Well here's the problem. A month ago I began having trouble with my vinson. It wouldn't rev up at all it would just spit and sputter. I completely disassembled the carb and soaked it in a parts washer for two days. All the jets were clear but there was some crap around the needle and in the diaphragm. All the screens in the petcock and fuel line are clean and I even drained the tank and put in fresh gas. I cleaned everything with carb cleaner and blew it out with compressed air. I replaced all the o-rings in the carb and put it all back together. I even put in a new spark plug and replaced the fuel line. Now it revs up but won't go wide open for some reason. It feels like it's running at 1/4 throttle. When I originally checked the spark plug it indicated that it was running very lean. Any suggestions would be appreciated.

 

Problem solved. The diaphragm wasn't seated very well. I also found more gunk in the bowl. It's amazing that you can clean a carb several times and still find crap in it.

 

Just a FYI, I run Seafoam fuel additive thru my quads twice a year to keep the carbs clean. Works really well

 

Seafoam is some great stuff.

 

I have a similar problem...I rebuilt the carb and it runs fine other than it won't rev out and only runs about 30MPH at full throttle. Just wondering which diaphram was causing your trouble? The one on the side of the carb or the one on the top of the carb? I presume it is the top one, which effects how far the slide opens (via vacuum).

2003 Vinson Auto

 

I'm having a similar problem. But I ran Seafoam through it, before it would only halfway run with choke partially on. But while I was trying to find a vacuum leak I held my hand over snorkel and found out if I partially blocked it the engine would run just fine, so I partially blocked it with a sponge applicator that you use apply wax with. Runs great but I still don't know what would cause the problem. I thought it might be the top diaphram Which diaphram was causing your trouble? I have not taken mine apart yet.

2004 Vinson Manual