CR250 weak spark? 2001.

[tfreder1]

2001 CR250. Ive been trying to figure out this problem for weeks now. The bike starts with a new plug. I can ride for about a half hour before the plug fouls. There is a noticble power loss and alot of oil blowing out exhaust. The bike stalls then I replace the plug with a new one and it will now run fine for another half hour or so. The spark is not as strong as I think it should be. (comparing to my snowmobile.) This problem has seamed to of got worse over time.
This is what Ive tried.(in order)

I run Bel ray HR-1 32:1 with 92 octane.
Tried 40:1. Tried Yamalube.
New engine seals.
Carb rebuild. stock jetting. stock reeds.
Cleaned and adjusted power valve.
Replaced the stator, cdi box, coil and plug cap.
Tried changing the timing and pickup coil gap.
Checked all wires for breaks.
Have not replaced pickup coil.

Thanks for any help.

 

[Cleric]

you might check or try replacing your crank seals and bearings, My Yz had a smiliar problem and it ended up being my crank seals

 

[magneto]

Check for proper float level. Better yet, dump the stock Mic carb and replace it with a Keihin carb from a 2000 model CR250. Parts cost is approx $200 from Service Honda and it is a straight swap over. Jetting will be much more consistent and low end throttle response is greatly improved. There is a huge thread somewhere on this site that talks about this swap.

You can lean out the jetting on your current carb. How far are you above sea level?

 

[magneto]

Also, is your air filter clean and properly lubricated?

(BTW, I run Premium pump gas/Golden Spectro at 32:1 in my 01 CR with no problems however I don't think oil brand or type is your problem.)

If I recall correctly the spark on my 01 doesn't look that strong either however my bike has never fouled plugs or been hard to start.

 

[tfreder1]

Thanks magneto

Thanks magneto. I switch the carb and lean it out sum like you suggested. I also put in a BR8EIX Platinum plug. I haven't gone riding yet but just around the house its 10 times better.