ATV Florida Forum

need help with grizzly 660 wont reach top speeds

you put too big of tires on it. lol. j/k. i dont know? take it to yamaha. thats what we do.

Can you be a litte more specific?

You have a bad wiffle valve , I suggest getting a can of compression.

Did you check for melvis diumprus in your carb?


Sound's like dust weevils to me.

How many times has it been sunk?  I dont mean to assume, but there are those that believe injesting muddy water into your motor and CVT transmission wont do any damage.
  You probably dont have any compression if the above has happened.  If the motor is reving but you arent getting any MPH then your CVT needs to be taken apart and serviced.

the bike has 300 hours on and has never been sunk in the mud, was hitting 68,69 mph but now only goes 65 hung out

Have you cleaned the air filter?  Or upgraded your air filter for more intake?

bigger tires would do that. more stuff on it like big cargo boxes and stuff would too. and the terrain you are on will do that. also if you are judging by the factory speedo it is wrong anyway. they go by engine rpm and not how fast the wheels are spinning. our rancher goes bout 40 to 50 depending on all of the above. we never worried bout it. 3 mph aint that big of a deal is it?

its not really the mph its the power i can feel the loss its been into yam 4 times they did a jet kit but it didn't really help i can be going 35 or so and hit it and it will go about 45 then bogs down pops and farts sometimes will almost die out i pump the gas up down a few times and it comes back it just seems like i don't get full power out of it this bike is stock been babyed it has 589's but they are stock size no bags or big racks

SD do you have a snorkel???  Its sounding like either your not getting enough fuel or air.  Also just for S-n-G's have you tried checking your spark plug boot and changing your spark plug?

Freakk

yeah freak put a new plug in and wire is good, use to just get up to speed no problem but seems now i have to go about a mile or so to get it up to speed

I'm in agreement w/ freak it sounds like it's not getting enough fuel or air.  I had a similar prob on my quad before the jet kit was put on it and it was tuned.  It may just need tome adjustment of the carburator.  Any info on the air filter?

Does the engine sound any different?  The other thing you might want to check is your exhaust pipe, it might be plugged. 

At what point did it start running bad? Did it ever run right after they messed with the jetting?

Similar thing happened to my old Grizzly..I actually blew the seam on the Muffler....start it up and see if you can feel air coming out the top of the pipe...??..maybe pull the jets and clean them...