all it would do is backfire out of the carb. I rebuilt the carb and installed a fuel filter because it didnt have one. Bought new factory Kohler points and used the static timing method to set them. The engine initially fired up but appeared to be flooding and only ran about 45sec to 1 minute. After that it ran less and less until it began backfiring out of the carb again to the point it blew fire out of the carb. I rolled it out in the dark and observed the points and noticed very intermittent and irregular fire. I went back to check the timing and it was off. I replaced the condenser and went through the process of static timing again but I can not get the same setting more than one time on the points using the static timing method. I am going to have someone more familiar with points check it but I am looking for suggestions from you engine gurus as I am just learning. Thanks Don

I don't understand how you know that you aren't getting the same setting using static time method. Do you roll the motor around and check it again? Try and start it and check it again? ....... :bigthink:

Did you check valve adjustment? Sounds like maybe the intake valve is not closing. Adjust the valves and see if that helps.

J-Mech,
Yes if you set it using the guide on OCC roll the engine over and check the "S" and then roll it around again the points will not match up to the "S" again. I may not understand these little engines but shouldn't the points be at the same spot every time to match the "S"? I havent checked the valves but until I get the static timing right checking the valves wont help? I may have to start and reset/check every setting on the engine. Also it will not start at this point only backfire through the carb.

I don't understand what you mean by "same spot". You mean just by looking at them?

Once you set them, yes, just as the "S" appears in the window, the points should just start to open. But it really isn't something that is easy to see. Oh, you probably could, but you really should use a meter or test light. I use a test light. Can't mess it up with a test light. I really don't think using a DVOM is a good way. If you use the test light it will light IMMEDIATELY when the points open. I'm assuming yo are using the guide that Matt G. made, right? If not could you post the link?

Im using Matts guide and my meter with sound. As soon as the points open NO beep should be the same as using a light. This is were I get varied results regardless of what I set the points at:
Now, rotate the engine VERY SLOWLY by hand in the direction of normal rotation (normally clockwise facing the flywheel). When the points just begin to break (open), the meter will fluctuate between zero Ohms to infinite resistance. When this fluctuation occurs stop rotating the engine and look in the sight hole to see where the "S" mark is located relative to the hole. If you performed this step correctly, the "S" mark should be centered in the sight hole at this time (as shown in Figure 6).
Like I said I maybe missing something but its pretty well explained and easy to follow.

Ok, so you are going by the sound. How far off is it? Like is the "S" even visible? Or is it WAY off?

I guess it would make more sense to say set on .20 the "S" doesnt line up so I move to .18 and reset everything. Logically the "S" should move closer to the center mark and eventually I should be able to reach a setting that results in the correct timing by follwing the adjustment procedure. However so far I have not been able to get any consistenty.

At .20 my "S" is above the line. At .18 I can not get a consistent reading on the "S". At .15 it is way way below the line. Sometimes I can go through a complete revolution and even thought the points appear closed NO beep. These are brand new points but its like they wont come together enough to trip the meter.

OK. Stop. I got it now. Here's the problem. The points aren't getting set on the top of the base circle of the cam lobe. Put away the feeler gauges. Put the "S" in the window and set it with the meter only. When it quits beeping, lock the points. Roll the motor and check it WITH THE METER ONLY and see if it's the same. Forget the feeler gauge it's throwing off your setting and they are not necessary.

Oh, and you should file the new points with either some emry cloth or a point file before setting. Clean them with a dollar bill folded three times while they are closed.

That sounds very logical actually. I did clean them like you said after the initial start up before this go around of timing. Ok just to double check. My meter beeps when the points are closed. So right now they are at an initial setting of .20 so move them closer until I get NO beep and the "S" on the center line? Correct?

Yes, that's correct, but let me say it differently..... (I think we are on the same page.)

Set the "S" in the window, then set the points closed. Hook up the meter, adjust the points until the beeping just stops. Lock them in place. It should hardly look like they are open, if you can see they are at all. But the meter should not beep. Roll the motor by hand with the meter hooked up. The meter will beep constantly. Just as the beep stops, check to see that the "S" is in the hole. It should be dead center in the hole. Then, they are correct.

Ok Thanks Ill try that and see what happens. Go back to work tomorrow so it will be a day or two before I get a chance to test it. I think the whole running issue started from dirty fuel and no fuel filter and the PO adjusted the points instead of cleaning the carb and things went down hill from there.

Good luck! I think I'd still adjust the valves. :beerchug:

Ill read my repair manual and tackle that also. Any hints you have send my way.

always roll in direction of engine rotation. if the cam end play is wide it will alter your timing location. Helical cut gears will do that

dvogtvpe,
For sure going in the right rotation. So far J-Mech using your suggestion I am getting consistent results with the points setting and the location of the "S" timing mark. Also I did check the valves they are not sticking and the gap is correct. I still have to double check all of the wiring. Ill do a test run this weekend once Im off work.
Don

J-Mech just wanted to let you know I timed it using you suggestion and replaced the condenser and wire and it fired right up. Runs pretty good. Thanks!

:IH Trusted Hand:

I need to replace the points on my 800 next spring. Last time, engine seemed to be misfiring a LOT.

With my big magnifying glass, stationary contact appeared to be cracked.

What is the best way to roll engine by hand? Remove spark plug to eliminate compression? Looking at engine from driver seat, it turns clockwise, right?

Been a while since I did major work on an older Kohler engine.

Thanks to all

you have the correct rotation--clockwise sitting in the driver's seat, looking at the flywheel. Or, counterclockwise standing in front of the tractor, looking at the PTO. It's easier to turn it over with the plug removed. I usually just grab the PTO basket or starter belt and turn it by hand.

The 800 is a QL. It doesn't have a PTO basket or starter belt. When I first read this, I thought the same thing..... then remembered what tractor it was.

To rotate the engine probably the easiest way is to pull the tunnel cover and turn the driveshaft with a pipe wrench, or channel locks. It rolls easy with the spark plug out. Might even be able to do it by hand. :beerchug:

Thanks a bunch,guys. I have the blades & spindles off my 38A deck, just hafta get time to overhaul them.

Cubby Guy

Doh! Of course, no belt or PTO pulley to rotate.