Yes I believe you, but how many of them are sold and still running great????!! I hear everytime I go out a 2-stroke has seized. There has been not one trip that I went on (Vacation and Holidays) that I havent seen one not blow up or sieze. 4 strokes are still more reliable than 2 strokes, JMO

I like the power of them but owned too many of them to buy a new one again. Actually, their is two 2-strokes I still own, A Suzuki JR50 and my Chain saw.
[img]i/expressions/face-icon-small-wink.gif[/img]

 

Ya I know 4 strokes are more reliable thats a fact. I still own a 4 joke, My lawn mower. Its lasted years and years and like the rest of em its nice underpowered. [img]i/expressions/face-icon-small-smile.gif[/img]

 

you aren't supposed to talk like that here. this isn't bansheehq and you are going to **** off alot of people saying stuff like that. even if it is true.

 

Ya your right Dabeechman. We built a 50+ RWHP YFZ a couple of weeks ago. Was wicked fast, ran 3.9's in 200ft. Thursday night the piston broke at the wrist pin boss and then it proceeded to put the rod through the cylinder, both cases and the starter.
Our 80hp shee's just need a set of pistons every now and then, LOL
Dynoray

 

On the break in theory, with a NEW engine it should be heat cycled a few times to stabalize the castings.
On a rebuilt engine you still want to heat cycle the piston a few time(especialy Scuff-co pistons) After that we break in ALL our engines in on the dyno at WOT. (after cam breakin on four strokes) We build 175-200 race engines a year and break in is always a compromise. For max performance the top end needs to be broke in hard but it's better to break in bearings and gears with lighter load.

Hey Modquad, what piston was in pudljumpers YFZ? That's what happened to my cutomers with a J.E.
Dynoray

 

sorry, My bad.... dont want anyone mad or anything like that. hahahahahahaha[img]i/expressions/face-icon-small-happy.gif[/img]

 

Just like tekky said is the way i broke mine in. Just make sure it completely warm before you take off, and never keep in pinned for long periods of time. I basically broke mine in like i normally would ride it, just take breaks quicker then normal and change the oil after the first ride.

This isnt the first time ive heard of a yfz blowing up, i think theres more to it then how it was broken in..

 

okay so the word is in the crank bearing went and even though it is past the six month warranty yamaha is still paying for everything...... the yfz is a brand new race bred machine they are bound to have a couple of prob... but hey they are still faster then the 450r.... yamaha will tweak out the little prob. its having and it will be one bad as$ machine yamaha has always been true to its people and ...... look at the shee and the warrior those are too awsome and realiable machines they have been running strong for what 17 years...... by the whay i just got a 01 yz 125 and i love it lots of fun

 

Wow, you got a deal. I wish they would have replaced my one way just after my 6 month warranty.[img]i/expressions/face-icon-small-sad.gif[/img]

 

[quote]
Originally posted by: RaptorOwner
Its not the coating...... Come on. 2-strokes have to have a heat cycle to break in. So, when you buy a car which is a 4 stroke engine I bet you dont drive it over 30 miles an hour the first month right???? LOL!!!! That would be something to see.



You can get most cars up to 65mph without going above 3000rpms. You don't see very many people getting there cars up to peak rpms all the time do you? Engine break-ins are ussually related to rpm's and heat cycles, not vehicle speed.


When I do break-ins i still do heat cycles. I go easy on it the first time starting it, staying at low RPMs for about 30 minutes. Then let it cool take it for another ride for 30 minutes, keeping it at a good amount of rpms, but not hitting any high rpms. After it cools from that I ride a tank of gas not going ***** to the wall, but not babying it. After that tanks done, I go ***** to the wall and ride the snot out of it then let it cool and call it broken in.

Everyone has a diferent method for it, to each his own.