Briggs 14.5 high compression problems

I got a 97 or 98 mtd for 30$ motor was said to run and tranny case was cracked..ditched the vari drive and made it into a mudder with a dofferent tranny. Well the motor doesnt run for me..the 3 strokes turn fine but as soon as it gets to the compression stroke it is so hard to turn over, even a truck battery wont do it. I dont know what the problem seems to be..i looked at the valves they seem fine. Its a 97or 98 briggs 14.5 hp ohv the model number is 287707 and i have the manual for it. Anyone got any ideas what it is? Thanks

Did you look at the valves, or did you actually measure valve lash? Insufficient lash very commonly cases what you describe.

Also check all your wiring connections including grounds. Failing all that, your starter may be going...

Doc Sprocket wrote:

Did you look at the valves, or did you actually measure valve lash? Insufficient lash very commonly cases what you describe.

Also check all your wiring connections including grounds. Failing all that, your starter may be going...

I dont think its my starter but ill try n measure the valve lash its got to be something with the valves unless its a thrown rod bearing

If you look in our engines section, you will find links for service manuals. Download yours for specific instructions on checking and setting valve lash.

It's possible that the valves have been adjusted wrong. It's common practice to adjust valves with the engine at TDC (top dead center), but on these (and most other OPE) engines the engine needs to be 1/4 past TDC. This allows the built-in decompression to work properly after valves are adjusted.

I did this the wrong way once; I couldn't get the motor to crank over even with a truck battery jumping it. Readjusted the valves at 1/4 past TDC and it cranked over fine with just the mower battery.

The Briggs & Stratton website mentions this for valve adjustment.

B440 wrote:

It's possible that the valves have been adjusted wrong. It's common practice to adjust valves with the engine at TDC (top dead center), but on these (and most other OPE) engines the engine needs to be 1/4 past TDC. This allows the built-in decompression to work properly after valves are adjusted.

I did this the wrong way once; I couldn't get the motor to crank over even with a truck battery jumping it. Readjusted the valves at 1/4 past TDC and it cranked over fine with just the mower battery.

The Briggs & Stratton website mentions this for valve adjustment.

I agree definitively. This is the most common prob with an OHV. They will need to be adjusted just about yearly. Dunno why they go out of adjustment, just know they do.

No argument here.

As for the adjustment... Wear. Cam wear, lifter wear, rod wear, etc etc etc. Normally, these things would go completely unnoticed, if not for the very obvious effect with the compression relief.

unscrupulous mechanics will often tell you they had to replace this or that, and charge you a lot of money, when all they did was adjust the valves... 15 ninute job. I caught someone locally pullin that crap on the old ladies next door... I demanded the old part... He brought out a part FOR A COMPLETELY DIFFERENT ENGINE! (the governer for a flathead) I busted his chops, called the owner in, got the man fired (this was a reputable place, the guy was skimming the extra)

B440 wrote:

It's possible that the valves have been adjusted wrong. It's common practice to adjust valves with the engine at TDC (top dead center), but on these (and most other OPE) engines the engine needs to be 1/4 past TDC. This allows the built-in decompression to work properly after valves are adjusted.

I did this the wrong way once; I couldn't get the motor to crank over even with a truck battery jumping it. Readjusted the valves at 1/4 past TDC and it cranked over fine with just the mower battery.

The Briggs & Stratton website mentions this for valve adjustment.

Buy 1/4 past TDC I hope your referring to 1/4 INCH past TDC. Not a quarter rotation. The book calls for 1/4 inch past TDC.

Isn't it funny how we all just ASSUMED that he MEANT 1/4" and not 1/4 turn?

if i was you i would pull the intake off remove the valve inspection plates turn the engine over by hand and make sure all the valves move if one dosent i suspect the cam might have a broken lobe

Hmm. You're right. What I said could be interpreted both ways. I wonder what would happen if you went 1/4 turn?

B440 wrote:

Hmm. You're right. What I said could be interpreted both ways. I wonder what would happen if you went 1/4 turn?

It would probably have very little compression.

Doc Sprocket wrote:

Isn't it funny how we all just ASSUMED that he MEANT 1/4" and not 1/4 turn?

Lol for a second I thought a quarter turn but then I re read it and knew what he meant. Just a clerical error

Is it hard to turn 5-10 revolutions by hand? If not then your starter is croakin