I have a LTZ50 causing problems with rev, quad starts on first pull, runs full revs full speed for about 3-5mins then starts to rev up and down goes down to idle speed then flat out revs then back down etc etc.

I have done away with the parking brake with a switch to start I turn switch on then when its started turn it off to get the full revs this switch bypasses the parking brake safety mechanism.
checked timing all 100%, cleaned carb and float etc all good as it revs at start almost like it starts reviving up an down when it warms up.
I have a brand new battery in the quad also.
my next option is to put a new cdi box but want to know has any one come across and cured this problem before I throw money into a cdi box that wont cure the problem.

any help would be greatly appreciated thanks

 

im having thee same problem. i think my carb is the isssue. i ran seafoam through mine today the high reving idle and back down stuff went away from what i can recognize but im having black smoke and bog issues now. ive replaced my air filter re did fuel hoses got a yamaha petcock for it and plugged my diaphram line. changed oil changed oil filter threw a inline fuel filter new gas. im stumped right now. it might be the CDI thats what im also thinking about now as well. i think i need to take the carb and clean everything tho. i just really dont want to cuz its such a B to getmy carb out. i got a suzuki eiger 400 2003. im also going to be reinstalling my plug too. i have a thread if you want to go see all the stuff ive done to mine that hasnt really fixed it yet. btw i also have no parking break.

 

Was yours reving up full speed an down to idle from start or only when it warmed up.
Mine goes grand for 2mins at start an then starts doing it. I think I'm goin try a cdi box but they r expensive that's my problem wouldn't mind putting 1 in if knew it would cure it
Thanks

 

Air leaks?

 

taking my carb apart today. what it was doing witrh mine was in idle it would shoot up in IDLE to the point where i can to turn it off cuz idk what was going on lmfao. run some seafoam in it maybe your mid range jet is clogged? unless you wanna take your carb apart and check the jets.

 

I put a new carb kit in mine new jets etc.
I can't see it being air leaks on mine as it revs flat out when just started for like 2-3mins then starts goin up and down revs when u have the throttle on.
Then u turn it off and leave it couple mins an away it goes again no probs for min r 2 then it does it again.
Head fry has to be electrical as only does it when warmed up

 

ok heres my update, i dont have a carb kit but i did take my carb apart, MY MAIN JET WAS NOT EVEN IN. IT WAS JUST DANGLING AROUND INSIDE MY CARB. also my smallest jet was clogged, im almost certain this will fix my issue LOL. ill let you know later on just letting everything sock in carb cleaner. i never took my czrb apart i guess the last guy who had this was just a little brain dead.

 

hey haved you checked your throttle cable? it might not be screwed in properly thats what happened with mine!