My wife's 350 grizzly backfires when the throttle is closed.. any ideas why ? i changed the spark plug, cleaned & re-oiled the air filter media
but it still does it.. any help wold be appreciated..
I have also tried to adjust the carb on the left side of the ATV .. it does not seem to make any difference what so ever in the smoothness or speed of the engine..

tia

markinla

 

If I understand you correctly, when you jave it wound up and back off it backfires, right? alot af machines will do this, when you back off its still puttin gas and air into cyli9nder and when you touch the throttle agin it all ignites at once causing the backfire, its probably a little lean on the mixture, check the air -fuel srew on bottom of carb, probably a brass cap covering it , can be drilled, sheet-metal screw , inserted into it and removed, the pilot screw under it shpuld be set at 2.5 turns out, I've seen them completely shut from the factory, makes them cold blooded and cuses backfire

 

I'm having similar issues. MY machine leaks fuel out the overflow and backfires after it's been given throttle. Is this because of my air mixture screw because I know that its not adjusted properly.

 

Your float level is wrong if fuel comes out of the overflow, though I guess the back pressure of a blowback could cause it. Anyway, check the float needle, and float height if it is adjustable. Honda 450s backfire on the overrun so regularly that they blow the baffles out of the silencer, nothing wrong with the bike, they just do.

 

I have an 06 Yamaha bruin 350 how do i adjust the float height.

 

Im doing an oil change with https://www.canadiantire.ca/en/pdp/m...w.ds#store=194

And putting https://www.canadiantire.ca/en/pdp/m...-0280249p.html in my diffs for my Yamaha bruin 350 2006 is this stuff ok?

 

My Bruin manual is downright weird, gives full info for a YFM400 and "suplimentary" for the Bruin. Carb info is only for the 400 so does it cover Bruin as well?

Anyway, you put a clear plastic pipe onto the bottom of the float chamber instead of the drain pipe. Bend this pipe upwards and undo the drain screw on the float bowl. Fuel level should be 4mm to 5mm above the float chamber joint (seems high to me, I go for just below the join myself, if I am setting an unknown carb). If it is well wrong, you take the float out and bend the tang that the needle bumps against, then re-check fuel level.

Those links don't work with my browser so can't say on oil.

 

the oil is 10w40 motomaster atv/utv oil
And the diff oil is 80w90 motomaster extreme presure gear oil which is gl5

 

Both oils should be OK on a Bruin/350 Grizzly.

 

I adjusted my air mixture screw and it work better now, but it still lets out about half a liter of gasoline out through the overflow every night.
I have been trying to figure out how to adjust the float and the spec but I couldn't figure it out and couldn't find any tutorials.