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Workshop => Engine and Bottom End => Topic started by: Powerstroken on May 09, 2015, 09:52:46 AM
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Well after going to my local mx track this past wed. I have come to the conclusion I want and need more power. My current mods are led full pipe, 38 a/s bored to 39, reeds but am not sure which ones, k&n filter with lid off and coolhead with 19cc dome I have been running 50/50 c12 and 93. It runs pretty good but just not up to par with my old yfz. Now I was kicking around the idea of having Neil port my stock cylinder but started thinking. It is compaired on here often that a ported stock cylinder will run with an esr 310. What I was figuring if I get the esr and have that ported it should really run strong. Does anyone have experience with this and how do they run. Or am I still better off with a ported stock? I have read about the esr cylinders having some issues but they all seem to be posts that are a few years old. So I wasn't sure if it is something they improved on over time. But looking for the better way of making some good power.
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Does your 310 have a pv? The pv is a big help on the 310's.
You have a 310 going smaller cc to oem would be a mistake.
Up compression to race gas only.
You could have yours set up for a 4 mil crank and ported.
You would be better investing in this then an oem and of course there is also the option of going bigger.
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Does your 310 have a pv? The pv is a big help on the 310's.
You have a 310 going smaller cc to oem would be a mistake.
Up compression to race gas only.
Cr ignition.
You could have yours set up for a 4 mil crank.
You would be better investing in this then an oem and of course there is also the option of going bigger.
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No sorry for the confusion. I don't have the esr yet. I was thinking of getting it and Porting it over just porting my current stock cylinder.
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A pv 310 ported and set up with higher compression and race gas is a good option. Are you trying to not split the cases? A bigger bore cyl and 4 mil stroker crank are great options on these R but more mechanical work is required.
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I was not planning on messing with the cases
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This limits options but a lot of guys getting what you can without splitting cases run the bolt on 330. Less long life but you can get 330 without splitting the cases and there is no replacement for displacement. Options for sure.
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Depending on who does your porting and engine setup will determine what you really need. I personally think for mx a very built 330 is a lot to handle. A good 310 runs hard, myself and a friend have motors built by the same builder his is a 250 mine a 310. In a roll on they are extremely close and i pull away slowly, but the touch of extra torque and power is noticable in the acceleration and over all ridability. If your going to invest the money in porting i believe it is smart to start with a new fresh cylinder. Esr price is hard to beat for a starting point. You could also do a 4 mil with eddies new stroker cylinder. Or a cp industries if you have a little extra coin.
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i would think a 50hp 300 would be plenty but then again whats the total weight of bike and rider ? i know a 50hp 2wheeler is a handful on a mx track especially if your a novice rider like myself
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I'm not sure what exactly the bike weighs I am 215 or so plus gear. So I am pretty heavy for motocross I am not looking to go pro or anything just something to mess around with every once and a while. I just try to get a little competitive in any hobby I do just to make it a little more fun. So I'm not trying to build a full blown mx bike and I want more power anyway. I would just like to be up there with the 450s
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I have a drag ported ESR 310 from nate macoy & its a blast. I think you would love a ESR310 pv cylinder & then diffently have Neil port it for mx. It would diffently be a big jump compared to a stock cylinder.
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215 lbs is a lot of weight to make a 310 pull around, especially if you plan to be competitive with built 450 four strokes. The reason a four stroke is so easy to ride is because they have more power coming off the corners.
I can put an engine package together that uses and OEM cylinder and is still under 250cc that will make 50 to 55 peak HP to the rear wheels on my dyno. A 450 with the right pipe, the right stuff done to the head, the right cam and carb will make 50 to 55 peak HP on my dyno. A 450 will make over 50 HP over a 2500 RPM band. A built 250 will make over 50 HP over a 1000 RPM range.
The 450 will come off a corner making around 50 HP where the 250 will start to come off the same corner at the same speed making around 40 HP. If the 450 rider is in the wrong gear, (one gear too high) he can come of the same corner at around 45 HP where the 250 coming off the same corner in one gear too high will be making around 30 HP. Accelerating off the corners well is what wins races not peak HP!
A two stroke needs the added displacement to be able to accelerate off the corners with the 450s.
For you to be competitive with a good running 450 four stroke you are going to need a real good running 330 or larger cylinder that has all of the right stuff in the engine package. Engine packages that will make a lot of power over a wide RPM range are expensive because most guys do not have the right pipe, carb, reeds cylinder, head etc. and need to start from scratch.
If you plan to go this route of building a real good running two stroke, save your money until you can afford to buy/build the whole package at one time, otherwise the results will not be as expected.
Engine building can be compared to cooking. Does someone take a tried and proven recipe with a list of 10 ingredients, go to the store, buy only 7 of the ingredients, take them home, cook them and not be disappointed in the results. Does a customer or cook have the right to complain because he did not think that it really needed the other 3 ingredients or he could not afford the other 3 ingredients at this time?
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I like that analogy. And it does make sense. Like I said I know I'm way to big to even be competitive in motocross 6'-4" 215 is not an ideal size. I might race a few times a year for laughs but mostly I will just be going on practice days to mess around. I realize there is a reason the 450s are dominating now and not 250rs anymore but at this track I am the only 2 stroke and it's pretty cool to be the one who's different on the track. I think anyway. I had a yfz 450 and sold it to get this r. Why u might ask, it's just because I have always wanted an r and in my area they are becoming harder and harder to find. I can always get another 450 somewhere down the road. Right now I am just enjoying what I have always wanted. I know I will never bring home a trophy but just looking to make a nice 50-60 hp if possible and have fun.
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I like that analogy. And it does make sense. Like I said I know I'm way to big to even be competitive in motocross 6'-4" 215 is not an ideal size. I might race a few times a year for laughs but mostly I will just be going on practice days to mess around. I realize there is a reason the 450s are dominating now and not 250rs anymore but at this track I am the only 2 stroke and it's pretty cool to be the one who's different on the track. I think anyway. I had a yfz 450 and sold it to get this r. Why u might ask, it's just because I have always wanted an r and in my area they are becoming harder and harder to find. I can always get another 450 somewhere down the road. Right now I am just enjoying what I have always wanted. I know I will never bring home a trophy but just looking to make a nice 50-60 hp if possible and have fun.
I will go down to the dyno room and get some dyno runs of some different type of engines and post up the graphs.
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Yep, as jerry described and pointed out cc's mean a lot more then some salesman and their mocking birds want you to think. They are just trying to get you to spend your money with them vs the other options you may be looking at. Really consider the idea of splitting the cases before you decide that it is not an option that fits for you at this time. Then look at which directions are available for you to go.
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Transmission ratios are different between the various engines but most transmissions will produce around a 1500 RPM drop between shifts after you get past the 1st to 2nd gear shift.
The following dyno runs are typical examples of engine packages and engine builds that may not have all of the components working together.
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Thank you for posting those. I was always kind of confused when people talked about useable horse power and those show exactly what it means. I guess that's exactly why the 450s dominate now haha. Well I don't have the money right now to start any of this project but I am planning in advance and picking your experienced brains. I appreciate all the info so far.
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I agree 100% with waiting until you have all your ducks in a row before starting the build. Get everything done right the first time and you'll have a much better experience
I'm right up there in weight with you at about 235lbs. I went with a 350 and I love it.
If you go with the ESR, you can now buy them in the proper length (no spacer plate needed). I know this is how LED builds them, but i'm not sure if you can order them directly from ESR. Might be an LED specific thing.
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I can tell you from experience, especially being a heavier ride (220), that even a ported 310 will not allow you to run off and leave the 450's. I ran a ported 310pv for the last 2 years. It allowed me to keep up with the 450's, but not blow by then. So it really just depends on what your expectations are. If you just want something for fun that will keep up, go with a 310 ported by Neil like you mentioned, I think. If you are wanting to beat them or be at the head of the pack, then you need no less than a 330 if not larger, and consider stroking it.
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If you go with the ESR, you can now buy them in the proper length (no spacer plate needed). I know this is how LED builds them, but i'm not sure if you can order them directly from ESR. Might be an LED specific thing.
fyi= What Tbone is referring to is that they are now making the top of the cyl taller to your specs so there is no dome mod needed for most stroker builds. They cant make them at this time have more material on the bottom to eliminate a spacer when needed.