Bike died while riding and won't start - Page 3 - Honda Rebel Forum
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post #21 of 52 Old 08-21-2016, 09:41 PM
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It is hard to tell for sure from the shaky video, but that does not look or sound normal to me. It seems like the cam is having trouble opening the valves.

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post #22 of 52 Old 08-21-2016, 09:43 PM
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What is the valve lash?

1999 Honda Rebel CMX250C
2003 Harley Sportster 883 Hugger
1998 Harley FXDWG Dyna Wide Glide
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post #23 of 52 Old 08-21-2016, 10:03 PM Thread Starter
 
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Left:
Exhaust - .05mm (.002)
Intake - .08mm (.003)

Right:
Exhaust - .04mm (.0016)?
Intake - .08mm (.003)
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post #24 of 52 Old 08-22-2016, 09:53 AM
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Those exhaust valves are a little too tight for me. I usually set the intake to .003 and the exhaust to .004 to be sure they close after the engine gets hot to prevent burning a valve. They may be fine, but now it is time to do a leak test.

If you can't borrow, or get access to a leak down tester, you may be able to find out all you need to know by just putting some air in the cylinders, and listening for where it goes if there is a big leak.

The 10mm connector or adapter from the compression tester you used can probably be connected to an air hose with some adapters. Screw the 10mm connector into a spark plug hole and add some air pressure. It won't take a lot of pressure to hear where the leak is if you have a problem. Be sure both intake and exhaust valves are closed, i.e. loose rockers. It is best to do it at TDC so the air won't try to push the piston down, and it is easier to hold the flywheel and prevent rotation.

Air coming out the exhaust is an exhaust valve leak. Air coming through the carb is an intake valve leak, pull the air filter so you can hear it. Air coming out of the crankcase is bad rings or pistons, pull the oil dipstick so you can hear it. Air coming out around the valve stems in the head is valve seal leakage.

A true leak down test would measure the amount of leakage, but you are just looking for excessive leakage at this point. If you have a bad problem, you should be able to hear where the air is going. Google leak down test and you should be able to find more info, and youtube videos.

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2003 Harley Sportster 883 Hugger
1998 Harley FXDWG Dyna Wide Glide
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post #25 of 52 Old 08-23-2016, 05:55 PM Thread Starter
 
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Yeah I would set it to those numbers if I get the chance. The previous owner set them .002 cause that's what this manual states. So I did the leak-test and it's leaking from exhaust and intake. Pulled the oil stick. It's possible that air is leaking from crankcase but I didn't hear it.
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post #26 of 52 Old 08-23-2016, 06:35 PM
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Sounds like you have some burnt valves. I'm a little worried about a bent valve too due to the rough spots you found trying to turn the engine.

If you are sure the valves were closed (rockers loose) while you did the air test and heard the air leak, then I guess it is time to pull the head and see what you have.

I feel pretty uncomfortable telling someone to pull an engine apart based solely on a conversation without ever looking at it myself. So many things you or I may have missed if you are not familiar with what you are looking at. How bad did the air leak sound? Both intake and exhaust? Anything coming out around the valve stems?

I wish at the very least that some of the other experienced mechanics on here would chime in and either agree on the diagnostics, or tell me I'm crazy. Where are you guys?

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2003 Harley Sportster 883 Hugger
1998 Harley FXDWG Dyna Wide Glide
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post #27 of 52 Old 08-23-2016, 07:08 PM Thread Starter
 
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Yeah, I'm sure the valves were closed while doing the test. I didn't spend much time on valve stems, so I'll do another test after finishing up the yard. Leak from the exhaust was pretty bad, not so much from intake, but it's there.

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Originally Posted by 76Paw View Post
I wish at the very least that some of the other experienced mechanics on here would chime in and either agree on the diagnostics, or tell me I'm crazy. Where are you guys?
Ha I was thinking this 76Paw guy is pretty helpful but was wishing more would chime in too. Maybe I scared people off with some dumb questions. It's true, I don't know much about these things but I'm willing to learn and follow advice/manual, supply photos/videos, and try to be careful with what I'm working on. I heard these bikes were easy to work on so it was kind of a perk to me when I got it. I want to learn. It's my only form of transportation, and it can't run. So when it comes to scary things like taking the engine apart, I'm willing.
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post #28 of 52 Old 08-23-2016, 07:52 PM
 
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@76Paw I too feel uncomfortable with long distance wrenching..
defiantly something wrong if OP had the plugs out when manually turning over. tried to watch rocker action camera shake at the moment of catching and release I couldn't tell much..

I might remove the rocker assemblies and see how well she turns over without cam having to depress the valves
than again with those compression test results one way or another looks at least a valve job and/or P&C's

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post #29 of 52 Old 08-23-2016, 08:36 PM Thread Starter
 
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I'm not noticing any leaks from valve stems.

I'll probably remove the rocker assemblies tonight and see how it goes.
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post #30 of 52 Old 08-23-2016, 09:26 PM
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If you haven't pulled the rockers yet, can you turn the engine and determine exactly what is happening with the valves when it gets hard to turn. Which, if any valves are opening or closing? Is it at the beginning of a valve being opened, or halfway open, or fully open, or beginning to close, etc. Is it happening at only one spot and one valve, or is it happening in multiple locations, or on multiple valves at the same spot, or just random? It may help point to the problem area.

Also was the air leak worse on one cylinder or the same on both?

1999 Honda Rebel CMX250C
2003 Harley Sportster 883 Hugger
1998 Harley FXDWG Dyna Wide Glide
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