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pulling the shelf on the ZR900

1365 Views 9 Replies 5 Participants Last post by  Boom
I was just wondering if i would have to re-jet my 900 if i pull the shelf out of my airbox? and can i still trail drive with it out?
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You should not have to re jet if all you do is pull the shelf out of the air box. It will give you more air, but not enough to lean out. Keep in mind, the colder it is, the more air you will draw so watch out for long stretches on a really cold day like 25 to 30 below zero(CELSIUS) I pulled the shelf out of my 900 and put a power breather on and only jetted up one. Power Breather= way more air. Two AC dealers told me that I really didnt even have to jet up with the power breather. I decided to anyways just to be safe. For more specifics just ask. Where do you ride?

Boom Of Manitoulin
Thanks for the info boom,im from Nova Scotia Canada.It hardy ever gets beyond -20 here so i should be safe with my stock jetting.I have another question for you though...do you know what the stock gearing is in the 900??Dealer told me 24/39,I want to drop a couple of teeth because we race 660feet here...so if the dealer is right i'd like to go to 22/39 for a little extra bottom end.
Originally posted by FastCatZR900@Dec 30 2002, 06:51 AM
Dealer told me 24/39,I want to drop a couple of teeth because we race 660feet here...so if the dealer is right i'd like to go to 22/39 for a little extra bottom end.
You may have serious hookup problems. I am thinking of gearing up my 800. Not so much for top end, but I think it has the torque to pull taller gears at the bottom end and spin a lot less. I can't seem to keep the coupled skid from spinning out of the hole (144 studs helped, but didn't cure problem). Marc
I also have 144 studs..we race on a hard packed surface..im not spinning now but it takes about 200 feet before the 900 really starts to pull hard..i thought by gearing down i would get more power down low..i really don't care about top end speed.is the dealer correct in the 24/39 stock gearing...i know im geared high because i have lots of top end speed.thanks for the info Team Arctic.
Hey fast cat, Your stock gearing shouold be what u said, but only if you purchased your sled in the sprimg when they were first introduced. AC changed the stock gearing to 26/41 for the fall model. I have the fall model.

Boom Of Manitoulin( northern Ontario)
Boom is correct, 02.5 was 24/39, 03 is 26/41 except if you have reverse, as I do, then you still have 24/39 which is the only reverse kit Cat has for the 9's.
thanks for the input guys..i have a 03 ZR9..so it must be 26\41..im going to drop a 24 into it and see what happens.Team Arctic did you try tighting the front shock in the rear suspension? when i tightened mine it helped me get more track to the ground when i studded up,giving me alot more traction.
I have a EB 900, What was the reason for the gear change? What is the pro/con for the 24/39 gear selection. Is it just that the 26/41 will give you a little more top end? Also, if you remove the cones, is it going to affect the mid range of the jetting? Currently running 410's 4th clip. 1300'
Top speed on a stock zr 900 was 118.9 in good speed conditions in Northern ontario. I am a big man of 300lbs and can get 115 on my 900 on a GPS(2500 to 3000 ft lake run in excellent conditions ) I compared my GPS To the radar gun and it was pretty much bang on. I now have a power breather and boyesen reeds. this minor change just made my mid range explode with power and acceleration. Holy crap!!! I do not think it did much to my top speed, but I will find out tomorrow, hopefully. After this my next trick will be to change the stock gears from 26/41 to 26/40, this should give me a little more top end speed> I will keep u all posted?

I saw 2 other zr 900s run 127mph with gears, clutching, pipes and reeds. Stock track with chisels studs.
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