decelarating popping

[hippy440]

when i let off the gas from wot it pops through the exhaust what jet do i need to change??

[400exRacerX]

You don't have to change any jets, I had the same exact problem and Gabe helped me out with it, everyone told me to change my pilot jet. But Gabe had the most knowledge and told me it was a exhuast leak and he was right, let me find the link to this thread it is way back in the archives of exriders.

[400exRacerX]

Here the link is I hope it helped you, http://www.exriders.com/ubb/Forum3/HTML/000352.html if you have any questions ask away.

Yup- you got an exhaust leak. probably around the head to pipe crush washers or at the pipe joint. IF you find that there is no leak than turn the mixture screw out 1/2 turn. 99.9% of the time fresh air is getting into the exhaust when you decelerate and ignites the unburned fuel to cause a backfire.:D

[400exRacerX]

Also sometimes with aftermarket exhuast systmes they tweak the head pipes, so they could be leaking at were the head pipe meets the silencer or at were the head pipe meets the engine. check it out.

I notice that when my machine is idling, there is a slight amount of exhaust fumes escaping out between the pipe(supertrappIDS2) and header. Mine also pops a bit when I let off the fuel. How should this be fixed. Also, is it going to hurt anything? Something else, when I start it up when it is cold, A bit of black liquid(unburned fuel, rich mixture at Idle?) drips out between the pipe and header where small amounts of air puff out. Maybe because of using the choke, and I also have the pilot screw turned out 1/2-3/4 out. It idles MUCH better when cold since I did that. I dont have to stay on the gas when it is cold like I used to. anyway, just wondering about the exhaust leak, and how to fix it. and the clamp is tight around the pipe and header. thanks.

[400exRacerX]

The reason why it is popping is because the unburnt fuel in the exhuast is mixing with fresh air and is combusting inside the exhuast system. This is very bad for the engine and should be taken care of as soon as possible. If not treated you will have some serious damage done to your exhuast valves.

[Tommy 17]

i have a question about a weird noise on my friends 4 stroke bikes. we have a cr450f and yz250f and yz426 and a ktm 520 and sometimes when they are hard on the gas ur hear this noise like they are poping and its sounds really funny is this what u guys are talkin about. they all have stock pipes.

[jjyo]

I just got a new e series pro meg last week for my '00 300ex. White bros says to reuse the gasket between the headpipe and stock muffler, but it was impossible to get out without screwing it up. I went ahead and tried to use it and I get lots of popping on deceleration, so I'm sure I've got a leak. What's the best gasket to use for this? Should I go get a new Honda OEM gasket or is there something else you guys use?
:confused:

[400exRacerX]

Yes, my friend has a 300ex with the pro meg and we called White Bros and they said to reuse the old one but it was immpossible to get out. So he went to the dealer and ordered a OEM gasket and it worked fine.

I was having the same problem when I got my bike back from my honda dealer. They left my pilot jet the same but went down on the size of my main jet. This was after they installed the K&N airfilter and new header and pipe. As soon as I got home I knew things were not right. I came to this site and plenty of people told me to up my main jet to a 160. I did this and the problem has been eliminated. Should I still be worried about a possible exhaust leak?

[Chef]

so they went down on the main jet after you installed freer flowing exhaust and air filter? dude, i think your shop needs to go back to mechanic school