Would new crank make bike run different?

[Ride_blue82]

I just rebuilt my whole motor and instead of using an oem crank I used Wiesco, ever since this my bike has started idoling way higher than it use to and seems to have no over rev now it just will rev real high in the air instead of over reving, this is for a 2002 yz 125 thanks for help in Advance

[woods guy]

Could be an air leak from reassembly

[05CRF250]

High idle is most likely an air leak as mentioned. As for the over rev I would check the ignition timing is set correctly.

[Ride_blue82]

It did not do this at first but after a hard moto it randomly started doin it and has did it ever since then

[Excitable]

try the starter fluid check on her.

[Ride_blue82]

How do you do that?

[yz250474]

How do you do that?

Spray around the intake boot/reeds while its running, see if the idle raises. if it does its an air leak. could also be a crank seal.

I need to build me a crank case pressure tester, I think its only $20 to make 1.

[Ride_blue82]

We sealed a bunch of the things you just named with silicone

[Excitable]

We sealed a bunch of the things you just named with silicone

?

 

should not need silicone to seal those things up.

[yz250474]

We sealed a bunch of the things you just named with silicone

You put silicon on the crank seals?... spray anyway with it running see what happens.

[Ride_blue82]

Did not put it on crank seals did put it on around reeds, powervalve and a couple other places

[numroe]

Silicone is temp fix. Messy later too. Best to find the leak first. Crank seals is a good bet.

A problem with the crank can wear new seals. Or the seals could be faulty or maybe damaged during installation.

Edited November 14, 2014 by numroe

[Ride_blue82]

What would it mean if black oil was leaks occasionally from black tube at the bottom of the motor

[Ride_blue82]

Coming from powervalve it looks like

[IacobucciB]

I had a cr80 that did the same, crank seals were shot. Of course the bike was a beater and I didn't care. I submarined that bike 4 times and it would start 2nd kick every time, till it blew a fist size hole in the crankcase after a little too long pinned on an old fire road

[05CRF250]

Is it coming from the powervalve or transmission vent tube ? If it's from the powervalve it's nothing out of the ordinary.

[Ride_blue82]

Coming from powervalve tube