SuzukiSavage.com - Print Page

SuzukiSavage.com
/cgi-bin/YaBB.pl
General Category >> Rubber Side Down! >> Dropped valve
/cgi-bin/YaBB.pl?num=1445947173

Message started by Dave on 10/27/15 at 04:59:33

Title: Dropped valve
Post by Dave on 10/27/15 at 04:59:33

Forum Member "Cadence" bought a bike with a dropped valve. He is going to convert the bike to an electric bike....so he is selling off parts in the Marketplace.

His engine has a dropped valve...the previous owner was cruising down the highway and the engine stopped.

http://i.imgur.com/AnTMNOO.jpghttp://i.imgur.com/lc1NLvF.jpg

I have emailed Cadence to see if he can update us on the mileage the bike had.

What causes a dropped valve in a Savage? Youzguys has 138,000 miles on his bike and the cylinder head has never been off the bike, and his valves are still going strong. The photos of the dropped valve don't show the white color what we are used to seeing on the exhaust valves of a good running engine - I suppose the big holes in the top of the piston allowed oil to pump out into the exhaust while the engine was coming to a stop. Does the white go away after an engine has been in storage for an extended period? I know that every used engine I have opened up always has black oily looking carbon in the head.

Title: Re: Dropped valve
Post by DesertRat on 10/27/15 at 06:53:18

Lean fuel mixtures can burn valves.

http://www.ssch.com.au/trade-news/a-basic-guide-to-engine-valve-failure/

Title: Re: Dropped valve
Post by Dave on 10/27/15 at 07:36:53

I had a VW Rabbit GT that burned a valve.....it was geared low and would turn 4,000 rpm at highway speeds - and after 100,000 miles the valve was eroded away behind the hardened face on the valve. Since the engine was fuel injected it most likely ran somewhat lean mixtures. The problem first showed up as a rough idle and the burned valve created very low compression on that cylinder when I did a compression check.

For a valve to "drop"....the stem usually has to stretch and become weakend. I would think that the stretching would cause the valve clearance to go away....and pretty soon the valve would not reach the seat anymore. I just don't understand what causes the head to come of the valve....maybe I should do an internet search while I am eating lunch today.

Title: Re: Dropped valve
Post by LANCER on 10/27/15 at 08:25:39

That valve did some dancing in there !

Title: Re: Dropped valve
Post by Cadence on 10/27/15 at 08:37:35

http://i.imgur.com/FkWAE2R.jpg

Just holler if you guys want more pictures of the engine. I'm very curious as to how this happened too!

Title: Re: Dropped valve
Post by verslagen1 on 10/27/15 at 08:38:10

Maybe 2 causes, usually cam chain, sometimes stuck valve.
Normally you only see 1 valve busted, maybe rocker design, 1 arm maybe stiffer than the other.
Or lubrication/cooling, oil does both and oil does pool up some around the valves.
I don't think I've seen any burnt valves.

Title: Re: Dropped valve
Post by Serowbot on 10/27/15 at 08:40:09

Any chance something hard blocked the valve?...
Like a shattered piece of sparkplug insulation?... :-/...

Title: Re: Dropped valve
Post by Dave on 10/27/15 at 08:47:16

2234233E26333E25510 wrote:

Any chance something hard blocked the valve?...
Like a shattered piece of sparkplug insulation?... :-/...

From what I have seen on doing an internet search......postmortem analysis of these is nearly impossible. The loose valve piece tears everything up and destroys any evidence of what happened first.

Title: Re: Dropped valve
Post by justin_o_guy2 on 10/27/15 at 18:29:16

Intriguing topic, innerwebs loaded with ideas..

ue to manufacturer quality issues certain engines are more prone to dropping a valve seat during operaiton. This usually occurs when the engine is hot, from heat distortion, due to Aluminum's ability to expand 5 times the rate of steel. The aluminum material that holds the valve seat will expand and hold the valve seat with less pressure. As the valve seat becomes less restrained, stress from regular operation can work it lose completely, disbanding it from the aluminum head. Once this occurs the movement of the valve will usually break the valve seat insert into pieces, effectively eliminating any compression in the corresponding cylinder, and creating a lot of damage fr
Dave, are any seats knocked out?
If some of all of them are in place, pretty much shoots that down.

Title: Re: Dropped valve
Post by Dave on 10/28/15 at 04:07:12

I don't know the exact number - but I have seen several damaged engines and heads on this forum or on eBay. All of them have dropped one exhaust valve into the cylinder - I am not aware of any seats coming loose.

On some of the internet discussion about dropped valves, the cause is suggested as over revving the engine to the point that valve float occurs, and the valve does not follow the cam on the way back down.......and the piston hits the valve head. Until somebody that was actually riding the bike when the valve failed comes along and tells us what they were doing when the engine failed......we are just speculating about how the Savage engine occasionally drops a valve.

I also just got photos of the rockers and cam from this engine. With only 9,500 miles on the bike....how does this much wear occur on the cam and rockers? This is the same damage to the cam and exhaust rocker that was on the bike I just bought....and it had 3,800 miles on it. We can only guess that the oil the original owners were using did not have enough ZDDP in it. Wonder if the cam wear and increased valve clearance can lead to valve failure?

http://i64.tinypic.com/2mdh07r.jpg

http://i64.tinypic.com/jph0za.jpg

Title: Re: Dropped valve
Post by Gary_in_NJ on 10/28/15 at 05:47:24

Those first two photos are impressively ugly. There are a number of things that could lead to a dropped valve. Without knowledge of progressive signs of failure (compression, oil use, jetting) or parts recovery, it's just speculation.

Title: Re: Dropped valve
Post by Steve H on 10/28/15 at 15:46:26

I've always been told that excessively loose valves can be a problem because of the hard smack against the valve instead of the steady increase in pressure.

Not sure if it's true or not. Never seen anything to back it up.

Title: Re: Dropped valve
Post by Kris01 on 10/28/15 at 16:37:09

When adjusting the valves, isn't a little loose better than too tight? Or do I have that reversed?

Title: Re: Dropped valve
Post by justin_o_guy2 on 10/28/15 at 20:20:31

too tight and they don't close. Certain problems.. burned valves at best.
Too loose, noisy, and I suspect the smashing of cam into lifter/rocker allowed by the loose adjustment leads to at best, diminished performance, because thousandths of an inch are the differences between cam grinds and an adjustment that leaves several thousandths of an inch of lift for no reason other than being afraid to adjust them in the tight end of the manufacturers specs just doesn't make sense to me. I understand that the first time or two, but, once one has successfully been in and out, and it's obvious that reading, feeling, the gauges and getting TDC right, then push the envelope a bit. I have exactly nothing to demonstrate that the tight end of the specs is better for the cam, rockers and performance, but it's my opinion.

Title: Re: Dropped valve
Post by Art Webb on 10/29/15 at 20:28:16

18213A206362530 wrote:

When adjusting the valves, isn't a little loose better than too tight? Or do I have that reversed?

the vast majority of motorcyclists agree that it's best to go with the 'loose' end of the spectrum
These are guys tuning for longevity, not power, race crews might prefer the tighter side

Title: Re: Dropped valve
Post by justin_o_guy2 on 10/29/15 at 22:46:32

They are tuning for safety as they perceive it . Give one mechanical reason why the SPECIFICATIONS listed by the manufacture would lead to early demise. A RANGE of valve lash settings exists. Just as oil. Inside the high and low marks, accepted.
I at least postulated a theory as to Why the tight end is better for longevity. You quoted an unconfirmed consensus.

Title: Re: Dropped valve
Post by Steve H on 10/30/15 at 04:00:11

Here's a good article about valve lash and why you might want certain settings.

http://www.enginelabs.com/engine-tech/cam-valvetrain/valvetrain-tech-lash-is-much-more-than-just-a-little-gap/

Title: Re: Dropped valve
Post by Dave on 10/30/15 at 05:08:06

One possible cause of the "dropped valve" might be the worn exhaust rocker providing way too much valve clearance - this would prevent the cam from gently lowering the valve down onto the seat, and the valve would close more aggressively than it would with proper clearance. If we can find that other dropped valves also had a worn exhaust rocker....that might be an indication of the cause. The bike that I just purchased and brought out of long term storage had a badly worn exhaust rocker - but I checked the valve clearances before I took things apart and the clearances were not excessive....that might be an indication that someone adjusted the valves and corrected for the wear in the rocker.

When I adjust my valves I try and get them closer to the minimum clearance so that the engine makes less valve noise. The clearance is supposed to be between 0.003" and 0.005", I have a 0.003", 0.004" and 0.005" feeler gauges. The 0.003" is very flimsy and hard to work with - so I use the 0.004" and try to get a pretty tight fit....and once I get what I believe is close I try the 0.005" and I don't want it to slide through at all. I want the 0.004" to slide through with some tightness, and last I check the 0.003" and I want to to slide through with just a bit of drag.

Title: Re: Dropped valve
Post by Cadence on 10/31/15 at 01:49:07

Here are more pictures I thought were interesting:
http://i.imgur.com/wAYyfdY.jpghttp://i.imgur.com/HU4Q8tv.jpghttp://i.imgur.com/eRKN6jt.jpghttp://i.imgur.com/CnW2Geb.jpg

Title: Re: Dropped valve
Post by Art Webb on 10/31/15 at 11:04:02

4E5157504D4A7B4B7B43515D16240 wrote:

because looser lash gives more room for error
adjust loose and get it off a thousandth and you have a slightly tighter or looser clearance than you expected
Adjust for minimum clearance and get it wrong on the tight side and you get a non running motor and maybe a hole in your piston or burned valve

what do you prefer, loss of maybe a 1/4 HP, or loss of an engine?
I tend to go with the several thousand guys who say 'go loose'

though in truth I prefer the middle of the road valve lash, like Dave, that way I'm neither loose nor tight

Title: Re: Dropped valve
Post by justin_o_guy2 on 10/31/15 at 11:15:21

I stayed IN TOLERANCE. On the tight End, not the tightest , I'm no idiot. People leaving them slapping because
That's safe, well, that is for them. The book gives a range to operate in. I chose the tight end. My bike ran well, no valve issues, and wasn't clicking like mad. It sounded good, considering the valve train design. I offered a
Mechanical theory as to WHY the tight end might give longer life and better performance. I got back nothing.

Title: Re: Dropped valve
Post by Art Webb on 10/31/15 at 11:31:18

no, you got the following:
adjust to the tightest possible clearance, and get it wrong, you can wreck your engine
That's a valid mechanical reason not to go to the tightest clearance
you might never get it wrong, but others are not old hands at this, and can
I have watched newbs force feelers between valves and adjusters thinking they weren't using excessive force, and then wind up scratching their heads;
I never said you were wrong to adjust tight, I said I and MANY other folks with mechanical experience prefer a bit more leeway, and FOR SURE I wouldn't advise a newb to try for the tightest possible clearance
Then there's also the question, does the engine loose or gain tolerance as it heats up?
I don't know the answer to that, and I'm not opening a hot engine to find out, I simply stick with a middle of the road adjustment, so I know absolutely I'm neither loose nor tight

Remember the guy on here recently who let a 'mechanic' adjust his valves and the cylinder pressure went form 180 to 72?
THAT'S why I don't try for minimum tolerance

Title: Re: Dropped valve
Post by justin_o_guy2 on 11/03/15 at 22:28:27

I admit, it took a lot long longer. Check, check and recheck.

Title: Re: Dropped valve
Post by Art Webb on 11/04/15 at 09:37:03

yep, that's the difference between someone who loves fiddling and someone who doesn't
There's nothing wrong with running minimal 'in spec' clearance, and for the record, I believe you may be right about extending the valve train life that way, so long as you're anal about checking yourself, and you don't sort of 'overrun' service intervals at times
Me and you also have differing experiences with valve train clearances
The bikes I've had that I actually had to do a few adjustments on were 'shim over bucket' designs, and the clearances always shrank over time
the 'screw type' adjusters I've worked with were in old car engines (iron block, iron head) and those also shrank over time, aside from one old Chevvy that one of the adjusters started mushrooming pretty quickly at the tip (THAT got replaced)
you on the other hand have seen clearances grow, IIRC other discussions we've had about it
so in my case, I always went to the loose end, and waited till the clearance shrank to the tight end, then readjusted
Now that I'm a little less sure of myself and a bit more cautious, I tend to look for the middle ground when adjusting valves

Title: Re: Dropped valve
Post by Art Webb on 11/04/15 at 09:56:14

Dave how about some head pics?

Title: Re: Dropped valve
Post by Serowbot on 11/04/15 at 09:59:24

I put them in the middle,... one way will give more lift, and make more power,.. but the vales need seat time to cool...
..'course, I check them so rarely... who knows where they wander off to... ;D...

Title: Re: Dropped valve
Post by Art Webb on 11/04/15 at 10:01:41

Given how hard they are to access on the Savage (crappy access, the designer should be slapped) I don't blame you, I'd really prefer to just forget the whole mess

Title: Re: Dropped valve
Post by smokin_blue on 11/04/15 at 10:01:57

Dave, how tight is the valve guide? I had a Subaru that would get an intermittent misfire on #2 cylinder and it took the dealer for ever to find it. Finally found the guide was loose and would intermittently slide out with the valve and sometimes hold the valve open causing a misfire that the ECU would record. Is it possible the guide slid out and held the valve open and the piston went smack and snapped it off?

Title: Re: Dropped valve
Post by smokin_blue on 11/04/15 at 10:04:33

687B7D7E6C6B6B090 wrote:

Given how hard they are to access on the Savage (crappy access, the designer should be slapped) I don't blame you, I'd really prefer to just forget the whole mess

Art, these are a walk in the park...ever done an adjustment on a shim under bucket head on a modern sport bike?

Title: Re: Dropped valve
Post by Dave on 11/04/15 at 10:09:09

This isn't my bike....I grabbed the photos from cadence, he is parting this bike out in the Marketplace. He bought the bike this way and will be building an electric bike with the parts he keeps.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1444532386

He states the lady he bought the bike from was riding it, and then it just stopped.

Title: Re: Dropped valve
Post by Art Webb on 11/04/15 at 10:14:00

done one on a Yamaha crotch rocket
Getting to them was a pain, and pulling the fool cam to check every time you replaced a shim was a pain, but getting the gauge IN there to CHECK the clearance wasn't much of an issue, once you got all the crap out of the way, the valves were pretty much exposed once you got the cover off
this bike has a too small and badly placed inspection port that made getting the feeler in there a total pisser
I broke one of my feelers trying to bend it into a shape that would work

Title: Re: Dropped valve
Post by smokin_blue on 11/04/15 at 16:10:17

agreed. I do miss the days of sport bikes having threaded adjusters.

here is the best thing I have found for the S-40 engine. brought to you by our friends at motion pro. only $5.50 each

http://www.motionpro.com/motorcycle/partno/08-0393/
and
http://www.motionpro.com/motorcycle/partno/08-0394/

Title: Re: Dropped valve
Post by FLDoug on 11/05/15 at 10:53:51

0D363B2C3D312A2C373F322D5E0 wrote:

Dave, my daughter was riding an '87 with 9600 miles on it running Valvoline MC oil at 60 mph when someone decided to make a right turn without using their turn signal. She used the brakes and downshifted at the same time. She said the engine revved high and then it stalled and she rolled off the road. The engine dropped one exhaust valve and the internal damage was similar to the damage seen in the engine pictures Cadence has provided.

Title: Re: Dropped valve
Post by Dave on 11/05/15 at 11:17:50

223134233535460 wrote:

Interesting information.....so maybe the dropped valves come from operator error. Like the one you mentioned....or maybe a new rider forgetting which way to move the shift lever when accelerating and going down a gear........ instead of up one.

Title: Re: Dropped valve
Post by Art Webb on 11/05/15 at 21:04:39

7F6163676562536E6079690C0 wrote:

those puppies WILL be getting ordered one day, had my eye on them a while, life keeps getting in the way