Flywheel Damage?

[Junito]

  My Night Train 2000 95'', 257SE cams, HTCC Heads is working well and suddenly begins to fail, I remove the spark plugs and the rear piston has compression sometimes and sometimes not if, the Front has always compression. I think the flywheel was damaged because something started vibrating before it started to fail. I removed the rear head and all good. What else could it be? Thank you for your help.

[Ohio HD]

Did you take the heads apart? For the cylinder to have compression sometimes, and not others, you have to have issues with the valve(s) either not opening, or closing, or? I would take the head apart, look for loose valve seat, broken valve spring.

[Junito]

Yes I take out the head.Valves seat and spring Ok.

[Jaycee1964]

Got a Guide moving?

[Admiral Akbar]

loose valve seat..

Max

[BUBBIE]

My Guess:
Broken valve guide can hold/bind the valve open a bit on occasion and not having compression in that cylinder...

signed....BUBBIE

[02FYRFTR]

HTCC heads are prone to cracks between the spark plug threads and the intake valve seats which will loosen seat.  Clean the carbon off the head chamber and look for cracked head.  Vibration result of misfiring of the rear head more than likely.

[rbabos]

Could be a sticking valve in the guide as well. Usually some lifter noise accompanies the missing.
Ron

[rigidthumper]

Or a failed cam bearing messing up cam timing

[Ohio HD]

Or a failed cam bearing messing up cam timing

  That didn't occur to me at all, and maybe the issue.

[BUBBIE]

HOW Much NOISE was accoiated with the missing when you shut it off.... Missing a lot of compression in that cylinder (to Me) means a valve hanging open to allow it to Have No compression when he checked... Then some compression in that cylinder when checked again,,,,, Valve UN-sticking.

signed....BUBBIE

[Hillside Motorcycle]

B engine, with slipped balancer drive sprocket, could account for the vibes.
Compression, coming/going??
Scott

[Junito]

 I first remove the spark plugs and put my finger into the holes and turn it on. The front cylinder lift my finger, the rear cylinder not,the compression coming for a moment and going out and it is only the rear cylinder. The rear head and piston are in good condition

[BUBBIE]

 

Could you Have & Had a Badly blown head gasket?

IF all is good on the valves? Maybe the head gasket. Saying your finger over the front then Nothing when done on the back. Right?

signed....BUBBIE

[Junito]

Gasket OK

[Buffalo]

If it was mine, I'd pull the cam cover and check for a cillapsed lifter, broken wheel, chewed up cam etc. I would NOT restart this engine until the problem is repaired.  FWIW  Buffalo

[Admiral Akbar]

Don't need to pull the cam cover unless something look stinky from the lifter holes..

Max

[Junito]

Lets check the lifters that's good idea thanks

[BVHOG]

Did you pull the cylinder off and check the piston? htcc setup as a huge amount of weight above the pin and they are known to ruin the skirts and have the piston rocking all over the place. How many miles, around 30 thousand by any chance?

[Junito]

Piston like new...

[Junito]

 I installed  the rear head and doing the same thing no compression or a little,but when  loose the rocker arm it  make compression perfect. Maybe are  the lifters or the cams shaft?The pushrods are  in good conditions

[Ohio HD]

I installed  the rear head and doing the same thing no compression or a little,but when  loose the rocker arm it  make compression perfect. Maybe are  the lifters or the cams shaft?The pushrods are  in good conditions

You must have a damaged valve guide, valve stem, or for some reason the valve isn't closing when the cam is in the closed position, are you sure the valves are adjusted correctly? Is the cam rotating?  Did you take the heads completely apart when it was off and inspect the guides and valves?

Sorry to ask such basic questions, but we can't see what's going on of course.

[BUBBIE]

 

IF you have Adjustable pushrods, One may have come loose of the jamb nut and opened out to hold the valve open OR a bad lifter,,, sticking in the bore???

Let us Know what you find.

signed....BUBBIE

[hogmandon]

I would think you could hear the air passing by the valve when turning the engine over with plug in rear cyl. if a valve is hanging open. Have some one turn engine over with rear wheel and listen in the ports should hear some hissing some where. You also said if you loosen rockers compression comes back. did you cut heads and use stock or perfect fit PRs maybe on the edge of to long. don't know why it would not show up right away. Are oil holes in PRs or rockers pluged oil can't get out of lifters, can they pump up to much then blead down?

[Junito]

OK I find it the rear cam bearing broken.