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08-07-2016, 08:27 PM, (This post was last modified: 08-07-2016, 08:28 PM by Crispy.)
Compression HIGHER than spec on on front cylinder: carbon deposits?
I took a compression measurement the other day because I'm thinking about doing the valve adjustment soon and synchronizing the carbs because my 650 hasn't been running great (hesitating, stalled a couple of times when taking off with a cold engine). I read 180 psi and 170 psi on the front and back cylinders respectively. 170 is the spec according to the manual, and it says to check for carbon deposits on the valves if it reads higher than that. Has anyone dealt with this before? Too much compression definitely doesn't sound like a symptom of loose valves...

I make lots of short trips on the bike because it's my daily driver and I have a 5 mile commute each way, so there are a lot of miles on the engine with it relatively cold. I've also been known to overfill the oil, which I could see gumming things up if it gets into the air box through the crankcase ventilation system...

I really don't want to take apart my cylinder heads. I've read about folks using a sea foam product sprayed directly into the air induction system to clean carbon, I want to try that first, has anyone here ever done that?
09-24-2016, 02:18 AM,
RE: Compression HIGHER than spec on on front cylinder: carbon deposits?
High compression.. interesting.

Seafoam is great for removing carbon. Air induction or added to fuel. Either way will pass through intake valve, cylinders, and exhaust valves. I've heard of people saying a double dose can be used safely in the fuel. I personally have used it in my fuel several times, and once in the crankcase briefly.. Going to dose it again here soon as I have some excessive carbon buildup from using premium fuel for an extended period of time.
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