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need help with yz250

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hi, iv got a 95 yz250 and having problems with it. dont know the bikes history but heres the prob. when i kick it over its realy hard to start and shoots a big rush of air out the end can(sounds like a gunshot) 20-30 kicks later it will start. it will tick over fine n rev but when riding theres no power band its compleatly flat where the band should kick in. also i noticed oil drippin out of end can, i know this is normal with 2T but its a lot of oil. i mix 150ml of oil to 5 litre petrol.

hope somone can shed some light on this.

thanks

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hi, iv got a 95 yz250 and having problems with it. dont know the bikes history but heres the prob. when i kick it over its realy hard to start and shoots a big rush of air out the end can(sounds like a gunshot) 20-30 kicks later it will start. it will tick over fine n rev but when riding theres no power band its compleatly flat where the band should kick in. also i noticed oil drippin out of end can, i know this is normal with 2T but its a lot of oil. i mix 150ml of oil to 5 litre petrol.

hope somone can shed some light on this.

thanks

think if it was me i would first pull the carb apart and check jetting to see there clear and keep the numbers off of them and check to see if there close to factory to start with and go from there, maybe check compression, the silencer could be stopped up. those would be the first to do on the list.

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150 to 5litre makes it about 33 to 1 and for that ratio you could run it pretty hard. I get it that you don't own the bike for long so the the obvious points are about topend and packing of the silencer? Take off the pipe and have a look into the cylinder. Mostlikely you need a new piston maybe even a replate of the cyclinder, after all its a bike from 95. Clutch also has a big impact on the bikes performance.

So you might be best off to get a manual for the bike or if you have it leave through a few times. Then pull the pipe and so on. If everthing is new anyway cleaning the carb seems like a good idea :smirk:

Edited by arnego2

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thanks guys. i will have a look in the exhaust, also will look at jets.i have cleaned the carb no end of times still no joy it dosent splutter just no band. i only weigh 60kg so maby its a good thing! also seems to be a steel ring aroud the outside of flywheel, im wondering weather this is a flywheel weight to smooth out the band?? looks like it can be taken off. big dent in expantion chamber aswell.

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If theres that much spooge id def check the jetting like stated above. Then pull the exhaust and clean it out, repack the silencer, and clean the powervalve. Id never cleaned the pv but once i got a manual i decided to try it on my 91 yz and i was easier than i thought. $30 for gaskets, o-rings and oil seal and parts cleaner and what a difference that made. Really snaps into the band now. Good luck, lots of help on here if you get stuck.

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ok thanks, just found out the powervalve linkage thing wasnt attached to the powervalve itself so sorted that. it starts up 1st kick with easy start then cuts out once it uses it all. maby some jets are blocked up gunna have anotha look, defo fuel problem now.

ok thanks, just found out the powervalve linkage thing wasnt attached to the powervalve itself so sorted that. it starts up 1st kick with easy start then cuts out once it uses it all. maby some jets are blocked up gunna have anotha look, defo fuel problem now.

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