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Will flat top pistons work in GS450?

  • Thread starter Thread starter safwan.khan
  • Start date Start date
S

safwan.khan

Guest
Hi all,
I live outside US and do not have access to spare parts easily. I am rebuilding a GS that I bought a few months back and it has a cracked piston. After looking around for alternate and measuring sizes, I have come to know that Lancer (1985-1986) pistons are similar in dimensions to the original dome head GS pistons however they have a flat top.

Now my question is, if I replace pistons on my bike with identical flat top pistons, how will it affect the performance and fuel economy? I have read about it a bit on the forums and figured out that flat top pistons will reduce the compression ratio in the cylinders a little bit but I am no racer so can compromise a little bit here, but not too much. :-k
 
salty_monk said:
Suspect he means Mitsubishi Lancer...
Click to expand...

I seem to remember there's something even worse called a lancer in India...

The answer you're looking for is that if it'll get your 450 running again, do it.
The drop in compression will lose performance, yes, but there's not a lot there anyway - and you'll be able to use low octane petrol too.
 
Thanks for the helpful advice friends. I managed to get my hands on a slightly used gs450 piston from a local junkyard mechanic which seems to make an OK combination with the working one that I already have. So it looks like I am good to go with the stock pistons for now :)

P.S., I love this website!!
 
as far as piston diameter and the pin have same size....then it will be fine....

i live in indonesia and and many of bike using car piston to bore up displacement....including me...
i'm have gs250 with KIA s515 piston inside...and made new custom liner (bore)....its more safely to have thicker bore if u gonna do boreup diaplacement

but if i have much money....then i'll go to wiseco...and order custom forging piston online....it can make my bike accelerate much faster
 
Last edited:
Can you please tell me a bit in more detail about it with links to the piston that you are referring to? It seems interesting and I might end up trying it out :)

GregT said:
I seem to remember there's something even worse called a lancer in India...

The answer you're looking for is that if it'll get your 450 running again, do it.
The drop in compression will lose performance, yes, but there's not a lot there anyway - and you'll be able to use low octane petrol too.
Click to expand...

celesboy1 said:
as far as piston diameter and the pin have same size....then it will be fine....

i live in indonesia and and many of bike using car piston to bore up displacement....including me...
i'm have gs250 with KIA s515 piston inside...and made new custom liner (bore)....its more safely to have thicker bore if u gonna do boreup diaplacement

but if i have much money....then i'll go to wiseco...and order custom forging piston online....it can make my bike accelerate much faster
Click to expand...
 
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