My 98 454 has great cold starts, idles rough after a few minutes then stalls if you are not on throttle, then won't start until it cools down. Carb float stuck open just recently when I forgot to shut off gas line and drained 2 gals of gas on floor. Took carb off, cleaned it, checked float, replaced choke cable but not spring and terminal end inside carb.. Plug gets black after a few minutes of idling. Once past 1/8 throttle it runs great. Have tried adjusting pilot screw but doesn't help.

 

I bought a used "96" 454 last spring and am having a blast on it. I too have experienced some starting/idle problems. I'm thinking the choke is super sensitive. Mine starts great no choke but after warming up just a bit needs 1/2 choke or so for a spell till full warm up. Can be very hard to start after a short run and shutting off. I manage to get mine running by trying different choke settings.

 

Thanks, mine has 7200 miles! Years ago I had problems with back firing every time I backed off from full throttle, didn't need to choke it either to start. I had it rejetted and tinkered with, no back fire since. This was many years ago. Also need choke to start now. This quad has been to hell and back many times. It's just a tank!

 

I have the same problem and had to remove and clean the carb and jets. If I don't plan on using the bike for a few days I have to shut the fuel off or it drains out. Have extra plugs available for when this happens and run some cleaner additves in the gas through the bike occasionally. Adjust the carb immediately after a cold start and you will notice a lot of the choke work will be diminished .

 

On to new discoveries. My 96 4 x 4 454 got to where it would only run for 1 minute and then sputter out. Under the sleeve for the float is a fuel filter. Had to remove float. A small screw holds the sleeve in. Then you can pull the sleeve. Mine was clogged with some kind of whitish gunk. Blew it off and out. Sprayed with some ether to flush. Reassembled and I'm screaming up and down my paths again. Seems to have solved the problem.