cb500t carbon fouled right plug

[hansimusmaximus]

i have a 75 honda cb500t with about 6,000miles on it. i've been fouling plugs like crazy lately on the right side only and they're all carbon fouled. i've been toying with the air/fuel mixture to try to get it to stop but i really don't think this is it. it does not shoot blue smoke or smell like it's burning oil at all. when i put a new plug in it runs great for about 20 min then it starts to sputter/miss on the right cylinder at about 1/4 throttle or when i get higher into the rpm's. i'm thinking it may be caused by a weak spark. any help will be appreciated!!

thanks!

 

[Blake]

What sort of gas are you running?

Is the ignition stock?

Any engine mods on the bike?

I ask because I've been having the same problem lately.

 

[adamrjordan]

I suggest checking your points for the correct gap. They tend to get out of adjustment easily on our 500t's and could be causing your symptoms. They should be 0.3 to 0.4 mm. Let us know what you find.

 

[Gage Werke Composites]

Check your carb slides. One might be stuck open. At low RPMs it will let way too much fuel to that cylinder, thus fouling that plug. Those 450 and 500t carbs are very finiky when it comes to any gunk on the slides.

 

[Swagger]

+1 on all suggestions here.

Check all these then start looking at valve seals on that side. Worth doing a compression check...
best of luck amigo!

 

[Wee Todd]

the mention of 20 mins,,,,worn guides or valve seals don't add up,,,carbon fouled as in real black and sooty????????? sounds like a stuck float,,,,or worn float needle and seat,,,,or a pouched float(sinking into the bowl) good luck