Whats the Formula To get to 10k Rpm on 212cc

trinik7597

trinik7597

Active Member
#7
#7
Its really not that hard or expensive to get a Honda to spin 10,000 rpm and make power all the way up the band ... It just depends on the distance you want to do it in and load ...
 
M

moetrout

Active Member
#10
#10
My mini only does 5700 rpm. I want to get it into the 7-8k rpm range. I would think to get to 10k you would need every thing to be very precise and balanced. You would need a high compression head that flows well. Larger valves, heavy valve springs, ported and polish. Light weight piston (wiseco?). Tuned exhaust. Big carb. What else?
 
M

MJL

Active Member
#11
#11
If you want to throw some cash at something, how about a Lifan 200? 8500 rpm out of the box, and a 5 speed transmission that will get you farther, faster than another 1500 RPMs will.
 
noseoil

noseoil

Active Member
#12
#12
You need a cam capable of making power to 10,000, but it will not have the bottom end grunt a torque build will have at lower speeds. To get a nice smooth power curve up to 10,000 you will have to do a lot of work on breathing (intake, exhaust) & are getting into some serious mods & money to make it all come together. Then to be able to run more than once under a load like that will take a lot of thought, planning & precision. Doubtful if this will happen on the first attempt, so plan on doing it a "few" times to get it right. Enough $$$ to buy 3 sets of everything would be my suggestion as a starting point...
 
danford1

danford1

#17
#17
MSPTREX said:
Balance rotating assembly and good flowing head with the right cam for your set up. My drag bike pulls through whole rpm range.
Click to expand...
Do you have a video of that tach under a full power run? It would be interesting to see the rpm and hear the sound as the engine revs through the power band to 10,000 rpm under load.
Thanks
Danford1
 
MSPTREX

MSPTREX

Active Member
#18
#18
danford1 said:
Do you have a video of that tach under a full power run? It would be interesting to see the rpm and hear the sound as the engine revs through the power band to 10,000 rpm under load.
Thanks
Danford1
Click to expand...
No but this year after I refresh the motor maybe i can mount a gopro on it. Not sure how well it will work but i can try.
 
Phil1958

Phil1958

#19
#19
i know i'm an idiot but a 10,000 rpm 212cc engine would need a flow of 212cc x 5000 of air/fuel mix per minute. that's an average flow rate
of 37 cfm. figuring a intake valve opening degree span of 180 degrees over 720 degrees of crankshaft rotation would mean the
the flow rate would need to 720/180 x 37cfm or 148 cfm peak airflow!!!!!! that's assuming 100% volumetric efficiency.

am i anywhere near being close to rational here?????
 
TheDullCarbide

TheDullCarbide

Active Member
#20
#20
Phil1958 said:
i know i'm an idiot but a 10,000 rpm 212cc engine would need a flow of 212cc x 5000 of air/fuel mix per minute. that's an average flow rate
of 37 cfm. figuring a intake valve opening degree span of 180 degrees over 720 degrees of crankshaft rotation would mean the
the flow rate would need to 720/180 x 37cfm or 148 cfm peak airflow!!!!!! that's assuming 100% volumetric efficiency.

am i anywhere near being close to rational here?????
Click to expand...
What about at 260*? And I don't think you could expect 100% VE above 10,000rpm. I think the peak CFM would be around 70 cfm.
 
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