Author Topic: f***** disaster strikes (Read 3201 times)

pinnacle · « **on:** November 30, 2009, 09:48:26 PM »

alright so here's what happened in short i think my motor is toast. I changed my #3 intake valve ,cleaned up the head,installed new head gasket with light film of gasket sealer,installed it with pistons1-4 at top dead centre,installed cam with the notch paralel with head,torqued the head bolts down to 19 ft/lbs in the sequence prescribed,backed off tappet adjusters all the way and pinned them up with elastics and installed it.went about installing the rest and set the valve clearance last.put new oil in it and kicked it over with kick start with ignition off to get oil up to the head before starting turned the ignition on and tried starting it but it wouldn't then i realized my idle screw was completely backed off so i set it up cranked it over and sh started right up so i left it running at idle just to burn off oil and other #$%* on there took out the stethoscope gave her a listen and she sounded just dandy.so after about 10 min i gave it a quick twist of the throttle and out of nowhere i heard something go a rattle and then the engine came to a quick stop.now i'm pissed so i take out the spark plugs and number 1 spark plug is smashed up and #3 exhaust valve stuck open and obviously bent.I took a flsh light to the spark plug hole and i can see a hole through the top of the #1 piston. What the hell happened? i took my time checked to make sure everything was tight and set properly.like i said it ran good for about 10 min quietly and smooth and then out of nowhere this happened.

what do i do now? anyboby want to venture a guess what could cause this? when i put the new intake valve on #3 i did not touch the rest of the valves as they had really good compression numbers.

pinnacle · « **Reply #1 on:** November 30, 2009, 09:50:10 PM »

should have mentioned it is a 1978 cb550k

kghost · « **Reply #2 on:** November 30, 2009, 09:55:38 PM »

The Autopsy will tell.

Something smashed a hole in your piston. Probably a Valve.

Thor's Hammer! · « **Reply #3 on:** November 30, 2009, 10:12:08 PM »

Damn man. That really sucks dude! Is it possible a child might have dropped something into one of the open valve ports while you stepped into the house to get a drink or something?

My kids sometimes try to help daddy, and I could see something like that happening? Just a thought.

Spanner 1 · « **Reply #4 on:** November 30, 2009, 10:16:20 PM »

A classic case of NO top end lubrication IMO...#1 valve seized and holed #1 piston, #3 valve seized and bent...something put together wrong for oil flow to head......Bummer.

pinnacle · « **Reply #5 on:** November 30, 2009, 10:17:58 PM »

nope i wish i could blame someone else but kids were inside.i'm thinking valve bent stayed open and piston smashed into it.spark plug threads really screwed up now.have to wait til tommorow to take head off the bike was still to hot to work on.i don't no who's toes i stepped on but damn.i'm trying to stay calm but getting harder to do when i think about it.

Hush · « **Reply #6 on:** November 30, 2009, 10:26:25 PM »

Sounds like that new valve came a drift and as you say Pinnacle dropped down low enough for the piston to collect it....damn man that is really hard lines bro.....I feel your grief.

pinnacle · « **Reply #7 on:** December 01, 2009, 07:05:45 AM »

I put new vave on #3 intake the one that damaged the motor was #1 exhaust.as for poor lubrication top part of head had a lot of oil sitting there when I took off the valve cover...

pinnacle · « **Reply #8 on:** December 01, 2009, 12:29:27 PM »

well before i go and get my wisdom tooth pulled like i havn't suffered enough yet i thought i would post some pics of the damage .head is definately done damn.

can anyone suggest where to source a complete motor and what options i have as far as different motors that are a direct bolt on.anybody have an engine they care to part with?

Sam Green Racing · « **Reply #9 on:** December 01, 2009, 12:42:42 PM »

Quote from: pinnacle on November 30, 2009, 10:17:58 PM

nope i wish i could blame someone else but kids were inside.i'm thinking valve bent stayed open and piston smashed into it.spark plug threads really screwed up now.have to wait til tommorow to take head off the bike was still to hot to work on.i don't no who's toes i stepped on but damn.i'm trying to stay calm but getting harder to do when i think about it.

How can the spark plug thread be screwed up, the thread should be in the spark plug hole, not the combustion chamber where the damage was done. Are you sure you havn't put a long reach plug in by mistake, check the length with the other plugs and also make sure they all had washers on. If a valve broke, the only thing that should be damaged on the plug would be the electrode.

Sam.

Sam Green Racing · « **Reply #10 on:** December 01, 2009, 12:44:30 PM »

By the way....nice avatar

Don R · « **Reply #11 on:** December 01, 2009, 12:56:42 PM »

The piston was pounding the valve head into everything in the cylinder, I'm not surprised the plug came put hard. Sorry for your engine loss.
I bet someone here has something to get you going.

75750SS · « **Reply #12 on:** December 01, 2009, 01:00:27 PM »

You could try Cycle X for parts or an engine. I would just get a new head, pistons and rebuild.

hcritz · « **Reply #13 on:** December 01, 2009, 01:18:56 PM »

Hey Pinnacle...
Just a thought...did you tear down the head when you cleaned it up? Possible that maybe you didn't get the valve keeper keys properly seated. That might account for it running fine till it was reved.
I always bump the valves a few times with a rubber hammer to make sure.
Built a Lotus head not long ago...when I bumped one of the valves with the hammer...the keeper and spring went flying...
Keys just didn't seat properly. Would have been an expensive disaster if I hadn't checked!!!

TwoTired · « **Reply #14 on:** December 01, 2009, 01:26:38 PM »

Here's my armchair post mortem eval.
The #3 valve wasn't the only one that was bent during the cylinder cover installation event, the exhaust on #1 one also bent, but not as bad as #3, allowing the valve to seal for the compression test (stem bent on the spring side).

When the head got to operating temperature and the metal swelled, the #1 exhaust valve seized in the guide, open. Piston came up and smacked it enough times to break it off... where it banged (hammered) around and mashed the spark plug and the soft aluminum threads gave way. The holed piston means the lower end is now contaminated, and without a strip down and cleaning, it's future seems dim, too.

I had this happen to my airplane engine (from a different cause). The valve tulip broke off the stem (sodium filled valve stems). I was "lucky" the valve mashed into a U shape and found the exhaust port and lodged in the muffler before the piston crown was holed. This saved the lower end from needing an overhaul, making a $15,000 repair only $1500 to get it flying again. I still have that piston and valve out in the garage as a memento. But, the memory of the engine shaking the plane so bad that the wing tips were flexing up and down a foot is still pretty vivid.

For your replacement options, any CB550 engine will drop right in place on your frame. I think you are better off replacing the whole unit, all things considered. (Just trying to limit your suffering.)

Yoshi823 · « **Reply #15 on:** December 01, 2009, 01:45:59 PM »

Quote from: hcritz on December 01, 2009, 01:18:56 PM

Hey Pinnacle...
Just a thought...did you tear down the head when you cleaned it up? Possible that maybe you didn't get the valve keeper keys properly seated. That might account for it running fine till it was reved.
I always bump the valves a few times with a rubber hammer to make sure.
Built a Lotus head not long ago...when I bumped one of the valves with the hammer...the keeper and spring went flying...
Keys just didn't seat properly. Would have been an expensive disaster if I hadn't checked!!!

That was soooo strange...I was going to suggest the same thing with the seated valve collets & giving them a tap with a rubber mallet after initial installation.

But the valve does look as though it has parted the valve head from the valve stem at the weld point. Was this a pattern valve?

davesprinkle · « **Reply #16 on:** December 01, 2009, 03:27:38 PM »

If you didn't use the crank marks to establish timing, then it's possible the cam was mis-timed. You said you positioned the pistons at TDC. It isn't good enough to visually estimate the height of the pistons -- you have to use the crank marks. The pistons "dwell" at TDC & BDC, so you could be off by as much as 10 or 15 crank degrees.

cb650 · « **Reply #17 on:** December 01, 2009, 03:56:03 PM »

Maybe the keepers failed to seat properly. That was my biggest worry when I put new valve seals in my 650.

pinnacle · « **Reply #18 on:** December 01, 2009, 04:18:01 PM »

i think tt's assesment might be.the only valve taken off was #3 intake the rest i left alone because they had really good compression of 155 psi so the keepers were never touched on any other valve.never suspected any thing as it was idling smooth and i had taken a stethoscope to the valve cover to listen for tapping and they were just humming along coughing of fuel back into carbs had disappeared and then i heard something snap and rattle and engine just came to a screaching halt.when i removed the plug it was all mashed at the tip of it actually had a hard time removing it. when i set the cam i put pistons at tdc and aligned it to the t mark on the timming plate and set notch parralel to the head.

Spanner 1 · « **Reply #19 on:** December 01, 2009, 08:08:34 PM »

Pinnacle, you haven't said what motor this is.....but if the head receives lube from the pump via the two cylinder studs ( aka 750 ) it looks to me from photo#2 that the passages are completely blocked by that red gasket goo......

Zaipai · « **Reply #20 on:** December 01, 2009, 08:22:17 PM »

Wow, that sucks.. Sorry for your having to go thru this along with wisdom teeth being pulled. The good news is after you get it up and running you will be very happy.. I will keep my eye's and ears open for a replacement, I will PM you if I find one.

pinnacle · « **Reply #21 on:** December 01, 2009, 09:48:03 PM »

hey spanner i'm new to these motors so i can't tell you what motor it is other than off of a 78 cb550k.as for the lube can't answer that as i am not 100% sure on how they work.i did put some sealer on gasket a few hours before the gasket was installed i do know that when i removed the rocker cover the pockets under the cam or troffs were filled with oil.i obviosly screwed up somewhere one more notch in lessons learned although a heart breaking one....

Hush · « **Reply #22 on:** December 02, 2009, 02:37:11 AM »

OK I declare this postmortum over, Pinnacle my friend you have a great selection of spares but you now need a new motor to get up and running again.....anyone got a donor lying around?
I know the 500 and 550 are a straight swap and I think the 650 drops in too (don't quote me though)

bryanj · « **Reply #23 on:** December 02, 2009, 09:10:55 AM »

Any 500/550 will drop straight in as long as you get the motor complete with sprocket covers as the 500 clutch operating mech is in the cover and the 550 on the clutch case.

If fitting a 550 into a 500 you need the rear engine mounting plate from the 550 as that is where the clutch operating cable clips in (supposedly same cable for both bikes!).

As to the oil, on the 500/550 it travels up the oil galleries shown on the very ends of the pic BUT ANY goo on a head gasket is a VERY bad idea---not that this caused your problem, i happen to side with TT's diagnosis on this one and it could have been caused by a PO.

In 30 odd years that is only the 2nd dropped valve i have seen on a 500/550 and the other one was doing 13,000rpm at the time!! Similarly i have only ever seen 1 worn out crank on a 500/550

I neglected the 650 engine as an option as altough it will fit straight in it uses an "electronic" type ignition and a different generator that would call for a major re-wire job

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Author Topic: f***** disaster strikes (Read 3201 times)