Older briggs loves to surge!

[dart451]

Put on a new carburetor on a Briggs 135202-0258-01...needless to say the linkage/governor system is complex to get back together. But, I do have it all back together but the carburetor surges badly. Can't seem to stop it no matter what I do. I did notice that the new carburetor I bought only has a Jet screwed into the carburetor adjustment needle that is on the older carb. I choke the carb some...I know if the mixture is lean, that usually makes it run smooth but this one doesn't. Only thing I can think of is it's a bad carburetor. Checked the spark plug also, even changed it out and checked the gap, all looked good. Any thoughts?

[38racing]

Have you checked valve clearances?

[bgsengine]

Put on a new carburetor on a Briggs 135202-0258-01...needless to say the linkage/governor system is complex to get back together. But, I do have it all back together but the carburetor surges badly. Can't seem to stop it no matter what I do. I did notice that the new carburetor I bought only has a Jet screwed into the carburetor adjustment needle that is on the older carb. I choke the carb some...I know if the mixture is lean, that usually makes it run smooth but this one doesn't. Only thing I can think of is it's a bad carburetor. Checked the spark plug also, even changed it out and checked the gap, all looked good. Any thoughts?

fixed jet carburetor is a royal PITA to deal with when putting on these older engines - You have to make sure you have *ZERO* air leaks - which typically are found around the intake gaskets (did you use double gasket?) - and like 38 says , valve clearances can affect that too. if it is mechanical governor, perhaps a static governor adjustment may help as well.. also, since some of these carbs are sold to fit 5 HP, but are actually for 3.5 HP - they'll be jetted wrong - so you will want to verify that the carburetor is actually for the engine you put it on.. (especially true on aftermarket carbs) - the actual replacement carburetor from Briggs would run around $125.00 or more and even those can end up with excessive lean problems. typically

[bobodu]

Put a "Tecumseh" sticker on it and call it fixed....

[KE4AVB]

Does it smooth out when you hold the throttle vane steady? This usually tell you if it is carb or governor issue. Just remember if the idle speed is set too low it can cause this problem too.

[dart451]

No, the motor does not smooth out if I hold the governor...I have not checked the valves...damn thing looks like it was never used hardly at all but it's certainly one of the older engines. I like the last response...put a Tecumsi sticker on it and say it's fixed!

[RoyM]

Then the carburetor is the problem, not the governor. Is it OEM or an aftermarket? Is the fuel fresh and clean?

[dart451]

It's a cheap aftermarket

[KE4AVB]

Then it is time for the micro bits and figure out if it is idle mixture pilot jet or hi speed jet that is too lean. I would think it is the idle pilot jet being too restrictive but don't forget if the idle speed is set too low can cause this as most engine runs at near idle mixture when not under load. I had several engines this year where the idle speed was set too causing problems.

[creia]

Put a "Tecumseh" sticker on it and call it fixed....

That has to be one of the most witty and humorous replies I've ever seen on this forum! I've worked on a lot of the old Briggs and Tecumseh flatheads and there is some truth to that statement as well...
Michael