Author Topic: What Would Cause this Explosion? (Read 2411 times)

campbmic · « **on:** March 28, 2010, 12:25:48 PM »

1975 CB550

About two months ago I installed my refreshened engine (new rings and gaskets). I havent really been able to ride it much since then on account of trying to fix charging issues and other things. I had to repair part of my oil galley with JB weld yesterday. I put fresh oil in (2.6 quarts) and an old oil filter (I couldnt find a new one and there was a big vintage bike meet right down the street). Anyways, today I got back to working on my charging issue. The bike was making a pretty nasty burning smell, which I assumed was oil burning off the pipes. On a particular kick start it felt like the kickstart was getting very hard to kick. It could have just been me over analyzing I don't know. Anyways, I checked the oil level and it seemd a little low so I filled it all the way up to the top line. The bike now had 3 full quarts of oil.

So I continued trading out stator and field coils trying to fix my charging issue and at about 8k RPM this happened.

Upon examining the carnage I realized I hadn't put the bolts back on the stator cover. I found this piece in the giant puddle of oil.

So from my deductive skills of reasoning I assume that the piece I found is a plug that goes under the crankshaft.

Im guessing it is held in place by the stator cover. What could I have damaged or broken in the fray? The bike still kicks over so thats a good sign?

fire113 · « **Reply #1 on:** March 28, 2010, 12:53:57 PM »

...not sure by the 550 but I think there was to much oil in the block.

EDIT--> when the engine is cold the (explosion-)pressure goes next by the piston(-ring) and this pressure trys to make the way through the engineventilation(<-?) out of the block but with too much oil it can't leave and it takes the way where ever it can go.
You can't compress liquits!

can't explain better, My english is to bad sorry

campbmic · « **Reply #2 on:** March 28, 2010, 01:05:45 PM »

The oil level was really low even with the recommended 2.6 quarts so I brought it up to 3 quarts and then this happened

bistromath · « **Reply #3 on:** March 28, 2010, 01:06:37 PM »

It's probably fine, as long as you didn't run it for any length of time after it started gushing. That's a main oil galley plug, so when it went, the crankshaft lost all oil pressure and started riding on the bearings. Basically like a hot start, except continuous.

Also, the CB550 takes 3.5 quarts of oil when dry.

campbmic · « **Reply #4 on:** March 28, 2010, 01:14:04 PM »

Ya as soon as the oil shot out I stopped the bike immediately. My workshop manual says on page 13 to fill the bike with 2.6 u.s. quarts of oil and that the oil capacity is 3.2 us quarts. Does anyone else have a say in how much oil there should be?

What is the purpose behind this main oil galley plug? Also, why did mine shoot off?

754 · « **Reply #5 on:** March 28, 2010, 01:19:18 PM »

It shot out because it was not held in by;
the cover

the gasket

an inner component, ie, field coil

or, any combination of the above..

fire113 · « **Reply #6 on:** March 28, 2010, 01:23:37 PM »

...BTW-> never use a old oil filter!

campbmic · « **Reply #7 on:** March 28, 2010, 01:27:25 PM »

Thanks 754, thats what I was trying to figure out. I was worried something might have broken internally, I wasn't for sure. I was planning on changing the oil again soon I guess this just streamlined the process of getting it out

Thanks fire for your help and your English is very good.

One more question, Ive heard of engines locking up and people using wd40 or other penetrating fluids to unlock them. When the engines unlock are they permanently damaged or are the just as good as they were before?

fire113 · « **Reply #8 on:** March 28, 2010, 01:45:19 PM »

...I don't tink that someting can be better then before! It has always a reason why the engine is locked.

Quote from: campbmic on March 28, 2010, 01:27:25 PM

One more question, Ive heard of engines locking up and people using wd40 or other penetrating fluids to unlock them. When the engines unlock are they permanently damaged or are the just as good as they were before?

Sporkfly · « **Reply #9 on:** March 28, 2010, 02:43:34 PM »

Why exactly were you at 8k rpm in neutral (I assume)? Revs that high without load are not a good thing.

Anyway, if you didn't have everything in place under the stator cover how were you diagnosing the charging issue?

I'm just a little confused about the circumstances of this happening. Don't destroy your bike, dude. Get that sorted out and don't be afraid to ask for help. A lot of us have been there with the charging issue. You won't have to just throw parts at it to get it charging as you can test each component fairly easily and button it back up properly.

campbmic · « **Reply #10 on:** March 28, 2010, 03:46:52 PM »

Quote from: Sporkfly on March 28, 2010, 02:43:34 PM

Why exactly were you at 8k rpm in neutral (I assume)? Revs that high without load are not a good thing.

Anyway, if you didn't have everything in place under the stator cover how were you diagnosing the charging issue?

I'm just a little confused about the circumstances of this happening. Don't destroy your bike, dude. Get that sorted out and don't be afraid to ask for help. A lot of us have been there with the charging issue. You won't have to just throw parts at it to get it charging as you can test each component fairly easily and button it back up properly.

Well about 2 weeks ago my starting issue started. I went through everything with a multimeter and everything checked out fine, yet I still wasn't charging. Theres a thread on here called "Not Charging CB550k" that scottly helped me out on and reached about 10 pages long. We replaced the regulator and rectifier even though they tested fine and it still wouldn't charge. We then replaced the stator and field coils even tough they both checked out fine. After replacing these the bike charged great. Like it says above, I squished the three yellow alternator wires when putting the sprocket cover back on and the bike stopped charging a few days later. I was in the process of switching out a field coil to see if that was the problem. I put the stator cover and all back on but forgot to put the four bolts back in.

This bike is being rebuilt from the ground up and I also have some carb issues that Im trying to solve. When I snap the throttle I get a little bit of white smoke. I was at 8k rpm trying to figure this out.

Hopefully, and going by what 754 said, this didn't cause any damage since the bike shutoff as soon as the oil gushed out.

I think my main issue with testing each component is that I have a pretty cheap electric multimeter and when you have to test the .35 +- 10% on the field coils I dont think my cheapo MM is up to it.

turboguzzi · « **Reply #11 on:** March 28, 2010, 04:26:07 PM »

that thing plugs the main oil gallery and is under high pressure, stator cover keeps it in place

this was no explosion, nothing exploded, just a stream of high pressure oil found its way out.

mount it back, refill oil, and be smarter next time. BTW, this is totally unrelated to filling your engine too much, clogged oil filter, what have you....

TG

Sporkfly · « **Reply #12 on:** March 28, 2010, 05:03:43 PM »

A good quality MM cannot be beat, I was farting around with an analog for a while and couldn't figure out my charging issues. Picked up the digital and I figured the damn thing out in about 15 minutes.

This thread makes me realize how lucky I was when I first started getting my bike fully operational. I was buzzing down the highway when I looked down and saw the stator cover wobbling a bit. Stopped right away and all my bolts had vibrated loose.

Do you have a project thread?

HondaMan · « **Reply #13 on:** March 28, 2010, 05:08:11 PM »

...and, don't rev an unloaded SOHC4 engine past 4500 RPM, per Honda's many Service Bulletin warnings on the topic. Without loads on the crankshaft, the oil in the rod journal-bearing interface does not squirt out on the power stroke, so the wristpin gets starved for oil in mere seconds. Later on, this can cause a partially seized wristpin. That can cause a thrown rod. Typically, this sort of thing happens about 5000 miles AFTER the hi-rev event, so the two events are seldom connected in the rider's mind...

I'm not writing this to scare anyone: it's just something I have seen on occasion and have written about several times here at the forums. DON'T rev these engines past 4500 RPM unloaded for more than a second or two.

If you suspect you may have done this to your bike at some time (like revving it to 7500 RPM and holding it there for 5 seconds or more) then I suggest you consider switching to a high-zinc synthetic oil (like AMSOIL 20w50) for at least the next few oil changes. The extra zinc will help polish out the score marks that may have happened to the piston pin's holes, which will sort of "heal" the area by removing the burrs on the edges of the scratches. It is these tiny burrs that will spread a seizure later (if you have one).

When I worked on (real big) heavy equipment, we used to "heal" damaged plain bearings this way with synthetic oils and added zinc. This thought never even re-entered my head until I was going through a bunch of old oilfield notes (cleaning closets) and read a report we formed from our Engineering Department, circa 1982. Then we discovered that AMSOIL products already had lots of zinc, which is good for plain-bearing engines like our SOHC4. Being synthetic is just an added plus.

(Disclaimer: no, I'm not an AMSOIL dealer, wish I was. Or even knew one.)

For checking alternators: all of the SOHC4 alternators peak before 3000 RPM. They don't make any more power above that. You might sometimes "see" a voltage rise at the battery above that, but this comes from the fact that the dwell to the coils is getting shorter, so they draw less current, and the balance from the system goes then to the battery.

campbmic · « **Reply #14 on:** March 28, 2010, 05:43:57 PM »

Wow all great info honda man! So fully synthetic zinc oil is the way to go is it very expensive or would you recommend using it at every oil change?

Also, thanks for the info on when the charging system kicks and the info on not running it without a load.

Ya spork, im glad my face wasnt right next to it when the hot oil shot off the stator cover that would have sucked!

754 · « **Reply #15 on:** March 28, 2010, 06:32:37 PM »

The reason it is there;

When they machine the cases they drill an oversize hole for the main oilfeed, it is the size of your plug. This feeds the mainbearings/rods, thru a series of much smaller holes, insuring adequate oil supply at all times.

A 750 has a similar hole higher up, with a similar plug under the dyno cover and a cap on the other end. This cap is usually where a pressure guage is mounted on 750's.

scottly · « **Reply #16 on:** March 28, 2010, 08:05:24 PM »

Mike, do you remember when you asked me what AC volts you should be reading between the 3 combinations of the yellow stator wires, and I told you I didn't know, because I had never tried it? I was going to ask you to test that very thing, while your system was working, so we would have good data to use in the future. That was before the squished wire incident. What I did realize, in retrospect, was your AC test showed something like a 4 Volt AC difference between 2 combinations, and that was roughly equal to the .4(?) ohm variation in the resistance test. The meter is WAY more accurate reading 4V than it is reading .4 ohms.

Read the 3 AC volts, at say 2000RPM, and also report the battery voltage, with the motor running, both before and after the AC test (the voltage on the battery will drop; the yellow wires disconnected will "turn off" the charging system during the test)

Spanner 1 · « **Reply #17 on:** March 28, 2010, 09:23:30 PM »

Further to Hondaman's ' don't rev the SOHC motors past 4,500 rpm unloaded', I would never rev mine past 3,000 cold, and when I start it cold I ride-off immediatly to warm it up, never let it idle or rev it to warm up..... I guess I'm just anal about that !!.... 8K

faux fiddy · « **Reply #18 on:** March 28, 2010, 09:52:55 PM »

Quote from: HondaMan on March 28, 2010, 05:08:11 PM

...and, don't rev an unloaded SOHC4 engine past 4500 RPM, per Honda's many Service Bulletin warnings on the topic. Without loads on the crankshaft, the oil in the rod journal-bearing interface does not squirt out on the power stroke, so the wristpin gets starved for oil in mere seconds. Later on, this can cause a partially seized wristpin. That can cause a thrown rod. Typically, this sort of thing happens about 5000 miles AFTER the hi-rev event, so the two events are seldom connected in the rider's mind...

I'm not writing this to scare anyone: it's just something I have seen on occasion and have written about several times here at the forums. DON'T rev these engines past 4500 RPM unloaded for more than a second or two.

If you suspect you may have done this to your bike at some time (like revving it to 7500 RPM and holding it there for 5 seconds or more) then I suggest you consider switching to a high-zinc synthetic oil (like AMSOIL 20w50) for at least the next few oil changes. The extra zinc will help polish out the score marks that may have happened to the piston pin's holes, which will sort of "heal" the area by removing the burrs on the edges of the scratches. It is these tiny burrs that will spread a seizure later (if you have one).

When I worked on (real big) heavy equipment, we used to "heal" damaged plain bearings this way with synthetic oils and added zinc. This thought never even re-entered my head until I was going through a bunch of old oilfield notes (cleaning closets) and read a report we formed from our Engineering Department, circa 1982. Then we discovered that AMSOIL products already had lots of zinc, which is good for plain-bearing engines like our SOHC4. Being synthetic is just an added plus.
(Disclaimer: no, I'm not an AMSOIL dealer, wish I was. Or even knew one.)

For checking alternators: all of the SOHC4 alternators peak before 3000 RPM. They don't make any more power above that. You might sometimes "see" a voltage rise at the battery above that, but this comes from the fact that the dwell to the coils is getting shorter, so they draw less current, and the balance from the system goes then to the battery.

Mine is a 10,000 mile bike, and was seized when I got it , likely from exposure to moisture/condensation after the carbs were left off.

One of the wrist pins was incredibly worn, to the point of not going back into the reassembly.
I wonder if this is what happend?

One rocker had the hardened surface scuffed off,too.

fastbroshi · « **Reply #19 on:** March 28, 2010, 11:46:43 PM »

Mike, I almost had this very thing happen to me the first time I rode my bike after getting my top end back together the first time. Luckily, my stator dislodged enough to interfere with the rotor turning and it killed the motor. Luckily, the bike was just idling at the time. You'd think the force would be enough to break the stator, as fragile as it looks compared to that steel rotor.

But there were just a couple of gouge marks not more than a couple mm deep in the rotor where they'd interfered. Walked it back home, uphill, with a partially sticking front brake (think Goldwing weight), and figured it out after a couple of posts here didn't conclude anything.

Good to hear your damage isn't fixable. Did you end up making any of the Rockers vs. Mods meetings?

campbmic · « **Reply #20 on:** March 29, 2010, 11:23:25 AM »

Fastbroshi- Ya I made it to Lee Harveys and Amsterdam, there were some cool bikes but mainly new triumphs. I think I saw a CB450 and a CB750. Ya, I checked the stator right after the incident and I ran my hand across it and there wasn't any rough scuffs so Im hoping that the force of the oil galley plug shut it off and the rotor didnt hit it at all.

Quote from: fastbroshi on March 28, 2010, 11:46:43 PM

Good to hear your damage isn't fixable

Rude typo

Scottly- Ya, I was in the process of testing my yellow AC voltages and I was getting like 12V 8V and 5V which is a huge difference between them. However, I cant run anymore tests until I get my new oil filter which comes in tomorrow and some oil.

fastbroshi · « **Reply #21 on:** March 29, 2010, 01:36:58 PM »

Quote from: campbmic on March 29, 2010, 11:23:25 AM

Quote from: fastbroshi on March 28, 2010, 11:46:43 PM
Good to hear your damage isn't fixable
Rude typo

Oops, and usually a stickler for crap like that. I'm Ron Burgundy??

turboguzzi · « **Reply #22 on:** March 30, 2010, 03:05:53 AM »

Quote from: HondaMan on March 28, 2010, 05:08:11 PM

Without loads on the crankshaft, the oil in the rod journal-bearing interface does not squirt out on the power stroke,

That's pretty interesting, you learn something new every day. applies only to the 500/550? Only to SOHC's? went through some of my paper documentation and could find any references. The other old school engine i have experience with are air-oil GSXR's and those have nice jets in the crank webs aiming at the pistons.

TG

Tim. · « **Reply #23 on:** March 30, 2010, 07:42:35 AM »

If that happened to me in my garage, I don't think the oil would be the only mess on the floor. Hopefully things get sorted out - sounds like you avoided a major disaster by having this happen in the garage and not flying down the freeway at 8000rpm.

News:

Author Topic: What Would Cause this Explosion? (Read 2411 times)