so heres the deal. i got this quad with no exhaust and a k&n filter mounted directly to the carb. got an exhaust-stock pipe to older dg muffler. it starts but wont idle without the choke on, and then it idles high. give it gas and it bogs and stumble and will die. if you blip the throttle a bunch of times rapidly it will eventually hit high rpm's and it runs fine at higher rpm. ive cleaned the carbm adjusted the float, tried adjusting the pilot screw, nothing works, im ready to throw this damn thing in the river. any ideas???

 

Well i have had a really tuff time with mine, its an 85. Figured it out, it was my tranny oil leaking into the jug and burning. The oil in your tranny has a much higher viscosity and will make it bog, not idle, and really hard to start. Also fouls plug after plug. Drain it and put some new in. Should be about 900ML. You drain it from the bttom of the engine. Big plug can't miss, dead center. Mine was very thin and gassy, a bad sign. Put new in and try to get it going. If it is really smokey, thats your problem, otherwise run it and make sure the level doesn't go down. Try that and let me know how it goes, these are great machines, just old. If it does smoke btw its your crank seal on the wet side where your clutch is and all. Make sure you are also not burning coolant!

 

mine actually dosnt smoke, barely a puff at start up or when i rev it high. im pretty sure its the carb, ordered a rebuild kit, when i hose that carb with starting fluid while its running it seems to calm it down some, i think the o rings are leaking. and i dont know about yours but mine is aircooled?=no coolant?

 

I guess the 89 is air cooled, huh. Well than no coolant problems. Still for the sake of your clutch check to see if there is any gear oil anyways, it needs to be replaced at least once a year. It could be empty even, it was on mine practically. Ya carbs are finiky make sure the adjustments at at the stock position. There are two of them on the mukuni carb. 32:1 using synthetic? Check your plug. What color?

 

plug looks slightly rich, using regular 10-40 oil. no premix in this, just straight gas and striaght oil. as far as i know the clutch gets its oil from the motor oil? dont see a seperate drain/fill, looks like its all motor oil to me? ordered a carb rebuild kit, well see if that helps, gonna recheck the timing and a few other things too. it seems to vibrate a bit more then normal so im gonna check all the bolts and so on too.

 

I've had a similar issue working on my 89 quadsport. Bike ran at a really high rpm at idle, and ran better with the choke on, pilot screw did nothing. I rebuilt that carb and had the same thing happen after. In the end I swapped out the carb to a spare I had and it fixed the problem- haven't looked at the old carb yet, but there was defiantly something wrong with it.
Other possibilities are it's jetted way lean, or a intake air leak.

 

decided it was too lean. ordered a rebuild kit so i figured drilling out the old pilot jet couldnt hurt, ive got a new set in the mail...ill be dammed if it dosnt run like a raped ape now! drilled out the jet with the smallest drillbit i had, which was probably 3x the original size. got it fired up with no choke, set the pilot screw about 3/4 of a turn out and it runs absolutly perfect! plug color is right in the middle, quad screams, runs amazing, couldnt ask for it to be better. while i had it all apart i took a length of hose from an old pool filter, a rubber coupler, and the air filter and extended the filter mount to the rear seat. rubber coupler on the carb to the hose, hose runs under the frame to the battery box area, filter mounted to hose. looks slick and works great. found the source of my vibration as well, missing upper motor mount. adjusted the valves, camshaft and all internals are in perfect shape, all newer looking parts, motor has been bored out some, couldnt tell how much but i could see that it wasnt a stock piston. just need to get the plastics painted, new seat and bleed the damn brakes and its fun time!!

 

Valves? It's a 2 stroke right?

 

pretty sure its a 4 stroke

 

It definatly would be a 4 stroke.