engine failure- big end bearing

[nickk]

hi all has anyone in australia had they zbox or grubie have engine failure due to big end bearing flying to bits which was caused by chrome hardning coming off of bore and getting fed into bigend bearing
my motor has done only 2500km and i looked into these engine asking all the silly questions about how long will they last and what fails , to which i was told up to 10000km with only a set of rings and nothing fails unless you flog the guts out of it and skimp on the oil you should get good mileage out of it
it does only 15 km a day at around 28-30 kph no rush to get anywhere
thanks nick

 

[Mountainman]

I wonder if that chrome was not put on thick enough ?

that sure is -- not that many miles before -- big time break down

to be honest with you -- have not heard that one should expect 10000 km

from what I have seen around regarding these engines
taking into account that some don't run for long at all
one may expect --- 4,000 miles ??? -- just a guess -- trying to pin this down

get it repaired or a new one so as to -- ride that thing

 

[Pablo]

I'm sure the time to complete failure on the chengine is a pretty wide band range. Just looking and knowing some are put together just a tad differently shows that some may last 2k some.....8k?

I'm not too afraid of mine exploding at this point. Runs well, no strange noises. Point being I don't baby it, just ride as I see fit. WFO is OK as needed.

Good fresh fuel and oil mix, proper carb settings, good exhaust, appropriate spark, and decent cooling and of course (maybe a major thing) matching RPM to conditions.

 

[BSA]

That really sucks, all the more reason for a steel cylinder sleeve.

BSA

 

[screaming emu]

At a pretty good guess....

At a pretty good guess I would say your engine has leaned out too much and has burnt the top end out. This is usually caused by air leaks most commonly the intake manifold from the carby into the barrel. The out come is usually severe loss of power or worst case such as yours, engine seizure. If the bottom end of the motor is ok, best bet is clean the bottom end of your motor out thoroughly and put a complete new top end on. I have a 48cc zbox motor with over 15000kms on it. I changed piston and rings at 10000 and it's still singing to this day. Anybody else out there topped more kms than this on a 48cc? Hope this is helps.

 

[furament]

no ther ****e if not one thing another if time is money im broke for a reason

 

[Fabian]

Engine running tips for long life - 20:1 oil and fuel ratio and stop revving the engine when it starts to noticibly vibrate, generally medium revs.
Get yourself a SickBikeParts Shifter Kit and keep the revs low.

 

[Skyliner70cc]

My long life engine tip: 32 to 50:1 oil ratio but only if you use a castor blended 2 stroke oil. Maxima 927 is ideal to run at 50:1 all day long.

 

[Fabian]

When you are talking "castor oil" you are operating in a totally different ball game - that's some serious lubrication and smells great too.

Even with Castor and continuous wide open throttle use, 32:1 would be on the limits of reliability.

If just cruising around, and no long periods of wide open throttle you would get away with 50:1

 

[linnix13]

well i got over 4000kms on my engine, but any time after 4000kms it was being a pain to keep running, so i would say 4000kms would be a decent lifetime for them,