Vintage Dirt Bike Q & A

I've got a '80 Cr125 it had been sitting for a while before I got it.I cleaned the carb out and gas tank went to a #175 main and dropped the needle to the lowest notch to lean it out.I'm having trouble grtting it to come on in the middle(it idles fine)but it misses and jerks in the middle before it cleans out on the top.Any suggestions would be appreciated.

There are some in these parts that are gurus on the CR125R. However if you moved the clip to the bottom position, you made the jetting richer...

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Bottom clip sounds rich to me too. Too much fuel, sounds like its loading up in the middle and then cleaning out on top end. Move the clip up to the middle and see what happens. Why did you change the main jet and what was in there? 175 should be stock.
Keep us posted, always nice to hear how it turns out.

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Garry Mainer
#33m (retired)
Honda Cr250r 1980
Honda Cr250r 1980
Yamaha TY250C 1976
Arctic Cat 650 H1 2007

After further review I've also found that the pipe has some cracks in it.Somebody tried to weld it but it looks like crap I think this is part of the problem.i think I'm gonna rebuild it from the bottom up just to eliminate the crank seals and anywhere else it could suck air.According to the manual dropping the needle to#5 should lean it out unless i'm reading it backwards.I've got a new mikuni but it's missing the needle where can I find the spec settings for it.

You correct that dropping the needle lower makes the jetting leaner. You do this by moving the clip on the needle higher from postion #5 towards position #1. Vintage Elsinores should be able to help you with a jetting baseline for a Mikuni carb on a CR25R...

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF