A lot of these guys don't get it with statements like "I ride very hard" that DOES NOT mean you WORK your quad very hard. I haven't witnessed grizzlies boiling gas but it's probably not too hard to do when going slow, Gee proper running tempereture for a water cooled engine is around 190 degrees, that tempereture radiating into the gas tank would eventually get gas to a rolling boil ( it boils at a far lower tempereture than water.) Secondarily you can vapor lock most any carbed engine that doesn't have lengthy intake headers, this doesn't suprize me either.

 

You know it amazes me what people expect from their quads. A buddy of mine has a 450es and took it to his fathers farm near Rome New York. Over the weekend he decided to hook his quad to a double bottom plow and begin plowing a twenty acre field after about three hours of dragging this plow up and down the field in ninety degree weather the engine locked up. All this dim witt could say was Honda builds junk. To Honda,s credit, I was amazed after about an hour of sitting it refired and ran fine Ding Dong finished plowing the field.

 

Andy,
yes, I've seen it yesterday.58degrees,very slow/muddy,lock 4wd often/ trailriding in the woods,around 8 miles into the trail my Grizz 660 26" Mudrunners,started sputtering and died within 10 minutes. I heard the gas boiling and it was still boiling 10 minutes later.I took off a side panel,waited 15 minutes and continued riding with no problem.
Joe

 

I saw it yesterday! This was my first long ride (bought the machine last Wed, tore a CV boot Thurs, Got it back Monday, (110 bucks later) went for a ride Yesterday and about 2 hours in, the machine stopped climbing hills. All it would do is sputter! Soon it wouldn't go if I gave it more than 1/2 throttle. We stopped to see if the plug was wet or something, and smelled alot of gas. I pulled out the vent tube and there was a TON of vapour shooting out! I opened the gas cap and watched the gas literally boil for 10 minutes! I went to the dealer today, and apparently Yamaha knows about the problem, and has set up some sort of kit to fix it (a reflector or something) I'll let you know. The dealer was/is great. If any of you guys want to buy in Ontario, let me know and I'll give you the Name & Number!

 

It seems to me like it is happening at low speeds, when there isn't enough air moving to cool the motor. It's like a muscle car sitting in traffic, the thing overheats, unless you are moving swiftly. You were moving slowly across a field, not enough air to cool it. But I still think they should design it to where it won't boil, that it should overheat before it boils. Best solution, keep moving at a steady pace!!!