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I just bought a set of K. B 10:50 -1 dome top pistons, (standard bore) for my 93 FXDWG.. I've had a few people tell me I may have to file the top ring a little for fitment.. I was wandering if anyone has actualy had to do this.. if so how did you do it..
thank you
Sandman.. Is.
 

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Ideally, the cylinder should be freshly honed straight and round with a torque plate and ring gaps checked with the torque plate. I set the ring gap on mine without the plate as the cylinders were sent away to be bored and honed. I ordered oversized rings so I could set the gap to ideal. I used a manual tool to file the gap, probably cost $75 now days. You could use a file but the tool makes it easier to avoid messing up a ring.

266864


Here are a couple of links to help you.


 

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Ideally, the cylinder should be freshly honed straight and round with a torque plate and ring gaps checked with the torque plate. I set the ring gap on mine without the plate as the cylinders were sent away to be bored and honed. I ordered oversized rings so I could set the gap to ideal. I used a manual tool to file the gap, probably cost $75 now days. You could use a file but the tool makes it easier to avoid messing up a ring.

View attachment 266864

Here are a couple of links to help you.


Ideally, the cylinder should be freshly honed straight and round with a torque plate and ring gaps checked with the torque plate. I set the ring gap on mine without the plate as the cylinders were sent away to be bored and honed. I ordered oversized rings so I could set the gap to ideal. I used a manual tool to file the gap, probably cost $75 now days. You could use a file but the tool makes it easier to avoid messing up a ring.

View attachment 266864

Here are a couple of links to help you.


uncle
Ideally, the cylinder should be freshly honed straight and round with a torque plate and ring gaps checked with the torque plate. I set the ring gap on mine without the plate as the cylinders were sent away to be bored and honed. I ordered oversized rings so I could set the gap to ideal. I used a manual tool to file the gap, probably cost $75 now days. You could use a file but the tool makes it easier to avoid messing up a ring.

View attachment 266864

Here are a couple of links to help you.


uncle Sally,thanks for the info it will help,the one thing I do have going for me are my cylinder walls are beautiful,(perfect cross hatching)..some body mentioned with this set up I could have hard starts,I believe I took care of that problem,when..(I was hoping it was just the starter hung up)..now my starter is equiped with direct drive..should make the starts a little easier.
 

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If you are talking about running a EV-13 cam with 10.5 to 1 compression, I'm not the guy to give advice. I never owned or worked on an Evo. But a quick glance at Big Boyz Evo Compression calculator, an EV-13 with a true 10.5 to 1 compression is going to yield around 210 PSI cold cranking compression at sea level. You might want to ask around again. I'm at 185 to 188 PSI cranking compression on my 95" Twin Cam and that's manageable with EFI but I wouldn't want to run it any higher.
 

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10.5-1 compression with an EV13 cam, is a recipe for problems 24/7/365.. it wont start easy, it will have spark knock, it will run hot,,and the power band will end around 4K rpm.. you will have to 9ver jet the carb (richen it) and retsrd the timing and advance curve,, all in a futile effort to make the parts work together,, they wont,,, the bike will under perform,,, basically, the op will be spending alot of money and time to build a turd.. just my opinion, what do i know?
 

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If you are talking about running a EV-13 cam with 10.5 to 1 compression, I'm not the guy to give advice. I never owned or worked on an Evo. But a quick glance at Big Boyz Evo Compression calculator, an EV-13 with a true 10.5 to 1 compression is going to yield around 210 PSI cold cranking compression at sea level. You might want to ask around again. I'm at 185 to 188 PSI cranking compression on my 95" Twin Cam and that's manageable with EFI but I wouldn't want to run it any higher.
10.5-1 compression with an EV13 cam, is a recipe for problems 24/7/365.. it wont start easy, it will have spark knock, it will run hot,,and the power band will end around 4K rpm.. you will have to 9ver jet the carb (richen it) and retsrd the timing and advance curve,, all in a futile effort to make the parts work together,, they wont,,, the bike will under perform,,, basically, the op will be spending alot of money and time to build a turd.. just my opinion, what do i know?
Tall Terry, what would you recommend for compression in order for me to keep my cam
10.5-1 compression with an EV13 cam, is a recipe for problems 24/7/365.. it wont start easy, it will have spark knock, it will run hot,,and the power band will end around 4K rpm.. you will have to 9ver jet the carb (richen it) and retsrd the timing and advance curve,, all in a futile effort to make the parts work together,, they wont,,, the bike will under perform,,, basically, the op will be spending alot of money and time to build a turd.. just my opinion, what do i know?
Tall Terry ,what would you recommend for compression,in order for me to still use my cam
 

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If you are talking about running a EV-13 cam with 10.5 to 1 compression, I'm not the guy to give advice. I never owned or worked on an Evo. But a quick glance at Big Boyz Evo Compression calculator, an EV-13 with a true 10.5 to 1 compression is going to yield around 210 PSI cold cranking compression at sea level. You might want to ask around again. I'm at 185 to 188 PSI cranking compression on my 95" Twin Cam and that's manageable with EFI but I wouldn't want to run it any higher.
inle salty ,what would you recommend for compression in order for me to still use the ev-13 cam
 

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Since the motor is in pieces, I would trade that 13 for an ev27 and not have to back spark (and power) out of it later to stop it from pinging.
 

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the ev13 was made for low compression,, so,, stock compression not over 9-1.. the 27 or 46 will really like the 10.5 comp... i like the 46 alot ive used dozens of that grind.. in fxr, dyna and softails.
 

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inle salty ,what would you recommend for compression in order for me to still use the ev-13 cam
If it were me, I'd ask some of the guys around here that know more than me. Two of them have given you their advice. I'm sure Therm and tall terry know Evo motors like the back of their hand.
 

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Pick your cam.Pick your pistons.Pick either first.Just match the other to the first pick.
 

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the ev13 was made for low compression,, so,, stock compression not over 9-1.. the 27 or 46 will really like the 10.5 comp... i like the 46 alot ive used dozens of that grind.. in fxr, dyna and softails.
I decided to keep the EV-13 cam and go with the Kieth black dome top ,I believe it's 8.75 (or close to that) don't remember the exact numbers.. it should still pull pretty decent
 

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I just bought a set of K. B 10:50 -1 dome top pistons, (standard bore) for my 93 FXDWG.. I've had a few people tell me I may have to file the top ring a little for fitment.. I was wandering if anyone has actualy had to do this.. if so how did you do it..
thank you
Sandman.. Is.
I decided to keep the EV-13 cam and go with the Kieth black dome top ,I believe it's 8.75 (or close to that) don't remember the exact numbers.. it should still pull pretty decent
Did I miss something? Didn't your first post say the KB pistons would yield 10.5:1 CR?

Please come back and tell us how this works out.
 

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Did I miss something? Didn't your first post say the KB pistons would yield 10.5:1 CR?

Please come back and tell us how this works out.
look up the international journal of automotive and mechanical engineering,I. e. Effect of compression ratio by differant piston head shapes on the perfomancs of motor cycle engines. it's about 12'pages long
 

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well, at least he made an acceptable choice,,, it will run good provided he jets the carb right, has a good pipe on it, and adjustable ignition,,,

personally, i would have tossed the ev13, went the 10.5-1 and stuck an ev46 in it,, to me,, that is what stock should have been..
 

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Did I miss something? Didn't your first post say the KB pistons would yield 10.5:1 CR?

Please come back and tell us how this works out.
I think charlie may have purchased a different set of pistons to lower the compression so he could run the EV-13 camshaft. Not sure but that's my take on it.

uncle Sally,thanks for the info it will help
uncle Sally??? OK guys, I am now Uncle Sally! Don't spell it wrong, OK?
 

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well, at least he made an acceptable choice,,, it will run good provided he jets the carb right, has a good pipe on it, and adjustable ignition,,,

personally, i would have tossed the ev13, went the 10.5-1 and stuck an ev46 in it,, to me,, that is what stock should have been..
Tall Terry, I would have preferd to keep the 10.5-1 also but do to finances unexpectedly getting tighter I had no choice but to go with my decision,I've got V&H staggered big long shots ,the carb work has been done,I've missed out on most of the season already and I just want to ride..
 
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