2 stroke vs 4 stroke engine lifespan

[flyingcr250]

got a '06 KTM 450 EXC, got it at 80 hours and just coming up to 300 hours. ridden pretty easy on trail rides.

up till now only regular maintenance; oil, air filters and valve adjustments every 30-50 hours which i do myself.

last adjustment the intake valves had no adjustment left which is a known thing on this model.

i pick it up tomorrow and i'll be $2k poorer. and thats with me buying the valves and piston off ebay and them doing a few other little bits.

sounds a lot but $2k for 4.5 years and 220 hours worth of fun is probably a pretty good investment.

but gotta admit i was thinking about a 2 stroke or a reliable jap 450 when they quoted $2k just coz the intake valves were gone.

My 2011 ktm 350 blew up last sunday, fucked cams, cam bridge, head, piston and cylinder $4100, and yep im going back to a 2T...

[jt119]

My 2011 ktm 350 blew up last sunday, fucked cams, cam bridge, head, piston and cylinder $4100, and yep im going back to a 2T...

injoy you tube till the bike gets here

[pete.ktm]

My 2011 ktm 350 blew up last sunday, fucked cams, cam bridge, head, piston and cylinder $4100, and yep im going back to a 2T...

damn that was probably going to be my next bike.

but i was going to wait for the 2nd year model.

was there a reason it exploded?

[gammaguy]

If you're talking about road bikes?

Well I've only ever had one top end rebuild including pistons/rings.

But then old Harleys don't need jack-shit in the way of maintenance.

About 4 spark plugs in 100,000km plus oil & filter changes.

Like I said

Bright candles-short

Dim Candles-Long


sir,you have a very long life candle between your knees

[barty5]

Probably an owners manual. And without wishing to seem rude...I wouldn't buy one of your old bikes going by your service history.

there is no point doing piston etc etc if they arnt needed everything measured up fine and oil and filter where always done every 5-6 hrs so dont see the problem.

[Crasherfromwayback]

there is no point doing piston etc etc if they arnt needed everything measured up fine and oil and filter where always done every 5-6 hrs so dont see the problem.

I agree with you 100%. But I think you're extremely lucky getting away with not doing valve adjustments until you got to the hours you state without serious trouble. Dunno if your model YZ has titanium valves or not, but if it has, valve spring replacement is a must too. The titanium valves are so light they get away with running very light valves springs, which lose tension very easily with heat...and can easily fail letting a valve clip the piston.

An RMZ450 (and lets face it, all the Jap brands are very similar) manual will tell you to replace the piston @ 10 hours. Now we all know they're covering their arse by saying so, and it's a total waste of money doing so. But once you get up over 50-60 hours...you're running the guantlet big time in my opinion. But hey...if it works for you, then all good.

Makes my used 450's a good bet for buyers though. As I've never run more than 20 hours on top ends. And I do the oil and filter every single time I ride them.

[Jinxycat]

Ive done over 150+ hours on my 4t and the valves are still well within spec, i usually do pistons aboit every 80 or so hours, frequent oil changes and air filter cleaning will prolong any motors life weather it be 2t or 4t, as for cost, who cares about that??

like to retract that statement??

[flyingcr250]

like to retract that statement??

*hangs his head in shame*

[CRF119]

If you're talking about road bikes?

Well I've only ever had one top end rebuild including pistons/rings.

But then old Harleys don't need jack-shit in the way of maintenance.

About 4 spark plugs in 100,000km plus oil & filter changes.

Road bike engines last much better because the pistons have a much larger skirt and most of its cruising.

Harleys don't ware out because they are decedents from the tractor family

[ding322]

Man you guys are worring me with all the talk of maintenance and rebuild intervals etc so then I did the manly thing and consulted the manual for the RMz and thats just made it worse

Manual states Piston and ring replacement at 12 hour intervals. But that is for top end MX i guess.

[SMOKEU]

Man you guys are worring me with all the talk of maintenance and rebuild intervals etc so then I did the manly thing and consulted the manual for the RMz and thats just made it worse

Manual states Piston and ring replacement at 12 hour intervals. But that is for top end MX i guess.

Yours should do at least 4 times that mileage if you look after it properly.

[motor_mayhem]

I agree with you 100%. But I think you're extremely lucky getting away with not doing valve adjustments until you got to the hours you state without serious trouble. Dunno if your model YZ has titanium valves or not, but if it has, valve spring replacement is a must too. The titanium valves are so light they get away with running very light valves springs, which lose tension very easily with heat...and can easily fail letting a valve clip the piston.

An RMZ450 (and lets face it, all the Jap brands are very similar) manual will tell you to replace the piston @ 10 hours. Now we all know they're covering their arse by saying so, and it's a total waste of money doing so. But once you get up over 50-60 hours...you're running the guantlet big time in my opinion. But hey...if it works for you, then all good.

Makes my used 450's a good bet for buyers though. As I've never run more than 20 hours on top ends. And I do the oil and filter every single time I ride them.

I have an 06 manual thats says do them every 50 hours and I did the one on my 06 450 at 80 hours and it was all good. That's only my experience/sample of 1 though.

It seems very reasonable to put stainless valves in your 450 as honestly has there ever been anyone short of perhaps top level racers who fully utilise the power of them?

[Crasherfromwayback]

It seems very reasonable to put stainless valves in your 450 as honestly has there ever been anyone short of perhaps top level racers who fully utilise the power of them?

I used mine a lot for motard and road racing...so you do have them at full throttle/revs way more than you would in the dirt.

[Crasherfromwayback]

I have an 06 manual thats says do them every 50 hours

I'd be surprised. My '05' manual states every 6 races or 12 hours, as does the '08' book.

[Crabby]

Harleys don't ware out because they are decedents from the tractor family

Concrete Pump family too