Author Topic: Cam Cover Blow Out  (Read 684 times)

kevin g

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Re: Cam Cover Blow Out
« Reply #20 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.

cvincer

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Re: Cam Cover Blow Out
« Reply #21 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.

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Prophet Of Doom

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Re: Cam Cover Blow Out
« Reply #22 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

cvincer

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Re: Cam Cover Blow Out
« Reply #23 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?

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« Last Edit: August 30, 2019, 09:30:22 AM by cvincer »

Prophet Of Doom

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Re: Cam Cover Blow Out
« Reply #24 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
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

cvincer

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Re: Cam Cover Blow Out
« Reply #25 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.

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Walt_M.

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Re: Cam Cover Blow Out
« Reply #26 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.
Whale oil beef hooked!

cvincer

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Re: Cam Cover Blow Out
« Reply #27 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?
« Last Edit: September 24, 2019, 10:26:37 AM by cvincer »

WGuaire

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Re: Cam Cover Blow Out
« Reply #28 on: September 24, 2019, 08:17:48 AM »
Can you get to the heads without pulling the motor?

cvincer

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Re: Cam Cover Blow Out
« Reply #29 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.

WGuaire

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Re: Cam Cover Blow Out
« Reply #30 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

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Re: Cam Cover Blow Out
« Reply #31 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. 
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

Prophet Of Doom

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Re: Cam Cover Blow Out
« Reply #32 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.