free website stats program Compression check | Harley Davidson Forums

Compression check

D

dd1228

Active Member
I have reason to believe I have a problem with my front cylinder on my 2002 FLHTC with 72000 miles on it. Where can I get a compression guage and what figures am I looking for?
 
Screw on type compression guage from Harbor Freight is good value and is easiest to use...the push on type are hard to keep down on 150 PSI trying to escape. What you are looking for is 145-155 PSI with balance between front and rear.

May also want to pull the headlight fuse and ground the center spark plug contact to metal so the coil insulation does not breakdown due to HV arcing. May want to jumper the battery with car battery (do not have it running)...so plenty of juice is available for the battery to spin up the starter.
 
If you can find an aircraft mechanic with a diffrerentail type copression tester you can get an idea if it's rings or valve problems with the jug. May have to take and old spark plug and make up the addapter.
 
Thanks for all the replies, this sure is a great forum. I'm getting alot of noise from the front cyl area like tappets, but it isn't tappets cause I had the rocker box cover off and checked everything. Adjusted the push rods numerous times and replaced the lifters. Still the same old noise. I had a mech listen to it and he said I should check compression. So I'll try it. New cam chain tensioner shoes and cam bearings too. The bike seeems to run fine, but the noisy engine is driving me nutso. Some friends said to just turn the radio up, and don't worry about it...
 
My motor makes a lot of noise too. It was real bad when i first got it and it only had 2200 miles on it. Synthetic oil helped a little, but the screamin' eagle mufflers for off road use only fixed it completely. Now all i can hear is the sweet sound of thunder.
 
dd1228 said:
Thanks for all the replies, this sure is a great forum. I'm getting alot of noise from the front cyl area like tappets, but it isn't tappets cause I had the rocker box cover off and checked everything. Adjusted the push rods numerous times and replaced the lifters. Still the same old noise. I had a mech listen to it and he said I should check compression. So I'll try it. New cam chain tensioner shoes and cam bearings too. The bike seeems to run fine, but the noisy engine is driving me nutso. Some friends said to just turn the radio up, and don't worry about it...
Click to expand...
*************************************
Have you checked the oil pressure with a manual gauge? IF low on pressure It will make noise at Idle.. Has the pump been replaced properly ? ck pressure!

Just ONE MORE reply..... HOW does your bike sound DIFFERENT from the other HD's you ride with?

A lot of times New riders think it is ONLY their bike when The Old saying Fits..... "they all do it"

signed....BUBBIE
 
dd1228 said:
Thanks for all the replies, this sure is a great forum. I'm getting alot of noise from the front cyl area like tappets, but it isn't tappets cause I had the rocker box cover off and checked everything. Adjusted the push rods numerous times and replaced the lifters. Still the same old noise. I had a mech listen to it and he said I should check compression. So I'll try it. New cam chain tensioner shoes and cam bearings too. The bike seeems to run fine, but the noisy engine is driving me nutso. Some friends said to just turn the radio up, and don't worry about it...
Click to expand...

What cam did you put in the bike?
Cams that have a lot of torque typically from the git-go are noisier due to the ramps on the cam and quick closing intakes.

You are on the right track with a compression check, also would consider doing a leak down it will help ease the mind.

What size motor, what type of piston (flat top) or domed, what cam, and any headwork?

you can get an idea of the compression you should be at with this information by going to:

bigboyz website and go to calculators
 
You must log in or register to reply here.
Back
Top