November 13th, 2020, 08:33 AM | #1 |
ninjette.org member
Name: Frederic
Location: Quebec City
Join Date: Jan 2020 Motorcycle(s): 08 Race Prepped ZX-10r, 09 Race Prepped Ninja 250 (300 motor). 74 Norton Commando 850 (Project) Posts: 55
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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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November 13th, 2020, 09:48 AM | #2 |
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Name: Chris
Location: Bristol, UK
Join Date: Feb 2016 Motorcycle(s): ZZR250, VFR800 Posts: 478
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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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November 13th, 2020, 12:25 PM | #3 |
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MOTY - 2018, MOTM - Nov '17
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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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November 13th, 2020, 12:34 PM | #4 |
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Name: Eric
Location: Iowa City
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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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Top speed 123.369mph. Ohio mile Worlds fastest 250 ninja |
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November 13th, 2020, 01:23 PM | #5 |
ninjette.org member
Name: Frederic
Location: Quebec City
Join Date: Jan 2020 Motorcycle(s): 08 Race Prepped ZX-10r, 09 Race Prepped Ninja 250 (300 motor). 74 Norton Commando 850 (Project) Posts: 55
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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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November 14th, 2020, 08:29 PM | #6 |
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Name: Eric
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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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Top speed 123.369mph. Ohio mile Worlds fastest 250 ninja |
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November 15th, 2020, 06:30 AM | #7 | |
ninjette.org member
Name: Frederic
Location: Quebec City
Join Date: Jan 2020 Motorcycle(s): 08 Race Prepped ZX-10r, 09 Race Prepped Ninja 250 (300 motor). 74 Norton Commando 850 (Project) Posts: 55
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Quote:
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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November 15th, 2020, 08:17 AM | #8 |
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Name: Eric
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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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Top speed 123.369mph. Ohio mile Worlds fastest 250 ninja |
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