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Author Topic: Hi-Compression Piston  (Read 5206 times)

geichal

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Re: Hi-Compression Piston
« Reply #15 on: November 26, 2007, 11:56:33 PM »
I do have a RH shift kit and the "improved" clutch pack yet to install.  I have been considering a larger countershaft sprocket, but figure that I had better run her first to really appreciate the difference.
geichal

Peter

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Re: Hi-Compression Piston
« Reply #16 on: November 27, 2007, 01:09:21 AM »
It may be helpful to actually look at the stock Bullet piston.
What I pulled out of my 2003 didn't look very convincing.
It's got cuts in places where people once believed that they were helpful.
Pay particular attention to the circumferential cut under the oil ring.  ;D
Just looking at the thing makes me laugh.
No wonder that there are reports of the piston crown separating.
There is no better way to improve your engine than to put a decent modern piston in.
An alloy jug is a close second.
It just happens that the available pistons have higher compression because who would want to put up with the issues of a TOO LOW compression engine when already there.
The  "Accralite" looked decent to me and is performing well.
You can always use compression plates if compression turns out to be too high.

I don't know if they have changed piston design since 2003.
If you have one like I found in my engine you will need to be verrrry careful.
Talking reliability while leaving such a thing in place makes no sense whatsoever - IMHO :D

Peter

« Last Edit: November 27, 2007, 01:14:11 AM by Peter »

indian48

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Re: Hi-Compression Piston
« Reply #17 on: November 27, 2007, 01:42:49 AM »
To the question LJR asked, what is performance?
My 2 cents:
To the best of my knowledge the IC engine converts just about 25% of the energy in the fuel into mechanical energy, the rest of it lost as heat mostly. And if you take the power losses between the engine and where the tires hit the road to impart motion, I have no idea what more is lost,,,I would guess that in riding the bike, we waste 80% of the energy in the fuel we buy. I would therefore define my performance objective for the Bullet to be to get those figures moving upward as high as they can, and the fun in the Bullet is that it affords the owner a lot more opportunity for those moves, than the modern bike or car, where the only real option one has to walk and not use the vehicle to conserve energy( exaggerating here for drama!). I would define any move that gets that number up to be progress, in my book.
The second objective would be to get the bike to deliver that energy conversion on an on going basis, without intervention other than to keep moving that number upwards( routine/preventive maintenance not defined as intervention here). Which means working on its ability to do what it does on a sustainable basis - in other words, reliability.
How does that sound Larry? Good enough?!
If anything is worth doing, it is worth doing well

LJRead

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Re: Hi-Compression Piston
« Reply #18 on: November 27, 2007, 04:29:12 AM »

Well, I'm not sure if the answer I give will fit in, but today I have been doing some thinking about gear ratios.  When you look at Specifications, the different bike models just say 5-speed gear box, they don't seem to give the gear ratios.   Now all this emphasis going on in the forum on getting that little bit of extra speed without harming the engine has me thinking that maybe someone should think about either going to a 6-speed gearbox accessory or else some sort of kick in overdrive.  Don't know enough about what ratios are used in various bikes, but do know from recent reading that 6 and even 8 speed gear boxes are sometimes used.

Either that or perhaps a change in gear spacing might be in order, giving the ratios typical of the older 4-speed gear boxes for the first four gears, then having a step up to the fifth gear, making it an overdrive.  I can probably cut, modify, or make gears on my equipment, but it would take me years to do so, but looking at the R E gearbox in the parts manual I got from CMW indicates that the outside box is roomy enough and the inside gear arrangement is simple enough, so that maybe an after market gearing system could be produced.  Would there be a market for it?  Don't know.  But one of those whiz bang modern factories in India should be able to design and produce one in a weekend or so.

The R E  seems to have plenty of raw torque to handle more gears.  If it had a still higher gear than the fifth one, or if the fifth one were made higher, then it would seem to have the torque to handle it just fine.  It wouldn't have to be that much higher to handle an additional ten miles per hour speed.  At a time like this I wish I knew what I'm trying to talk about!  But someone on the forum may have that sort of knowledge - hope - hope!!!

RagMan

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Re: Hi-Compression Piston
« Reply #19 on: November 27, 2007, 11:01:18 AM »
That would be a way to go, but with bikes you can seriously mess with ratios by changing the front and rear sprocket; works out a lot cheaper. My oversize front sprocket, stock rear makes for 65 mph all day.
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Jefferson County, WA

Peter

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Re: Hi-Compression Piston
« Reply #20 on: November 27, 2007, 12:29:36 PM »

The R E  seems to have plenty of raw torque to handle more gears.  If it had a still higher gear than the fifth one, or if the fifth one were made higher, then it would seem to have the torque to handle it just fine.  It wouldn't have to be that much higher to handle an additional ten miles per hour speed.  At a time like this I wish I knew what I'm trying to talk about!  But someone on the forum may have that sort of knowledge - hope - hope!!!

I bought my Bullet from somebody who had improved the exhaust system, put a 30mm Amal in and changed the sprocket to 18 teeth. Then the piston seized and he sold it to me. That's at more than 4000 miles. I rebuilt the top end with an alloy jug and high comp piston with one 2mm compression plate and it has been running fine with no oil consumption since then. It will cruise at 60-65mph all day long.

The short answer is: You overgear the stock Bullet, you are risking overheating and demise of your piston unless you ride it very carefully and don't torture it in too high a gear.

Peter
 

Sam

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Re: Hi-Compression Piston
« Reply #21 on: November 27, 2007, 04:34:38 PM »
More gears are good when the powerband is narrow; the idea is to keep the engine in it's happy zone. What passes for a powerband on an Enfield is pretty broad, I don't think more gears will do anything besides allow for more neutrals. The other reason for more gears is fashion; that's why HD has gone to a 6 speed overdrive on bikes that don't really need more than 2 speeds.

I'm sure the ratios in the 5-speed are available somewhere; for sure, in my shop manual and certainly elsewhere, I've definitely seen them. The 5 speed is more evenly spaced than the 4 speed, doesn't have the big hole in the middle.


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cyrusb

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Re: Hi-Compression Piston
« Reply #22 on: November 27, 2007, 08:38:16 PM »
When I read about possible hop up schemes for the RE my first reaction is to ask yourself"Why did I buy  this motorcycle?" Certainly not for its performance level. I bought mine because I love the "living antique" aspect of it. No other new bike that I know of can provide that.If I was looking for high performance, or just plain performance I would have picked another. Its more than just a bike its a"TIME MACHINE"

RagMan

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Re: Hi-Compression Piston
« Reply #23 on: November 27, 2007, 09:02:22 PM »
That is so true - I love the time machine aspect of the Bullet - it is a nice, easy ridden, safe feeling bike. I have tried some of the crotch rockets, and never felt comfortable on them. One, a Ninja, I felt very unsafe. Compared to the Sportster I have been riding, the Bullet is like a comfortable old chair.
aka Indiana Bulleteer.
''99 Classic Bullet. '05 Ural Tourist sidecar rig, converted to 2wd. '05 Harley Davidson Sportster.
Jefferson County, WA

GreenMachine

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Re: Hi-Compression Piston
« Reply #24 on: November 27, 2007, 09:17:55 PM »
Ragman has it right on the money...A Time Machine and if u have one, u know what that means...not about speed but pleasure of a time long gone...If u want more speed..purchase a second bike for that endeavor...
Oh Magoo you done it again

dewjantim

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Re: Hi-Compression Piston
« Reply #25 on: November 28, 2007, 12:17:31 AM »
Hey guys, know when auto racing first started? The first time two autos got together. Do you know when hot rodding was first invented? It was by the guy that got beat...... If you have to ask, you just don't understand......Dew.
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indian48

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Re: Hi-Compression Piston
« Reply #26 on: November 28, 2007, 12:59:29 AM »
Different strokes, Dew, different strokes!
If anything is worth doing, it is worth doing well

LJRead

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Re: Hi-Compression Piston
« Reply #27 on: November 28, 2007, 01:03:20 AM »
yeah Dew - it is like sailboat racing, some take out their killer instincts on the race course, some prefer to slowly drift around the pond.  And, like bikes, the racers burn up a lot of gear and money to replace it.  I understand Albert Einstein's friends bought him a boat in appreciation and he would drift out and go to sleep on it - now there was the smart one.

indian48

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Re: Hi-Compression Piston
« Reply #28 on: November 28, 2007, 01:13:27 AM »
I will attempt to clarify my comment on performance in another way. When the RE that we ride was designed, it was meant to meet certain performance criteria. As the design was handed over to manufacturing, and then on through the years with value engineering ( mostly a fancy word we corporate guys use for cost cutting by cutting corners), and with impact of poor quality in the Indian supply chain ( being an Indian in India, I am entitled to say that for sure!), and because of legislation due to emission and noise standards, the bike is delivering performance way under the design spec. My effort on performance, if I could, would be to get the bike to perform back to the original design spec in concept.
A separate but related point on emissions and noise control. RE has to do what it does to comply with the legislation, and that's fair enough. However, there are not many of us RE  riders around ( the Indian annual bike output is a few million and that of RE India is 35000), and even if all of our bikes had emissions the way they were in the fifties, it is not going to make any impact on a global scale to the warming issue. Likewise, if we rode responsibly, the little increase in db also will not be a big issue - for instance when I go on my very early morning rides, I push the bike to a place where it will not wake up the neighbors before I start it. With this background, even if it may be illegal for us to roll back the emission output and the db levels restrictions imposed on the bike, would that also be unethical? Or would we be  being poor citizens by doing so? I do not believe so, but I would like to hear what others feel.
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cyrusb

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Re: Hi-Compression Piston
« Reply #29 on: November 28, 2007, 03:23:39 PM »
Hey, it's just a personal choice. I'm sure in the end that some of us will have carbon fiber walkers.