visual difference between GS 550 and gs 650 heads

[boris.h]

Hi everyone. I did not find any serial number on the head I received.

I never had a gs 550 disassembled head on my hands. Could you tell me about how to recognize them? thanks

[tkent02]

Show me a picture and I'll tell you which head it is.

[boris.h]

[tkent02]

How about a pic of the cooling fins on the end off the head? I don't have my heads here to look at.
The 650 head is more squared off, more fun area, the 550 head is smaller and more rounded.

[Steve]

If I remember correctly, they use different size spark plugs.

.

[Guest]

You do remember correctly Steve. I don't recall the exact sizes, but the 550 takes the 'standard' plug, whereas the 650 takes the smaller one.

Also:


If you look at no.4 inlet, you will a small bolt head to the right, level with the top of the inlet. This is absent on the 550.

[boris.h]

ok, thanks guys!
My new head uses 12 x 125 threads for spark plugs whereas the 550 uses 14x125 ones. So I think I have a 650 head