Strange vibrations

[carlos fandango]

My RB has developed a strange vibration starting at about 3500 rpm? only started this morning on the way to work but was the same coming back.
Whats the symptoms of a twisted crank ? is there a way to tell if its twisted, apart from taking it out?
It an rb20 which up until now has been very smooth, its the af crank and was checked for true at reedspeed when it was new.
Thanks

Russell

[Andy Pickering]

My brother has just had the same carlos, It turned out to be the big end bearing and crank was fine..

[carlos fandango]

Hi lam
Do you mean the main bearings (drive side and mag side) as the big end is the crank? i dont think its the main as these have only done 2000 miles and were good quality ones.
started stripping top end down tonight to get a look at the crank, but i think i will have to get it out and checked. may get it welded as well for piece of mind as i ve heard that af cranks are prone to twisting.

[Andy Pickering]

Hi lam
Do you mean the main bearings (drive side and mag side) as the big end is the crank? i dont think its the main as these have only done 2000 miles and were good quality ones.
started stripping top end down tonight to get a look at the crank, but i think i will have to get it out and checked. may get it welded as well for piece of mind as i ve heard that af cranks are prone to twisting.

Sorry matey..yes he had drive side and mag done, infact he had a lot replaced as his TS kit had chewed a lot up in 4 years..

Good luck..