can i use this piston

S

SPARKY10

New Member
#1
#1
This came out of a siezed (siezed from being out in the rain not racing)engine that i freed up with patience and P.B. Blaster it is a wiseco 186 chrome piston. Can I use it or is it garbage take a look at the scoring. Sorry about the picture quality but metal is hard to photograph
 
Neck

Neck

Growing up is optional
#6
#6
To be sure, you'll have to measure the cylinder and the bottom of the piston skirt.
you don't want the clearance between the two to exceed say .004 thousandths.
We race with more scoring than what I can see in the pic. As long as the rings are free in the ring lands, and the ring lands are clean, and it's not too sloppy in the cylinder run it!
What kind of racing are you planning on doing?
 
S

SPARKY10

New Member
#7
#7
i am building the engine mostly for fun not racing. My concern was the it looks like the chrome is worn off in a few places and somewhere i read that an alumninum piston in an alumnim bore would sieze. the scratches look like some one ranover the sides with 80 grit. but they are only on two sides parrallel with the rod the rest of the piston is fine. is there anything i shoud do to minimize the scratches?
 
Neck

Neck

Growing up is optional
#8
#8
I can't really see to good, but as long as the piston material isnt bulging out of the scratches, no. Is the surface generally smooth. Clearance is generally the key in piston seazure, that and piston speed, which you dont have to worry about because your not revving it that high, and of course, lubrication. The chrome is for long life. was the engine you took it out of an alumineum bore?
 
Neck

Neck

Growing up is optional
#10
#10
I bet the rings got messed up from the rust! if it measures ok replace the rings and run it! What do you have to lose?
 
S

SPARKY10

New Member
#13
#13
Hey Briggs, thanks for chiming in. From reading your other posts i value your opinion. The numbers on the top say 1986 and it is a standard bore, take a look at the attachment. Let me know waht you think. BTW the engine had the 4.75 inch rod also on the attacmnet so i know it's a .590 compression height setup

http://www.apskarting.com/pdfs/100-107.pdf
 
Last edited:
Neck

Neck

Growing up is optional
#14
#14
Do you have a digital caliper you can measure the pistons with? take your measurment and then compare. If their very close in size, like within .002 thousandths and you use new rings
there should be no damage to the nice bore.
 
alfalfa

alfalfa

Member
#16
#16
If you can feel the score with your fingernail, its too much. If its lightly scored, i would just polish it up with some sand paper. also, unchromed and chromed become confused quite often, i have many "chromed" pistons, they are just coated so the engine doesn't seize (just like you said), they are not necessarily always shiny, although they can be, I would go on 4cycle and ask the guys there if its chromed or not with part numbers and such, also if you see any of the chrome flaking off then its a chromed piston, (obviously) but then you cannot use it, it will eventually all flaake off and lose the coating causing your engine to seize , aluminum to aluminum
 
65ShelbyClone

65ShelbyClone

Well-Known Member
#20
#20
If you sand the scratches out, then you've removed most of the chrome and the piston will be unusable in an aluminum cylinder anyway.

I can tell from the pictures that that piston is really questionable. This is what a good stock CoolBore slug looks like:

 
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