[bjankuski]

I have a 2001 ZR-800 that I would like to convert to a ZR-900. If I purchase the ZR-900 jugs, pistons and head, can I reuse the 800 Y-pipe, expansion chamber, and power valves (recutting them to match the new piston size)? Can I use the 800 CDI box or do I need the 900 CDI?

Thanks for the help

 

[catspaz8]

I did the same conversion last year, I bought a 03' cdi, 900 powervalves, but cutting them is easier and cheaper, you can also shim them out with washers. I also bought the 900 y-pipe and stock exhaust cheap, like $75.00 for both. I was told that I NEEDED to have the y-pipe.
I talked with Kelsey at RKtek cause I have his head and mentioned that the zr800 pipe would work, try getting ahold oh him at www.Torquelineproducts.com. Changed the gearing to 41/26 ason the 03' 900 and added a 1.5" track. Couldn't find anything I couldn't beat when finished.

Sell your 800 topend for $400.00 os so along with your cdi and save some of the money you spent on the 900.

I had a Black Magic Single on it, but it ran bettter with the stock 900 pipe and PPP can I have from my 800.

I also changed the carbs to 03' 900 spec's but put a different needle to handle a lean midrange on the 03' 900 mapping. I could that needle number if you need it.

Like I said, I could out run any F7 and REV I could find.

 

[bjankuski]

What needle did you change to? I was planning to start my jetting at the 03 900 set-up and then make changes but if you have already done that I would like to know what you changed to, so I could use it as a reference.

Thanks

 

[hugh]

The needles you want are 9DFH-58's part #6506-200. A 1010 with hot ignition may need 9DFH-56 part #6506-186.

 

[catspaz8]

my 900 runs the 26/41 with 74pitch chain combination that came on the 03's with 74grs, a yellow/white with 62/54 and red/white for the stock engine with V-Force. The carburetion was identical. I always ran 9DFH-58 needles to fatten the midrange(hot spot on stock ignitions) versus the -59's that come stock. They are 2.58mm thick at the taper and allow more fuel past at partial throttle, they also list a 2.56 needle in the performance manual. Don't get confused by the numbers as 99% of people do; any number after the letters is just a lot number and any number after the 58 or 59 is needle clip position.
I now have 76 gram weights in the drive clutch and will be leaning it down a bit this year, I have 420's in it now and will trying 410's, maybe 400's, but that is with a RKtek Head and Swain Teck Coated pistons. I also have a new 1.4" track that I will add minimal picks (96) for a little better grip on icy turns and twisty's. Now all we need is SNOW!!!! :smiley-faces7: