Briggs 3.5

jigfeett

Hero Member
Joined
May 30, 2008
Messages
453
Points
18
Location
Pacific Northwest
Hi, just a Briggs question, I got a couple Briggs 3.5hp and a 3hp that have been sitting for years. One edger one tiller.

This is what I have done so far,
clean gas out- add fresh gas- replace spark plugs- replace air filters- clean carbs- changed oil-

I'm just wondering if it is better to just replace the carbs or actually disassemble the carbs and rebuilt them.
I'm not highly concerned with cost, I see rebuild kits for under $20 and new replacement carbs for under $35 ish and tanks under $25
If I replaced all three items it would be less than $50 but I don't know if the parts are quality.
The 3.5 does not want to start at all but the 3 hp actually runs but poorly ( surges)
The 3.5 is a YBSXS.1481HH 275076, on a 801-3.5RP McLane edger
The 3 hp is on a tiller Lawn Chief brand that has 5 Hp on the machine but the engine is actually a 3 hp.
model GIS 6772A76
I appreciate any thoughts on this.
1704905173881.png
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,932
Points
63
Do you know of this place? I feel they have the most comprehensive info on engines like this, and I have been satisfied with parts orders from them. https://www.sepw.com/

I would probably just open up the carbs and make sure they are clean. Blow out the little jets and orifices. But, a "rebuild kit" sure won't hurt anything.

I have found two chronic problems with these flat-head engines.

1) The ignition "kill" switch is very crude. Parts there often get bent so that the ignition is "off" even when you don't think it is!

2) The valves seem to "sink" into the block with age. Maybe related to the elimination of leaded gasoline? This "sinking" causes the valves to hold open a bit, making for poor compression, especially when cranking. Also, probably worse on a cold engine, before the block height grows from thermal expansion. You can grind a bit off either the valve stem or lifter, but I usually go for the valve since they are easier to get out. (Mushroom lifters require removing the cam).

I almost always just re-use the head gasket and any others that are not horribly damaged
 

jigfeett

Hero Member
Joined
May 30, 2008
Messages
453
Points
18
Location
Pacific Northwest
Thank you, I've not seen that site but will check it out.
I found the (dead) 3.5 does have spark
but even after cleanup and all still won't run
but will pop a little when the choke is set full on and throttle is about half.
 

jigfeett

Hero Member
Joined
May 30, 2008
Messages
453
Points
18
Location
Pacific Northwest
It is kind of funny that the 3.5 looks so much better cleaner than the 3 hp but the 3 hp runs and I tilled up rocky ground with no issues.

Does any one have any documents for the Lawn Chief tiller
the tag has this on it (Wizard) stock 4XC 6772 model GIS 6772A76.
It is made heavy duty with geared axle but with it being labeled 5 HP
I will guess someone at some point swapped out the 5 hp with the 3 hp
 
Last edited:

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,932
Points
63
Try this site for info/help on that old machinery: smokstak.com

It may look like it is oriented toward "antique" machinery, but there are many forums there on relatively modern stuff. Besides, in some industries like generators, things before 2000 are considered "antique"!
 
Top