I do believe your correct....mine looked pretty worn...another good hard month on it and I'm sure it would have went....Just can't figure out why it's only on the right side
[img]i/expressions/face-icon-small-confused.gif[/img]

 

MasterRaptor to many top engine builders I know stay away from them. There is a reason for that!

The stock Raptor rod that came out of my engine looked good but once measured it was .005 out of round and half of the wrist pin area had gawlding marks. It was a 12:1 JE piston (stock bore) and a stage two Hot Cams. I only ran that combo for about six months with maybe 10 hour on it..........

 

Dont scare me ernie!

 

I ran the ***** off my CR686, high compression and stock rod. It had about 40 gallons of fuel (MX) through it when I sold it to a guy that used it for XC racing. I used synthetic oil, Mobil 1 and Amsoil. Maybe I got lucky?

 

Could detonation cause some of these failures? Maybe from not using high enough grade of fuel. I know for a fact that some gas stations premium fuel is a mix of whatever fuel the tanker puts in there. (Chevron, too guys) Alot of times the 93 octane is diluted down.

 

In a domed piston case and larger bore it is the added weight of the piston. Even a few extra grams can cause problems in this area. To illustrate this point, punch the air as hard as you can. Doen't feel too good on the elbow and shoulder does it? Now grab anything heavy that you can hold in your hand. Now take a punch in the air. After you get out of the hospital you will be able to see the difference I think. [img]i/expressions/face-icon-small-happy.gif[/img]
Now, your piston is going, what; 50, 100,? times the speed of your hand?? That's what pulls rods in half. Rods fail on extention, not compression. That's why you want the lightest piston you can get if you buzz the bajesus out of your engine. The higher the RPM, the more stress the rod see's.
So you can see if you put a high compression piston (heavy) in your quad and want to buzz it up to make more HP, you are going to have some problems with a weak rod from the factory.

 

UBETRUN, I love the way your Raptor looks, like a mini pro street ready for flight![img]i/expressions/face-icon-small-wink.gif[/img]


XxDumontRaptorxX this is my only experience with the stock rod, and whos to say it was not already distorted when I bought the raptor! I have since then built two other 686 for friends of mine using stock rods in both and they are still running fine. Sorry did not mean to scare anyone.

 

Synthetics are superior lubricants compared to traditional petroleum oils. So to blame the failure on the oil is probably a little unfair to say the least. Sounds like Yamaha may have a little engineering redesigning to do on the Raptor rods. I've got an 89 Warrior that has always run synthetic oil and it has never been rebuilt, doesn't leak oil, doesn't burn oil, and never have to add oil between changes. So that has to say something for synthetics or the engineering of the Warrior motor, or both!

 

I compared my stock piston with the new Wiesco 11:1, 2mm over before I installed it. It was noticably lighter than the stock one. So, If that's the case, I should be OK.

The JE pistons and others must be heavier than stock?

 

RaptorOwner,

Were you hauln' A$$ when you're engine grenaded? Or were you on a Sunday drive?