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loss of compression on rear cylinder...

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  #11  
Old 08-05-2018, 09:52 PM
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Originally Posted by djl
If you have the wants and funds, why not bore to 107? Machine work, new pistons and most importantly, head work is really all you need. The 222 cams should respond well to the compression increase. No need to bore the T/B unless you just want to. Replace the FP3 with the Power Vision, dyno tune and done. See how the exhaust responds to the upgrade; you can always change pipes.
looking to do just that since I'm already this far. already have the PV and don't really want to go into the can chest as the 222 has served me well in their presentation state. however...a cam change is not out of the picture if there is much more to gain in low end torque. I'm curious to know how much they they will respond to the head work and compression increase. any idea how much increase they can stand. will be sending the heads and cylinders out this week so I need to make some decisions in a day or so.
thanks
 
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Old 08-05-2018, 10:04 PM
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Originally Posted by DK Custom
Glad you found the problem. When you button her back up, add a External Breather System to your A/C, or get and A/C that already has an EBS, that way you won't get all the performance robbing hot, oily, oxygen depleted air into your combustion chambers, which is also causing that carbon build-up you saw.

LINK to info on EBS's.

LINK to Performance A/C's.

Feel free to come down and visit us...we're just down the 78 from you.
will do on the visit.
what EBS do you suggest for my AN big sucker.

thanks
 
  #13  
Old 08-06-2018, 12:00 AM
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Originally Posted by memphisharley
will do on the visit.
what EBS do you suggest for my AN big sucker.

thanks
Cool, we're there M-F, 9-5.

Any of the EBS's at this LINK will work with the AN BS.
 
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  #14  
Old 08-07-2018, 11:17 PM
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Originally Posted by roussfam
Gotta love adjustable push rods. Tried them once, pita, last three bikes pulled the rockers instead. Less trouble when all was said and done but that's just me.
are you tightening them good? have had several bikes with screw adjustable rocker arms, never had one of those come loose. curious how many TPI on your adjustables?, I have the S&S quickees are 32tpi, the finer threads the torque compounds more, have not had any come loose, checked them recently are good and tight.
 
  #15  
Old 08-12-2018, 05:26 AM
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I would not get all panicked about a pushrod getting lose, Or tight.
I would check the technique how the jam nut is snorked.
Use the one-handed squeeze method if you can (both wrenches in the palm squeezing them together
will truly tighten the lock nut dwn.)
In more years then you want to know I have not see this to be a problem. (coming lose)
Dont wory about it.
a non adj pushrod one is ideal, but a PIA for other work on the bike.
 
  #16  
Old 11-24-2021, 11:14 AM
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Originally Posted by memphisharley
was traveling on the highway running ~70 when the bike started slowing then just shut completely off so i coasted to the side of the road and start to restart her. bike was cranking but not firing. had just filled up not even a mile away. bike was getting fuel so i pulled the plugs to check them out as i just replaced them about 1k miles ago. reinstalled then and tried to restart. bike started but was only a sputter for a brief moment then it shut off. it would not restart. while cranking there was an odd sound from the rear cylinder as it didnt sound like the front. pulled the plugs and put my thumb over the front cylinder spark plug hole while cranking and the compression almost blew my thumb off. tried the same with the rear and i barely felt and pressure. i was about 200 miles from home and was with a few other riders and a truck with a trailer so I trailered the bike home. just pulled both cylinders but do not see what the issue is. I was going to go 107 kit this winter so looks like I will do this now. however, I have no idea what went wrong and would like to know before I put it back together. cylinders look great...pistons have carbon buildup but I don't think that would cause a loss of compression. could there be a hole in the piston under the carbon. what are some of the reasons for loss of cylinder compression.
bike is 2012 flhx with 18k.
any ideas what I should be looking for at this stage.
thanks
Hey,

I ran into the exact same issue with my 2018 CVO limited. I towed it to HD service and after a few days of investigation, service told me that my rear cylinder is low on compression and they are going to tear down the engine to find out why? I was wondering what things might cause this? mainly worried with the cost of repair and parts.
 
  #17  
Old 11-24-2021, 11:39 AM
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Originally Posted by alok_pandey
Hey,

I ran into the exact same issue with my 2018 CVO limited. I towed it to HD service and after a few days of investigation, service told me that my rear cylinder is low on compression and they are going to tear down the engine to find out why? I was wondering what things might cause this? mainly worried with the cost of repair and parts.
This thread is three years old. Several reasons for low compression but since you probably don't have adjustable pushrods, common reasons for low compression are the result of poor ring seal or a valve not closing.

Suggest you start another thread on you subject with as much information as you can provide about the bike.
 
  #18  
Old 11-25-2021, 07:51 PM
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I think the most common issue on the M8s with low mileage is a blown headgasket or possibly a broken head bolt.
 
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