briggs and stratton classic/sprint engine help please

[jimmy80s88]

hi all, i was hoping you guys could help me as im trying to get one of these small engines running correctly but getting frustrated. the engine once running makes kind of a 'putt' sound randomly and ive seen this same type of engine do this for other people. ive changed the diaphragm and gasket, cleaned the carb, changed the spark plug and filter, checked the flywheel key is ok, tried another ignition coil and yet im still getting this issue. please if someone knows the answer on these engines i appreciate your help.

[Mick]

Hi Jimmy, and welcome to TGMF.

From your description it's rather difficult to diagnose. These engines are notorious for diaphragm issues, and sometimes even after changing the diaphragm and gasket the issues persist.

Does it belch black smoke?
Does the engine bog down and run rough when moving the machine backwards and forwards?

If yes to either of those questions you could try fitting two gaskets on top of the diaphragm instead of one.  In fact if you still have the old gasket and it is in good condition you could put that on top of the new one.

[jimmy80s88]

hi mick, thank you for your reply and help. no it does not belch out any black smoke at all, it doesnt do the annoying reving up and down, just this other noise i mention i called it a 'putt' type sound. I have today tried another gasket as well on top like you say and its still the same. im starting to think ive tried everything but of course there must be something im missing. its got the black o ring and white retainer clip on the inside of the carb so thats sealing, ive made sure those 2 bolts holding down the manifold are tight and not cracked. like i say changed plug, air filter, flywheel key is fine not broke, im at a loss???

[Mick]

Don't suppose you have a video of posted somewhere, like I said it's a job to say what it is without hearing it.

You seem to have covered most of the problem areas.  I guess the next step would be to check the valves, maybe give them a grind in and reset the gaps. Also make sure a valve seat isn't moving about when it's running.

[jimmy80s88]

hi, i will make a video on my phone and may be able to upload it to youtube i will try later on mick. As for the valves that's starting to sound beyond my capability's lol. i have 2 of these mowers with this engine and they both make this sound its so frustrating.