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2troke powerband issue

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This topic contains 31 replies, has 0 voices, and was last updated by  Bruce Curtis 15 years ago.

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  • March 18, 2010 at 11:47 pm #98201

    hillsie
    Member

    hi all maybe someone can help with a small issue ive developed with my wr250z.the bike was running great on silkoline 2smoke oil then i think ive stuffed up grabbed some valvoline 2stroke racing oil from the servo for the new batch of fuel 350ml to 10l mix bike fan fine for a few hours but started getting eratic in its powerband. some times its a bit slow to hit some times seems to stick on. makes it a bit hard to judge when trying to jump somthing or blip over a rock. bike starts and runs fine. doesent seem to rev out quite as quik tho(seems to be doggier) which i put down to the oil. what im getting at is do u think its just down to the oil or should i check out the reeds(filters clean)or should i pull out the powervalve assembly and have a look(could be gummed up?)can these be removed whyle barrels on or should i whip the top end off and go from there my clymer manul onley shows it removed with the barrel on a bench. what do u think

    March 19, 2010 at 12:55 am #173690

    Dean
    Member

    Sounds like it could be your Power valve not opening up correctley,easy enough to check pull the cover off and watch its operation as you wind the revs on. Id say its a Tad rich on the oil ratio as well I work on 40:1 with semi synthetic and 50 :1 with full synthetic you should always try and use the same oil and ratio’s as this will affect the fuel /air ratio and jetting

    I would also check your exhaust system,if it is all spooged up with gunk its not going to rev out properly. Bruce would be the best to ask with regard to the power valve removal. let us know how you go!

    Ollie

    March 19, 2010 at 1:13 am #173691

    mike
    Member

    I could be a cracked reed valve aswell. It happened to me once on a ride and my bike was running weird as a result. I started muckin around with the mixture screw thinkin it was that and stuffed it up and then kept doing plugs.I ended up takin it to the bike shop and they picked up the problem so I’d have a quick look at that aswell mate. Nice and easy to check but i had overlooked it.

    March 19, 2010 at 1:31 am #173692

    russell culley
    Member

    youre using almost double the oil that i use…as ollie says 50;1 or 200ml for 10 litres….by using more oil you are leaning out the fuel air ratio (the same volume of pre mix goes in but there is less petrol in it cos there is more oil) …you camn also try some REDEX in the fuel before you pull it down as this does a great job of ungumming a 2 smoke…then get an iridium plug…..but first go to 40 or 50 to 1 mix and give the engine a chance to burn it…hope you go ok B) B)

    March 19, 2010 at 1:44 am #173703

    Mick D
    Member

    35:1 does sound like a bit too much oil to me as well. I run our KX85 and 65 at 32:1 as per manufacturers recommendations. 250ml to 8ltrs. If the kids are not on the pipe, even at that mixture the bike will “splooge” a bit and not burn all the oil, which in turn oils up the pipe..

    March 19, 2010 at 3:50 am #173693

    hillsie
    Member

    righto ill whip the reeds out and have a sticky i thought the ratios were a bit of overkill as my old it and rmx ran 110mls to 5l but that was the old super tt oil. the guy i brought it off was running thas mix with synthetic the pipe hasent gone oily so i didnt realy clue him ill drain this lot and make a new batch what oil do u guys recomend ror it

    March 19, 2010 at 3:54 am #173712

    Anonymous

    My KTM 200 didn’t like it when I ran it at 40:1 which is what others with the same bike appear to run theirs at. Back at 50:1 it was noticeably better though.

    March 19, 2010 at 3:55 am #173694

    hillsie
    Member

    oh yeah and it already has an iridium plug in it and bought a spare this morning not sure what u mean by redex is it some kind of fuel system cleaner?

    March 19, 2010 at 4:08 am #173714

    Anonymous

    Yes it’s exactly that :-)

    March 19, 2010 at 7:04 am #173717

    dennis da menace
    Member

    yes, mixture. 350ml in 10L is about 28.57:1…

    way too oily, i reckon 40:1.

    but believe it or not i reckon bruce will disagree with us all as ive had this convo with him. he likes spoodge :laugh: :laugh:

    if you put race oil in it at that mix it may well have gunked up the powervalve and made it erratic.

    March 19, 2010 at 7:07 am #173745

    glenn
    Member

    Edited as this is in the tech help section Boony (again) remember the only sensible thread we have

    March 19, 2010 at 8:11 am #173695

    hillsie
    Member

    well had a look at the reeds no dramas then thought id cheat a bit had half a tank in her(4l) put 1 liter of straight fuel in and went for a squirt whoa diddnt that wake the old girl up not sure if the valves still sticking but awesome 4th gear clutch kick wheelie for a block so shes back to her old self but will have to tune it a bit as it wont idle but im pretty confident that was the issue will grab some fuel sys cleaner tomorrow and hopefully will make it better. now how to get the oil outa the pipe an oxie worked on the old it 175 pipe but dont think i can be that cruel to thiss one thanks for the help old bulls im still interested whether i can pull the power valve out to clean it tho. i will go for a more dedicated ride tmorrow arvo tho and see how it goes

    March 19, 2010 at 8:11 am #173713

    Dean
    Member

    bns454 wrote:

    Quote:
    what oil do u guys recomend ror it

    Any name brand semi synthetic or full synthetic oil will do some of these would be

    Castrol TTS
    Motul 800
    Mobil synthetic
    Penrite Synthetic
    Caltex Revtec (what I use at 40:1) or 250ml /10 litres

    I like the Caltex oil and have got good service out of all my 2 strokes using this.

    ollie

    March 19, 2010 at 8:51 am #173760

    alan
    Member

    that caltex oil is super cheap if you get it from the caltex depo its going in the kids bikes next wippersnipper lawnmower etc think its semi sinthetic and smells good

    March 19, 2010 at 9:01 am #173766

    Dean
    Member

    It sure is rocket I get it from the Woolworth servo so when you give them your 4c shopper docket and buy the Revtec (it might be called something else now) you get 8c a litre of your fuel. I think its only about $12 a litre B)

    Ollie

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