Small Engines (Lawn Mowers, etc.): Briggs and S 3.5 Hp L engine, piston ring, diapragm

Question
-------------------------
Followup To
Question -
Hi Eric.
94908 type 5911
Have hot starting difficulty with this engine, choke seems to be working correctly, mixture is set as it should be, Diapragm and spring at carb is fine, pick up tube's clean. never starts for me when hot. Noticed oil fouling on the plug, would it be time for a piston ring set to go in, What would I go for assuming it never had ring's done before +.010?
Thanks Joe
Answer -
.010 over would probably work.  What is the type code?

Since you mentioned a diaphragm and spring, you must have a metal tank.  Is the carburetor also metal?

If so, these are prone to warping.  You can pull off the pickup tube, it's difficult, but it can be done with a pair of plyers.  Once the tube, or tubes are off you can use a stationary belt sander to lightly sand the carburetor to "true" it up again.  A flat hand file also works, but it just takes longer.  Briggs also sells a kit, a small roll pin and teflon like washer, to install in some carburetors.  This is suppose to help solve the warping problem.  

Let me know about the carb.
Eric

Thanks for the reply Eric.
interestingly you mentioned warping of the carb, it does have a metal carb and tank btw, one of the carb hold down screws has been missing, I wonder if this has helped along any warping, never leaks fuel, but could be leaking vacuum. Going to work on it during the weekend, I'll let you know how it goes.
Joe

Answer
Most of the warped carburetors I've found don't really leak gas like you found.  Rather, they seap, very slowly, you hardly notice it.  In fact you probably will only notice it by the dirt that seems to accumulate in that area.  Another interesting factoid is that some Briggs carburetors have a screw in the center of the carburetor to help prevent warping...not the air filter screw, but an actual screw.  These are very rare.

Let me know if you find the carb is warped.
Eric