Serveta 200 with a snapped crank, ooops :-(

[TED CRUD]

happened to chinky Phil on his GP a few years back, peppered everyone behind with shrapnel.

Granty done one as well GE

[Adam_Winstone]

No, mine had the back of the big end eye break away, allowing the piston and rod to smash up against the head, whilst the rest shot out of the back of the casing. It appears as though mine cracked from the corner of the lubrication slot that is cut into the big end eye.

I have done thousands of reliable miles on MEC race cranks so I cannot instantly discount them.

Adam

[lambro]

787 views, only 2 feedbacks on it happening on this make, and one of them was because of shimming the top as well.

I also have a Mec crank and have done about 12000 miles, hard riding over the last 4 years (using garage forecourt 2 stroke and the 'splash' measuring technique, rather than that messy jug) and have had no complaints.

Hopefully we will get an update as and when Servetta200 strips it further and reports back on any other findings.


Shaun.

[soullad]

this happened to me on a jet ski about 20yrs ago in my haste to get out on it I forgot to put 2stroke in but f%%k it flew for a few min's well impressed en

looking at the pics that was my initial thought. I'm not saying that there wasn't any 2T present but maybe theres a fuel / oil issue here, not a crank one? Be good to know when / what oil / ratios / fuel used etc prior to this crank failure.
Of course there could just be a design fault or manufacturing reason for this, but I'd have thought we'd have seen far more failures if this was the case, there must be 1000's in use out there in the hands of the public, being used and abused everyday.

[Servetta200]

Thanks for your thoughts guys.
When the scoot blew i had just left the services and gone about 10 miles.
I have a 17 litre tank and topped up with 5 litres of unleaded with a 3% fully synthetic rock oil mix.
I have noticed Rock oil has now changed colour from a redish colour to blue, anyone know why?.
I work for a engineering company where we have a scope which can magnify surface materails by a thousand of times.
So I'm will use it to look at the small end part of the rod to see if the crank was fracturing before it final broke.
I should be able to tell this by the surface structure images from the scope.
I'll post them next week.
Believe it or not i'm going to have a go at repairing the casing using a donor engine.
Working for a engineering company has its good points.
I'm told it may be possible to repair the barrel as well which i thought was definitely scrapped.
I'm taking it to a mates tomorrow nights to see if he can spot anything I haven't which might have caused it, he builds and restores scooters for a job.
After talking to many people I will still use the same make crank again to rebuild the new engine as every thing points to this being a one off. I think Mec have a new crank out with a polished rod which is meant to be stronger.

[psychedelicropcircle]

The rock oil colour change is red is auto lube and the blue is premix. I'd avoid mec as they went bust and if you have a duff one no one will replace it.

[a.j]

that looks nasty mate..

as an aside, what should the life of a crank be, mileage wise?

[lambro]

I'd avoid mec as they went bust and if you have a duff one no one will replace it.

Not sure any dealer will replace a crank under warranty after being fitted and run for 2 years would they??
Even the gone bust dealers that still trade may draw the line after a 2 year running in period.

[dennis]

Ahwell, looks like it's back to the good old standard SIL cranks.

[coaster]

After talking to many people I will still use the same make crank again to rebuild the new engine as every thing points to this being a one off. I think Mec have a new crank out with a polished rod which is meant to be stronger.

I take it the crank webs are undamaged? if so, your best bet would be to take it somewhere like MB and get them to fit a Yamaha rod. I Had mine done locally earlier this year at CS Engineering in Norwich, I supplied the rod which came from Yambits complete with big end bearing and shims for around £35. That way you will have a crank that you KNOW will be reliable.