Compression Test

I finally have been able to get outside and do a compression test on my Road Glide. The reason that I figured that I would do another is that I saw some oil on my plug that that I wasn't just too happy with seeing. Not saying that there is anything wrong, just wanted to make sure that all was OK. My results were 175psi on the front and 177 on the rear and that was with a battery that has been sitting for a couple of weeks now. I put it on the charger and then I am going to go back out and do it again and see if I get a better reading from a fresh charged battery!

WOW! Is my battery low. I should get a better reading once that thing is fully charged.

What year is your bike? I would think that PSI and the slight difference between the 2 cylinders would be more then acceptable.

What is the acceptable PSI for your bike? I would think anything over 100 PSI is good.

Wow! sounds well within specs for percentage of difference between cylinders,thats for sure! Was that warm engine or cold and dry cylinders? Sounds like it would be hard to be better! Few more cranking RPMs with a full battery and you might see 10% more,195-200 maybe. What does the manual say for compression range specifications?

Keep in mind that my engine is not stock. I have upgraded it to a 98 CI with head work. check out my thread, 88-98 CI Upgrade thread if you are interested in what it is that I did. I am not concerned about the 2 psi difference, you can't get better than that really.

RG, yes, I believe that I should be closer to that 195-200 psi range and yes, this was cold cranking psi.

Are ya supposed to do it with a warmed up engine? or doesn't it matter? I did it both ways on mine and got a little more with a hot engine. They say you should also watch the gauge and see what the pressure is on the first revolution. That may say somethin about the rings.

Never checked it I was in nice warm florida .dont know if derek checked it after they tuned it.it will get higher with a full batt .and just crank it till you get a max reading on gauge.that was ten seconds worth of cranking psi. 2 psi difference is very good .thats a nice motor.makes good power for a peanut cam.im impressed. Good job Johnny on the build.2 psi differences I dont think you have to worry about ring seal issuies .lol

I plugged the friggen battery in after I talked to you on the phone last night and it still wasn't charged when I left for the night. It is finally charged and I will get it taken care of when Hot Rider is done with her stuff tonight. That battery was really worn down that is for sure. I will make sure to let you know what is happening.

I am pretty sure that Derek didn't do a compression check on it before he tuned it. I know that I was going to ask him to do it but I dropped the ball and it never got done because I didn't specify that I wanted it done. Oh well, such as life Shiit Happens. Besides, I am not doing this compression test because I have major concerns about my engine. Yes, there was something that alarmed me at first that prompted me to do this but what I have seen so far, my worries were for nothing. As Paul mentioned, 2psi difference might as well be considered perfect..

Yep,Deka ,Big Crank and a couple other names,if it has the number ETX30L it is an East Penn/Deka battery and ETX30L is the one to fit your bagger,Picked up a Deka this spring for close to $100 less than the Genuine HD and that was delivered to my door...

175 & 177lbs is damn good for a weak battery,ring seal isn't an issue...fully charged I'd bet you're around 195lbs....You had your heads done and chambers set so you can go to Big Boyz and punch in your engine size,cam and chamber volume and it'll give you a pretty good idea what your build pressure should be

I am not getting any other battery other than an HD. I was playing around with my bike and not having it on the tender so I am not worried about my battery. I agree, I should have much better with a fresh battery!!

Extra $100 for a black casing and a HD logosounds reasonable