When should I put in Piston and Rings?

[CaptainKnobby]

Hey guys!.....When do yall think I should replace the piston and rings in my 06 yz450f. It has 34 hours on it and It has never had the piston and rings refreshed,it still starts great(about the third kick)and the kick starter seems to have pretty good compression. I just checked the valve clearence the other day for the first time since I bought it new and then had my friend that owns the yamaha shop and is also the mechanic to double check the clearence to make sure I was right and the valves were fine......right in spec:thumbsup: . But he said I should put a piston and rings in it soon.........he said yamaha recommends doing it about every15 hours or every fifth race put in rings and every tenth rings and piston:jawdrop: ,That just seems to be to soon for a 4-stroke and for my likings and I thought these four strokes were to be bullet proof. I told him that I seen somewhere they said to do rings and piston at 50-60 hours and replace the timing chain if needed,He said if I were going to do much riding and racing this winter I should do it by atleast september. So guys what do you think? Iam a 30+B rider and race about 15 rounds a year in the Mega Series and right now this weekend is round 10 and was wondering if it needed freshed up by july 10th or just wait till sometime in august.....Like I said it has 34 hours on it,......is that to long to go without replacing rings and piston?

[grayracer513]

When it fails a leak down test.

[642MX]

I freshen mine up once a year. New timing chain, rings, pin, clips, valve springs, and valve seals.

Maybe its too often, but it hasn't let me down yet.......................

[King_Air]

When it fails a leak down test.

This would be the only sure fire way to know the condition of the rings/piston. Any other method is just a guess.

[Captaincautious7]

All thats true, but if you are taking care of your machine and not just abusing the engine by over reving there is no way that bike needs a fresh top end at 34hrs. You need to check out some of the quotes about usable hours by riders on this site. According to what most say,the Yamahas are the most durable 4stroke made.

[ben_suhard]

Your friend should know what's best for a race bike, considering he's a mechanic, and as you know, it's important to freshen up your bike before it blows and costs big bucks. Does he give you cheap rates? Mine's done about 42hrs with no problems, and my previous bike, an '03 KTM525exc had done 90hrs, still going strong.

[Wyatt]

I am at 75hrs of 100% MX riding and racing on my '06. Valves checked often, but have never needed adjustment. No rebuild done yet.

[racerxx276]

I've have 140 hrs on my 06, valves have always been in spec. 1/2 MX -1/2 desert racing , I do change the oil every 2 hrs , runs like a charm, getting an 08 next month....(-;

[eazrider]

I freshen mine up once a year. New timing chain, rings, pin, clips, valve springs, and valve seals.

Maybe its too often, but it hasn't let me down yet.......................

I rode my '04 for 2 years, 15 rear tires, 2 sets chain and sprockets. The valves are still in spec, runs like the hounds of hell......I finally bought an '06, gave the '04 to my son, he is now riding the wheels off it...Go ahead and repla:ride: ce your top end at 30+ hours...Yamaha can use the money to develope that new fangled fuel injection everyone is talking about...?

[btc20mx]

Those are the yamahas I like to hear about, sure they are expensive but damn do they last. I hope my 07 lasts as long as many of yours have. I had an 03 that I sold with over 100 hours that never needed a valve adjustment. I think it has to do with keeping the bike maintained and riding it smoothly but that is the way I ride.

[CaptainKnobby]

Thanks for all the replys...... You guys never fail to let me down!......I cant believe some of the hours yall have on your bikes and have'nt had a top end put in. I guess these yamahas are the stuff......I believe I will give mine the leak down test and take it from there. I might rebuild mine at 50 hr's just to feel safe but was wondering wether to stay with oem piston and rings or try a wisco piston kit. What do you guys think?