First and foremost a very big thank you to ZeroClient for all his help as I am going thru this process...
The new 35mm PWK I bought for the 350 seemed quite rich throughout the entire throttle range right from the start. Struggled to get it to idle especially. We had dropped from the original 48 pilot to a 42 which helped it but still very fat idle and it had a stumble right off idle. WOT (Wide Open Throttle) also seemed a little off but plug chop didn't look bad. We dropped from the 160 main it came with to a 155 which seemed to help but I wanted to really know what was going on so I bought the WB O2 setup a few days ago. Got it setup and began testing yesterday.
Making the sensor clamp work with the original pipe was a bit of a challenge. Some quality red neck engineering solved the issue. After some measuring and digging around, I figured out that a piece of left over top rail from a chain link fence was the perfect answer. lol... No really. The small end is a great fit in the factory silencer. I cut a 6" piece and tapped it in place.
IMG_9189 by TerryHatfield, on Flickr
IMG_9194 by TerryHatfield, on FlickrI wired power from the battery for the gauge and made simple bracket from a piece of aluminum angle to mount it on the right front cage down tube connection. Obviously this setup is only on the buggy for tuning so no need to do anything elaborate. I moved the GoPro mount to that down tube so I could record the readings even though trying to get decent video turned out to be more challenging that one would think it would have been.
IMG_9193 by TerryHatfield, on FlickrOriginal 35mm PWK setup. 48 pilot. 4.5 slide. DEK needle on position 3. 160 main.
After butt dyno/plug reading. 42 pilot. No change on needle or clip position. 155 main.
Once WB testing began we changed to a leaner 5.5 slide which helped the idle a lot but 1/4 and 1/2 throttle were still rich. ZeroClient convinced me to file and polish the original 4.5 slide to the dimensions of a 6.0 slide. I was a bit apprehensive but it turned out to be a pretty simple process. ZC also suggested moving the needle clp to position #4.
The slide after mods...
IMG_E9190 by TerryHatfield, on FlickrThis greatly improved the idle and completely fixed the off idle bog. 1/4 and 1/2 throttle performance is improved resulting in much more bottom end power. I didn't have any jets leaner than the 55 other than a 142. Gave that a try and it was too lean at WOT (Wide Open Throttle) as expected. I've ordered some leaner main jets and a richer needle from JetsRus. We'll resume testing once those parts arrive. I can't imagine doing this level of tuning without the WB. More to come...
