KDXRIDER.NET

I bought this pipe and it says that it's a one size fits all sort if thing. How would I determing what I should or shouldn't put it on? I'm selling my 83 KDX250, which is what I have it on but I also have a 91 KDX200 that will need a pipe. How can I tell if it's okay to put it on that? All 3 of my bikes KDX200, KDX250 and RM250 all have new wiseco pistons and I don't want to mess anything up.
Here's a pic of the muffler in question.
Thanks

For starters, that is not a "pipe"

Silencer/spark arrestor but not a pipe

Not gonna mess anything up running that

yea, what Wib said. That's a silencer that has a spark arrester built in. It bolts up to your pipe, AKA exhaust pipe, expansion chamber. If it will bolt up to a pipe on any of your bikes, then it's good to go! It might need repacking if it's all spooged up inside though.

I did say muffler at the very end!
So what about rejetting? Can I just keep the stock jetting with this slip-on?
Thanks

'Stock jetting' is hardly ever 'right' for anything.

The answer to your question is, 'Yes.' You can keep the stock jetting. The bike will run as well as it did, which is to say not nearly as well as it should.

The next question should not be, 'What jets should I use?' Jetting a bike is more of a process than it is a list of jets to use. Learn how to jet a bike and that knowledge will serve you well for years to come and bikes to come.