huskyohilux Posted December 11, 2007 Report Share Posted December 11, 2007 I run 403cc duncan? (or maybe I don't, I haven't confirmed that yet) with pro curcuit exhaust and dual 35 mm Keihin PWK:s The needle clips are in top notch --> as lean as possible but still the plugs are dripping fuel after a good run, although it runs OK I use most mid range power so I rule out pilot (35) and main (175) I give it as much air as I can --> pro design filter and no air box lid Can it be that the carbs are too big for my engine? Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted December 11, 2007 Report Share Posted December 11, 2007 I run 403cc duncan? (or maybe I don't, I haven't confirmed that yet) with pro curcuit exhaust and dual 35 mm Keihin PWK:sThe needle clips are in top notch --> as lean as possible but still the plugs are dripping fuel after a good run, although it runs OK I use most mid range power so I rule out pilot (35) and main (175) I give it as much air as I can --> pro design filter and no air box lid Can it be that the carbs are too big for my engine? What needle are you running? Main jets seem a big to me. Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted December 11, 2007 Report Share Posted December 11, 2007 I agree, main seems too big, and if the plugs are wet, then it confirms you got too much gas flowin'...don't necessarily think your carbs are too much, just too big of a main jet. I'd try a 165 and see how it does Quote Link to comment Share on other sites More sharing options...
huskyohilux Posted December 11, 2007 Author Report Share Posted December 11, 2007 (edited) I run 403cc duncan? (or maybe I don't, I haven't confirmed that yet) with pro curcuit exhaust and dual 35 mm Keihin PWK:sThe needle clips are in top notch --> as lean as possible but still the plugs are dripping fuel after a good run, although it runs OK I use most mid range power so I rule out pilot (35) and main (175) I give it as much air as I can --> pro design filter and no air box lid Can it be that the carbs are too big for my engine? Needles are DEK Sorry got the jet sizes wrong... current setup is 170 mains and 48 pilots Edited December 11, 2007 by huskyohilux Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted December 11, 2007 Report Share Posted December 11, 2007 Needles are DEKSorry got the jet sizes wrong... current setup is 170 mains and 48 pilots Try Dropping the main down. My 400cc drag motors end up at 158 to 160 at sea level with that needle. Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted December 11, 2007 Report Share Posted December 11, 2007 In that case drop your mains and your pilots, I think the 48 is a little too big, probably could use a 45 for it.. I agree w/ KEV on the main, my buddy's 400 (done by Patriot racing) has 35mm carbs, pod filters, and is running 165 mains, but is also running drag pipes. 158/160 should be real close Quote Link to comment Share on other sites More sharing options...
jayzx10r Posted December 12, 2007 Report Share Posted December 12, 2007 (edited) I use most mid range power so I rule out pilot (35) and main (175) You have to remember that jetting is relative to throttle position and "power band" is relative to RPM. Check the Keihin Tuning/Jetting Guide for jet overlap: http://www.keihin-us.com/am/_media/pdf/slide_valve.pdf The 35mm PWKs came originally with a 160 main, DGK needle, and 68 pilot. So you are 10 larger on your main and 20 smaller on your pilot than it was originally. Unless you are running the 35mm Air Strikers... Then it is a 160, DEK, and a 48. If that's the case...it's just running fat!! Keihin's are typically pretty rich to start. I've never seen anyone need to go larger than the supplied jets...only smaller, so your main is a primary suspect. As a reference, my 33PWKs came with a 165 main and I'm down to 150 now on the main and went from the 52 to a 48 on the pilot...and I'm still running rich. I'd think your first step would be to determine which carbs you have. The standard 35s will have "70R" on the carb body facing out to the side, on the flange just above the float bowl. The Air Strikers will have "S65" engraved there instead. Most people start jetting in descending order...starting with the main, then the needle, then the pilot, then air screws. Everyone's Banshee's seem to want something different though... :wink: Here is the carb ID. Click to see the detail. Hope this helps... Jay. Edited December 12, 2007 by jayzx750 Quote Link to comment Share on other sites More sharing options...
huskyohilux Posted December 12, 2007 Author Report Share Posted December 12, 2007 You have to remember that jetting is relative to throttle position and "power band" is relative to RPM. Check the Keihin Tuning/Jetting Guide for jet overlap: http://www.keihin-us.com/am/_media/pdf/slide_valve.pdf The 35mm PWKs came originally with a 160 main, DGK needle, and 68 pilot. So you are 10 larger on your main and 20 smaller on your pilot than it was originally. Unless you are running the 35mm Air Strikers... Then it is a 160, DEK, and a 48. If that's the case...it's just running fat!! Keihin's are typically pretty rich to start. I've never seen anyone need to go larger than the supplied jets...only smaller, so your main is a primary suspect. As a reference, my 33PWKs came with a 165 main and I'm down to 150 now on the main and went from the 52 to a 48 on the pilot...and I'm still running rich. I'd think your first step would be to determine which carbs you have. The standard 35s will have "70R" on the carb body facing out to the side, on the flange just above the float bowl. The Air Strikers will have "S65" engraved there instead. Most people start jetting in descending order...starting with the main, then the needle, then the pilot, then air screws. Everyone's Banshee's seem to want something different though... :wink: Here is the carb ID. Click to see the detail. Hope this helps... Jay. Markings on the side are S65A2 0DA so they are air strikers. What's the difference between them and std? I just ordered 160 mains, so I'll try that and clip down the needle to middle again. Quote Link to comment Share on other sites More sharing options...
jayzx10r Posted December 12, 2007 Report Share Posted December 12, 2007 (edited) Markings on the side are S65A2 0DA so they are air strikers.What's the difference between them and std? I just ordered 160 mains, so I'll try that and clip down the needle to middle again. Here is a quote from the Keihin Website describing their PWK series carbs...the last 2 sentences pertain to the Air Striker enhancement over the standard PWK model: "The motocross world knows PWK. Keihin PWK carburetors is the dominant carb on the factory motocross machines. Because of their great performance they come stock on a lot of the leading brand bikes. With these features you can take advantage of Keihin's superior performance. Chromed semi-flat (D) throttle valve for excellent response and more flow at high RPM. Throttle bores sized to give maximum power. Easy jetting with jetting parts available. Quad Vents: Eliminates post jump bog-down from fuel plugged vent passages PWK Air Strikers: Directs air to main nozzle for improved signal and throttle response." -------------------------------------------------------------------------------------------------------------------------- I have zero experience with these carbs but their concept of operation sounds good. I'm not a carb guru nor do I claim all my info is written in stone...but it works for me. That being said... You asked if these carbs are too big for your engine. Everyone has a point of view on this question because it is kind of subjective and balances out a lot of variables. First...It would be good to find out what size your motor is and what mods have been done to it because if it is a 400+cc ported engine, these carbs could be a good choice...but it depends on what your type of riding is, what engine performance mods you have, and what your altitude is. For instance, if you are running a pretty modified engine somewhere near sea level generally at a higher RPM and at a mostly open throttle position...these carbs are a good choice. An engine is just an air pump, so if you are moving a lot of air, you can run a larger carb. Think duning or drag racing. If your motor is stock displacement, mildly ported, has an exhaust that prefers lower RPM, are at a higher altitude, or are usually riding at a lower RPM trying to grunt around the trails...you'd be far happier with a smaller carb setup for the low end response you need. Less air across the venturi and jets hinder fuel atomization so a smaller carb gives the velocity it needs to mix more efficiently. A lot of low end performance is given up with the use of the larger 33+mm carbs on not-so-modified motors so these are generally used by people that are at WOT (Wide Open Throttle) a lot...like drag racers and duners. If we only had Power Valves.... Read the pinned carb performance notes at the top of this forum from SREDISH. He is a pretty knowledgeable guy about this jetting/exhaust thing and he has helped me out in the past. If you are "dripping fuel"...you probably are going to need more than a 10 drop on the main... A note on buying jets...they can get expensive!! I went to the local small shop near my home and borrowed 5 sets of jets...and returned 4 of them back to them--along with some beer!! It isn't like you will ever need the jets you buy, try, and will never use again... :beer: Everyone likes beer!! :beer: Edited December 12, 2007 by jayzx750 Quote Link to comment Share on other sites More sharing options...
huskyohilux Posted December 13, 2007 Author Report Share Posted December 13, 2007 Here is a quote from the Keihin Website describing their PWK series carbs...the last 2 sentences pertain to the Air Striker enhancement over the standard PWK model: "The motocross world knows PWK. Keihin PWK carburetors is the dominant carb on the factory motocross machines. Because of their great performance they come stock on a lot of the leading brand bikes. With these features you can take advantage of Keihin's superior performance. Chromed semi-flat (D) throttle valve for excellent response and more flow at high RPM. Throttle bores sized to give maximum power. Easy jetting with jetting parts available. Quad Vents: Eliminates post jump bog-down from fuel plugged vent passages PWK Air Strikers: Directs air to main nozzle for improved signal and throttle response." -------------------------------------------------------------------------------------------------------------------------- I have zero experience with these carbs but their concept of operation sounds good. I'm not a carb guru nor do I claim all my info is written in stone...but it works for me. That being said... You asked if these carbs are too big for your engine. Everyone has a point of view on this question because it is kind of subjective and balances out a lot of variables. First...It would be good to find out what size your motor is and what mods have been done to it because if it is a 400+cc ported engine, these carbs could be a good choice...but it depends on what your type of riding is, what engine performance mods you have, and what your altitude is. For instance, if you are running a pretty modified engine somewhere near sea level generally at a higher RPM and at a mostly open throttle position...these carbs are a good choice. An engine is just an air pump, so if you are moving a lot of air, you can run a larger carb. Think duning or drag racing. If your motor is stock displacement, mildly ported, has an exhaust that prefers lower RPM, are at a higher altitude, or are usually riding at a lower RPM trying to grunt around the trails...you'd be far happier with a smaller carb setup for the low end response you need. Less air across the venturi and jets hinder fuel atomization so a smaller carb gives the velocity it needs to mix more efficiently. A lot of low end performance is given up with the use of the larger 33+mm carbs on not-so-modified motors so these are generally used by people that are at WOT (Wide Open Throttle) a lot...like drag racers and duners. If we only had Power Valves.... Read the pinned carb performance notes at the top of this forum from SREDISH. He is a pretty knowledgeable guy about this jetting/exhaust thing and he has helped me out in the past. If you are "dripping fuel"...you probably are going to need more than a 10 drop on the main... A note on buying jets...they can get expensive!! I went to the local small shop near my home and borrowed 5 sets of jets...and returned 4 of them back to them--along with some beer!! It isn't like you will ever need the jets you buy, try, and will never use again... :beer: Everyone likes beer!! :beer: I haven't confirmed my engine displacement yet. The guy I baught it from said duncan 403cc and since he already put almost $10,000 (probably cheaper in the US then here in Sweden) on other mods such as roll design swing, elka shocks, keihins, roll design front end, cool head, durablue rear axle etc, etc. There was no reason for me to believe that he wasn't telling the truth. But as soon as I need to remove the head I'll take measurements to make sure. He rode national competitions with it and the way I ride is not a lot of WOT. So that's why I need to change jetting so I'll get some more middle range. The 35 mms are probably more than I need...But the bike runs OK for my needs aswell now even though the plugs aren't getting that light brown surface I'm looking for. I'll try smaller mains and see how it does otherwise maybe I'll look for something smaller on E-bay e.g. 28s or 33s Thanks for the input guys! Quote Link to comment Share on other sites More sharing options...
BaNsHeeJuNkEy Posted January 13, 2008 Report Share Posted January 13, 2008 hey your running the same carbs as me and mine are on a stock motor. i am at sea lever and right now my pilot is 42 and my mains are 148 cgl needle on 3rd clip and still a rich. i got to lean mine out more still. for a rough idea. i would keep tryn to get them to work. but if you are on stock just and stock head with out port job you are way to rich. i been fighting with mine for the past month of being to rich and going leaner little by little. Quote Link to comment Share on other sites More sharing options...
huskyohilux Posted January 16, 2008 Author Report Share Posted January 16, 2008 i put them on with a bunch of other thing not sure what i am going to gain for sure but should get a lot of top end more power all around and more response. and as fare as fmf or procircets don't realy think there is much of a difference between the two. i am thinking i am going to end up around a 142 or 145 main i think not sure. my pilot seems very responsive tho. but i will keep it up let me know how you make out with them. Got I tip from a swedish shop that my problems could be due to worn reeds. And that it should run fine with 160 main or even 170 (as I've run on and beeing rich on all the time), for some reason the air here is different or someting...? So I'll give my keihins one last chance with Boyesen pro series (retail: $150 here in Sweden!!!) and a pair of reed spacer for clutch lever clearance. I think I'll put in the 160 mains, 45 pilot and clip the needles in the middle ...Praying for some real banshee action!!! Any thought regarding worn reeds and too much gas in the combustion? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.