Compression release briggs vtwin model 441777

[Forest#2]

Did not see where you tried to adjust the valves lash to minimum specs BEFORE you took it apart? (especially the intake valves)

 

[TobyU]

You certainly should not have taken the engine apart before you check the easier things first.
A lot of these Briggs v-twins do not have a compression release finger like the singles do.

The first thing you do on any of these is check the valve adjustment because normally you'll find it's two to three times wider than it's supposed to be and that's why you have no compression release.

On the singles with the finger on the camshaft for the acr, you can just tighten them up to zero lash and turn them over by hand and watch the intake valve bump open after it closes. That let you know the ACR is working. If you have one and you set the last to zero like that and it does not bump at all then you know the ACR is busted and it really needs a camshaft.

 

[ronnierepairman]

Did not see where you tried to adjust the valves lash to minimum specs BEFORE you took it apart? (especially the intake valves)

ended up putting in a new cam with the compression release..
runs like a champ now..
one very odd thing though, the valves coming out of adj, or the cam wearing a bit ( this mower is old )
over time will increase the compression.. my friend said it was getting harder and harder to start.
when i put it all back together.. it sounded great cranking over, but wouldnt start.
I checked spark and it was good.. has awesome compression. sprayed carb clean in the carb and nothing.
my buddy noticed sparks under the flywheel cover when it was cranking..
i found the starter was really loose and it was obviously causing a flaky ground which is why it was sparking. so i tightened up the mounting bracket bolts and then it fired right up.. very odd, the starter bracket should have had no effect on starting. maybe just coincidence..

 

[bertsmobile1]

The bad connection at the starter would have cause it to turn slower particularly when the resistance to turning was the highest
So you get a bigger decompression than B & S intended so not enough fuel to support a combustion

 

[ronnierepairman]

The bad connection at the starter would have cause it to turn slower particularly when the resistance to turning was the highest
So you get a bigger decompression than B & S intended so not enough fuel to support a combustion

it was still turning over fine.. new battery.. and even better than before with the compression release cam.
its very odd..
im thinking it was coincidence.

 

[ronnierepairman]

You certainly should not have taken the engine apart before you check the easier things first.
A lot of these Briggs v-twins do not have a compression release finger like the singles do.

The first thing you do on any of these is check the valve adjustment because normally you'll find it's two to three times wider than it's supposed to be and that's why you have no compression release.

On the singles with the finger on the camshaft for the acr, you can just tighten them up to zero lash and turn them over by hand and watch the intake valve bump open after it closes. That let you know the ACR is working. If you have one and you set the last to zero like that and it does not bump at all then you know the ACR is busted and it really needs a camshaft.

good to know.. I dont fix these for a living, ive fixed a few motors with failed ACR and obviously the symptom is
like a very weak battery.. take the plugs out and it cranks fine. so I assumed it was a broken ACR.
this was the 1st time i came across a motor with no mechanical ACR..
so thanks for the info.. next time ill check the lash 1st.. that said, i think this cam was worn.