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Author Topic: Jiffy 3 hp tecumseh tuning  (Read 44281 times)

Offline mikeypmcg

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Jiffy 3 hp tecumseh tuning
« on: Jan 08, 2009, 09:09 AM »
some useful info i found about tuning your jiffy, hope it helps someone.

picture of carb set-up





First change the spark plug and have fresh gas w/correct oil ratio.

The most common carb used on augers are the Walbro.
They all have a fuel pump which consists or a body and diaphragm. There’s a port goes from the carb through the gasket and into the crank. As the engine is turned over it sucks and blows though that port, in turn moves the diaphragm. That diaphragm can get stretched out or breakdown, in either case it can't pump the fuel like it should.
There’s also a gasket in the carb stack that has little flaps, those flaps allow gas movement in one direction. Those can go bad too.

Next is the fuel inlet valve, It opens and closes the flow of gas going into the carb determined by the fuel level.
It’s held in place and hinged on a fulcrum with an adjustable tang. That tang adjusts the fuel level in the carb.
With a float/bowl carb you adjust by the float drop but we're talking about a carb without a float & bowl right now.
In our case the tang should be level with the carb body.
If you look, the center of the pumps diaphragm will come in contact with the inlet needles tang. In both cases, float & bowl or bowless carb, The tip of the inlet needle can become damaged and either stick in place or become damaged enough to where gas will seep by when it should be closed.

So say your auger isn't running right and you take the carb off and clean it. You should buy a carb kit and replace the gaskets, diaphragm and inlet valve and seat too.


Not all Walbro carbs are the same. Some use both Low speed and High Speed mixture adjustment screw. Most times you can adjust the mixture to get the auger to run at its best but not if the diaphragm or valve/gaskets are bad.

Some and most new engines have internal jets. You'll have to take that carb apart to clean and replace the diaphragms and clean the jets. The jet is made of brass, its inside diaphragm is tiny so it doesn’t take much restriction to effect how the auger runs. Brass is also soft so don't enlarge the hole when you clean it.

Some augers with the fixed main jet will benefit from replacing that jet with a larger jet. I did just that with my Nils. Your auger might benefit from that too. Modern small engines have to conform to EPA standards. It’s impossible to get peak performance out an engine that has to meet those standards in cold weather conditions.
Normal operation was a good warm up till the auger would cut. Now you should warm any engine up before putting a load on it but the warm time up required for the Nils seemed extreme. Once warm though it cut like no other auger.
I went from a .37 to a .38 main jet. End result, no long warm up times and more power when under load. I'll get into that mod with pictures at a later date.

Back to the tune up.
This will be for the Walbro carbs with the High and Low Speed mixture. Your carb will have an L and k stamped into the carb body. There’s also an idle speed set screw.
Let the engine warm up. Start with the Low speed mixture. Turn it in (clockwise) till the engine starts to run high and or slow down. Now turn it out till the engine runs at its highest RPM. You can go in and out to get it at that point.
Once you get Low speed adjusted so the engine run at its highest/smoothest point you turn the screw out till it starts to just slow down. Why wouldn't you leave it where it runs at its highest point? Because it’s running lean there and will be hard to get started. Turning out will richen the mixture so you won't have to pull on the rope more then a couple times to start it.

Now you have to adjust the High Speed. This should be done under load/cutting ice. Adjust till you get to the point of max RPMs and then again turn the screw out till it you notice the engine slowing down. Do that and you won't be running lean; Running lean will burn an engine out. That’s especially important if you like drilling a series of holes one after another.

Basically there are 3 adjustments to a carb. Idle speed- is a simple stop screw on the external linkage to set idle speed.

Low Speed Adjustment- this will meter the gas/air mixture inside the carb.

High Speed- this will meter the gas/air mixture at high speeds.

Turning in - Clockwise = lean
Turning out - Counter Clockwise= Richen.

If the won't run without having to prime or without giving throttle you are too lean at Idle Speed. You want to richen that mixture.

At high speeds if the engine won't run without priming you'll need to richen that adjustment.

In an attempt to make small engines friendlier, we start seeing limiter caps on High and Low Speed adjustments or no adjustments at all and fixed jets are used.

If this is a problem that has just started then you should look into having the carb cleaned and rebuilt.

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Offline SilverSides

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Re: Jiffy 3 hp tecumseh tuning
« Reply #1 on: Jan 08, 2009, 11:11 AM »
Great Info!   I saw carb kits the other day on eBay for about $10.

Offline Mainedog

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Re: Jiffy 3 hp tecumseh tuning
« Reply #2 on: Jan 08, 2009, 11:27 AM »
Excellent post, Mikey.  Thanks. 
I hope whoever bought my 3hp Legend reads this!

Offline Downeaster

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Re: Jiffy 3 hp tecumseh tuning
« Reply #3 on: Jan 08, 2009, 11:41 AM »
I agree very nice post.  Now to get something on the problem with the governor not kicking in.
I am getting fed up and about to go electric.  These Jiffys are disgusting when they don't work
well.

Offline LeadRemovalguru

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Re: Jiffy 3 hp tecumseh tuning
« Reply #4 on: Jan 09, 2009, 07:59 PM »
nice post... :thumbsup:

Offline Quantoson

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Re: Jiffy 3 hp tecumseh tuning
« Reply #5 on: Jan 12, 2009, 04:25 PM »
I book marked this page. thanks!
wish you many hook-ups

Offline Webbicefisher

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Re: Jiffy 3 hp tecumseh tuning
« Reply #6 on: Jan 12, 2009, 07:19 PM »
Awesome thanks...my jiffy deff has carb issues


Offline natureboy79

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My name is Andy and i'm a fishaholic....

Offline windflag77

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Re: Jiffy 3 hp tecumseh tuning
« Reply #8 on: Jan 12, 2009, 07:54 PM »
i just bought a used jiffy, it idles fine but the first weekend out it would drill good for about 6 seconds then would start to stall out and if you just let it idle for 3-4 seconds you could start drilling again for another 6 seconds then the same thing would happen. if you try to stay in the throttle when it starts bogging down it will just die. I tried making a slight high speed adjustment leaning it out thinking it was getting too much gas. I took it to a local lake in the middle of the week and drilled 5 holes slick as can be. I thought i had to problem solved but last weekend i took it out on its second trip and it did the exact same thing as the first time. I am not sure what is wrong or where to begin tuning the carb. any suggestions are greatly appreciated.
FLAAAAG!!!!!!!!!!

Offline Bugman1964

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Re: Jiffy 3 hp tecumseh tuning
« Reply #9 on: Jan 12, 2009, 08:20 PM »
Try decorbing with seafoam. Get the auger warmed up best you can. Spray seafoam into the air intake, throttle to keep it running. Use about a quarter can. Give carb a good shot of seafoam, shut off, remove spark plug. Spray a lot of seafoam into the cylinder, replace plug and let auger sit over night if possible. Start auger run till it stops smoking, it will smoke a lot with the seafoam. Replace plug with new plug. Seafoam can be found in most autoparts stores. Use freshly mixed fuel. Decarbing is common with two cycle engines, especially outboards.

Offline ICEMAN-73

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Re: Jiffy 3 hp tecumseh tuning
« Reply #10 on: Jan 12, 2009, 08:50 PM »
Good info! my Jiffy 30 started running like crap this year so after my second trip out i brought it into my garage and sprayed the carb down good with carb cleaner, filled it with fresh gas, set the carb back to correct settings then fine tuned it from their. Runs like a camp again! Thanks mikeypmcg
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Offline windflag77

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Re: Jiffy 3 hp tecumseh tuning
« Reply #11 on: Jan 15, 2009, 04:41 PM »
Hey guys, worked on the auger last night. I adjusted the high and low speed adjustments and used sea foam. I have her idling and running good, but that wasn't the problem if you remember my post 3 days ago. I actually counted the seconds that it would run good on full throttle. It idles good, has really good throttle response and sounds excellent for 13 seconds then it starts pulsating and if you let it idle for a few seconds you can open her up for another 13 seconds and it does the same thing. If you try to stay in the throttle while it is bogging down it will die. one pull of the cord and it idles fine. any ideas what could be causing this and how to correct it. like i sd it runs strong and idles good other than this, but it has me stumped. Thanks for the help
FLAAAAG!!!!!!!!!!

Offline EL CAPITAN

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Re: Jiffy 3 hp tecumseh tuning
« Reply #12 on: Jan 17, 2009, 07:42 AM »
thanks for the valuable info!!!
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Offline Huntermike

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Re: Jiffy 3 hp tecumseh tuning
« Reply #13 on: Jan 17, 2009, 09:54 AM »
Hey guys, worked on the auger last night. I adjusted the high and low speed adjustments and used sea foam. I have her idling and running good, but that wasn't the problem if you remember my post 3 days ago. I actually counted the seconds that it would run good on full throttle. It idles good, has really good throttle response and sounds excellent for 13 seconds then it starts pulsating and if you let it idle for a few seconds you can open her up for another 13 seconds and it does the same thing. If you try to stay in the throttle while it is bogging down it will die. one pull of the cord and it idles fine. any ideas what could be causing this and how to correct it. like i sd it runs strong and idles good other than this, but it has me stumped. Thanks for the help
i had the same problem and it was the high speed jet wasnt getting enought fuel
turn the jet counter clockwise.
next time your out do it when you use it    good luck

Offline windflag77

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Re: Jiffy 3 hp tecumseh tuning
« Reply #14 on: Jan 17, 2009, 11:41 AM »
this has all been helpful info i appreciate all of it. keep it coming if anyone else has any suggestions
FLAAAAG!!!!!!!!!!

Offline mainedukblaster

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Re: Jiffy 3 hp tecumseh tuning
« Reply #15 on: Jan 17, 2009, 12:26 PM »
this has all been helpful info i appreciate all of it. keep it coming if anyone else has any suggestions
problem sounds like your air fuel mixture screw might be a little too much closed.. needs a little more air, also your high speed screw might be open a little too much, you are almost there if it runs but then bogs, sounds like you are just getting alittle too much fuel in the engine and it gets to the point where it can't have a good combustion cycle..  ,  also make sure you are good and warmed up too. 
but like I said you are almost there.. a few Minor tweaks and you will be gold.  Small adjustments needed now..

Offline Shepabs

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Re: Jiffy 3 hp tecumseh tuning
« Reply #16 on: Jan 19, 2011, 07:30 AM »
Just Joined Iceshanty and was cruising the old posts and came across this one.  This is exactly what I needed.  My Older model Jiffy, circa early 80's has bad carb problems.  My fix was to buy a new Nils Master 8" a few years ago.  I haven't ice fished since I bought it because of travelling for work.
My old jiffy is sitting in the attic of the barn just hoping I'll take it out and fix it some day, sell it or give it to one of my boys.
This post is tops!!  Thanks 



Offline esox_xtm

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Re: Jiffy 3 hp tecumseh tuning
« Reply #17 on: Jan 19, 2011, 07:53 AM »
This info is not just for Jiffys as Strikemaster and Eskimo also use Tecumseh engines. There's not a lot that you can adjust, but this was great info on what you can.

I'll not only second the use of Seafoam, but endorse it's use in every can or tank of two cycle gas I mix. I got on to it taking care of my outboards and I never have issues. Two cycles can carbon up and effect performance; dosing with Seafoam as described can clean that right out. Furthermore, regular use and using a quality oil in your mix goes a long way toward keeping the carbon deposits down in addition to keeping fuel systems clean and acting as a fuel stabilizer.

Thanks!

/m
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Offline Fishurman63

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Re: Jiffy 3 hp tecumseh tuning
« Reply #18 on: Jan 19, 2011, 08:04 AM »
i just bought a used jiffy, it idles fine but the first weekend out it would drill good for about 6 seconds then would start to stall out and if you just let it idle for 3-4 seconds you could start drilling again for another 6 seconds then the same thing would happen. if you try to stay in the throttle when it starts bogging down it will just die. I tried making a slight high speed adjustment leaning it out thinking it was getting too much gas. I took it to a local lake in the middle of the week and drilled 5 holes slick as can be. I thought i had to problem solved but last weekend i took it out on its second trip and it did the exact same thing as the first time. I am not sure what is wrong or where to begin tuning the carb. any suggestions are greatly appreciated.
  When it starts to stall out reach down and hit the primer bulb once and see what is does that maybe telling you the diaphramn in the pump is getting weak.

Offline tcfish

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Re: Jiffy 3 hp tecumseh tuning
« Reply #19 on: Jan 19, 2011, 09:39 AM »
  When it starts to stall out reach down and hit the primer bulb once and see what is does that maybe telling you the diaphramn in the pump is getting weak.

       MIne still does this and i just had it rebuilt last year????????
i ain't scared

Offline Klimshack

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Re: Jiffy 3 hp tecumseh tuning
« Reply #20 on: Jan 19, 2011, 09:49 AM »
Man, what a great post....wish I had seen it yesterday.  I just dropped my jiffy 30 off this morning to the repair shop.  Probably could have saved myself $60-70 in labor.

Thanks for the good info! Next time.

Offline McIce

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Re: Jiffy 3 hp tecumseh tuning
« Reply #21 on: Jan 19, 2011, 10:30 AM »
Very Helpful!
My Auger ran perfect when I test ran it prior to the Sabattus Derby. On Derby morning, it fired right up and ran until it was under a load, the it would die right out like it was starving for fuel when it tried to run on the governor....., my friend the mechanic to me that because it was SOOOO cold on Saturday, the air/fuel mix was leaned right out. He said I needed to "fatten up" the mixture when it is that cold.
Now I know how....., thanks!
I wasn't running the net!                  :icefish:

Offline mikeypmcg

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Re: Jiffy 3 hp tecumseh tuning
« Reply #22 on: Jan 19, 2011, 11:13 AM »
it is true that cold air will cause a lean mixture, adjusting the jets isnt always the fix for that.  The best thing to do is let it warm up completely (may take over a minute!) before putting it under load.  a warmed carb will atomize the air fuel mix correctly.

Offline mikeypmcg

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Re: Jiffy 3 hp tecumseh tuning
« Reply #23 on: Jan 19, 2011, 11:15 AM »
       MIne still does this and i just had it rebuilt last year????????

thank the government for putting ethanol in the gas.

Offline mikeypmcg

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Re: Jiffy 3 hp tecumseh tuning
« Reply #24 on: Jan 26, 2012, 11:55 AM »
bumping this to the top for others that may be running into problems now.

Offline Relheok

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Re: Jiffy 3 hp tecumseh tuning
« Reply #25 on: Jan 29, 2012, 03:37 PM »
Thanks guys, going to give her one more shot in the morning before I just drop her down a big hole to the bottom!

Offline Hammer

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Re: Jiffy 3 hp tecumseh tuning
« Reply #26 on: Mar 31, 2012, 11:15 PM »
i have a 3 hp jiffy i have heard that there is a replacement/updated carb available?  has anyone heard about it?
i have been trying to tune my but have had little success,  new carb kit needle and seat diaphram,  new fuel cap, carb has been cleaned.

i have read a few threads on how to adjust the low and high screws,  my carb only seems to have the high screw,  were the low screw would be there is a frost plug.

the low end is were i am having trouble.  starting and idleing.   it runs good when she is pinned.

any one came across this carb setup before or is this a factory defect,

any feedback would be appreciated.

Offline mainedukblaster

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Re: Jiffy 3 hp tecumseh tuning
« Reply #27 on: Apr 01, 2012, 09:28 PM »
hammer sometimes there is a red cap over the screws.. you have to pop those off to get to the screws for the high and low jet... if I find the pics I'll post them



Offline mainedukblaster

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Re: Jiffy 3 hp tecumseh tuning
« Reply #28 on: Apr 01, 2012, 09:30 PM »


Left screw is low speed
Right screw is high speed

Lose the red caps if you have not done so already.

1. Gently close the jets.

  Right from Jiffy

2. Open Low speed 1 1/8 turns
3. Open High speed 1 1/2 turns

Mine ran best at 3/4 turn and 1 1/4 turn

4. Adjust the low speed until the engine idles smoothly.

5. Let cool off. while cooling, adjust High speed jet

6. Once cold fire it up and open it right up from an idle.

7. Keep adjusting High speed until you get a smooth transition.

shut off and allow to cool.

Repeat #7 until you get a smooth transition

hope this helps,

Ben

(should not take more than 10 minutes tops)


Offline Hammer

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Re: Jiffy 3 hp tecumseh tuning
« Reply #29 on: Apr 03, 2012, 05:30 PM »
thanks for posting the picture, my carb currently doesnt have the plastic caps on the screws.  were the low screw should be located is a frost plug.  any thoughts on why it is plugged off.

 



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