Which plugs & what gap for '82 GL1100 with '77 cams?

[Sidecar Bob]

This is part of my ongoing Mr.H's new engine project. It is an '82 1100 engine and will have '77 cams, Dyna S ignition with GL1500 coils and '79 carbs.

The same ignition worked well in the 1000 engine with D8EA plugs with the stock 0.6-0.7mm gap.

Honda specifies the same for the '80/81 1100 and DPR8EA-9 with 0.8-0.9mm gap for the '82.

According to the attached chart the P means projected insulator type and the 9 indicates the gap. The stereo doesn't pick up any noise from the non-resistor plugs now so I should be OK with either DP8EA or DPR8EA.

That brings us to the gap: Should I just use the 0.8-0.9 gap specified for the 1100, the 0.6-0.7 specified for the '82 or split the difference with 0.7-0.8mm?

[CYBORG]

according to the chart, the nine indicates "heat range". which is dependent on how the bike is used. I know you knew that, just correcting for those who might not

[Sidecar Bob]

I knew that. My 650 uses DPR8EA plugs but I have a set of DPR9EA that I got for diagnostic purposes.

[Whiskerfish]

I would think that those 1500 coils being newer are probably hotter than the stock 1100 and with the dyna I would definitely try the wider gap and see how it does.

[ericheath]

Somewhere along the way I read that Honda went to the P for better placement of the spark. I run DPR8EA9 in my 1200 with 77 heads. I tried the 77 plugs and couldn't tell the difference.

[Briang]

Iridium Plugs, without a doubt. Powerful spark, very long lasting, an instant tuneup.

[Sidecar Bob]

I do NOT think longer lasting plugs are a good idea. Plugs need to be removed every year or so to prevent this from happening

[Sidecar Bob]

I just realized that plugs are the one thing I never got around to buying and I've started re-assembly so I looked back at this thread to jog my memory about which ones to get and I noticed this:

According to the attached chart the P means projected insulator type and the 9 indicates the gap.

according to the chart, the nine indicates "heat range". which is dependent on how the bike is used. I know you knew that, just correcting for those who might not

I was talking about the 9 at the end of the plug number which indicates the gap in 0.1mm increments, not the heat
range number in the middle of the plug number (which is 8 in this case). I guess I missed that when I replied

I knew that. My 650 uses DPR8EA plugs but I have a set of DPR9EA that I got for diagnostic purposes.

[ericheath]

The 9 at the end is too large a gap for my bike, 1200 with 77 cams/heads and PowerArc ignition. I would try and secure some 8 or even 7 as bending the 9’s down to the right gap is tricky. You end up with a hooked tip, the right gap at the tip, but larger towards the back.

[Sidecar Bob]

I don't think they make them; At least I can't find any DP8EA or DPR8EA plugs other than the 9 (0.9mm) gap on the web.

[ericheath]

I had some a few years ago, but last summer all I could find were 9’s. They may be fine for yours with a Dyna and 1500 coils. They worked in mine before I went to the PowerArc system. They give up a little bit when I’m going 1000rpm more than I should be.