Are you saying that people are just ''dropping'' in the piston without checking to see if the cylinder needs to be honed or if it has proper clearence???

 

I thought Metal can crack up to a inch beyond what the eye could see and to be exact you need to check it with a special scan ??? How is polishing removing the crack ? Did trinity balance your crank ????

 

RSO that would not surprise me at all. Some shops have a hard time just jetting a carb., and there are people that do it themselves that just don't know.I'm sure many a engine have been put together with someone saying "Yep the piston fits in the hole, I'll just run a dingleberry hone down there and clean up the cylinder"

 

Thanks for the clarification !!

 

SixSixT brought up a point, and since I have the same setup as everyone withthe broken rods, I have a few concerns and a few questions. wshrdskin did you hone/deglaze your cylinder before you assembled it? and from what air said from the cracks in the oil holes, could it be by any chance it just being the oil wasent flown to the top of the rod?, wshrdskin on the big end or little end of the crank look like there was metal to metal contact, kinda like what would happen if a connecting rod bearing went out on the crank? aslo, what oil did you use?

 

CT,

Alba installed my piston, in our discussions theys siad they would hone the cylinder to accomadate the piston.

As for the crank looking as though there was metal to meatal contact, the picture is decieveing. Thats not what that is, that is just the way the crank lobes look They have raised areas that look shiney. The big end bearing is intact and has no play in it. As for oil flow, everytime I change the oil I open the bleed screw on the side of the head and check oil flow. Whether or not enough got to the small end of the rod I have no way of knowing. All my oil passages are free and clear, the oil strainer is free of debris and clear. I am and have always used Yamalube 4 from the day I bought this quad.

 

As a certifired level II inspector for Ultrasonic, Liquid Penetrant and Mag. Particle, I can talk quite abit about Cracks and how to find them.

First you will need to have the rod Magna Flexed this should be done with a WET Florecent method to aircraft standards this will not only reveal any cracks but also impurities in the metal inself. This is for ferros metal Ti will need Liquid Pen done to reveal any cracks.

After you have a good rod than do the machining and cyro balance or any other process. Before you shot peen the rod have it re inspected to ensure that no cracks are there after any machining process. Shot peen and install at that point.

If you have any other questions about how to find Cracks let me know.

Smitty

 

smitty should'nt cryo treating be the last thing done after machining and shot peening and any type of inspections?

 

Plus, shouldn't Yamaha have a quality control along the lines of these types of inspections on items like the CONNECTING ROD?

 

Hey I have another question, What rpm range were you running you motor at, and if at high, for how long? Thought someone brought up that it broke only at the top and I think that would only happen at high rpms with the piston expanding and it seized to the wall and broke the rod. Someone correct me if im wrong.