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The airbox being off is a pretty big restriction lifted off and the machine is designed to run with it. I would just throw out the cheap carb before it gives you anymore headache and try the mikuni again with the airbox. Did you change any setting on the jet needle?

 

Yes I rebuild the carb with a kit and put the new needle in that came with it. Well I figured for 35 bucks it was worth a try with the new carb.

 

I will try that

 

What position is the e clip at on the needle and what position was the old one? Make sure they’re the same size. The Chinese carbs will NEVER work well on anything larger than 90cc’s.

 

Ok I put the old carb back on and put the airbag back also . It is still popping and now I can't get it to rev real high. I didn't change the fuel pump. Could it be stavin for gas maybe?

 

As far as the e clip don't remember where it was before I rebuild it. Is there a certain spot it's suppose to be

 

The jet needle and pilot jet makes all the difference in the throttle area you’re describing. It’s an adjustment that raises or lowers the needle out of the main jet to let more or less fuel in at high rpms. Start with it in the middle position and move up or down and see how it does. Also double check that the oem needle and the new one are the same size. Usually rebuild kits come with jets. Did you change the original ones with new ones? If so what size are they?

 

Make sure the needle has the spacers in this orientation. Bring the air screw out to 1 1/2 turns from lightly seated. That and the middle position on the needle are base settings for tuning a carb.

 

@Scrappy507 - not quite right

The following long post is for those who want to learn and be better at repairing precise critical components necessary for acceptable engine performance...............

The pilot jet is for idle - it works in conjunction with the fuel screw to set the mixture for idle - common misconception; the fuel screw has a 'spec' setting and putting in a bigger pilot jet improves throttle response. That's wrong, if a larger pilot jet is installed, it just means the idle fuel screw will not have to be turned out as far to set the idle mixture.

The needle in the slide rises and falls with the slide pulling the needle out of the needle jet (#6) - the needle jet is responsible for fuel delivery into the air stream between idle and 3/4 throttle - above 3/4 throttle it's basically all main jet - the main jet can be removed and the engine will operate normally until the slide needle is far enough out of the needle jet that fuel control is lost and the engine guns excessively rich. With the main jet in place, the engine may be revved above 3/4 throttle.

Because the slide needle is tapered, it will affect mixtures at all rpms, but has the least effect at idle and full throttle.

While a carb kit contains some nice parts, few contain the needle jet which wears at the same rate as the needle and both should be replace as a matched set. You can't buy a needle without a jet from Honda, but the aftermarket so called 'rebuild' kits will come with a new needle, but no needle jet.

Now while you say you cleaned the carb, did you remove the needle jet and clean it? Did you clean the air passage from the bell of the carb to the needle jet mixing chamber? To do so you need to remove the jet block (#7).

Now for the unschooled or novice carb mechanic; there are two o-rings on the jet block that become damaged from alcohol and age. The following pic is of a jet block with a failed lower o-ring and a damaged upper o-ring.

The hole between the o-rings allows air from the air passage in the mouth of the carb bell into the needle jet where fuel cavitation takes place so only fuel vapor and very fine droplets of fuel may get past the needle and enter the air stream passing under the slide on its way to the air control butterfly valve. Those o-rings are not replaceable, they come on the jet block. If the lower o-ring fails (common), fuel from the float bowl bypasses into the air passage and the result is an over rich mixture at all speeds. If the upper o-ring fails (not as common) air is drawn into the venturi lowering the vacuum and causing lean running at all speeds. A properly 'rebuilt' carburetor includes a new jet block or has the o-rings replaced by a specialty repair shop that purchases the o-rings from a custom o-ring supplier.

The following pic is a jet block that has been cleaned, has new o-rings and is ready to be installed.

Following pic is of the needle jet out of the jet block - notice in the previous pic a new needle jet and main jet are already in place. In this pic you see the result of years of alcohol blended fuel use and dirt that made it's way past the paper air filter or through the K&N filter.

In this pic you see a severely worn jet needle - although you don't see it, the needle jet was also worn more than doubling the amount of fuel mixed with the air. The engine ran like the choke was on all the time and it fouled plugs every time it it was ridden. They don't get much worse than this without causing engine damage. Note the clip will not stay on the needle as the groove is worn to the point that only the plastic washers on top and below the clip was keeping it in place.

In this pic you can see the wear and corrosion on the tip of the needle - the corrosion is the result of alcohol and water and the wear is from rattling around inside the needle jet while the engine is running near the top of it's rpm range. Thia carb was from a ETX that was used primarily for steady state cruising at both moderate speed (20 to 40 mph) and running down the road at full throttle (50 to 60 mph) for a mile or two before slowing down.

 

Yes I did replace everything and didn't check I will have to do this tonight I will let you know thanks for your help. I not take the plastic housing out because I broke the head off off one of the screws guess I am going to have to break out my machinist left handed drills and get that out. So before I jump off the bridge do you think it could be the cam??? Tried to find a mikuni oem rebuild kit with everything but the only number on the carb I can read is 42L018 and below that is KSY and the letter or number I can't read. It probably some polaris special number.

 

The e clip was at position three.

 

Those tamper proof torx screws are loctite'ed too - got the heat the carb to about 200 degrees - clip on 3 is the std position

 

This is why I think you’re one of the most valuable members on the forum Latebird. You didn’t flame me for being wrong or talk down to me, you taught me. I have a maximum of 5 or 6 years of reasonable experience with small engines and only about 3 or 4 of those years has been with success in getting things running right. I’m still learning a ton since I’m only 14 and I love reading through your longer posts that really go into why something is how it is.

 

Congratulations Scrappy and thanks. I had an advantage most people don't get. I grew up on a farm and my dad wanted his kids to better than 'farmers'. My oldest sister became an RN and my older brother (6 years older) graduated college before I was out of high school. He was trained as a journeyman mechanic. He started teaching me how to work on engines when I was 12. By the time I was 16 and he graduated college, I knew almost as much about engines as he did. In 1966 when I was 15, I was working part time in a Kawasaki shop. I could only work when I wasn't needed on the farm and my dad or brother had to take me to work as I didn't have a drivers license or a vehicle and it was too far to ride a bicycle. I got a degree in electronics, my younger sister graduated Cosmetology and my youngest sister got a job with a phone company in Yellow Pages Advertising right out of high school - she married a guy who ran an advertising agency in Atlanta Ga who had a contract with Coca Cola - guess who retired at age 35 and lives on a mountain top in Marietta Ga?

I worked on Kawasaki, Yamaha, Bridgestone, Ducati, Honda, Hodaka, Triumph, BSA, Harley, Indian, Zundapp, Rokon, Bultaco, Ossa, Moto Guzzi, Benelli, Vespa and probably other brands that I have forgotten about. I never had the chance, but I wanted to work on Henderson, Excelsior and Velocette too. I had a thirst for knowledge and while I do not have a photographic memory, I do have exceptional retention. I could remember every part I removed, it's orientation and how it installed in relation to mating parts. My brother taught me to mark parts that were not marked so I put them back exactly as they came out. While other mechanics laid things out to remember the assembly, I just put parts in a box and looked for the one I needed when I needed it.

A couple of brands that I forgot about was Yankee, American Eagle and Rockford - those were American Branded Yamahas, Kawasakis and Bridgestones.

In addition to all the common brands today, I also work on all the Chinese, Korean and Taiwan produced ATV's, scooters, mini-bikes and go-karts. I don't work on side by sides other than the ones under warranty that I am contracted to work on. I am an authorized warranty repair for Original Scooters, Chicago Scooter Company, Roketa, TaoTao, Coleman, Motovox, Monster Moto, Baja, Jonway, BMS, Kandi, Razor, LEV, Coolster and several other Asian manufacturers.

By age 21 I was a lab technician with General Electric, at 25 I was working as a store manager for Montgomery Ward and at 30 I opened my own business and am still doing that today.

I am 70 years old and will be closing up shop in the next 5 years. Until then, I'm sharing the knowledge I have with others and sometimes I get confused and describe something incorrectly. When that happens, I expect to be corrected. I am not perfect and make mistakes, but not frequently.

 

I have the same exact quad and had the same exact issue, it was the cam. Polaris had an issue with their cams going flat in the Magnums and I think another model that used the same one, can remember which model off hand. They didn’t address it until early 2000 something. I put an aftermarket cam in mine with the same specs and it’s ran great ever since. Also a one size bigger jet (55?) in the carb helps the power band, it’s been four years since I had mine fixed so I can’t remember the details. It only had about 600 miles on it though at the time.

 

Well it was the cam took it apart and the exhaust lobe was missing about a 1/4 of an inch. Replaced the cam and it runs awesome. Really couldn't see it was that bad until I took off the rockers.

 

Well it was the cam took it apart and the exhaust lobe was missing about a 1/4 of an inch. Replaced the cam and it runs awesome. Really couldn't see it was that bad until I took off the rockers.

No, you can't see it, but you can measure the rocker arm movement (valve lift) and find it without disassembly. I hope you installed new rocker arms too - if not you will be redoing the job soon.