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Kohler K61 air gap question

hbwb

Registered
First time posting here.

Recently bought a troy bilt horse tiller off craig's list. Checking the serial number shows it was made in 1980. Engine is a Kohler K61 from what I could dig up. After cleaning the carb I discovered there was no spark. I am not unfamiliar with magneto ignitions but have never dealt with one that has no setting for the air gap between the rotor and the magneto/coil setup.

I have looked all over the net and could not find anything about what they gap was setup at the factory. Since this is a magneto under the rotor with points and condenser the gap cannot be adjusted. Or at least without some modifications. Most air gap settings fall around the 0.010 inch range with Kohler's generally around the 0.008 - 0.012 range.
http://outdoorpowerinfo.com/engine_specs/kohler_flywheel_air_gaps.asp
If you notice at the link there is no setting for some like the K161 because you cannot adjust those.

I have checked mine and it is around 0.017 - 0.018 which seems wide to me. I have looked many places but could not find what the original gap distance was. I was thinking maybe a previous owner wore down the magneto or flywheel by aggressive sanding which increased the clearance beyond a working setting. Anyone have any idea what the gap is supposed to be?

Btw great site and I look forward to reading over some of the stuff on here.
 

hbwb

Registered
Just as I suspected. Thanks GA.

Ok so is there a simple way to close the gap with the existing setup without buying another magneto? I noticed the assembly which includes the points rides on the shaft pretty tight so there is no wiggle room. Thoughts of mine included grinding out the pins of the iron piece of the magneto and slotting the holes and installing bolts. I also thought of maybe enlarging the hole a touch that fits on the shaft for a bit of room for movement and my latest idea was to add a little solder to the iron portion of the mag to close the gap a smidgen.

Do any of these sound workable? I think I like the last one best and I do not see how I could damage that sandwich of iron plates. As of now it is no good to me anyway so if the new condenser does not help I will do something. It is supposed to arrive monday. I had previously bought one from napa but it would not mount under the flywheel and while trying to relocate the mounting I put a dent in it. I did find what I needed on ebay after buying elsewhere. Why does it always seem work out that way?
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
that sandwich of iron plates is insulated, a very thin sprayed on insulation. i would not heat it! at least it is in transformers, research core steel, or E,I steel for the smaller units. on larger units it is also stacked in a certain way so everything ties together.
 

hbwb

Registered
That is why I am here to find out what might be workable and what is a stupid idea.

Anyone have any suggestions that might work? Anyone know how to check what part is out of thickness or what thickness the magnets are supposed to be?
In other words if the current setup is not right can I possibly check to find out why it is not? Buying another magneto when I need to replace the magnets instead would suck.

I am trying to fix this with as little purchasing as is needed. I only paid $100 for the tiller so I am not hurt even if I have to install another engine on it but I want to run the original Kohler engine is at all possible. I can get a 6.5 HP engine from Harbor Freight for about $100 but that would be a last resort. I just think old iron should stay old all the way if possible.
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
is your setup similar to a briggs? i think it is, if so the very first two things i would check is flywheel key sheered or partially sheered and the condenser.
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
hdwb, i watched the video you linked and i have had 3 or 4 of that style engine over the years but they all had a 12v coil so it sounds like you have something different. if your points are in the same location as the video check the wire that connects the points to your coil/ mag what ever you have, if it is grounded anywhere in between the points and its destination it will kill spark.
 

hbwb

Registered
Tracy that video was for Wrightlife51 who asked about setting the points on another machine.

As I looked at more videos to try and find my machine I seem to have been mistaken and it appears I have a Tecumseh HH60 instead. Looking up the serial number stamped in the machine I find the machine was manufactured in Sept 1980 but Troy-Bilt used 3 different engines at that time. The B&S, the Koh K61 and the Tec HH60. The breather on mine looked like the ones on the Tecumseh videos which made me go have another look at the flywheel cover. The guy had painted over it but I found a number stamped in it that begins with HH60.

Oh well I guess I will do some digging on that engine now.
Anyway I can get an edit on the title of this thread or should I just start another one?

Btw thanks for your help.
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
tecumseh a whole different animal! i have the same tiller. special flywheel to set the air gap, coil mounted under flywheel! IIRC you need what they called a setup flywheel, it had spokes or something close where you can set the air gap with it installed and work thru it.
 

Ogrebeast64

Registered
Regarding Tecumseh, the magneto under the flywheel is a prefixed gap. The only adjustments that I know of to be made is rotating the mag to properly set the ignition timing. I would suspect either a bad set of points, condenser, plug, or a short in the kill switch system.
 

hbwb

Registered
Well I have read you need a special flywheel to set the air gap. I have also read they are fixed and are not adjustable. I looked in the service manual of the Tec L-head but could not find any mention of a way to adjust these.

I know you can rotate the magneto to alter timing but there does not seem to be a way to move it closer to the flywheel magnets. If there were I believe I could gap them without a special flywheel through trial and error.

For those familiar with this engine does a gap of 0.0180 seem too wide?
 

gdstew

Registered
WHOA, STOP, HALT


1st --What engine do you have, a Kohler K161, or a Tecumseh HH60????

If you don't know, how about a picture??? There are numerous ways to ID by looking. Look on the bottom of the carb, Tecumseh usually has their name on the bowl. Is the air filter a paper coned shaped (Tec) , or round like a donut (Koh)? There is a governor shaft coming out of the block, Tec is vertical out of the crankcase, Koh is horizontal.

If it is a Tecumseh, easy. If Kohler then we still need to ID which ignition system it is. Lets get this right to start with, OK???

Welcome new guy! We all started out this way!
 

hbwb

Registered
I corrected it in post 10. It is a Tecumseh HH60. Maybe I should delete this thread and start another one. I did not see a delete option so am not sure that is possible though.

I'll try to get a couple pics up a bit later so all can see exactly what ignition is on there.

I have another question as well. Just ran a static compression check with the pull cord. It topped out at 70 psi after a few pulls. Is that close to normal? That seems about right for a valves in the block engine but I realize all engines are different.
 

gdstew

Registered
I was a Tecumseh Service Distributor for many years, we serviced the Tecumseh dealerships. I never saw a special flywheel for Tecumseh, although somebody could have made one for their own use. People would brings those mag assys in to be tested all the time. Since they weren't marked before removing, we told the customers to just put them back on using the scratches the bolts made. Timing etc, didn't seem to make any difference as long as they were close. Set the points .020" and clean them real good afterward. I agree with post 13. The Tecumseh ignition system was very reliable.
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
I never saw a special flywheel for Tecumseh, although somebody could have made one for their own use.
this could be very well the case, that was 30+ years ago and in trade school. could have been a training tool or a one off that was made for that purpose. i have watched a few videos since your post and really there is no need to remove the assy, the coil can be removed along with the condensor and points without removing the asssy...
 

gdstew

Registered
"there is no need to remove the assy, the coil can be removed along with the condensor and points without removing the asssy..."

Try telling that to the public!!!

Another one----Customers would chisel off the rivets holding the ID plate on so they could bring me the info on the plate. "It took me 1/2 hour to get that plate off." I would just write the info on a piece of paper!
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
Try telling that to the public!!!

Another one----Customers would chisel off the rivets holding the ID plate on so they could bring me the info on the plate. "It took me 1/2 hour to get that plate off." I would just write the info on a piece of paper!
yep, I know. my nieces husband has a car next door, its been there for over a year. today i see my brother inlaw working on it as i was heading to town so i stopped to see if he needed anything from town while i was out. the very first thing i notice right off the bat, hey dave, somebody put the lug nuts on backwards. there are people out there that should never touch a wrench.:rolleyes:
 
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