F.A.S.T. Racing 4 mil Serval Cub

[BUILDER]

05 please understand I am not knocking you bike at all I am sure it runs very well and pulls hard I was just pointing why lots of people are going to question the numbers. I look forward to running them side by side just to see how they pull if for no other reason. Just keep in mind I am kind of a fat ass so if you weigh like 150 it is not a fair race lol.

 

 

I am bolting on a 4 mill cub that has been decked down to lower the port timing on it and it has been cleaned up a little but not much at all and I have 34 pj carbs v force 3 reeds and the exhuast is still up for debate. I have snop's favorite pipes right now T-5'S but will be bringing at least one other set of pipes to see how it runs. I like dyno numbers and I will run it on the dyno but care much more about how I like riding it which I am sure you understand.

[05stroker]

Builder, I know you weren't knocking my bike. I understand why people reacted the way they did to the graph, we were expecting it. No hard feelings here. I'm glad you are going to have your bike down there so we can line up and see how they compare. Don't worry I am nowhere near 150. I'm 6'4'' and about 220. I'm just excited to get this thing in the sand where I can get some traction.

[05stroker]

Here is the "unloaded" graph with the RPM on the bottom instead of the MPH. All three runs are the Pro Circuits.

 

[WINDYCITYJOHN400]

I'd like to add a further statement.

(Let me set the tone of my comments, because I don't want this to sound like a bash fest or an argument.)

I'm just as interested in the SERVAL concept as anyone. So what I'm saying is just part of an open discussion where we are all trying to find information.

 

The statement that you can't compare one dyno to another is incorrect. You can compare ANY DynoJet inertia dyno to another. They will be within one HP of each other if they were side by side. (I'm not saying you can do this with a different brand, just Dynojet) We put a MX motorcycle on a DynoJet 188 in NY, Michigan, Chicago and Dallas. Same bike, much different days, wildly different weather and elevations. Numbers were never off by more than 3 HP. (No tuning was done, just 4 pulls per dyno) So unless your up in the high elevations, they are going to be close enough for a good comparison. An eddy current style DynoJet (When NOT using the eddy current brake) will also match other DynoJet inertia dyno's.

So yes, you can compare an M+M number with Snop's... as long as they are both DynoJet brand inertia models run in the inertia mode.

 

Also the premise that a CPI/Shearer pipe along with a bigger carb will only benefit the upper RPM HP at the sacrifice of low end power and rideablitiy has not been established in any way. It's completely possible that a bigger carb and pipe could help both ends of the RPM band. I find it strange that out of all the dyno curves for both HP and torque....the curves almost match each other. What I'm trying to highlight, is that if one pipe was vastly different than the other you might expect to see the curve of at least one of the pipes climb at a faster rate than the others at some point in the run. We only see a change in the final peak RPM areas.

The fact that your not using an A/F ratio meter to monitor the A/F balance shows that you have large holes in your research.

For example...what if the reason the CPI's are down on power vs. the others...is because the motor is lacking airflow or fuel. Your curves are so similar that it begs to ask, what is the common limiting factor that is causing this to occur? Carb size?

Snop, you said it yourself when you said ....... "Shane had me got on, I rode for 5 minutes and told him to change the pilo. He did that and it got even faster off the bottom and rips." Why would you need to change your jetting if you ran the bike in "Real world load conditions" on an Eddy Current Dyno? You just clearly proved that the jetting was off for that combo. Also you attempted to explain that if the CPI's wanted more fuel and weren't getting if from the 28's, then they would be lean and make even more power. That dosen't make sense to me. LEAN doesn't mean more power. Leaner than rich does. But too lean equals loss of power. Your changing of the pilot and seeing more power shows that you were too lean for the PC's doesn't it? So why wouldn't that make the CPI's fall on their face? The ONLY WAY to do a proper test of parts on a dyno, is to use an A/F sensor to monitor the mixture. You set a goal ratio...let's say 14.7 to 1 Air fuel ratio. (widely thought to be the ideal ratio for max power) then you jet each combo till the A/F readings match! Now you have tested each part to the same tune. NOTE: For sand we set our motors closer to 13.0 to 1 because sand will put a heavy load on a motor and cause heat to become a big factor in the jetting. This is the same as some dyno guys saying...."Find your max HP, then go up 2 jet sizes and you'll be safe."

 

Again, I don't claim to have all the answers, nor do I consider myself to be as experienced as many members here. I'm just offering a perspective and openly asking for others to share there opinions so that I, as well as others, might learn a little more or fill in holes in our understanding of things. After all, you all were kind enough to post some research you did, and we're just trying to see how it fits in with our understanding of things.

[BUILDER]

Builder, I know you weren't knocking my bike. I understand why people reacted the way they did to the graph, we were expecting it. No hard feelings here. I'm glad you are going to have your bike down there so we can line up and see how they compare. Don't worry I am nowhere near 150. I'm 6'4'' and about 220. I'm just excited to get this thing in the sand where I can get some traction.

 

 

 

LOL good deal because I am 6'4" 230 so we are about the same size.

[Snopczynski]

Shane needed a different sized pilot because we baselined the bike rich for break in and leaned it up to sharpen the acceleration after riding it and getting it broken in. This was done way before we put the bike on the dyno yesterday (2 weeks ago).

 

Shane rode the bike today for the first time since the dyno test and said it is way faster now, he made no changes to the jetting today before or after riding it.

 

Don't worry, the bike was jetted correctly for the pipe runs. Everyone has to remember, this is not about dyno testing a 421 cub motor with crazy drag durations. It is about dyno testing a Serval which has low-mid durations. It is ok for the low mid pipe to work on it better than the mid-top pipes and drag pipes.

[okbeast]

But some of the dyno testing done shows that the mid-top pipe and medium sized carb works great on this motor. Good power AND torque, with a great curve. I don't understand why you would stay with smaller carbs and low-end pipes if you can get more power with similar torque back-up?

 

I understand the motor "does what you need it to do" with that setup. Might as well just build a ported stocker and run some T-5's or pro circuits IMO, seems like a waste of money to buy a cylinder that can do way more than you want it to do, but choke it down. Much like people that build 421 cubs and put T-5's on them. But maybe that's not yall's thinking.

[Snopczynski]

But some of the dyno testing done shows that the mid-top pipe and medium sized carb works great on this motor. Good power AND torque, with a great curve. I don't understand why you would stay with smaller carbs and low-end pipes if you can get more power with similar torque back-up?

 

I understand the motor "does what you need it to do" with that setup. Might as well just build a ported stocker and run some T-5's or pro circuits IMO, seems like a waste of money to buy a cylinder that can do way more than you want it to do, but choke it down. Much like people that build 421 cubs and put T-5's on them. But maybe that's not yall's thinking.

This motor is in the same power range as everyone elses serval. It was dyno'ed on a conservative dyno with an engine brake. You know what, here is something for everyone to read. This was an email sent to me by my mentor this morning. He is a huge name in the 2 stroke industry, and he explains something that was told to him by his mentor.

 

 

Quote:

My point about first liar in my text the other day is about this very thing. The industry as a whole uses unloaded dynojet numbers to claim their numbers. My two stroke mentor years ago offered this tidbit of advice. He said when developing a new engine package or new product not currently on the market- he said it was important to be the first liar. I asked huh? He said be the first liar- get your numbers out there- whatever they may be. Then you are the first liar. Because anyone else who comes along with a similar product has to lie worse to claim higher numbers. And so on and so on.

 

I know its kind of a funny- but its the truth really. I am in no way condoning outright lying about products- but play in the game with the same set of rules. You arent going to force a paradigm shift in the market by saying that unloaded runs read artificially high and therefore are somewhat to outright invalid. Its not going to happen. So you play the game- you become the first liar- you say ok we did some dyno runs, just like everyone else. With STD dynojet correction factors(a whole nuther discussion about whats wrong there) and 5 smoothing...you're playing by the rules and are not being shady at all in posting those numbers. The guys who go and crank the barometric pressure way up and then withhold the correction factor percentage (anything around 1.0 is considered nominal and not tweaking anything) to get artificially inflated numbers arent playing by the rules nor are being ethical.

 

So where am I going with this. You use the tool. You use the tool to post your numbers in the same manner as everyone is. You use the tool to load the engine in order to get more refined jetting off the dyno, diagnose problems, or develop partial throttle characteristics into your build. Thats all, just use the tool.

 

Another piece of advice my mentor offered was "Run a one story whore house....That way theres no effing overhead...."

 

I know we have a quick bike that accelerates fast off the bottom, and made the guy who built it for himself happy with the way it turned out. I know that you can't compare two different dyno's numbers because not every dyno is the same, and not everyone has them set to run the same with correction factors, and thats regardless of what Windy says, you will never convince me other wise. We compared the same parts on the same dyno for this exact reason. So everyone can see how everything stacked up on the same motor, same day, same dyno, and same conditions. I stand by that I really dont care about the "unloaded" runs we did. I am interested in the loaded numbers because that was puts the closest thing to a real world load on the engine.

 

We made the first run on the dyno Sunday, and the dyno operator turned to me and said, "well Snope what you want to do?" "Chase a number, or tune this thing so it runs the best?" I replied to "tune it so it runs the best."

 

There is a huge difference between the two.

[05stroker]

I will start this off by saying Snope is a good friend of mine and I was skeptical about the pro circuits my self. After we made the pulls and I saw the difference I was shocked. I was half expecting to be looking for some shearer's or cpi's when we got done. After the testing I am keeping what I have.

 

I know we were not able to test the bigger carbs with the cpi's, but I know that Nate McCoy did. If you go over to atvdragracers.com and check out the serval thread in the two stroke tech header, go to the second page and look at that graph. You will see that the red line which is shearer's with stock carbs and reed cages is the same on bottom as the cpi's and shearer's with bigger carbs and v-force 3's (which are the upper two lines). The red line falls off a little on mid/ top but peaks the same hp number. They picked up about 5 hp by putting bigger carbs on at the top of the mid range. Now if you look at my graph with the cpi's it dose not fall as much in the mid range as with stockers. The Pro Circuit's are 4-6 hp more all the way through and they start pulling before the cpi's. It is just speculation, but I don't think that you will pass the pro circuits until the shearer's or cpi's hit around 9,000 rpm. It's going to be an argument unitl somebody has the time and money to put all of these combo's on the same dyno. I am extremely happy with the setup and after looking at Nate's graph with the compairson of the stocker's verse the bigger carb's I feel even better.

 

There is more than one way to skin a cat! This cat got skinned with 28's and pro circuits! (Pun intended)

 

okbeast- This was not a waste of money. I had a 4mil stock cylinder in this bike to begin with. I know it could have been ported more and I could have sqeezed more out of it. I was running 175 psi of compression and running race gas. I know have a serval that is 20-25 more hp and on pump gas. The stock cylinders were probably more of a trail port and Snope was beating me with his ported 350, his bike runs hard. This serval will pay for itself in two years with the cheaper fuel. How can I go wrong. A waste of money would be spending another $1200 to buy new bigger carbs reeds and bigger intakes along with a new set of shearer's or cpi's to get a little more on top.

[okbeast]

Well I don't have anything to post from my mentor's mentor's mentor, so you win

[Snopczynski]

This is the chart 05stroker was talking about from Nate McCoy. On this chart the two lower lines are T5 (blue) with stock carbs and stock reeds. The next line up was Shearers (red) with stock carbs and stock reeds. These were older high rpm shearers that were tested. Then next two lines up are the same shearer pipes along with cpi pipes ran with 38mm pwk carbs and vforce 3 reeds. There is your stock carb vs big carb compariosn chart. Run times would have been usefull on this to see if the smaller carbs accelerated faster than the larger carbs, but as you can see it is a minimal gain. The Pro Circuits were way above the CPI pipes (4-5hp, sometimes up to 9hp more at the bottom, and up to 6hp more at the top.) across the curve on the small carbs with small reeds, so it would still make more power than a bike with CPI pipes, big reeds, and big carbs.

 

For Windy, Nate McCoy said he ran the T5 down so lean to try and get good numbers out of it, that it would never have even been rideable in real world conditions.

 

 

 

 

[WINDYCITYJOHN400]

Comparing your motors "unloaded pulls" to this post you put up of bigger Shearers and bigger carbs. It looks like your curves are stronger from 5500 to 7000, then the shearer/big carb curve kicks in and is top dog from 7000 all the way up to at least 10750.

So your right that your making alot more low end power than the big pipe & carb combo. But it's for a grand total of 1500 total RPM. (5500 to 7000) It looks like the bigger carb and pipe make their power for a total of 3750 total rpm. (7000 to 10750)

Wouldn't that be more than twice the useable powerband of your motor? (I'd really prefer to aslo see the torque numbers)

I understand your trying to get the power in the lower rpm, and congrats, you designed it to do that and it does. But understand that many people would prefer to get the full 3750 RPM of useable powerband over the 1500 RPM useable powerband. So your carb choice might favor the RPM your shooting for, but the bigger carb and pipe would seem to favor anyone who wants "Cub like" peak power with a boatload of added lower RPM torque.

 

Of course it's all irrelevant , because (as you insist) those two dyno curves were done on different dynos at different times with different motors....so it's not even worth the debate.

 

But so far I'm seeing 28's or 38's tried or even stock carbs......maybe 28's are too small and 38's are too big? 34's 35's?

 

Since the stock carb and reed combo is claimed to work so well....why not try stock carbs and stock pipes?

If they made a sleeper serval cylinder, we could all ride bone stock looking bashees that make MAD HP.

 

PS, I would never suggest the T-5's.

I'd say SB shearers and 35's for my guess. But not for the RPM's your shooting for.

Edited March 23, 2011 by Snopczynski

[BigRed350x]

Good post Snop. Good info there. Its what I expected way back in one of the first serval threads.

[Snopczynski]

If Pro circuits opaque CPI's on the loaded dyno runs we did by 4-6 hp on average the entire run with them beating other pipes at up to 9hp down low, then how is it that pro circuits wouldn't beat all these runs on this chart I posted if they were added to the mix and tested as well? The CPI's even with the 38mm carbs would still be under what the pc's were with 28mm carbs if you account for the pc's even following the stock carb and stock intake graph lines for the CPI's for the latest chart posted.

 

From 5,600 rpm to 9,400 rpm the pc's produce more hp than the CPI's did on the loaded chart. How would that not still apply on the McCoy chart with the stock carb, and stock reeds run he did if the pc's had been tested at the same time? As it does apply, that means the PC's with 28mm carbs and stock cages (boyeseen reeds) would pull more hp than even the cpi's and shearers did with 38mm pwk's and vf3 reeds if the curve was on that chart.

 

I guess it looks like my holes in dyno testing with not using the A/F sampling are quickly closing up here. So now that I have shown pc's beat cpi's on a loaded chart, and shown pc's making 80 hp on an unloaded chart. How is that an unloaded chart that shows cpi's at 86.5 hp proves your theory about a bunch of different dynos only ever being off by no more than 3 hp? It looks to me like the Dyno I used is at least 6hp different than the one McCoy uses. Those are considering numbers with 2 mm smaller ROUND SLIDE carbs.

 

Edited March 23, 2011 by Snopczynski

[05stroker]

Windy- Here is the link to Andy from M&M's first dyno run of the serval. Look at his curve as it is closer to my unloaded curve. His also peaks at 80 with cpi's and 34 pj's. It peaks at 8,456 rpm. The pro circuits peaked at a higher rpm than that, a little over 9,000. Andy, I'm not bashing what you did here. I appreciate the amount of work you have done with calvin on these. I am mearly trying to show that we have three different dyno's that show completely different peak numbers with different but similar setups.

 

http://bansheehq.com/forums/index.php?showtopic=134580&st=0

 

Windy- The reason I refered to Nate's sheet was because even with the stock carbs and shearer's the motor peaked the same as with the bigger carbs (86.6 hp). There was just a dip in power (about 3-4 hp between 7,700 to 9,500) between the two different carbs and reeds. I was trying to point out that if you added 3 or even 4 hp to the curve for the cpi's on my graph in that same rpm range you would just hit where the pro circuit's already were. With looking at these three charts it as plain as day that you can not say all these dyno's are with in one horse power. With nearly the same setup Nate's dyno show's 6 more hp than Andy's, and a huge difference in the peak rpm range. The only difference that we know of was the 34 pj's on Andy's and the 38's on Nate's. Nate also said they tried some different domes, I can't find what size dome's or compression it was running.

 

Windy- I appreciate that we have been able to keep this a discussion and not a bashing thread. I know that you and Snop have butted heads in the past over the pro circuits and small carb setups. This is my bike not one of his. Snop has definitely been a big part of helping me get it setup and like I said before I was skeptical at first of the pro circuits. After seeing what it does and seeing how it blew the cpi's away from the bottom to over 9,000 rpms on this particular dyno I can't see changing anything.