I'm not versed on " Stage XYZ " heads, but one of my BP7ES equipped engines with CP cam has 9.5:1 c/r and the other has 10.7:1 with high lift ( 0.504" ) / 282 degree duration cam. Heads are both Racetorations produce ( caveat emptor! ). I once fitted a set of Champion plugs to a Honda 400/4 motorbike I had bought in the early 1980's, I kept the old NGK ones under the seat in the tool tray.

Suitable for any points type ignition system, our Powerspark Electronic Ignition Electronic Kits, and other electronic ignition systems. This last step reduced the soot on the plugs and in the tail pipe, and made the engine run much smoother.Records indicate jets being done in the '80s on the carb. Car was from the Bay Area and is now in Chicago, so not a ton of altitude difference there. It does this thousands of times each minute. Over time spark plugs start to break down, resulting in a poor spark. A healthy engine needs good clean spark plugs.

On 6ES, V-Power or Ultimate + Valvemaster, I get occasional cold-start fouling on my PI. On 7ES it was even worse. This spark plug has corrugated ribs, triple gasket seal, copper core for more effective heat removal, a 21 mm (13/16 inches) hex size, and 0.9 mm (0.035 inches) gap. The guy I was dealing with from Champion told me that they had a 10% failure rate straight from production The [ dated ] information I have is that the 7s correlated to Champion N9Y and the 6s correlated to Champion N12Y, specified for TR5/6 P.I. and TR250/6 carb respectively, by TRIUMPH. So my experience amounts to " going by the book ". EON5, OE004, OE004/R04, OE004/T10, OE006, OE006/R04, OE006/T1, OE006T10, OE111, RN10Y, RN10YC, RN11YC4, RN7YC, RN9Y, RN9YC, RN9YCC,The car ran well before, but I have no idea how long the plugs were in there for. They were normal grey/brown when they came out, and the gaps were probably nearer .70 thou, so imagine a fair while, although the engine has only covered circa 2k miles since a rebuild in 2003. F000KE0P16, F000KE0P34, W175TR30, W200TR30, W6DC, W7DC, W7DCR, WR5D+, WR6D, WR6D+, WR6DC, WR6DC+, WR6DP, WR7D, WR7D+, WR7DC, WR7DC+, WR7DC2, WR7DP, WR8DC4, STK7500, STK7501, STK7594, STK7595 NGK is the brand leader in the UK spark plug market and are the world's biggest supplier to many major car manufacturers. Each and every one of their products are designed to meet the most rigorous standards and are the professionals' choice because of their quality and technical excellence. Their plugs can be found in use by teams in F1, WRC and MotoGP. Put simply, NGK genuine spark plugs are the workhorse at the heart of smooth-running engines around the world.

But coming full circle, you raise an excellent point and I will put in whatever plugs are currently in there and see how she behaves.I consulted NGK in the context of running at altitude (ie Stelvio) and their recommendation was BPR6EIX which is an iridium tipped electrode with a conical shape that they claim provides a better focussed spark. Not tried 'em yet. I know it's been a little while since I've posted. The car is here but still in winter storage out in the burbs, so I only get over there every couple of weeks for a little while since the garage isn't heated and it's 40 miles away (better than 2,200, right?). I'll be bringing it up to my place once the salt has been washed off the roads and the temps come up a little.

The proper correlation between NGK and Champion is the question, and at the end of the day the colour ought to govern the choice.

Switched to hotter BP5ES and Regular gas ......and now it runs better than ever and the plugs are picture perfect after 1,000 miles.