2002 HRC CR125R Fonseca with modern twist

Pat327
Posts
686
Joined
2/18/2008
Location
USA
7/1/2026 8:00pm

Sooooooo sick!

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JMCR250
Posts
464
Joined
8/26/2018
Location
Chesterfield, MO, USA
7/2/2026 6:02pm

Beautiful build.  It really turned out nice.

Throw us a bone if you can and post a video of it running!

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matt.3150
Posts
823
Joined
3/20/2015
Location
San Jose, CA, USA
7/25/2026 12:16pm
TxT0RKiT wrote:
What Matt said, its was $43 a gallon last time I bought a can.  MRX02 premixed is a little lean straight out of the can, it...

What Matt said, its was $43 a gallon last time I bought a can.  MRX02 premixed is a little lean straight out of the can, it runs strong and smells the most like a factory race bike in my opinion.  I eventually added some 927 oil to it.  I going to mix MRX02 with T2 for my next test.  This could be the perfect combo.  

Here is straight MRX02 notice not one puff of smoke.  

The reason MRX02 runs lean is because it adds oxygen to it. Giving you more air in essence. So you can run MRX02 straight but will need to put bigger jets in to compensate. It is very finicky with barometric changes so as weather changes and temperature changes jetting changes are needed so it’s really finicky.   When you don’t have fuel that’s oxygenated jetting is more stable. So 50/50 will give you less jetting problems 

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The Shop

8/1/2026 3:07am

Really incredible build, i want to here it! Did you also modify the airbox for a better sealing? Like they did with the RC CR250.

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matt.3150
Posts
823
Joined
3/20/2015
Location
San Jose, CA, USA
8/3/2026 11:34am
BartHonda wrote:

Really incredible build, i want to here it! Did you also modify the airbox for a better sealing? Like they did with the RC CR250.

Used a sealant to help. HRC had a special airbox for the 2002-2004 bikes, but the 05-07 airbox worked better than the HRC 02-04 airbox.  So I just stuck with the 05-07 stock

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