Maintenance & Technical > KX450F / KX250F
KX450F vs. KX500
Texas Champ.:
Don ; The post prior to yours replace the head...over $1000.00 , no piston, rod, crank, and labor. Don I didn't register on this forum to come on here and lie....If I don't know,I don't reply.
The people who I know that have had these problems change there oil often ( some every ride ! ) . It maybe that it's hotter here than where you live ( left blank-no entry) Your quite fortunate that you can change a piston or crank. most mx Dad's can't do that. , so they have to pay a shop to do the work and it adds up.
2 stks. are competitive. Mike Clement ( 6 time Vet. World Champion ) does it on a 2 stroke , the guys trying to stay up with him are on the limiter and constantly winging the clutch.....km
don46:
I'm not syaing your lying, I'm trying to understand, by your account, every 35-70 hrs you must shell out $3000-3500, lets be real, if that was the case the manuf. wouldn't sell 4 strokes, there would be a revolt. Sorry to say, I still believe it goes back to the person riding/maintaining the bike. On the MX track a 2t can be competitive in a very few circumstances, very few, for example a very tacky track with an abundance of ruts, on a hard slick track no way. Sadly, look at the starting line at the Supercross races or last year at the nationals, if a 2t was good you'd see more of them on the starting gate. If everybody went back to 2t , I'd be right in line, but at this time to be competitive you've got to have a 4t, bottom line. On the KXf there is no adjustment on the compression release, the cam chain is automatic.
Yes there are things that are more of a pain on the 4t, you won't get any disagreement from me on those points. I'm saying no way that kinda dough for a rebuild and that the 2t is not competitive with the 4t on the MX track. You seem to believe that without a doubt the 4t is going to blow at 35-70 hrs and when it does it will totally destroy the motor, no sorry not seeing it, i've seen busted pistons that did no damage to the motor other than the piston. But hey, believe what you may.
bigbellybob:
--- Quote --- i've seen busted pistons that did no damage to the motor other than the piston.
--- End quote ---
how much did the new piston cost? where did the peaces of the piston go? how did that not damage other things in the motor? how can the rod go up and down with no piston and not damage something? this is hard to believe.
as the rules change the 2t will become more competitive. the 4t has just had to grate of an advantage. yes a motor that is babied will last longer than one that is hammered on. but racing is the hardest thing you can do to a bike. the 4t is definitely more expensive, they cost more to buy and cost more to maintain and really cost more to rebuild.
KXcam22:
Easy on the words there boys. This is all very interresting. I am a new 4-stroke owner and I am not worried. I recognize that this bike will not take neglect like my K5, but then I am a fine mechanic and have never neglected a bike yet. I expect at least 100 hrs or more between valve adjustments. Many get this. If I was back racing it would be less. About the only difference between my K5 routine is the more frequent oil changes but even that is blown a bit out of proportion by some. From what I read some change their oil every ride. My manual suggests 15 hours - I am going to hedge my bets by going 15 hours but running good synthetic. I did have to add an hour meter, which is probably a good thing to have on any bike. Keep the air filter clean and I have no worries.
I can understand that the new 4-strokes aren't for everybody. I have only ridden the bike a few time but already I can tell (other than the newer ergos and suspension) that the 4-stroke power characteristics allow me to put more tractible power the ground (which is the part that counts) that anything I have been on. I think a good example to look at is supercross; tight tracks make me think that light bike weight would be king (as in 2-stroke) but even the privateers are riding 4-strokes for the acceleration/traction factor to clear the jumps with short in-runs. I am sure reapir costs can be astronomical for a grenaded 450 but the same goes for a 2-stroke if you snap a rod and whindmill it through the cases. It is my opinion that for someone who must take his dirt bike to the dealer for maintenance, then a 4-stroke is not for them. I was eavesdropping at my local dealer, and he quoted a guy $400 for brake bleeding and some other misc work - and he wasn't out of line - just the number of hours required at their shop rate. I also notice that many dealers steer customers onto these bikes knowing that they can't maintain them properly. On the flip side I have also seen dealers recommending lawnmower quality 2-cycle oil to owners of new high performance 2-strokes (KX85's), both somewhat underhanded practises.
I have to support Don on the shattered piston thing. I have had that happen to me a number of times where it caused no other damage. I once blew a cam ball-bearing on a 4-stroke 500, took off the sump and managed to reassemble the broken bearing cage parts until I had found them all, replaced the bearing and off to the races - no other damage (yea I was lucky).
I know everyone has opinions and has "heard" about some ugly costs and rebuilds but I like to talk directly to the guys who ride em and race em for some real evidence. So far I think this bike is going to be great and last a long time, but who knows. Maybe in a few years I will be looking for a K5 engine to shoehorn in there while my wife plants flowers in whats left of the 450 engine. But for now I am going to wheelie away with a grin. Cam.
puffy:
I agree with alot that is being said .But 40 to 70 hours until a rebuild is no way true. But 3000 grand for just parts to rebuild a 4 stroke is a minimum.Every one I know says if you can do it for that your lucky.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version