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valves vs. nonvalves on the zr 500

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valves vs. nonvalves on the zr 500

Postby yellow snow » July 19th, 2001, 1:44 pm

I am interested in any input from those of you who have purchased a new 01 zr 500 this past winter. I was wondering how the valved sleds with the sensors in the exhaust pipe run compared to the nonvalved zr 500's. I have ridden the nonvalved 500's and I am considering buying one of the valved sleds but would like to get a little info on how much of a differense there is between these two before doing so. How do these valved sleds run with these 500 xc sp's from polaris?? Thanks for any input it is appreciated.

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valves vs. nonvalves on the zr 500

Postby MxZ MoonZ » July 20th, 2001, 5:58 am

Valves will make your sled accelerate a little bit quicker, and as i look at the zr 600, At #### rpm, you feel a dead spot in the engine, because the valves just popeed open. It read that the valves will make your sled go very fast compared to last years, and the pipe sensor will just keep it running smooth.
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valves vs. nonvalves on the zr 500

Postby Michiganstopcat » July 21st, 2001, 10:07 am

THE VALAVES WILL NOT MAKE THE SLED FASTER ON THE LONG HAUL AS MOONZ STATES.ITS ACTUALLY DOES NOTHING FOR HORSE POWER.BUT IT WILL MAKE IT QUICKER FROM CORNER TO CORNER.THE PIPE SENSOR IS SUPPOSE TO ENSURE THAT THE MOTOR IS ALWAYS RUNNING AT ITS BEST BASED ON THE TEMP OF THE EXHAUST GAS.NO MATTER HOW YOU LOOK AT IT THE VALVED MOTOR IS THE WAY TO GO.
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valves vs. nonvalves on the zr 500

Postby kungfutu » July 23rd, 2001, 5:52 am

Boy, you ride Cat AND your dumb. The two just don't mix. Variable exhaust makes the exhaust port small on bottom end (like a PWC) so you'll have lots more hp down there and good acceleration. Since the port are variable, some variable exaust engines allow a much larger port fully open than non v.e.v. engine, which give more top end power, speed and RPMs. That's why i saw a '02 500 ZR CC beat a 700 XC in a for-fun drag.
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valves vs. nonvalves on the zr 500

Postby kungfutu » July 23rd, 2001, 5:57 am

As for the pipe thing, It does NOT monitor gases. It is looking at the pipe itself and does not go inside the pipe. It give info to the CDI on how it is warming up and changes the ignition to warm up the machine faster and to monitor and change ignition to correct problems (if any) while it is running. There is no feasability in monitoring exhaust gases that far down the pipe.
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valves vs. nonvalves on the zr 500

Postby Michiganstopcat » July 23rd, 2001, 10:07 am

YOU DONT MEASURE EXHAUST GAS TEMP THAT FAR DOWN?WELL SORRY TO TELL YOU BUT,MOST OF THE TIME YOU PLACE YOUR PROBES 9 INCHES FROM THE EXHAUST FLANGE.I KNOW I ASKED D AND D ON WERE TO PLACE MINE.YOUR RIGHT ABOUT THE PROBE NOT MEASUREING THE E.G.T. BUT BASICALL ITS THE SAME THING KEEPING THE PIPE HOT MAKES THE MOTOR RUN THE BEST.YES THE MOTOR WITH VALVES IS QUICKER BUT IT DOESNT PRODUCE ANYMORE H.P. THEN THE NON VALED MOTOR.THAT MY FREIND IS A FACT.AND AS FAR AS BEATING A 700 POLARIS SOUNDS TO ME LIKE THE POLARIS HAD A FOULED PLUG.
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valves vs. nonvalves on the zr 500

Postby alevasseur14 » July 23rd, 2001, 4:38 pm

the polaris 500 would hands down beat the cat. i have raced both the valved and non-valved 500 and they both ate flap. had a 600 chasin my tail lights too...

*This Message was edited on 23-Jul-01 09:39 PM by alevasseur14*
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valves vs. nonvalves on the zr 500

Postby d-man » July 23rd, 2001, 4:58 pm

About hp and exhaust valves... The polaris 700 xc sp received valves early this year and it's hp increased around 7 hp. The 500 xc and 500 xc sp have around a 8 hp difference between the two with the sp having exhaust valves. VEV's (variable exhaust valves) will also increase fuel mileage because the ports open and close based on exhause pressure which in turn lets the engine breathe better and thereby increasing hp somewhat, and fuel mileage.
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valves vs. nonvalves on the zr 500

Postby d-man » July 23rd, 2001, 5:02 pm

If I were you yellow snow, I'd wait until cat comes out with a zr 500 Efi, if you don't want to make any big modifications like pipes. Cat made their EFI systems closed loop so you can't remove the CPU chip. If you put on pipes you need to change the chip, but it sounds like cat has had enough of people burning the engine down and putting the OEM chip back in saying it's a warranty issue and wanting the engine replaced.
And if you have EFI, you don't have to mess around with rejetting for temp and altitude changes.

*This Message was edited on 23-Jul-01 10:03 PM by d-man*
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valves vs. nonvalves on the zr 500

Postby Michiganstopcat » July 23rd, 2001, 5:03 pm

POLARIS SAYS THE H.P. OF THE 700 INCREASED WITH THE VAVLES,POLARIS PERFORMANCE SHOPS WILL TELL YOU DIFFERENT.LIKE I SAID CORNER TO CORNER(WHICH WOULD REALLY MEAN TORQUE)IS INCREASED BUT NOT OVERALL H.P. NUMBERS.THE REASON POLARIS TELLs YOU THE H.P. NUMBER WENT UP IS TO MAKE YOU FEEL BETTER AND TO GET ALL THE SORRY SAPS THAT BOUGHT THE NON VALVED 700 AND 800S TO AGAIN BUY A NEW SLED TO GET WHAT THEY CALL MORE HORSE POWER.ITS BASICALLY A MARKETING PLOY IN THAT POLARIS COULD HAVE HAD A VALVED 700 AND 800 LAST YEAR BUT IT DOESNT MAKE AS MUCH MONEY AS THEY WAY THEY HAVE CHOSE TO DO IT.THATS ALL I HAVE TO SAY ABOUT THAT.

*This Message was edited on 23-Jul-01 10:04 PM by MICHIGANSTOPCAT*
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