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2002 CR 250 plug fouling issues!


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Hello,

 

I recently purchased a 2002 CR 250. I took it out a few times and noticed that the plug was quite wet and oily but did not foul any plugs. Over the Canadian thankgivings weekend I took the bike up north to do some trail riding and ended up fouling 3 plugs in 2 days. One plug fouled after just an hour of riding. 

 

The bike runs really well in the midrange and top end but hesitates a little bit at about 1/4 throttle. Most signs point towards the bike running rich, however when I pull in the clutch the revs tend to rise. Also when idling the bike takes a while to return to idle after being rev'd. I tried adjusting both the air screw and the idle screw but neither seemed to remedy the issue. (I could get the bike to idle ok with the idle screw almost all the way out but after riding the idle would seem to hang before dropping down again).

 

I have been fiddling around with the jetting. Here is what is in the carb: 

 

Main Jet: 390 

Slow Jet: 30 

Needle: 6-BEY30-74 . Clip is in second position 

Nozzle: S-9 

Gas/oil mixture: 40:1 running Yamalube with 93 octane fuel

 

My altitude is around 900 ft and the temperature has been between 40 - 60 degrees Farenheit. 

 

I switched the clip on the needle to the top position but the hesitation did not really improve and the plug was still wet and oily. I am already one size leaner on the slow jet according to the Honda manual for my given altitude and temp. 

 

What confuses me is that the bike seems to be running rich (spark plug fouling, hesitation) but also exhibits lean symptoms (hanging idle, high rpm's when clutch is pulled in). 

 

I plan on buying a Keihin PWK airstriker over the winter. Hopefully that will solve some of the issues but I don't want to assume that will clear everything up. What else should I be looking for/replacing? I will check into crank seals but am not overly confident in changing them myself. I also haven't lost much tranny oil so I am doubting that would be contributing to the issue.

 

Any help would be greatly appreciated! Thanks in advance!

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I haven't lost much...After a day of riding I took out the oil check bolt and had to lean the bike over a little for oil to come out. I added between 25-50 ml and then rode the next day. Just checked the oil check bolt again and oil came out with the bike level.

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