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Discussion Starter #1
I just returned from a dyno tuning session and have some information to share.

But let me start with a quick lead-in. I am preparing an SV-650 race bike for the CMRA endurance racing series. I've been spending a lot of time gathering information from this board and really appreciate the information given here. So I am going to add my modest contribution. :D

When I bought the bike it had already been race prepared for the most part by the previous owner. I have changed a few things myself as well.
The mods are:
Racetech gold valve kit in forks, 20W fork oil
Fox twin clicker rear shock
Exhaust cams replaced with intake cams
Full M4 exhaust
Desnorkeled stock air filter, tank spacers
152.5 main jets, 17.5 pilot jets, one shim under the stock needles
Vortex fairing stay
Sharkskins race bodywork

For this post I want to talk about the engine setup and verify what I have read here before, posted by other racers/tuners. I just returned from some dyno runs and can verify what has been posted before. The way to go IMHO is the cam mod, the jetting exactly as listed above, and the full exhaust. The bike just made 75 HP peak at the wheel on a dyno known to be conservative. Also the mixture was just about perfect for the entire RPM range. The curve was very smooth and builds all the way to the rev limiter, slightly tapering off at about 9500 RPM.

I tried other jetting, and even did a run with K&N pod filters I picked out (they bolt right onto the carburetors). The pod filters actually reduce power output and make the power output curve much rougher. It did lean the engine out (only a tiny bit) but I'll bet if I richened up the mixture to compensate (probably only one jet size richer) it still would have not been any better than the stock air box. I'm racing with the stock airbox and the desnorkeled air filter.

I do not have the plot yet but will post it when I get it. It is only making a little less peak power than my F2 race bike, and has a lot more low and midrange power of course. I cannot wait to get this bike out on the track with some sticky race tires. The first CMRA endurance race is this weekend at Texas World Speedway, a very fast 2.9 mile track with some long knee-dragging high speed turns and long straights.

So, long story short, save yourself a lot of money and skip the jet kit. Just buy the mains and pilot jets at a local shop (less than $20), desnorkel the stock air filter, shim the needles, and spend the money saved on a full exhaust and the cam swap.
 
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ZX-Tex said:
I tried other jetting, and even did a run with K&N pod filters I picked out (they bolt right onto the carburetors). The pod filters actually reduce power output and make the power output curve much rougher. It did lean the engine out (only a tiny bit) but I'll bet if I richened up the mixture to compensate (probably only one jet size richer) it still would have not been any better than the stock air box.
K&N pods need 210-220 main jet.not just one size up :D
 

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Discussion Starter #3
Wow... 210 jets? OK well maybe I'll try them out again :D TWF have you used the pods, and what kind of a power increase did you see? The track I am racing on this weekend has a high speed straight that is long enough to top out the bike so a little more power will shave time there. I've hit 160 MPH on an F2 on that straight. The liter bikes will hit 180 MPH.
 

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OK found it. I have read that article before, forgot that it included pods. Looks like they are not worth much. Thanks again
 

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Discussion Starter #7
I am running it on premium unleaded right now. Race gas might be worth another 1-2 HP but I do not have much experience using that stuff. It is pretty expensive!
 
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Thanks!

Thanks very much for the information on the cam swap and jetting. Nice to get actual results!
 

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Bster13 said:
The Jack Roe Article states to use 2 shims with desnorkeled stock filter...no?

"Fuel screws: 2-1/2 turns out, 17.5 pilots, two shims under the needle clip, 152.5 main jets."

http://www.svrider.com/articles/2001jul_carbs.htm
That sounds about right.

I'm using BMC race filter, full exhaust and cam swap... 165 front & 162.5 rear main jets.

Brad (rivited) is running pods and has ~210 main jets.
 

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BMC race filter, slip-on pipe, cam swap, 160fr & 157.5rr, factory needle on bottom clip +shim = 76hp. (Aust bikes std with 17.5 pilot jets)
 
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