Yo! My RYCA S40 is about 80lbs lighter than stock, has a jet kit, and a free-flowing intake and exhaust. I'm trying to get a sense of how much of a performance increase I could expect from a VM38, stage 3 cam, and high-compression piston.

I hear a lot of things like "much more torque/feels faster," and I'm sure that's true, but it's there any data that's not from the "butt dyno"? Anyone compare 0-60 or top speed before and after, or have dyno numbers?

In other words, I don't wanna shell out several hundred bucks and spend hours working on the engine for like half a second faster 0-60. I want to get an objective and quantitative answer. Not trying to make a crotch rocket, but I'm looking for enough of a performance increase to justify the cash and time

Thanks!

Yazman, I think this project is just what you are looking for.  It is a ten-part project that starts with a bone-stock LS650 and modifies it in steps, starting from the simplest and cheapest mods and culminates with a big-bore high compression engine.  Complete quantitative data is taken at each stage of modification and compared to previous performance.  Seems to me it's just what you are looking for.  Sorry, no dyno data, prohibitively expensive and time consuming.  But it does record very accurate timed data that conclusively demonstrates performance improvements.

The link will connect you with the last part of the project (Part 10), but it (Part 10) also includes nine links to parts 1 through 9.  I think it will give you a good idea of what to expect.   Have no fear, it won't blow up unless you get carried away like I did.


http://suzukisavage.com/cgi-bin/YaBB.pl?num=1645499584

Do you have to run premium gas with the 94mm high comp piston?

How much performance benefit would a 36/38mm carb and DR650/stage 3 without a high comp piston give? Is it way better to just do all three?

DragBikeMike wrote on 09/16/22 at 17:17:41:


Your data is extremely useful! I went through and added up all the times after each mod you made (e.g., stock = 47 seconds cumulatively for the four RPM pulls you measured, after cam, carb, exhaust, intake = 21 seconds). It seems like air, exhaust, and rejet alone is a 44.6% increase over stock. Adding a cam and bigger carb is a 55.3% increase over stock, flywheel, port, and hi comp 94mm is a 63.4% increase, and going 97mm brings it up to 64%. I know there are other ways to look at these data (e.g., looking at each gear instead), but this gives me a rough idea of whether it's worth it to me.

I'm absolutely astonished that simply opening up the intake and exhaust provides such a huge benefit. It seems to be the most "bang for the buck." I was hoping for how expensive and difficult the bigger carb and cam are, they would give more than just a 10% increase over just intake, exhaust, and jetting. It really does seem like diminishing returns with performance mods.

I have a knack for taking perfectly working things and destroying them in the name of "making them better." I'll think I'll just do the cam chain mod and call it a day!