cr250 eating plugs

[smiffy123uk]

my cr is eating spark plugs a little too often for my liking havnt had it long but sure a plug shold last a few hours, i did notice a couple of particals of water on the old plug when i removed it after couple hours riding i tasted it and i didnt have a taste of antifreeze plus it doesnt over heat can the head gasket weep? and still run ok, or it seems to run ok:

[Roostman]

Id say if you even suspect a blown head gasket it would be a good idea to rebuild the top end. You should also check your jetting with the book. That looks like a '93, I had a '93 that I bought new and kept it for 9 years. It never once fouled a plug! I never touched the jetting from stock either. Had plenty of FMF pipes on it over the years as well. With the stock jetting it ran perfect.

[smiffy123uk]

i must admit the old plug was pretty black when i removed it

[ossagp]

A plug should last for a really long time,,,I change a couple of times a season maybe on the CR500, and it lives on 20-1 (yamalube). Your float would be the first thing I would check, and before that you can try something else: screw the idle/enrichening valve all the way down tight and see if that helps,,you will have no idle,,but that particular circuit is pretty problematic that way. a newer type carb is the best fix, such as a pwk if screwing that plunger down all the way works.

[smithers]

Originally posted by smiffy123uk
can the head gasket weep? and still run ok, or it seems to run ok:

The answer to that would be a negative....water doesnt compress....a motor is basically a compressor...you get water in there and something will have to give...it wont be the water.

[smiffy123uk]

right ok i just dissasembled the carb the main jet is a 178 and the slow jet is 60 needle on the 3rd groove just looked in the book and the 2 jets arnt listed together as a combination also i think that the float wasnt in the correct place so i think i have just adjusted it right, i held the carb so that the float hung down then tilted it back until the fuel flow needle just seated then took a measurement and set it to 16mm. but if i turned the carb all the way upside down the float measurement became smaller still, is this normal or do i need to take a measurement from when the float measurement is at its smallest? hope i made sence in all that

[smiffy123uk]

oh and i will go get myself the standard jets and see what that does

[ossagp]

you are right on the float,,,the keihin and newer type mikuni's all have larger floats now that will compress the spring on the needle. Wasnt alway so, as in the old round slide carburetors.

Give the enrichening plunger a try to if you are still having problems. (dont waste your money buying a new plunger assembly.)

[kCWolf]

check out my thread titled coil resistance...this is the same problem I had...except the water. It would eat a plug in an hour after getting completly oil fouled.

As for the water, water injection systems have been on certain aircraft many moons ago and it was a great way to increase horsepower...now to figure out how to get it going on a bike!

[Aus_Rider_22]

While you got your carby apart I would check your slide for wear as it could be letting in extra fuel causing fouling.