RPM's

joey fletcher

My Son's Bike
Joined
Sep 12, 2005
Messages
868
Location
Durham, North Carolina
Ride
Recliner
Hey Guys

What speed is shown on your rockets at 3000 rpm. plus what tire are you running???

75 mph @3000 rpms , DS Goodyear F1 Eagle 225x50x16
Going to check mine with a GPS today
 
So I would say you off about 500 rpms there Joey. At 3000 you should be around 80 mph if memory serves me right. The GPS is the best way to correct it. What is the speedo error % on you tune right now.
 
Just got back from a run to Ace hardware.

With the GPS

3000 RPMs showing 75 MPH speedo

Speedo showing 75 mph and GPS showing 72 mph

80 running 76 @ 3300 rpm
 
Tyre size effects your speed at a given RPM but makes no difference to your speedo reading.
 
joey fletcher said:
Just got back from a run to Ace hardware.

With the GPS

3000 RPMs showing 75 MPH speedo

Speedo showing 75 mph and GPS showing 72 mph

80 running 76 @ 3300 rpm
Click to expand...

Joey try changing the speedo adjust to -4% your between 4 and 5 percent you only other problem or inconsistance you will run into is the expeansion of the under inflated car tire. most people running car tires run them down on pressure a little so the faster you go the grow taller. you will have to find a happy medium. SO I would shoot for 4 % and see what the GPS says/ After you make the change save the tune as what ever name it is and add speedo adj. to the title then reload the ecu with it. this will always keep you a master map to go back to if you do something you do not like.
Also a word of warning messing withthe timing can be dangerous. So I would leave that to someone on the dyno. Also you can't really hurt the bike making a tune rich but if you lean one out to much you could burn a valve or piston. Again be carefull.
 
Mr. Warp

I had a Great teacher who guided me through the edit tune. So I know how to change the speed in the ECU. But That is all I have guts to mess with...

What I am trying to find out

Is how much speed to rpm I have lost due to the 225x50 Goodyear F1 eagle tire I am running.

Before My Great teacher showed me to change the speed in the ECU I was apx 10 to 12 mph slow. I would be showing 80 mph on the interstate and everyone was blowing by me.

So what you are saying @ 3000 rpms the Rocket should be running a true 80 mph. reguardless what the speedo shows

Oh, I run 34 psi in the tire when I am going to play... No flex when playing
But normal riding or a trip to the dragon I drop the air pressure down to 26 psi for the softer ride
 
Ok Joey at 3000 rpms in fifth gear you should actually be moving 79.8 mph mathematically speaking.
 
Mr Warp

Thank you.....Thank you

That is what I needed to know..

I will be on the hunt for a rocket rear rim so I can install a taller tire to get the rpms up.

I want to keep this set up...I like being able to get the front wheel up in 3rd gear
 

A taller timer will bring the rpms down as it will not take as many rotations to meet the require suface feet per minute in a mile. This is 5280.
Formula SFPM=(3.1416 x Diameter x RPM) / 12.
 
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