backfiring!!!!!!!

[stred-aerox]

dont know if it is correct, but on sip-scootershop when they show you how to fit a crankshaft they also tap it after wards to relieve tension! But that was on min. horiz. so it may be different for the piaggio engine.

Im doing my crank next week for the first time so does anybody have any other tips? Cheers.

 

[Browni]

dont know if it is correct, but on sip-scootershop when they show you how to fit a crankshaft they also tap it after wards to relieve tension! But that was on min. horiz. so it may be different for the piaggio engine.

Im doing my crank next week for the first time so does anybody have any other tips? Cheers.

Sure there are lot of methods, kick, tap, hit, but there is only one that don't damage the bearings

 

[stred-aerox]

o.k i allready have a pulling tool.. how do i pull it?

 

[roost]

Browni,
Well, yours is one way, I do it annother way.
But you can't say it can't be hit. Not if you do it like I do it.
At 80-90°C of block temperature the outer bearing rings become nearly loose. So it's easy to set the axial play.

Oh, please, how can that damage the bearings


Bearings can't be damaged that easily. Bearings get damaged because of improper mounting, in a running engine over some time.

 

[stred-aerox]

sorry to go off topic. But do you heat after you have done up the casing bolts? I have a high power heat gun thingy..

 

[roost]

I do heat it up. Slowly and evenly ofcourse.

 

[Eoin70]

just place a spacer in between the crankshaft weights

it'll prevent any damage to the big end bearing
i usually wedge the open side of a large spanner into the crank through the intake opening in the engine

it prevents any damage to the crank or the bearings

and yOU CAN THEN hit it into place

 

[Browni]

Browni,
Well, yours is one way, I do it annother way.
But you can't say it can't be hit. Not if you do it like I do it.
At 80-90°C of block temperature the outer bearing rings become nearly loose. So it's easy to set the axial play.

Oh, please, how can that damage the bearings


Bearings can't be damaged that easily. Bearings get damaged because of improper mounting, in a running engine over some time.

Yes you said the truth Hitting is an improper mounting!!

80-90 °C is not too much 100-120°C is better

Sure I know the alu. has 2 times bigger heat expansion coefficient than the steel (I don't know the right english designation of this word.)

And if you don't see the dameges with your eyes it doesn't mean they are in excellent condition, there are microscopic damages at the surface, so the life of these bearing are half (or more) of the real! You can check it with oscillation test or other diagnostic method

 

[roost]

100-120°C (as Piaggio says) is not necessary. I do 80°C Minarelli, 90°C Piaggio.

Oh, come on! The force is far under where deformations would occur to the high hardness of the balls and rings surfaces. And you know that.

 

[Browni]

100-120°C (as Piaggio says) is not necessary. I do 80°C Minarelli, 90°C Piaggio.

Oh, come on! The force is far under where deformations would occur to the high hardness of the balls and rings surfaces. And you know that.

Not only Piaggio says, but the SKF user manual too Maybe it isn't necessary at the 50 cc Piaggio engine, but I repaired some 125 and 180 cc Piaggio engine, and the bearings was very tight in their place at 80-90 °C.