I could use your 2 cents right about now... - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 35 (permalink) Old 01-13-2017, 03:14 PM Thread Starter
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I could use your 2 cents right about now...

I have an 03 with 36K miles. Yesterday I was on my way home when I noticed the bike was running cold (165 down from 176). 10 minutes later i was down to 1 cylinder with the second coming on during wide open throttle only. Two blocks from home i could see white smoke (maybe it was blue/white hard to tell with a tinted visor) blowing out the exhaust.

Got home and found the following:
-oil on the front cylinder spark plug
-no oil on the rear cylinder spark plug
-oil seeping from the bottom of the exhaust pipe where the exhaust connects to the head (front cylinder)
-no coolant in the oil
-no oil in the coolant
-oil seeping out of the slip-on pipe
-oil level still between max/min lines

I am planning to do a leak-down test this weekend but would appreciate any other ideas on what could be causing this.

Fingers crossed I don't need a full rebuild
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post #2 of 35 (permalink) Old 01-14-2017, 12:43 AM
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How was the coolant level?
Your temp will drop when water gets into the cylinder. This doesn't have to be a lot either. Water vapour will also deter ignition. As revs increase, combustion can be achieved due to the water / fuel ratio supporting ignition.
Start the bike up and after 30 seconds touch a damp rag to each of the headers to see which cylinder is not firing. I'm guessing its the front. I would say that what you think is oil may well be a mix of coolant / fuel and carbon. Once the bad one is located you will have some work to do. Hopefully it is coolant and not oil. If it is coolant there are a couple of likely culprits. Head gasket or cylinder liner.
Has your bike been ported?
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post #3 of 35 (permalink) Old 01-14-2017, 12:54 AM Thread Starter
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Coolant level is between the min and max lines. It has been raining a lot the past week and the RC is my daily so water has gotten everywhere. I don't think it has been ported however I am the third owner (purchased with 6.5k miles).

"Once the bad one is located you will have some work to do." Can you elaborate?
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post #4 of 35 (permalink) Old 01-14-2017, 01:08 AM
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Don't check the bottle. Check under the cap on the radiator.
Work...replace head / gasket or worse...cylinder liner / case.

Last edited by Way2Slooow; 01-14-2017 at 01:38 AM.
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post #5 of 35 (permalink) Old 01-16-2017, 06:44 PM Thread Starter
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update:
-rear cylinder holds 165psi (not bad for 14 years/36k miles)
-front cylinder barely holds 120psi

The front valves never fully close (hooked up an air line to the cylinder via the spark plug) checked the valve clearance and the intake is way off as is one of the exhaust valves. Installing the correct size shims tonight, hopefully that solves it.

@Way2Slooow - the coolant at the radiator is full. I think you were spot on with the fuel/carbon mistaken for oil.
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post #6 of 35 (permalink) Old 01-17-2017, 03:43 PM
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You may well get out of this very lightly.
Check your valve clearances and let me know where they are at.
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post #7 of 35 (permalink) Old 01-17-2017, 07:48 PM
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Sounds like you might have kissed a valve...could be slightly bent....good luck....

2004 BMW R1150SR Project Touring Bike (in-work)
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post #8 of 35 (permalink) Old 01-17-2017, 10:09 PM Thread Starter
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Late last night I installed the new shims (intake clearance was off by .12 and .05mm). Ran a pressure test (intake valves held) and manually turned the crank with no piston/valve contact. Started the bike this morning and after a few minutes of residue burn-off took it for a spin. Two noticeable differences:

-The exhaust note is softer (one exhaust valve was out of spec) / It use to sound like a tractor
-The power band is smoother / before i would hit 5k and the bike would take off similar to a vtec motor, now its a smooth linear power delivery

Fingers crossed i fixed the problem and not just a symptom... next week I have some time to take her out and push it in the canyons to see how she runs.

I appreciate the input way2slooow, if you or anyone else thinks of something else please let me know.
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post #9 of 35 (permalink) Old 01-17-2017, 11:35 PM
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It may well be that you simply had the valves "riding" a little. Normally this will make the bike hard to start. Once warm they come good. Your symptoms would be an extreme example of this. The smoke is curious. White smoke = water. Gray smoke = oil.
Always keep a record of your valve movements. This will tell you what it happening with your bike. If the same valves close up again you will know there is a deeper issue and can address it.
Hopefully all is well.
May the force be with you.
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post #10 of 35 (permalink) Old 01-19-2017, 11:58 PM Thread Starter
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And i'm back....

Finally a break in the rain and got to take the bike out and push it..... noticeable power loss. Came home checked the front cylinder and its down to 90psi. However at 90psi there is no smoke, of any color, and no miss fire. Question, is it possible i was one tooth off on the intake cam when i was reinstalling it? Or would one tooth off result in piston valve collision? I ask because it is extremely difficult to see the indicator line on the cam to line it up with the head.

Is my next step to pull the head and replace the head gasket?

Last edited by Ilostmywatch; 01-20-2017 at 12:25 AM.
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