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ok so I have a 2000 sporty 1200 evo. Nothing has been done to this bike proformance wise. Before I got it my step mom rode it and she had over reved the engine causing a gasket to start leaking with about 10k miles on it. It was fixed. After I got it I put drag pipes on it to make it noisier, and it did. Needles to say I was putting in a parking lot and all of the sudden I lost compression on the rear cyl. I had bent a pushrod. Got it home and tore it down to find the valve guide seal on that head was so bad that my valve stems were stained brown n black but the front head was not like that. Now my ole man shares I bent the push rod because I didn't rejet the carb. And it was caused by putting the drag pipes on it and their not being enough back pressure. Im told no that something bigger has gone wrong in the block but I've put it back together with stock pipes and so far so good. Does anyone know if putting drag pipes on my stock 1200cc 2000 sportster would cause the valve to hit the piston and inturn causing the pushrod to be bent? It was on the exhaust valve that did it but I was reading about back pressure and ppl. Are saying backpressure is a wise tale. If anyone can shed some light as to whats going on here it would be appreciated. Thanks in advance and God bless.
 

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Too lean, which equals too hot, in turn the valve sticks in the guide, quits moving, stays open and the piston runs right into it.
 

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None of this has anything to do with anyone's mum.
Perhaps the lack of an AFR gauge is missing due to some error?
 

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If you are insisting I know nothing that is fine with me.
If the essence or credence is to be baked dwn to what we know compared to others?
Then, none of us should ever participate here.?
My bragging point is 1.30 per cube for a street engine ..not too many people can match that for an old archaic V twin can they?
SOoooooo I don't know anything and can prove it.
but I do have an AFR ,meter on my bike.
back to the task
A lean mixture may have caused the above damage...... But i am inclined to say wrong guide material for aplication.
 

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Make me use my bullet?
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Wow! You guys took a lot of words to say what Autoworker already said in just a few. I guess offering good advice doesn't count unless you can be a conceited douche in the process. Go figure.
 

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The cognitive dispensary and the thrum of life mixed with innocuous theory have little to do with helping the OP problem!
Right?
If you would like to dive into the deeper things of the IC engine, I am more than happy to discuss them or all of it as I have room to grow.
As i know nothing and still can prove it.
Let's start a recip thread and we can all add oor divergences?
How can I prove it?
I was going to patent a new valve system and looked into a rotating valve assembly that would get rid of all sorts of dangerous crap with springs, keepers etc etc .
It would have been the utopia of a breathing machine with about three parts to make it all work!
TOO my embarrassment- it all has been done.!!
In fact, remember how chevy bragged about their V8 being the first to develop more than one to one hp per cube ?
A complete LIE!
LIE lie lie lie!
The WW2 AC industry had already done it.'
In fact, they had developed cylinders that would rotate to line up timed port marks, as the engine rotated,!
Freeking genius!
As we sit here and postulate the nuances of the antiquated archaic Harley engine, attempting to get the 1.25per cube or more out of 91 octane on the street,...
Time has simply passed us caveman by.!!
It seems electric and some other means are on the horizon for power and the petroleum-fueled recip is all but done.
The 30 % efficacies is just too far short of the goal line.
The old recip needs to be or get 80 or 90 percent to achieve any dedicated ardent enduement
from the new skinny jean man Bunn crowd.
Simple.
Period.
They have a zero for romancing the sound of a glorious single plane crank, much les the old V-twinn!
It is not going to happen without some major accomplishment.
Their lack of testosterone overrides any decision from a fortnight of years past to the next kingdom to come.
The big companies that make recip engines and parts used to be the new highs of principals of inventions, now, rather on the precipice of destruction.
 

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ok so I have a 2000 sporty 1200 evo. Nothing has been done to this bike proformance wise. Before I got it my step mom rode it and she had over reved the engine causing a gasket to start leaking with about 10k miles on it. It was fixed. After I got it I put drag pipes on it to make it noisier, and it did. Needles to say I was putting in a parking lot and all of the sudden I lost compression on the rear cyl. I had bent a pushrod. Got it home and tore it down to find the valve guide seal on that head was so bad that my valve stems were stained brown n black but the front head was not like that. Now my ole man shares I bent the push rod because I didn't rejet the carb. And it was caused by putting the drag pipes on it and their not being enough back pressure. Im told no that something bigger has gone wrong in the block but I've put it back together with stock pipes and so far so good. Does anyone know if putting drag pipes on my stock 1200cc 2000 sportster would cause the valve to hit the piston and inturn causing the pushrod to be bent? It was on the exhaust valve that did it but I was reading about back pressure and ppl. Are saying backpressure is a wise tale. If anyone can shed some light as to whats going on here it would be appreciated. Thanks in advance and God bless.
Drag pipes will not cause the piston to strike a valve.

Over revving will.
Poor valve guide fit will.
Weak valve springs will.

Bent valve stems from previous valve strikes will sometimes cause the valves to stick open. But that will also manifest as a weak cylinder do to low compression.

Pretty hard to over rev a motor with a rev limiter built in. But I suppose someone could have shifted to first at 50mh and dumped the clutch.

The bent push rod is a whole nother issue. The engine has to be mechanically out of time to bend a push rod. Or the rod is adjustable and someone lengthened it until it jacked a valve into a piston.

I think you need to get that motor opened up and see just what has gone wrong.
 

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Seriously.
because it is a Harley forum i can not know more words than types of wax? LOL
To the point, i bought a brand new iron head right after I got back from Nam, pretty soon .
not too far into its future onceineth awihest letting off the throttle, it would back fire like the proverbial HEll !!
To the point, They had installed steel valve guides in the iron head and it was not agreeing with the gas..and the guide would hang up the exhaust valve.
It never bent them, but the piston would tap them back in the direction they should have been going.
But there has been lots of bent valves since way back then...a learning curve for sure.
 

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Seriously.
because it is a Harley forum i can not know more words than types of wax? LOL
To the point, i bought a brand new iron head right after I got back from Nam, pretty soon .
not too far into its future onceineth awihest letting off the throttle, it would back fire like the proverbial HEll !!
To the point, They had installed steel valve guides in the iron head and it was not agreeing with the gas..and the guide would hang up the exhaust valve.
It never bent them, but the piston would tap them back in the direction they should have been going.
But there has been lots of bent valves since way back then...a learning curve for sure.
And what does any of that have to do with an Evo sporty bending push rods?
 

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Nothing.
unless there is the wrong guide or clearances in there..
As you said / I said,-his exhaust is not going to bend valves.
 

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You missed the point. Maybe I should have mentioned that Autoworker, Therm, Tall Terry, Uncle Salty and Troqed who else. All are geniuses in their own right concerning Harley motors. They know frames, wheels drive trains from the first Harley to the present day bikes. They can tell a member what will or won't work and why. I've read some of Therms posts giving intricate details of sizes, torques etc that gives me a headache halfway through, but to the amateur mechanics here it is fascinating reading. I could have said all that and then there would have been no misunderstanding of my short history lesson and it was off topic, but that is what we do here.

Sent from a guy whose mum is dead
You have me mixed up with someone else. Those other guys you mentioned have much more experience than I. I'm just a hack with a tool box, a beer and a good wife. 🍺
 

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Make me use my bullet?
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Seriously.
because it is a Harley forum i can not know more words than types of wax? LOL
To the point, i bought a brand new iron head right after I got back from Nam, pretty soon .
not too far into its future onceineth awihest letting off the throttle, it would back fire like the proverbial HEll !!
To the point, They had installed steel valve guides in the iron head and it was not agreeing with the gas..and the guide would hang up the exhaust valve.
It never bent them, but the piston would tap them back in the direction they should have been going.
But there has been lots of bent valves since way back then...a learning curve for sure.
You may want to work on formation of sentences and paragraphs and basic words like "to and "too" and "our" and "less" before you start trying to impress us with your "words". :rolleyes:
 
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I get paid to write .......SOoooo I will try to accommodate the audience herein.
I am sure most everyone can understand basic English? (without a lot of four-letter words ?)
Next will come the spell check nazzies.
 

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Make me use my bullet?
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I get paid to write .......SOoooo I will try to accommodate the audience herein.
I am sure most everyone can understand basic English? (without a lot of four-letter words ?)
Next will come the spell check nazzies.
Huh. I would have guessed you might get paid to NOT write, or talk.
 
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Well........your guess is so wrong .
Plus I have a deadline tonight....you all go argue about notin with yourselves.
If you want to be schoolmarms I am sure there is an effeminate allocation for you somewhere.
 
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