Cadet 76 running rough...

[bbrewer]

Hello all,

I have a Cadet 76 that is running rough. I first cleaned the carb. It runs fine at high idle, but when I lower the rpms it runs rough and occasionally backfired. So I ordered a NOS B&S carb kit off of ebay. It arrived today so I cleaned it again, and installed the kit. It does run better throughout the rpm range. But still doesn't run as smooth as I would like. I should also mention that it has a new plug also. Could it be that the carb just needs adjustment? Ir so how do I adjust it? Thanks for any help.

Brett

 

[kmcconaughey]

Brett, one thing to check is if the choke/throttle control is working properly. The choke control is built into the throttle control on the 76. Make sure that the linkage is operating correctly. Also check the fuel line from the fuel tank, it could be deteriorating and getting some small bits of rubber into the carb. If it's got the original fuel line or if it's even 10 years old it might be best to just replace it as that's a low cost item.

 

[mbounds]

Kraig, Brett: That Model 76 has a Briggs & Scrappum engine.

They are prone to valve sticking (MMO helps a lot here) and you know what the dreaded B&S flywheel shearpin will do for the timing. The backfiring indicates probably one or the other..

Myron B
CCSupplyRoom

 

[bbrewer]

Kraig, the throttle linkage seems to be working freely. I did replace the fuel line, and shut off valve...

Myron, I do have some MMO on hand, I will run some through it. What about seafoam, is this any better than MMO? Thanks to both of you for the help so far.

 

[klejeune]

The seafoam will clean it up and the MMO will keep it lubricated to keep the valves from sticking.

 

[mbounds]

Kraig, Brett...I used the term "shearpin" but am talking about that dratted little ole aluminum flywheel/crankshaft key which will often partially shear and cause much frustration with the timing issue/backfiring etc.

Myron B

 

[kmoe]

Myron is correct. A partially sheared key will make a B&S run like crap. It is possible that a valve is not seating properly, but it is not the most likely cause. Mine ran badly even though the key looked fine. After pulling the flywheel I found that it had just barely sheared, not enough to see from above, but enough to have the ignition timing off. Since replacing the key it has run like a new engine and given me three years of mowing/snow duty.

 

[bbrewer]

Well Kyle, that could be the problem with mine... Where would I find a replacement flywheel key? Is it hard to get at it to replace? Thanks.

Brett

 

[kide]

Brett - they usually come in a blister pack, cheap. I think you'll find them not only at any Lawn and Garden shop, but almost any L&G parts display in tractor shops, chain stores, probably even Wally World and drug stores (kidding about the last two - I think)

 

[bbrewer]

Kendell,

Sounds like they are easy enough to find. But how easy are they to get at and install?

Brett

 

[kmoe]

You will need to remove the gas tank, so you can take off the engine tin. Then you will need a strap of some sort so you can hold the flywheel while you loosen the sprague clutch for the pull start. That clutch also acts as the flywheel nut and needs either a special tool, or you can use a piece of 1x2 oak and a hammer to get it loose. Just put the oak stick on one of the clutch ears and hit it with a hammer. You probably won't need the strap to hold the flywheel but I'd have one on hand just in case. After the nut is off you can VERY CAREFULLY use a pry bar to GENTLY between the flywheel and the engine case. It would be better to use a flywheel puller if you have one, but the pry bar will work if you go slow and easy.
You can get the manual for that engine here.....
http://www4.briggsandstratton.com/display/router.asp?docid=67016

 

[kmcconaughey]

Here's Kyle's link in an easy CLICK HERE format.

 

[bbrewer]

Well it looks like it will be a tricky procedure. But with a little patience and this forum, I think I can get it done... Thanks Kyle for the help.

Also want to thank Kraig for the link.

Brett

 

[mbounds]

Brett: If you haven't done this before, please note that you should NEVER put any pressure on or strike the flywheel fins !!! They will break off and there goes the balance and then a new flywheel. This does not cause a flywheel removal/reinstall problem if you are aware of it.

Myron B
CCSupplyRoom

 

[bbrewer]

Myron, this is my first time. But I will keep that in mind. Thanks.

 

[kmoe]

Kraig,

Thanks for fixing the link. It should have posted as a clickable link

It's not really all that tricky. Just follow the procedure and go slow. Brute force and speed will put you on the road to buying a replacement engine.