634 hirth jackshaft - ArcticChat.com - Arctic Cat Forum

 
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post #1 of 5 Old 08-02-2009, 09:42 PM Thread Starter
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Sled: ZR 500 2001
ATV: BRUTE FORCE 750 2005
2007 Mileage: 100
building a 1970 634 f/c hirth jackshaft puma replica. Wanted to know if there were any mods I could do to it on the way to wake this motor up a little. It has singe HD and stock exhaust. If I run dual carbs would it make much of a difference. What application should I run. someone told me to take off the ringgear for the starter off the flywheeel, would that throw the motor off? Come on CAT GUYS give me a hand.
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post #2 of 5 Old 08-04-2009, 02:31 AM
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Ring gear won't really be doing much by taking it off, you won't notice it thats for sure. Dual carbs would be OK if you did a dual exhaust or like Cheetah said, a free flowing exhaust. If you mod the intake then you must mod the exhaust usually.
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post #3 of 5 Old 08-04-2009, 03:05 PM Thread Starter
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Sled: ZR 500 2001
ATV: BRUTE FORCE 750 2005
2007 Mileage: 100
What would be the best exhaust to go with?
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post #4 of 5 Old 08-04-2009, 03:15 PM
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For performance a set of tuned pipes would be best, for sound and muscle tone, open megaphone/montana style exhaust pipes.
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post #5 of 5 Old 08-07-2009, 10:55 PM
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Sled: 97 Tcat Aglt, 96Zr580,79/81 Eltigre 6000
10-11 Mileage: 680
09-10 Mileage: 1,200
08-09 Mileage: 1,000
07-08 Mileage: 1,200
06-07 Mileage: 600
ATV: Cannondale Killer V900 HT
I put a 634 in my 70 puma back in the late 70's.

switched it over to a mikuni carb...can't remember the size anymore and put on a set of montana pipes.

other than the above mods engine was stock. It was one cleat throwing son of a gun... fun to ride.

I wouldn't waste my time on the ring gear.... the little bit of added weight will not affect the engines performance.....the 634 was all about torque not rpm.

Good luck on your transformation.

Mike

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