Sprockets or tires for gearing change

[SIMO]

I plan to use my WR 500 for high speed trail riding and races with a few of my fourstroke thumper friends. I want to know if I should change my current sprocket set 48 rear 13 front or if a different tire would make any difference. Any suggestions on specific sprocket #s would be helpful. I am 250lbs and the bike is otherwise well set up for my wieght. Thanks

 

[SIMO]

I will get a little more detailed on this thread in hopes of a response. The WR is a 92 and I have replaced the carb and fork and shock springs to better suit me. The tires are 5.10-18 IRC rear and 3.00-21 Dunlop front. My question is where do I start for changing the gearing. Can I change my rear rim and tire size or should I just go out and buy a 46/15 sprocket set and chain and hope the front sprocket isn't to big and will fit the bike? Can the bike pull this gearing without becoming a pig? Is there some way of determining my gear ratio at the front sprocket/at the transmission so I can find the actual final gear ratio the engine must pull? Is the jump from 48-13 3.692 secondary reduction ratio to 44-15 2.933 secondary reduction ratio too much change? I love this bike because it has been so reliabe and responds well to the changes I have made. I hate the fact that the four stroke guys do no maintenance and never do top ends but I'm a two stroke fanatic. The snow up here is still 4ft deep but thats the best time to get some quality shop time. Any help would be great. This site kicksa$$.

 

[dirt bike dave]

Sprocket changes are what you want to do. The change from 13/48 to 15/46 would be huge - maybe too much. I would try a 14 tooth front sprocket first before changing anything else. On some bikes, to run a 15 front you have to remove the guard that protects the cases in the event of the chain derailing.

You may have to alter your chain length if you are making big changes to the sprockets.

BTW, the tires that fit the 19" rear rims are generally lower profile than 18" tires, so the overall diameter is similar, and you would get very little if any change in your top speed.

 

[SIMO]

Thank you for the advice. I am still kind of new to the whole MX bike thing. It is alot easier to change and tinker with everything. This is also my first time using a forum like this to exchange infomation. It is amazing that Dirt Bike Dave just saved me the trouble of a 180mi trek to my nearest crappy dealer or the cost of the phone call to some generic monkey wrench mechanic who hates his job. Thanks again Dirt Bike Dave

 

[CaptainObvious]

A new front sprocket will cost you $15-$20. A new rim, that will require a tire, will cost in excess of $200. Moreover, you'll have greater flexability with various sprockets. It's easy to own an assorment of sprockets for the type of ride you are planning.

 

[SIMO]

Thanks RV6junkie! My next mission is to find some good online sprockets and start dreaming of spring.