02 CR250 Fouling Plugs

[PGHRam]

I read some of the other posts about fouling plugs, but I'm still going to post my problem to see what you guys think.

My 02 CR250 is fouling plugs and I can't figure it out. I'm running 50:1 and when the plugs are removed, it looks like I dipped them in oil they are so black. The bike has a ton of power, but I noticed today that it would cut out in first gear sort of like it was cold......but I've been riding for over 2 hours.
There is a lot of spooge out of the pipe.

Any thoughts on where to start?

Thanks

 

[sharky243]

Rich jetting, leaking crank seal on the clutch side, too cold of plug, stuck powervalve, plugged air filter, low compression, weak ignition.... just some possibilities. 50:1 is way too lean, i don't recomend anything leaner than 40:1. It could also be the oil you're useing.

 

[PGHRam]

I hope its the jetting. When I got the bike, the previous guy was running a race plug. Don't know what kind, but it was the kind that had a point rather than a flat tip where you set the gap. He gave me 2 other parts to jet the bike (not sure what they are called).
I've tried a few different kinds of plugs, the air filter could use a cleaning but I don't think that's it, and the bike has great power. Wouldn't I have less power if it were the ignition or power valve? I don't think it's the oil because my friend was using the same gas out of the same can as me. He didn't foul any plugs.
If it was a leaking crank seal, wouldn't I see it on my garage floor?

I guess it's time to learn how to jet the bike. I don't have a manual yet, but I do have one for 97-01. Would it be similar?

Thanks and sorry for all the questions.

 

[sharky243]

The crank seals are internal. One is behind the flywheel and the other is behind the clutch primary drive gear. If i remember correctly the right plug for your bike should be a BR8EG. Make sure there are no other issues with the bike before you start changeing the jetting.

 

[PGHRam]

I started the bike today to let it run for 3 minutes before checking the oil. I noticed when I hit the throttle that oil was coming out of the spark plug hole.
Then when I checked the oil, no oil came out of the screw hole when I removed it. So does this mean the crank seals are leaking? Is this why it's blowing so much oil out of the silencer even though the last mix was 50:1 and my spark plug looks like I dipped it in oil?

If I'm looking at splitting the case, what should I do as far as replacing or checking parts? I've done top ends, but never a bottom. I can do my own wrenching, but I worried about if I have to have a special tool or something for the bottom end???

 

[smahala1286]

you don't need to split the cases to replace the crank seals. Get a repair manual it will come in very handy.

 

[PGHRam]

I ordered the seals today. Should have them by Friday. I hope this fixes the problem.

Thanks for your help guys. I'll keep you posted.

 

[rmc_olderthandirt]

I noticed when I hit the throttle that oil was coming out of the spark plug hole.

How can you be having oil come out the spark plug hole when it is running?

When you checked the oil and nothing came out the over fill hole, how much oil did it take to bring it back full?

I would repeat that operation a few times before I jumped to conclusions. When you start the bike the spinning clutch is going to throw oil around and it will take a while to all drain back down.

Rod

 

[OriginalRider]

oil comes of the spark hole when the spark plug isnt tight.Its mixture not gear saver.

 

[PGHRam]

How can you be having oil come out the spark plug hole when it is running?

When you checked the oil and nothing came out the over fill hole, how much oil did it take to bring it back full?

I would repeat that operation a few times before I jumped to conclusions. When you start the bike the spinning clutch is going to throw oil around and it will take a while to all drain back down.

Rod

Maybe the plug wasn't tight, but I still think I have a seal problem. I was running 50:1 and throwing a ton of oil out the silencer.
I didn't fill the oil back up. I'm going to drain what's in there. I'll bet that it's very low. The manual said to let it run for 3 minutes, shut it off and wait 3 minutes, and then check the oil. That's what I did and nothing came out of the hole. It then says to slowly add oil until it comes out (which I didn't do).

 

[OriginalRider]

Yea sounds like your running on the rich side.That plug might look tight but it might have to go a couple more threads in BUT don't tighten too much!.Also check you needle valve position.I always was told to run 32:1 or 40:1.Also check your jetting sounds way off.What kind of mods do you have?.

 

[PGHRam]

I'm running a R304 shorty. I know the carb has a 380 jet, not sure about the needle position though.

 

[slodad]

Do you know how old the piston and rings are? My son's '02 CR250 was a real plug fouler and it would occasionally suffer from sudden lack of power, then start running fairly well again. It was impossible to jet it correctly until the topend was replaced. Then it became a perfect gentleman. No more plug fouling, great power everywhere.

 

[OriginalRider]

I had the opposite my bike started to foul plugs on a fresh top end.then i dropped a 180 main and adjusted the clip now no foul plugs!