Help with YZF

[dave hamilton]

just tried to start my bike after 8months since my accident and stuck fresh 91 fuel in and tried to kick it in to life but all i got was a couple of backfires what would cause this any suggestions would be helpful as the bike was going great before my crash and made me unable to ride for 8months

[Pornstar]

Stale fuel in the carb? give it a drainin.

[D3ALN]

yup have to agree with above. I dropped my oil and oil filter after leaving my bike sitting for a month.

[YellowDog]

Take it to the top of a long hill and bump start in 3rd gear.

The carb will clear and the new stuff will flow through and start the bike

[CRF119]

Pretty much what they have said.

Sitting for 8 months i would:

New Air Filter
Oil Filter
Oil
Drain carb

While you are at it cheek your plug.

BTW ive never seen a YZF run well on 91 possibly be nicer to it and put it in some good stuff

[dave hamilton]

yep done the new filter.oil. will get a new plug and get sum 98 in her thanks for the help guys

[Jonny Rotten]

run it on 96....my yzf will only run on 96 and will cough and backfire if i put 91 in it.

[D3ALN]

running my wr on 50 50 mix of av gas and 91 gives me smoother acceleration and dosnt stall when idling slowly across rivers anymore.

[K6K]

running my wr on 50 50 mix of av gas and 91 gives me smoother acceleration and dosnt stall when idling slowly across rivers anymore.

mixing av gas and 91 @ 50/50 is going to give you an octane of around 95/98. It cant be cheaper to use the mix over normal premium? The av gas maybe burning a bit cleaner but you usually don't need jetting changes for higher octane. All it does is resist knock better, and a WR shouldn't knock using 95 and you can possibly get away with 91.

The YZ has a higher compression piston and does need 95+

[green machine]

running my wr on 50 50 mix of av gas and 91 gives me smoother acceleration and dosnt stall when idling slowly across rivers anymore.

Is the av gas your running unleaded?,mate had problems with his KXF not running properly(overheating,erratic idle),as soon as we told Scott from MR's that the exhaust pipe was really white he asked "you running av gas?" yep 50/50 av gas 91,said my mate,Scott told his ditch the av gas and run 95 or 98,modern four strokes don't like leaded fuel.Mate put 98 in bike's run sweet ever since............

[D3ALN]

my exhaust goes a little white. Andhave had no problems everyone i ride with does the same. Wr450 x2, yzf450 x 2, yz250f x 3,wr250 x2, kawasaki quad.

[green machine]

my exhaust goes a little white. Andhave had no problems everyone i ride with does the same. Wr450 x2, yzf450 x 2, yz250f x 3,wr250 x2, kawasaki quad.

Is it leaded av gas tho?,what advantage is there running av gas/91 as opposed
to 98 premium?,can't be price cause av gas aint cheap,and the power gains would be minimal, i run 98 and after what Scott told me i just wouldn't risk it.......if he sees this thread he might chip in.....edit,i just read your earlier post,would 98 achieve the same results?,have you tried it?

[K6K]

Is it leaded av gas tho?,what advantage is there running av gas/91 as opposed
to 98 premium?,can't be price cause av gas aint cheap,and the power gains would be minimal, i run 98 and after what Scott told me i just wouldn't risk it.......if he sees this thread he might chip in.....edit,i just read your earlier post,would 98 achieve the same results?,have you tried it?

power gains would be zero unless you bump up the compression (use a YZ 13.5:1 piston as opposed to the 12.5:1 WR piston for example) to use the superior knock resistance of the higher octane.