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Discussion Starter · #1 ·
Hello,

I bought a motor to replace my blown '86 motor. The seller told me it was a '92, but when I took the cam cover off it had the forked rockers so it must be a '90 or earlier motor. Is there some way to tell the year of the motor?

Thanks,
Yancy
 

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what's the exact displacement stamped on the left side of the cylinder block?

the long stroke motors (86, 87, 90) were 749cc's, the short strokers (88-89) were 748.

[ 10-19-2001: Message edited by: jeff ]</p>
 

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also check the color of the paint on the motor - if it's a charcoal color, it's a gsxr motor, if it's a gloss black color, it's a katana motor....
 

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Discussion Starter · #4 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by jeff:
what's the exact displacement stamped on the left side of the cylinder block?

the long stroke motors (86, 87, 90) were 749cc's, the short strokers (88-89) were 748.

[ 10-19-2001: Message edited by: jeff ]
<hr></blockquote>

Hello,

Thanks for the reply. It's a 749cc, but I'm not sure of the year. I thought the '90 motor's redline is at 13K while the `86/7 is at 11K, so I'd like to make sure of the year before I try to rev it higher than 11K.

Thanks,
Yancy
 

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yeah, the 90 revs to 13k......a quick way to tell would be to measure the diameter of the intake ports (after removing the intake manifold boot).....the '86 should be around 31mm, the '87 34mm, the 49 state '90 38mm, california '90 36mm, to match their respective carb sizes.

assuming of course that no head swapping has been done.



you can also try pulling the signal generator cover and look at the ignition rotor - the 86 and 87 have a rotor that only has one large 'trigger', whereas the 90 has one large trigger and 3 smaller ones, all of which are spaced evenly about 90 degrees apart from each other.

again assuming that these are stock (or simple advanced) rotors.....aftermarket ignitions may use their own rotors....
 

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Discussion Starter · #6 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by jeff:
yeah, the 90 revs to 13k......a quick way to tell would be to measure the diameter of the intake ports (after removing the intake manifold boot).....the '86 should be around 31mm, the '87 34mm, the 49 state '90 38mm, california '90 36mm, to match their respective carb sizes.

assuming of course that no head swapping has been done.



you can also try pulling the signal generator cover and look at the ignition rotor - the 86 and 87 have a rotor that only has one large 'trigger', whereas the 90 has one large trigger and 3 smaller ones, all of which are spaced evenly about 90 degrees apart from each other.

again assuming that these are stock (or simple advanced) rotors.....aftermarket ignitions may use their own rotors....
<hr></blockquote>

Thanks Jeff; I'll take a look at the intake ports and the ignition trigger and see which year it is.

Yancy
 
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