TTR125 Exhaust Cap

I got a significant power increase out of my Son's '03 Yamaha TTR125L by just removing the screen between the airfilter and carb, and replacing the stock spark arrestor with a $20 exhaust endcap from Lee Lohman (

Power felt like it went up about 20% without re-jetting, or cutting on the airbox. TTR revs much easier and according to my son sounds cool.

Anybody know where to get a rear fender cheap. It seems the increase in power resulted in unexpected wheelie and cracked rear fender. :)

Original Yam fender costs only about $30. I know cuz I had to buy one too.

so the screen is right between the filter and the wall of the air box? is the screen easy to take out?

Just remove the three screws from the left side of the box, and it slides right out.

Whats the screen in there for anyways?

To stop the aircleaner catching on fire if the engine backfires. Most 4 stroke bikes have them. I usely remove them and havent lost a bike yet. But ..... Sniff Sniff.... HMMMMMM is that something burning................... :)

are you sure that the screen is not in the RIGHT side of the air box that the boot hooks into? :)

I don't think the purpose is for backfire protection. We also use these screens between the air bonnet and carb on the machines we build. They make the air flow from the airbox more uniform rather than a vortex. Nonetheless, it is a restriction and removing it may improve performance. Manufacturers are concerned about efficiency and emissions whereas we are not. I don't think it would stop a spark or flame from a back fire. I've taken mine out of my DRZ but haven't been able to evaluate it yet.

Nope, I mean the left :) side, the airbox has 3 screws on that side, remove cover, slide out screen.

is it that powerful...It seems the increase in power resulted in unexpected wheelie and cracked rear fender.

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