Briggs & Stratton 6.75hp valve adjustment

[maddogandnoriko]

I have read a number of places and multiples times that a main reason for a mower running poorly or "knocking" or "pulsating" or hard to start is that the valves need servicing. Most of the people in my area have the Briggs 6.75hp motors. I have one here now that is hard to start. I looked for some advice on how to service the valves But didn't find much for the smaller motors, just the riders. So could someone post a link or two or hints on how to adjust the valves?

My mower is:
Mower model#: 917.370430
Engine model #: 126M021525-F1 11110858

Thank you very much,
Todd

 

[Fish]

Your engine appears to still be an old L-Head, so the valve adjustment isn't quite so finicky.

Start over and tell us the history. Like: It was running great until.........., Or, I just bought it at a garage sale and never heard it running before......
Or, I pulled it off a push mower and mounted it on my pressure washer...........

Details like that, and exactly what you have to do to get it started.

Does it knock, like you mentioned.........

Give it all of the history you can, and we will be able to better help you.

 

[tybilly]

speaking of wich,ive not done a valve service on those recessed valves,does the normal lapper suction cup work on those?

 

[Fish]

speaking of wich,ive not done a valve service on those recessed valves,does the normal lapper suction cup work on those?

I really don't "lap" the valves like most folks, I use Neway valve and seat cutters, one angle is 46 degrees, the one on the valve is 45 degrees, that 1 degree difference
is the seal, and lapping destroys that. I do a light "lap" one part stroke, to see where the valve is sealing at, but that is all.

 

[reynoldston]

It looks like the question is how to adjust the valves on a L-head engine? You very carefully grind the end of the valve stem off. Its a one shot deal because if you grind too much its not repairable.

 

[davbell22602]

I really don't "lap" the valves like most folks, I use Neway valve and seat cutters, one angle is 46 degrees, the one on the valve is 45 degrees, that 1 degree difference
is the seal, and lapping destroys that. I do a light "lap" one part stroke, to see where the valve is sealing at, but that is all.

Maybe you should do photo write up on how you do that. I use lapping compound and the seat cutters. Lapping compound is for taking the pits out of the valve face. The cutters is for the valve seats. I use the Napa water mix valve grinding compound.

 

[reynoldston]

My valve grinding set has to be old. It comes in two different outfits. The set to grind the valve seats has different stones that are all different sizes and angles. You spin the stones with a machine that looks something like a angle drill. Now to grind the valves is a special valve grinding machine just made to grind valves. This machine also has a adapter to grind the valve stems. I got this outfit used years ago to do cars and trucks so I don't know how old it is. I use the valve grinding compound just for a final finish.