when doing a compression test


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quasi2008
Posts: 80
Joined: Fri Oct 05, 2018 12:18 pm
Location: morgantown wv
Motorcycle: 1982 GL1100I INTERSTATE

when doing a compression test

Post by quasi2008 » Sat Dec 08, 2018 5:13 pm



82 gl1100i, did my test on all 4 cylinders and they all read 105'ish. :( I thought well, I just threw away the price of the bike plus the cost of all the parts I replaced. bike runs good, starts right up, I asked myself why the low compression readings? THEN, I read on here where the throttle needs to be wide open to get a proper reading. imagine that! well did the tests all over again with the throttle wide open and all 4 holes read 170'ish. so I feel a little better now. I know I should have done the compression test before doing anything else, but just never really thought to do it. will be doing valve seals in the next few days.


man can't live on air alone!

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Aussie81Interstate
Posts: 1037
Joined: Thu Nov 27, 2014 2:34 am
Location: Penrith Australia
Motorcycle: 2001 GL1500F6C Valkyrie
1982 CX500 Turbo (Historic registration - finally)
1981 GL1100 Interstate (sold)
1988 GL1500 (sold)

Re: when doing a compression test

Post by Aussie81Interstate » Sat Dec 08, 2018 5:34 pm

Did you run the compression test on a cold engine or after it had warmed up - this will make a difference in the readings also.. Best off done with a warmed up motor.

Why do you need to replace the valve seals? is it belching out smoke and not going away??

Any history on the bike? mileage, maintenance etc.... why go through the process if you may not need to.... :)

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quasi2008
Posts: 80
Joined: Fri Oct 05, 2018 12:18 pm
Location: morgantown wv
Motorcycle: 1982 GL1100I INTERSTATE

Re: when doing a compression test

Post by quasi2008 » Sat Dec 08, 2018 5:46 pm

engine was warmed up. smoking on startup some, kept on center stand. has 72,000 miles on it. hadn't had much for maint done to it since 1988 near as I can tell. it sat for a while from what I can tell. bike was in somewhat sad shape when I got it, ran but not very well. pretty much ready for the road now. I do still need to adjust the air/fuel mixture. waiting on tool to get here.
man can't live on air alone!

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Aussie81Interstate
Posts: 1037
Joined: Thu Nov 27, 2014 2:34 am
Location: Penrith Australia
Motorcycle: 2001 GL1500F6C Valkyrie
1982 CX500 Turbo (Historic registration - finally)
1981 GL1100 Interstate (sold)
1988 GL1500 (sold)

Re: when doing a compression test

Post by Aussie81Interstate » Sat Dec 08, 2018 6:26 pm

I would ride it for a while - see if the smoke clears up - could be rings settling in again - do your valve adjustment as well - and change the oil if not already done with a new filter.

Most likely the smoke may go away if you are lucky.

Cheers

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quasi2008
Posts: 80
Joined: Fri Oct 05, 2018 12:18 pm
Location: morgantown wv
Motorcycle: 1982 GL1100I INTERSTATE

Re: when doing a compression test

Post by quasi2008 » Sat Dec 08, 2018 7:40 pm

I've went thru the bike from one end to the other, bearings, cables carbs, fluids, brakes & lines, belts and idlers and several other things. about all that is left is the valve seals. it's froze up in these parts so i'm not going to far. i'm retired and plan to do some "sightseeing" in 2019.
man can't live on air alone!

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Rednaxs60
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Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD
1995 GL1500 SE CDN Edition
2008 GL1800 (sold)
Ontario 1985 GL1200 LTD (sold)

Re: when doing a compression test

Post by Rednaxs60 » Sun Dec 09, 2018 11:21 am

You may want to consider doing a leak down test as well. This will indicate whether there are leaks with the valves and rings.

If you are going to do the valve seals, you may want to consider doing a lapping of the valves as well to clean the valves and valve seats, or take into a machine shop and have the shop give the valves/valve seats a minor skim and resurface the heads for install. The shop will also let you know if the valve guides are worn and need replacing, probably not, but never know.

Just had the heads on my '85 LTD done, exhaust valves were leaking like Niagara Falls. Going to do a leak down test before I start the engine so I will be using Fogging Oil in the cylinders to help seal the cold rings. This will give me an indication of the piston ring condition.

I'm retired as well and use this bike to tour on, and to keep the mind sharp and active. It has been a three year project to date and has served me well. Goes any place my friends and their new HDs will and has.

Thoughts to consider. Good luck with the bike and have a great time in 2019 touring on it.

Cheers
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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quasi2008
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Joined: Fri Oct 05, 2018 12:18 pm
Location: morgantown wv
Motorcycle: 1982 GL1100I INTERSTATE

Re: when doing a compression test

Post by quasi2008 » Sun Dec 09, 2018 12:24 pm

good advice, thanks.


man can't live on air alone!

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