Top ends hours?

[bowhunter11199]

Looking at buying used 450’s that range from 30-100 hours. All different brand but let’s say Yamaha for now.

when should one look at doing a top end? And how much would a dealership (let say Yamaha) likely charge assuming no damage to other parts of the motor?

 

[dooman92]

bowhunter, lots of variables to consider. low elevation dusty conditions wears/fatigues faster. greater cylinder pressure working on piston and dirtier air. high elevation cleaner air less piston stress unless consistently operated at high rpm. I've had a 510 husky and a 500 ktm with both over 300 hrs on the snow. They are both running strong approaching 400 hrs each. On my Yami 450 I changed piston at 200 hours (all on snow, mostly high elevation, and it was in excellent shape. I sold that bike with close to 200 hours on that replaced oem piston and that bike is still running on dirt. Like miles on an engine, hours are just one of the factors in engine wear/fatigue. Oil changes and consistent temp operation also have big affect on longevity. Long story long, if buying used from an older rider who never hits rev limiter don't be afraid of 100 hours. If buying from his younger more aggressive partner who hits rev limiter every ride change piston at 100 hrs. Hope this helps.

 

[needpowder]

I agree with Dooman. I personally feel that snow biking is way less hard on race bikes then dirt riding. I understand they are ridden at high RPM‘s often but I don’t think it really matters. Personally, i usually look for a 5 to 10 hour type bike that somebody really never rode. Typically I change my piston at about 100 hours and change my oil way too often, but I will go less or more hrs depending on where I end up at the end of the season. I am a Yamaha guy and buy a cylinder works (vertex) mathched cylinder/piston/gasket replacement top end kit. About US$600 . Find a good shop—not a dealer to throw it in and it will probably cost about200- 300 or so in labor so you’re about 1000 out the door. Don’t forget to get a OEM timing chain for them to put in also. Might have to replace a few clutch components at that time as well. I wouldn’t be afraid to run a 30 to 50 hour bike if I knew the history as far as maintenance/oil changes/operating temperature.

 

[byeatts]

We have pulled down snow and dirt bikes, interesting the snow builds that were run very hard ,wide open most their life show little wear on the piston at 160 hrs, no dust and running wide open seams to apply less Piston rock then lugging and chugging a motor. I will go another 160 before changing however I have a race high comp 470 top end here to try with high rev cam , RP exhaust ,Airforce intake and fully ported head and of course the Vortex custom Map.

 

[norsepeak]

I just pulled my '14 KTM apart with 270 hrs on stock piston etc. Everything looked fantastic still. The bike has been a snowbike it's whole life. Last summer I went thru my '16 Husky 501 with over 400 hours and same thing, looked fantastic. I think if you run good quality oil and make sure everything is good shape often, you can go a long time on these bikes.