103 Engine compression help
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3rd Gear
Joined: Aug 2014
Posts: 7
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From: Earth
I have compression release valves on the 103 engine correct? Do they need to be disabled by a fuse pull?
Before I go any further with testing the compression let me ask if I'm missing a step. So far I have first heated the engine to operating temps. Then screwed in the compression test hose. Held the throttle wide open and turn the engine over until the needle stopped moving. 6 or 7 cranks. Both cylinders were about 5 to 6 psi apart. One a little over 120 psi the other under 120.
Side note, the spark plugs were "ALL" black with soot. Not wet or shiny black but flat black. Is that a symptom of blow-by?
the calculator # I'll try them next.
Before I go any further with testing the compression let me ask if I'm missing a step. So far I have first heated the engine to operating temps. Then screwed in the compression test hose. Held the throttle wide open and turn the engine over until the needle stopped moving. 6 or 7 cranks. Both cylinders were about 5 to 6 psi apart. One a little over 120 psi the other under 120.
Side note, the spark plugs were "ALL" black with soot. Not wet or shiny black but flat black. Is that a symptom of blow-by?
the calculator # I'll try them next.
HDF Community Team
Joined: Jun 2006
Posts: 12,784
Likes: 2,613
From: san antonio
Remove the system relay from fuse block to disable ACR. IIRC, the system relay is #11 in fuse block location. The procedure is outlined in the service manual; get one.
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3rd Gear
Joined: Aug 2014
Posts: 7
Likes: 0
From: Earth
All this info I am asking for is to help me check on the condition of a used bike I'm looking into buying. I want to move up from a Sportster to something bigger that will carry two. Checking the compression is a way for me to get an idea if the bike has any hidden issues. So no I don't have a manual yet. "If" I get one of the bikes I considering then I will buy one for that particular model. Not all the bikes I'm checking out have the same engine.
Anyways Thank you to all who gave me helpful advice
Anyways Thank you to all who gave me helpful advice
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