Ok need some help. I have a 1998 Suzuki LT250 atv. It recently started to have issues. It starts fine and idles great. The problem is when you attempt to give it gas it bogs down and will not gain any rpms. Kicker is that if you shut it off and restart it, it will rev up for a second or two and then starts to bog down again. I have drained the tank, replaced with new fuel, changed the spark plug and finally rebuilt the carburetor. It starts easily and idles great but still I can not rev the engine up. I pulled the fuel shut off valve and checked the vacuum line that goes to the carburetor, which seems to be clear. My question is does the diaphragm on the back side of the fuel shut off go bad? If so can I replace just the diaphragm or do I need to replace the whole valve assembly? If so where is a good place to get the parts?
Starting to get frustrated with this issue. I have owned the machine from day 1 and it has not given me any issues other than this. Any help is greatly appreciated.