Help! My bikes eating spark pugs.

[92_CR250_fmf]

My plug went last weekend on my 92' CR250 (B8EG) so I replaced it today with a B9EG (as recomended by my dealer) but that went after about 40 mins of riding.

I put a replacement new B8EG in & it started first kick.

The plug that came out was sparking a little when tested, but in the wrong place. Instead of it jumping the gap, it seemed to be dancing/tracing around the electrode & ceramic base.

Colour was good, nice brown colour, so no wet fouling going on here, In fact, it still looked brand new.

I have checked the coil & black box. These both seem fine, but is one busted? My friend says he had this problem on his 96' RM 250 & he replaced the coil & all was fine.

Does this sound like my problem? I'm out on it again tomorrow, but bet your bottom dollar it'll happen again.

What do you lot think?

Cheers,

Gwaredd.

 

[atc3434`]

Perhaps a bad plug, try a few more, see if it happens again. I suppose it is possible that the coil starts breaking up when it gets hot, but probalby unlikely that it wouldnt' just fail altogether.

 

[Joepro9]

a cdi would do that.

 

[scairns]

You should be using the BR8EG (resistor) the non-R plug apparently will case you ingition to live a shorter life.

 

[92_CR250_fmf]

92' CR250 keeps eating spark plugs

I wonder if I could pick your brains, as this problem I have is driving me crazy!

I've got a 92' CR250 which is great except it keeps eating spark plugs. It tends to eat them every 30-45 mins of riding, but when I pull them, they are still new looking with no damage whatsoever, whowever the spark traces around the electrode & ceramic base. I've gone through 3 plugs now (BR8EG & BR9EG) & I'm on my 4th in 2 weekends.

Now, 2 sundays ago I spotted fuel pouring from my carb overflow & no ammount of tapping the float chaber would stop it, so I went home & stripped the carb to find a load of crap in there.

Carb cleaned, I fired her up & went back out & it ran for over an hour, stopping & starting no probs untill I fell off.

Started it up this sunday gone & it ran for around 5 mins then it stopped. Changed the plug again with a new BR8EG & it went 1st kick. This time it lasted for a good hour & didn't pack up, but I was riding around a tight 1st & 2nd gear circuit wheras we usually ride through woods & fast tracks etc. The fuel leaking has stopped since I cleaned it by the way, so I don't think this has anything to do with the problem.

The bike is fitted with a FMF gold series pipe with what looks like a a 'Bill emins?' signature on it. I presume it is jetted to suit this pipe as when the plugs are pulled they are golden brown. I run the pre-mix at 150ml of silkolene oil to 5ltrs of 97 octane unleaded.

The only other thing I can think of is a faulty coil (something I've heard CR's suffer from, is that true?) Should I replace the coil (£50ukp) for safetys sake or risk breaking down again? My freind whom I ride with had a similar problem on his 96 RM 250 & a new coil cured it, even though the shop who tested the coil said it was fine.

It's a pain breaking down all the time & having to replace the plug & head home.

What do you think it could be?

Many thanks in advance,

Gwaredd Steele, Wiltshire, U.K.

 

[Fark]

Do you have a freind with the same bike? Swap out the coils.

Better yet, get yourself a service manual and VOM and take the readings. Have a friend tap the part lightly to see if there are any breaks in the voltage or resistance (intermittent open circuit).

 

[MrLuckey]

One note about taking resistance readings on coils. I have seen many good coils test bad with a simple resistance check and many bad ones check ok. If its WAY out of line I'd probably replace it but it can be like ohming out a motor, unless there is a load on it you may never know.
Good electricians use a megger on motors for good reason.

 

[Fark]

Good point. To this day I have never seen a megger however. Link me up man!

 

[MrLuckey]

Some B&K models:
http://bkprecision.com/www/np_searchmodel7.asp?lf=Insulation+Testers

A more modern one than I have used before:
http://www.testequipmentdepot.com/AEMC/megohmmeters/1039.htm

Build one yourself (no idea if it would work worth a damn or not):
http://www.piersononline.com/tips/may2000.cfm?srcID=1