dwbchevy Posted February 18, 2007 Report Share Posted February 18, 2007 I've built a 421cc engine, non power valve, 21cc domes, 35PWK's, CPI pipes. I'm at 3200 ft. temp's 50-90 degrees. Jetting is killing me. The engine idles great, pulls strong on top, but if your looking for anything off idle to 3/4 throttle is bogs, spits, sputters until it cleans out. I started with 53 pilot, 160 main. Very rich. I'm now at 35 pilot, 145main, and every where in between, much better. Plug is slightly tan, heat range looks good. Help from anyone would be greatly appreicated. Quote Link to comment Share on other sites More sharing options...
moneybags Posted February 18, 2007 Report Share Posted February 18, 2007 I have a 421 cub with 35 PWK and more. (look in my sig) I am at sea level with jetting at 155 main and 52 poilet. Middle clip on needle Air screws at 1 1-2 turns out. Did you ajust your air screws? It takes a minet to take affect. Do a plug chop to judge your jetting. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted February 18, 2007 Report Share Posted February 18, 2007 What needle are you guys running in your 35's? Quote Link to comment Share on other sites More sharing options...
dwbchevy Posted February 18, 2007 Author Report Share Posted February 18, 2007 I have a 421 cub with 35 PWK and more. (look in my sig) I am at sea level with jetting at 155 main and 52 poilet. Middle clip on needle Air screws at 1 1-2 turns out. Did you ajust your air screws? It takes a minet to take affect. Do a plug chop to judge your jetting. I've adjusted air screws many times. Right now there at 1 turn out. Tell me about a plug chop, never heard of that one. Quote Link to comment Share on other sites More sharing options...
moneybags Posted February 19, 2007 Report Share Posted February 19, 2007 http://www.dfn.com/benkaren/plugchop.html I though my computer was going to melt when I typed plugchop into the search box. It took forever Quote Link to comment Share on other sites More sharing options...
dwbchevy Posted February 19, 2007 Author Report Share Posted February 19, 2007 What needle are you guys running in your 35's? CEL Quote Link to comment Share on other sites More sharing options...
Banchetta Posted February 22, 2007 Report Share Posted February 22, 2007 You have to be wayyy too lean w/ 145's....I run a 162 main, 42 pilot, DEK needle on the 3rd clip w/ my 4 mil......That hesitation you have has a lot to do w/ the CPI pipes. They are a high rev pipe and don't make any power down low...DO NOT adjust your mains to this...Check your plugs or feel how hard it pulls on top to check the mains....try raising or lowering the clips on the needles, this will change the richness at 1/4-3/4 throttle. I would also try a set of DEK needles...it'll have a richer taper on the initial throttle hit coming from the pilot to the 3/4 throttle....Sputtering like the choke is on is a sign of richness, hesitation and holding back is a sign of leanness...Your pilot will have an effect on throttle response as well as idle and starting...A lean pilot will require the choke even on hot days. A rich pilot will start up even at 40 degrees out w/ no choke but will start harder once warmed up...and you'll need to crack the throttle when starting. Quote Link to comment Share on other sites More sharing options...
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