problem with crankshaft

[guidobetaevo300]

Hello,

on my Beta Evo 300 2 stroke 2012 a bolt came loose and blocked my crankshaft.

The bolt came out my crankshaft itself, we think a production issue,

bad use of locktide product or even no locktide used while crankshaft parts were merged

See picture from the bolt who came loose from the inside of crankshaft

Does anyone had this problem in the past or heared about ?

Thanks

Guido

 

 

Edited December 14, 2017 by guidobetaevo300

[lineaway]

6 year old design problem. I doubt it as I have never heard of it. Does this not hold the plastic block?

[guidobetaevo300]

it holds indeed a plastic or rubber part, the function of it i don't know exactly as the bike is still

at the workshop. the workshop owner had contacted Beta factory but no news till now.

[lineaway]

Did you buy the bike new? Does not look like any severe damage. Were the mains worn out?

[guidobetaevo300]

hello Lineaway,

no nothing is worn out, everything is like new inside

I did bye this bike second hand but trust the seller who owns a Beta workshop

Its the first time he saw this sort of problem in his life :-(

 

 

Edited December 15, 2017 by guidobetaevo300

[peterb]

Buongiorno Guido, most, if not all of the current 2T trial motors use this type of fixing screw to hold a plastic plug in place, to the inner side of each crankshaft flywheel. The flywheels are machined opposite the crank pin to reduce weight there, in order to provide a balancing effect. As the steel is machined away, the volume removed is replaced with the lighter weight plastic so as to maintain maximum primary compression. Bye, Peter B.

[guidobetaevo300]

1 hour ago, peterb said:

Buongiorno Guido, most, if not all of the current 2T trial motors use this type of fixing screw to hold a plastic plug in place, to the inner side of each crankshaft flywheel. The flywheels are machined opposite the crank pin to reduce weight there, in order to provide a balancing effect. As the steel is machined away, the volume removed is replaced with the lighter weight plastic so as to maintain maximum primary compression. Bye, Peter B.

Hello Peter, Thanks for this info, but do you think its normal that one of these screws come loose and start to block and dammage the engine Inside ... ? Did you ever heared about it ?

[lineaway]

 Pretty simple, It`s an old bike now no matter how much time is on it. Either put a new bolt back in with sealant or buy a whole new crank. I just hope my 2016 never does it!

[lineaway]

 I was thinking something exciting happened. Bent the rod at high rpm and put it through the center case while coming up a 20 foot rock face then crashing to your death. Myself I got over the fact that the kick starter sucked on my zero after it impaled me. **** happens. 

[guidobetaevo300]

1 hour ago, lineaway said:

 Pretty simple, It`s an old bike now no matter how much time is on it. Either put a new bolt back in with sealant or buy a whole new crank. I just hope my 2016 never does it!

of corse we'll fix it with a new bolt and new conrod, my question was either the fact that this can happen, and can happen on any model of year i am afraid so

[lineaway]

 Yeah I was wondering how it could come out and not get the rod. Good Luck.

[carlos]

I have heard of one nearly new 2016 300 2t blowing a 2 inch hole out of the top of the engine case on the right side, just under the carb. In that case the dealer sent the engine back to Beta and a new replacement motor was sent back to dealer. Never heard what caused the problem. This is the only one ever heard about out of hundreds of Beta trials bikes sold in Canada over the last twenty or more years.

[guidobetaevo300]

19 minutes ago, carlos said:

I have heard of one nearly new 2016 300 2t blowing a 2 inch hole out of the top of the engine case on the right side, just under the carb. In that case the dealer sent the engine back to Beta and a new replacement motor was sent back to dealer. Never heard what caused the problem. This is the only one ever heard about out of hundreds of Beta trials bikes sold in Canada over the last twenty or more years.

Thank you Carlos, here in Belgium it's also unknown as issue,i cross my fingers

[scifi]

Something not quite mechanically correct here... 

Beta using a bolt to hold a plastic part in place..?   How do they apply a torque to the bolt when it is bearing onto Plastic..?   Surely the plastic will deform over time and the bolt will become loose.

Hope it doesn't happen to mine...!

.

[lineaway]

 Beta started doing the plastic inserts on the later rev 3. I think `07 was the first year. Most everyone uses these now. I am not a fan either, same with sealed main bearings. But I am not going to pull a good motor apart to remove the shields.