BigRed350x Posted November 20, 2004 Report Share Posted November 20, 2004 I went down to the metal fabrication labs in the engineering building and had them make me a two into one tube for the banshee. I got a 40mm Mikuni carb for it too. I can't wait to get it all put together and jetted. Should be fun. Soon as I get some batteries for my camera I will post a pic. Quote Link to comment Share on other sites More sharing options...
FIRST BANSHEE Posted November 20, 2004 Report Share Posted November 20, 2004 sounds like you work at a cool place, let us know the results. Quote Link to comment Share on other sites More sharing options...
Wallrat Posted November 20, 2004 Report Share Posted November 20, 2004 Sweet, I've been thinking about doing the same thing. 40mm sounds awfully big though...try it and if your bottom end feels sluggish you may wanna drop down to a 35mm or so. Quote Link to comment Share on other sites More sharing options...
broke Posted November 20, 2004 Report Share Posted November 20, 2004 I've been wondering if the bigger carbs could be made to work with a 2:1 set up. If you really think about the areas of the different carbs it doesn't seem to be that big. (1) two stock carbs 26mmx2 1061 cubic mm (2) 40mm single 1256 (3) 35mm single 962 (4) 33mm single 854 A 37mm carb would give you roughly the same area as a set of stockers at 1075. I'm sure there are other factors at hand, but if you just go by the numbers anything short of a 37 would give worse top end than stock. Keep up the good work and let us know how it goes. Quote Link to comment Share on other sites More sharing options...
red ore Posted November 20, 2004 Report Share Posted November 20, 2004 (edited) keep in mind with dual carbs, only one carb is working at a time. The single carb will make the carb work "steady", and thats why trinity refers to it as a "constant velocity" I wanted to make my own also at one time (out of stainless!!!). i was going to copy the trinity one, and had the engineering department cut all the stuff out for it. I soon lost interest (racing season started) and never finished it. I dont work there anymore, so BOOOOO for me! lol I hope it works, keep us posted for sure! Edited November 20, 2004 by red ore Quote Link to comment Share on other sites More sharing options...
bansheefreak Posted November 20, 2004 Report Share Posted November 20, 2004 keep in mind with dual carbs, only one carb is working at a time. The single carb will make the carb work "steady", and thats why trinity refers to it as a "constant velocity" I wanted to make my own also at one time (out of stainless!!!). i was going to copy the trinity one, and had the engineering department cut all the stuff out for it. I soon lost interest (racing season started) and never finished it. I dont work there anymore, so BOOOOO for me! lol I hope it works, keep us posted for sure! 282994[/snapback] with dual carbs the work at the same time thats why you have to sync the carbs... Quote Link to comment Share on other sites More sharing options...
Wallrat Posted November 20, 2004 Report Share Posted November 20, 2004 I never liked the look of Trinity's. I wanted to copy Graydon's 2:1. Basically its 2 flanges for the intake side, and then 3 pieces of pipe welded into a 'Y' shape. Quote Link to comment Share on other sites More sharing options...
sredish Posted November 20, 2004 Report Share Posted November 20, 2004 bansheefreak, he's talking about the flow of air, not the mechanical part of the carb, the airflow pulsates (stops and goes repeatedly) with dual carbs as one cylinder sucks air, then the other, especially with a 180* twin. Broke, volume is only half the equation to proper carb setups. You have volume, but volume is nothing without velocity. So smaller carb(s) = less volume, more velocity larger carb(s) = more volume, less velocity. If you have a lot volume without enough velocity, the airflow won't be moving too fast, it won't pull the fuel from the jets properly (vacuum) and therefore you'll have jetting issues and be low on power. This is why large carbs are often more suited to top end setups, because you have more velocity at higher rpms. If your low on volume, you'll probably have a lot of velocity, and jetting won't be hard, but it won't pull as much air as your motor wants/needs at higher rpms. Generally, low/mid power doesn't suffer because you'll have good velocity in those areas but your mid to top end power could suffer depending on how short you are on volume. The secret is to find the right combination of both to perform at it's best. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted November 20, 2004 Author Report Share Posted November 20, 2004 Well I have the 40mm I got for this setup, I have a 36mm Flat slide BSR carb sitting in the garage, and a 38mm a friend offered to me, so I have lots of options for what to use. My design is kinda like the one described above. I don't like the look of the trinity either so mine actually has pieces of pipe shaped tube going from both reed boots back to a Y then a rubber flange where it mounts to the carb. I still have to go through and remove all the endges from the casting pour and smooth out all the "descrepencies" from the mold I made. My 40mm carb needs a cleaning and some new breather hoses. Hopefully some time Sunday morning I will be able to post pics for everyone. Oh yeah... this setup might be used with a nitrous system, so I don't know if that makes any difference with the 40mm carb setup for sredish. Thanks for the input everyone! Quote Link to comment Share on other sites More sharing options...
broke Posted November 20, 2004 Report Share Posted November 20, 2004 Sredish, Yeah, I know there is alot more to take into consideration besides just volume. I'm posting this more to learn rather than argue over stuff I know very little about. The 2:1 has constant velocity because each cylinder is pulling air 50% of the time or @180 degrees of engine rotation. Considering how long it actually takes for the intake ports to open and close, how much vaccum is actually lost on one side? I will base this off of 6000 rpm just for simpler math. At 6000 rpm the motor is turning over 100 times a second. Which is 200 firing cycles a second on a Banshee. If you just look at one cylinder at a time it's back to the 100, that means that the intake tract is seeing vacuum that many times also. Considering how fast the intake charge is going through the carb(s), reed and intake tract, How much would it actually slow down in 1/100 of a second? I'm just curious. Granted on a 2:1 this number is moved down to 1/200th of a second. I'm just curious if the minute amount of time difference really means much. I would actually love to use a 2:1, but I don't think the carb sizes that it uses would be enough. I would like to hear how yours and others with ported motrs like the 35mm single or if any one had tried swapping back and forth on ported motors. This is getting kind of long winded so I will stop here. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted November 20, 2004 Author Report Share Posted November 20, 2004 Well I just finished cleaning up my new intake. My jugs are ported and I have quite a few different carbs to play with on the new setup, so I will let you know what works best for me. I will be using a 40mm Mikuni, 36mm Mikuni, 38mm Mikuni, and a 34mm Mikuni carb. I will get them all jetted right and take all of them out to the dunes for a weekend when I get the new top end put in and will post what worked best for me doing different things. Quote Link to comment Share on other sites More sharing options...
joshv5.0 Posted November 20, 2004 Report Share Posted November 20, 2004 Well I just finished cleaning up my new intake. My jugs are ported and I have quite a few different carbs to play with on the new setup, so I will let you know what works best for me. I will be using a 40mm Mikuni, 36mm Mikuni, 38mm Mikuni, and a 34mm Mikuni carb. I will get them all jetted right and take all of them out to the dunes for a weekend when I get the new top end put in and will post what worked best for me doing different things. 283092[/snapback] post pics of the intake Quote Link to comment Share on other sites More sharing options...
Holyman Posted November 21, 2004 Report Share Posted November 21, 2004 Yeah the pic would be great. I'm curious what size tubing you used and how you converted the rectangular opening to the round tubing. I find this to be the biggest problem with the Trinity... the actual passage is only about 1.125 square even though it looks like a rectangle on both ends. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted November 21, 2004 Author Report Share Posted November 21, 2004 My digital camera takes some kind of fancy battery and I don't have any around, so sorry about not posting a pic yet. I will post a pic as soon as I get new batteries. The intake basically mounts directly to the reed cage bolts (the four hex head bolts that hold the reed cage in place) with a metal flange that is part of the fabrication. It goes from about a 1.5" tube to the large square of the reed cage in a 1.5" long transition with a gasket that looks like what you get with a reed spacer. To give you all an idea of what it looks like before I get my pics posted, I based the entire design off of the intake manifold from an Arctic Cart Panther 440 snowmobile, I just changed the part where the intake will bolt up to the reed cages, and made it a little longer. - Jared Quote Link to comment Share on other sites More sharing options...
brock_fuzzy_69 Posted November 21, 2004 Report Share Posted November 21, 2004 i had considedered this as well i ahve atrinity intake that was on my machien when i baught ti but i know that a graydon style will def outflow it any day i had thought of using reed spacers for the part that bolts to the juggs could bolt them down to a steel plate to keep them flat and paralel while you are welding it up for the carb mounting i thought of an oval shaped 2 bolt flange that way you can buy the standard mikuni rubber intake boots from say sudco for round to square i think if you had to rectangular pieces joined yoiu coudl put it in a drill press and hole saw it through for the round tube to intersect............would look a little bit goofy tho but if you used a bolt on carb boot insted of the rubber hose like graydon did then you coudl make it from all quare Quote Link to comment Share on other sites More sharing options...
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