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General Category >> The Cafe >> Camshaft/Rocker damage - sidestand issue.
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Message started by Dave on 11/12/15 at 04:35:08

Title: Camshaft/Rocker damage - sidestand issue.
Post by Dave on 11/12/15 at 04:35:08

Recently I bought a used Savage with only 3,800 miles on it, and the right side rocker and cam were badly worn.

http://i68.tinypic.com/2lx8h3.jpg

http://i67.tinypic.com/j5fd6a.jpg

There have also been a couple of other bikes on the forum that have this same issue, and it got us to speculating that the damage is caused by idling the bike while it is resting on the side stand. There is a small rectangular oil well beneath the cam, and when the bike is leaned over onto the side stand, the oil is moved over to the left side (intake) cam lobe, and the right side (exhaust) cam lobe may not get any oil to dip into.

http://i68.tinypic.com/29bitf.jpg

More recently I have been looking at the way the upper end is lubricated, and I believe the system also tends to starve the right side cam lobe when the bike is on the sidestand and idling. The oil is fed up through the cylinder and into the cylinder head. There are oil passages that are drilled to take the oil to each one of the cam journals and lubricate them. The left side cam journal is closed on the end, and the cam has a small notch on the left side that allows the oil to feed into the left end of the camshaft - which is hollow. The oil goes into the left side of the camshaft through a large hole, and travels along the hollow camshaft to the right side, which has a small hole at the cam gear end. As the oil travels through the center of the camshaft, it first comes to a small hole that is drilled into the base of the intake cam lobe, and it allows oil to pass through the cam to lubricate the intake rocker just before the valve begins to open....and what oil doesn't pass through this hole continues to travel to the hole that is drilled in the exhaust cam lobe, where it can flow out the hole to oil the exhaust cam lobe and rocker..........and whatever oil is left over continues to the right side of the cam and it flows out the end and lubricates the cam chain and chain guides.

http://i67.tinypic.com/auhz4l.jpg

So....when the bike is on the side stand and idling slowly, the oil pump is flowing very little oil, and most of that oil flow goes to the bottom end, and a small amount of oil reaches the cylinder head. What oil does reach the head first goes to the cam bearings, and then the left side cam bearing allows some oil to flow into the left side (downhill end) of the cam. The small amount of oil most likely travels to the intake cam lobe which is on the left/downhill side, and it flows out the hole drilled in the intake lobe of the cam.......most likely on the bikes that were damaged there is little or no oil left to climb up the hollow center of the cam to get to the right side exhaust lobe, and it gets starved for oil and is damaged. Once the damage begins and the cam and rockers are scored, I believe the wear accelerates and occurs even when the bike is level and up at operating speed.

So, I believe the bike should never be started and allowed to run on the side stand. The folks who like to start their bikes and let them warm up on the sidestand while they put on their gear may be doing more harm than good. My recommendation is that you put your gear on, get on the bike, turn on Raptor petcock if you have one, grab the handlebars adn pull the bike upright and fold up the sidestand, pull on the choke if you need to, and then start the bike. Warm the bike up while holding the throttle open a bit to provide a fast idle for 30 seconds to a minute - then push in the choke and ride off slowly and don't apply a lot of throttle for a mile or so and allow the engine to warm up gently. (If you need the choke to ride smoothly for a mile or two then leave it on, and push it in when the bike will run smoothly without the choke).

And it is vitally important that you keep the idle speed up above 1,000 rpm.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by Oldfeller on 11/12/15 at 08:08:39

Well thought out -- I'd add it to tech section and to the "Everything a newbie should know" list.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by Serowbot on 11/12/15 at 09:23:15

I never let a bike or car "warm up"...
Start it, with choke if needed,.. then ride gently for the first couple minutes...
Oil warms faster, and circulates better...
No sitting and idling... (especially not with cold oil)...

Good info, Dave...

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by verslagen1 on 11/12/15 at 09:25:39

Here's another way of looking at it.
At the recommended idle speed (1000 to 1200 rpm) we have 5 psi of oil pressure. (and 50 at speed)
there's about 30 inches of Head pressure per psi.
there's about 14" of rise between the oil pressure port and the head.
and running thru an oil line about a 1/4" in diameter.
So 5psi going thru an oil filter running up a skinny line while cold.
Now drop the rpm to harleyesque level and the psi drops to 3 or 4 psi at the pressure port, drop it a psi for the filter, drop it again for going up a skinny pipe while cold... anything left? not much.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by Serowbot on 11/12/15 at 10:17:50

Ride your bike upside-down for the first 3 minutes.... ;D...

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by Art Webb on 11/12/15 at 21:06:34

I never have made a habit of warming up the bike on the side stand, but I will be doing it not all from now on

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by justin_o_guy2 on 11/12/15 at 21:13:35

Thanks Dave, now I can stop pussyfooting around and saying
There is some speculation,,,
Cuz between your description and Verslagens hydraulic/mathematical A nalysis, it's not really speculating.. There is no way that is a good idea. You Might get away with it, but it's all risk and no reward.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by MMRanch on 11/12/15 at 21:54:07

Heck ! If the motor is running using my fuel it needs to be taking me somewhere ... not sitting there warming up anyway ! ;)

That sounds like good science Dave . 8-)

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by justin_o_guy2 on 11/12/15 at 22:07:19

I think Row is onto something.
Ohh, ehh, I meant On something.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by justin_o_guy2 on 11/12/15 at 22:53:41

Another potential cause for loss of oil to the top right end...
When people pull the head cover and don't get the sealer thin... Cuz a big gap between head and cover equals a sloppy cam clearance, equals less oil to pump up the hill.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by Kris01 on 11/13/15 at 15:45:39

2C3E2C3E33202F2229610 wrote:

Heck ! If the motor is running using my fuel it needs to be taking me somewhere ... not sitting there warming up anyway ! ;)

That sounds like good science Dave . 8-)

'zactly!

I never warm up my vehicles anyway. They get warm enough as I'm driving down the road.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by Steve H on 11/13/15 at 17:45:50

I will give a few seconds of warm-up in cool/cold weather
Always sitting on the bike when I do it and just enough to warm the cylinder and valves a little.

My bike doesn't stumble or miss after a few seconds choked and on fast idle. And, I do want a little oil pumped around before taking off. I'm a firm believer in a little circulation time then off you go. Let it warm up while riding. Just take it easy for a mile or two.

Title: Re: Camshaft/Rocker damage - sidestand issue.
Post by Dave on 11/14/15 at 03:46:37

I am on my bike and the kick stand is up when I start my bike, and I hold the throttle at a fast idle for about 30 seconds to a minute, somewhere around 2,000 rpm. The bike is level, and the fast idle gets the oil pressure up enough to get some oil up to the head and cam.