12 tooth sproket on my R?!?!?!?!?

[stocktires]

I have an 86 250r with 13/39 gearing. The chain and sprokets are in not bad condition. My R has way too much top-end and I want more bottom end! My question is with a 12 tooth front sproket will my chain be really loose and be easier to pop? I have heard that it is bad to buy one sproket at a time and the best way to go is to buy all new chain and sprokets at one time, is this true? Do you think i should ge ta 12 tooth sproket?

p.s. I ride MX

[Guy400]

Of course, as always, there's pluses and minuses to what you want to do. Option 1 is to just run a 12 tooth. You will have to tighten your chain but assuming that your chain isn't all stretched out you should have enough adjustment. That's your cheapest alternative. The down side of this is that they say the 12 tooth puts a little more stress on the chain and causes quicker wear since it's such a tight turn to make. I've been running my 12 tooth for about 7-1/2 months without having to adjust my chain for stretch and don't see any noticeable wear on it. Your other option (more costly I might add) is to leave the 13 tooth on up front and run a 42 rear. This will give you the same effective gear ratio but won't stress the chain like the 12 tooth. The downside of this is that you've got to buy a more expensive rear sprocket and a new chain because I really doubt your chain has enough slack in it to make up for a +3 tooth rear sprocket. Another thing to watch out for is rear sprocket to swingarm skid plate clearance. This may become very tight but you can simply shim it out a little with a washer or two. I've never heard of having to change both sprockets and chain all at once. If the teeth on the sprocket you plan on leaving is still in good shape (not sharpened or curled) than there's no sense in buying a new one. I'm often skeptical about these recommendations, seems like a convenient way for chain/sprocket companies to get you to spend your money.

I understand what you mean about too much top end. My '92 LT250R had just about every engine mod you could buy (the only thing stock were the cases, crank and rod). With that much motor and 6 speeds there was just too much on top and not as much as I wanted on the bottom. Back when I had that bike I was a hill climber. I ended up running a 12 front and 42 rear for bottom end that I liked. Still found enough top end to get me in trouble.

[stocktires]

thanx for all your help guy, My chain is in great shape (krause/sidewinder chain) and my Sproket are pretty good too, there like 1 1/2 years old but they're sidewinder sprokets and look about a month old!!!! My R has serious top-end, i've never wound it out in 6th yet! I dont wana spend a whole lot of money and time because i just got my R back together and my wrist is finally healed (was broken, in kast for 3 months) So i wana ride, But i never use 6th and very rarely use 5th. I run like 2nd-4th all the time. So im probably gonna try the 12 tooth, thanx again