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Old November 13th, 2020, 08:33 AM   #1
Fred659
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345cc Cam Degree Suggestion

Hi,

I would like to know if you guys have some suggestions on what would be a good stating point for cam degree on a 345cc engine.

I plan to use 2 intake cams and it is also a race / track bike.

Thanks

Last futzed with by Fred659; November 13th, 2020 at 10:59 AM.
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Old November 13th, 2020, 09:48 AM   #2
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Tell us about this 345cc build !? I guess the stock timing is best for max torque through the rev range. Ideally more duration/lift cams for the best topend.
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Old November 13th, 2020, 12:25 PM   #3
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Once exhaust is done, then you design cam to tie it all together. Book mentioned here is highly recommended.
http://www.mezporting.com/exhaust_length.html

I recommend Elgin Gams (original Dima, there's some copy-cats out there). I prefer him over Megacycle or Web Cams Inc (not recommended). I've gotten cams from Web Cams with 4 different lobes all rotated to wrong angles.


If you're using factory intake-cams, use factory exhaust timing and retard intake 1-1.5 degrees and go from there.
https://www.spearsenterprises.com/pr...300-2008-2017/
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Old November 13th, 2020, 12:34 PM   #4
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Spread the lobes just a tiny, tiny bit and test. Use a compression tester to start testing. Mark the cam location. Make a tiny adjustment then rotate the engine carefully to check for interference. Then retest compression.
Depending on timing, fuel and piston compression ratio it does not take much to start having detonation.
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Old November 13th, 2020, 01:23 PM   #5
Fred659
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I will have:

ex300 crank (no balancer shaft, crank rebalanced)
ex300 head (ported)
2x intake cam
13 zx-636 pistons and rods (rods need to be slimed)
05-06 exhaust (8) valve springs (2 shims as garth285 thread - 49078-1216)

If someone as a link for a balacer shaft eliminator part. please let me know. I can do it myself but would prefer to buy instead.
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Old November 14th, 2020, 08:29 PM   #6
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Can you machine away the gear and leave the shaft in place?

What is the advantage of removing the balance shaft?
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Old November 15th, 2020, 06:30 AM   #7
Fred659
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Quote:
Originally Posted by Racer x View Post
Can you machine away the gear and leave the shaft in place?

What is the advantage of removing the balance shaft?
Yes I could machine it but will do an alu piece if anything. you need something there to channel the oil to the rest of the motor. you cannot just remove it.

Also, I will use rods and pistons that throw the stock balance off and I need to rebalance the crank anyway. (zx6 rods and 67mm pistons) If the crank, pistons and rods are balanced (high rev bias) I can save some rotating mass by not using the balencer.

Last futzed with by Fred659; November 15th, 2020 at 11:07 AM.
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Old November 15th, 2020, 08:17 AM   #8
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The best way is to make a plug that’s for sure. Definitely need to rebalance for different rods and pistons. JE pistons work without balance but if you are going to go wild it’s best to rebalance.

I use Corollo rods. They are close but still need to balance
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