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Discussion Starter · #1 ·
Hi every one.
I have a 250x and i spent the last month rebuilding it and now that i have it running it smokes.:sad:
This is what i have put into it: Wiseco piston, new jug, new head all new parts, It has a brand new cam but i used the old cam chain because it looked good. I prelubed every thing with baring oil. I adjusted the valves to spec and timed it.
I cleaned the carb but it would not start unless i puled it with another atv and then it ran really ruff and smoked a lot
Smoked white well idling and a tinge of blue off ideal and then puked out black smoke at three quarters throttle to WOT. It would bog down and run reel rough at WOT.
So i took the carb back off and gave it a reel good cleaning and after that I got it to start with the kick start with a little throttle.
It was able to idle around 1700 rpms but would die if lowed any.

I ran it around the back yard for five minuets or so was really rough and at idel it would serg.
A lot of the smoking cleared up after riding it for the five minuets but still smokes black smoke at WOT.
Has wispy white smoke on idel and is still a blue tinge through to three quarters throttle.
I ordered a carb rebuild kit to see if that would help but i havent got it yet.
I played with the idle are screw a little bit but it did not raise or lower the idle speed any. I can august by ear but it was so rough at idle that i could not hear any difference in the idle.
Now when i timed it the T mark on the fly weal was right on but the dash makes on the cam gear was off about two millimeters below the top of the head on the right side and on the left side it was two millimeters above the top of the head. And yes the cam lobes where down. it looked like it was about a quarter of a tooth off but that is as close as i could get it.
Any ideas what i have done wrong? :icon_ cry:
 

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Either out of timing, or your jetting is way off.

Welcome to the site, someone else will chime in.
 

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Discussion Starter · #3 ·
How would i get the timing any closer. Is the timing chain stretched and would a new one fix it. I am going to look at the Jets today and will get back to you about the size
 

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Yeah I'd say you jets are to big.
 

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Yeah I'd say you jets are to big.
Some of them, he said he was still getting blue smoke at certain spots in the RPM range.

Try the jets first, much easier than a timing chain.
 

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What size piston kit did you use? what jet sizes do you have in it now? the smoking could be oil deposits in the exhaust system. What does the spark plug look like? is it wet or dry? when you installed the valves did you lube the stems and twist them trough the seals? If not you may have nicked the seal.
When you installed the cam chain tensioner did you leave the slack side of the chain towards the tensioner? if not you sound like you may be a tooth off, also did you install the cam with the lobes facing downward intake would be around 5 oclock and exh would be about 8 o'clock.
 

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Discussion Starter · #7 ·
I used a Wiseco 12/1 compression piston stander size. I just went and looked at the jets the idle is a 35 and the main is a 125. this 250x was rode for a long time smoking before i got it because the exhaust has significant carbon build up on it. the plug is black and dry. yes the valves where lubed and worked through.
checked the timing chain before and after and its as close as i can get it to stock and the lobes where down to. i just might have to buy a new one not sure if that could be my problem though.
 

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No if your chain is only that far off your not stretched enough. Mine is like the exact same about a half a tooth off and it runs fine. I would say its all in your carb.
 

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Discussion Starter · #9 ·
Thanks for the reply.
That is what i was thinking too. I just came in from working on it and it is getting a little bit better every time i take the carb off and clean it. I have cleaned the carb like 4 times now and don't understand why i haven't got it cleaned yet. the tank is clean and it has new gas in it. It just smokes a little bit at an idle and still has black smoke at WOT but not a lot.
 

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Your probably jetted wrong. The smoke at idle is probably just the deposits in the exhaust but the smoke at wot is probably the wrong size main jet.
 

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Are you taking the jets out and poking through them?
 

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Discussion Starter · #12 ·
I used a Wiseco 12/1 compression piston stander size. I just went and looked at the jets the idle is a 35 and the main is a 125. this 250x was rode for a long time smoking before i got it because the exhaust has significant carbon build up on it. the plug is black and dry. yes the valves where lubed and worked through.
checked the timing chain before and after and its as close as i can get it to stock and the lobes where down to. i just might have to buy a new one not sure if that could be my problem though.
What would make the stock jet size to be to big?:confused:
 

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1/2 tooth off on the timming chain won't cause it to run bad..mine is 1/2 off..and it runs great....something is not right with your carb..settings..so forth..go back through it....make sure your not poking too large a wire through the jets..i always use one wire from a wire brush..anything bigger than that will distort the jet size. check your pilot/air/fuel mixture screw..make sure it's set right..and if you took it out..make sure you didnt blow the tiny o-ring out from the bottom of it !
 
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