On the numerous Honda XR's and KLR600/650's that I had where I ran the screen initially while having exhaust and other mods, I had to increase the main jet size by one. After removing the screen with no other modification, I had discernible detonation from about mid-throttle to WOT when rolling the throttle on. A larger main removed that. I've never done any dyno testing, but my WOT performance was improved. One of those KLRs did an actual GPS 104 mph with the screen removed, aftermarket muffler, and airbox opened up a bit.

While we can discuss seat-of-the-pants and dyno issues, the bottom line to me is that removing the screen does absolutely no harm. Your bike will not burst into flame.

 

I removed my back fire screen from my crf250l last night...its real easy since its actually part of the air filter....I felt a negative affect....bike was less responsive....full fmf exhaust got a little quieter, but "raspy"..putting it back in today.

 

That's an FI bike, right? While I'd think the stock fuel map might be capable of handling the modification, perhaps it's not. In fact I'd think it might not based on your results. Just like the necessity of rejetting a carb after engine, exhaust, and intake mods, the Honda may require an aftermarket programmer like many other FI bikes with such mods to run properly.

 

I actually have an EJK fuel programmer...i didnt change any settings after...going to put the screen back in and try a 13t....hoping to gain the ability to push better in 5th and 6th gear

 

Why not try a tweak to the fuel map with your programmer?

 

*Unless* it's a bike equipped with Amal carbs, in which case I can assure you from bitter experience, that there is a high probability that the bike *will* burst into flame.

 

Oh...I didn't realize you were riding museum pieces out there, gc.

I always thought it ironic that many bikes that came with what may have been one of the most horrid carbs also came with the most horrid electrics...Lucas. Let's see...what's the formula we all know?...spark, fuel, and air? Well, nothing like an Amal, Lucas, and air to fire up your bike...literally.

 

Well, they were partly correct back then, they just hadn't yet figured out that those 3 things are supposed to be *inside* the cylinder!

 

I dont understand it lol