I just got my new prop and got it all put it on and I was goin to take the boat out for a spin. I started it up was letting warm up and it starts makling really crisp pop pop noises the rpms dont cahnge when it does it but it doesnt sound right it sounds like its really hard on the motor. The more I rev up the engine the louder and harder the pops get. Im not in the water I was just warming it up at the house its -10 here but I have noticed that sound b4. Could really use some help no Idea what it is and I dont want to wreck my new motor. The motor is a 09 MBHD4000 Thanks

So you changed the prop and now the exhaust pops? I'm confused.

Well I havnt ran the boat in awhile and I have noticed this pop I thought a little before but it was when I was running wide open and it was hard to tell what it was. So now today I go and run the motor and now its poping really hard right out the exhaust the best way to describe it is that is sounds like popcorn popping the back of the exhaust. It does it at idle and gets worse as i give it more gas its a very hard crisp pop. Is their any way to put a sound clip on here

You might want to check the valves to see if they need adjustment.How many hours do you have on the motor?

It could be dat you are runnin rich (too much fuel compared to air mixture) and da poppin you hear is da un burnt fuel dat is combustin in da exhaust.

If this is a new motor, they recomend to adjust the valves after so many hours.

I would try pulling the valve cover and making sure the valves are set right, I am not sure but I think briggs calls for an adjustment at 50 hours.

I could try that. I had to pull the crak case cover about 5 hours ago because I had a oil leak out the bottom left corner the gasket had a slight tear in it no Idea how it got their. I dont think I moved anything but is their anyway I could have screwed up the timing on the motor. I didint think I did because it stars and idles so easy just putting it out their.

I dont think that you messed up your timing, when an intake valve isn"t set right or it is leaking it makes a poping noise like you are describing.

Thanks to all the quik responses. Does anyone know what the valve clearance should be set too and basicly how to do It I have the covers off. I tried getting ahold of Micah at Mud Buddy but he was off today. Im sure somone on here know exactly what they should be and could help Thanks again

between .004 to .006

How long has the boat sat? Try some fresh fuel in it.

Someone a few weeks ago posted a video about adjusting valves... Check YouTube or do a search on here.

It ahs only sat for maybe a month without running I put Stabil in when the season ended and put fresh gas in when I went to start it. It seems like It does it when I accelerate and then when it just sits their and Idles. I can really here it when Im at wide open now. I went out and ran it for about 10 min once the motor and exhaust got hot I didnt here it at wide open but then when I decelerated back to idle it was popping again. I dont remeber ever hearing it until I put the carb and exhaust kit on. Thats why im wondering if its one of those things. I cant believe it would be the timing because other then this pop noise im hearing it runs great starts right up and Im getting about 4250rpms Wide open in deep water

Do you have dual exhaust? Can you tell which cylinder is making the noise? Start by pin pointing which side is doing it.

You sure its not a broken baffle in the exhaust?

Take the muffler off and shake it. if it jingles you have some broken stuff in there.

Ok guys took the exhaust of and their is deffinetly somthing loose I can hear it rattle and shake around in their cant get it to come out so must be somthing that came loose or broke. I tried to pin point where its coming from sounds it seems loke direcctly out the back of the muffler. Are they pretty good about takin care of the exhaust if its broke?

The broken baffle might just be a coincidence.

If'n its -10 your fuel isnt fully atomizing causing it to "Hiccup" or "pop" When its this cold you really have to let it warm up for a loooooooong time. Get the Exhaust fixed for sure , then try to run it again. If its still popin, try to find a heated shop or garage. Then once its up to temp run it to see if it still does it.

give it an asprin before performing surgery.

No, I've the stocker and the aftermarket exhaust with the mikuni. No problamo

Ran the boat last night it was very cold but the motor ran great with the old exhaust on. I really miss the sound of the BPS even after one day of running it. Thanks again for all the help the BPS gose back tomorrow for surgery hope to have it back on soon