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I ran my 01 800 ZR on a lake today and it hit 112 MPH on a radar gun. The conditions were ok, with 1 inch of packed snow but warm 35 degree temperatures. The 112 MPH was OK, but it seemed a bit slow considering the sled has 140 HP. My brothers completely stock 1999 700 MACH 1 went 122 MPH and it is also 140 HP.

My sled is all stock and seems to be running out of gearing on the big end and overreving, taking the engine out of the power band. Has anyone else experienced this? When I caculate what the stock gearing and 7400 RPM will give me for top speed, I come out with 109 MPH. Has anyone changed their gearing to try and get more top speed?

So far I am not that impressed with my new (new to me) 800 ZR's power, I have not been able to trail ride it yet. My old sled (which I still own) is a 1993 T-cat that is clutched and jetted correctly. The T-cat easily out accelerates the 800 ZR to 100 MPH (5-7 sled lengths) and then keeps on going.

One other note, My 800 ZR was faster then two other 800 ZR's that were also present, so I know my ZR is not running any worse then other ZR's.

Thanks
 

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Im not sure what the gearing is in the 800's but you could try a 1 or 2 tooth increase on the top sprocket.It will give you more top end..but less on bottom.Also your track may be to tight..loosen it of just until it won't rachet the track..i did this to my ZRT600 and it made a difference on top end.But if your studded you will have to leave it tight.
 

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The stock gearing in the ZR800 is 24/39 (1.625 ratio). The most common gear change for top end improvement is to switch to the 25/38 (1.52 ratio) combination which uses the same 72 pitch chain. 25/38 will add several mph to the top end and also has been said to actually help the holeshot if you are experiencing track spin because the taller ratio loads the engine more allowing a better hook-up.
You may also want to investigate aftermarket clutching if you have the stock set-up. If you are using stock clutching you may also want to simply try the 2002 ZR800 clutching spec. It is improved over the first year ZR8 clutching set-up.
Good Luck!
 

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Originally posted by MUSKOKA800@Dec 30 2002, 01:42 PM
25/38 will add several mph to the top end and also has been said to actually help the holeshot if you are experiencing track spin because the taller ratio loads the engine more allowing a better hook-up.
Musk, do you anyone who actually made this change? I am thinking of doing this due to track spin out of the hole. Marc
 

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25/38 is very popular with these sleds. You got to keep the stock motor at 7400/7500 rpm during the pull with over rev only 100/105 mph & up. Make sure you get max shift-out.

Stock gears should give 114 mph @ 7700 rpm and a 1.12 shift-out. 25/38 should give 121.9 mph with 7700 rpm and 1.12 shift-out.

Realize that track windage may impede top speed also 1.12 shift-out is hard to get. Clutching may (will) help.

Also the T-kitty motor pulls beyond 8K so with the same gearing it is going to go faster.

BobCat
 
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