I`m gonna buy the novarossi N21B 2001BF for my CEn Matrix RTR...I had it with the NX26...way too much trouble for what i paid for...the BF i heard is an awesome motor. hope i get a good one!...should be here next week sometime...will let ya know how it does....novarossi is top of the line . just try it and do the manufacturer`s break-in proceedure...u should be fine...they say u`ll be amazed with this engine...we`ll see...lol....good luck man