srp

My engine design and simulation software uses Young's Modulus to study reed behavior and lift, the software will predict total reed lift, reed cage time/area, actual time/area across the petals, reed petal frequency, intake velocity, BMEP, direction of flow at important timing events and amplitude inside the intake pipe as the reed petals close. The software will predict an unstable reed petal if the lift ratio is much above 30% (reed max lift divided by reed un-clamped length), If the reed is unstable and floats it will close late and the inertia of the intake pipe will have to do most of the work keeping the charge in the crankcase. If everything goes right the reed closes on time and the charge inside the intake pipe sneaks into the crankcase just as the reed petals close, this will raise pressure inside the crankcase much like a very small supercharger would do. Cubs above 392 cc will have excessive primary compression and reed tip ratios at and above 30% unless the builder has adjusted it. The reed stops on the VF4 will help stable the reeds on these engines or so the math says. To learn more read Gordon Blair's Design and Simulation of Two-stroke Engines (Chapter 6), for the math Gordon Blair's The Basic Design of Two-stroke Engines and Google Young's Modulus.

I did simulation on the VF3 and VF4 and agree 100% with John on this one, simulation shows gains on 4 mill and 10 mill engines. This reed cage helps with a problem that most don't even know they have (reed tip ratio above 30%).

The corrected horse-power numbers at Denver will not be the same as sea level numbers on a high output two stroke. There is no air at 5000 feet for the engine to produce the same heat as it would at sea level, so a large volume expansion chamber will not work the same way at 5000 feet as it does at sea level. You have to run chambers with very little volume for that size of engine to make any real power, no correction factor will compensate for an expansion chamber that is too big for the amount of heat that is being pumped into it.

The correction factor can be changed anytime after a dyno pull, you can chose from uncorrected, std, sae and one other on a Dynojet. You can print and compare runs with different correction factors at will. Heating the stack will raise the horsepower output and a simple turn of a potentiometer on the weather station will raise power output just as J-Madd said. There are lots of other ways to manipulate the output of a Dynojet that I did not mention.

Have your dyno day on a day that everyone can be there, I want to be there for every dyno pull that will be posted. I do not have a dyno, I have had an independent shop dyno and tune for all the dyno sheets I have and all are 100 percent legitimate. The elevation in Sweet Home OR is the same as Oklahoma, This makes me confident enough to say that any Redline tests on 100+ horse Cubs,Cheetahs,T-rex or Twister engines on gasoline will look just like the dyno sheets that Jim posted comparing Sniper in-frame to Shearer in-frame. At this dyno test I will put Sniper in-frame up against Shearer IF or OOF on 100+ horse gasoline engines. I will not say that Sniper is the best on cast Servals, lightly ported Servals and all cast Cubs. Good porting is mandatory for them to be a better pipe. Every dyno sheet Jim posted was on gasoline comparing Sniper to Shearer, gas is the fuel of choice for most of my customers and most people with in-frame pipes. I am free most any time and can stay a few days if needed to finish testing. Cameron, thank you for offering to do these tests and to set the record straight.

Cameron, when you post the sheets have the notes, run conditions and correction factor on the sheet for reference....Thanks Ragun, I put a 1 inch ID stinger on all big bore gas engines and a lot of alcohol engines. Ims, this set is standard with removable stingers.

That dyno setup should be good. I hate for anyone to get their pipes scratched swapping out pipes, I have a set of in-frame test pipes you can test with. Ragun, I have not tested ceramic or power coatings for power gains or loses.

Rocket and CPI will both do better in a pipe test than some think if the bike is geared to simulate the load of racing. Any large volume pipe needs the exhaust gasses to be at maximum temperature to come into sync. Any dyno runs that do not spin the drum close to 80 mph on a 85+ horse engine will not show true potential of the engine or pipes on an ATV dyno. A car dyno does not need that much gear with the large rollers. Low exhaust gas temperatures in a large volume pipe will stop expanding and tumble, this acts like a wall inside the pipe. A 17/41-43 gear works good on 20 inch tires and a 19/41-43 gear works good on 18 inch tires. Using an eddy-brake will only simulate racing with your foot on the rear brake and will not let the engine peak at its natural RPM. Dyno runs with too low of a gear ratio will almost always have a bigger numbers with a smaller volume pipe, smaller stingers help as well to get a flash number under geared.

Oh yea, it just pulls a very small amount of air from the choke horn. Some of the older Lectrons did not have chokes and or the holes drilled that feed the choke, that's why I mentioned a working choke.

Any use of housing insulation should be non formaldehyde.

Yes Rainman56, if you have a working choke, the kit allows you to run the metering rods two turns rich and allows the idle to be fully adjusted from the secondary idle screws. If you can bottom out the idle slide screws and still not get the engine to idle up high enough for a good stable idle and you have to lower the metering rods so low it stumbles in the midrange to get a good idle, this kit will work very well for you. The need for this kit is much higher on gas than alcohol, many new Lectron carbs ordered for a four stroke engine will come with similar screws already installed for easy idle adjustment. On a first time tune on gas and alcohol, this kit will save tuning time be allowing the engine to run and idle perfectly with less metering rod adjustments.

Congratulations Brad Painter for the wins in the 431cc-525cc and 526cc-650cc classes at the first race of the year, Brad won both classes with a 10 mill cub.

No brad I don't know his name but Jim does, he sold the pipe. That guy told the other guy with the YZ85 his pipe was built in California, so he don't know I built it.

I did pipes for two dirt-bike hill climbers running in West Virginia on the 400 foot hill, both have custom in-frame pipes, one is a 610 DM and the other is a YZ 85. I have been told the DM was the fastest on the hill last year (with a pro rider), but let me say this is secondhand information, will post some video if I get any. I'm sure Loco could get the scoop on this.

That record was set when I was just getting started, I would love to see what a hand coned Sniper would do on Jason's bike, built for his engine.

J-Madd told me Jason Menz's record setting bike had a modified small bore RDZ OOF pipe, but what does he know about that? Also Rob @ RDZ told me Jason Menz's bike had a RDZ small bore OOF pipe on it when it set the record, and its on his web site, but what does he know?

Cory, Last month the local dyno shop I use Sandtrax (918-445-4153) dynoed a their customers cast 421 cub with 28 PWK's on gas, it made 89.75 HP with the standard Sniper IF. Ed said the engine was rich safe.

John, You have a distorted view of reality, the paying members have a product reviews section to share their experience with a product. The (sponge off of everyone else) membership you have does not have one or you can't read, but reason for not being a paying member is the very same reason you cannot give any first hand feedback. You boasted about posting dyno sheets from 3 reputable builders, lets get them posted. Dyno feedback from RDZ (you know, that guy that really does have the record setting pipe for 300 feet) and Passion tells me Sniper IF makes much more power than Shearer IF on their engines.

Please show and tell everyone what you are talking about.

Rob does do good fab work. Fresh off the dyno, his big bore pipes made 3 more horsepower than Shearer and his small bore stamps are on the fastest cub with a record. So he knows a little bit about pipes and what is real.

Bring your 421, a 215 pound rider and a grand to Whitefield and put your money where your mouth is.

You being dana's husband and builder, it easy to see why you don't understand. Two stroke engines are designed at the crankshaft. Everyone knows but you, the losses through the transmission, chain and rear axle have to be added back in. That number is 19 percent on atv's. Passion has posted a 465 gasoline video and dyno sheets of a 200+ BMEP engine at the crankshaft, the engine made 113.78 hp at 9400 rpm, that is 201 BMEP at the CRANKSHAFT on gasoline. Do you not know the temperature during combustion is 4000 Fahrenheit and the exhaust is the hottest during blowdown and then cools progressively until the exhaust port closes? Having an average exhaust temperature of much more than 1000 degrees Fahrenheit will melt the pistons. But the short time the piston is exposed to 4000 degrees during combustion and the short time of blowdown, the pistons do not melt. You are right about something, it's hard to make big power from gasoline and Passion does it everyday, in fact won a championship at BBDR last year on gasoline with same 465 cub. http://i57.photobucket.com/albums/g215/passionre/PassionDyno-072011.jpg

I should have known that dana is the only one here that don't know all software, math and empirical formulas are based around gasoline.

Who is faster, dana or tedd1? Is tedd1 her builder?

Lets match race at the HQ ride. And anyone else that truly wants to race should show up too.