crank walk?

[andyfiggy]

my scooter kept cutting out the other day & was difficult to start but after many kick starts i managed to get home (the problem turned out to be a weak & intermitant spark from the pulse generator after going through flood water)
however in trying to get home ive created a new problem by being over enthusiastic with the kickstart & it went all the way down & jammed with the engine still running, in my haste to get going i pulled the kickstart lever up & then there was a graunching sound, now even though the engine starts & runs fine i have a whirring sounds when revved like some things rubbing in the variator, so took the variator & starter clutch apart but could find no witness marks or signs of rubbing anywhere, took it to local bike shop & the guy with the stethoscope says noise is coming from variator area,  also ive had to increase tickover to keep it from stalling

could it be when i yanked the kick start up with the engine running that it lent on the crankshaft end pushing it in slightly & inducing crank walk & now the crank is rubbing on one side of the inner crankcase? 

[rupert]

I'd be more inclined to believe you have a bad crank bearing.

[andyfiggy]

ok, i know in most engines you have shims or thrust washers to take out some end float but what stops the crank moving laterally in a basic single cylinder 2 stroke engine? 
also is it possible to ruin your crank bearings or seals by using the kickstart to aggressively?

[rupert]

"what stops the crank moving laterally"

The bearings are a press fit in/on both the case(s) and crankshaft. To assemble an engine: you press the bearings on the crank, then heat each case half to install it. If there appears to have been some bearing movement in the cases I put red Locktite on the outside of the bearings before assembly. Once it is together (and cool) you whack the end of the crank with a dead blow hammer to settle the bearings in. There should be no lateral movement of the crankshaft in an engine assembled this way, if there is, look to a bad bearing(s).

"is it possible to ruin your crank bearings or seals by using the kickstart to aggressively"

Not that I know of. I would expect the weakest part to fail which usually is the aluminum torque converter (transmission) cover.

[shakerdriver]

I've seen the kick start gears move enough to cause rubbing on the kick start paw also. I would try putting a washer on each CVT cover bolt between the cover and case to see if that has any effect on the noise. If not keep trying other things but if you were that aggressive with kicking it that may be a quick solution.

Sent from my Nexus S 4G using proboards

[andyfiggy]

thanks, i reckon i loaded the bearing from the side which its not designed for, considering its a chinese 2T these bearings arent meant to last anyway so time to change to better quality ones