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kk21

2016 YZ 450F Head gasket oil leak

9 posts in this topic

Quick run down.

Severe hydro lock resulting in bent rod.

Tear down and rebuild with hot rods crankshaft assembly and vertex hi comp piston kit. (14:1)

Two rides later coolant is burning off rapidly. Half or so in 20 min of hard riding. Could see white film on exhast. No oil loss.

Tear down replace head gasket with new oem again. Torque to manual specs very very carefully again.

Second ride and oil is leaking through head gasket on right side between case and barrel.

Need some help.... 

thinking warpage from losing coolant and overheating during the first go round or case needs milled along with barrel???

Any ideas???

 

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did you check the specks on head gasket itself? just wondering if your ran torque specs off the manual for the bike or off specks for the gasket

Edited by craig.murray

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also the comp ratio on the 16 was 12.5 - 1 if i remember correctly so maybe just maybe need er a little tighter running 14-1 but im spitballing ideas before i think about milling

.

Edited by craig.murray

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Gasket kit used was stock yamaha oem. Therefore i assume torque spes would not differ from yamaha service manual.

Also as for the additional compression, it should be confined to the cylinder and not affect the aforementioned gasket. Possibly the gasket between barrel and head however the leak is between barrel and case. This is my understanding anyway....

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Gasket kit used was stock yamaha oem. Therefore i assume torque spes would not differ from yamaha service manual.

Also as for the additional compression, it should be confined to the cylinder and not affect the aforementioned gasket. Possibly the gasket between barrel and head however the leak is between barrel and case. This is my understanding anyway....

 

The torque would not vary regardless of the gasket used.

 

The additional compression pales in the face of the combustion pressures that the engine produces, however, and the pressure is most definitely applied not only to the cylinder, but the head AND gasket, and every other thing in the combustion chamber.

 

The "head gasket" you are talking about, between the case and the cylinder is the BASE gasket, not the head gasket.  There is, on the right side of the cylinder deck on the crankcase, a high pressure oil delivery passage, which is the likely source of your leak, which may be the result of a damaged gasket, inadequate cleanup of old gasket debris, or some other improper assembly.

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Thanks grayracer. I will order and install, with great attention to detail, a new oem gasket kit and report back my experience.

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To follow up here. I was mistaken on where the oil was originating. Further detailed inspection showed oil coming out weep hole. I was baffled by this initially. After pulling the valve cover i found a split in this gasket on the inner ring that goes around the spark plug hole. Problem solved!

Lesson learned

Determine exactly where leak is originating, a miss diagnosis here caused a wild goose chase and much grief!

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