The UniFilter is also wide open.  No obstructions in here.

The Uni filter works very well at filtering, is easier to install and fit in tight spaces due to its flexibility.  And it’s cheaper by comparison.
I’ve used this filter for years on my Savage.

Thanks very much for the picture of your exhaust.  I am gonna stick my neck out and say that your exhaust is not a hi-flow system.  Any sort of baffle inserted in that straight pipe most likely plugs things up.  But I've been wrong more than a time or two.

Can you remove the baffle and post several pictures so we can see all the features of the baffle (length, holes, flow path, etc.).

I suspect you have a stock header pipe with an extension attached.  The stock header only has a 1.3" interior cross-section, it's pretty restrictive.  The extension is most likely a 2" pipe to match the O.D. of the stock header.  So, there isn't much volume to store spent gas while the baffle allows the pressure to bleed off.

While you have the baffle removed, it's time for another quick & dirty test.

Red Alert!  Caution!  Danger!  Do not run the guts out of it with the air filter off and the baffle removed.  A few simple WOT runs in 2nd gear will suffice.  Do not go WOT in top gear and take it up to high speed.

With the air filter and baffle removed, run it up in first & second gear.  See if the high-rpm stutter is gone.  If it starts backfiring at high rpm, stop the test.  Don't run it for a long time in this configuration; you will hurt it.  Just run the test once or twice to determine if things improve.

Let us know how it goes.

Thanks Mike.
The baffle is welded at 2 points. I'll have to drill it out. I have opened the exhaust port quite a bit at the head. The exhaust was purchased from bluecollar bobbers before I got the bike.

Would running the bike with the baffles removed full time cause issues ? Or do you just mean not to do it long in combination with the lack of the filter.
I have a large automotive cone filter fitted now.

I am pretty sure your air filter is blocking that port, buy the one im posting, it’ll fit without trimming the stock airbox

"The baffle is welded at 2 points. I'll have to drill it out. "

Please don't do that.  It's just a quick & dirty test.  I reviewed the vids on Blue Collar Bobbers website.  The exhaust vid is second to last.  That system uses the stock header with an extension to give it the drag pipe look.  The extension is just glued on with silicone.  All you have to do is pull the extension off and you accomplish the same thing as removing the baffle.  It's not gonna run nice but it should be able to pull to max revs without stuttering and/or blubbering.  Have you viewed that video?  If not, you should view it.


"Would running the bike with the baffles removed full time cause issues ?"

Generally speaking, running with an open header is not ideal.  If you have a cam with any overlap and TDC lift (i.e. the DR650 cam), an open header causes lots of exhaust reversion, so the carb is almost impossible to dial in at part throttle.  It will work good at WOT high rpm, but it will cruise lousy.  It is also anti-social and obnoxious.  Don't run it like that.  Just a test is OK; permanent not OK.  Runs bad, sounds bad, is bad.

The stuttering, blubbering, misfiring & backfiring can be caused by overly rich or lean mixtures.  In general, overly rich won't hurt it....but overly lean is another story.  I can't say for sure if you are rich or lean, but running without the air filter, and with an open exhaust, and with more displacement, and more compression, and with a hotter cam should make it lean if you have a stock main jet (#155 for early model LS).  As mentioned before, that assumes no one has drilled out that main jet.  It also assumes your main air bleed is correct and not plugged.  It also assumes your needle and needle jet are stock and the needle height is within acceptable limits (i.e. not pulling out of the needle jet).  Generally, rich mixtures cause blubbering at WOT (your vid sounded that way to me, but it's a vid); lean mixtures cause high rpm backfiring, popping out the carb, and misfiring.   Rich dull sound, lean sharp crackle.

How is your spark plug lookin now?  Is it still black as coal?  Rich mixture, black plug.  Lean mixture, white plug.

Good clear pictures of all this stuff along with data regarding the markings on each component would be most helpful.  A nice clear shot of your main airbleed illuminated would be nice.  If you take that extension pipe off your exhaust, take photos with the baffle illuminated so we can see what that looks like.  Pull the spark plug and post a photo of it now after you got it runnin better.  It's very difficult to help you without photos.

I had a problem once and it turned out to be float height.

Here is a picture of the spark plug after about  90kms with the velocity stack.