Briggs V-Twin wont start after sump gasket replacement.

[JasonRay]

Hello-

I replaced the sump gasket and seal on my B&S Intek V-twin (John Deere Branded, probably does not matter). After it is back together it will not start. I have spark, and I have fuel to the carb. It will not start if I mist fuel into the intake or use starting fluid. I even removed the carb and sprayed ether into the intake on the heads. Nothing, not even a pop. I took photos of the choke and throttle connections and put them back exactly how they were.

While I had it apart, I removed the cam to get some debris out of the sump area. But, I put it back exactly as it was, timed the same was as in the photo that I took beforehand . Could there be something that I messed up when I took the cam out and put it back in? Everything went back together with no issues, no extra parts left over I watched tutorials of people who have removed the cam and put it back in, I did it the same.

When it cranks, its spinning nicely. There just isn't any combustion, or even signs of it.

I really dont want to have to open it back up again, but I will if needed.

Any help is appreciated,

-Jason

 

[JasonRay]

Good morning-

I would like to check compression to rule out a timing issue/damaged push rods. What is the best way to do this given the compression release on these engines.

 

[JasonRay]

Would anyone have the Torque spec for the rocker arm bolts?

 

[Rivets]

I would do the following in this order.
1. Open the engine and double check that you aligned the timing marks on the crank and cam shafts.
2. Double check your valve clearances.
Some people want to reverse these two, but I like to work from inside out, as you will have to recheck valve clearance any time you open the crankcase.
3. If it still won’t fire I would go to an auto parts store and rent a leak down tester and perform a leak down test to verify that there a no cylinder leaks. Many have a free loan policy, you put down a deposit and it is returned when you return the tool.

 

[VegetiveSteam]

I really dont want to have to open it back up again, but I will if needed.

Any help is appreciated,

-Jason

You can check valve timing without opening the engine back up by checking valve over lap. Take out the spark plugs so you can hopefully turn the engine by hand. Remove one rocker cover and bring the piston on that side to TDC exhaust. If properly timed, valve overlap is what you get when the piston reaches TDC on the exhaust stroke. At that point both the intake and exhaust valves will be open just slightly as opposed to both being closed as they would be on TDC compression stroke. If you're able to move the flywheel back at this time, your rocker arms should tetter totter. If the engine is in proper valve time you will only get that teeter totter situation with the piston at TDC exhaust stroke. I've attached a link to a youtube video that explains valve overlap. They obviously are not working with the same engine you have but the principle is the same. Where they have cam lobes and what he calls a bucket you have rocker arms.

This is a need to know troubleshooting technique if you're working with an engine where the cam gear is pressed on to the crankshaft and not keyed as the case with a Kohler Command. If the crankshaft on one of those engines would turn in the crank gear the engine would be out of valve time but the timing marks on the the crank gear and cam gear would still be aligned. This is the only way to easily know that engine is out of time.

I hope this helps.

 

[Rivets]

I would not use that technique because I like to see the timing marks. One tooth off cannot be detected by most DIY guys. Read my signature.

 

[OldDiyer]

Rivets, Question why do you have to check valve clearances after you replace sump gasket and lower crank seal? If you don't rotate anything what changed to make you have to do this? Just wondering because I am about to undertake a gasket replacement as well on a v twin just waiting for parts to get here.

 

[Fish]

So have you removed the valve covers yet? Make sure that the pushrods are in place.
Here is a handy web site.

Briggs and Stratton Valve Clearances

outdoorpowerinfo.com

 

[Rivets]

I’ve always taught that when you remove a part that can affect another part recheck. In this case removing the sump affects cam and crank position when it is reassembled. We are talking thousands of an inch with valve clearance and in this case four valves. I don’t mind double checking my own work, especially when troubleshooting, as it has saved my butt more than once over the last 50 years.