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Kehin FCR MX, SmartCarb, or Lectron?


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11 replies to this topic
  • PIERCE.JENS

    TT Newbie

5 posts
Location: Washington

Posted January 11, 2017 - 09:26 AM


I am replacing the carb on my 2002 WR250F. I was going to go with a replacement stock Keihin FCR MX-37 carb (which performed excellently for me previously), but have been attracted by the SmartCarb and Lectron carburetors. My understanding is that the Keihin FCR carb is the epitome of carburetors, but the new technology and simpler SmartCarb and Lectron are very attractive in theory.

 

Any opinions on how they compare?



  • William1
40,331 posts
Location: Virginia
Garage View Garage

Posted January 11, 2017 - 09:29 AM


FCR in a heart beat.

Smart Carb and Lectron are geared more toward a 2S. On a 2S, I'd take a Lectron.

 

 

If you look, you can find near new examples of a FCR-MX 37 for $200.



  • PIERCE.JENS

    TT Newbie

5 posts
Location: Washington

Posted January 11, 2017 - 10:15 AM


FCR in a heart beat.

Smart Carb and Lectron are geared more toward a 2S. On a 2S, I'd take a Lectron.

 

 

If you look, you can find near new examples of a FCR-MX 37 for $200.

Thank you for that.

 

Any tips where to find a MX 37 outside of eBay? I would LOVE to find one for $200, even if it needs to be rebuilt. My current carb is the first gen MX37, I split the body in half and they don't sell mid body gasket kits for the first gen. I am not interested in doctoring a gasket, would rather just replace entirely. 



  • William1
40,331 posts
Location: Virginia
Garage View Garage

Posted January 11, 2017 - 10:16 AM


TT classifieds, Google, Bike bone yard



  • PIERCE.JENS

    TT Newbie

5 posts
Location: Washington

Posted January 11, 2017 - 11:17 AM


TT classifieds, Google, Bike bone yard

I'm on the hunt, thank you!



  • johnnyboy

    TT Bronze Member

420 posts
Location: United Kingdom

Posted January 11, 2017 - 11:19 AM


Have a read and watch of a Lectron review 

 

http://www.cafehusky...e-yzf450.44092/



  • William1
40,331 posts
Location: Virginia
Garage View Garage

Posted January 11, 2017 - 11:27 AM


Have a read and watch of a Lectron review 

 

http://www.cafehusky...e-yzf450.44092/

I just read that thread. That guy never had the FCR set up right, ditto with the Lectron. All engines must use a choke on cold start. If it does not need it, the setting is too rich at idle. Setting up a FCR is a simple, straightforward process. All the ones I have worked on that ran poorly had crazy jetting in them, obviously done by someone who had no idea what they were doing.



  • johnnyboy

    TT Bronze Member

420 posts
Location: United Kingdom

Posted January 11, 2017 - 11:45 AM


I just read that thread. That guy never had the FCR set up right, ditto with the Lectron. All engines must use a choke on cold start. If it does not need it, the setting is too rich at idle. Setting up a FCR is a simple, straightforward process. All the ones I have worked on that ran poorly had crazy jetting in them, obviously done by someone who had no idea what they were doing.

Yep you maybe correct William but there are other people who have had good results with the Lectron on a 4 banger and it is a option if you want something that works well and once set is good for the rest of the bikes days , 

As a side note Kelly who did that review actually designed a few rods for Kevin at Lectron and they all work very well as I have used them all in my Lectrons along with my own grinds. Also he was a seller / stockest of the Lectron so will be a bit biased lol.



  • William1
40,331 posts
Location: Virginia
Garage View Garage

Posted January 11, 2017 - 11:54 AM


Yep you maybe correct William but there are other people who have had good results with the Lectron on a 4 banger and it is a option if you want something that works well and once set is good for the rest of the bikes days , 

As a side note Kelly who did that review actually designed a few rods for Kevin at Lectron and they all work very well as I have used them all in my Lectrons along with my own grinds. Also he was a seller / stockest of the Lectron so will be a bit biased lol.

I've run Lectrons on a 4S and frankly, the FCR is a better carb for them. Kick butt drag racing carbs and 2S carbs though. Just like a round slide is the bees knees on a trials bike. EFI though, blows them all away. I still do not know what all the EFI throttle bodies have butterfly's and not flat slides. I suppose to 'keep something in the bag' later on.

 

To the OP, if you can find a late model Honda FCR, that would be best. I've never tried to fit one though. I say the Honda version as it has a greatly improved AP mechanism.. Fit issues would be the carb bell (the part that fits to the air boot). You'd want to check that before you experiment.


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  • ossagp

    TT Bronze Member

495 posts
Location: Alaska

Posted January 11, 2017 - 11:55 AM


We used Lectrons as well as mikuni vms and tmx's on 4 strokes in the past.  I still have some Lectrons and don't see a visual difference from the newer ones when looking at pictures.  My friend stuck one of the ones he used to have on a tt500 on a 2004 wr250 of his grandson's just to see if it would start up and run.  It did just fine with no changes.  It wasnt ridden that way other than to move it from the shop out to the end of the driveway and back.  

 

I would NOT be considering a swap if a decent FCR was available.  



  • Krannie McKranface
36,659 posts
Location: California
Garage View Garage

Posted January 11, 2017 - 02:08 PM


The big issue with the FCR is setup.

 

They don't come set up for the specific bike they come on, in many cases.

BETA, and some KTM's are an execption.

 

WR's are waaaaay off from Yamaha, being all choked up stock, the bike runs soooo hot you must re-jet once uncorked..... and upgrade the apump system to 2008 specs.

 

A JD jetting kit is a good easy way to do this, but again, the JD needles are generic, and you can do better, and the apump system is not even adressed in the kit.



  • ossagp

    TT Bronze Member

495 posts
Location: Alaska

Posted January 12, 2017 - 01:13 PM


The big issue with the FCR is setup.

 

They don't come set up for the specific bike they come on, in many cases.

BETA, and some KTM's are an execption.

 

WR's are waaaaay off from Yamaha, being all choked up stock, the bike runs soooo hot you must re-jet once uncorked..... and upgrade the apump system to 2008 specs.

 

A JD jetting kit is a good easy way to do this, but again, the JD needles are generic, and you can do better, and the apump system is not even adressed in the kit.

 

I agree,  yamaha and other brands have done things to get bikes offroad approved in the past,   KTM was sending Edelbrock carbed bikes which was another Sparky Edmundson design.  Done right and anyone can do it since there are reems of things written about it the FCR has them all beat for me.   When you find a gummed up one like my friend did (he is 85) he was just curious about what would happen "if".  The FCR is not a clean it up and rebuild it carburetor for a new person to carburetors and the differences from one delivery to the next are pretty wide.   






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