Damn another sprocket ?

[thunder1295]

Hello again, just a quick question, I have the factory size sprockets on my 87 FJ 17 in front 41 on the back, I find it revs to high for my liking at highway speeds and I'd like to get little better mileage If I change the front sprocket to an 18 how much would that drop my rpm down..
Thanks I know this is a worn out topic.

Jim

[moonrunnah]

i have changed both my front and rear to an 18/39 i have yet to dirve it (seeing hows its snowy and cold) but if it is like my old ninja i had i went up one in the front and left the back the same and it was about a 800 rpm drop a lot of people here go the 18/39 route so i did that

[thunder1295]

That's a good start dropping 800 rpm's, don't see the motor having to rev that high at a 100 clicks, there's plenty of power in these beasts and they are thirsty to boot.
Thanks for the reply.

Jim

[andyb]

Dude, do the math.  You can use any of the available spreadsheets that are posted in the files section, or you can use websites specifically set for such tasks.

Otherwise, you can figure that going to a 18t front from a 17t front will change the rpm at any given speed to 17/18ths of what it was before.

[thunder1295]

Thanks for pointing that out, great chart..

Jim

[FJmonkey]

You can also use www.gearingcommander.com

[X-Ray]

Yep, its a good idea. I went 18/38 with mine, fairly relaxed on the highway now, but still takes off like a rocket if you want it to,   

[bigbore2]

I have 18/38 on mine, was 17/42 when I bought bike.  Put 18/38 on to take a trip and really needed it there. 18/38 is great on the highway and around town. No problem from a stop, but i miss the ROAR I had with the 17/42. Front would get real light from 5500-9500 rpm. I am going to put the 17/42 back on until I take another road trip. Plus it is easier for me, to set up jetting with the quicker revving gearing as I can feel the changes easier. I need to re-jet as i have gone from a stock airbox with K&N filter [I had the jetting perfect] to UNI filters from Randy. I am so glad to get rid of that damn stock box, what a problem removing and replacing that thing. I even made a special tool to help refit the boots to the carbs when putting back together.