[Rattlebattle]

Please forgive my ignorance, but what is a quench chamber (in layman's terms)? Is it to do with the cylinder head design? It's a term I've not come across before.

[suitcasejefferson]

Do a lot of maintenance and ride slow, it should last a long time. But it does vary considerably. Some break down on the way home from the dealer, others go well over 50,000 miles with no major issues. Just don't expect Japanese or even Harley reliability from it.

[mattsz]

Do a lot of maintenance and ride slow, it should last a long time. But it does vary considerably. Some break down on the way home from the dealer, others go well over 50,000 miles with no major issues. Just don't expect Japanese or even Harley reliability from it.

+1.

If you're lucky enough to end up with an excellent motor, then... well, you'll have an excellent motor, like GHG says.  If not...

[Blairio]

My Electra was doing great until the £1.50 auto compressor pin decided to split into its two component parts. One is the pin itself and the other a small actuating lever that fits into the side of it. Would any other brand have a similar failure in such a basic small part (think also of the failed woodruff key on the 'Himalayan' thread)? I don't know. Probably not.

I was lucky that the actuating lever part of the auto decompressor didn't go walkabout. Imagine if it has lodged between the cogs that drive the camshafts at 3000 rpm?  Ouch.

[Rattlebattle]

I believe that any manufacturer can produce the odd rogue bike that slips through the net. A recent post on a Triumph forum concerned the failure of a cheap circlip in the gearbox, necessitating an engine strip and replacement gearbox under warranty. What you don't get is bits of shop rag and who knows what in the oil at the first oil change. Jap bikes are probably the most reliable, but they're not infallible either these days because they all rely on sensors that can fail.
There's no proof that a mollycoddled UCE will last any longer than one that is thrashed as long as it is serviced. With a roller bearing big end lugging the engine isn't doing it any favours. The recommended run-in speeds are ludicrously slow - a hangover from the old iron barrel jobs with their floating bush big end. As has been said, you either get a good 'un or not. If not, riding it slowly and changing the oil every five minutes won't prolong its life much. Each iteration seems to be better: by 2025 they should be excellent.

[ace.cafe]

Please forgive my ignorance, but what is a quench chamber (in layman's terms)? Is it to do with the cylinder head design? It's a term I've not come across before.

A quench chamber may also be called a squish chamber or a closed chamber.
It means that a portion of the head surface above the piston is flat, and the piston crown has corresponding flat surfaces. These surfaces come very close together at TDC. When they do, the fuel/air mixture is "squished" out of the small gap, and is propelled across  the combustion chamber,  giving a faster and better burn. The "quench" happens at the same time, because the narrow squish gap at TDC is too small for a flame front to burn inside, so it is said to be quenched in those areas. This reduces heat loss into the casting surfaces during the critical time around TDC.the combination of these effects typically improves the combustion efficiency of the engine.

[Rattlebattle]

Thanks for the clear explanation; I'd heard the term squish before but not quench. Thanks again.

[Adrian II]

This is the old AVL Electra-X combustion chamber, the UCE/EFI Bullets are similar, the Electra-X uses a flat-top piston, I believe the EFI models use pistons with slightly dished crowns.

Ace's billet heads (and the occasional AVL head he has reworked) use a more compact chamber design.

A.

[TomJohnston]

Short addition to Arizoni's 28 hp note. I see it dyno's at the rear wheel at 18 horse.

[Richard230]

Short addition to Arizoni's 28 hp note. I see it dyno's at the rear wheel at 18 horse.

That reminds me that my 1964 Honda 305 Super Hawk claimed 28 hp (if I recall correctly), but typically put out 18 hp on a dyno. You just can't trust manufacturer horsepower claims - especially when they make them public.  BMW is fairly trustworthy, but even they tend to measure the power at the crank and it looses about 20% by the time it gets to the rear wheel.

[Narada]

Then there's the SB/GHG UCE dome top piston... I can't explain the squish characteristics but it will cause the earth to shake beneath you! 

On one occasion, as I was passing a young lady by the curb, she just about jumped right out of her yoga pants!  When I checked my mirror she was still in the air... It was quite impressive. 

[Ice]

In addition to the difference between at the crank and at the rear wheel another source of power loss is fuel.

 Ethanol laced reformulated "gasoline" has an  energy content of 110,000 BTU per gallon compared to 124,000 BTU per gallon of unadulterated gasoline. Less energetic fuels give less power.

It would not surprise me at all if factory published torque and horsepower figures we're derived using plan gasoline.

[gashousegorilla]

Then there's the SB/GHG UCE dome top piston... I can't explain the squish characteristics but it will cause the earth to shake beneath you! 

On one occasion, as I was passing a young lady by the curb, she just about jumped right out of her yoga pants!  When I checked my mirror she was still in the air... It was quite impressive. 

   LOL !    Yeah...Tumble, swirl and squish.  Plenty of that !   

Short addition to Arizoni's 28 hp note. I see it dyno's at the rear wheel at 18 horse.

  Inertia Dyno's kinda suck...  especially when they plunk in an " average gear ratio" when doing a test.   BUT, they are pretty much the "accepted"  method for at the wheel numbers on a bike.   Real world, I bet they are doing a  little better then 18-20 at the wheel.

  Coincidence with the claimed 28 HP ....I don't know  ?   But here is a very near to stock bike not using an inertia Dyno and it is also "at the wheel".  Just a slip on muffler, o2 removed and  intake cam rephrased.  AND running too rich, so there is more power to be made there ... another horse or two maybe ?  Running regular old 87 ethanol laced pump piss... A slightly higher BTU content WOULD be nice.     The cam re-phase is just shifting the power up a bit in the RPM range.... lined up straight on the marks, the power would come in with similar number's , but at a lower rpm me thinks.

[gashousegorilla]

  Inertia Dyno results ?  Same curve... yet it shows about 20 at the wheel.   So go figure...

[Ice]

This is the old AVL Electra-X combustion chamber, the UCE/EFI Bullets are similar, the Electra-X uses a flat-top piston, I believe the EFI models use pistons with slightly dished crowns.

Ace's billet heads (and the occasional AVL head he has reworked) use a more compact chamber design.

A.

 UCE for comparison.