morrisond
Expert
What is the power Peak on the 2010 Apex? What RPM does Yammie clutch them for out of the factory?
MarkRTX
Expert
10600-10900 area factory clutching is around 10500 to 10700 I believe if I remember right but mine with D&F likes the 10800 to 10900 area for best performance.
morrisond
Expert
So theoretically speaking if the new one is supposed to make it's peak at 10,200 would the reasonable assumption be that maybe it's a 1050 cc, which would make power at a lower RPM?
Maybe the new one was under clutched and was over-revving, as I was seeing 10,700-10,800 on long pulls?
500-600 rpm over could make an 165 hp sled feel like 150-155.
Maybe the new one was under clutched and was over-revving, as I was seeing 10,700-10,800 on long pulls?
500-600 rpm over could make an 165 hp sled feel like 150-155.
MUSKIE
TY 4 Stroke Junkie
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10800 !!
grader
TY 4 Stroke Master
if the sled only had 500km on it than its not even broke in, meaning there is more power left coming. as a demo it could also be clutched to run at 10700 for the press, yet still be capable of pulling much more useful rpm using the gear reduction. there are many possibilities.
Dano
TY 4 Stroke Master
Without any info/specs on any changes, its hard to speculate on RPMs. Nobody knows the reduction ratio between crank and clutch or even if it is different. Probably safe to say that clutches won't be spun faster then 9000 rpm max. People that do know are not telling
morrisond
Expert
I overheard a comment that it should have only been pulling 10,200. I've been doing a little digging. The 1052 Watercraft engine (An Apex engine with 2 mm overbore) makes it's peak at 10,100, Conincidence? The compression ratio on the Watercraft is 11.9:1 and makes 160 hp.
My guess is the clutching may have been slightly off, it's not broken in yet and it didn't have studs. Maybe it is 160-165 hp. It felt strong just not 165ish strong.
Making some wild a**ed assumptions take an stock Apex motor with 73-74 lbs of torque, add in 23.3% for gear reduction, you get about 91 lbs at the primary clutch. Add in 5% for bigger displacement takes you to 96.
Add the Yamacharger you should get 180-185 hp and about 106-107 lbs of torque at the clutch, not 120 but not bad, and maybe enough for me.
What's the compression ratio on the 2010 Apex?
My guess is the clutching may have been slightly off, it's not broken in yet and it didn't have studs. Maybe it is 160-165 hp. It felt strong just not 165ish strong.
Making some wild a**ed assumptions take an stock Apex motor with 73-74 lbs of torque, add in 23.3% for gear reduction, you get about 91 lbs at the primary clutch. Add in 5% for bigger displacement takes you to 96.
Add the Yamacharger you should get 180-185 hp and about 106-107 lbs of torque at the clutch, not 120 but not bad, and maybe enough for me.
What's the compression ratio on the 2010 Apex?
SRXracer
Expert
Rode 200 miles today, and saw a minimum 400 rpm swing depending on conditions we were running in - lose snow, hardpack, road. I think you are trying to read into it a little to far!! 
