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 HPC crank ?'s 
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scooters and mods: 2003 Kymco Bet&Win 250; MRP 300cc kit FAST!!! *NEW* 2001 Yamaha ZUMA, mods to come!!!!
Post HPC crank ?'s
I'm wondering if a full circle crank noticeably decrease lower end torque? Most of the sites say the power band gets moved up, and a slight loss of acceleration. I'm building a torque monster, with a max rpm of maybe 11000 pegged downhill. Will i even benefit gettin a HPC crank (with 70cc of course)? I don't want to go with a full circle and loose that off the line punch. I've decided to go with the polini corsa 70cc which should be happy around 10,000 with my LV zx, i don't want to end up moving the powerband much higher than that. I plan on getting either a reinforced or hpc and new seals /bearings and porting the case either way so if its worthwhile i would throw down extra cash on the hpc.

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2001 "Yamaha" Zuma PreBug. MXS Race .55 squish, Polini Evo crank and evo bearings, Malossi Overrange 5.5g rollers, Stage 6 MKII Clutch, malossi 14/42 primary Polini 14/41 secondary 8.9:1, MXS Hyperhace exhaust, Stage 6 intake, VForce 3 reeds, Stage 6 VHST 26mm flat slide (125mj/35sj/50 slide/d44 needle), Malossi MHR inner rotor 28° advance, Nolgy Hotwire, Mallosi RS3 shock.


Sat Nov 22, 2014 12:55 am
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Location: East Bay CA
Post Re: HPC crank ?'s
Im in the midst of building a CW50 bottom end, Im dropping a Doppler endurance crank and all the parts from my 1990 jog on the CW, but Im going to redo the CVT.

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1990 Yamaha Jog CG50-CW50 swap
1992 Yamaha Jog CY50-stock
2000 Honda Elite SR50-72cc Corsa, Arrow, OKO24, Polini vari, 8.4:1
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1995 Suzuki Intruder VS800
2014 Yamaha FZ-09


Fri Mar 27, 2015 10:03 am
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Joined: Tue Jul 08, 2008 9:16 pm
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Location: Los Angeles area
scooters and mods: 05 Z50 4200 miles, 70cc Polini, 84 jet, Leo Vince zx, Athena Variator, stock clutch w/LV yellow springs and Athena contr
Post Re: HPC crank ?'s
HPC/full circle - as it was explained to me - just means there's extra material there to fill in the extra volume when you put in a 70cc (larger) piston. That increases the compression, so I would think it would increase torque.

"The Stage6 HPC (high primary compression) crankshaft is a full-circle crankshaft, and as such increases primary compression"

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'05 Zuma 50, Athena sport 70cc (12mm piston) with Polini head (.9 squish), B9ES spark plug; timing advanced about 2˚; Yasuni C16 exhaust, Buzzetti kick stand to make room for it (and Stage6 paddock stand after dropping the freaking bike because of the kick stand); stock airbox no snorkel, 5 x 1/2" holes; Stage6 21mm racing PHBG, 45/95/W7 1 lean/40 slide; Polini/Power One 12mm HPC crank; Athena 15/50 gears (also have 14/42s pressed into a gearbox cover, just switched back and like the 15/50s so far); 107mm Malossi Delta clutch, "racing" red springs/lighter "racing" counterweights ± 6800 RPM engagement, Stage6 Kupplungsglocke (bell - the light one); Malossi 6112811 Overrange kit, red contra and 28.2G rollers; VForce 3 reeds; Michelin Bopper tires; back to the stock shock; dual headlight wiring; C3 mirrors; Trailtech TTO tachometer and temp gauge.


Fri Mar 27, 2015 12:39 pm
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Joined: Tue Jul 08, 2008 9:16 pm
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Location: Los Angeles area
scooters and mods: 05 Z50 4200 miles, 70cc Polini, 84 jet, Leo Vince zx, Athena Variator, stock clutch w/LV yellow springs and Athena contr
Post Re: HPC crank ?'s
http://www.mopedarmy.com/wiki/Crank

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'05 Zuma 50, Athena sport 70cc (12mm piston) with Polini head (.9 squish), B9ES spark plug; timing advanced about 2˚; Yasuni C16 exhaust, Buzzetti kick stand to make room for it (and Stage6 paddock stand after dropping the freaking bike because of the kick stand); stock airbox no snorkel, 5 x 1/2" holes; Stage6 21mm racing PHBG, 45/95/W7 1 lean/40 slide; Polini/Power One 12mm HPC crank; Athena 15/50 gears (also have 14/42s pressed into a gearbox cover, just switched back and like the 15/50s so far); 107mm Malossi Delta clutch, "racing" red springs/lighter "racing" counterweights ± 6800 RPM engagement, Stage6 Kupplungsglocke (bell - the light one); Malossi 6112811 Overrange kit, red contra and 28.2G rollers; VForce 3 reeds; Michelin Bopper tires; back to the stock shock; dual headlight wiring; C3 mirrors; Trailtech TTO tachometer and temp gauge.


Fri Mar 27, 2015 12:46 pm
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Post Re: HPC crank ?'s
Your not going to lose any bottom end punch with a HPC crank. Spend the extra cash and do it right the first time. Who knows 6 months down the line you may want a screamer, and all you'll have to do is buy a real pipe. JK

Good luck with the build :cheers:

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2010 Zuma
L/C S6 R/T 95, S6 R/T 44/90 crank, S6 95cc Big Bore Pipe,Trenched and Ported Cases, MVT DD19 Iggy, MXS Intake with KX 85 Reeds, Malossi Overrange , Keihin PWK 35mm carb, UNI air filter, Doppler 14/42, Dr.Pulley HIT Clutch ( 8000 rpm engagement ), Stage6 433 R/T clutch bell, Premix 32-1.

2001 Zuma (Pre-Bug)
MXS Race 70cc, 28mm PWK , S6 Big Valve, SR-1 Crank, S6 R1400 Pipe, Malossi Overrange


Fri Mar 27, 2015 2:16 pm
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Joined: Wed Mar 25, 2015 11:44 pm
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Post Re: HPC crank ?'s
lol I hope i get some extra torque out of my set up with a stuffer crank in place... Thats the reason why I bought it in the first place as of opposed to a stock replacement.

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1990 Yamaha Jog CG50-CW50 swap
1992 Yamaha Jog CY50-stock
2000 Honda Elite SR50-72cc Corsa, Arrow, OKO24, Polini vari, 8.4:1
PocketChangeScooterClub
1995 Suzuki Intruder VS800
2014 Yamaha FZ-09


Fri Mar 27, 2015 9:26 pm
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Joined: Tue Jul 08, 2008 9:16 pm
Posts: 11362
Location: Los Angeles area
scooters and mods: 05 Z50 4200 miles, 70cc Polini, 84 jet, Leo Vince zx, Athena Variator, stock clutch w/LV yellow springs and Athena contr
Post Re: HPC crank ?'s
And you didn't even know that wasn't why you bought it, that the real reason was so you wouldn't break it with high revs.

_________________
'05 Zuma 50, Athena sport 70cc (12mm piston) with Polini head (.9 squish), B9ES spark plug; timing advanced about 2˚; Yasuni C16 exhaust, Buzzetti kick stand to make room for it (and Stage6 paddock stand after dropping the freaking bike because of the kick stand); stock airbox no snorkel, 5 x 1/2" holes; Stage6 21mm racing PHBG, 45/95/W7 1 lean/40 slide; Polini/Power One 12mm HPC crank; Athena 15/50 gears (also have 14/42s pressed into a gearbox cover, just switched back and like the 15/50s so far); 107mm Malossi Delta clutch, "racing" red springs/lighter "racing" counterweights ± 6800 RPM engagement, Stage6 Kupplungsglocke (bell - the light one); Malossi 6112811 Overrange kit, red contra and 28.2G rollers; VForce 3 reeds; Michelin Bopper tires; back to the stock shock; dual headlight wiring; C3 mirrors; Trailtech TTO tachometer and temp gauge.


Fri Mar 27, 2015 11:09 pm
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Joined: Wed Mar 25, 2015 11:44 pm
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Post Re: HPC crank ?'s
Oh. i see. :eng101:

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1990 Yamaha Jog CG50-CW50 swap
1992 Yamaha Jog CY50-stock
2000 Honda Elite SR50-72cc Corsa, Arrow, OKO24, Polini vari, 8.4:1
PocketChangeScooterClub
1995 Suzuki Intruder VS800
2014 Yamaha FZ-09


Sat Mar 28, 2015 10:41 am
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