I was wondering what the best sprocket tooth combination would be on my LT. I have quite a few motor mods and was wondering if the stock sprockets might be hurting the performance, although it is still very fast. Any comments would be greatly appreciated.


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86' LT250R

 

It depends on what kind of speed you want. If they are stock, then that means you probably have 13 in the front and 34 in the rear? The thirteen will give you more top end speed. But if you drop a tooth up front and add in the rear, you will gain more bottom end torque. And vise-a-versa.
......Freddie

 

According to all of my catalogs that sell sprockets the stock gearing for a LT250R is 12/42. I am sure it could pull considerably higher gearing than that stock. Since you have yours modified you can definitely use higher gearing. What sprockets do you have now?

 

I have 12/42 on it right now. I race flat drags and motocross. I am looking for the best combination for each. I am running 20 inch shredders on the rear.

Thanks for the help
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86 LT250R

 

I don't think you'll find a combination that works for both applications. I hate to tell you, but you're just going to have to buy some and try them all. Each tooth larger on the front is equivalent to 3.5 teeth smaller on the rear and vice versa. The larger the front sprocket and smaller rear will result in higher top speed but you will lose bottom end power. The smaller the front/larger rear is just the opposite.

With your sprocket combination, go buy an 11 tooth and 13 tooth front sprockets since they are much cheaper and won't hurt your pocketbook near as bad if you never use them. Either way, it will make a dramatic difference in the way it performs. If the 11 tooth is too low geared and 12 teeth is too high, buy yourself a 40 tooth rear and run the 12 tooth front. That will be a medium between the two. This will probably work best for MX and not flat line racing. You would run out of speed too soon.

Now for straight racing, not MX, try the 13 tooth front and 42 tooth rear. If your engine has a hard time pulling this combo, put the 40 tooth rear on and it will split the difference between the 12/42 and 13/42. It's all a matter of trial and error. There is no one combo that works great for everything. The factories put the 12/42 on there because it was a medium that worked well in most/all applications.

The ratio's of these all are as follows:

12/42 = 1/3.5 Stock

11/42 = 1/3.8
11/40 = 1/3.6
12/40 = 1/3.3
13/42 = 1/3.2
13/40 = 1/3.0

Basically the higher the number (1/3.8) will give you more off the line, but less top end. The 11/42 combination will not have as much top speed as the 13/40, but will launch off the line quicker and be easier to keep your revs up.

There, now is that clear as mud?
I hope I didn't confuse you more than before.

Kyle