Convert electric start to pull start... Will my existing flywheel work? Info and pix!

I am a semi-novice at small engine stuff; I've done some repairs before and had varying degrees of success. IT guy by trade. Love the feeling from fixing myself and learning. Willing to gamble.

Lawnmower is an inherited Snapper NTX that uses a B&S 121S07-2116-F1

This is an electric start only mower.
It has always started fine when it turns over; however, the starter has had increasing difficultly turning the engine over the last 10 mows and now it will not turn over at all.
I pulled off the top plastic and can turn the flywheel manually (spark plug disconnected) easily.
I tried a different battery.
I jumped the starter directly to a battery.
Still not enough ooomph in the starter to turn it over... i can tell it is trying.

Since these starters are North of $100 and, reading around the web, are prone to failure I was thinking of converting it to pull start unless all I would need to replace are the starter gears.

Questions:

What are the chances I would only need the gears labeled 937 for this starter? How would I test that to determine if the gears are the problem or something in the starter itself?



If I went with the pull start conversion would my current flywheel work with just replacing the round plastic cap/top with the rewind starter?

I currently have parts ( in diagram )
304A
73
What I'm wonder is can I just replace 73 with part 608. Will it work with the four aluminum posts on my flywheel (see next section)



I have Flywheel 23... A better stock picture is below:


Picture of lawnmower:


Thanks in advance!

Jeff from Little Rock, AR

Assuming your battery is good ( 12 + volts) and the rest of the starting components are good, ( starter solenoid, keyswitch, battery cables, wiring harness, safety switches ) then I would FIRST ... adjust the valves (see manual in link) .. Pg.21

https://drive.google.com/file/d/0B6NaqjIxWV1ybEN0LWo3azl6OUU/view

https://www.youtube.com/watch?v=H8C25hFv1mU

only PULL-start conversion I have seen is this ........

But it's an old "rope-wind" pulley adapted to the engine, BEFORE you invest any further time or money I would do the valves adjust, these engines were designed for the electric start for EASE of starting and are quite dependable in that aspect.

AS you have already downloaded the parts book.
Check to see if there are two different crankshafts listed.
Briggs use a longer crank on the pull start models.
If there are two listed then the starter motor would be a cheaper fix.
Also check the starter mechanism
If it uses a cup then you might just get away with a new cowel, starter cup & pull start
If you have access to threading taps then you can get a plain pulley, tap it to fit the crankshaft and use a rope.

Did a little more searching, and I really did NOT dig deep, but I think you would probably have to change the flywheel -$133.xx add the fan -$16.90, the cup - $8.70 the recoil assy., - $45.24 and the new housing - $ ??.?? and maybe a few other items, this is the ONLY dealer I checked so you might find prices lower elsewhere, AND I'm NOT positive this is all the CORRECT parts ! I think you might want to consider repowering with a new "EL-cheapo type engine" or even another used mower, the price of the needed parts for the conversion to recoil start is crazy in my book . you can do further research if YOU care to, you can find the flywheel in the attached diagrams along with the engine model I used to find the flywheel ( 111P02-01202-F1 ) should be the same type. best of luck in your quest .

...

......

I'm wondering if he adjusted the valves.

hrdman2luv said:

I'm wondering if he adjusted the valves.

Click to expand...

Me too !!

Thanks for the responses.
I thought I had the site configured to notify me when there were responses and no one had responded yet. That’s my fault. I was surprised to see the activity here. Thanks for the time you have spent. I will adjust the valves and report back ASAP!

Thanks for the up-date !

Success!

I tried to start it once more and got little to no action from the starter... It's been a while since I tried and it's been cold and I mistakenly left the battery out in the cold for a while...
BTW someone had replaced the original with a larger AGM alarm-system sized battery bolted near where the original should be.

Just to be sure I hooked up a freshly float charged similar AGM and it was a *little* better but still got the same partial turn then hanging.

I watched the videos and links y'all sent and found a gap tool that probably got handed down from my grandfather.
According to the B&S check chart (i still can't post links yet sorry) the gap clearance was supposed to be .004-.006 on the intake and exhaust rockers.

One of them was .010 and the other .008... not sure how far off it would theoretically need to be to hang up but I reset them to .004 hooked up the same AGM and it started right up..
It actually scared me how quickly the starter turned the engine as it has never worked that well since I owned it.
Stopped and started it 4-5 more times with no issues.

I'll recharge the smaller AGM or try to find something better than the big ole brick AGM it currently uses.
Anyone used lithium ion 8650s or caps for a battery starter? I suppose that is a different topic.

I can't wait to tell the wife who has obviously lost all faith and just nods and changes the subject each time i bring up working on it.
To be fair it has been out of commission for a quite some time...

In any case THANK YOU for helping and I'll try to pay it forward..

-Jeff

Glad you got things in order Jeff, amazing when you adjust the valves to specs. ehhh ?? ..:thumbsup: