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CB77 spark plug dry fouling?

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Merz64cb77
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Posts: 154
Joined: Mon May 08, 2017 7:42 pm
Location: Mississauga, ON CAN

CB77 spark plug dry fouling?

Post by Merz64cb77 » Tue Jul 10, 2018 7:02 pm

I’m having an issue with my muffler packing deteriorating from what I think is due to excessive heat either from a lean fuel/air mixture or because the engine was just bored with new rings and pistons and things might be a little snug. I took a look at the plugs today which only have about two hours on them and the centre electrode on the left plug is dark on one side and new/white in the other. The right plug has even dark color. Are my plugs fouling? The bike runs well but hot in my novice opinion.

Any idea how to correct the fouling?

I have the clip on the main jet needles in the middle position.

Float height checked ok and the timing is correct.

Thanks for the help
67' CB77
66’ CB77
65’ bomber
68’ hellcat

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G-Man
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Location: Derby, UK
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Re: CB77 spark plug dry fouling?

Post by G-Man » Wed Jul 11, 2018 12:52 am

Hi Jason

Have you checked that the main jets are the same size?

Air leaks on the lean cylinder? You might have a warped carb flange or a cracked/damaged carb insulator.

G
Merz64cb77 wrote:I’m having an issue with my muffler packing deteriorating from what I think is due to excessive heat either from a lean fuel/air mixture or because the engine was just bored with new rings and pistons and things might be a little snug. I took a look at the plugs today which only have about two hours on them and the centre electrode on the left plug is dark on one side and new/white in the other. The right plug has even dark color. Are my plugs fouling? The bike runs well but hot in my novice opinion.

Any idea how to correct the fouling?

I have the clip on the main jet needles in the middle position.

Float height checked ok and the timing is correct.

Thanks for the help
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

Merz64cb77
honda305.com Member
Posts: 154
Joined: Mon May 08, 2017 7:42 pm
Location: Mississauga, ON CAN

Fouling plugs

Post by Merz64cb77 » Wed Jul 11, 2018 5:56 am

Morning G-man

I’ll check those today but I recall both being #135. I didn’t notice any issues with the flange or insulators but will check again.

Can I still ride the bike or will this issue cause damage?

Jason
67' CB77
66’ CB77
65’ bomber
68’ hellcat

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