QuestionI have a 1997 350 wolverine that has very little low end power. When first starting to accelerate it is very sluggish, but as the rpms come up it feels like a power band is kicking in (I know it doesn't have one) and it really takes off. As long as I'm going through the gears and the rpms are up the atv really runs well. It also idles well. I have just completed a thorough cleaning of the carburetor. While removing and cleaning all the jets, I only found one needle valve that was adjustable. This was also the one with the most varnish. After seeing all the varnish on this particular jet I really felt that cleaning it would solve my trouble - well it didn't. The atv does appear to idle better and run better on top end since the carburetor cleaning, but I still have little low end power - it will hardly pull my utility trailer. Concering the one adjustable jet - I have tried screwing it in - this causes the engine to pop; I have tried screwing it out - haven't noticed any difference in performance. Any ideas? I have read your 'Carburetor 101' article and that is what has helped get me this far. I greatly appreciate your help.
AnswerHi Shane,
I suspect the carburetor needs more thoroughly cleaned and tuned, respectfully.
The pilot circuit seems to be obstructed. Ensure that all fuel and air hoses are properly routed and not pinched.
The needle valve (float valve) is not adjustable. The float rides on the needle valve. The needle valve has a spring loaded pin or axle. Fuel varnishes (gums) inside the needle valve. Make sure the pin depresses and returns without resistance.
The pilot screw and idle screw are the parts that can be adjusted. You're probably turning the pilot screw. Prior to removal, remember to count how many turns in the screw is set so you can easily re-set it upon re-assembly. If necessary, set it to 2 turns out from lightly seated and tune accordingly from there. Tune the pilot screw in half turn increments.
Inspect the air-cut off diaphragm for defects. Avoid getting carb cleaner on the diaphragm.
Inspect the throttle slide diphragm. Avoid getting carb cleaner on the diaphragm.
Inspect the air filter and airbox. Clean both accordingly.
I cannot stress the importance of thoroughly cleaning each and every air and fuel passageway, and all removable parts. Every pinhole in the carburetor has an import function and must be unobstructed.
Along with compressed air and checmicals, use pipe cleaning brushes, small gun bore cleaning brushes, Q-Tips, tooth brushes, brass brushes, tool pick sets, guitar string, and other resources to help clean the carb boday and parts.
I return tech files such as (Carb Cleaning 101) by email. There was no email with your question as requested and explained in my instructions.
Try cleaning the carb more thoroughly. Check the entire fuel system for evidence of varnishing and other fuel contamination. Clean or reapir accordingly or the freshly cleaned carb will immediately be contaminated as fuel enters the float bowl.
Keep me posted on your progress, or lack thereof.
Respectfully,
Mark Shively
