mikstr

Anyone know the weight of a stock piston? I thought someone had listed it on here previously but my searches (yes, I serached before posting) came up empty. I ask as my new JE`s are listed at 390 g (0.5 mm OS, with skirt and top coating) and I wondered how they compared.

cheers

killer5280

I didn't weigh them, but I noticed when I did my piston swap that the stockers are quite a bit lighter.

RCVTR

Here's what I got when I weighed mine (stock vs. std. bore JE's):

Stock piston: 402.5 g
JE piston: 388.4 g

Stock wrist pin: 130.4 g
JE wrist pin: 117.6 g

mikstr

Thanks

so the weight difference is rather small, I was expecting more than that to be honest. At least it`s in the right direction (lighter).

P.S. just to be clear, you are referring to the VTR and not the RC right?

killer5280

I'm surprised. I'll have to weigh the stockers to see what mine weigh, but I swear in a side by side very unscientific comparison the stockers seemed lighter.

mikstr

maybe the lower density of the cast pistons makes them seem that way, lol

RCVTR

Yes. Those were Super Hawk pistons

mikstr

great, thanks again!

Firestorm996

If you dont mind the money, throw in a set of Ti wrist pins and save even more weight.

mikstr

If I knew where to find some I might give it some thought....

Firestorm996

http://www.angelfire.com/biz5/traunerotiwristpins/

Firestorm996

this link give you a idea about the weight......
http://www.tipro-fasteners.com/Mp.html

mikstr

Thanks Peter. I just did a quick search and found info showing that, while lighter, they are not as durable so I'll pass as I plan to ride the bike for many years to come, and don't want to be opening it up to replace a wrist pin every year.

RCVTR

The way to lose weight from the rotating/reciprocating mass is with rods.

Stock VTR rods weigh 560g - 1120g total
Carillo RC51 rods weigh 480 g - 960g total.

A similar amount will be removed from the crank, after balancing.

I'm almost certain Carillo will still manufacture VTR rods. Dynoman Performance (dotcom) sells them for less than Carillo will sell them to the public.

gboezio

Are you taking some weight off the counterweight or leaving it a tad overbalanced ??
It should be ok still,I guess it depends if you pull out the crank, it's definitely not the same job.

mikstr

Crank will definitely be coming out as the cylinders will need to be bored 0.5 mm

RCVTR

You can get away with not balancing with a piston swap. It is a small change to the reciprocating mass.

Rods would definitely require lightening the counterweights. They make a big change to the rotating and reciprocating mass.

VTaRse

Are RC 51 SP1/2 pistons worth exploring?
They're 2mm diameter larger, don't know if the bores will take that without distorting.

And are they higher comp that Superhawk standards?

mikstr

Different piston pin diameter. There is also the matter of the deck height....