Genuine Roughhouse Hole in piston

2T4life · Post by **2T4life** » Sat Jul 18, 2015 7:03 pm

Hi everyboy,
I'm new here, but i'll try to keep this informative without getting too long.
I have a 2013 RH50 and have several performance mods done. It only ran for a few hours after doing my performance mods, and here is what happened!!
https://drive.google.com/open?id=0B3jfv ... VZBS1pCNGM

What causes this as I obviously want to get to the root of the problem!

I'll list my current setup:
Hoca 70cc BBK
Hoca Performance Exhaust
Naraku Racing CDI
UNI Pod filter- (properly oiled)
6.5 G Dr. Pulley Sliders
Stock carb upjetted main to 105
CVT is all stock with the exception of the Sliders
Stock spark plug

Ran really well, had a slight rattle at mid-throttle ..didnt sound too unusual so i didnt worry about that too much.

Is this caused by running too lean? Head slap? The Naraku cdi advancing the timing too much?

I made an attempt at doing a plug chop (kill at WOT) and with the 105 jet it was nice and brown.

Here is what my plug looked like after the failure:
https://drive.google.com/open?id=0B3jfv ... VhoSnZKbWs

Cylinder doesnt seemed to be scarred too much..here is what the head looks like:
https://drive.google.com/open?id=0B3jfv ... zFvQm56ZGc

I'd like to know where to head from here. And yes, i know i could go back to stock or get a 150 but let's keep this on-topic please. Any advice would be appreciated!

Thanks!

viney266 · Post by **viney266** » Sun Jul 19, 2015 4:43 am

clean up the head, and re use. MAKE SURE no piston bits got into the bottom end. If so, you gotta clean that up Do you have a picture of the piston? THAT will tell me a lot more.

Also, a rattle is badMkay ?

Take the ignition off for now. Too many things at once. Put it back together with stock ignition and see what we get. Do ignition later

2T4life · Post by **2T4life** » Sun Jul 19, 2015 5:15 am

@viney266
Thanks for the response.
The very first link in my post shows the piston. No scarring or anything just a fairly large hole in the center. I do plan to check the crankcase for pieces before i reassemble everything.

As far as the rattle i couldn't ell if it was the engine or just a loose bolt somewhere!

viney266 · Post by **viney266** » Sun Jul 19, 2015 5:40 am

Sorry, didn't notice first link. DOH!

Thats odd, doesn't look like a melt thru , almost as if something broke it. I would blame the plug, but its not smashed down. Check to make sure thats the right plug for the kit, just for giggles. I am tired, so I will sleep on this one. That IS an odd looikng hole though, not a normal seizure or piston burn thru. They usually look more "melted" or even eaten away, but not like that.
Was there a piece of something in there? A washer or something? check.

That could be timing advanced too much, too.

viney266 · Post by **viney266** » Sun Jul 19, 2015 5:45 am

Also, how are the rings on the exhaust side when you pull off the jug? slight seizing? Heat. check spark plug , but I am still betting on that ignition.

Tired, off to bed.

2T4life · Post by **2T4life** » Tue Jul 21, 2015 12:05 am

Had the chance to pull it completely apart this evening.
There is some little pieces of piston in the crankcase but everything seems ok...any tips on flushing that out thoroughly?

I took some more pics of the piston and cylinder. The guy i bought the parts from is suggesting it's simpy still running too lean..Thoughts??

Here's several pics of the damages. Only had like 2hrs on the engine.

https://app.box.com/s/8dcrdttrjpbf0xdv51t39o5urf2caluk