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CB400f with K&N Pods Filters - what carb jetting are you using ?
400 Cafe Racer:
--- Quote from: Norniron on September 28, 2021, 02:54:17 AM ---Hi Dennis,there are flat spots,but thats pods for you.
Plug colour is fine.
Obviously best set up is stock
--- End quote ---
Hi Norniron,
Which needle notch did you find worked best on your set up please.
Cheers
Dennis
Norniron:
--- Quote from: 400 Cafe Racer on September 29, 2021, 06:06:47 PM ---
--- Quote from: Norniron on September 28, 2021, 02:54:17 AM ---Hi Dennis,there are flat spots,but thats pods for you.
Plug colour is fine.
Obviously best set up is stock
--- End quote ---
Hi Norniron,
Which needle notch did you find worked best on your set up please.
Cheers
Hi Dennis,its still in the middle notch
Dennis
--- End quote ---
400 Cafe Racer:
Hi Norniron,
Thanks for your reply. I am currently doing some tests on different positions and different jet settings using the A/F meter (Air Fuel ratio measurement) under live running conditions.
As you can appreciate, every change of needle position or jet means, seat, tank and carbs all have to be removed and carbs stripped to make the changes. Then on refitting etc carbs all need to be re-syncronised and adjusted. Not a quick job , but it is worth it.
1. I initially tried the carbs as the PO had them set, just checking and correcting float levels and correcing the dynamic timing when I rebuilt the engine. The outcome was reasonable torque and power, but mixture generally smelling too rich, some smelling in the oil and readings of about 9.8 :1 and 10.2 :1 throughout the range and some plug fouling occasionally. Clearly far too rich.
2. Next test. Change main jet from 95 to 85. Result was good torque and power, with 12 :1 AFR on full throttle and between 10.9 to 11.2 :1 on 1/4 to 3/4 throttle. Still a tad too rich.
3. Previously set on one slot lower/richer than normal, I decided to try the middle notch setting and in testing found it slightly erratic reading between 13.1 :1 and 14 :1 on all openings between 1/4 and 3/4 throttle. I found the engine a little less smooth on acceleration, with a drop in torque and power, plus an increase of approx 10 degrees in engine running/oil temperature. Not happy with this setting, but made a valuable discovery while setting the needles lower. I think the erratic reading and less smoothness were pre-ignition, which also affected engine temperature.
I started with No1 carb going to the centre notch, then 2 &3 BUT when I got to No4 I had slight difficulty getting the assembly apart to gain access to the needle.
The reason was that the needle and clip were fitted ABOVE the clamping plate, instead of beneath it in the recessed portion for the clip.
This meant that this carb needle was the equivalent of about 3 to 4 notches too rich.
4. The next test will be with the needles 1 notch lower (richer) than standard where the best torque and power were found, as on test 2. With the needle in No4 carb now seated correctly this should address the previous slight overall richness. Ideally I am looking to set up for between 11.8 and 12.7 where the best power with cooler running should be. This will not give best consumption but will be kinder on the pistons.
Due to working on front forks it will be a few days before I re-test.
Cheers ;)
Dennis
Laverdaroo:
Super interesting that, keep us posted on next setting results please. I have a Steeldragon air box coming from the states and although not the same, its sill not a standard thing so any info gleaned from your posts is very useful, and potentially a good starting point for me.
400 Cafe Racer:
--- Quote from: Laverdaroo on November 22, 2021, 10:40:17 PM ---Super interesting that, keep us posted on next setting results please. I have a Steeldragon air box coming from the states and although not the same, its sill not a standard thing so any info gleaned from your posts is very useful, and potentially a good starting point for me.
--- End quote ---
Hi Laverdaroo,
Got around to doing the final Carb settings today.
Recap: K&N Pods. fitted to Standard Carbs.
New jetting to - Idle 40, with mixture screw 1.75 turns out on all Carbs.
Main jet 85
Needle position in slide Clip Lowered by one notch from middle, ie 1 notch richer
The results are giving AFRatio readings of between 11.7 and 12.4, which is just where I needed them to give best power, torque and cooler running.
I am well pleased after investing the time in the multiple "strip and reset" project on the carbs and these will remain my final settings.
I hope this post may prove helpful to other members.
Cheers ;) :)
Dennis
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