YZ starting problems

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Jun 28, 2003
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#1
Maybe some of you 2 stroke gurus can help me out. I recently
picked up a 95 YZ 125 that looks like it has been beat on pretty
hard. I cleaned it up and put a new top end in only to find that it
is VERY DIFICULT to start. Once it starts it seems to run OK, although it won't idle(maybe the air/fuel screw?). Low end power is a little weak, but that is kind of what I expected from this bike anyway.
The top end was already torn down when I got the bike so I don't know how it ran before.

Any help would be greatly appreciated.
 

atc3434`

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#2
Is it hard to start only hot, or hot and cold alike. I know my bike starts very different depending on it being hot or cold. Cold, I use full choke, and no throttle... touching the throttle defeats the purpose of the choke. When my bikes warm, I give her just a little flick of throttle as I kick over and it starts right up. I would start by getting her idling, and see if the clears up the starting problem at all. To do that, see if you can do some research on stock settings for the bikes idle screw and air screw. Somebody else here might be able to get you a good baseline. Another thought to consider, is possible weak ignition. Also, and airleak will make for wicked tough starting. Start by checking the obvious stuff, clean filter, good gas, fresh plug. Then start looking for weaknesses from there. Does it pull pretty good on the topend of the powerband? Hope this helps...
 
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#3
Thanks for the info? For some reason I have a hunch it may be an airleak
problem, but I could be way off Could worn/bad reeds be a factor?

The bike is hard to start both hot and cold. Once running I usually try to stop on the top of a hill so I can just coast down in gear to get her running again.
I have litteraly ruined 2 pairs of boots kicking that thing over and it is bugging
me to no end. I have alway ridden 4-strokes so this is all new to me.

It does seem to pull good on the top end.
 

atc3434`

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#4
Hmmm... forgot all about worn reeds, that'll make for hard starting for sure. And an airleak doesn't help either. Maybe a leakdown test is in order. And a new set of reeds doesn't cost much, and is a good investment anyways on an older bike. Goodluck! You've definitely got a problem somewhere, a 125 either starts right up or doesn't. If it doesn't, its got a problem. :|
 
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#5
I am glad to hear that the reeds are suspect as I have a set on order. That would probably be the most simple fix.

Thanks for all your help- I will post my results once I get the new reeds.