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80 in. EVO compression

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Old Sep 14, 2013 | 09:13 PM
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Question 80 in. EVO compression

I had a 1994 Electra glide with the 80 cu. in. EVO engine and had it rebuilt at 61000 miles. Made it to 101000 miles and the had a factory re manufactured engine installed. I ran compression tests on both engines several times during the 4 1/2 years I had the bike. Every test was made with a warm engine with the throttle held open and each test resulted in 145 to 150 psi in both front and rear cylinders. Very consistent with both engines. Both engines were stock except for having the Stage I upgrade. AC, Mufflers and re jetted carb. I now have a 1998 Road king with the 80 cu. in. with the Stage I upgrade with 44000 miles that I bought a month ago. I did a compression test 3 times now and the results are 170 psi in front and rear cylinders. Bike really runs great after I re jetted the carb. I know nothing about what might have been done to the engine previously.
My question is--- Is the increased psi compression on the Road King an indicator of possible engine work upgrades or is there a factory difference somewhere between the 1994 and 1998 stock 80 cu. in EVO engines. The 98 Road King weighs a little less than the Electra Glide, but from about 2800 rpm on up it pulls so much harder and faster than the Electra Glide ever thought about doing.. I'd like to know the cause of the difference in psi, but don't want to pull it apart to see what makes the difference.
Any ideas will be appreciated.............. Thanks.......... buckhorns
 
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Old Sep 14, 2013 | 09:21 PM
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hey Buck,

a quick and possibly accurate test is to grab a flathead and pop open one of your pushrod covers to see if ya gots collapsible or ajdustable rods.
it's guaranteed to work 80% of the time.
 
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Old Sep 14, 2013 | 09:42 PM
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Hey TV
Will check push rods in the morning. What if they are stock ?????

Was there any difference in cams between the 94 and 98 EVO engine. Maybe between different model bikes. ???????????????
 
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Old Sep 14, 2013 | 09:53 PM
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Stock 80" in 1998 is still at 8.5-1 compression, your engine is around 9.0-1 with a compression building cam like a EV13 or EV27 for 170, someone has put some giddy up in it
 
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Old Sep 14, 2013 | 09:57 PM
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Know it All.
Lol
 
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Old Sep 14, 2013 | 10:10 PM
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150 PSI is the expected normal for a stock motor (8.5:1 compression ratio and "N" cam). I suspect yours has had some work done.
 
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Old Sep 15, 2013 | 09:44 AM
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:
Originally Posted by Tee&Vee
Know it All.
Lol



It takes mistakes to know this stuff!
 
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Old Sep 15, 2013 | 12:35 PM
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Checked push rods this morning and they appear to be stock. Not adjustable. My biggest concern is that if the cam has been changed, did they change the inner cam bearing too. ?????????????????
77 Bagger and Uncle G, thanks for the input. Guess I'll put some miles on it. ( Run it and Watch it) If it keeps running as it is and the compression psi remain the same, I'll assume some work has been done to it and I will have saved some money and will be happy as He!!
 
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Old Sep 15, 2013 | 02:04 PM
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exactly. She's running, why bother. my $0.02, the po had the base gasket leak and bought a James top end kit then decided to do the torrington and cam swap and added a drop-in cam. Rockers off, the engine apart why buy new rods?
 
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Old Sep 15, 2013 | 06:26 PM
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My stock 80 incher had 150 psi on both cylinders. I installed JE 9.5-1 pistons and it went to 200 psi on each cylinder. Someone has worked on it. Kinda surprised it doesn't have adjustable push rods though. If it's running good, I'd just ride it.
 
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