This is part 2 or 3 of the same topic for me. When you load the engine for long periods of time, like going down the road at top speed in 5th gear, it starts to miss and pop. It'll do it on a long hill as well. I had it back to the dealer last year and they said everything is fine. I checked all the connections to the coil and the plug wire....seems OK. I looked up the jet sizes and stock is 150.....gonna bring a 145 out with me today to see if that works. Any similar stories with fixes, guys?

 

WOT will cause a miss due to the rev limiter wont it?

 

It ain't rev limiter.....I've had a dozen quads over the years and this problem is wierd! I phoned a couple of different dealerships today before I left ..........one guy has had a couple of machines in with the same symptoms......he thinks it's vapour locking. Says to put heat tape around the fuel lines and on the bottom of the tank. The symptoms fit. My machine ran flawless today....but the weather was only a few degrees above freezing today.

 

Ok well i guess check the easy stuff... Plug gap, float level in carb (i found mine way out, like 3~4mm after beating er on the trail) might be time for a carb cleaning to rule it out. Check the tank vent hose? Ive never heard of a cat needing heat tape yet.

 

I went through your list this aft Vewdew, new plug, carb clean, floats OK, clean air filter (wasn't bad). I left tank off, gonna run to Crappy Tire and get some heat tape anyways.......run it around the fuel line and put on bottom of tank. I also took two disks out of my Supertrapp.....only 6 in there now.

 

What altitude are you at? I am at 3500 ft. and had to jet my 400 auto down from a 150 to a 145 and put the fuel screw at 1 turn out and that cured the missing and surging problems at WOT. Try it.

 

Where I ride is over 4000 feet. Thanks for the tip......I thought that too, but THREE separate dealers said, "oh no, we've never had to jet these things down"........I'll order the jet today.

 

sno314 is using the same set up that I send out with all my new 400 A/C. The 145 main cured the surging at WOT and 1 turn out on the fuel screw make the low end more snappy. I am a dealer in Montana if you have any more ?'s call 406-543-5706 and we can help you out.

 

Cant get a better deal than that... Thx minimotor.... DaveB I was at crappy the other day and didnt see any tape, you got a product name?

 

I found two sourse of tape at Cambodian Rubber.......exhaust muffler fixer tape and autobody repair tape. Hahahahaha! Its all the same shat.....stickey metal tape.

Thanks for the confirmation Minimotor.....wish I had a dealer like you near me! The main jet has been changed to a 145 and the fuel screw is at 1.5 turns out (was 2.5 turns out from the factory). Heat tape is on fuel line and bottom of tank......now I need to go for a ride!