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Discussion Starter · #1 ·
I'm having a problem getting the sled to run right with the HAC .
Does anybody Know anything about the HAC system and how to make it work right, or should I just scrap it and re-jet my carbs to 6000 to 7000 feet. The carbs are VM38's and would I have to do anything else to the carbs? Thanx for any help.
 

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remove the HAC and run the carbs HAC less.
the local dealer removed the HAC from my buds '94 470 summit last season as it was acting up also.
at your elevation the HAC would be nice though.
 

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Discussion Starter · #3 ·
Thanx for the reply..
I did remove the HAC last winter and re-jetted the mains only @320 each. The sled ran great @10,000ft.I had it up to 70mph, but it sucked the gas ,about 3or4 mpg.
 

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I ran a HAC for years with no problems, didn't give much to work with. What is it doing? Do you have it in the air box? Lines hooked up the right way? Is the jetting (all) were it should be for your sled?
Unless you are running a mod there is no need to loose the HAC, they do help if you are changing altitudes.
 

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Discussion Starter · #5 ·
Hi TeamNFG, I have read your reply's for about a year and I quite certain that if anybody can help me you can. The problem I am having is a high end bog. At about 6000rpm, it drops off to about 5000rpm and I have to feather the throttle to get any speed up to about 60mph at about 7000rpm. But, it gets a good holeshot, screaming up to about 50mph and then a major high end bog. All the jets and settings and plumbing are to specifications. I checked many times to ensure this. And I ran new tubes just in case the old ones were damaged. It made no difference. But, when i disconnected the HAC, and rejetted the main jets to 320, it ran like a "raped-ape". It sucked the gas really bad. And the HAC valve is in the airbox and everything is set to standard specifications. Thanx for your help.
 

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my buds 470 would not run good at all and the dealer couldn't diagnose it. once the HAC was bypassed (removed). she purr'd like a kittin.
 

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Originally posted by Lonerider
[br]Hi TeamNFG, I have read your reply's for about a year and I quite certain that if anybody can help me you can. The problem I am having is a high end bog. At about 6000rpm, it drops off to about 5000rpm and I have to feather the throttle to get any speed up to about 60mph at about 7000rpm. But, it gets a good holeshot, screaming up to about 50mph and then a major high end bog. All the jets and settings and plumbing are to specifications. I checked many times to ensure this. And I ran new tubes just in case the old ones were damaged. It made no difference. But, when i disconnected the HAC, and rejetted the main jets to 320, it ran like a "raped-ape". It sucked the gas really bad. And the HAC valve is in the airbox and everything is set to standard specifications. Thanx for your help.
Thanks for the comments

It sounds like you have done everything possible to figure out the issue. Everything you did I was going to suggest checking, thanks for saving me typing or should I say chicken pecking the keyboard.
I would agree with bcsledhead, it sounds like the HAC is failed on you and see if you can find a replacement (first if you have a buddy with a HAC try it to be sure)
I don't think doo has these HACs any more (they haven't been used since 98?) I still have my old one if you arn't able to find one.
I had the same thing happen to me once and found it was a line that came off the carb, but if you are certain all else is good it must be the HAC
If you decide to get rid of the HAC all together there is some mods you must do to the cards (plug some passages) and rejet more than the mains alone.
Let me know how you make out
 

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Discussion Starter · #9 ·
I finally got chance to test out my sled with the changes I made.We 2FT. of snow here in the mile high city last nite. The changes I made was first scrapped the HAC valve, the I change the mains jets from to 300 and pilots to 50. They were 490 mains and 75 pilots. I also plugged the vacuum lines and removed the plugs in the back of the carbs and ran vent line from the float bowls.
It SCREAMS!!! It runs great BUT the gas mileage sucks! 4 or 5 MPG.
if that. Ay help with this problem will be very much appreciated.
Thanx for all the help.
 

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Discussion Starter · #11 ·
No I don't have any pic's .I bought it last year for a ice fishing sled to get me into some backcountry lakes and its been great for that. You are right ,you don't see many of these around. Mine is beat up a little bit. 3 small cracks in the hood. Its been crashed
a few times. I paid $900 for it ,1500 miles and 125 psi.per jug.
 
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