Results 1–30 of 190
If you need a richer jetting and the steps of main jet sizes are too big then you can reduce the shroud height little by little till the jetting is just right. The "steps" % change between a #60 and #65 for a small carb is 8.3% which is too much. For a larger carb the % change between a #120 and #125 is 4.15%. I think the ideal step for all sizes is 2.5% which only exists for the larger
One thing I have noticed about haters on bike forums. Other than being negative, self-loving, asinine, corrupt, petty, totally lacking in logic (low IQ), they are always fuckingAMERICANS !The Europeans have class and culture. Only americans are rednecked assholes. Your continuing fall from grace is cherished worldwide and we will mock your downfall.It couldn't happen to a more deserving bunch
You obviously have not a clue about how extensive and detailed my pipe software is. It always hits right on the head. You should be informed about something before making erroneous statements.www.dragonfly75.com/motorbike/ECtheory.htmlwww.dragonfly75.com/moto/portsMS.htmlYou've "seen my pipes and aren't impressed". ha ha, what a hoot. I don't know shit about welding and I
Mike Boyd, I never said you couldn't "modify cylinders for gains". If I thought that then why would I make a porting calculator? What I was referring to is that we are mostly stuck with the # of transfer and exhaust ports they come with, the basic design. Yes a few people have drilled in exhaust auxiliary ports, a very very few people compared to everyone who has put a tool to their
I'm an American in South America and when I raced motocross against the latinos I almost always got the best start. Of course these people don't measure anything and would never consider using a computer program to help them get their engines right. And I left them all in my dust.If you're going to do something then do it right.
Alan the expansion chamber calculator took 7 years to finish. All during that time I offered it in its "unfinished" state for free. Now it is finished and costs $25, a modest fee for it being the only decent program using a return wave simulator. People get good results using it now. Please go to my site to read more about it and see the testimonies: www.dragonfly75.com/moto/calculators.
OK, good for you. But I know most people won't attempt to do such. But for those who do maybe you should tell them how you did it and offer tips and advice. I'm all for going to extremes to better your ride.
Also;If you want to increase top RPM you have to shorten the header of the expansion chamber. But only with a good expansion chamber calculator will you know how much to shorten it by.If you want to port for more emphasis on high RPM power you don't know to raise the exhaust port, raise the transfer ports, or raise both. This is where a good porting calculator comes in. It will tell you if yo
You have to use a good squish velocity calculator. Don't leave importance stuff to guesswork.
Yes it is possible to add a boost port and/or auxiliary ports but it takes a very determined and skillful person to do such and they are never as good as those made by the factory. So this is the exception, not the rule. So generally speaking rule #2 is true.
Rule #1: There’s more or less a set amount of power available for you to manipulate. If you port for high RPM power then your low/mid-range power will suffer. You are robbing Peter to pay Paul.Rule #2: You are pretty much stuck with the porting arrangement the factory put in your cylinder. If the exhaust port is single with no auxiliary ports then you are stuck with that. If your transfers have li
Cool but most of what I know is at my two sections of my web site: www.dragonfly75.com/motorbike/ www.dragonfly75.com/moto/
I just made that spreadsheet so how could it be a repeat?
Crappy free programsSome programs are even based on the formulas proposed by Gordon Jennings from way back in the early 70's. Man they were just beginning to investigate back then. Basically they knew next to nothing.Jennings main shortcomings;0. He assumes the same temperature and sound wave speed inside all pipes.1. Because of his temperature error his calculations for the tuned length were
Notes on my free spreadsheet of mini 2 stroke calculatorsSome of these calculators have never been available till now although engineering types have always been able to figure this stuff out.Maximum Average Piston Velocity CalculatorThe average (mean) piston velocity is what most calculators go by instead of the maximum velocity which is fine because they maintain a set relativity to each other n
After minimizing flow resistance and widening the ports then you have to think about whether or not you want to give the engine more power on top that is taken from the bottom (better high rpm power at expense of low rpm power). To go in that direction you first need to find out the port durations which you can do by following instructions at http://www.dragonfly75.com/moto/porting.htmlIf you do t
When looking at what carb sizes manufacturers usually put on their bikes and the resultant air velocity at max RPM I came up with this chart and then the Excel spreadsheet that calculates your carb air velocity and where in the range of enduro to motocross it falls within. What is curious is how the trend reverses when going below a 125cc engine. That may be in order to try to maximize engine powe
too many crazy people on this forum
It's unfortunate grasshopper that the oil manufacturers most often do not pay to have their oil graded and so puts their own rating on it. So they could label it FC but it could be FB. There is no law preventing them from doing that. That label is often just wishful thinking. What I did is to look up the actual oils they used and look up their characteristics and from that I made my own guess
If you want more information just click on the link I have provided that takes you to my web site.Obviously there will be differences in engines that will require jetting changes and so I recommend people determine the idle and main jet size the old fashioned way. But then what about the slide cutaway, needle, needle jet? You are fucked on choosing them without a jetting calculator. There might be
to find the answer to the question "how does it work?" just scroll down on this page to find the explanation of how the calculator works: http://www.dragonfly75.com/moto/carbjetting.html
this is a good page on the subject: http://www.mummbrothers.com/SRF_Stuff/Secrets/Driveline/Air_Fuel.htm
true and here's my web paging about removing alcohol: http://www.dragonfly75.com/moto/no-alcohol.html
Well then that's just showing that the stock jetting for a VM20 is appropriate for a lot of moped engines but it doesn't make Mikuni a "magic" brand by any stretch of the imagination. I started to make my jetting calculator after realizing by trial and error I could never get my VM20 to work right on my 100cc 2 stroke street bike. I had to have in depth analysis of what was goi
not a "trick question" but rather a dumb answer
that's a huge carb for such a small engine. The air velocity in it will be low which will make it hard to jet, but it's possible. What is the cross sectional area of the passageway between the engine and the carb? The carb should have that same size.
c'mon Mikuni users, I know you're out there. Post your data here and hopefully it will help someone else in the future.
Trust me, it is very useful. If you want information about this then please just take the time to read my site. I don't know why you say you have no clue about how much ethanol is in your gas because it's almost always printed right there on the gas pump and if not then it takes about 60 seconds to test how much ethanol is in gas by using this tester
amzn_assoc_tracking_id = "mopedarmy-
Dirty, the same way the motorcycle engineers do, I start with formulas. So the formulas can get you within one size of each needed jet. Then you perfect it by trial and error. So if you want to put a different carb on your bike then you can see what the program says will get you close to perfection and then buy half as many jets as you normally would. That's just concerning the idle and main