Hi mrcarb, So this would mean the sealing area around perimeter of plastic cover to alloy would have a gap also. ??
If I get a chance I'll measure how thick the filter is on my '73 Tiger which is same filter. Original from new. I'll try to do that later today or by tomorrow night.
I know from personal experience on 650 round filters the aftermarket elements vary a lot in thickness. A good 1/4". Which obviously makes for a poor fit.
Gave up & spent the $ for genuine. They are still made new by original makers for Triumph in 70s. So far as I can tell the only ones that actually fit properly. They are washable & last for years. http://www.copwash.co.uk/
Above is the maker. Various sellers in USA sell them. Call or email seller & ask who is maker.
Not only that, but other makes can/will skew mixture. After months of chasing my tail, I learned a hard lesson on this.
The plastic outer cover is flimsy & distorts easily. The retainer nut should have a special lock washer that sort of looks like spring. Just snug the nut, not tightened like a normal nut at all. If cover is very distorted you may need new ones. Metal repro covers have been reported for sale. I've never been able to find any. I think it's a myth. The early covers fit, but don't look right.