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.