Backfire

[Dan.gerous 2,696]

Low to medium revs no problem at all, but it still pops and farts at high revs. I did it with a loaded trailer of firewood to give it a bit of stress.

 

So not perfect but getting there.

 

 

[ZXT 2,401]

Yes, you can order a condenser from anywhere. Pretty generic.

 

I may have asked this already, but have you inspected and set the points? I'd do that while I was at it. 

 

Did you adjust on the high speed adjustment screw any while it was doing that? Might just be lean.

[Dan.gerous 2,696]

9 minutes ago, ZXT said:

Yes, you can order a condenser from anywhere. Pretty generic.

 

I may have asked this already, but have you inspected and set the points? I'd do that while I was at it. 

 

Did you adjust on the high speed adjustment screw any while it was doing that? Might just be lean.

Hi ZXT, no I didn't touch the points at all, will have to look at that today.

 

I think I adjusted the high speed screw. I ran it at full revs and then turned that until it stopped backfiring, might have to go a little further as it started doing it again after I went for a long run around the farm.

 

It had been running perfectly for most of the run, only started messing about towards the end where I had to play about with the choke to keep it going for a bit.

 

All a case of trial and error, mostly error !🙂

[Dan.gerous 2,696]

It's messing about again, hard to start, backfiring, not idling.

 

I notice that the condenser is quite hot, not sure if it should be.

 

Also noticed that the fuel tank looks terrible inside, sludgy. I wonder if it has already sucked muck back into the carb. There is no fuel filter, so I had better get one ordered and see if that helps as well.

 

Will get there in the end.

[953 nut 55,066]

16 hours ago, Dan.gerous said:

I didn't touch the points at all,

Setting the points will help because they also adjust your ignition timing.

Ignition timing on Kohler engines.

 

Gapping the ignition points at .020 has always been the standard answer to how points should be set. That probably will get you into the ballpark where the engine will run, but with a bit of additional effort you can improve the engine’s power and performance.

The Kohler engine manual in the Red Square files section covers two methods for setting the ignition timing, Static Timing and using a Timing Light. This manual is a relatively new manual and it overlooks the fact that many of our engines were built prior to the ACR (automatic compression release) camshaft.

Earlier engines (mostly 1965 and earlier) had a Spark Advance camshaft that can not be timed using Static timing. At rest (and very low RPMs) the timing is retarded to fire slightly after TDC. The timing mark (SP) on your flywheel is at twenty degrees before top dead center but at rest the points on these engines break about ten degrees after top dead center. The only reliable way to check or set the timing on these engines is with a timing light.

There are a couple ways to determine what camshaft you have. Presuming the camshaft in your engine is the one it was born with the data plate on the engine has a suffix that can tell you what camshaft was used. The table below will tell you the suffix applicable to your engine. The other way to determine what camshaft you have is to remove the cam gear cover and take a look. If you see a mechanism attached to the cam gear it is the ACR cam.

 

 

The following engines have the spark advance camshaft;

K-141, Suffix prior to “C”

K-161, Suffix prior to “J”

K-181, Suffix prior to “D”

K-241, Suffix prior to “D”

[Dan.gerous 2,696]

7 minutes ago, 953 nut said:

Setting the points will help because they also adjust your ignition timing.

Ignition timing on Kohler engines.

 

Gapping the ignition points at .020 has always been the standard answer to how points should be set. That probably will get you into the ballpark where the engine will run, but with a bit of additional effort you can improve the engine’s power and performance.

The Kohler engine manual in the Red Square files section covers two methods for setting the ignition timing, Static Timing and using a Timing Light. This manual is a relatively new manual and it overlooks the fact that many of our engines were built prior to the ACR (automatic compression release) camshaft.

Earlier engines (mostly 1965 and earlier) had a Spark Advance camshaft that can not be timed using Static timing. At rest (and very low RPMs) the timing is retarded to fire slightly after TDC. The timing mark (SP) on your flywheel is at twenty degrees before top dead center but at rest the points on these engines break about ten degrees after top dead center. The only reliable way to check or set the timing on these engines is with a timing light.

There are a couple ways to determine what camshaft you have. Presuming the camshaft in your engine is the one it was born with the data plate on the engine has a suffix that can tell you what camshaft was used. The table below will tell you the suffix applicable to your engine. The other way to determine what camshaft you have is to remove the cam gear cover and take a look. If you see a mechanism attached to the cam gear it is the ACR cam.

 

 

The following engines have the spark advance camshaft;

K-141, Suffix prior to “C”

K-161, Suffix prior to “J”

K-181, Suffix prior to “D”

K-241, Suffix prior to “D”

Will get that downloaded.

 

Don't have a timing light or any clue how to use one, but now might be the time to learn.

 

[Stormin 9,981]

  Dan. If the tank looks dirty inside, dirt will be getting from there to the carb. You'll need to remove it and give it a good washout. Also make sure the fuel line is clean.

  Good Idea to fit an inline filter. There is a filter attached to the fuel tap, but that could be damaged.

[Dan.gerous 2,696]

1 hour ago, Stormin said:

  Dan. If the tank looks dirty inside, dirt will be getting from there to the carb. You'll need to remove it and give it a good washout. Also make sure the fuel line is clean.

  Good Idea to fit an inline filter. There is a filter attached to the fuel tap, but that could be damaged.

 

What would be the best way to clean it out?

 

[Stormin 9,981]

  Remove the fender and then you can remove the tank. 15 minute job. Put some small pebbles in the tank and pour some diesel in. You'll have plenty of red being on a farm.

   Give it a good shake about, or pop it into a cement mixer, then empty. Repeat till all dirt is out.

 

[Dan.gerous 2,696]

12 minutes ago, Stormin said:

  Remove the fender and then you can remove the tank. 15 minute job. Put some small pebbles in the tank and pour some diesel in. You'll have plenty of red being on a farm.

   Give it a good shake about, or pop it into a cement mixer, then empty. Repeat till all dirt is out.

 

Well give that a go on the morning once my wife let's me away from farm maintenance - the downside of being married to the manager and having lots of time off from my actual job.

[ZXT 2,401]

6 hours ago, Dan.gerous said:

Well give that a go on the morning once my wife let's me away from farm maintenance - the downside of being married to the manager and having lots of time off from my actual job.

I've always either used a short piece of chain or a number of 1/4" nuts. Pebbles ought to work as well.

 

Tank shouldn't be that hard to clean out being plastic.  

[Dan.gerous 2,696]

2 hours ago, ZXT said:

I've always either used a short piece of chain or a number of 1/4" nuts. Pebbles ought to work as well.

 

Tank shouldn't be that hard to clean out being plastic.  

At least it's just sludge and not rust flakes in there. And it's an easy job, I like eliminating the simple stuff first, hopefully that will help especially as it ran fine for about an hour's non stop use then started playing up again.

[Dan.gerous 2,696]

Have just ordered a nice fuel filter, hopefully it won't take long to arrive.

 

[Stormin 9,981]

16 minutes ago, Dan.gerous said:

 hopefully that will help especially as it ran fine for about an hour's non stop use then started playing up again.

 

Moving over rough ground will have disturbed things.

[Dan.gerous 2,696]

1 minute ago, Stormin said:

 

Moving over rough ground will have disturbed things.

Yeah, I took it on a run around the farm and it's pretty rough now the tractor ruts have dried out! Anything dodgy or about to break will do it in those conditions!

 

I didn't realise until getting the second C125 how crap the first one is. Everything is stiff or rattling whereas the other one steers like a dream and not much rattles other than all the pulleys with shot bearings.

 

Will let you know how I get on with the tank later today.

[Stormin 9,981]

  BTW. Is the fuel cap still one with the gauge on? If so make sure the float guide is clean. My Black Horse's was a bit rusty and some of the minute rust particles found they're way to the carb.

[Dan.gerous 2,696]

3 minutes ago, Stormin said:

  BTW. Is the fuel cap still one with the gauge on? If so make sure the float guide is clean. My Black Horse's was a bit rusty and some of the minute rust particles found they're way to the carb.

No it's just a simple cap so in

theory there shouldn't be much in there to rust....

[Dan.gerous 2,696]

Just drained the fuel tank, seems to be a lot of red paint in there!

 

About to give it a wash out.

 

Then I guess it's back to cleaning the carb again 😐

[Dan.gerous 2,696]

Finally got back to this machine, have been spending more time adjusting the rotovator machine.

 

So got the cover off for the points and notice the spark is often non existant, then very erratic, then its fine for a bit etc

 

Would this be the coil/condenser playing up? next thing is to borrow the one off the other machine - but I am wary of messing with that one as it runs perfectly!

 

 

[gwest_ca-(File Mod) 11,032]

Try one at a time in case one of them fixes it. They way you will identify the problem.

Make sure the body of the condenser is grounded when mounted to the (-) side of the coil. Have seen fresh paint act as an insulator preventing the condenser from working.

 

Garry

[953 nut 55,066]

With a battery ignition system, the ignition points are closed the majority of the time. With the points closed and the ignition switch ON the primary windings of the ignition coil have current flowing through them and are developing a magnetic field in the iron core of the ignition coil. The moment the ignition points open the magnetic field collapses and induces a momentary high voltage pulse in the secondary windings of the coil which goes through the spark plug wire and arcs across the gap of the spark plug. If this occurs in the presence of a compressed fuel/air mixture of the proper ratio an explosion will occur within the cylinder. If this explosion occurs at the proper time in the engine’s cycle there will be pressure applied to the piston forcing it downward on the power stroke. The ignition points will continue to open further after this has occurred. How far they open is immaterial, their work has been done for that cycle of engine operation. What is important is when they open relative to the position of the piston on its compression/power revolution. If it occurs too soon there will be backfiring, too late and there will be a reduction of power. In the case of our Kohler engines the sweet spot is twenty degrees Before Top Dead Center, that is what the “SP” mark on the flywheel is set to). At the moment the points open the condenser quenches the arc across the points extending their life, the rest of the time it just sits there. 

[Dan.gerous 2,696]

Today I swapped the condenser, coil and points of my other C125 onto the one that was backfiring, it now runs like a dream.

 

That's quite handy as the other one has blown it's head gasket!

[Dan.gerous 2,696]

Also added this to keep the fuel system primed, no more long cranking in the mornings.

[Stormin 9,981]

That's the same primer bulb I have on my C-125 and the Black Horse. Big aid to starting when been idle. I must get one for the C-81 one day.

[Dan.gerous 2,696]

7 hours ago, Stormin said:

That's the same primer bulb I have on my C-125 and the Black Horse. Big aid to starting when been idle. I must get one for the C-81 one day.

Such a simple but effective modification, I need to get another one for the other C125.