moby parma FAIL! (Pics)

So today me and my bro were blasting the beach, and on the way back I was blasting over 50! Then, Bam! no compression.

Got it home, took it apart. Huge hole in the piston!

av7

70cc parma kit

g3 pipe

21mm phbg

42 pilot

needle on leanest setting

88main jet

Seems rich and plugs are black, so why the hole and not seizure? Picks to come in a bit.

Timing?

Re: moby parma FAIL! (Pics)

sounds like it.

Re: moby parma FAIL! (Pics)

detonation

Re: moby parma FAIL! (Pics)

another epic FAIL for the poor moby:.(...

Re: moby parma FAIL! (Pics)

Other french homies have suffered the same demise.

Re: moby parma FAIL! (Pics)

I think I will be going av101 this would need a complete rebuild anyways.

Re: moby parma FAIL! (Pics)

now you've got me worried, i've got almost the same setup 'cept 78 main and CDI

but, i gotta get a better timing tool. right now i'm using a homemade one and i'm afraid the error margin is too great.

Re: moby parma FAIL! (Pics)

I also wonder if it is because I never shaved the top of the piston so that the exhaust port could open all of the way.

Re: moby parma FAIL! (Pics)

hmmm.

It looks like the aluminum is flaked...

See how it failed from the outside on the pick of the underside of the piston crown?

hmmm...

Re: moby parma FAIL! (Pics)

yea the metal is flaked all over

Re: moby parma FAIL! (Pics)

Ultimate lameness...was this on the rigid?

Re: moby parma FAIL! (Pics)

How thick is a new parma crown?

Re: moby parma FAIL! (Pics)

The black 50v

Re: moby parma FAIL! (Pics)

Not sure paul.

Re: moby parma FAIL! (Pics)

Damn that sucks...

Re: moby parma FAIL! (Pics)

***Kim Jong illest*** /

been there, exact same scenario. bummer dude

Re: moby parma FAIL! (Pics)

So why did this happen, did my timing slip What did I do wrong?

Re: moby parma FAIL! (Pics)

We'll be strictly theorizing at this point, but....

Did you ever notice pinging before?

How far advanced were you?

What plug?

Re: moby parma FAIL! (Pics)

stock timing, and a b7hs plug i think....

Re: moby parma FAIL! (Pics)

b7hs, never noticed any pinging. I never touched the timing it was like that when I got it.

Re: moby parma FAIL! (Pics)

King Drunky JCams /

Ouch.

That sucks mang.

What octance fuel do you run?

Re: moby parma FAIL! (Pics)

I was running 93 octane with 50:1 saber synthetic.

Re: moby parma FAIL! (Pics)

***Kim Jong illest*** /

it USUALLY is caused by over advanced timing. mine blew on a timing test run

Re: moby parma FAIL! (Pics)

so, jesse, you gonna go with the parma again or something different?

Re: moby parma FAIL! (Pics)

5% mix... Run the jetting super lean.. follow me kids I might teach ya something :)

Re: moby parma FAIL! (Pics)

Wow, sucks hard. Are you going to get the replacement piston from Treats?

I tuned/broke in my Parma 70 at Bomb Prom. My setup is odd... very rich:

AV7 Parmakit 70

Case Match

Two base gaskets (1.6mm thickness total)

Stock AV7 Head

Beer Can Gasket (leaky, leaving today)

Doppler Endurance Crank

LeoVince pipe

PHBG17

50 Idle

102 Main (!)

Leanest Needle

Malossi Red Filter

2mm BTDC

11/48 Gearing

50+ MPH

It is still not tuned right but I got color on the plug on a very careful plug chop (all WOT) and then proceeded to blast, big time, for 50 miles. I'll tear it down today and look it over but it felt very strong. I can't actually get WOT unless I roll it on slowly as it picks up speed. Plug chop was done this way too.

Re: moby parma FAIL! (Pics)

So you kitted a moped without checking the timing? Lesson learned I guess, but what a total bummer man!

Clean up the sides of the cylinder with some HCl and get a new piston and rings and keep riding!

Re: moby parma FAIL! (Pics)

yes I did! And I should no better, I just wasn't thinking.

Re: moby parma FAIL! (Pics)

do you use a piston stop under high torque for variator or magneto tightening? some of those stops leave dents in soft aluminum

Re: moby parma FAIL! (Pics)

Never used a piston stop on this bike.

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