Fox 25 and 19

[walter weatherford]

How does the newer plain bearing Fox 25 and 19, the ones with the 4 bolt backplate and bolt on venturi compare to the older versions with the three bolt backplate in power and stuntability??

[Just One-eye]

While I cannot claim any experience with a 4-bolt 19, I have experimented some with the BB-shaft 25, and it's not bad, but is neither as sweet-running as the old 3-bolt 25, nor as powerful as the OS Max FP 25.  You can run it in a wet two-stroke setting, but not in a classic 4-2-4. 

[Andrew Hathaway]

From what I can tell, the 3-bolt backplate 25 is a nice smaller stunt engine.  It's very easy to deal with, easily the best of the bunch.  The 3-bolt 19 seems to want to run more a solid 2 with no break, but I've only run the curved baffle version with no venturi restrictor.  The 4 bolt backplate engines seem to be hit and miss.  I've got one late (matte case) 19 that's hard to start and doesn't seem very 4-2-4, but it's never really gotten broken in.  The muffler lug protruding over the venturi is annoying.  I've got another earlier (shiny case) 19 that has really good compression but I've never gotten around to running it.  My 4 bolt 25 feels ok, but again it's never been run.  From what I've seen they run strong, but not really a stunt type run, and a bit weak compared to modern engines.  They're a Fox, so special fuel and treatment are to be expected.

On the subject of the later BB engines, I tried the 19 BB.  With a 9x4 in a solid 2 it pulled a Skyray easily through the full pattern, quite a bit better then a Fox 35.  The 20FP makes more power but the 19BB makes plenty for a sport profile. 

[Clint Ormosen]

While I cannot claim any experience with a 4-bolt 19, I have experimented some with the BB-shaft 25, and it's not bad, but is neither as sweet-running as the old 3-bolt 25, nor as powerful as the OS Max FP 25.  You can run it in a wet two-stroke setting, but not in a classic 4-2-4. 

Have to disagree here. I've found the newer Fox 25BB every bit as powerful as an FP 25 and will rev to a higher RPM. The 19BB has almost as much poop.

But, this post was asking about the Fox bushing 19/25's. Not great powerhouses, but fairly easy starters and user friendly. I dig 'em.

[Marvin Denny]

  Walter, talk to me about them when I get to your contest later this month.  I'll bring the two McCoy thrust washers too.

  Bigiron

[Just One-eye]

Have to disagree here. I've found the newer Fox 25BB every bit as powerful as an FP 25 and will rev to a higher RPM. The 19BB has almost as much poop.

But, this post was asking about the Fox bushing 19/25's. Not great powerhouses, but fairly easy starters and user friendly. I dig 'em.

I don't think he actually said which four bolt Foxes before I responded.  I had a few older full sized Fast Combat models left when contests for Fast began declining and my reflexes had already gone into decline.  I was interested in seeing about the then- new (to me) Speed Limited Combat, and I wanted to get some use from those older models.  That's when I obtained some 25s, 28s, and 32s to try out. 

The Fox 25 BB I bought didn't haul a 500 square inch, 19 Ounce model with the same kind of authority and responsiveness that the FP 25 offered.  I never tried the Fox 19BB, and the Fox bushing engines weren't in the running.  I also wasn't impressed by the Fox being stuck in the old 50's metallurgy (iron piston, steel cylinder).