4stroker Posted September 9, 2007 Report Share Posted September 9, 2007 (edited) ok guys so i finally got the rz motor built and in the bansh, and spent the weekend trying to dial in the jetting. these are my mods: RZ top end, aggressive port job (massive boost ports) T5 pipes Vforce 3 reeds reed spacers between the reeds and pro design in take with boost bottle 33mm PWKs K&N pods 16/42 gearing with 22inch tyres the carbs are brand new and came with 52 pilots, CGL needles in the middle clip, and 165 mains. I went straight to a 170 main and took it for a run, we had a tacho on it too: 170 mains: pulled real hard, 10300rpm in 6th gear, plugs were a light tan colour on the left, grey on the right i skipped straight up to 210 mains thinking it would just be way to rich and wouldnt pull it cleanly but: 210 mains, pulled just as hard (couldnt really tell i guess), 10000rpm neat in 6th gear, plugs were a nice tan 2.5mm ring on the left, still looking a bit dry and colourless on the right (light tan colour) we didnt have any jets bigger than that except for 275 (drilled) jets that my friend used to run in a alcohol burning rotax 500 275 mains, wouldnt pull cleanly at WOT, 9000rpm in 6th gear coughing and spluttering up high, plugs wet and oiled up so obviously im going to now get some jets inbetween 210 and 275 and get it dialled in sweet, but WHY DOES THIS THING NEED SUCH A BIG MAINJET??? it is alot bigger than ive ever heard of anyone using, can someone explain this to me please? thanks, mark Edited September 9, 2007 by 4stroker Quote Link to comment Share on other sites More sharing options...
RZBansheeMan Posted September 9, 2007 Report Share Posted September 9, 2007 Because The RZ engines love fuel, I think the the exhaust duration is already in the near 200* ballpark when the powervalve is fully open, if I'm not mistaken that is closer to drag porting spec for the exhaust. I remember seeing those intakes and boysen ports on those jugs of yours and those things were massive, I would almost have to say that those T-5's might not be enough pipe for the way those things are ported. It seems somwhere here in the HQ's there might be some old topics on RZ conversions and jetting, and I almost want to say the some people were well into the 300's with mikuni carbs. Quote Link to comment Share on other sites More sharing options...
sredish Posted September 9, 2007 Report Share Posted September 9, 2007 also, you'll probably want a much richer needle than what is normally stocked in the PWKs. Do you know what needles you have in there? The first digit is the taper and controls 1/2 to 3/4/just about full throttle positions, higher in the alphabet is richer, so an EEK would be richer than a DEK. In my experience, getting the richer taper helps with the transition on fuel hungry motors and also helps with not having to get so crazy on the mains. Definitely worth a check, remember there's a lot more to a carb than just main jets, in fact, the needle does 80% of the carb's function. Quote Link to comment Share on other sites More sharing options...
4stroker Posted September 10, 2007 Author Report Share Posted September 10, 2007 thanks for the replies guys i was under the impression that the needle didnt affect WOT at the moment am only worried about WOT, as i am planning to race this quad in "beach drag" race where i will be holding it flat for 5 laps around two barrels that are 500m apart on the hard sand. and how can you say theres no way it needs a 210 main if it pulls hard and clean and revs to 10000rpm not trying to start an argument or anything i am just trying to learn as much as possible! the needleis CGL in the middle clip. thanks, mark. Quote Link to comment Share on other sites More sharing options...
4stroker Posted September 10, 2007 Author Report Share Posted September 10, 2007 ok so it seems that on the 3rd clip, the last part of the needle (10-12mm) is still in the main jet at WOT i will lift it up out of there (4th or 5th clip) and see how it behaves then the needle is a CGL, what is the next richest needle? thanks, mark Quote Link to comment Share on other sites More sharing options...
sredish Posted September 10, 2007 Report Share Posted September 10, 2007 the needle is a CGL, what is the next richest needle? richest how? We'll use your needle for the example. The first digit "C" is the Taper and affects 1/4 to WOT, it peaks at 3/4 throttle but still has an affect on WOT, so going to a richer taper "D" will help with bringing the main size down and transitioning to WOT faster. The second digit "G" is the L1 or length. The L1 and clip work together in gauging the total depth of the needle into the seat and work the areas from 1/8 throttle to 3/4 throttle but peaks in the 1/4 to 1/2 range. The last digit "L" is the diameter and affects basically idle to 1/4. You could go to a DGL to richen the 3/4 to WOT areas. If you felt that you needed less length, as if you were using the bottom most clip position and needing more, which sounds like is not the case, then you could try a DEL for a shorter needle. Does any of this make sense or is it confusing. Go to the page below to look at all the available needles. The page is confusing at first, but after you figure it out, it's quite simple. http://www.sudco.com/vol33/135-136.pdf Here's a chart I snagged off of Sudco a long time ago to help you as well. Quote Link to comment Share on other sites More sharing options...
BellicoseBanshee Posted September 10, 2007 Report Share Posted September 10, 2007 Go to the page below to look at all the available needles. The page is confusing at first, but after you figure it out, it's quite simple.http://www.sudco.com/vol33/135-136.pdf Here's a chart I snagged off of Sudco a long time ago to help you as well. Here is one from the Keihin website. I think this one is easy to read. It is for 34-39mm PWK and PJ, but it should work for his 33 PWK needles as well, correct? Jet Needles Quote Link to comment Share on other sites More sharing options...
4stroker Posted September 10, 2007 Author Report Share Posted September 10, 2007 richest how? We'll use your needle for the example. The first digit "C" is the Taper and affects 1/4 to WOT, it peaks at 3/4 throttle but still has an affect on WOT, so going to a richer taper "D" will help with bringing the main size down and transitioning to WOT faster. The second digit "G" is the L1 or length. The L1 and clip work together in gauging the total depth of the needle into the seat and work the areas from 1/8 throttle to 3/4 throttle but peaks in the 1/4 to 1/2 range. The last digit "L" is the diameter and affects basically idle to 1/4. You could go to a DGL to richen the 3/4 to WOT areas. If you felt that you needed less length, as if you were using the bottom most clip position and needing more, which sounds like is not the case, then you could try a DEL for a shorter needle. Does any of this make sense or is it confusing. Go to the page below to look at all the available needles. The page is confusing at first, but after you figure it out, it's quite simple. http://www.sudco.com/vol33/135-136.pdf Here's a chart I snagged off of Sudco a long time ago to help you as well. hey thanks alot man it is making perfect sense! i am going to experiment with the CGL needles for a start, lift them up out of that hole and see if that richens it up enough to bring the main jet down a couple sizes. if it doesnt work the way i want it to i will get some DGL needles (if they exist?) and go from there. a richer taper would be less taper yeah? as in smaller in diameter, so that more fuel can flow around the needle out of the jet, as opposed to a leaner needle which would be fatter and effectively choke the main jet up? Quote Link to comment Share on other sites More sharing options...
4stroker Posted September 10, 2007 Author Report Share Posted September 10, 2007 another thing i just thought of, could my plugs be too hot for this motor? it has 19cc domes and im still running BR8ES plugs. in conjuction with a needle change i may go to a 9 (colder) plug and do some plug chops then. theory behind this being that with the higher compression and the standard plugs, it may be getting too hot in there and burning too much fuel. the plugs arent blistering or anything yet but hey its worth a try right? Quote Link to comment Share on other sites More sharing options...
sredish Posted September 10, 2007 Report Share Posted September 10, 2007 (edited) another thing i just thought of, could my plugs be too hot for this motor? it has 19cc domes and im still running BR8ES plugs. in conjuction with a needle change i may go to a 9 (colder) plug and do some plug chops then. theory behind this being that with the higher compression and the standard plugs, it may be getting too hot in there and burning too much fuel. the plugs arent blistering or anything yet but hey its worth a try right? They do make a DGL with the richer taper. A richer taper actually has more taper so as it falls to the point quicker. a richer tapered needle will have less diameter as it falls when compared to the leaner tapered needle. the BR8ES should be fine. the way you can tell if it's too hot or not is by looking at the ground strap. there will be a color change and it should occur in the bend of the ground strap towards the outer edge. But, the "8" plug should be fine. the heat of the plug has nothing to do with how it burns the fuel, they all burn the fuel the same. the heat of the plug has to do with how well it transfers heat internally in the plug. the plug has to transfer heat properly for it to operate at its best but has no affect on spark. above all, always keep in mind the throttle position that the jetting change affects and pay attention the to the problematic areas in the throttle position so you can jet accordingly. Edited September 10, 2007 by sredish Quote Link to comment Share on other sites More sharing options...
Matt96shee Posted September 11, 2007 Report Share Posted September 11, 2007 170 mains: pulled real hard, 10300rpm in 6th gear, plugs were a light tan colour on the left, grey on the right wow, 10K in 6th...with a 16tooth sprocket....how fast were you going? and, how did you hook up your tach? Quote Link to comment Share on other sites More sharing options...
sredish Posted September 11, 2007 Report Share Posted September 11, 2007 Matt, I'd love to take a spin on that quad of yours.... RZ jugs with some PT Hi Revs..... I bet thing has a really nice powerband and runs hard! Quote Link to comment Share on other sites More sharing options...
4stroker Posted September 12, 2007 Author Report Share Posted September 12, 2007 wow, 10K in 6th...with a 16tooth sprocket....how fast were you going? and, how did you hook up your tach? well according to that banshee gearing calculator, 10k in 6th with 16/42 gearing and 22inch tyres is 99mph... the tach isnt the RZ tach, its one of those ones that butterfly clips to your spark plug lead. got a hold of some EEK needles from a friend that im going to try soon, let yooz know how it goes, hopefully i can come down a few mainjet sizes with them in there... Quote Link to comment Share on other sites More sharing options...
sredish Posted September 12, 2007 Report Share Posted September 12, 2007 got a hold of some EEK needles from a friend that im going to try soon, let yooz know how it goes, hopefully i can come down a few mainjet sizes with them in there... sweet. let us know how they work out! Quote Link to comment Share on other sites More sharing options...
4stroker Posted September 24, 2007 Author Report Share Posted September 24, 2007 got the jetting pretty much sorted on the weekend. before i even tried the EEK needles, i put my needles (CGL) on the last groove, so they were in the highest position. this was way too rich for any throttle position above 1/4. i came right down in mainjet size to 170 (from 210) and still couldnt get it up onto the main jet. so i dropped the needle one position, and the bike ran like a champion, there was an ever so slightly rich stumble around 3/4, but past that it just ripped and damn near pulled my arms off! i did a bunch of full throttle plug chops and went up in mainjet size to 182, the plugs look good, maybe slightly lean, but the bike shop didnt have any 185s or bigger so they have ordered a bunch for me and i will need them id say. thanks for your help sredish! Quote Link to comment Share on other sites More sharing options...
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