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Honda cr80 carb question, and jetting problem. Help?

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My honda cr80 has lots of unburned oil leaking out of the exhaust head where the pipe connects to the engine. I tried replacing the seal twice and it still leaks out around the new gasket. The spring is tight and the bolts are tight. The oil smells/looks like it might have a little gas in it.

 

The carb is squeaky clean and the jets are not clogged but it has a 125 main and a 50 pilot and I think it may be too rich. The problem is I have no idea what size my carb is to order jets.... It's a keihin PE but it doesn't say how many mm's it is.

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believe it is a 28mm carb from what i read.. others might know.

 

FMFracing.com lists this for your bike. these results are for a bike with a aftermarket pipe but will work with a stock.

 

Jetting Results

  • Main Jet
  • 122
  • Pilot Jet
  • 52
  • Needle
  • STOCK
  • Needle Position
  • 3RD
  • Power Jet
  • N/A
  • Air Screw
  • 1.5
  • Fuel Screw
  • N/A

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How big of a difference does each size make? Like since it's running WAY rich, could i drop my pilot all the way from 50 to 40?

You could, but shouldn't. Try a 48, or 45. Use your airscrew to determine. Also consider a step leaner needle.

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Ok I ordered both a 48 and a 45, and I moved the needle one notch leaner, but its at the second to last notch already and my air screw is 2.5 turns out, and float is set decently high too. So the carb is about as lean as I can get it and still turns my plugs black. Hopefully the new pilot will fix it.

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I just went from an NAPF 2nd clip, to an NAPG 3rd clip on my daughters RM85/100. It has a 28mm PWK from a KX100. Going a step or two leaner on the needle makes a difference. I also have the stock 28PE, and I just went from the stock NAAH 2nd clip, to NAAK 3rd clip, which is two steps leaner. I was having the same rich problem with it. The 4th letter of the needle mark correlates to the straight section diameter, which effects 0 to 1/4 throttle. Then the taper follows which effects 1/4 to 3/4 throttle.

Edited by magpie5

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