nrg power crank bent?

ill tell you a little secret,it not uncommon for that to happen and its not surprising as the end of a crank is quite long on the transmission side and the metal isnt really that hard there ,i have seen it a few times on peugeot and piaggios and gileras,now you could spend money on a new crank whcih i guess would be around £70.00 for the crank and a garage would charge you about £120 to change it + gaskets, but i have never changed one for that reason ,the trick is to get a copper and hide hammer and take all the variator parts off the crank and take the generator cover off and tap the end of the crank over where its bent with the copper end of the hammer,then spin the crank over and watch the small hole/dent in the middle on the end and see if its spins centrally if it doesnt then knock it the right way until it is.make sure you have the spark plug out or you will struggle to turn it.really its so easy just be gentle and guage how hard you have to hit it to make it move.the only other reason a nrg engine will shake is if the generator rotor is deformed or the crank webs are not ligned up and the webs are twisted on the crank pin if its like this then the crank needs removing and setting straight again with a hammer(copper) and a crank bed and a dti guage.i have done thousands of crank rebuilds .its easy with a bit of patience and experience.once you have suceeded in straightening your crank just put it back together nicely and it will be fine dont wedge it with a lever or something to hold it still while you do the nut up on the end of the crank where the variator is as this is usually what bends them !use a #n impact gun and put some loctite on the threads.good luck with it.

adam bike doctor
February 2010