ninjette.org - View Single Post - Another ex500 swap into a pregen ninja 250

Mauricemonge · July 31st, 2022, 10:01 PM

Oh boy, I’ve been down a 2 day adventure trying to tune with pod filters.

DannoXYZ I installed 6” of runner tube between the pod filters, but I don’t think it helped much. I’m still running them anyway, they probably help overall. I may take them off to see if there’s a difference.

Not to bore with the details of how I found the compromise of making it work. But I was struggling with a 1/3 throttle lean out around 5-6,500 rpm. It would lean out to 16.5 and get choppy.

I ended up using my ex250 needles with two shims underneath.
The carbs are from an LTD454 so the slides and spring are apparently different. The slide had already been drilled out to 3mm.
I used a 140 main jet, 40 pilot, 1.5 turns for the idle screw.

Seems to run great! A slight lean out (14.5 AFR) around 4000-5000 rpm between 1/3-1/2 throttle, but it corrects itself quickly. It backfires on deceleration a bit though, I blew up my muffler a week ago because of backfires. But I jb welded it back together.

Drag racing this Wednesday!

July 31st, 2022, 10:01 PM	#22
Mauricemonge ninjette.org member Name: Maurice Location: San Francisco Join Date: Sep 2018 Motorcycle(s): bastardized ninja 250 (think land speed record with a sidecar) soon to swap a 500 engine Posts: 34	Oh boy, I’ve been down a 2 day adventure trying to tune with pod filters. DannoXYZ I installed 6” of runner tube between the pod filters, but I don’t think it helped much. I’m still running them anyway, they probably help overall. I may take them off to see if there’s a difference. Not to bore with the details of how I found the compromise of making it work. But I was struggling with a 1/3 throttle lean out around 5-6,500 rpm. It would lean out to 16.5 and get choppy. I ended up using my ex250 needles with two shims underneath. The carbs are from an LTD454 so the slides and spring are apparently different. The slide had already been drilled out to 3mm. I used a 140 main jet, 40 pilot, 1.5 turns for the idle screw. Seems to run great! A slight lean out (14.5 AFR) around 4000-5000 rpm between 1/3-1/2 throttle, but it corrects itself quickly. It backfires on deceleration a bit though, I blew up my muffler a week ago because of backfires. But I jb welded it back together. Drag racing this Wednesday!