John Deere D120 21hp Briggs OHV very hard cranking, breaking metal pinion starter gears.

[Scrubcadet10]

OEM cam is available at parts tree

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[cyberslick18]

As a tool and die maker I could machine something to mount to the flywheel stud without tightening the existing bolt, and could create a simple clutch / safer mechanism to separate the drill from the flywheel once fired up, but I try not to spend all my free time machining if I can help it. Ive come up with some stupidly elaborate solutions to very simple problems.

I'm not going to lie, I'm very tempted to try and aftermarket cam at almost a quarter of the price of that OEM one. There are a few on amazon with okay reviews.

 

[Scrubcadet10]

reading through reviews on different CCP Cams, of those that fail it appears most failures of those happen within a few minutes, to hours of run time.
And the OEM cam lasted 400 hours...depending on how much you mow, that could be over 12 years.

 

[StarTech]

Well of the 5 after market camshafts that I brought off Amazon myself two had to the journals worked down by .001" just to fit in the engines camshaft bearings. The other have poorly finish camshaft lobes. And neither of the five oil pump shafts will fit. Plus on the last three the ACR was quite loose. On top of that I would have return the last three the company selling closed up shop soon after I got the camshaft in stock. No way to return so I am stuck with those garbage camshafts.

So personally I am not buying any more after market camshafts. Not worth it to save just $25 over my Briggs distributor price of $58.96. Once Brigg has them back in stock I'll at 5 of them for stock plus whatever I for repairs.

As for how OEM last it is the luck of the draw there too as I had one customer broken one last Summer and then again this Spring and he cuts only about 2.5 acres weekly. Then others have yet to break one like me that cuts up to 6 acres bi-monthly. I still on the first camshaft and the mower is a 2005 model.

 

[cyberslick18]

Well of the 5 after market camshafts that I brought off Amazon myself two had to the journals worked down by .001" just to fit in the engines camshaft bearings. The other have poorly finish camshaft lobes. And neither of the five oil pump shafts will fit. Plus on the last three the ACR was quite loose. On top of that I would have return the last three the company selling closed up shop soon after I got the camshaft in stock. No way to return so I am stuck with those garbage camshafts.

So personally I am not buying any more after market camshafts. Not worth it to save just $25 over my Briggs distributor price of $58.96. Once Brigg has them back in stock I'll at 5 of them for stock plus whatever I for repairs.

As for how OEM last it is the luck of the draw there too as I had one customer broken one last Summer and then again this Spring and he cuts only about 2.5 acres weekly. Then others have yet to break one like me that cuts up to 6 acres bi-monthly. I still on the first camshaft and the mower is a 2005 model.

That's kind of my dilemma. Everyone saying the design is the flaw regardless, and you get lucky or unlucky, so its a hard to pill to swallow for the OEM cam being $110+ shipping and 2-4 week delivery versus $35 and two day delivery if its going to be a crap shoot anyway. If it's a thou or two off I'll just turn it down quick, I'm not worried about the fit so much as I am the price. If I wait a month for the OEM and it just grenades immediately anyway I'm probably going to give this mower a viking funeral.

 

[Fish]

"by finding TDC and then continuing 1/4 down"
Elaborate on this a little.

 

[cyberslick18]

"by finding TDC and then continuing 1/4 down"
Elaborate on this a little.

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I'm at work so I don't have the actual B&S technicians manual, but the procedure is the same. If you google for the B&S tech manual a pdf should pop up.

The method they teach their service techs, to the best of my knowledge anyway, is to use a straight tool of some kind (screwdriver, socket extension etc) as a reference in the spark plug hole, find TDC and then continue the stroke so the piston is, measuring your straight tool as reference, .250 down the bore, and then set your clearances at this point.

I saw some debate on other forums and videos as to whether this is worth the trouble or not, so I tried it this way, and also by just alternating the valves open and close and setting clearances there, and neither provided any meaningful decompression improvement.

 

[StarTech]

"by finding TDC and then continuing 1/4 down"
Elaborate on this a little.

TDC Compression is where piston at the top of the stroke with both valves close. The following from the Briggs Single Cylinder OHV service manual. The reason for 1/4" pass TDC is to make the ACR is in the way. Personally I just use the old way where one valve is fully closed and adjust the opposite valve.

 

[Fish]

Engine Valve Maintenance & Repair | Briggs & Stratton

Looking for valve maintenance and repair tips for your small engines? Follow our step-by-step guide to remove and clean your valves for better engine performance!

www.briggsandstratton.com

I'm at work so I don't have the actual B&S technicians manual, but the procedure is the same. If you google for the B&S tech manual a pdf should pop up.

The method they teach their service techs, to the best of my knowledge anyway, is to use a straight tool of some kind (screwdriver, socket extension etc) as a reference in the spark plug hole, find TDC and then continue the stroke so the piston is, measuring your straight tool as reference, .250 down the bore, and then set your clearances at this point.

I saw some debate on other forums and videos as to whether this is worth the trouble or not, so I tried it this way, and also by just alternating the valves open and close and setting clearances there, and neither provided any meaningful decompression improvement.

I am aware of the procedure, was just wanting to find out if you meant 1/4" of the piston travel, or 1/4 of a revolution of the flywheel.

 

[Joed756]

Have you checked the crankshaft key to make sure the key isn't broken or bent, the keyway isn't degraded and the key is correct size?