Riders Of Vision

General => TechTalk => Topic started by: cvincer on August 01, 2019, 09:37:25 AM

Title: Cam Cover Blow Out
Post by: cvincer on August 01, 2019, 09:37:25 AM

Sitting at the traffic lights, engine idling, I heard a slight  'puff'  and the engine stopped.  Started it up again, but a few minutes later I could smell hot oil..& pulled over.  The problem was one of the 'plugs' of the cam cover gasket had blown outwards, causing oil to blow out the side.

Simply loosened the cam over bolts, pushed the 'plug' back in, & carried on home where I cleaned the oil off the bike.  I then got on it & went for a 10 minute ride, red-lining it in the lower gears several times........with no blow out.   Any ideas why the blow out happened at idle??

The photo shows the plug after put it back in place.
Title: Re: Cam Cover Blow Out
Post by: fret not on August 01, 2019, 01:29:16 PM
Excessive internal pressure.  I don't know why.  The cam covers each have a vent that goes to the air box, and one is larger diameter than the other.  I substituted the large vent cover from another motor for the small vent cover, so both covers now have less restrictive breathing.  I'm not sure if this is enough to prevent the blow out problem, but it should at least improve the situation a bit. 8)
Title: Re: Cam Cover Blow Out
Post by: Inheritance on August 03, 2019, 07:47:43 AM
On an unrelated note -- is that a stock Reg/Rec and was there enough slack in the wires to mount it over there? I really need to consider doing this but splicing/soldering sounds like an expensive mistake for this job.
Title: Re: Cam Cover Blow Out
Post by: George R. Young on August 03, 2019, 02:08:17 PM
The Kawasaki Concours has a similar shaped valve cover gasket and recommends a dab of silicon seal on each gasket lobe to prevent this blowout.
Title: Re: Cam Cover Blow Out
Post by: fret not on August 03, 2019, 04:18:20 PM
This issue is what the 3 Bond (Hondabond, Suzukibond, Yamabond, etc.) is good for.  It seems to resist oil pretty well, better than(most) silicone.
Title: Re: Cam Cover Blow Out
Post by: injuhneer on August 03, 2019, 11:13:08 PM
Excessive internal pressure.  I don't know why.  The cam covers each have a vent that goes to the air box, and one is larger diameter than the other.  I substituted the large vent cover from another motor for the small vent cover, so both covers now have less restrictive breathing.  I'm not sure if this is enough to prevent the blow out problem, but it should at least improve the situation a bit. 8)

Might one of the vent tubes be obstructed?

These half-round seals do age. They can harden or shrink causing exactly what happened.

Some old Maserati engines have this problem. I make a half-round aluminum plug with an o-ring to replace those. Maybe I'll give it a shot on the XZ.
Title: Re: Cam Cover Blow Out
Post by: fret not on August 04, 2019, 03:57:36 AM
You wouldn't have by any chance a table top CNC would you?
Title: Re: Cam Cover Blow Out
Post by: cvincer on August 04, 2019, 04:43:02 AM
Re all the replies:-

Inheritance ......yes it's an OEM reg/rectifier. The lead from it that connects to the one coming from the stator has been extended.
                         Think I cut the lead of a dead reg/rectifier I spliced it onto the lead from what is now the insitu reg/rect. Simple
                         job with the soldering iron & some heatshrink.   I've also put an heatsink on the engine to take away heat from
                         the stator...make sure the securing bolts you use don't foul the moving parts inside the engine.

Walt M............. No, the hose was fine.

Fretnut.............It is the rear cylinder with the larger diameter hose.  Sounds like you've put a rear cam cover on the front cylinder.
                         Where did you vent it to??  (any pics?)
 

Had thought the problem might have been related to a 'wasted' spark, but today decided to install a new cam cover gasket, and was amazed to find the exhaust camshaft had sheared......why I've  been able to happily ride around on it for the last few days can't understand.  Only having 1 exhaust valve opening must explain the blow out.   I've drained the oil but not bits of metal + nothing on the magnetic sump plug....but then again never found the 'pecker' missing from an accelerator jet. Wonder if the sheared cam had something to do with the carb balancing problems detailed in an earlier post?

Anyway, I've got a spare camshaft so will get on the road again sometime.  Thanks for the replies.

.
Title: Re: Cam Cover Blow Out
Post by: Walt_M. on August 04, 2019, 07:16:45 AM
Well, that's a new one. How many miles on this engine?
Title: Re: Cam Cover Blow Out
Post by: Prophet Of Doom on August 04, 2019, 07:22:44 AM
Only having 1 exhaust valve opening must explain the blow out.   
That would do it.  Half the exhaust would increase blow-by significantly I would think.
Never heard of that happening before.  You are very lucky it happened with the valve closed.
Title: Re: Cam Cover Blow Out
Post by: cvincer on August 04, 2019, 10:29:02 AM

   86,000 kms
Title: Re: Cam Cover Blow Out
Post by: pinholenz on August 04, 2019, 05:41:28 PM
That is astounding. Its hard to believe that the engine kept running let alone being able to redline!
Title: Re: Cam Cover Blow Out
Post by: injuhneer on August 04, 2019, 07:17:22 PM
You wouldn't have by any chance a table top CNC would you?

My machines would need a very big table. LOL
Title: Re: Cam Cover Blow Out
Post by: injuhneer on August 04, 2019, 07:22:08 PM

   86,000 kms

Interesting failure.

If the ends of the fracture are bright then the failure is recent and stress related. Like when the bearing caps are replaced or swapped without line boring. If the ends of the fracture are dark grey then the fracture has been in the making for some time.

The cam looks good otherwise. Definitely could be repaired.
Title: Re: Cam Cover Blow Out
Post by: pullshocks on August 07, 2019, 02:45:51 PM
It happened to me while I was on a trip .   Vent hose was in place and unobstructed, so I never understood why. Fortunately it happened a few blocks from my hotel and I was able to work on it in the parking lot.  I wrapped a bunch of tie wire to hold it in place.

Full write up here:  http://ridersofvision.net/rovforum/index.php?topic=13288.0

I can't believe 8 years have gone by.
Title: Re: Cam Cover Blow Out
Post by: Walt_M. on August 07, 2019, 03:59:03 PM
But, did you have a broken exhaust cam?
Title: Re: Cam Cover Blow Out
Post by: pullshocks on August 08, 2019, 01:25:49 AM
The gremlins threw a lot of stuff my way during 5 years of Vision ownership, but not a broken cam shaft.....
Title: Re: Cam Cover Blow Out
Post by: Prophet Of Doom on August 12, 2019, 12:06:24 AM
The gremlins threw a lot of stuff my way during 5 years of Vision ownership, but not a broken cam shaft.....
Does anyone here have a gremlin bell on their visions?
If there ever was a bike that needs one this is it.
Title: Re: Cam Cover Blow Out
Post by: cvincer on August 12, 2019, 09:42:43 AM

Here's a couple of photos of the camshaft.

The new cam is in the REAR cylinder but the bike won't start. FRONT cylinder tries to fire, but nothing from the REAR.  Can't understand the problem, lining up the valve timing marks is simple....& whatever is wrong withe the REAR, the FRONT should be firing....the bike running on a single cylinder.

Seems to be a mistake in HAYNES. ...when it talks about valve clearances, it says that at TDC on the compression stroke, both the front & rear cylinders will have their cam lobes pointing up, whereas on mine the REAR has it's lobes lying almost flat opposing (Inlet/Exhaust cam lobes) each other and looking at the diagram of 'Cam Sprocket's in HAYNES ...how could the rear have the lobes upwards?

The XZ service manual makes the same mistake...plus when talking about valve timing for the REAR cylinder, says the lobes at TDC on the compression stroke should be facing each other, whilst the accompanying diagram shows something different.

Anyway, don't know why mine won't start;  at the weekend I'll try a rain dance & then maybe a lump hammer.
Title: Re: Cam Cover Blow Out
Post by: injuhneer on August 16, 2019, 09:34:16 AM
There was another thread that covered the cam positions for timing. I would have to find it but maybe one of the long-time members can point you to it.

The manual must be incorrect. At the absolute minimum the difference in angle of the cams relative to each cylinder TDC must be at least 70*.

If the rear cams are drastically out of time it seems there should be ignition firing through the intake or exhaust when cranking.
Title: Re: Cam Cover Blow Out
Post by: kevin g on August 17, 2019, 12:33:17 PM
I recently corrected the front cylinder cam timing on my new to me vision and had to be careful interpreting the manual.  The front cylinder is described well but the rear is glossed over and needed a bit of study.  The front cylinder should have the cam lobes facing each other at TDC on compression and the rear cylinder has them facing away from each other on compression.  It sounds like you have them oriented correctly.

My bike would not start with the YICS ports open so check for that.  I capped them off and it runs but it seems to run better with the YICS chamber in place.  I have not ridden this yet, just running on the lift.  I have to get a working petcock for my '83 first.
Title: Re: Cam Cover Blow Out
Post by: cvincer on August 17, 2019, 10:13:43 PM

Out of interest I attached a timing light with an inductive pick up clamped to the FRONT cylinder HT lead & pressed the start button ......yep, the 'flash' picked up the FRONT cyl timing point.   

Put the inductive lead on the REAR cyl HT lead & the 'flash'  did NOT pick up the REAR cyl timing point.  Perhaps I have somehow disturbed things in the lower part of the engine, I'll have to look inside my 'spares' engine to see how things might have been disturbed in the lower part of the engine....but believe the FRONT cyl should still fire & it doesn't, conundrum.

Over the last 17 years have run the bike with & without YICS (obviously capped off the YICS ports), without problems.

Re the petcock ......spares are so expensive to source in my location (postage is a killer), bought a non-vacum petcock off ebay for peanuts (less than the cost of the spare I was seeking); no problems with it in the years it has been installed.

.
Title: Re: Cam Cover Blow Out
Post by: Prophet Of Doom on August 18, 2019, 12:12:44 AM
You could try swapping the TCI inputs, if it starts sparking on the other side you will know that the TCI is good, and pickups are bad
Title: Re: Cam Cover Blow Out
Post by: cvincer on August 30, 2019, 05:54:32 AM
Pod ......... The spark plugs both spark, but whilst the 'flash' from the timing light picks up the FRONT cyl timing mark (when the timing light inductive pick up is attached to the FRONT cyl HT lead)  , the 'flash does not pick up th eREAR cyl timing mark (when the timing light inductive pick up is attached to the REAR CYL HT lead).

Below a photo showing how my REAR cyl cams lie at TDC on the compression stroke  +  a photo showing the timing mark in the bowels of the engine at the same moment  (TDC on the compression stroke)..........all looks good to me, but still will not start.


Has anyone got an engine on the workbench, & can advise (photo) of how their REAR cyl cams lie at TDC on the compression stroke?

.
Title: Re: Cam Cover Blow Out
Post by: Prophet Of Doom on August 30, 2019, 09:05:51 AM
Sorry Cvincer, I should have read your post more carefully. 
For setting the cams, read Fuzzlewump's post here
http://ridersofvision.net/rovforum/index.php?topic=15014.msg138021#msg138021 (http://ridersofvision.net/rovforum/index.php?topic=15014.msg138021#msg138021)
As well as pointing in opposite directions, On one cylinder (sorry I cant remember which) they stick more upwards, on the other they lay flatter.  They are not opposites of each other.  Don't worry too much about it.   When set to the appropriate timing mark, If the punch marks on the cams point straight up then you are golden.


The relationship between the timing marks on the flywheel and the spark plug firing has nothing to do with the cams of course -
There are three marks on the flywheel


|T is TDC for the FRONT cylinder.  Use this mark to set the cams and to measure valve clearance on the front cylinder,
|   is TDC for the REAR cylinder.  Use this mark to set the cams and to measure valve clearance on the rear cylinder
|___| is the timing range for the FRONT Cylinder at 1100RPM.  There is no timing range marked for the rear cylinder.  Because the pickup coils are a one piece unit, if the front is correct, then the rear must also be correct. 


If the front spark does not light up the timing range, then you have either put in the pickups incorrectly, or forgotten to insert the woodruf key in the crank
Title: Re: Cam Cover Blow Out
Post by: cvincer on September 15, 2019, 11:37:07 AM
So about 6 weeks of trying to get it going but no luck, my last idea was a video:-

With spark plug lying on cam bearing cap, took video with the engine turning over.  Watching video frame by frame,  shows the plug sparks @ TDC compression stroke & TDC exhaust stroke (the bike has a 'waste' spark ignition system)...so the spark is happening when it should.

Looks like it's off to the Yamaha shop, where all the mechanics are younger than the bike, & charge A$120 / hr.

.
Title: Re: Cam Cover Blow Out
Post by: Walt_M. on September 15, 2019, 01:07:41 PM
I see your frustration, that is a nice fat spark but the plug looks very wet. Too many things can happen to these things when they set too long.
Title: Re: Cam Cover Blow Out
Post by: cvincer on September 24, 2019, 04:30:41 AM
So the m/cycle mechanic   (turned out to be A$160/hr 'diagnosis' fee) said the problem was no compression (which I had never thought of testing as it was running before cam replacement + turned the engine over many times by hand after replacement & before using starter button) ...... and the problem was one of the exhaust valves.

At 70yrs I'm not sure how easy it would be to take out the engine by myself, with nothing more than a jack to help.

How hard/easy is it to take out the engine?
Title: Re: Cam Cover Blow Out
Post by: WGuaire on September 24, 2019, 08:17:48 AM
Can you get to the heads without pulling the motor?
Title: Re: Cam Cover Blow Out
Post by: cvincer on September 24, 2019, 10:29:58 AM
The front cyl head looks like it comes off with the engine insitu.....but my problem is the rear cyl & no room to remove the head with the engine insitu.
Title: Re: Cam Cover Blow Out
Post by: WGuaire on September 24, 2019, 01:06:44 PM
There is a unused motor mount on the front of the motor. When you detach the regular motor mounts the engine can be secured so it doesnít just drop like a brick. There must be the same in the rear. Configure a motor support on casters.
  Iíll check on my own Vision.
Bill
Title: Re: Cam Cover Blow Out
Post by: fret not on September 25, 2019, 02:13:48 AM
Harbor Fright has a hydraulic motorcycle jack for about $89us.  It would be a spendy item for one use, but it is very helpful when you need it.  I have one for use with my KLR 650, and find that it works well.  I would never have bought one but a friend has one and explained how it has helped him.  He has been through several KLR motors, and has several other bikes that he takes care of. 
Title: Re: Cam Cover Blow Out
Post by: Prophet Of Doom on September 25, 2019, 06:10:48 AM
At 70yrs I'm not sure how easy it would be to take out the engine by myself, with nothing more than a jack to help.

How hard/easy is it to take out the engine?
I'm not quite 70, but it's relatively easy to drop the engine single handedly. I've done it 4 or five times.  I don't use a jack, but lower the engine down with two ratchet tie-downs without the ratchet.  I just make two giant slip knots and with a tight angle there's enough friction that you can lower it with one hand while using the other to guide it.


Getting it up is pretty much the reverse, but I use the ratchets.