I have a 05 Grizzly and have about 170 miles on it.I think I am having the gas boil in the carb.After riding for a while and stop to take a break and start back up riding it will not pull a hill it just spits and sputtersand has almost caused me to wreck a couple of times most recently with my 3 year old daughter on board.I have taken it to the dealership and they can't find anything wrong with it.They said it has all the heat upgrades and Yamaha fixed that problem.I covered the pipe with heat wrap.What else can I do to fix this problem.I am just about ready to sell this and get something else.I hate to because I really like the Grizz.

 

mine did the same thing the exhause pipe run near the carb so i rap with ex tape and that help

 

Mine only did this if riding especially slow for extended periods of time or if the radiator was clogged. When it happened in the field and there was no way to clean my radiator, I removed my side panels and bungeed them to the back rack. Wait about 10 minutes to let the machine cool down before continuing (I generally had an overheat indicator light at this point as well) then I'd generally be OK for the rest of the ride until I got back where I could clean the mud out of my radiator.

I've also heard of instances of vapor lock occuring when the fuel cap vent is plugged up (be sure the tube is not obstructed). I've also heard that (at least some model years) have a ball bearing in the gas cap which acts as a stopper if the machine is tipped over to prevent fuel from flowing out of the vent tube. Be sure this ball bearing is not stuck and blocking the vent in a normal riding situation. From what I understand there is a plate held in by 3 screws on the underside of the gas cap, this holds the ball bearing in.

Being that you have an '05 model, you should have all of the upgrades that Yamaha incorporated to address this problem with the older models (vented side panels and a heat shield under the gas tank). Some people have wrapped their exhaust pipe with a heat reducer tape too but it sounds like you already did that.

Finally you can try one of those special coolants (i.e. Engine Ice) that is supposed to lower the engine's operating temperature...

 

Hmm. Are you positive it's boiling gas? Boiling gas wouldn't only impact hill climbs. It would also struggle just to idle. Are you sure it's not something like a sticking choke or a clogged fuel tank vent tube?