40 thoughts on “All About Briggs & Stratton Synchro Balance crankshafts and how to remove counter weights

  1. hello i think you do great easy vidios to undastand..i have an 8hp briggs in bits .i was wondering if there was a bolt on the end of the dog bone i see how it fits up but unsure if parts are missing?……….keep up the vidios

  2. Thanks! I always try to keep them as simple as possible. There's only 1 bolt on the crank, the long 1, the other end of the dogbone just slides onto the stub in the block, no bolt. Will Do, i just put up a new one today of a old start of my 12 horse briggs. Thanks for Watching!!!

  3. Hello,

    Thanks so much for taking the time to make these videos for us. I have a quick question. The ends, or shafts on my crankshaft are a bit rusty. What do you recommend using to clean the rust off?

    I have a wire wheel, but don't know if that will take to much off, or if it even matters? Appreciate your time, and any help you can offer. Have a great weekend, and thanks again for helping us out with these videos.

  4. No problem, its a fun hobby! Yeah if you take to much off it will make it fit loose in the bearings, I recommend using sandpaper, and kind of like cup it in your hand around the shaft and turn it back and forth, use about a 220 grit paper, if its really really rusty then go with 100 or so. I would not go below 100 grit. A wire wheel would probably scratch it up to much. your welcome! Thanks for Watching!!!

  5. If it was a overhead valve engine i'd say it would be the head gasket, but its a flathead so its not that, what probably happened (very very common by the way) is when you shut it off the float stuck or the needle valve didn't seal in the carburetor and it flooded the crankcase with gas (gas ran past piston into the oil, making it act like there's to much oil in it) don't run the engine anymore, check the carburetor to make sure the float is working free, then do a oil change>>>>>>

  6. then start it and it will probably smoke for a few minutes but it should clear up after all the excess oil is burned out of the muffler, if this doesn't help write back and we'll figure something else out! thanks for watching!

  7. If it is a flathead motor, a blown headgasket will not cause it to smoke/burn oil, because the headgasket only seals the head to the block, there is no oil being sealed off by it (not like a OHV motor), but it does sound like it needs a new headgasket, which should help the backfiring problem, but I don't think it will help the smoking problem, sounds like its just burning oil, replace the head gasket then we'll go from there.

  8. I replaced the weights and the dog bone on my B&S. Started and ran great for about 2 min and then bang! Took apart to find dog bone broken in two, again. The pin holding the end of the dog bone (the end away from the weights) in place was laying in the bottom of the crankcase. There appears to be nothing that keeps this pin from falling out of the crankcase and out of the dog bone. When the pin falls out, one end of the bone is loose and breaks. Any suggestions? Your videos are great!

  9. oh no! I've never seen that happen before, its supposed to be like pressed into the block so it can't move or come out. The pin will need to be fastened somehow to the block again, I don't know what the best method would be right off hand, pressing probably won't work since it done came loose, can't weld it, if there was some way to drill through the block where it is, then tap it and put a bolt through it? I don't know what to tell you! i've never had that happen. Thats about all i can think>>>

  10. thanks for the quick response. I actually found another site where a guy was asking about the very exact thing – in 2006. After the second dog bone he said he was going to scrap his engine. On the way to the Snapper Store now to see if they can explain it. A glance at the pin(s) look like both ends are the same, but they are not. Slight difference to the bevels at the ends – one end is slightly more blunt. There appears to be nothing inside the hole to press the pin into.

  11. No problem! Yeah, I hate to see a engine scrapped. but sometimes they just can't be fixed. I hate to say this but the only thing that comes to mind is degrease it really really good then JB weld it, but thats chancy might last the life of the motor might last 5 minutes, just don't know haha It might work, If it was mine, i probably would try it. but thats up to you!

  12. your welcome! i hear ya! I did a 4 part video on rebuilding a 12.5 (same as a 12) horse briggs, i go into alot of detail on it. thanks for watching!

  13. I do but I'm not willing to let go of them haha, I have a 11 horse block that needs bored out, and i'm saving the crankshaft for that project. sorry about that, you might want to check on ebay, parts pop up on there all the time. Thanks for Watching!!!

  14. My friend has a syncrobalanced 12 hp on a gokart. We run it un governed. It's been going strong for a couple of years. No knocks doesn't run hot. Oil is never over dirty. We may get around to removing the syncrobalancer but it's never failed yet.

  15. Do you have to use those counter weights? I have a set of the other style. The kind that doesn't have a rod to hold it in place. Can I use those counter weights or do I need to use that kind?

  16. Hey man, been a while lol. Do you happen to know the part numbers for the synchro bearing shells? I'm going to take my 12 HP apart soon because with ear plugs in I can hear a slight bit of rattle come from the engine. Can't really hear it without the ear plugs in. Figure I'd better check it before something happens, especially with about 1,000 hours on the engine.

  17. good video but you never put grease in an oiled bearing race it will repel the oil and you will seas your engine. Not to be rude but that is the worst peace of advise you could ever give someone rebuilding an engine. Never put grease on any machined surface if its meant for oil it will seas up in a matter of minutes.

  18. I just ordered some of those counter weights off eBay cause after 20 years the weight closest to the flywheel was worn about a 1/4 inch. crazy I'm surprised it didn't come apart on me I'm going to up load a video when the weights and gaskets get here in about a week.

  19. The reason I watched your video is because I'm trying to see what happens if you don't run the synchro balanced counter weights I'd rather not put them back in and just run the crank.

  20. Yeah I saw that in your video the brass counterweights that take place of the synchro balanced counter weights I was looking at that but I had already ordered the original counter weights when I heard of brass counter weights. I didn't set up the engine for racing I just did pulley swaps so I don't think I have anything to worry about I don't even run the engine above 1500 rpms half the time except for when I'm in the mud or going up the hill I might punch the throttle down but besides that the RPM's don't get up there too high.

  21. Hi thanks for the great info found in your videos. Great job. I too had the counter weight closest the flywheel excessive wear problem and can't believe it still ran. I had an extrA counterweight but my problem is the rear replaceable counterweight journal indeed needs replacing but can't find one any wear not even on the engine diagram for this model. Can someone tell me wear I cAn find one? I would really appreciate some help.

  22. I race model 19 briggs motors. Is their away you can tell if it has the synchro in it or not without knowing the exact full model number and without removing the sump?? Thanks, Don

  23. I think it would be neat if you haven't already made a video on what to look for and look at when you're considering buying a used riding or push mower like look at the oil tires general condition of lawn mower and maybe talk about how much u should give ( ball park). Just an idea. Thanks

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