Stock 5hp rpm rating

GEM Forum
1

does anyone know what the ge 5hp motor rated or maximum rpm is ? I would assume the factory 25 mph limiter keeps it below max rpm . trying to find out what it’s rated to .

2

4100 RPM

Best not to turn it past 5000.

3

ok Rodney can you help me out ?(or anyone else)
I wanted to calculate motor rpm stock @ 25mph .
here are the parameters:
mph: 25
gear ratio: 12.44
stock tire diameter: 21.40.
did it first manually , then used an online calculator, both answers were close.
answer = 4957 rpms ? is this right ? I have gone over it 5 times and always get the same answer . is there a way to check motor rpm while driving ? something is not right .

calc: mph x inches per mile / min per hour / tire circumference x gear ratio =rpm

25mph x 63360 inches per mile / 60 / 66.25 x 12.44 = 4957

help

4

Think I’d assume it’s 5000RPM based on your math and everything being “stock” and accurate. The MPH might not be 100% accurate for example if you’re relying on the GEM display - mine is “off” about 3MPH for example. If you have a GPS, maybe try using that for a more accurate MPH?

Note sure what you’re attempting to achieve though so maybe my logic is flawed!!

Al

5

Input your
tire diameter
in inches
21.40

              circumfrence     revolutions   revs @ 30mph  revs @ 40 mph
                 in feet        per mile

                       5.60           942.91       4195.96        5594.62

                                                   4879.58        6506.10

                                                   5864.92        7819.89

                                                   6958.70        9278.27
6

Input your tire diameter
tire diameter vs gearbox ratio
in inches
21.50

circumfrence revolutions motor revs per mile revs @ 30mph revs @ 40 mph
in feet per mile
8.9 gear box
5.63 938.53 8352.90 4176.45 5568.60
10.35 gear box
9713.76 4856.88 6475.84
12.44 gearbox
11675.28 5837.64 7783.52
14.76 gearbox
13852.67 6926.33 9235.11

7

that’s why I asked about the stock motor rating. I was trying to calculate what I was spinning my stock motor at with my setup. the number was high . so then I did it as a stock configuration to see what the factory spins them to , and it was no where near what the 4100 rpm rating is .
do you know of any instrument that can measure rpm on these things .

8

I have a spread sheet That calculates RPM based on tire size, that gives RPM for all Ratios at 25, 30, and 40 MPH.

For your 12,44 and Tire size of 21.40

25 MPH 4887.— 30 MPH 5864.— 40MPH 7819.

Email me if you would like a copy. It’s in Lotus 123 but I can provide it in other formats. Please specify.

Note: As you can see - if you Hot Rod these puppys with the 12.44 gear box the RPM’s go way up. One of the reasons Polaris went back to the 10.35 box in 2014

Rodney

9

[quote=OLD HOUSEBOATER;25803]I have a spread sheet That calculates RPM based on tire size, that gives RPM for all Ratios at 25, 30, and 40 MPH.

For your 12,44 and Tire size of 21.40

25 MPH 4887.— 30 MPH 5864.— 40MPH 7819.

Email me if you would like a copy. It’s in Lotus 123 but I can provide it in other formats. Please specify.

Note: As you can see - if you Hot Rod these puppys with the 12.44 gear box the RPM’s go way up. One of the reasons Polaris went back to the 10.35 box in 2014

Rodney[/quote]
wish I had the 10.35 gears , i’ll start looking for a replacement transaxle . maybe someone in a hilly area might want to exchange . thanks for your help.

10

Rudy Yarborough has an 8.9 and is looking to trade for a 12,44 - he is in the hills and wants to climb them. Email me and I will forward your message to him.