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Noticed a difference in the piston's I took out of my bike and the pistons that I bought from Kawasaki when I got them home, are they interchangable and what's the purpose of having two different types?

Old Pistons (marked 707 with a flat top):



New Pistons (marked 657 with a ridged top):



Comparison:

No idea, but thats pretty damn interesting that they are different!!

did you order the correct year piston?

Yup, ordered them for the L3 which is the year of my chassis but not sure if the motor is from a different model zxr400?

Wouldnt count that out.. May have been better to supply an engine number.

RedexRobB wrote:Wouldnt count that out.. May have been better to supply an engine number.

Agreed, will chat to the suppliers tomorrow and see what they say.

So then! I found both pistons are for an L3 but one is for a UK L3 and the other is for a Japanese L3, two different part no's. I didn't have time to check but my friend at the dealershop is going to check that the UK and Japanese L3's: Cylinders, Cylinder Head, Cams, Valves, Conrods, Crank etc are the same by comparing part no's and if so they're interchangable and I'll use them.

looks like the UK spec ones would give a higher compression ratio ..

Perhaps the 707's which came out the bike are designed for slightly lower comp for lower power to be line with Jap restrictions of bikes at the time?

maybe ... they look the same as the ones in my H engines ... I'll check the part numbers later.

spot on, thanks.

Unless I'm absolutely certain that there is no difference between the Jap and UK L3 motors (other than pistons) I think I'll most likley stick to the ones that came out of the bike, any difference in power between the two is probably so marginal I'd probably hardly notice it on the road.

If you don't use them. how much do you want for them..cheers.

Regrds TK400

Not for sale, exchanged the 657s for 707s free of charge.

sorry for the delay

checked my box of pistons ..

all are marked 657.. all came out of H model engines

I have heard about some import L's circa L3/L4 that had lower compression and milder cam profiles.. looks like yours is one

tbh, if you can.. i'd swap them back and fit the 657's to gain a touch of compression.

might be worth checking out any differences with your cam's aswell.

I'll see if I can get the 657s back, they've got to be interchangable with the 707s eh?

I need to strip the motor out of my UK L1, might use the cams out of that for my L3....