crankshaft problem

James Foster /

I just took a look at my crankshaft on my puch, and noticed that it has significant play in it. I know I should get a performance crank since it's got performance parts on it, but I don't have a lot of money. Does anyone know a way to fix this problem without breaking the bank?

Thanks,

JF

Re: crankshaft problem

Don Pflueger /

play where? side to side? up and down? connecting rod play? normally a crank wont get worn out unless there was a lack of lubrication. most likely a bad bearing.

Re: crankshaft problem

James Foster /
jf OP

There is play side to side where the rod connects to the crank. In other words, the main rod wiggles left and right a bit more than it should. Should I go for a costly new crankshaft, or is there an easier way to fix this?

Thanks,

JF

Re: crankshaft problem

if you have a 1 speed, i think my friend has a mint crank that needs a new rod, that he is replacing with a performance crank, so if you wana contact him, and you could just swap your rods you would be good, his e-mail is spyder_2000@hotmail.com

Re: crankshaft problem

Don Pflueger /

i would first look for a service manual and see what your wear limits are. side to side play in a connecting rod is not a bad thing unless the engine knocks when it runs. im that case, i would look into a performance crank.

Re: crankshaft problem

James Foster /
jf OP

Well that's my problem. When I'm driving it, it tends to have an irregular knocking sound that's not from bad timing. I believe the rod has too much play in it, but I dont have enough money for a nice new one. I might look into a used one, but is there any way to save my old crank, if nothing else until I can get enough money for another one.

Thanks again,

JF

Re: crankshaft problem

Don Pflueger /

best i can tell you is run it til it breaks

Re: crankshaft problem

James Foster /
jf OP

Well that works... I just hope it doesn't damage anything else if it breaks.:(

JF

Re: crankshaft problem

Don Pflueger /

thats the downfall. your damned if you do and damned if you dont. if you dont have the money for new parts, then your pretty much stuck with using the old stuff for awhile. but if the rod doesnt have any up and down play on the crank, and its only side to side, it should hurt anything unless you notice it catching on something, which could only be the lobes on the crank.

in other words. if the bushing/bearing on the lower end of the rod is not elongated. it will work fine. rods are always made wider where the bearing is to keep the shaft portion of the rod away from the spinning lobes on the crank.and in most cases, they do have quite a bit of side to side travel.

and unless the engine ran with no oil the lower rod bearings rarely ever fail. i would look closer to the upper rod bearing and wrist pin. maybe they are whats worn and making noise.

Re: crankshaft problem

James Foster /
jf OP

Ok, I just looked at the small end bearing but didn't notice much play at all. But that little bit could turn into a big problem later on, especially since I can't even go above 25. My top speed normally is a little over 30 mph, and now when I almost get there it makes an unsettling knocking sound and stops accelerating.:( It sounds like someone is knocking on the cylinder head with a screwdriver really fast. I have an old 2 HP crankshaft from a Puch Newport that isn't in the best condition, but could possibly use parts from it. Thanks again for the advice.:)

JF

Re: crankshaft problem

james

if you continue to run your moped with the crank with alot of play in it ......it will prematurely wear out your rings because of

all that side play. i had a vespa bravo that did the same thing.......had alot of play in the main bearings and i just kept on riding it.......eventually i replaced the main bearings but i also had to replace the rings....just so you know.

dont throw away your worn out cranks......someone in austria has to be making a rod kit for puch moped 1 speed cranks. if you can find a kit any motorcycle dealer can

rebuild your crank........i know im looking for a rodit

leo

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