4mil banshee2000 Posted June 7, 2014 Report Share Posted June 7, 2014 Hay guys I need some help I've got a 4mil banshee that I just built. Need jetting help. Its got a vitos 4mil long rod ,wiseco795 pistons .40 over MX hardcore port by HJR Noss head with 21cc stroker domes Pro circuit pipe Air box no lid k&n with pro flow plate Boyesen pro reeds stock cages +4 timing Stock carbs with TORS removed 80-90 degrees High humidity about 1300ft above sea level I talked to Kevin at HJR and he told me to start out 330 main and stock needle in 3rd clip. So I did a couple heat cycles on those jets and took it for a spin. Now ive never owned a banshee it was blown when I got it but ive road several banshees and it felt like it was rich and bogging. I started going down on the jets well now im at a 260 and its a lot better but from what ive read it sounds like my jets are really small for a 4mil. My dad has one stock stroked with a drag port and he's running 270s. What do you guys think? Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted June 8, 2014 Report Share Posted June 8, 2014 Have you done a plug chop? (or read if you know what you're doing) Are they genuine Mikuni jets, or AM bullshit jet kits? What size pilot jet? Too small Pilot will cause bogging. Difference in stroke would have little to do with jetting. What plugs and timing? Quote Link to comment Share on other sites More sharing options...
4mil banshee2000 Posted June 8, 2014 Author Report Share Posted June 8, 2014 I haven't done a plug chop because it doesn't have a clean rev. Im running 27.5 pilots I don't have any mikuni jets. I got a jet kit. It was a rip off but i got some pro x jets to fill in the gaps. I didn't know that it mattered. I started out with 330 pro x jets and road it around and it felt like it was bogging but i didn't know for sure. So i tried the choke trick and it made it worse. So i started going down on the jets one at a time and it got better and better but now im at 260 and It feels really close. Everytime I pull the plugs out they are shiny and wet with oil on the tips. Quote Link to comment Share on other sites More sharing options...
Zillaguy Posted June 8, 2014 Report Share Posted June 8, 2014 try 340-350 on the main and 30-35 on the pilot... Needles middle clip, pilot air screws 1.5 turns out. Quote Link to comment Share on other sites More sharing options...
Frankthetank Posted June 8, 2014 Report Share Posted June 8, 2014 I've got a stock cylinder 4mil with stock carbs and a dune port. I am running 400 mains, 32.5 pilot and needle of the 3rd clip. air screw at 2.5 turns out at 85 degs. If it was me I would bump up your pilot jet a little. I don't think that your main will be as big as mine but if should be somewhat close. My setup is a little more aggressive than yours so jetting will be different. If possible I would get in touch with a shop that has a dyno and talk to them or go see them. That will help a lot. Good luck. Quote Link to comment Share on other sites More sharing options...
bluebanshee98 Posted June 9, 2014 Report Share Posted June 9, 2014 I've got a stock cylinder 4mil with stock carbs and a dune port. I am running 400 mains, 32.5 pilot and needle of the 3rd clip. air screw at 2.5 turns out at 85 degs. If it was me I would bump up your pilot jet a little. I don't think that your main will be as big as mine but if should be somewhat close. My setup is a little more aggressive than yours so jetting will be different. If possible I would get in touch with a shop that has a dyno and talk to them or go see them. That will help a lot. Good luck.Are you sure you don't have any air leaks? Have you done a leakdown test? Those are huge mains for that motor IMO even if it does have a "real Aggressive" porting. Quote Link to comment Share on other sites More sharing options...
Frankthetank Posted June 10, 2014 Report Share Posted June 10, 2014 I believe it was leak tested. It was a redline build and Cam told me that it was. I dynod it around 15 times to get the jetting right. The air/fuel numbers looked good along with the other readings. Quote Link to comment Share on other sites More sharing options...
Strm Trpr Posted June 10, 2014 Report Share Posted June 10, 2014 Are you sure you don't have any air leaks? Have you done a leakdown test? Those are huge mains for that motor IMO even if it does have a "real Aggressive" porting. The pilot is a little big due to his airscrews being turned out 2.5 times which should help reduce the mains from 400 down. I've seen 4mil stk cyl dune ports running 330 mains with VF3's and pods on stk carbs. Frankthetank, what reeds and intakes are you running? Pods? Elevation? Plug Chop? OP, try 30 pilots and 340 mains needle clip middle groove 2 turns out on airscrews. Are the carbs idling perfect at 1500rpm and sync'd with a FAST Sync Tool? Is part throttle sync'd also? Meaning do the carb slides lift off at the same time and does the vac reading match? Only way to tune these bitches is with a cheap ebay tach and a FAST Sync Tool, period... Quote Link to comment Share on other sites More sharing options...
Strm Trpr Posted June 10, 2014 Report Share Posted June 10, 2014 OP, do a proper plug chop. http://www.dfn.com/agservices/jetfaq.html Quote Link to comment Share on other sites More sharing options...
Frankthetank Posted June 10, 2014 Report Share Posted June 10, 2014 I'm not looking to drag attention away from the original post, but I have a stock cylinder, stock carbs, .20 over, vf3, 4 mil, redline dune port, cpi inframe pipes, k&n pods, and after running the lower jetting size the air/fuel ratio was very high. I tried each combo of jets and the clip position to get the air/fuel and hp where I wanted it and still have a reliable motor. Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted June 13, 2014 Report Share Posted June 13, 2014 I had the same jetting, and the bog went away when I got down to about a 1/2 turn out on the needle. That also means the pilot needs to be bigger. Quote Link to comment Share on other sites More sharing options...
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