Compression High
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Road Warrior
Joined: Sep 2007
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Compression High
I did a compression test in my 2003 RK. I took it cold cuz I was bored and didn't want to warm the bike up cuz I cant take it for a ride. 0 deg. F. up here today. I started the bike up on each cylinder with a digital compression guage threaded in. At idle for five sec it was 120. Blipped the throttle and brought the revs up to 2000 and it read 173 in both lungs. The motor has 19k miles (31k km). I would think it is good.
Randy
Randy
Road Warrior
Joined: Nov 2014
Posts: 1,962
Likes: 140
From: NY
FYI,any time you see compression spec stated by a mfg its for doing comp test on starter only with both plugs out and comp tester in 1 cyl at a time and not with the motor running @ idle or reving up too.
So the compression #'s you got with the motor running should not be compared to compression spec for a non running motor which are 2 diff situations.
You have to do the comp test like i rec (plugs out & using stater only) to get a proper accurate reading.
Scott
So the compression #'s you got with the motor running should not be compared to compression spec for a non running motor which are 2 diff situations.
You have to do the comp test like i rec (plugs out & using stater only) to get a proper accurate reading.
Scott
Last edited by wscott; Apr 3, 2016 at 04:08 PM.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
DO NOT DO THAT YOU MAY BLOW THE IGNITION !
compression test is done with a warm motor ( so the rings are sealed)
the throttle wide open and the motor can be turned by hand- have the test in one hole and the other open.
running an ignition system without a working grounded plug can blow the coil, this is even more important with late models where the ignition resistance is calculated by the ECM- "ion sense"
mike
compression test is done with a warm motor ( so the rings are sealed)
the throttle wide open and the motor can be turned by hand- have the test in one hole and the other open.
running an ignition system without a working grounded plug can blow the coil, this is even more important with late models where the ignition resistance is calculated by the ECM- "ion sense"
mike
Last edited by mkguitar; Apr 3, 2016 at 04:36 PM.
Road Warrior
Joined: Nov 2014
Posts: 1,962
Likes: 140
From: NY
DO NOT DO THAT YOU MAY BLOW THE IGNITION !
compression test is done with a warm motor ( so the rings are sealed)
the throttle wide open and the motor can be turned by hand- have the test in one hole and the other open.
running an ignition system without a working grounded plug can blow the coil, this is even more important with late models where the ignition resistance is calculated by the ECM- "ion sense"
mike
compression test is done with a warm motor ( so the rings are sealed)
the throttle wide open and the motor can be turned by hand- have the test in one hole and the other open.
running an ignition system without a working grounded plug can blow the coil, this is even more important with late models where the ignition resistance is calculated by the ECM- "ion sense"
mike
" running an ignition system without a working grounded plug can blow the coil, this is even more important with late models where the ignition resistance is calculated by the ECM- "ion sense"
MIKE,no disrespect intended but you need to get your facts right because your incorrect when it comes to my 09 flhtcu's fact srvc manual that as far as i am aware of is the same when it comes to removing the plug wires for newer bikes then my 09 too.
I say that for 3 reasons.
1) It's important to me to when possible to ensure proper information & or facts are being posted here.
2) Is my 1st hand esp doing it that way (plug wires removed from plugs like i rec) on all newer bikes inc my 2009 HD (and for that matter cars too) with never an issue.
3) But most importantly Is the fact my 09 hd factory srvc manual states all you do when doing comp test is to remove the plug wires & plugs and thats it!
HD srvc man states nothing else to do electrically other then to place comp tester in a cyl to do the test running motor on starter 5-7 comp cycles w-throttle blade open (allowing max air intake) and nothing else like placing plugs in plug wires and grounding them to heads to complete the circut or you will blow ign like your implying is the case which isnt the case (not true) when you read HD's instrctions /comp test procedure.
See below directly from my 2009 HD srvc maanul stating proper comp test procedure with doing nothing special with respect to plug wires after you remove them other then common sence keeping them aside so they dont zap you when doing test and also making sure they dont fire/spark on anything that could ignite or cause damage too.
Like i said,i have been doing comp tests on these bikes just like hd fact srvc man states to do without ever having any ign issues like you said.
See attached so you can see the proper/complete compression test procedure per Section 3:8 / pg3-17 of HD's fact srvc man for my 09 flhtcu w-96" motor that backs up what i stated.
Like i have stated here before,i have over 4+ decades wrenching bike/cars etc and only post what i know is the case from doing it mult times 1st hand and in this case have the HD fact srvc manual backing up what i said too .
So keep that in mind next time compression testing comes up here in future threads.
Happy motoring.
Scott
===============================================
Section 3:8 pg3-17 of HD's fact srv'c man for my 09 flhtcu w-96" motor..
COMPRESSION TEST
HD-33223-1
CYLINDER COMPRESSION GAUGE
Satisfactory engine performance depends upon a mechanically sound engine. In many cases, unsatisfactory performance is caused by combustion chamber leakage. A compression test can help determine the source of cylinder leakage. Use CYLŹINDER COMPRESSION GAUGE (Part No. HD-33223-1).
A proper compression test should be performed with the engine at normal operating temperature when possible.
1. Disconnect spark plug wires, clean around plug base and remove plugs.
2. Remove air cleaner. See 4.4 AIR CLEANER ASSEMBLY.
3. Connect compression tester to front cylinder per manufacŹturer's instructions.
4. Make sure transmission is in neutral. With throttle body butterfly plate in wide open position, crank engine continu-ously through 5 to 7 full compression strokes.
5. Note gauge readings at the end of the first and last comŹpression strokes. Record test results.
6. Repeat compression test on rear cylinder.
7. If the final readings are 125 PSI (862 kPa) or more, and if the final readings do not indicate more than a 10% variŹance between cylinders, compression is considered normal. If compression does not meet specifications, refer to Table 3-25.
8. Inject approximately 1/2 oz. (15 ml) engine oil into each cylinder and repeat the compression tests on both cylinders.
Readings that are considerably higher during the second test indicate worn piston rings.
NOTE
After installing spark plugs, be sure that throttle plate is in the closed position before starting the engine.
Table 3-25. Compression Test Results
I DIAGNOSIS | TEST RESULTS
Ring trouble
Compression low on first stroke, tends to build up on the following strokes, but does not reach normal. Improves considerably when oil is added to cylinder.
Valve trouble Compression low on first stroke, does not build up much on following strokes. Does not improve considerably with the addition of oil. Check for correct push rod length.
Head gasket leak
Same reaction as valve trouble.
Last edited by wscott; Apr 3, 2016 at 10:41 PM.
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Seasoned HDF Member
Joined: Jan 2006
Posts: 11,471
Likes: 2,998
From: Charleston, SC
==================================
" running an ignition system without a working grounded plug can blow the coil, this is even more important with late models where the ignition resistance is calculated by the ECM- "ion sense"
MIKE,no disrespect intended but you need to get your facts right because your incorrect when it comes to my 09 flhtcu's fact srvc manual that as far as i am aware of is the same when it comes to removing the plug wires for newer bikes then my 09 too.
I say that for 3 reasons.
1) It's important to me to when possible to ensure proper information & or facts are being posted here.
2) Is my 1st hand esp doing it that way (plug wires removed from plugs like i rec) on all newer bikes inc my 2009 HD (and for that matter cars too) with never an issue.
3) But most importantly Is the fact my 09 hd factory srvc manual states all you do when doing comp test is to remove the plug wires & plugs and thats it!
HD srvc man states nothing else to do electrically other then to place comp tester in a cyl to do the test running motor on starter 5-7 comp cycles w-throttle blade open (allowing max air intake) and nothing else like placing plugs in plug wires and grounding them to heads to complete the circut or you will blow ign like your implying is the case which isnt the case (not true) when you read HD's instrctions /comp test procedure.
See below directly from my 2009 HD srvc maanul stating proper comp test procedure with doing nothing special with respect to plug wires after you remove them other then common sence keeping them aside so they dont zap you when doing test and also making sure they dont fire/spark on anything that could ignite or cause damage too.
Like i said,i have been doing comp tests on these bikes just like hd fact srvc man states to do without ever having any ign issues like you said.
See attached so you can see the proper/complete compression test procedure per Section 3:8 / pg3-17 of HD's fact srvc man for my 09 flhtcu w-96" motor that backs up what i stated.
Like i have stated here before,i have over 4+ decades wrenching bike/cars etc and only post what i know is the case from doing it mult times 1st hand and in this case have the HD fact srvc manual backing up what i said too .
So keep that in mind next time compression testing comes up here in future threads.
Happy motoring.
Scott
===============================================
Section 3:8 pg3-17 of HD's fact srv'c man for my 09 flhtcu w-96" motor..
COMPRESSION TEST
HD-33223-1
CYLINDER COMPRESSION GAUGE
Satisfactory engine performance depends upon a mechanically sound engine. In many cases, unsatisfactory performance is caused by combustion chamber leakage. A compression test can help determine the source of cylinder leakage. Use CYLŹINDER COMPRESSION GAUGE (Part No. HD-33223-1).
A proper compression test should be performed with the engine at normal operating temperature when possible.
1. Disconnect spark plug wires, clean around plug base and remove plugs.
2. Remove air cleaner. See 4.4 AIR CLEANER ASSEMBLY.
3. Connect compression tester to front cylinder per manufacŹturer's instructions.
4. Make sure transmission is in neutral. With throttle body butterfly plate in wide open position, crank engine continu-ously through 5 to 7 full compression strokes.
5. Note gauge readings at the end of the first and last comŹpression strokes. Record test results.
6. Repeat compression test on rear cylinder.
7. If the final readings are 125 PSI (862 kPa) or more, and if the final readings do not indicate more than a 10% variŹance between cylinders, compression is considered normal. If compression does not meet specifications, refer to Table 3-25.
8. Inject approximately 1/2 oz. (15 ml) engine oil into each cylinder and repeat the compression tests on both cylinders.
Readings that are considerably higher during the second test indicate worn piston rings.
NOTE
After installing spark plugs, be sure that throttle plate is in the closed position before starting the engine.
Table 3-25. Compression Test Results
I DIAGNOSIS | TEST RESULTS
Ring trouble
Compression low on first stroke, tends to build up on the following strokes, but does not reach normal. Improves considerably when oil is added to cylinder.
Valve trouble Compression low on first stroke, does not build up much on following strokes. Does not improve considerably with the addition of oil. Check for correct push rod length.
Head gasket leak
Same reaction as valve trouble.
" running an ignition system without a working grounded plug can blow the coil, this is even more important with late models where the ignition resistance is calculated by the ECM- "ion sense"
MIKE,no disrespect intended but you need to get your facts right because your incorrect when it comes to my 09 flhtcu's fact srvc manual that as far as i am aware of is the same when it comes to removing the plug wires for newer bikes then my 09 too.
I say that for 3 reasons.
1) It's important to me to when possible to ensure proper information & or facts are being posted here.
2) Is my 1st hand esp doing it that way (plug wires removed from plugs like i rec) on all newer bikes inc my 2009 HD (and for that matter cars too) with never an issue.
3) But most importantly Is the fact my 09 hd factory srvc manual states all you do when doing comp test is to remove the plug wires & plugs and thats it!
HD srvc man states nothing else to do electrically other then to place comp tester in a cyl to do the test running motor on starter 5-7 comp cycles w-throttle blade open (allowing max air intake) and nothing else like placing plugs in plug wires and grounding them to heads to complete the circut or you will blow ign like your implying is the case which isnt the case (not true) when you read HD's instrctions /comp test procedure.
See below directly from my 2009 HD srvc maanul stating proper comp test procedure with doing nothing special with respect to plug wires after you remove them other then common sence keeping them aside so they dont zap you when doing test and also making sure they dont fire/spark on anything that could ignite or cause damage too.
Like i said,i have been doing comp tests on these bikes just like hd fact srvc man states to do without ever having any ign issues like you said.
See attached so you can see the proper/complete compression test procedure per Section 3:8 / pg3-17 of HD's fact srvc man for my 09 flhtcu w-96" motor that backs up what i stated.
Like i have stated here before,i have over 4+ decades wrenching bike/cars etc and only post what i know is the case from doing it mult times 1st hand and in this case have the HD fact srvc manual backing up what i said too .
So keep that in mind next time compression testing comes up here in future threads.
Happy motoring.
Scott
===============================================
Section 3:8 pg3-17 of HD's fact srv'c man for my 09 flhtcu w-96" motor..
COMPRESSION TEST
HD-33223-1
CYLINDER COMPRESSION GAUGE
Satisfactory engine performance depends upon a mechanically sound engine. In many cases, unsatisfactory performance is caused by combustion chamber leakage. A compression test can help determine the source of cylinder leakage. Use CYLŹINDER COMPRESSION GAUGE (Part No. HD-33223-1).
A proper compression test should be performed with the engine at normal operating temperature when possible.
1. Disconnect spark plug wires, clean around plug base and remove plugs.
2. Remove air cleaner. See 4.4 AIR CLEANER ASSEMBLY.
3. Connect compression tester to front cylinder per manufacŹturer's instructions.
4. Make sure transmission is in neutral. With throttle body butterfly plate in wide open position, crank engine continu-ously through 5 to 7 full compression strokes.
5. Note gauge readings at the end of the first and last comŹpression strokes. Record test results.
6. Repeat compression test on rear cylinder.
7. If the final readings are 125 PSI (862 kPa) or more, and if the final readings do not indicate more than a 10% variŹance between cylinders, compression is considered normal. If compression does not meet specifications, refer to Table 3-25.
8. Inject approximately 1/2 oz. (15 ml) engine oil into each cylinder and repeat the compression tests on both cylinders.
Readings that are considerably higher during the second test indicate worn piston rings.
NOTE
After installing spark plugs, be sure that throttle plate is in the closed position before starting the engine.
Table 3-25. Compression Test Results
I DIAGNOSIS | TEST RESULTS
Ring trouble
Compression low on first stroke, tends to build up on the following strokes, but does not reach normal. Improves considerably when oil is added to cylinder.
Valve trouble Compression low on first stroke, does not build up much on following strokes. Does not improve considerably with the addition of oil. Check for correct push rod length.
Head gasket leak
Same reaction as valve trouble.
If you want to make a point, make it short and to the point. Also, loose the resume. You put in it in every post and it adds nothing.
Just my opinion.
Last edited by lp; Apr 4, 2016 at 06:29 AM.
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