Took a mower for a good run today - 2003 Masport with xts 50 Quantum
Anyway, back lawn ran great, front verge ran ok, then I left it idling on the path for about 5 minutes. Came back and put the throttle to half - bogged and died.
Primed, started first go mowed for 2 mins, then surge and dead. Fiddled for a minute, primed ran 30 seconds and died. Primed then started and stalled. Repeat and same thing.
"blocked jet" I thought, burnt my finger getting the nut off - clean as a whistle. Good fuel flow once I turned the tap on (fitted one a while ago)
Cracked the sh**s and went and finished the front with another mower.
After cooling 10 minutes, I was able to start (hard but managed) but surged.
Whilst it was running, I stuck my hand over the snorkel - normally this is accompanied by black smoke and a flood. However now it revved hard and wouldn't stall
So this would indicate an air leak downstream of the carby - loose carby or intake at the engine
Hi Tyler strange symptoms there, maybe the inlet manifold tube has a hole rubbed through it by the cowl, or the manifold has come loose where it bolts to the head. Come across those problems on several occasions. Haven't come across a Quantam with a snorkel before
Damn annoying because it did all the back and 3/4 of the front then died haha
The upper level Masports had the snorkels, and Victa had them as an option - not many people took them up on it unfortunately as its the best thing for a mower
I have a few Quantums with the snorkel ,they are a lot better at keeping dirt etc out of the engine.
If it's not making a popping noise out the muffler or backfiring it sounds like a carby problem ,I've had a few that the fuel hose was so old it would slowly disintegrate and block the main jet ,I would remove the fuel bowl and it was spotless but then when you put fuse wire up the main jet it would dislodged the small rubber fuel line debris ,then the motor would run without a problem.
The popping noise can be a non seating valve but usually if this is the case the engine uses a lot more fuel.
The popping noise with the motors I've had is mostly a sign of weak spark meaning the spark plug is faulty or the coil is faulty,the correct method of checking the ignition coil is with an oscilloscope .
I would change the coil for one that you know is good as long as the plug doesn't have a problem.
If changing the coil still doesn't fix the problem at least you have ruled that out as being the problem.
That might also explain the similar problem I have been having with my Pop's old mower - Masport MSAA alloy deck with xm50 bought in late 90s (1997?). It had an old champion plug in (and the original red painted plug in a box was in the shed).
The air filter was awful again so last month I gave it a full on tune up - blades and bolts, 2 oil changes, air filter and prefiler, a clean NGK plug, clean and lube linkages, rpm check (was a bit fast)
And once it was hot it was lightly popping. I was thinking valve or timing (considering someone hit a pair of scissors in the grass - thin short couch grass so no excuse).
I will throw in another plug and see
Its doing 2 lawns now so will probably get a 3rd oil change next time I'm there
I have seen one of the intek ohv's with a snorkel, but I wouldn't call it a modern briggs ohv. All the newer ones I have seen have carby on the left, with a few upper model exceptions
Tore the cowling off today - I hadn't done it before on this one. Only used it 2 times since I bought it
Had the thickest pile of greasy grass I have ever seen - couldn't even see the governor arm, fins all caked. And it looked so clean on the outside - lulled into false sense of security
Degreased all that - had to scrape out with screwdriver and squirted a bit of water down to get the chunks out. And then I saw the intake - split.
I always like to start the engine after any water near it so put the tube back on, put the coil back on (took off in case of water). Wrapped rope around the pulley and away it went - ran smoother than ever despite the split
Will take to it with the soldering iron and see how it goes.
I was also disgusted by how the gasket between the manifold and engine wasn't even on right from the factory - they missed the bolt hole entirely (gasket bolt hole was triangle still) - they just torqued it down without checking - the edge just sealed it.
Turns out it was made in the first few months of the Chongqing Plant - bugger
JD welded (actually permatex equiv) the cracks - all cleaned and back together - went first go and ran fine. Will mow this week now our heat wave is gone, and see how it goes
Hey Tyler, that crack looks like its from overtorquing or like you said, because there was no gasket under the hole. If you nee a manifold, let me know, ive got a few here, just pay for the postage. Cheers, Ted
Hi Tyler, I have lost track of the number of different types of manifolds Briggs have used, all the same just a bit different. Always does my head scratching through boxes of bits trying to find the one that will fit.
- I was thinking they were all classic 35 ones, but turned out 2 were quantum. 
