brake piston do I need to replace?

I just pulled out my brake piston for my 1981 xj650 and it has two very small indentations. do I need to replace it and do I need to replace the seals or can I reuse them, also if I need to replace how much do the pistons usually go for. Thanks

 

IF the brake was leaking fluid then those indentations were the reason. If it wasn't then all is well. Pistons are $29 at partsnmore.com and the rebuild kits are $14. However the kit they have pictured is for two calipers. If yours only has one then buying the seals from the dealer would be better. I believe I needed one seal per caliper and it was $8 each.

 

Vise grip signatures from an abused past. ALWAYS reseal those things, the seals only live a year or 2 at best.. and Don't be Lazy ..reseal.. Both calipers. at the same time regardless of your opinions about it.
Stopping Fred Flintstone Style, while entertaining for spectators, is kinda risky.

 

let me clarify its on the lip so when i flip it over it you can see light maybe a mm at most, and I have a xj650g the partsnmore website was for a xj650R, and does anyone know what year sidecovers my bike will take I messed mine up in a freak sanding accident.

 

If it is on the part of the lip that contacts the brake pad then it is no problem. I was probably made by the PO leaving the anti rattle shim out and the allowing the pad to mar the piston. If it is on the side and far enough down to engage the rubber seal then I would replace it. Either way it is your main brake. If you don't have confidence in it then I would replace it for my own peace of mind.
Someone else will have to answer the side cover question. They all look the same to me but the part #'s are different. This could be style alone or a change in fit.

 

All the 650 Maxim side covers will fit.

You're in luck. I have a set. I should get into the shed this weekend. I'll dig them out and shoot you a pic. (You might send me a PM to remind me).

**EDIT**
Just remembered I have a pic. Check your PM.

 

I did some checking on the piston and need the diameter and length to match it. The partsnmore piston fits the 4K0 caliper but that was only used on the European G model. Yours uses the 4H7 caliper. If you have a good metric measuring caliper the piston can be matched to some listed on oldbikebarn.com

 

If the marring is within the shadow of "Always exposed" Piston end ... don't worry about it.

You should replace the Seals, though. Easy enough to do.
But, before you just replace the Seals ... make a Tool and scrape-out the channels where the Seals seat.

Right down to 100% Cleaned-off of everything, perfectly clean, Aluminum Caliper.
That will make putting the Piston back-in a little bit easier.
Lube with fresh brake fluid when you start the re-assembly!

 

Okay I am going to keep the piston after cleaning it up, and replace the seals. Thanks for all the help