Low compression and fouled plugs, Help! - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 12 (permalink) Old 05-19-2007, 02:48 PM Thread Starter
 
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Low compression and fouled plugs, Help!

My wife doesn't ride much any more so I took her vulcan out yesterday for its twice a month exercise run. After about ten miles it started losing power, sputtering and so forth. I'm thinking, ok, old gas, gummed up carbs. I get home and dump half a can of seafoam in the almost full tank, run it a bit and turn it off. Today I go out and try to start it. Still running rough. Now there's a small puddle of what looks, feels and smells like gas mixed with oil coming from the rear cylinder exhaust. After two minute run, rear exhaust pipe it warm but not hot. The front is too hot to touch. Things aren't looking good at this point. So next, I pull the rear plugs. They are fouled with oily gas. Compression test is next. Front is 125 lbs, rear only 95. The bike doesn't burn oil, there's been no exhaust smoke and no unnatural noises. I'm not sure what to check next. The bike is a 2003 with 6,000 miles. The only real mod that might make a difference is the addition of a Jardine exhaust about 1000 miles ago. No exhaust leaks.
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post #2 of 12 (permalink) Old 05-19-2007, 03:40 PM
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Could be a stuck flote.
Once the plugs foule it was all down hill from there.
Did you try cleaning the plugs and see what happens, or replace them.

Chad Falstad "Hawk"
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post #3 of 12 (permalink) Old 05-20-2007, 08:11 PM
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Chad, I'm looking at the same kind of fouled plugs on my rear cyl - oily and damp (front seems ok - just a terrible noise coming from the cyl...). A couple of questions:
1. How do you clean the plugs? Can they just be cleaned off with acetone?
2. Clymer's says the oily, damp thing is an indication that they're burning too hot (too rich?). Should I change the plugs to hotter-burning ones, or just adjust the fuel/air mix? And if the former, would iridiums be the ticket?
3. I haven't done a compression test - what size adapter are you guys using for the tester?

Thanks!

C
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post #4 of 12 (permalink) Old 05-20-2007, 08:46 PM
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Acetone or Carb cleaner, I have been known to use Emery cloth to cleen them also. Dont do that to a Platnum or Iuridium.
Check your gap on the plug after.
Yes Black plug is a sign of unburned fuel or oil, A hotter plug might help but if you have a problem might not fix just a bandade.

Chad Falstad "Hawk"
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post #5 of 12 (permalink) Old 05-20-2007, 09:00 PM
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http://www.gadgetjq.com/ctune.htm
I've never used the product in this link but it looks handy for a problem like yours. Cleaning the plug may help or you could go up 1 or 2 heat ranges and buy the cheapest plug wally world sells and use it for trouble shooting. See if the cyl starts firing if so run it for 15-20 minutes under load and then pull and check plug. If you buy a compression testor buy a screw in model for a more accurate reading and you don't have to have 3 hands too get a reading. There was a post in the last couple of weeks that gave the correct method of checking compression. If you are using a compression gauge of unknown accuracy (calibration) remember that you are looking for a close balance between cylinders. I would run at least 2 tests and average them. Make sure your battery has a full charge before doing the test.

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post #6 of 12 (permalink) Old 05-20-2007, 09:22 PM
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Thanks, folks. I have a compression tester, but none of the adapters is sized to fit our plugs. Looks like ours are 11 or 12 mm? Can anyone confirm that? I think I'm looking at a complete teardown now, so I realize anything at the point is just a bandaid... blech.

C
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post #7 of 12 (permalink) Old 05-20-2007, 09:42 PM
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12mm

Rckmtn
Dennis Huff
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Jardine 2 into 2
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post #8 of 12 (permalink) Old 05-21-2007, 07:02 AM
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Quote:
Originally Posted by rckmtn View Post
12mm
Thanks, Dennis.

C
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post #9 of 12 (permalink) Old 05-25-2007, 05:30 PM
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Y'all remember when you do a compression test to hold the throttle wide open. Also remove all your plug wires!

Fergy
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post #10 of 12 (permalink) Old 05-25-2007, 06:44 PM
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Quote:
Originally Posted by fergy View Post
Y'all remember when you do a compression test to hold the throttle wide open. Also remove all your plug wires!
And all the plugs in the non testing cylinder.

Jon

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