Lift v. duration or MegaCycle 330x2 v. Web grind 188?

Hi all, a couple of newb questions,

Recently, we bought our son a nice ‘05 DRZ/KLX125.  After a couple of months of woods/firebreak riding he’d like a little more power.  Been reading through some of the relevant threads here and learned quite a lot about the Suzuki 125-250 engine family and about a bunch of different mods folks have done here. We really can’t justify spending a small fortune on this project, just trying to extend the life of this bike and get the biggest bang for the buck.  

We did the airbox mod, exhaust, just bought an 11:1 Wiesco 61mm piston and waiting on the cylinder to come back from bore/hone.  The high-lift and duration Megacycle 393-00 and the Web grind 213 seem a little much, especially without larger valves, higher compression, bigger carb, and a new CDI to get rid of the rev limiter.  That seems to leave these two cams as the next best for non-racing, enduro type applications.

Megacycle 330x2

Intake lift .358" duration @ 0.040 234° lobe center 100°

Exhaust lift .252" duration @ 0.040 236° lobe center 102°

Intake open/close

17 btc/37 abc

Exhaust open close

40 bbc/16 atc

 

And the Web grind 188 with:

 

Intake/exhaust

Valve Lift (Inch):

0.340

0.340

 

Duration:

270°

270°

 

Duration @ 0.050":

244°

244°

 

Lobe Centers

107°

108°

= 107.5° Overall

Intake opens 15° before TDC, exhaust opens 50° before BDC, intake closes 49° after BDC, exhaust closes 14°after TDC'

                     

The lt230 32mm/28mm valves are reportedly a good fit for the stock 125’s 30mm/26mm valves and help it flow/breath at higher revs and larger displacements than the 143cc here, but requires a larger carb so that's probably not an option.

The Megacycle has greater lift, but less duration than the Web.  Any thoughts if one cam profile is better suited than the other for SE woods?

Thanks in advance for your help.  

Edited by Redfishbluefish

Perfect timing. I've been reading until my brain hurts on this exact topic for the last few days planning for my engine build. My understanding is that more lift = more HP/TQ regardless of engine speed, more duration moves your useable rpm range higher. That would suggest that of your 2 options, the 330x2 would be better for your application. That is likely what I will end up purchasing.

 

But curiosity has my mind wondering, how much is too much? Theoretically the 393-00 should make its power in about the same rpm range but with a lot more lift it should make even more power right? I'm sure that at some point, it won't matter how far the valve is open if the carb/ ports can't flow anymore. I have no idea what kind of cfm these little heads flow, but I wonder at what point does increasing lift no longer increase flow? Assuming there is no mechanical interference, what (if anything) would be the down side of having excessive lift? Assuming stock valves with lots of lift could flow the same as big valves with less lift, would one setup be better for low rpm use over the other?

A big cam will HURT your power unless you have the full package to go with it. From air filter to exhaust, everything needs to work together. Just like those looking to throw a big flat slide on their stock motor, dropping a big cam in a low compression motor will result in low vacuum, and terrible performance. Without getting too much into it, the bigger the cam, the more compression, bigger carbs, a freer flowing exhaust and more than likely a good change in timing. 
This article explains it better than I ever could. 
IMHO, and experience, the LT230S cam is your best bet. I've also had good luck with the early DR200 cam in 150 kitted DRs. 
As for the big valves in an otherwise stock head, you're limited in your flow TO the valves by smaller than optimal ports. I tested stock valve sizes against unported 32/28 and 33/28 in LT185 heads on my 190, and found minimal differences between all three until I was up in the 10K+ range. 

So what cam did you end up going with, and how is it (is it?) running?

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