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Start up problem 97 YZ 125

Joined
Feb 4, 2007
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#1
I am soooo tired of this! My 97 YZ 125 has a brand new top end and the bike runs absolutely fantastic, no problems when riding whats so ever, never fouls plugs, very crisp, it's perfect. But, every friggen time I go to start the bike up the next day after riding or whenever (overnight, 2 days, week, whatever) it fouls the plug. I always shut the gas off too. It will start up first kick, but after a minute or so, it will bog out and die. I tried shutting the choke off immediatly after start up, but it still bogs out. So I have to change the plug, then it runs great. What is the problem here?!? I just can't see it being a jetting issue because the bike runs absolutely fantastic. I run Yamalube at 40:1 and use a BR7ES plug.

Please help me fix this problem!!! :yell: :yell:
 
Joined
May 9, 2007
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#2
When the bike sits, the fuel in the carb evaporates, leving the oil behind. When you go ride again, upon start-up the bike gats a big gulp of oil and fouls the plug. Before you start the bike, turn the petcock on, and lean the bike way over until you see fuel run out of the overflow hose, then start it. This will ensure a float bowl full of fresh fuel instead of a float bowl that is half full of oil.
 
Joined
Jul 15, 2007
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#6
almost had the same problem, with mi rm125, but i tried the BR8ES instead of the stock 9 like you said, and it works fine now, but then again because im such a nut trying to keep mi bike mint, i take the plug out wenever im not riding it and plug in an unused plug until i do go out riding, just so that i'm 100% sure the thng turns on wen i need it most.
 
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Feb 4, 2007
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#7
IndyYZ85 said:
BR7 is a bit hot for that bike.. have you tried an 8 or 9?
My bike seems to really like the 7 plug... runs extrememly well on it. 9's always caused problems... and I haven't tried a BR8ES in awhile, I'll probably try it again.
 
Joined
Mar 28, 2004
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#8
I had a KTM 250sx that did the same thing. I used to buy plugs by the case. It actually turned out to be a slide problem from the manufacturer.
 
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Feb 4, 2007
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#10
Well I just tried tipping the bike over before starting it... didn't help. It started up fine and idled for about a minute or so, then bogged out.
 
Joined
Mar 17, 2006
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#12
do you let it just idle to warm up?? if so, 2-stroke race bikes aren't really meant to idle for very long. try starting it up and riding it easy to warm it up.
 
Joined
Mar 25, 2007
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#13
are you letting it warm up properly or just getting on it and going? let it warm up until you can feel heat on the top of the radiator cap then go.
 
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Feb 4, 2007
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#14
sixds said:
are you letting it warm up properly or just getting on it and going? let it warm up until you can feel heat on the top of the radiator cap then go.
It'll start up fine, and I'll blip the throttle every now and then while it's warming up... but then, you'll blip it and it will just bog out... ughh
 
Joined
Jan 10, 2007
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#15
i always run my carb dry before letting the bike sit. it always starts up fine then wen i try starting it three of four days later