SLORYDER Posted June 24, 2010 Report Share Posted June 24, 2010 Ok so I did some math and figured what the port timings would be like if you installed different cranks and spacer plates. This pertains to BASE PLATE spacers. When I mention 1 or 2mm spacer I am talking about the COMBINED thickness of the extra gasket plus the spacer.Also I used .020" for the deck height due to the base gasket; this will be apparent in all calculations. 4mm crank results are using a 115mm "long rod" I am fairly certain that these durations are within 2 degrees;however I am not an engineer nor have I calculated these durations with a scientiffic calculator. Which I would recommend doing if you are considering a build based on these numbers 1. Bone stock cylinders: 183.5 exhaust 118 transfers 2. Bone stock cylinders plus 2mm spacer: 190 exhaust 130 transfers 30 blowdown 3. 4mil crank no spacer: 182.5 exhaust 127.5 transfers 26.5 blowdown 4. 4mm crank 1mm spacer: 187 exhaust 130 transfer 27.5 blowdown 5. 4mm crank 2mm spacer: 193.5 exhaust 137 transfer 27.75 blowdown It seems like for a do it yourselfer with limited tools and knowledge you could get some big gains for cheap if you know what you are doing. Obviously there are other factors involved and simply installing the spacer may do more harm than good. Note that obtaining these durations using a spacer would obviously not yield the same hp numbers as if you had it ported properly; however the "bang for your buck" factor would be high. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 24, 2010 Author Report Share Posted June 24, 2010 (edited) If you look at the numbers you can see how easy it would be to simply drop in the 4mm crank and hot dune/ drag port the cylinders yourself. All you would have to do is lower the intake ports 2mm, the exhaust port 2mm, widen the exhaust port by about 4mm and raise it 3mm. Then install a thicker head gasket to fix your squish and you'd have a 70hp bike for the cost of the crank and a new head gasket if you already have a dremel and some bits. Edited June 24, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
blowit Posted June 24, 2010 Report Share Posted June 24, 2010 If you look at the numbers you can see how easy it would be to simply drop in the 4mm crank and hot dune/ drag port the cylinders yourself. All you would have to do is lower the intake ports 2mm, the exhaust port 2mm, widen the exhaust port by about 4mm and raise it 3mm. Then install a thicker head gasket to fix your squish and you'd have a 70hp bike for the cost of the crank and a new head gasket if you already have a dremel and some bits. What were you using for stock port heights? Some of those numbers are good, some are not. The last one is a bit off. Just not sure how you are calculating this. I dialed in on your stock timings and them applied those to the other setups. Some were on, some were not. Can you post your formula? Brandon Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted June 24, 2010 Report Share Posted June 24, 2010 Im not critisizing you about using the math,I have used the math for a while.I didnt even know they made a 1mm spacer plate.If you bolt those plates up and run it on a wheel those numbers will change,without looking at my papers I would say those transfer numbers off by more than a few. Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 24, 2010 Report Share Posted June 24, 2010 If you look at the numbers you can see how easy it would be to simply drop in the 4mm crank and hot dune/ drag port the cylinders yourself. All you would have to do is lower the intake ports 2mm, the exhaust port 2mm, widen the exhaust port by about 4mm and raise it 3mm. Then install a thicker head gasket to fix your squish and you'd have a 70hp bike for the cost of the crank and a new head gasket if you already have a dremel and some bits. Are those port sizes with or without the stroker plate? Because it sounds like cutting the ports to those numbers are without a plate. If your not running a plate you need stroker domes. I know after looking at my 4mil cylinders there is a lot of porting done to get into the 70-75hp range. Its not just opening up the exhaust port and transfers. The port angles, port shapes, and the port tunnels are all different then stock to get a well rounded motor. It doesn't take much to really screw up how the motor runs with the wrong angle or port shape Quote Link to comment Share on other sites More sharing options...
AKheathen Posted June 24, 2010 Report Share Posted June 24, 2010 yah, i believe the blowdown numbers are actually allot less favorable than that. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 24, 2010 Author Report Share Posted June 24, 2010 Like I said, the numbers are close enough for practical reasons. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted June 24, 2010 Report Share Posted June 24, 2010 so, "practical means the difference between 60 and 80hp? or, peak hp, vs, total profile? if you get the numbers closer, it will make a huge differnce. i'm not geven gonna go into my opinion on the spacer plate again Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 24, 2010 Author Report Share Posted June 24, 2010 It doesn't take much to really screw up how the motor runs with the wrong angle or port shape I agree. Which is why it is easy to make power with a 4mil crank. You don't have to worry about touching the transfer roofs at all. You can reach your time area numbers by LOWERING he port floors which is foolproof. And I'm sure just about everyone knows that increasing your transfer time area and opening the exhaust port are the 2 biggest factors in porting a banshee once you get your timings correct. I love how you guys come on here like you're trying to be so helpful, when in fact you are not trying to help anyone. If you know better, why don't you post some numbers guys, huh? I can guarantee you 4mm crank +2mm head gasket +raising the exhaust port 2mm and widening 3mm will make a really strong all around engine. Probably in the 60-65 hp range w/ supporting mods. Another 1-2mm wide and 1-2mm up and you will have a more top end biased engine. You guys can stop with the act Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 24, 2010 Author Report Share Posted June 24, 2010 (edited) Ok here are my latest and greatest numbers I used This program to determine durations, using 185.5/ 118, which are very close to accurate when factoring in the .020" base gasket. http://www.nclra.org/Programs/PortTiming.php?GO=1&Stroke=54&RodLength=110&PortHeight=24.5&PortTiming=125.57&Deg=Calc+Duration Stock---------------------------------------------------------------------183.5/ 118 29bd Stock +.060" base gasket--------------------------------------------------188/ 124 32bd Stock + 2mm base gasket---------------------------------------------------192/ 129 31.5bd 4mm crank no spacer .080" head gasket-------------------------------------185/ 125 30bd 4mm crank .060" base gasket .040" head gasket-----------------------------189/130 29.5bd 4mm crank 2mm spacer stock head gasket------------------------------------192/135 27.5bd These blowdown numbers are within 1 degree Edited June 24, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted June 24, 2010 Report Share Posted June 24, 2010 Slo , is .020 normal base gasket? Is the .080 head gasket close to 2mm? Cause that's what my son's shee has. 4mm stroker, long rod , thick ass copper head gasket, forgot what pistons. Also ,are those timings with long rod stroker ? Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 24, 2010 Report Share Posted June 24, 2010 Can you post what numbers you feed into the calculator for each one of those? Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 24, 2010 Author Report Share Posted June 24, 2010 Slo , is .020 normal base gasket? Is the .080 head gasket close to 2mm? Cause that's what my son's shee has. 4mm stroker, long rod , thick ass copper head gasket, forgot what pistons. Also ,are those timings with long rod stroker ? Not sure what the normal gasket is. I believe it is around .015-.025". .080" is 2mm. So what you get from the .080" of extra stroke and the .060" of extra gasket (assuming .020" is like milling the head .020". And yes, timings are with the long rod. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 24, 2010 Author Report Share Posted June 24, 2010 (edited) Can you post what numbers you feed into the calculator for each one of those? To get my port height, I use 54 mm stroke/ 110 rod and 183.5 dur to calculate the port height For the transfers I use 118 to get the port height. Then I switch over to 58mm stroke, 115 rod, and go up 2mm on my port height because the piston falls an additional 2mm below the port, and go from there. Edited June 24, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
AKheathen Posted June 24, 2010 Report Share Posted June 24, 2010 there you go attacking people again- it's not that we will not post numbers, or lie about it. even brandon/mull is jumping in to help, it's that we don't want to post unproven or mistaken numbers, because once someone takes it in good faith as fact, not estimate, and hacks some cyls, then it's really your fault for screwing up someones cyls. not technically, or legally, but morrally. i can tell you that the 4mill-no spacer was more accurate on your first post, to the best of my knowledge, but i'm not 100% how close on the transfers. only way to know is when i drop the crank in and check it. oh, and i wouldn't think of asking a builder to spit out too much info, since that is knowledge that they spent years and tons of money to gain, and puts food in their families mouths. the builders on this site are above and beyond helpfull Quote Link to comment Share on other sites More sharing options...
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