why is my crank rod bearing keep sizing up

[joe420dirt]

why is my crank rod bearing keep sizing up i have put 2 cranks in my blaster and the lower crank rod bearing keeps sizing up i mix my gas like 18 to 1 for brake in i dont get it ?any one no why or how and it only took 5 mins both times to size and it was not over reved?

 

[blaster99]

maybe its your cylinder and piston check that out and make sure that it is the right piston size for the bore,otherwise idk

 

[tjscott]

it sounds most likely that you or someone blew up a piston inside your engine.
now, those pieces are finding their way into your crank bearings

 

[pitkendall]

or maybe those lil transfer port holes in the case halfs are blocked up with gunk but i would think if u put another crank in while u had the case split u would clean whatever junk that was in the crank case out along with the tranny area but thats just what i would do some people dont clean parts as they assemble but id still say check out those lil ports people over look them alot
noone has asked yet if it was a new or used crank maybe if it were used the bearing was already goin bad or the crank was outta true or somethin

 

[89custom]

this isnt for sure, need to confirm it, but isnt it important you do your breakin with the mix (32:1 or whatever) that you will normaly run? ive heard it from 2 people, and 1 is a very good small engine mechanic that does motocross and sleds(my co op)

 

[tjscott]

this isnt for sure, need to confirm it, but isnt it important you do your breakin with the mix (32:1 or whatever) that you will normaly run? ive heard it from 2 people, and 1 is a very good small engine mechanic that does motocross and sleds(my co op)

according to every manual ive read, you need to mix double rich for break in
these parts are brand new and are going to have some friction at high rpms.
and yes, i definitely would check your reed valve to make sure nothing is stopping the mixture from getting through

 

[The Ox]

I would check out to see if you have a bad crank seal. Did you put new ones in. If they have a hole in it from the original blow it will run lean. Also I would run the original mix ratio. People do have a hard time just letting the bike do a real break in.

 

[thefastestkidontheblock]

i also run my jettin a little rich for a break in.

 

[Kennedy_Power]

Are they new cranks or rebuilt?
Run the break-in at 32:1:1
PM me with any questions

 

[89custom]

according to every manual ive read, you need to mix double rich for break in
these parts are brand new and are going to have some friction at high rpms.
and yes, i definitely would check your reed valve to make sure nothing is stopping the mixture from getting through

go ahead and read your manuals but i think ill stick to the advise given by one of the top engine builders in the GTA thats been here for more than 20 years.

 

[tjscott]

go ahead and read your manuals but i think ill stick to the advise given by one of the top engine builders in the GTA thats been here for more than 20 years.

you do understand that people who build race motors build them for performance, not to last for more than a month