I have a friend with an Automatic AC 650. He had a AC 500 and won many pulls with it. I asked him how was it going with the new AC 650 and he replied great but I can't win any pulls with it. It seems weak in the mid range too.
I thought I would visit here and ask you folks about it. What does he need to check or mod to be competitive in sanctioned pulls? What have you folks been discovering about the machine? Is this normal?

 

to be competitive i believe he would have to reclutch it just to tighten the belt up i know i am going through this burning belts in low range thing right now i am sure he is like me misses his 500 stock setup with the duramatic tranny and the clutching and it should do better then his 500 anyways i know mine has more power but maybe in a pulling contest that can be a problem having to much power spinning out and losing traction tell him to throw a dynatek cdi on it to help low end and mid range and also tell him good luck it is a great machine well it will be if a person makes adjustments to it

 

the 650 cat might have too much power causing wheelspin.dynatek plus any other tires but the stock ones might help

 

This is most likely the problem. I'm speeking from experience. Both my wife and I have the AC 650's. We love pulling. As a matter of fact, I built a pulling sled for our ATV club. We use to have 600 Grizzly's and did pretty well with them. When we switched over to the AC's, we did lousy at the first pull we did. And both machines had the black spring/shim work done to the clutches. I felt that the machines weren't reving up like they should. So back to the chat rooms. Here's the problem. These things can't breath with the tiny snorkel they come with from the factory. So I was able to get a 90 deg, 2 1/4 I.D. radiator hose from NAPA (#7905) that fits perfectly over the snub on the air box, rejetted to 140's (Kehin jet sizes) one shim under the needles, and this thing really woke up. To put it to the test, at the next pull we had. I had my machine, with this mod, running on stock tires, and we borrowed some Goodyear Mudrunners for the wifes machine, but I didn't get the intake mods done on her machine yet. I beat her in both the 2WD and 4wd classes by about 15 feet. I also beet a BF running Bighorns, and a 700 Prarie. By next year, we'll see how much the Dynatech unit will add. I posted this mod on other boards and heard others say they cant find this number from NAPA, but have been able to locate one anyway. This hose fits great. All you need to do is, cut the short end off, leaving just enough to allow you to put the clamp on for the air box snub. Then cut the long end off at whatever height you want. I left it as long as possible to fit under the cover, but cut it at an angle, lower in front, so it can get a good air flow from the factory air passage. As it is, I haven't changed the overall height of the snorkel, so it should beable to go as deep in water as the factory snorkel did. I'll post some pics as soon as I figure out how. Ok, see if this works.

 

Here is a # that I found for a Gates hose that is supposed to be the same as the NAPA one,20431.

What elevation are you at?700 or so?I'm below 500' and I am in the process of doing this mod,will the 140 jets work for me,IYO??What about shims,whats the deal with them,is that something else I have to ask for?I want to order everything tomorrow to try and be on the trails by the weekend.Please help a fello quader,this sh(*& scares me.

 

Diginit, I clicked on the link that you posted and it says,
An error has occurred.
You do not appear to be the owner of this album.
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I am very interested in intalling this mod on my rig. Please try to post your pictures or e-mail them to me.

 

Heyyou, I'd get the shims. There easy to install. Remove the carb diaphram covers (on the left side), remove the spring, plastic spring seat, and the needle. Place one shim onto each of the needles, and reinstall everything. Watch out for the little vent hole on the bottom of the diaphram. Make sure the legs on the spring seat don't block this hole. The needles meter fuel flow from 1/4 to about 3/4 throttle. It's possible you may not need them. I haven't tried running with out them. I put two in at first and noticed a slight stumble of idle, so I took one out and it seems to run fine, so I quit there. The 140's should be the right ones for your elevation.
Catskinner, I have no idea why you can't get the pics. It took me a couple of attempts to get them up. I can get them when I click on the link. I'd like to know if anybody else is having trouble getting the pics. If there is a problem, I'd appreicate some help on what I'm doing wrong.

 

Dig,
I tried the link & got an error also. Could you email me the pic? Greenblud1@aol.com

Thanks,
Jeff

 

Thanks Diginit,I have all my stuff on the way,with some luck I'll have it all together by the weekend.

 

Ok, since I'm having trouble getting the link to work, I posted the pics in the "My Photo" section. Since I've posted these pics on other forums, and since I get them when I click on the link, can sombody give me a clue why it's not working?. I'm waiting for my 10 year old to show me how my computer works>[img]i/expressions/face-icon-small-confused.gif[/img]