A buddy and I have decided to build a GS track bike and I must absolutly suck at seaching because I cant find what pistons are currently available and where I can get them.  My buddy owns a machine shop and weve got an extra engine sitting there but we are trying to figure out where to get the pistons and what size.

Thanks all

also will porting and polishing the heads give me anything as far as power goes?  Class rules allow me to go to 560cc's with out getting out of the superlight class.

Brad

555cc

Dgyver Has a post round here somewhere , search 555cc or sum it i think

I thought you couldnt get the 555 pistons anymore?

ok figured it out, 541 is the biggest you can go currently. 

Will Porting and polishing give me anything worth while?  Im thinking of milling the head as well good idea? 

Cams?  dont want to do anything radical here but maybe a bit more there.

Should I do anything to the crank?

Cool thanks

Brad

541cc can be done with GPZ1100 18mm wrist pin pistons

Porting and polishing will never hurt, but the gain may not be worth the time investment. I have never done it so I am not sure how much gain is available.

If you do the GPZ1100 pistons I would recommend that you check what kind of compression you will be getting. The GPZ1100 pistons have a higher crown, so you will be bumping up the compression and then if you mill the head the compression increases again.

Cranks, so I have heard, are the weak point of the engine once you start increasing the HP. Maybe have it cryo-treated and see if that helps

Thats what i was thinking, Cryoing the Crank, there is a local facility here that does it

Im thinking of Boring the cylinders, then cryoing the crank and seeing what kind of gains i get with HP and compression and then deciding weather or not to mill the head.  but Considering i have the facility to do all the work i hink ill port and polish just to see. 

Ill probably need some help with the jetting once done, or at least a good starting point.

Can someone please Link me to somewhere to buy the pistons wrist pins and such?

Cool thanks

Brad

Quote from: darb85 on October 16, 2007, 01:00:32 PM
Can someone please Link me to somewhere to buy the pistons wrist pins and such?

Cool thanks

Brad

http://gstwins.com/gsboard/index.php?topic=14401.0

The more I learn about porting and polishing, the more I feel like it's a crock.

I think if I ever have a spare GS engine open, I'd try the motoman velocity porting technique.  http://www.mototuneusa.com/homework.htm

the Srinath has a 651cc GS.....

Quote from: Chuck on October 16, 2007, 05:46:28 PM
The more I learn about porting and polishing, the more I feel like it's a crock.

I think if I ever have a spare GS engine open, I'd try the motoman velocity porting technique.  http://www.mototuneusa.com/homework.htm

Is this serious.  I'd like to see some outside dyno gains and see if any of that is true or if it is a bunch of crap!

that doesnt make any sense what so ever.... unless im missing something but it doesnt make any sense to me..  this guy goes against known engine building

Just an FYI those pistons are now 126 a piece.

speed is just a question on money... how fast do you want to go.
so a piston kit is 250-300
cams are about 300
CR specials are about 700
bore job is 30-50 a hole
time...lots
unless you are racing a gs in a class for personal reasons....buy a faster bike to go fast
less effort and easier on the brain and pocket

What's the 'CR Specials' mod?

CR carbs, there are some for sale in the Buy/Sell section for $200 bucks

"Biggest bore you can go to right now?"

I thought this thread was going to be about ... I don't know ... Al Gore or Oprah or folks like that. 

Quote from: werase643 on October 17, 2007, 05:23:27 AM
speed is just a question on money... how fast do you want to go.
so a piston kit is 250-300
cams are about 300
CR specials are about 700
bore job is 30-50 a hole
time...lots
unless you are racing a gs in a class for personal reasons....buy a faster bike to go fast
less effort and easier on the brain and pocket

Ive got a GS sitting around that needs a Engine Rebuild, well rather a buddy did so I bought it.  for 200 bucks...

Ive got a machine shop in town owned by a family friend willing to do all my work for me at extremly low costs.  so It wiould be a lot cheaper to do this.  I have to use stock like Carbs but other than that Engine is work will be very cheap for me. 

So I look at it as being a cheap fun way to get started.

Quote from: Kerry on October 17, 2007, 10:00:53 AM
"Biggest bore you can go to right now?"

I thought this thread was going to be about ... I don't know ... Al Gore or Oprah or folks like that. 

Ahh Kerry how I have missed your posts...good to see you back

Ok heres a cost write up for me

126 per Piston= 252
wrist pins=20
Clips yada yada=40
40 bucks per Jug for boring=80
Port and Polish= 75
New jets and other stuff=50(ya might be low or high...)
Cryo the Crank=150

Total=667.  Pretty cheap if you ask me for the performance gain.



So running total as of now is

Bike               200
Engine work  667

Total              887

Expences not yet realized

Woodcraft rear sets 150-buddy had another set sitting around
Race tires                 
Sprockets                   Very short straights, dont need super top end
No Oring Chain         120

So all in all this will be a very cheap race bike.

Brad