I just bought an 06 trx 450 ER. It has 75 hours on the hour counter.

With proper maintenance, how long should I expect this engine to last? Assume its ridden fairly hard, and mostly stock with exception of HRC and a pipe. Jetting should be similar to what it was out of the crate.

 

I have lots of friends with 200+ hours on their HRC equipped 06's, and they are all still going strong. Got to say that these machines get frequent oil changes with premium ester synthetic oil (Maxima Extra) and reasonably frequent valve adjustments...and always a clean air fiter (dirt will kill your valves in short order!).

The frequent oil change thing is the most important (go no more than 5 hours)! What did the previous owner do in terms of maintenance?

 

I'm not sure what the previous owner did. He told me he changed the oil every three or four rides, but who knows. I checked the oil and it looked pretty clean. I'm having a local shop check it out right now, upon first inspection they said everything looked good. I was just making sure that I bought a bike with plenty of life left. I'm already planning on changing the oil every 5 hrs or so. I'm used to 2 smokers, so this is all new to me.

 

This engine is the king of Baja endurance racing (both quad and dirt bike). Start it up and ride 1000 miles non-stop! If you aren't on a Honda, you probably won't even finish the race, much less win....

We were originally told stuff like you would need to rebuild evey 15 hours with an HRC kit...which might be true if you are a pro level MX rider, but it's nothing like that for recreational cross country.