My S/G is only two years old so it should be good to go.

I like to recommend putting the ignition on a separate toggle switch. that way you can get the engine spinning then hit the ignition switch, its allot easier on the starter

Summary
 

This thread has run on much longer than I ever expected. Thank you to all that contributed, especially dvogtvpe. Here is what we have so far. Correct me if I am wrong and I will edit.

1. For safety reasons, govern the engine to 3,800 rpm. Maximum torque will be made between 3,000 and 3,400, so additional rpm are an unnecessary risk with a stock flywheel.

2. For a stock 12 hp. engine, it is best to run with a 16 to 17 tooth second gear. This can be accomplished with a 20% under drive. This is the biggest thing to make you competitive starting out. Running in a stock first gear is too low and second gear is too high if you have the standard 13/19 tooth gears.

3. For a 12 hp. engine, run a #26 carb. You get more torque.

4. For more hp. for a 12 hp. engine, bolt on an LP head. It is the easiest way to get an extra 2 hp. without rebuilding the engine. If you can't find an LP head, use a second generation head and have it milled 0.05.


Next year the engine will be rebuilt with a Kerber #3 cam, undercut valves, and a balanced steel crank.

then you probably want to budget in a good carb if you're going with the rest

What do you mean by a good carb? I have a new #26.

New pull results. I pulled in three classes.
Garden modified 10 to 14 hp., 23" tires, Finished Second
Heavy modified uncut, 16 hp., 26" tires, Finished Second
and Light modified uncut, 12 hp., 26" tires, Finished First.

Seems I still don't have enough power to get past the 14 hp. tractors. Doing good to finish second in the 16 hp. class though.
Maybe next year.

Just for those that are green with all Gens of Cub Cadet. 2nd Gen would be your 12hp Kohler' s or 14hp Kohler? I have been following this thread very close and I have learned a lot is good information. Thank you

after you put a cam in it with good valve work you will find a new carb won't preform like a "good carb"

2nd gen is what people call the 10 hp head with a dump area between the valves and cylinder, the so called LP head was really the first 10 hp head

Second generation still has the heart shaped area around the valves, but has the depression below the valves like the later heads. They are much cheaper than the LP head and will give you higher compression than later heads, but not as much as a LP head, which has no depression below the valves.

Don,

Is this something that you do on all tractors or just on your pulling tractors?

Thanks

just engines where we advance the timing and put enough compression in to cause starting problems

I can see that. I am having more trouble starting mine now. Plan to add the switch next weekend.

Removing Choke
 

When removing the choke, what do you use to fill the holes in the carburetor? I was thinking JB Weld or silicone. Thanks

silicone works good

Added the switch and it works well. Went to the pull tonight and noticed my engine was detonating when pulling hard. I adjusted the carburetor by 1/4 turn to make it richer. It helped but didn't get rid of the pinging. Plan to back off the timing by 2 degrees and use premium gas. Am I heading in the right direction?

where are you at for timing? LP head?

I am at 20. Just got through timing at 18 and 16. 16 is definitely too low. Think I'll go back to 20 and just use better gas. At 20 it sounds like pots clanging together at the end of the pull. It wasn't as bad when I increased the fuel mixture though.

Put it back to 20. Starts easily with no hint of firing before TDC. It has to be the fuel. Been using some 87 non alcohol fuel with Seafoam added.

are you gapping the points or did you degree out the flywheel? you should be able to run around 24 degrees on midgrade gas. count how many turns out your main jet is at

Gapping the points. Get back to you on the main jet.

Main jet is out 1- 3/4 turns.

You should be able to run 24° timing without issue. Time your engine using the static timing method gapping the points does not set timing.

Thanks. I'll give that a shot this weekend.

OK. I found the timing marks. Set it so it the points just open right on the S. Went back to the white dot I have been using for setting the timing and it was gapped at 0.02. Seems someone marked the spot where the points have the widest gap. Gapped it at 0.022 and checked the static timing. It looks right. Cranked it and it was a bit hard to start as expected because of the advance. So, timing is not the issue.

Thinking back, I tweaked the carburetor the day of the pull. Backed off the richness until the rpms went up. I was running the carburetor too lean. I have readjusted it by enriching it until it runs rough, backing off until the rpms start going up, then enriching it a quarter turn. Does that sound about right?

that sounds like your problem. I usually let them pop once or twice during a run . it would happen early in the run but as load comes on it clears up and has nice torque

So, you are saying it is OK to have the occasional miss from being over rich?

yes, early in the run its ok when the motor is free reving

Last pull of the season, for me anyway. I came in 3rd, 2nd, and 1st in my 3 pulls. This pull is usually a trophy pull, but with all the controversy over our insurance, it was overlooked. Maybe next year.

Tomorrow I will convert the tractor back to a dirt mover. The spare engine will be rebuilt over the winter for next pulling season. The plan is to swap engines and use one for pulling and one for moving dirt during the off season. It would be better to just have two tractors, but this is the next best thing.

Next season I should be getting about 18 hp. from the new engine. Should be pulling first place every time :ThumbsUp:. Thanks guys for all the help so far.

just remember the more HP without drive line mods the risk of breakage goes up

Last year I had a 3 puck clutch, stronger drive shaft, and the thick casting carrier and fine splined axles installed. Hopefully, that will hold me through next year. After that, I will buy a complete transaxle from Midwest Super Cubs.

Just a note on the Carlisle AT101s. They have been performing very well for me on loose and hard tracks. I mounted them on 10 inch rims, and run them with 10 lbs. pressure.

did you put a steel pinion bearing holder in? try dropping your tire psi when the track is loose, 7 should be good

No. Do I need to?

The AT101s are pretty thin. Have you tried them at 7 psi.?

yes you do.
I've never run those tires. but under pulling theory hard track = hard tire. soft track = soft tire . on a soft track you don't want the point of the tire digging in. you want to spread the tire out more for a larger footprint. hard track you want allot of point , so you raise the pressure to get allot of pressure on the center of the tire

Surprisingly, it doesn't look like the venturi was bored out at all. Will this carburetor be good enough, or do I need to send it somewhere else for more work? I have no idea what was done on the inside other than a basic rebuild.

Use it as is the idle circuit has been reworked as well as some other things. Boring out the venturi might only hurt torque on the big end of the track.

OK, thanks. Did you ever order that governed carb from Lakota?

I have it but have not used it yet as, I have not had time to take it to the dyno for tuning yet.

Do you guys use a PTO dyno? Just wondering because a lot of you guys that have a lot of pulling experience, that I appreciate, talk about dyno runs i was just wondering how you ran those runs. Thank you.

Most have a test stand that the engine bolts to and is hooked up to either the PTO end of the crankshaft or the flywheel. Just depends on the set up.

I appreciate it, thats good information. thank you

we dyno off the PTO end. I think if we ever did it again we would drive off the flywheel end. I think its hard on cranks when you have a heavy flywheel