Oil seal ripped in half + idle needs LOTS of air.

[Blaze_Fox89]

i have plenty of nice things to say, i've just run out of nice things to say about zbox's. Anyhoo, grubee 66cc's work perfectly now, the gen 1-3 motors were prone to shattering their rod bearings but the new ones are flawless, makes me wonder why i switched. it was the grubee 66cc that i got to hit 92k's an hour. I think the problem is slightly cheaper metal and it has gotten cheaper now so it warps like crazy. if it was just my motor it would be fine and i'd shut up but it's 13 separate engines and counting that are unseal-able. i had someone offer me another one with the same problems the other day.

There faygo union motors btw. i'll check the squareness of the case later on in the year.

 

[Blaze_Fox89]

Thunder Update:

I checked the crank cases on 2 motors I got a hold of and mine and they are sealing ok, just the intake flanges are severely warped but nothing unfoxable.

My problem turned out to be a leaky headgasket that was leaking back into the crank case, making it run like it's rich and stall like an air leak (I checked it but there must have been something else wrong at the time). It still runs a bit rough and leaks air like a sive but it works well, I can probably recommend them now, but if it ever gets too hot, expect to have problems. They also sell rusty spare blocks and other things but their warranty covers that.

So if you have a /dead zbox or an intake leak on something else, modern glass and what, 230-250 sandpaper? And you should be going again.

The oil seals are holding well, even past 10k+rpm with no covers so this motor is shaping up well, finally.

Apologies for the long semi-off-topic posts but this problem seems to happen to a lot of people (lean-like running with a black spark plug), so hopefully all this helps someone somewhat.

 

[Al.Fisherman]

Milling the head is high on my list of things to after unpacking the engine...along with others. Been recommending it for the past 3 years.

 

[Blaze_Fox89]

The grubee and zbox motors have very good head seals to begin with so milling them would probably be bad as they have groves that bite into the seal, but cheaper ones definitely. This leak was caused by a de-threaded nut, but leaking internally. I'd definitely mill the zbox intake face and manifold though, they are all bad. The Grubee GTx's don't usually need anything done but the cheaper ones will probably need it.