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Discussion Starter #1
My 2006 Brute Force 650 can only get to 59mph. I have 27's swamplites in the front, and 29's in the back. overall the machine weighs stock 604 pounds, the guy I bought it from said he rejetted it with bigger jets, but the only thing to come from that is cranking problems.

Can someone please tell me why it go's so slow, or is that natural for a Brute?
 

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You've got 4" bigger tires on the back, and you're still showing 59mph?? That's a 16% increase in tire size. 59 is 68mph. I'd call that fast.
Check with a GPS to get the real MPH.
I hope you're not using 4x4 unless you're in the really sloppy stuff, and at low speeds, considering the difference in tire sizes.
Your machine weighs closer to 700lbs with fluids and tires.
 

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Discussion Starter #3
My friend drove it in 4wd without knowing for like 8min. what will that do to it?
 

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Yeah I'd def. consider atleast matching the tires on the back with the front. You should never put different size tires on the front and back if you never use 4wd. I think that could really mess up your bike...
 

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probably nothing unless the wheels were under restriction ie: mud or snow. If your just going at a gradual speed in 4wd it probably did nothing...
 

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My friend drove it in 4wd without knowing for like 8min. what will that do to it?
Don't worry about it. It will cause extra wear, but it would take many hours to accumulate.
If it's driven on any slippery surface, such as mud or snow, the wear will be even less.
 

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I'd sell those year tires and match the front ones... You'll see a speed increase and you don't have to worry about using 4wd with the mix match
 

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Discussion Starter #8
the rear tires are putting strain on it?
 

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well you said the fronts are 27's... that's 2 sizes up from stock.

the rears are 29's and 4 sizes bigger then stock...

obviously the rears are heavier and slow you down more then the fronts...

I'd just get 2 rear 27's and sell the 29's... done and done
 

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the rear tires are putting strain on it?
Lets go back to basics:
1. Heavy tires put extra strain on the drivetrain, and will reduce performance. Now, on to the stuff that is affecting your machine specifically.
2. The gear ratios are the same front-to-back, which means you have to run the same diameter tire front and back. A difference in diameter means a difference in circumference, which means a bigger tire will travel further than a smaller tire. In your case, the rear tires are trying travel to 16% further than the rear tires, so for every mile (5280ft) the front tires travel, the rear tires have traveled 6125ft. Obviously, they haven't traveled a different distance, so the tires are slipping/scuffing for the 845 foot difference. This difference causes a great strain on the drivetrain, wearing gears, bearings, and of course, tires.
3. The difference in the weight of the tires between the front and back have nothing to do with what's happening; it's the diameter.
4. If it's not in 4x4, it doesn't matter.
 

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as far as top speed goes the bigger main jets may be hurting your top speed or at least wasting gas. most who need bigger mains have significant mods, and or are in colder climates. and the other huge issue is the tires, my 650 will go 65 with stock tires, 62 with 26in mudlights, and i tried the 27in swamplights and it was about 59 or 60. they are a very heavy tire. 29s would be that much worse. basically if you want big tires forget about top speed they are contradicting mods
 
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