Some questions for you experts! I have an AC 375 4x4.

Jetting:

I pulled out my new spark plug that I put in at the 100 mile service, and after putting an additional 100 miles on it. It was black as coal. I checked my Main jet and it was a 150. I went to the dealer today and ordered a 142, 145, and 147. Which jet should I start with first? I usually ride between 500 and 3100 feet.

I also had to switch to reserve after 53 miles, I sort of felt like I was eating gas too quickly.

Spark Plugs:

For informational purposes my AC 375 had a DENSO U22ESR plug in it, that crosses to the NGK CR7E. I run nothing but premium gas (Shell 93 octane). I bought a couple of NGK CR8E's at my dealer to try them as well. Anything I should look out for here?

Tires:

Ok, for the first bad news I have on my quad. The Dunlop tires that come on the new AC's this year flat out SUCK! yes, they actually passed suck about five miles back and proceeded directly to BLOW!
I noticed my tread patterns left in the dirt/mud were very disheveled and unapparent compared to the stock tires on other quads. The dunlops don't self clean very well, are extremely soft, and the tread depth is weak! Those of you with 489's, be thrilled compared to the dunlops. The dunlops almost make me feel like that are way too low-impact my application which is trial riding for the most part. So, that being said, I'm gonna upgrade my tires. I like the 589's and the Goodyear Mudrunners. On the 2002's what size tire should I go with? 26 or 27? I'm not as conecerned about ground clearnce gains as I am the tire rubbing my shock or slamming against my wheel wells. What are your experiences with the 2002 and larger tires?

Durmatic tranny maintenance:

I saw cowboy's post about cleaning removing the V-belt cover and spraying it with Gunk Engine Brite to clean it out. How often should one do this? Will I need a new gasket for the cover every time I do it? What else should I do to keep the vbelt in good shape?

Air Filter:

Any special tricks for cleaning my air filter? What type of oil should I use?



Thanks for all of your help in advance!

EtherNut

 

On the jet, I would go with the 145. If it's really black this should do the trick. Your milege will go way up.

Don't waste your money on premium gas. Regular is what the engine is designed to use. Nothing isd gained by using premium.

Dunlops suck big time, what else can you say. I'd stay with the stock tire sizes, just go to a better tire. The 489's, or some Blackwaters, etc.

The gasket for the Transmisson is made of metal. as long as you're careful when you remove the cover and don't kink the gasket you should be ok for a very long time. Clean the tranny case ANYTIME you get muddy water ingested into it. Other wise about every 500 miles should be ok.

For cleaning the air filter I have discovered something that works miracles. It's called greased lightning. They sell it in teh automotive section of WalMart and K Mart. Use it with water and it cleans the filters right up. Get a good quality areosol spray filter oil. Do Not use regular motor oil to oil your filter. Belray makes some good filter oil. You can also buy it by the quart and use a plastic bag to coat the filter. If your filter is blue get the red oil, it makes it easy to see when it's fully coated

That should cover it.

 

I would start with the 147 main jet.so not to lean it out to much.then if the plug is still black,try the 145.leaning out to much will result in a hole in the piston.
I would stay with the standard plug unless it is fouling.
As for tires I like the GBC Dirt Devils.They are awesome in the mud.can't comment on the performance of the 589's or Mudrunner's but looking at the tread pattern,I suppose they would give a bumpy ride at low speeds.
When cleaning the air filter dont twist or wring it out you might say or it lose its orginal shape just squeeze it between two rags.

 

As far as tires go after mounting them be sure to take the rear suspension through its maximum articulation. The only place it will rub is on the rear shock when flexing one rear up the other rear down. I had to use spacers with my 02 500 and 27x11x12 589s. I have seen 25" 589s on a 375 with no spacers and no problems. You shouldn't have any trouble with the belt unless you take on water, just check it ever so often. I have a spare air filter that I just take the dirty one out and replace with clean one. Then you don't have to wait on it to dry before you oil and ride. Just keep it clean and oiled good it is the life of your ride.

 

I was thinking about putting 27X9X12 589's all the way around on my 375. That way I get the benefits of the larger tires and dont have to worry about the 27X11X12 hitting my shocks. Does this sound like a decent option? I'd be going up an inch in width in the front and going down and inch in width in the rear. Your thoughts anyone? I'd sort of think that with the 589 27X9X12's in the rear, I'd still have TONS more traction that with the dunlop KT 25X10X12.

EtherNut

 

The plug change you are trying may not help as you are going to a colder plug. The CR8E is colder than a CR7E, you may want to try a CR6E. I switched from a CR6E last winter to a CR8E just to see what the change would be. The bike lost some throttle response and burned fuel like crazy. It also made the plug go black. As far as octane goes use the lowest number that you can as long as you don't get any spark knock. Mfg reccomends Min Octane 87. As the weather gets hotter you may need to switch to a higher grade. There is no more power made from high octane fuel, in fact I think Andy B. did a post on this that said that there was theoretically less energy available from higher octane fuel due to the more controlled burn.

Cheers Jim

 

Hey Ethernut, I totally agree with you on the tires for 2002. What the hell were they thinking. They used to at least use Titan 489's, not the best, but descent for stock. Those dunlops are exactly the reason, I never road 1 foot with them on. Immediately, took them off, then ordered Titan 589 M/T's and M/S's. What was Arctic Cat thinking?[img]i/expressions/face-icon-small-shocked.gif[/img]

 

Oh yeh, as far as size goes....

In order to avoid any of the following potential problems:
* Ball Joint
* C/V Joint
* Rubbing
* Bottoming out
* Moving things out of the way
* Loosing noticable torque
* Speedo too far off
* Buying spacers
* Buying lifts

Call me paranoid, I know there are guys out there with successful 27" and 28" implementations, but they got to be wearing their ball & C/V joints faster than normal. In talking with my dealers mechanic, he recommended using the 1" rule. Stay within 1" of the factory heighth, and 1" of the factory width, and the above listed things should be OK. So I have 26x9x12 in the front and 26x12x12 in the rear. This is just my .02 on this make of ATV.

good luck!

 

I also like the goodyears but they are a little rich for my blood so I've decided on the 589's. How do the 589's feel when on a hard surface (road) at say 40 MPH.... Are they a rough tire? What about my thoughts on doing the 9's all the way around? I do want to keep the weight down and am sort of concerned about the 12's. Should I be concerned? I wish they had 26X11X12's ... :-) Should I go with the A/T or the M/T's? Where is the chepaest place to buy them?

Thanks again!

EtherNut

 

Well as far as tires go I would recommend the GBC gators. I have the 27x10x12 on front and the 27x12x12 on rear. The gators are not as heavy as some of the other tires. I love mine they are smooth as silk and have been excellent in all conditions. You can get them in factory sizes or even the 1" rule. I never heard that so I don't know if that is fact or just someone's opinion. I haven't noticed any problems with mine at all, but only time will tell. On the spark plug, I just switched from a CR8E back to a CR6E. It has made a ton of difference. I continually fouled out the 8E plug. Since switching back I have had no problems. I don't know about the jetting. I live in Texas and I don't know if changing the jetting would help me at all. I noticed a drop in fuel mileage when I got the bigger tires, but I expected that. Don't be scared to look at the Gator tires, I guarantee you will like them. They are VERY similar to the mudbugs and they have gotten great reviews for a while. In fact in Highlifters all-around tire test early this year the mudbugs won. This was before the Gator was introduced but while talking to the guys at Highlifter they told me they can't keep the gators in stock. They will highly recommend the tire also.



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