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Discussion Starter · #1 ·
I have a 97 Zrt 600 that I’ve built for snow drags. The heads are cut down and I only run race gas. I tried a 5 degree keyway and the motor is flat and would of rev higher than 8900 rpm. Has anyone tried the 1-3.75 degree keys and found one key worked noticeably better than another?
Thanks
 

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What weights and spring are in primary now?
 

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Discussion Starter · #3 ·
Currently there are 45.5 gram weights with a 170/305 spring and 57/50 helix with a red white spring. I’ve tried from 48-43 grams of weight and the top rpm does not change. The shift speed does with the lighter weights it hits 8900 quickly but doesn’t really accelerate well.
 

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The problem with the 600 is there is not a lot of room for different weight selections. I have asked a few questions on it and got no where. I have found the best results with a 115/295 primary spring. I too went the route of high pre-tention and found mine didn't like it.
If you went that light with the weights its likely too much helix finish angel. Try something like a 44 degree finish. I am running 20/40 gears. I think I will change those out next season. Once your going, there is nothing left. Great for drag racing, not for trails in my opinion.

I think it ran better down low and mid range with stock pipes and 54-55 gram weights with the spring you mentioned at a lower rpm.
 

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I had three of those, and they were Quick and fast. 20/41. Like 55-56g. Cut heads, 3.5 key. Reeds. Stock and DD pipes. Use to embarrass a Lot of bigger sleds.
 

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I ran mine with notched weights, 54-56g, 180/310 primary spring, 5500 rpm engagement, 20/39 gears for 660' only, 23/40 for any distance beyond 660, 57/50 helix, B.M. purple secondary spring, Carb sync is crucial, So is the internal pipe mod, No key or reeds, all stock motor...:buttrock:

BTW...Those 600 triples love heat soaked pipes...Mine would pull sometimes 2-3+ mph in 1000' when doing back to back runs...
 

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Discussion Starter · #7 ·
Even with pipes running in the 9200-9400 rpm range running mid- 50 gram weights? What secondary setups were used? I’m guessing a very shallow finish angle? The cylinders and case is ported with the heads cut right down to 0.035” squish with D&D pipes.
 

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I tried all that and the only way I ever got my 6 to turn those rpms was with 47.5 gram weights and a 115-295 BM spring.

Most set ups you find info on are for stock pipes. For BM or D&D pipes, it's fewer and farther between. Love to hear some set ups. This was not carved in stone but close. Needed more testing. I left off at this after loosing snow:


115/295 spring
47.5 Poo weights
54/44 helix
Cat red/wht. secondary spring.
20/40 gears



Soon to be 23/40. Likely will have to tweak clutching a bit then. I had another set up but it would not shift out all the way so I scraped that idea. It was an AAEN set up. My opinion on that was too much primary final spring tension for the lighter 47.5 weights. I think that was like 160/320 primary if I remember correctly.
 

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Discussion Starter · #9 ·
I’ll try this clutch setup with a 3.5 degree keyway if there is any snow left in the next couple weeks. I have almost all those components already. The sled has 144 chisels in it so I have to trailer it somewhere to try it out.
All this makes me wonder what guys running the black magic 10200 pipes used for clutching.......

Thanks for the help everyone.
 

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If you don't mind, please post your findings. Would love to know.
 

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Discussion Starter · #11 ·
Did some testing this afternoon. Since we’re loosing snow quickly here the field was rough and progressively got worse.
Started with;

Black magic black/green
10mb weights ( the heel was ground so they weighed in at 46.5 grams)
57/50 helix
Red/white.
This setup revved 9200. Had a friend with me and beat his sled by one length. It did not feel like it was shifting out hard at all.

Changed the primary to;
10a weights (52 grams)
Cat orange/white
Left the secondary the same.

Although this setup only revved to 9000 it was a huge improvement. I was now putting a 6 sled gap on my friend in this short field. The engagement is too low and these weights will definitely require notching. Got the radar gun out and this setup was pulling a consistent 75 mph in the short field.
Changed the secondary to;
60/40
Black magic purple.

Two runs on the gun in the same distance 80 and 81mph revving around 9100 but it was tough to tell because the field was pretty rough at this point.

Although this setup seems to work alright it can use some refining. I hope this helps others.
 

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Thanks for the response. I will have to try that or something similar when snow arrives again. Thank you again!! What gears were you running in it? 10 a weights I thought were 55 grams.
 

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OK, thanks!
 

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I had a '96 ZRT600. 54.5 gr , Or/wh primary, clutch had 1 spider shim out, 57/50, red/wh sec spring in hole #2 (soft) with roller cover. I think it had 23/40 gearing. Stock pipes tightly sealed (a MUST!), VF II reeds, 320 mjs. Would run 8400-8500 rpms, but over-rev to almost 9k on a good long run. Absolutely quick and fast sled.
 

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I had three of those, and they were Quick and fast. 20/41. Like 55-56g. Cut heads, 3.5 key. Reeds. Stock and DD pipes. Use to embarrass a Lot of bigger sleds.
I ran mine with notched weights, 54-56g, 180/310 primary spring, 5500 rpm engagement, 20/39 gears for 660' only, 23/40 for any distance beyond 660, 57/50 helix, B.M. purple secondary spring, Carb sync is crucial, So is the internal pipe mod, No key or reeds, all stock motor...:buttrock:

BTW...Those 600 triples love heat soaked pipes...Mine would pull sometimes 2-3+ mph in 1000' when doing back to back runs...

Been playing with mine. Some reeds and carb work and relocating the exhaust bracket under the BM pipes.



Question I have for you two guys is,... you ran 54/55/56 gram weights spinning 9200 rpms?? I am trying to get 9200 with 23/40 gears and 54 grams. Wonder if that is obtainable?
 

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On a 2000 model year lifting the cylinders and cutting the heads an extra .010" what timing key should I use for trail side gas? Squish gap should be about .059". Are these 600's ignition as big a pig as there older big block brothers?
 

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Been playing with mine. Some reeds and carb work and relocating the exhaust bracket under the BM pipes.



Question I have for you two guys is,... you ran 54/55/56 gram weights spinning 9200 rpms?? I am trying to get 9200 with 23/40 gears and 54 grams. Wonder if that is obtainable?
Only ran my sled with stock pipes @ 8350...
Contact a member here named "Auggie" he also hangs out at A-Chat...He was Tim Bergs right hand man @ Black Magic...He did most of the sled tuning there for their products. He might remember what worked the best...My personal experience with the 600 motor was they did not respond well to aftermarket pipes for TRAIL riding...
 

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On a 2000 model year lifting the cylinders and cutting the heads an extra .010" what timing key should I use for trail side gas? Squish gap should be about .059". Are these 600's ignition as big a pig as there older big block brothers?
My memory says cutting the head on those 600's more than 0.10-0.15 will require 100+ octane fuel...My opinion on timing keys is this...For the 2 hp gain, they can cause severe damage with poor pump gas from some remote gas station...IMO not worth the chance...
 

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That's true. 20 years ago.....gas had more gas and less crap in it. I had D+D pipes in 97 or 98, man I don't remember them revving 9k+. I remember talking to Auggie, and I use to get a lot of stuff from Tim. Never ran race fuel, just blipped the throttle a lot....didn't trail ride much when jetted lean with the 3.5 key and tight heads.
 
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