FC, What was the cause of your mate's engine failure?

Automatic primary chain tensioner ratcheting up too tight.

So what tensioner do they recommend? If it's this one I wish you well with the noise.
Best option I've seen to date is to drill and tap the original tensioner so you can set it and lock it and still have a bit of spring movement, no noise and doesn't ratchet up, it is as hard as hell though and takes a bit of drilling, been meaning to do it to mine.

Thanks Fc sorry I was confused and thought he had a manual adjuster installed. 

You would think that Hayden would make something like the M6 tensioner we use on Evos.

FC I can't speak for everyone that has used one of the SE adjusters, in my case it was horrendous, I loaned it to a mate, he fitted it, laughed and sent it back, I initially used it when they first made them, 2012? Not sure, my mate used it this year, heap of blokes in the west got into them when they came out, some said noisy some said not, did read that if your runout is good on both sprockets and you use a new chain they are ok but I have no personal experience there.

They do.,, been running an M6 on my twin cam for years.

I have been using the M7/6 on mine for about 5 years maybe longer.  Make a hell of a difference

What are M6 M7 ones?

Google 'hayden' primary chain tensioner.  They have been around since the Evo days and are bloody awesome.

Put a Hayden Tensioner on my Glide years ago, is fine still, but only a cam etc. up grade.

Big torque can bugga the aftermarket tensioners that have springs, lots of happy campers out there though.

Another option to the SE adjusters, don't know if it is any different in the noise department.

In my case it was a very loud growling whir, I cannot stress the loud bit enough, I would of run it as a drag bike but not as a road bike, my chain was good, crank was good, have not tried it on my current bike.

Jeez Hoody I don't know for sure but it didn't make that racket with the original tensioner even though it was bent on the bottom and it didn't make a noise with the newer stock one I replaced it with, I put it down to chain on material and harmonics, oil was fine, the bike, 06 Dyna, did another 50k afterwards with no primary issues before I sold it.

I have 2 new SE manual adjusters in my shed, been there since they were released. Same reasons as Hilly.