Lately its been acting sluggish.

Cleaned the air fliter well and took it for a test run down the street.

At first it sped up to what I expected and then about 100 yards down

it started to bog. Then I could only get it to go if I only pushed the throttle like 25%.

Anymore than that and it would act like it wanted to die.

After I turned around and got it back, I put the rear up on a block of wood.

I throttled it and of course it sped up to like 30-35 as fast as I would expect if nothing were wrong.

Any suggestions as to why it doing this?

 

Sir,
Taking stabs at it. Since it ran fine on blocks...there is no strain on the engine and no weight to pull. I would start off with a new plug, clean the carb really well blowing everything out and take a peak at the intake manifold and see if there is a leak or tear. Sometimes, it runs fine with no strain, then when you put weight on it, it leaks through. Also, if you have had it in water lately, ensure residual water is not on any vital areas. Lets start there and see what happens. Others will chime in the deeper you get into it. Good luck and Happy New Year. SEADAWG

 

OK I changed the plug, it was black with buildup and pulled the carb out, took it apart and blew it out and wiped it down (outside was filthy with sand and gunk) and then put it back together,

It fired right up and I let it run on blocks for 2 or so minutes. It acted well so I jumped on it and rode it down the street.

Noticed that you can only press in the throttle like 10-15% or it bogs bad ---BUT--- it did slowly make it up to top speed with me (300 lbs) on it.

So turned the bike around at the end of the street and rode back - same thing - had to really watch pressing in the throttle too much to keep it from

bogging but it did speed up to like 25 by the end of the street back to my house.

SO my question is now - would changing a jet help speed up the lower end any?

Or is it the quad is a 50 and should be slow anyway.

See we mostly ride in sand so it really slows down the quad. If he rode hardpack it probably would be fine.

 

I've never really dealt with quads before now, but have my share of experience jetting and tuning motorcycles.

That being said,

What you're describing about too much throttle bogging down the bike (usually followed by a surging when letting off throttle?) sounds like the bike is running rich. A Rich bike will bog down, then when the throttle is released will surge, or accellerate for a moment, becuase the fuel flow has slowed down and the engine can catch up finally. A lean bike will also act slow at first, then suddenly begin to pick up speed as you transition into the next stages of the carb.

Now, you don't neccessarily have to rejet if the bike is running rich, the most simple cause of this on a bike that used to run fine and has had no changes is a blocked air filter or something restricting airflow. For a lean bike, the airway could have cracked and is letting in too much air. Inspect for obvious cracks, and seal them temporarily (duct tape!) and ride it for a test. If that's it, replace the airway, or layer on some more duct tape.

A quick test for rich would be to remove the filter after the bike is warm and quickly run down the street. Don't go far, b/c if the bike is lean, you could do damage by runnnig the engine hot for too long. A quick spin should be okay.

Did the performance increase or get worse? If it got worse, you're running lean. If it got better, you were running too rich.

If you're running rich: Either the filter is clogged, the airway is clogged, or the mix has gotten way off. Inspect the airway, then if it's clear replace the filter. I usually run Permament filters like K&N or UNI since they can be cleaned and re-installed. If neither of those works, you are going to have to do some carb work and tune down the bike. Start with a leaner air/fuel mix, and if needed after that try a smaller pilot jet, then when the low end is satisfactory, adjust hte needle and main jets until all aspects of the powerband respond well.

If you're running lean: Increase the air/fuel mix. anything after about 2.5 turns is unmetered and will require jetting to solve. Try a bigger pilot jet, then raising hte needle and a bigger main jet as needed until all powerbands respond well.

I've got a good "How To" about carb jetting on my website:


Carb Jetting Basics

 

thanks I'll try it tonight (air filter manipulation) and then let you know what happens.

I'm thinking too rich but we'll see.

I definately want to replace the crappy air box with something better.