Author Topic: the trashed head and piston photos  (Read 6086 times)

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gremlin

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Reply #15 on: April 02, 2015, 02:11:47 pm
So, ACE .....  are you saying our UCE bullets should cruise at 60 MPH ?
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ace.cafe

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Reply #16 on: April 02, 2015, 02:54:35 pm
So, ACE .....  are you saying our UCE bullets should cruise at 60 MPH ?
I think it would be a good idea for longevity, although I could stretch it to 65mph, since they seem to be okay there.
If the bike is one of the ones that vibrate severely at 65, then I'd try to work around that, and maybe stay below.
I don't want to be alarmist about it. Obviously some people are doing it, but most engines really are not intended to be run for long periods at near maximum output. It's my "rule of thumb" that I use as 75% of max for longevity, and others might differ.

As a comparison, our Fireballs do 100mph, and we recommend(and have verified) 75mph for long term cruising for several hours. So we do use that across the board for our recommendations.

The Pomeroy Dictum would concur, since that recommends <2500fpm piston speeds for longevity, and that would be around 4200 rpm on the UCE. That's about 65mph with stock gearing, roughly.
So, maybe I'm a touch on the conservative side, but with aircooled stuff at high load near max, it might not be a bad idea to be. Especially in the summer.
« Last Edit: April 02, 2015, 03:01:45 pm by ace.cafe »
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Bulletman

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Reply #17 on: April 02, 2015, 05:42:54 pm
 I have a C5 2011, 80% of the time I'm topping the bike at 76 to 78 MPh, my highest gps speed has been 82mph, which at times I've ridden at for 8 to 10 mikes straight on HWY 4 back roads (flat road, not much wind) heading from Stockton towards Copperopolis, I guess I've been lucky to have made it to currently 12006 miles. I've not had any significant issues except for the old Wobble issue, a new vibration issue that changed after I changed the tire pressure, a loose bolt in the left case, and just recently found a crack in the muffler, which I'm replacing with a bell-end/ Cocktail shaker.
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ace.cafe

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Reply #18 on: April 02, 2015, 06:22:38 pm
I have a C5 2011, 80% of the time I'm topping the bike at 76 to 78 MPh, my highest gps speed has been 82mph, which at times I've ridden at for 8 to 10 mikes straight on HWY 4 back roads (flat road, not much wind) heading from Stockton towards Copperopolis, I guess I've been lucky to have made it to currently 12006 miles. I've not had any significant issues except for the old Wobble issue, a new vibration issue that changed after I changed the tire pressure, a loose bolt in the left case, and just recently found a crack in the muffler, which I'm replacing with a bell-end/ Cocktail shaker.

All I'm saying is that for longevity purposes it might not be the best idea to operate the machine at redline and heavy load for extended periods.
Operating the machine at its limits can take its toll.
It might do fine for quite a long time, ..... or it might not.

It's up to the owner to do what he wants to do with the bike. I have no intention to try to tell people what to do with their bikes. However, I do have some understanding of engines, and this is my point of view on the subject.
« Last Edit: April 02, 2015, 06:26:31 pm by ace.cafe »
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Bulletman

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Reply #19 on: April 02, 2015, 06:44:18 pm
@Ace
My comment was basically that I do run my bike rough, I don't recommend anyone taking their bikes to the Max, like anything else, everything is good in moderation  ;) unless of course you feel the need for speed ;D
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gremlin

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Reply #20 on: April 02, 2015, 08:04:17 pm
I've only got 5000 miles on my 2011 B5, but, I assure you over 75% of that was spent near WOT on the beltway....  accelerate to top speed then reduce the throttle-plate until it speeds up "just a smidge".   8)  crappy mileage, I keep ahead of most traffic ......  8)

The AVL piston upgrade is still sealing itself (It's been in less than 400 miles) but the bike seems happy with this "abuse".

« Last Edit: April 02, 2015, 08:07:38 pm by gremlin »
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Reply #21 on: April 02, 2015, 08:14:49 pm
i was commuting fron dixon ca to davis(approx. 12 miles one way) and while not wide open, i did have to occasionaly explore the upper limits of performance. never gave any indication of unwillingness to do so, and as previously stated was cruising at 55mph when the valve let go.
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gremlin

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Reply #22 on: April 02, 2015, 08:19:32 pm
............. was cruising at 55mph when the valve let go.

I think that is the key to understanding this failure.  You were running in closed-loop and the injection was keeping things nice and lean for the catalytic.  Don't know if you have any airbox modification .... 

The exhaust valves on these UCE bikes sure do *look* like they run Hotter than Hell whenever I look into the port......
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gizzo

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Reply #23 on: April 03, 2015, 09:40:42 am

I wonder what would have be seen if there was a camera within the cylinder at the time of failure

Most likely a smashed into pieces camera as well as the other parts?
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ace.cafe

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Reply #24 on: April 13, 2015, 01:18:57 pm
Just in the interests of adding to the data on this, I have just received another UCE head with this same damage of broken exhaust valve, hole in the piston, and the chamber beaten up.

In this case, I am aware that the bike was ridden a significant amount of miles on the highway after knowing it was exhibiting engine problems, and eventually failed with the broken exhaust valve. I advised this owner to cease riding the bike after he reported that the bike was knocking, and he decided to continue the journey.
So, I would say there was abuse in this case.
« Last Edit: April 13, 2015, 01:23:12 pm by ace.cafe »
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gremlin

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Reply #25 on: April 13, 2015, 01:33:32 pm
....... there was abuse in this case.

tell us what you *really* think.  :o

any idea what was causing the detonation ?
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ace.cafe

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Reply #26 on: April 13, 2015, 01:53:55 pm
Well, the first call that I got from him was about a bearing knock, and he wanted to know if he could make it from New Orleans to NYC like that. I said he should trailer the bike there, and then fix it, to avoid further damage. He decided to try to make it, and it didn't.

So, there are all kinds of possibilities with this. I really can't say with any certainty how all the symptoms added up to the eventual failure. I might initially suspect that the bottom end failure had effects that spread out the the other areas of the engine, and also the oil may have been compromised.

With this kind of severe damage to the piston and chamber, sometimes it is difficult to see signs of detonation. I will look closer at the spark plug to see if I can detect anything on there.

I have the plug and the head of the exhaust valve in a baggie here, and will look at them further.
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ace.cafe

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Reply #27 on: April 15, 2015, 12:09:50 am
I was over at the shop today, and we had to make an order of custom valves for a stock head repair job, so I had them order an extra box of the custom exhaust valves that are exactly like the stock ones, so they could drop in right without any special work. You would just need to know how to remove the head, have a valve spring compressor to remove the valve, and put the new one in, and put it back together.

So, if anyone is getting paranoid about their exhaust valves, we'll have some nice quality replacements.

Just FYI.
« Last Edit: April 15, 2015, 12:55:00 am by ace.cafe »
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gremlin

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Reply #28 on: April 15, 2015, 01:36:54 pm
stainless, or, titanium ?
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ace.cafe

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Reply #29 on: April 15, 2015, 03:58:19 pm
stainless, or, titanium ?
These will be stainless.

We have not had good experience with titanium exhaust valves. Even with the BeCu valve seats installed, the titanium exhaust valves did not survive in the racer, so we put a stainless one in, and it is doing fine. I have spoken with other builders who say the same thing.
No problems with titanium intake valves so far. The racer has titanium intake and stainless exhaust.
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