300EX Exhaust/Muffler swap back to Stock

[James96GT]

Hi, I just purchased a used 2000 Honda 300EX. The previous owner installed a K&N Filter w/Pre-Filter, HMF Slip On and a "Jet Kit" don't know the sizes. The HMF is too loud for my neighborhood. I have a Quiet Core on the way but wanted to know if I put the Stock exhaust back on what will the impact to the "Jet Kit". Can I leave it in? If I do will I need to make adjustments? What problems could I see?

Thanks!

[300exOH]

You will most likely be running too rich with the stock exhaust which may foul plugs and it may bog out a bit too. You would be better off rejetting back to stock while you run the stock pipe.

[James96GT]

Thanks. At least it will be rich and not lean... Re-Jetting isn't a huge deal but I have never done it and was hoping to avoid the work....

[300exOH]

Rich is definitely better than lean. Once you get the hang of re-jetting it's not that bad at all. I read quite a bit on the subject before trying it for the first time and I've not had a problem with it since. It can be tedious though. There is a write up on jetting in the "articles" section at the top of every page that should help if you want to give it a shot. You may need to rejet for the quiet core anyhow.

You can try it with the jetting as-is and maybe take the airbox lid off to give it a little more air to lean the mixture slightly with the stock pipe in place. With an after market air filter your jetting may not be too far off then.

[James96GT]

Thanks for the help. I just got it with the mods and just am not familiar with them. I can turn a wrench and trust stock stuff.

It already has the filter box lid off. I suspect it's running lean as is, will check tonight (bought the socket for plug today).

[300exOH]

I would give it a try then and see how it acts with the stock pipe. If it bogs you will probably have to re-jet but if not it should be fine until you get your quiet core. HMF should be able to get you in the ballpark with the jetting for the quiet core. I would pick up another crush gasket for the pipe before you bolt it on to eliminate the possibility of any exhaust leak.(which would cause it to run lean as well) I think they are only a couple $$ even at the dealer.

[doughwarrior]

I have a complete stock exhaust if needed.