cylinders 3 & 4 not firing

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rapidblue
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cylinders 3 & 4 not firing

#1 Unread post by rapidblue »

So my bike is only running on two cylinders. WTF?

bike was runnign good up until my holidays. Let it sit for a week and now only "running" on 1 & 2.

Haven't got the plugs out yet but, they are only a month old. As are the carbs "cleaned and synced". First thought would be fouled plugs. But there's got to be a reason why two plugs are fouling after a month. Cause might be carbs are dirty and set up wrong, but I just had them done. Do I need to to lose it on the guys at the shop and have them done again?


What gives? I'm frustrated.
80 honda CB750F Super Sport

oldschoolorange
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#2 Unread post by oldschoolorange »

how is your carb setup? 2 carbs feeding 2 cylinders each or 4 carbs? If it is the first setup @ carb) try tapping the float bowl with a screwdriver or taking out the drain to see if you are getting fuel. if you are then check the plugs, after that check the carb and clean it out, I had the same problem on my bike
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rapidblue
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#3 Unread post by rapidblue »

It's four carbs, I finally took the plugs out and they were all fouled, 3 and 4 were worse than 1 and 2. They are black. Not sure if its fouling from fuel or oil. Didn't look hard enough.

Put in new plugs and it runs fine. Obviously there is still a problem. Something is fouling the plugs fast.
80 honda CB750F Super Sport

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bok
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#4 Unread post by bok »

not to be a conspiracy nut, but are you sure they put new plugs in? pull the plugs again after a few miles and see how they are, if they fouled up that fast on you, i would assume they would do so again.
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rapidblue
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#5 Unread post by rapidblue »

bok wrote:not to be a conspiracy nut, but are you sure they put new plugs in? pull the plugs again after a few miles and see how they are, if they fouled up that fast on you, i would assume they would do so again.
haha yeah, they gave me the old plugs. But were they MY old plugs (puts on tinfoil hat....)
80 honda CB750F Super Sport

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stormme66
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#6 Unread post by stormme66 »

check where your HT leads come from. Usual is 1 and 3, 2 and 4, b ut in this case, you might have one coil supplying 3 and 4, in which case this may be suspect.
that's my 2 cents worth.....

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