Valve Lapping?

So I have reason to believe I burned up my 12hp B&S's valves. How do I go about lapping them by hand (no tool)? I measured, I've got .070 on intake, and 0 on exhaust.

Thanks!

What precisely do you mean with those number?

Get yourself a lapping tool, they're cheap. It's basically a suction cup on a wooden stick. You might be able to improvise one. You will also need lapping compound.

What precisely appears to be the damage to the valves/why do you believe they are damaged.

Is that the amount of valve lash(clearance) you have? Sounds off, did you measure it with the piston on top of the compression stroke?

If so, you need to grind the end of the exhaust valve to gain clearance. I don't have the book right now, but I'm sure somebody here has the correct numbers. That may be all it needs to run.

To lap valves, take the springs and keepers off the valves. You need to have clearance on both valves so they don't bottom out on the lifters.

I'm not sure where you would buy lapping compound, I have some left over from work. Probably want a fine compound. Mix it with some motor oil, till you have a paste. Put this on the valve seat, insert valve, hold it against the seat, and spin. Looking for a shiny ring all the way around the valve and valve seat when done.

The tool doc mentioned makes it much easier, but you can do it without a tool. Just a pain to spin the valve.

Shoot, I want thinking of compound. I just spent my last $4 so I'm definitely not getting a tool.
So the basic idea is to get the valve and the seat to seal perfectly? I had 85psi of compression.
Also Doc, I had been running a 4" straightpipe. Finally my engine started stalling out. I have a thread under B&S.

In addition to stretch's good advice-

Be sure to thoroughly clean everything when done. Lapping compound is abrasive, and it probably goes without saying, but you don't want liquid sandpaper floating around your engine...

Check valve lash first, before doing anything else. Do you own a set of feeler gauges? Give me your Model Type Code, and I'll give you the lash specs. Once you have successfully adjusted the lash, THEN perform a compression check. The reason for adjusting lash to spec first is because of the compression relief mechanism on the camshaft. ALSO-

With the compression relief in mind, you MAY get a false compression test result, as the machanism does it's job. For a TRUE read, spin the engine BACKWARDS and check. This defeats the mechanism.

That said, 85 PSI should allow the engine to run decently enough.

Ill get the specs for you in the morning. The lash is the space between valve and tappit, right?

Also I couldn't spin the motor backwards fast enough to get a reading. This is an older model (late 80's?) so does it have a compression relief?

I don't need the specs- you do... lol
To spin the engine backwards, try wrapping a rope around the pulley or flywheel.

ell I'll get the model number so we can find the specs. that's nice with the really olf engines, my Kohler says the points gap and valve gap right on the side

Get a longer pipe on there bro. 4" Isnt enough unless you put an exhaust on. I would do 12" with at least 1 90" bend in it, and thats still pretty damn short.

Yup, I learned that the hard way. Here's my model number Doc, If you could find the correct lash that'd be great. It's a B&S 281707

Intake- 0.005"-0.007"
Exhaust- 0.009"-0.011"

And that's the distance between the valve and tappit, right?

My feeler only goes to .015.

Let's back this train up a bit- Just to verify- is your engine an L-head, or an OHV? I think I might have pulled the wrong spec- Gimme a few minutes.

-0.015 is HUGE! You need a thinner gauge set if that's the smallest you've got.

Yup, valve in block. An older model too. I'll see about the feeler gauge... Maybe I can borrow one.

That's what I thought. Okay- spec post edited.

Alright, I'll be back in an hour to post my results!

Also if the valves do need to be adjusted, how do you do that? It's not like OHV where you just loosen a screw.

If clearance is less than specified, grind end of valve stem to obtain proper clearance.
If clearance is too much, replace valve or cut valve seat to obtain proper clearance.

*facepalm+ My gauge goes to .0015 not .015.

Either way I have no clearance. I'll try to take them out and grind. I've never taken out an exhaust valve, just intake.

Doc, you got any tricks for keeping the valve springs compressed?

Without a valve spring compressor, I have used everything from a couple screwdrivers to a big modified C-clamp.

I'm working with screwdrivers. Clamp is a good idea.