1986 johnson 20hp tiller electrix start

[Rugglesworth]

Hi all my son and I picked up this old johnson 20hp tiller from a family friend who passed away. It's been sitting outside for 10 years but still clean inside and not seized. What spec battery do I need for this? I want to clean the carb and fire it up. No water in the cylinders. I feel like it will fire up. Battery specs would be appreciated. Cheers

 

[saltchuckmatt]

Standard lead acid battery, group 24 should be fine or step up to a G 27.

Don't start it with an old impeller, it may fail and get rubber bits up in the cooling passages.

 

[airshot]

For example hat small of motor, even a lawn mower size battery will work unless your using that battery for other things.. I would not waste my time just doing a carb clean, they rarely work well especially on a motor that has sat for 10 years. Get a factory rebuild kit with new gaskets, needle and seat plus the instructions for setting up that carb so it will work correctly. The extra bucks will relieve the headache of having to do it over....

 

[Rugglesworth]

Thank you both for the information and yes it makes sense to get a rebuild kit for the carb and a new impeller.

 

[Rugglesworth]

So we haven't started the project yet as my sons football season is still going for another couple of weeks. I did some digging on the battery requirements and found this:
Johnson 2 stroke 9.9-50 Carbureted 360 CCA (465 MCA), 50 amp-hr minimum. Is this really needed? I am then assuming a lawnmower battery would not be sufficient to start this thing? I'd rather not spend $150CAD for a battery on a motor that is possibly cooked. One other question. Is it possible to convert this motor to pull start?

 

[saltchuckmatt]

You would need a used similar motor. Flywheel, recoil system, cowling ...

Even though someone on here said a lawnmower battery will work, at least a group 24 battery would be my smallest battery like I already said.

At this point you may want to back up and do a compression check before moving on and spending money.

 

[racerone]

My garden tractor is 26 HP and uses a typical garden tractor battery.

 

[Rugglesworth]

You would need a used similar motor. Flywheel, recoil system, cowling ...

Even though someone on here said a lawnmower battery will work, at least a group 24 battery would be my smallest battery like I already said.

At this point you may want to back up and do a compression check before moving on and spending money.

How would I do a compression test without a way to turn the motor over? Or would spinning the flywheel with an air rachet do the job?

 

[racerone]

I am quite sure there is a provision on the flywheel to pull it over with a rope !-----Do not use power tools on the nut !

 

[Rugglesworth]

Yeah I thought that might be an issue so I researched it more and came to the same conclusion. The motor doesn't have a pull cord so I'll have to fashion one up or try to find one. In the meantime I've ordered a leak down tester to see what that shows me.

 

[racerone]

I use my experience and thumb on the sparkplug hole.----Rotate flywheel by hand against compression and release thumb.----Judge by the " pop " I hear after a count to 2.----Also do it with pulling piston down to judge vacuum the same way.-----I did not learn this technique overnight either.

 

[saltchuckmatt]

I suggest borrowing a bigger battery and test....what do you have to loose?

How are your battery cables?
Have you tested volts at the solenoid and at the starter during start up?

OMC guidelines, as you stated, doesn't meet spec.

Just saying.

 

[airshot]

My garden tractor is 26 HP and uses a typical garden tractor battery.

Same here, twin cylinder lawn mower with a tiny little 6 ahm battery that is half the size of an ATV battery, been starting my mower for three years !!
When I had my Johnny 9.9 electric start I used an ATV battery for years to start it.

 

[Willyclay]

May be some help at the link below. Good luck!

Awakening a sleeping outboard; by BoatBuoy

I see a lot of posts from folks who have a motor that has been in storage, belonged to their dad or granddad, or for another reason. I recently went through most of these steps myself in preparing a motor which hadnt been used for 15 years. Following is an attempt to provide a concise list of...

forums.iboats.com

 

[cyclops222]

Hard starting motor ? Means more than 1 or 2 seconds cold with choke use. I use a old size 24 car battery. Fantastic cranking speed....... Now just jumper from a car battery. good enough. You are sure the boat battery cables are perfect low resistance ?

 

[jitterbug127]

u-1 battery will turn thing over plenty easy. I’d use the one from my mower or car to do compression test before spending cash on a battery for a motor I can’t use. My lawn mower is 26 hp. Fires right up easy with u-1. My outboards are 15/25/35 hp all will start with a u-1 battery.

 

[Rugglesworth]

Update: so my son and I have been working on the motor periodically. I did a leak down test and it passed with flying colors dry which I was amazed at. So I got an old used 12v battery to test the starter. To my surprise it worked as well. So I tested the spark and both fired although one was weaker. I got some new plugs as again this thing was outside uncovered for over 10 years. Put them in and it kept backfiring out of the prop. It was like a weird bang. I swapped the coil wires as it sounded like the firing order was wrong and it fired right up!!! I shut it down immediately as I haven't done the impeller yet. I am sure it's toast. Water pump is next then we'll have to test it but it was idling beautifully. Unbelievable.

 

[saltchuckmatt]

Wires going to ignition coils are orange with strips, blue stripe top, green stripe bottom. Might not be visible.

Now pray that old impeller isn't stuck up inside your teeny weeny water orifices!

 

[Rugglesworth]

Wires going to ignition coils are orange with strips, blue stripe top, green stripe bottom. Might not be visible.

Now pray that old impeller isn't stuck up inside your teeny weeny water orifices!

They are the same color on this motor but I traced the wires from the CDI to the coils, top wire on CDI to the top coil etc. Looks like someone was messing with it previously. Yes I am hoping that the impeller isn't disintegrated into the cooling orifices. I will report back once the new impeller is installed.

 

[Rugglesworth]

ok so we got the water pumping through the motor now. She idles super smooth but has a hard time revving. Carb rebuild? I am surprised how well she idles cold.