86 LT230 quadrunner getting to much air

[tjakes680]

So this morning i start quad it starts right up idles excellant i cahnged air filter old one was dry put freshly cleaned and oiled one still the same I pulled fuel line to carb at idle up to 3/4 throtle fuel is flowing the diameter of supply line but at 3/4 to full throtle it gets less deffintly a noticable diffrence less im going to change fuel pump and hopefully this is it I have brans new fuel pump OEM never used so ill give it a shot if thats not it i dont know what or wjere it could be ill report back what the outcome is later today Fingers crossed Mech lol and toes 

[Mech]

Onya. The vacuum drops off when the motor's under a load.. Hopefully that's the problem and it is just the pump. Otherwise... you've got low vacuum.

Low vacuum could be valve clearance, blocked exhaust, worn motor. Low vacuum at revs is a sign of a blocked exhaust. Low vacuum at low or all revs would be the others.

In some of the manuals they say to take a bung out of the back of the muffler and drain the muffler.. I've never found anything at all in there, but they seem to think they block up if they spend a lot of time going slow.. Presumably some sort of oily gunk.

[tjakes680]

1 hour ago, Mech said:

Onya. The vacuum drops off when the motor's under a load.. Hopefully that's the problem and it is just the pump. Otherwise... you've got low vacuum.

Low vacuum could be valve clearance, blocked exhaust, worn motor. Low vacuum at revs is a sign of a blocked exhaust. Low vacuum at low or all revs would be the others.

In some of the manuals they say to take a bung out of the back of the muffler and drain the muffler.. I've never found anything at all in there, but they seem to think they block up if they spend a lot of time going slow.. Presumably some sort of oily gunk.

Well today is the day if its possible ready for this i change the pump i take it for a ride and its running great up to 3/4 throtle i look at thumb throtle its past handle bar grip starts bogging I go and chk throtle stop screw its loose !! I set it to be even with handle bar grip meaning full throtle thumb lever is even to hand grip I chk all my other quads there all set the same. Now all of the sudden the carb is adjusting everythings working i download speedomoter app bike doing 48-51 mph at full throtle 5 th gear with it allways did no hesitation no backfiring no bogg !!! What I think happened was with all the vibration of the high idle s for days and taking the throtle cable on and off somehow the throtle stop got loose so i was going full throtle and actually pulling past the max ht of slide basically going into negitve air if that s what its called , and the way its set now the fuel does not break up going to carb at full throtle before it was again prob not enough vacumn because throtle was going past full open So now its tight set i checked side its going all the way up and quads running better then ever only took 3 rebuilt carbs 2 fuel pumps and all new air ducts and of course a manifold I basically revuilt the entire air and fuel system because a throtle stop was loose lol  I cant think of anything else that it could have been like i been saying it idles perfect but once open to what i thought was full it would bog so it was going past full throtle Mech thanks for all ur help it was invaluable you really helped me out !!!!!!!!!! So im going to mark this one SOLVED!!!!!!!!!!!!

[Mech]

Ok. Well I'm glad it's going good again. And you've checked(by taking the inlet piping off and feeling with a finger) that the slide is going up far enough so it's not intruding into the venturi at all ?

Every carby I've seen the slide hit the cap on top, and that was just full open venturi. If you check and find the slide's not opening the venturi fully, then the problem will be that the slide needle's the wrong one or set wrong.

Then again, perhaps suzuki decided the slide had to stay a little way down to maintain a little vacuum for the pump to operate. I've never played with one of those carbys on a bike with a pump. All our quads here have diaphragm carbies.

I guess after all this you'll be happy just to leave well alone, and I couldn't fault that.  But then.. perhaps it can go just a tiny bit faster.. Me though, I don't think I've ever been fifty miles an hour on a friggen quad..  That's nutty.

haha.  Have fun.. but don't get caught.

[tjakes680]

7 minutes ago, Mech said:

Ok. Well I'm glad it's going good again. And you've checked(by taking the inlet piping off and feeling with a finger) that the slide is going up far enough so it's not intruding into the venturi at all ?

Every carby I've seen the slide hit the cap on top, and that was just full open venturi. If you check and find the slide's not opening the venturi fully, then the problem will be that the slide needle's the wrong one or set wrong.

Then again, perhaps suzuki decided the slide had to stay a little way down to maintain a little vacuum for the pump to operate. I've never played with one of those carbys on a bike with a pump. All our quads here have diaphragm carbies.

I guess after all this you'll be happy just to leave well alone, and I couldn't fault that.  But then.. perhaps it can go just a tiny bit faster.. Me though, I don't think I've ever been fifty miles an hour on a friggen quad..  That's nutty.

haha.  Have fun.. but don't get caught.

Its top speed is 51 in 5th gear Im almost positve this was the problem because now at full throtle i get steddy pipe diameter fuel flow if i move stop screw to open throtle more it breaks up and spurts and thats exactly how the quad runs like farts lol So im assuming the vacume is just not able to maintain a stedy flow past that point Hey I look at this way now i have 3 OEM carbs rebuilt and know the fuel and air system of this quad inside out upside down Nothing like on the job training thanks again im going go out with it in a day or so and take it in trails and run it but it ran for a few hours today without a hitch Thanks again my friend 

Edited February 14, 2022 by tjakes680

[Mech]

My pleasure..  Ride safe.