OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Four Stroke Lawn Mower Frames Briggs engine hard to start

Hi Guys, I have a fully reconditioned mower shop briggs and stratton engine (375) set up on a good base. The engine is too tight to start with the rope rewind starter. When i remove the spark plug it winds over great. When i apply my finger over the plug hole the compression is so strong it become difficult to turn the starter.
is there a running in proceedure or something to loosen her up a bit?

I wonder if the mower shop might have made an error (I don't say they have, but it could be worth checking). The B&S engines normally have a feature they call EzySpin, which holds the inlet valve open 0.010" during the first half of the compression stroke. Because of that feature it is important to check the tappet clearance with the engine on top dead center on the firing stroke. You might check that valve clearance yourself, in case they set it with the camshaft in the wrong position. If they set the clearance with the camshaft on the EzySpin part of the inlet valve cycle, they will have disabled the EzySpin feature and made the engine rather difficult to pull over.

The other obvious possibility is the one you suggested: the engine could be too tight. However you said it spins well with the spark plug removed, so that sounds less likely.

Do you have a blade plate on the machine?

Can the clearance be adjusted?

dristo72,

I agree with grumpy and suggest that you correct the valve clearance. You will need to remove the head and valves once you check the clearance and then you will need to grind the end of the valve in order to adjust it.

Joe's question is valid, as usual: if you are trying to pull a light-flywheel engine over without a blade plate fitted, it will be a bit more difficult than usual. The engine's internal momentum helps quite a bit in getting it over compression.

Being on the lazy side, I'd try a preliminary test before following Bruce's advice and removing the head. If you just remove the valve chest cover you can put the engine on top dead center of the firing stroke (put thumb over plug hole to make sure you are on the firing revolution, not the pumping revolution) then check the clearance of both valves with feeler gauges. If a sloppy mechanic has set the clearance with the camshaft on the EzySpin phase, you will find an enormous tappet clearance on one of the valves. If this has happened, it means the mechanic ground 0.010" too much off the valve stem, and you will have to replace the valve.

are you sure there is nothing blocking the intake and exhaust ports?

Thanks guys, i will on the weekend have a look at it and will let you know. Its too good of an engine to discard.
Cheers