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Question Regarding Carbs & Mods

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I have a quick question regarding carb adjustments when making modifications.  Sorry to take up a whole new thread for something that has most likely been stated a thousand times before, but I couldnt quite find the answer to my question (or wasn't sure exactly what phrase to search for to find my answer). 

 

I am wondering what modifications require the carb to be adjusted/rejetted.  I assumed anything dealing with the exhaust or intake, and im assuming if you jump to a stage 1 cam or do the big bore kit as well.  However, I really want to rip that stupid smog crap off my bike because it looks horrendous. If i rip that off, do i need to make any carb adjustments or will stock form be fine?

 

In the event I do have to fiddle with the carb, is it really that difficult or does it simply require getting some new jets and testing them one at a time until it seems to run right? I really don't know anything about carbs that are more complicated than what you'd find on a briggs and stratton. 

 

Actually... One more question since im starting a new thread anyway - Is there any big bore kit that can be purchased and ran on pump gas? They all seem to be pretty high compression but id like to get something to run on 91, since even 93 isnt all that common around here. 

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search daves mods.

 

Are dave's mods needed for the bike to run right after desmogging it? Id like to rip off the smog stuff without having to make other adjustments if possible. 

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Just removing the smog stuff doesn't really affect the mixture.  But the factory jetting is on the lean side, so going to a bigger jet and moving the metering needle up a little bit will make the bike run better all by itself.

 

Opening up the airbox does more in the way of requiring richer jets than anything else you do to the bike.  A pipe comes next, then cam changes.

 

A few months after I got my XR650L, I bought a Factory Pro jet kit, which came with four main jets, a new pilot jet, and a needle with five clip positions to make it easy to adjust.  If I had bought all of those parts separately, the cost would have been similar.  But you probably only need two main jets, a 155 and a 158 to get the bike jetted properly.

There is a link to Daves Mod in the FAQ at the top of the XR600/650 page: http://www.thumpertalk.com/topic/565810-faq/

 

Following the Factory Pro instructions was pretty much the same as what is suggested there, except not bothering to drill the slide.  I didn't want to make any changes that I couldn't undo, so I'm willing to live with slightly slower throttle response.

 

The bottom line is that you don't need to do anything to the carburetor if you remove the smog stuff.  But rejetting will make it run better, so consider doing it.

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The big black thing near the petcock isn't smog equip, BTW, it traps oil vapors. If you tun that hose straight to the airbox t may dump some oily carp in there.

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The big black thing near the petcock isn't smog equip, BTW, it traps oil vapors. If you tun that hose straight to the airbox t may dump some oily carp in there.

Mine runs straight to the airbox, but I've never seen any carp in there. ;)

 

Sometimes theres a bit of oily film, though.

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