Gearing and Speed

With no tach I've been using my ear as to engine speed, but I've never wound up my R2 all the way to see what it would do with my current gearing (13/47). What I wanted to determine is just what kind of speed I should be able to maintain on the hiway without running the rpm's too high. I found a great web site: www.gearingcommander.com Maybe this has been covered previously, but if not, check it out. They have all the info about the bike and all you have to do is plug in your current tire size and current gearing, and they give you speed in each gear, along with a graph for both stock setup and your current gearing. Pretty slick, and it saved me a lot of hassle trying to back into the calc the old fashioned way. According to the calculator, I should have a theoretical top speed with 13/47 or 89 mph, vs. 93.8 stock. So, 70 mph should be just fine for as long as I want to hold it there. Still, I want to get a 12 O'clock Labs tach, when they are available, to go along with my Speedo DRD. Knowing what is going on down there between my legs is nice (no smart comments!).

Ken

You should be able to do 70mph for the rest of your life without hurting the engine.
I've got 12/47 on mine and do 70 a lot and it ain't blowed up real good just yet. :)

blaisew wrote:

Knowing what is going on down there between my legs is nice (no smart comments!).
Ken

As long as what's going on down there doesn't end up like this!


The bike's best power is up at the top end. I do highway runs often and usually about an hour at a time doing around 70. I stuck on a Stihl tach so I can see what it's doing, and it doesn't mind running there.

The 250x/r engine is basically 1/4 of the R1 engine.

Do not fear rev-ing the bike. It's designed to do that.

You have a rev limiter. That will protect you.

I think the aerodynamics of the bike and your body will prevent you from ever hitting the rev limiter in 6th gear anyway.

Just ride the thing like you stole it and have a blast.

Yesterday I did 3 1/2 hours at 70MPH, with 13-45. It did fine.

a month ago i did an 1800 mile road trip, loaded with camping gear, riding the snot out of it.
gps verified 70-75 all day long, sometimes in 4th gear uphill into a stiff headwind.

don't worry about it!

don't worry about it![/quote]

I sure won't from here out. I didn't realize that these things rev to 10K and that's just the maximum power point!

As a point of personal reference, I'm familiar with Ridgefield. I'm one of the guys that put the timber treating sheds back together after the boiler blew up there some years ago. I spent 10 years up there, and loved it. But, I'm back home to Texas now, leaving only to visit from here on.

Ken

I have 13/47 also with a speedodrd calibrated using gps. I had mine to 86 the other day and did not know that I had it that close to redline. It was wide open and seemed fine at that speed. I have no problems staying at 75 on the bike.

How come the wr250r has more top speed than a wr450f ...apart from having the sixth gear is it because of different gear ratios?
thanks

Different everything. Uses a different engine. That mill is derived from the R1, basically one cylinder cut right off it.

I think the biggest thing (as far as top speed to a WRF or other more dirt oriented machine) is that 5th & 6th are overdrive gears.

The 12Oclock gearing calculator is dead on.

I have 12/48 gearing and I rev limit in 6th right at 81 MPH.

Yes, as already pointed out, this lil motor is a slice off the R1 ... making the piston speed relatively slow for the given rpm ... theoretically, with ample clean oil, fuel, coolant, and other basics, it could run at red-line without harming the motor prematurely. Of course, most people wouldn't, or even couldn't do that ... but just running along at an indicated 70-75mph is certainly no sweat at all for this motor. In fact, you would be better off running in 5th gear at higher rpms (for example) if you were running up against a strong headwind or uphill with the stock gearing.

I still run the stock sprockets because when the wind is neutral or in my favor I can cruise with little effort up passed 80 (again using indicated numbers) and being in San Antonio, there aren't too many places where I need to worry about climbing mountains (unfortunately).

Btw, on a separate note, my last dp bike was the newly revamped 08 klr650 ... nice bike, but it drank oil mysteriously. It caused me to keep a wary eye on the WR²'s oil consumption ... in 2500 miles it hasn't used a drop. Very reassuring for a smaller, higher revving motor to keep things in order. It really is a quality machine!

PooTeeTat wrote:

The 12Oclock gearing calculator is dead on.

I have 12/48 gearing and I rev limit in 6th right at 90 MPH.

thats -1+6 90MPH seems very high for being geared like that, do you have a big bore kit on it? im debating on a +7 or +8 for the rear but im leaving the stock front on cuz i wanna be able to street it also, ill just keep a -1 and a +1 front sprocket on hand for doing different things with it

Oops. I wrote top speed for an older gearing. Post corrected to 81 MPH.

Pinging 6th gear redline.

Wheelies Reeeeeeeeeeeeeeeal easy.

thats more like it lol, thats what im shootin for basically just wheelies and stunt. im gonna go +7 in rear so i have a decent top end

I'm wondering which way to go with gearing if you want more torque and speed down low? You know, 1st through 3rd or 4th gear? Hey, or is better to just leave it stock so that the motor won't have to rev so high at 70-75 MPH or more on the highway?

stock is crap, it wont even pull 6th gear in stock trim. +7 on the rear is awesome, mine rips to 80MPH to top out but 1-5th are way more usable and fun to rip around with. unless your riding highways everyday i would go with around +7. if your riding that much highway that you need to run close to stock your on the wrong bike.

I run 13/47 on both my dirt and my SM wheels. It's a little high for the dirt wheels but seems pretty good for the SM wheels. If I only used the 18/21 wheels I would change the gearing to 13/48 or 50.

Thanks for all the help and opinions from this forum. Based on recomendations I recently installed a new 13/48 combo with a new chain. It feels like this is how the bike should have been geared from the factory.

I also hooked up the SpeedoDRD from 12oclocklabs. The calculator on their page did not work for me at all. I entered the stock gearing and tire size and new gearing and tire size and it gave me a -8.1. The value that worked for me, verified with GPS, was -18.5. It sure is nice to have a working speedometer now.

mine is setup 13/49 and the ratio is like 22.0% but i went by what was off his website adding in the 7.7% factory offset. i gotta check mine with a gps now ya got me wonderin, feels like its dead on tho.

rmax wrote:

Thanks for all the help and opinions from this forum. Based on recomendations I recently installed a new 13/48 combo with a new chain. It feels like this is how the bike should have been geared from the factory.

I also hooked up the SpeedoDRD from 12oclocklabs. The calculator on their page did not work for me at all. I entered the stock gearing and tire size and new gearing and tire size and it gave me a -8.1. The value that worked for me, verified with GPS, was -18.5. It sure is nice to have a working speedometer now.

I have 13/48 and D606's and I installed the SpeedoDRD .. the calculator told me -14.4 .. its close but not exact .. I will have to adjust a little

one more tooth on back for my 49 would not be another 8% difference. did you add in the 7.7% for factory setting being off? 13/48 should be like -20 or -21 or right around there if my 13/49 is -22

Stubbz wrote:

one more tooth on back for my 49 would not be another 8% difference. did you add in the 7.7% for factory setting being off? 13/48 should be like -20 or -21 or right around there if my 13/49 is -22

Think we have a winner.

Stubbz wrote:

one more tooth on back for my 49 would not be another 8% difference. did you add in the 7.7% for factory setting being off? 13/48 should be like -20 or -21 or right around there if my 13/49 is -22

Yeah, I used the online calculator on 12oclocks website and "thought" I put in the 7.7, maybe not .. I should still have the print out at home and will double check tonight.