SRX 440 crank and case questions

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yamaton

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What is the difference between the 1977 SRX crank and the 1979 SRX crank, besides the rods that takes the larger wrist pin? Is the counter weights the same and so forth?

Is there any differences between the two crank cases, besides the larger cylinder bolts on the 79 case?


The reason I'm asking this is that I'm thinking about putting a 1977 SRX top end on a 1979 bottom end, using the 77 ignition, CDI-unit and flywheel.


My first post here!

Thanks // yamaton
 
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DUDE, YOU CAN DO THAT WITH NO PROBLEM. WE BUILT A SRX MOTOR AFEW YEARS BACK BASISLY DOING WHAT YOU WANT TO DO. WE USED A 78 SRX BOTTOM END AND CASE. 78 SRX ING, 8F2 CYLINDERS, 8H0 SSR HEADS. NOW THOSE CLYINDER STUDS WERE STILL THE SMALL SIZE UNTIL MID YEAR IN 78 WHEN YAMAHA WENT TOO LARGER BOLTS. ONLY PROBLEM I SEE FOR YA IS 77 ING ON 79 CASE. 3:16 (tony)
 
You can use all the 79 ing. stuff take the flywheel weight off the 79 use a 8k4 cdi box for more 10,000+ rpm if you dont have a 77 cdi.
 
Thanks for the reply's, 3:16 and yamaha one, sounds great! I'm planning to run a 77 ignition, stock 77 carbs and AAEN stingers in this one to start with. What is the origin of the 8k4 cdi-unit? I might have one of those laying around as well. Good tip anyway!

3:16, long time no see! Still got that nice `80 SRX?
 
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Cdi box question? 76 & 77 had no rev limiter. Correct? 78,79and 80 did? What's 8K4 cdi? I have some with a ton of other numbers on them. Anyone know what's what? Any list out there? Come on Tony. You must know some of them.Thanks Dean-o
 
I looked though my srx stuff and the extra CDI box I had was an 8K2 unit, `80 srx I guess.
 
to run the '77 top end on a 78 bottom end you will have to drill the cylinder bolt/stud holes in the cylinders to accept the larger 78 dia cylinder studs. the 76 and 77 used a smaller dia cylinder stud.
 
8K4 IS A 1980 SRX CDI, THEY HAD REV LIMITER. 78 AND 79 SRX CDI SHOULD HAVE 8G9 PART NUMBER ON THEM AND WILL GO TO 10,000 !! 3:16 (tony)
 
TYPED BEFORE I THOUGHT !!! 8K4 I BELIEVE IS EXCITER. 8K2 OF CORSE IS 1980 SRX. YAMATON, DUDE YEP I STILL HAVE MY 1980 SRX AND A 1979 SRX !! LOVE THEM, NEVER SELL THEM !! 3:16 (tony)
 
my mod 81 and 77 both run 8k4 both turn 10,200 both sleds have turned 11,500 in testing with the 8k4 cdi.
 
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