"Catostrophic failure "Broke a valve on ncy racing head  By  geh3333 (Read 770 times)

I'm pretty sure the oil pump stopped working and the scoot overheated . I had oil blowing out of the gear oil breather from getting so hot.

Pics

Finally got to take the engine apart and clean it out. New oil pump but im running the stock bore until i get the chance to order another 60 + kit. Im keeping the same gearing and im going to see how far i can push it with a stock bore. I honestly believe i can hit a true 65 mph and cruise around 60 mph. Its all up to how much HP i can create, so im going to force as much air and fuel possible through this thing and see how she runs . Ill post a few pics 2mro.

Actually dropped both valves .

Just realized i was running 64mm rocker arm assembly with 69mm valves

I'm reading all this and OMG! LMFAO

I told you in the other post you might have been sent the wrong head or rocker arms.
Why did you blow 3 top ends in the same manor back to back??? You do know what the definition of insanity is right?

First things first you need to flush out that engine for debris! There is metal in it, and if you ruin the connecting rob bearing, just go get a new engine or prepare for a total rebuild.

I would do 3 oil changes within 10 miles to make sure it's all out.
Sounds excessive? That's the point...


The valves naturally close over time but heat and high rpm's will greatly accelerate this.

When you upgraded the engine, you needed to upgrade the cooling as well.
High rpm/full throttle runs are good for short bursts, not 80 mile trips. You need some throttle leeway for longevity especially with a bbk.

Throw in some heavier weights to combat your high rpm.

I personally would trash all top end components and start new. You should've done more research before attempting the project.

Even if some of the old parts still work, I'm sure there is damage you can't see that will cause you issues later.

Also, use a heavier weight oil to help with higher temps. Increased heat will thin out your oil reducing its lubricating properties.


Sounds like you just had to learn the hard way and are going to get it right next time.

Those rocker arms and head need to match. Do not try to finesse to get it to work temporarily.
The valves never stay adjusted on these things.
I think the adjustment changed while you rode up to the point of the valve slap.

Unless a valve broke completely off in the cylinder, I also suspect a foreign material got into the combustion chamber.