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natebal

pipe dreams?

7 posts in this topic

Ok, now that I've done some research on potentially moding my '02 650L I'm pretty sure all the jetting/slide drilling/ needle shiming/ airbox opening shinanigans are pretty much not worth doing without opening up the exhaust as well. I've read a lot about Daves mods and know that he runs a stock exhaust, but this confuses me. Looking at the directions for doing this mod, it seems a lot of effort to do if not also opening up the exhaust. Yet someone with the skills to yank the carb and do all this and motivation for a faster smoother accellerating bike doesn't add an aftedrmarket pipe?Is the stock pipe less a culprit of the lean stock condition than the jets and air intake? I could buy this yet for all the disscussion of brandname pipes in particular.Guys describe different pipes as being stronger in low, low mid, top end etc. Can a pipe alone effect powerband at different rpm with all other things being equal? this seems weird if "daves mod dave" is happy with a stock exhaust. Isn't ann exhaust pipe essentialy just a coffee can with different amounts and shape of baffle? I could understand if we were talking about a bigger header pipe diameter or just an overall opening effect with a bigger pipe but different types of powergains in the power band just from the brand of pipe, sounds a little fishy?

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The biggest difference I noticed from the mods is the throttle response. And that was accomplished by drilling the slide and shimming the needle. I didn't have the jets when I did the drilling and didn't remove the snorkel until I had the new jets. And I had the stock pipe on at the time. When I changed to a Supertrapp IDS2 w/ quiet core it didn't seem to make much of a difference.

As far as different pipes go, the basic rule is less backpressure helps top end and more backpressure increases bottom end. Since different pipes have different designs with different backpressure, it makes sense that different pipes would make power in different rpm ranges.

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The bike comes set too lean. The mods address that problem. It will run better after the changes, pipe or no pipe. Drilling the slide, allows for the slide to open quicker, helping throttle response.

There used to be aftermarket baffels that were available. That gives a much better flowing exhaust , without the cost of a whole new pipe. I have one in my XR600 and it made a huge difference.

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Thanks, so the guys talking about feeling the difference between one pipe and another with all else being equal are just on glue I guess? Or just wishfull thinking? I could maybe see there being a detectable difference in power associated with different brandname pipes, and without a doubt a diff. in acoustic properties, but one giving more low end power while another more mid? Is this for real?

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It's for real, especially the one with disks. Typically less disks give a better mid to high end and more disks give better low end. There is not a hugh difference and the stock pipe actually flows pretty good. My WB E-series was not much lighter than the stock can, so not much for weight savings either. Also smaller headpipe diameter shoud give better low end. I did grind out the welds some in the inlet flanges, you can gain some flow there.

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My XR650R really likes the more open aftermarket pipes. I've tried several, including the fully stock fully corked pipe. Overall power isn't so much different, it's the throttle response, which is much more important than a few HP. The quiet pipes just kill my throttle response no matter how the carb is jetted. The WB E-series pipe (Pro Meg version with 6 or more discs) allows me to have nearly perfect throttle response. I really prefer the quieter pipes, but the throttle response is worth the tradeoff to me.

However, if you can get your 650L to run good (throttle response) with with the carb mods and the quiet stock pipe, then you have the PERFECT combination and definitely stick with it.

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Thanks, It works pretty good as is. No use thowing money at it until I need to I guess. It's kinda like a boat, You don't need to go looking for ways to spend money, that stuff comes after you pretty quick without trying. My basic take on it is run the original stuff til it breaks then buy the best replacment parts. Good to know the pipe characteristcs though, again thanks Nate

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