[sixpacksewell]

I've got an '08 CRF450R that I'd like to take up to Colorado and ride trails with my brother. Can someone recommend from experience what the most durable clutch and sprocket setup is for low speed/high torque applications. My main concern is heat build-up. Can these water-cooled bikes handle the low speed riding environment?

[JimDirt]

As long as you keep movement going to keep air flow thru the radiators they will work , what i would suggest is changing your coolant to Engine Ice before the trip , this will help lower the operating temps by at least 50 degrees ,also get a 1.6 or 1.8 bar radiator cap , the stock one is 1.1 and will allow coolant to escape when the engine gets even slightly hot , the higher bar cap will allow the engine to get to a higher operating temp without losing the coolant

As far as gearing goes , if your going to be in 1st and 2nd a lot , then i would suggest a 13/52 or 13/53 , the issue with the R's is that 1st to 2nd is a large gap so one will be really low and 2nd will be about right , you will find yourself just starting off in 2nd , but this should be fine , dont forget that gearing down will obviously lower your top speed by a significant amount , with this gearing i will estimate your top speed to be between 55 to 65 , which is plenty fast for tight trails

I have a 13oz flywheel weight on my 02 which equals about a 35oz flywheel (the heaviest you can get) with a 13/52 and my friends that ride it do fine , i can ride it with a 13/50 or 13/51 and do the same as them with the 52 or 53 , what you will find is you will work the clutch a lot , this will add to rising temps , but that is where the Engine Ice helps , i also have a overflow tank off a 250X so if i do overheat some it will keep me from actually losing the coolant

If you are planning on using the bike for mostly trails , i would suggest a heavier flywheel or added flywheel weight , this will help keep you from stalling in most every situation , it wont stop it , but it will definitely help , and i ride mine on the track and have no issues with power

Also , Very Important , dont forget to re-jet for the elevation change or your bike wont even run when you get there

Hoped that helped some

Here is a gear chart to help guide you thru what each gear combination will do , the top numbers are the countershaft sprocket(front) and the numbers to the left side are the rear sprocket sizes , cross the lines for each gear combo and it will give you the ratio it will be


EDIT: Sorry Ken i forgot about the Calculator you have here otherwise i would have linked it

[crfsonly]

you can also compare ratios/rpm/speed with our final drive calculator:

http://crfsonly.com/howto/gearing/motor ... ulator.php

[sixpacksewell]

Thanks a lot guys, I appreciate the info.

[JimDirt]

No Problem , and enjoy your trip !