I searched and found this thread https://honda-tech.com/zerothread?id=191739

I want to know how one goes about doing so? The above thread wasnt very informative except for what to use.

TIA

 

what I have done is use 120 cartrige rolls from standard abrasives and just hit the sharp edges around the valve relefs don't go crazy with it though and use masking tape to tape around the top of the piston so you don't mark up the sides just leave the top of the piston exposed. good luck!

 

wrong thread


[Modified by eddiecut, 4:13 AM 1/29/2003]

 

sand the sharp edges to prevent any potential temperature risers. Higher heat buildup results in a greater risk of detonation.

 

to de-burr piston tops, i usually use a worn out sand roll with a die grinder. this will create less deep sanding marks. after removing all the sharp edges, i use a cross buff with a die grinder as well with wd-40 to polish it up to get and even finish on the piston tops. oh, it would help if you had a piston vise to hold the piston in place





[Modified by vhd, 9:15 PM 1/28/2003]

 

after sanding it wouldnt you need to balance them since your takin off weight by sanding it and being that your eyeball isnt the most acurate tool.....?

 

your not going to take off enough material that you would need to rebalance the whole rotating assembly where just talking about taking the sharp edges off the valve reliefs right? oh I did forget to mention the die grinder an important tool you need to use the cartrige rolls I mentioned before thank you vhd for reminding me!

 

Rebalancing is a good idea...you just need to do the pistons with the wrist pins - not the whole rotating assembly. Make sure you keep the wrist pin with the particular piston after they are balanced.

Kirk

 

Like the original post said you should sand the bottoms of the skirts also. Use only "super"-fine sandpaper. Like 1000+ grit. Be careful and go slowly.

 

you shouldn't take off enough material that you have to balance the pistons you wouldn't even see it on the scale. your balancing the rotating assembly when you balance a crank so if you take enough material off the piston to change the balance of the piston you have to balance the hole assemby.


[Modified by HEAD, 11:34 AM 1/29/2003]

 

couldn't u just use scotch brite?

 

I think how much you are taking off is entirely dependant on how deep the valve pockets are and how much you are trying to unshroud the valve - I have seen enough material removed that it has made the pistons unequal in weight and did need rebalancing...

I respectfullydisagree...as long as you have not changed the counterweights on the crank it does not need to be rebalanced. What you are suggesting here is that if I change the weight (as they have now been rebalanced) of the pistons that I need to balance the rods, crankshaft, flywheel, pressure plate and crank pulley again - why? what have you effected in any of those pieces that made them out of balance?

Kirk

 

I could be wrong but I think the original question was SANDING the rough edges off the top of a piston, which would not be deshrouding or reshaping the valve reliefs, I don't know about using scotch brite I think it would take to long I've never used it for this.

I respectfullydisagree...as long as you have not changed the counterweights on the crank it does not need to be rebalanced. What you are suggesting here is that if I change the weight (as they have now been rebalanced) of the pistons that I need to balance the rods, crankshaft, flywheel, pressure plate and crank pulley again
now if we DID decide to change the shape or size of the relief or dome we most certainly would need to rebalance the pistons and get them as close to weighing the same as we can, hopefully within a half a gram, now this would change the counter weight that is on the crank because the counter weight is the weight of the rod,PISTON, rings which are the things that rotate on the rod journals during operation, so yes we would need to balance the rotating assembly but not everthing seperate again. Is the honda internally balanced or externally?

 

thanks everyone, very informative! any addt'l info please post!

 

Honda does not bolt everything together and spin balance them...they are done as individual pieces external of the block.

If you lighten the rods/pistons and leave the counterweights on the crank the same, the crank will be better equipped to spin up tighter - in my race motors, we run as light a rod/piston combination as is we can and we add weight to the crankshaft counterweights and then rebalnce the crank by itself. We see tremendously better life out of the main/rod bearings when we do. Is this the type of rebalancing you are talking about? I assumed (sorry) that you were only talking about just sending the crank to a balance shop (after changing rod/piston weights) and having the shop check the crank again, but you haven't done anything to change the cranks natural balance...

Kirk