Ozrider (Les) Big Bore exhuast, 1st in world!

If cruising at 3500 or so and opening throttle fast the bike just goooooos. If opening fast at 4000-4500 or anywhere above it’s just plain rowdy and violent.

It’s not all the pipe, but some of it is.

The other items adding to the lower RPM torque are the 3D printed bellmouths, bored throttle bodies, and the decked head (compression).

The bored throttle bodies moved the torque peak(s), down about 500 RPM from where they were from back in March when I baselines my bike with this exhaust.

I put in my order for some new printed bell mouths last night and I took delivery of three stock intake rubbers.

Next trip to Nels is back to back comparison of the two options, we ran out of time this trip.

The lowered torque peak rpm by the throttle bodies means I can now run shorter bellmouths to spread the torque even wider and hopefully make a little more above 6500.
 
I'm sure glad I have a backup bike to ride, because I may be copying your mods to get better power too. The way it widened the torque curve is impressive. The way it hits at 4500 instead of 5500 would make rolling on at highway speeds more insane than it already is. Those poor kids on their liter bikes will drown from all of the tears in their helmets.
 
The biggest change came with the Throttle Bodies.

It's not a totally straight forward modification though.

There's some fiddling required with the linkage assembly, a couple of vacuum ports behind the primary throttle blades that are sealed with the stock bore will be cut open and need to be filled with epoxy, and of course, a re-tune is required.

Then there's the matter of blending the rubber joiner between the TB and the head, nothing a few minutes with a dremel cant fix, but its a circle to oval transition, so you need to be careful when doing it to preserve smooth transition.

I do think its worth the effort though for the highly built naturally aspirated bikes, and I wish I'd done it sooner.

Ill update the TB boring thread with more pics.

EDIT: Added pics to the TB thread to show what I mean:
Throttlebody Mods and Tune
 
Last edited:
Sounds really sweet bro; Enjoy and "Be Safe!
 
Steel said:
I hope it woks well. At least we know @Claviger will give us some honest numbers whether good or bad. Over the years in different forums I've seen people claim crazy numbers, but never seem to want to post a dyno sheet.

BTW, I like my springs
Click to expand...
Don’t tell sonny
 
Hey Rob quick question for ya, when you installed your headers did you install a new set of gaskets or does it need 2 sets, they’re calling for 6? Thanks
 
I use 1 per cylinder as intended. I do use a little copper rtv around the outer edge before clamping it all down. Just a precaution.

Let's pipes haven't leaked at the head at all, on and off 3 or 4 times with the same gaskets now.
 
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