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Which Carb?

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Hey, dropped a valve couple years ago, bought a street bike an had my fun, time to get the DRZ going again.

I upgraded to a cylinder works stroker and big bore, have a Yoshi RS 2 and am still trying to find a head in good shape up in Canada but can't yet, may have to buy a new one.

 

My main question is, FCR carb 39 or 41....or what are thoughts on the highly adjustable Lectron carb?

Warren

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I think the consensus is that unless you're stroking it out, you don't need the 41. Never heard of the Lectron swap.

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the 39 is the correct size and carb for the bike .. if you go to something else my opinion is your going to have one gigantic headache trying to tune it right ..

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I called Lectron and talked to them. They said that their focus right now is on two strokes and that while they did have application for 4-strokes like the DRZ they just weren't working on them right now and they were a compromise.

I have a buddy at work with a KTM 2-stroke and he and his buddies all run Lectron carbs. My personal opinion is that now that next year's KTM 2-strokes will be fuel injected, they'll have to focus on the 4-strokes to stay in business.

I have an FCR 39 and my personal opinion is that it's finicky to tune and I've been thinking about switching to the simpler CVK40. However, I'm a novice.

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11 hours ago, Wbevan said:

Hey, dropped a valve couple years ago, bought a street bike an had my fun, time to get the DRZ going again.

I upgraded to a cylinder works stroker and big bore, have a Yoshi RS 2 and am still trying to find a head in good shape up in Canada but can't yet, may have to buy a new one.

 

My main question is, FCR carb 39 or 41....or what are thoughts on the highly adjustable Lectron carb?

Warren

WR450 makes 50hp with a FCR39, but I don't see why a 41 wouldn't work. Lectrons are not for thumpers.

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If you were running big Web cams, over size valves and a Z Pro, 41mm (or larger) would be the way to go to.

You can get FCR'S bored relatively cheaply. Instead of boring to 41 you could split the difference at 40mm.

The DRZ will run cleanly over a huge range of jetting. If you're having issues perhaps the carburetor is junk or you have another underlying issue.

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CVK40 is a bigger BSR, won't have the accel pump punch but is easier to jet and get running right.  Might run out of breathe with stock or E cams, WebCams has some gppd bump sticks.  Jetting will proly be leaner than stock displacement due to the increased displacement. 

FCR needs the flex mixture and quick shot accel pump to make things easier (less carb yo yo's).  Find that used head, good time for over sized one piece valves and a good valve job.

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I have the 41 in mine right now and it's doing fine , had a 39 in it last year but swapped motors out and never really tried them back to back , I don't think there's much to gain with the bigger carb ,I have plans for a big head modding so I went with the 41 for that but till then it's doing just fine . I have a new Lectron for a 4t , I ran it shortly in one of my KLX's and it ran good , just would fit under the tank . I'd sell it for less than what you'd buy one for normally , I likely won't be using it for anything anytime soon .

 

Remember , these bikes are just dual sport bikes , they're not race bikes , your not running lap times , your not competing at some pro level event , there is really way too much effort spent (and $$$) trying to get .05 hp more when 99% can be perfectly happy with the CVK40 and put the saved cash into other things .

 

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Edited by jjktmrider
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6 hours ago, jjktmrider said:

I have the 41 in mine right now and it's doing fine , had a 39 in it last year but swapped motors out and never really tried them back to back , I don't think there's much to gain with the bigger carb ,I have plans for a big head modding so I went with the 41 for that but till then it's doing just fine . I have a new Lectron for a 4t , I ran it shortly in one of my KLX's and it ran good , just would fit under the tank . I'd sell it for less than what you'd buy one for normally , I likely won't be using it for anything anytime soon .

 

Remember , these bikes are just dual sport bikes , they're not race bikes , your not running lap times , your not competing at some pro level event , there is really way too much effort spent (and $$$) trying to get .05 hp more when 99% can be perfectly happy with the CVK40 and put the saved cash into other things .

 

.

Just curious then, I'm planning on throwing a 434 cylinder w/ triple layer gasket, stroker bottom end, act gears, new cams, new valves, and new valve springs. I was originally planning on getting a FCR41 for my setup, but my buddy is offering up a FCR39 slantbody for $200. Am I already too deep to cheap out on getting the slantbody?

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