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Spark Plug Question for 1966 CA77

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norm-ormond66305 Member
Posts: 14
Joined: Mon Feb 13, 2006 3:28 pm
Location: Ormond Beach Florida

Spark Plug Question for 1966 CA77

Post by norm-ormond66305 » Mon Aug 11, 2008 9:10 am

I'm having problems with fouled plugs after two rides. I read some of the posts but could not find any related to this for my 66 CA77.
My mechanic told me to switch from a NGK D8HA to a D7HA but, I cannot find this plug. I called NGK tech support and the person was surprised when he went to find it for me and evidently they stopped making the 7 for some reason. He said I could go to a D6HA but that was a pretty big two level jump.
Anyone out there tried this yet? Or have a alternative plug I could use?
When I put new plugs in it, the bike runs great for about 20 miles...then the plugs are fouled bad. My spark is fine...
thanks in advance

onchiman Member
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Location: Adirondacks

Post by onchiman » Mon Aug 11, 2008 9:48 am

Plugs fouling that quickly doesn't seem right even if it is a colder plug. Sounds like it's running rich. I would suspect you have a fuel issue. Did you strip and clean the carb completely? Air filter clean? The D6HA plugs are available and according to Bill Silver's book, are the ones he recommends for the CA77. That's what I'm running with no problems.

norm-ormond66305 Member
Posts: 14
Joined: Mon Feb 13, 2006 3:28 pm
Location: Ormond Beach Florida

Reply on your tip

Post by norm-ormond66305 » Mon Aug 11, 2008 11:45 am

Yes, the carb had beens stipped and it has a "new" air filter ( K & N) up inside... I will go ahead and try the D6HA plugs. The NGK tech told me to check them after about 30 miles to see how they look to make sure they are firing okay.

young4vr Member
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Joined: Tue Jul 11, 2006 9:08 am
Location: Columbus, OH

Other Brands besides NGK

Post by young4vr » Tue Sep 02, 2008 8:36 pm

I was wondering if anyone has tried other brands beside NGK, I pulled up the numbers for Champion 888 or P8Y or Autolite 4173.

I just had an issue when my 1966 CA77 would run great for about 20 miles, then the right side would start to backfire and then just stop firing. It just seems odd that the NGK are being sold by the case on EBAY.

Just an observation going to give it a shot with another brand, or is there that much difference between the D6HA and the D8HA. Don't really know the difference, more of a computer guy than a mechanic.

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Post by e3steve » Wed Sep 03, 2008 4:23 am

The lower the number, the hotter the plug (DH6 / 7 / 8HA), so find a Bosch, Denso or Champion equivalent to, say, a D6HA and then go for the next stage of colder plug from that manufacturer (or hotter if you x-refer a D8HA!).

Bosch always had a good reputation with their surface-discharge technology (multiple electrodes) which creates an even and 'complete' combustion -- allegedley......

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