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Xr250r 1993 starting /choke

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Ok been rebuilding my Xr250r nut and bolt job , engine has been fully rebuilt everything is new / reconditioned. When i bought the bike didnt start so no history on starting .

i have noticed the bike will not start if the choke is on even when stone cold . All jets all clean in the carb . Seals good etc.

set the mix to what manual states as 2 and a quarter turns .

bike starts cold no choke after a couple of kicks and when its warm first kick . Revs perfectly i havnt revved it like a mad man as it need bedding in yet

if i pull the choke up the bike cuts out and half choke doesnt seem to have any effect 

any imput would be great 

cheers steve 

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Sounds like it is a bit too rich at idle, I am guessing the air filter is clean ?  also check the float height. Maybe it may needs a leaner slow jet , when you changed the jets did you check if the new slow jet was the same size as the old one ?

Mine sometimes won't start on full choke, I give it a couple of kicks, put it down to half choke and she normally fire right up. but if I lift the choke right up when she is running she cuts out immediately even when cold,

If she starts & runs that easy there can't be too much wrong with it.

 

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Had a full rebuild kit just ordered off the vin , didnt check the sizing as standard spec sizes on the jets and pin . 

Thats the same as mine even stone cold

on start up if you lift choke bike dies half choke doesnt seem have any effect.

engine runs like a dream no smoke revs up clean does pop and bang abit on the deceleration . Dont no if its normal for these. Never had one before . The front wheels off the ground just off acceleration aswell seems abit of an animal even tho iv read these dont seem to have much grunt in them 

im just worried if its to rich will damage my engine the engine work alone cost me a grand , and total rebuild 3 grand ordering parks from all over the world , i think id cry if it went pop .

ill add some pics soon just couple bits still needed to finish 

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Also air filter brand new and the mesh insert part completely cleaned and clear

.

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Air cleaner over oiled? I've done that a few times

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Sounds rich it should need the choke to pull the fuel into the combustion chamber (unless its got a pumper carb) starting from cold. Have you checked the choke butterfly? the stock choke has a backfire plate spring loaded and the spring brakes causing the backfire plate to drop down when the choke is off although that wont stop it starting on choke. have you removed the air box snorkel?? also running rich can harm the engine. The excess fuel will wash the oil off the cylinder walls reducing lubrication not a good thing. also running lean can harm the engine burning valves and warping head, cylinder. you have to be out by a fair bit and run for some time to kill the donk granted its stock. the other thing is have you checked the air cut off diaphragm on the side of the carb it can cause rich mixture if not working properly. Carbys can be tricky if you don't understand them. do you have a workshop manual? would explain a lot. good luck with it and let us know how you went.....cheers

 

 

 

 

 

 

 

 

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Yer thats what im thinking to rich ; when the mixture screw is turned , what direction adds more air ? 

The carb is a standard type has pd on the side i did check the side diaphram and seems ok no splits and nice and strong . Im not sure on the choke flap it just seems to pivot on the arm that controls the movement dont recall a spring ?

when you refer to the snockle do you mean the pipe that links carb to airbox ?

the weather has been hot everytime iv tried to start the bike , might try the choke on the next cold day see if its needed . 

Im just worried to start using it if its running the wrong mix to do damage also is stock but the bore was oversized to 75mm

model is a 1993 250r 

hope this helps 

 

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The mixture screw (under the carb in front of the fuel bowel) adjusts the fuel on the idol circuit not air. If you screw it in then less fuel leaning out the mix. screw it out and you add more fuel to the mix making it richer. you can read the spark plug to see if your in the right paddock......a black plug indicates a rich fuel air mix.... a grey plug good.....a white plug too lean.      if you are uncomfortable doing this you can pay a professional how ever it is best to learn how to do it for your self. its good you checked the diaphragm although they can get pin holes that can only be seen if it is stretched slightly. the choke flap if stock has a half moon shape tin flap on the bottom choke on to see it. if it does not have the flap id say its prob an aftermarket. as for the snorkel it fits in the top of the air box under the seat not the carby boot. its a factory restrictor that pops out for more air flow into the air box.

hot or cold weather if the engine is cold then it should need choke. After sitting the fuel in the carb drops back to the bowel and or evaporates from the circuits the choke is needed to draw the fuel back up and into the engine (that's what its there for) the size of your piston does not make a huge difference being up sized it will allow slightly more air fuel mix into the combustion chamber making a bigger bang and more power. mostly its all about flow ie. more air fuel mix into the engine and ease of exhaust out = more power......a good workshop manual will explain the carby in detail and the adjustments needed. Or check out a jetting post on here the ones iv seen have pix of this stuff and might help with more explanation. good luck with it all I hope I have helped .

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Yes you help is great , i think my snorkel has been removed my airbox just has a square hole in thats under the seat , 

i will have another go at setting the carb i have a manual and states 2 and a quarter turns and heat up the engine set the idle then adjust mix screw to the highest rpm then reduce idel again .

when i turned in the screw engine died and didnt rev nice , so iv felt it arround 2 turns out from base , nice rev but again choke not needed to start , i turn the idle screw up and just kick and it fires up no problem and hot just kick once 

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hmmm well if its running good and the plugs not black id leave it. Theres nothing wrong with an easy to start bike. if theres a big hole in the top of the air box then yehh the snorkel has been removed. the manual is right though when you get the high rev drop it back just a bit. the high rev is the mix getting leaner. also the amount of turns on the mix screw is relative to the jet size. did you check out the jetting post? it explains a lot. good to be of help....cheers

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Dude that's an awesome lookin bit of kit I like it! bet youv spent some dosh on her though. nice one you have done a great job on the detailing sweeeet.

keep that beast thumpin!

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its not finished yet i have the front mudgaurd and the graphics to fit , yer been doing it over the year and set me back around 3 grand but everything is brand new , been a nightmare getting parts for it .  Its to good to ride thats the problem now lol . You cant see on the pics but all the engine cases and swing arm have been chromed 

looks the part 

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ha ha yehh that's the problem after spending that much and it looking that good it seems a shame to get mud and crud all over it! Im the same (although my bike is no where near that good) after the money spent and time taken I find my self dodging mud and puddles. guess wel just have to get over it! after all that's what the bikes were built for. great looking bike though you must be proud

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when it goes for the mot im thinking that i might just ask them to set the carb up ,then ill stop worring about it harming the engine with the richness . Ill remove the plug tonight and see the colour was brand new so hopefully got some signs of colour to see whats happening . 

Does your xr pop and bang on the deceleration? 

 

 

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it does not realy pop and bang so much maybe on hard engine braking I cant say I have payed a lot of attention  to it? next time I go out for a ride il take note of it

if you have the bucks for it get a professional to have a go best would be Honda theyd know better than any one and its piece of mind. if youv done some thing wrong then they should be able to tell you. that way you know for the future. itl probably cost a bit but nothing compared to a new donk.

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I think it just needs that final tweek as it fires up easy hot or cold but might aswell not have the choke as it does nothing . 

It seems very powerful aswell a couple of my mates have had them and was like you needed get the 400 250 really under powered . Doesnt seem it to me . 

I have had superbikes all my life so its not like iv come from a 50cc if you get me.

 

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yehh its all good. hey if its got the grunt and your happy then who cares what others think besides iv seen these 250s pop the front wheel up in 3rd gear no clutch on road so theyr not that gutless!  the 250r is what I wanted originaly but wen I went looking for one the 400s were cheeper so I got one of those instead. in the end im happy with the 400 it pulls like a dozer on steroids and no need to over rev although a 250 would probably be a better match being lighter im only 56 kg and 5.9 so the 400 is a touch heavy

hell of a lot of fun though:ride:

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