rattle after kawa 691v warms up at fly wheel area shes super quiet when first started

[cpurvis]

cpurvis,

Respectfully,

Effectively, once the lash is loose, it does cause the valve not to open as far and for those that doesn't understand that, lift. Duration is a part of timing according to the amount of lift and when it opens and closes (duration) is a part of timing however not related to crankshaft relation to camshaft. Only in relation to the valve opening and closing relative to the piston placement and dwell time over top dead center.

I ground a lot of camshafts, crankshafts and valve relationship opening is what we're talking about. If the valve doesn't open soon enough (far enough) the compression can lock the engine until the compression can leak down enough for the engine to start. But then, you and I know that. Perhaps the fella with the valve lash problem may not.

Max

Also respectfully, cam timing is defined by the angle between cam lobe centerline and either TDC or BDC of the crankshaft. Engines with variable valve timing can change this angle; fixed cam timing engines, such as lawnmower engines, cannot.

You're right in that excessive valve lash can delay the opening of a valve and cause it to close prematurely, but the angle between those two events is defined as 'duration.' It has nothing to do with cam timing. Peak lift occurs at the same fixed place, regardless of how much or little the valve lash it has. It will be reduced if lash is excessive, increased if valve lash is less than specified. But it occurs at the same, fixed point defined by how the cam is timed to the crankshaft.

The last thing we will discuss is the difference between intake centerline and lobe separation angle. These two terms are often confused. Even though they have very similar names, they are very different and control different events in the engine. Lobe separation angle is simply what it says. It is the number of degrees separating the peak lift point of the exhaust lobe and the peak point of the intake lobe. This is sometimes referred to as the "lobe center" of the cam, but we prefer to call it the lobe separation angle. This can only be changed when the cam is ground. It makes no difference how you degree the cam in the engine, the lobe separation angle is ground into the cam. The intake centerline, on the other hand, is the position of the centerline, or peak lift point, of the intake lobe in relation to top dead center of the piston. This can be changed by "degreeing" the cam into the engine. Figure 1 shows a normal 270 degree cam. It has a lobe separation of 110°. We show it installed in the engine 4° advanced, or at 106° intake centerline. The light grey curves show the same camshaft installed an additional four degrees advanced, or at 102 degrees intake centerline. You can see how much earlier overlap is taking place and how the intake valve is open a great deal before the piston starts down. This is usually considered as a way to increase bottom end power, but as you can see there is much of the charge pushed out the exhaust, making a less efficient engine. There is a recommended intake centerline installation point on each cam card, and it is important to install the cam at this point. As far as the mechanics of cam degreeing, COMP Cams® has produced a simple, comprehensive video (part #190) that will take you step-by-step through the process.

http://www.compcams.com/Pages/416/valve-timing-tutorial.aspx

 

[mhavanti]

cpurvis,

You and I are in the know of how timing is arrived during the 720 degrees of turn for a crankshaft relative to the camshaft, I'm betting others reading our comments do not. At least our fellow readers will now have a better understanding of the camshaft, crankshaft, valve opening points and closing points. Add in lobe centers, lobe spread and we can go on and on.

Good hearing from you. Keep up the good work.

Max

 

[cpurvis]

Same to you, Max! It's been a pleasure.

 

[7394]

I'm using Shell Rotella T 15/40. It is a mid continent oil that will run in anything and save the motors over pretty much anything else on the market.

My family was in the patroleum industry beginning in 1961 and stayed involved in it until 2004 when we all retired. Shell Rotella T will clean up the inside of an engine and preserve the cross hatch on your cylinders longer than all the other oil on the market as evidenced by many independent laboratories, even to this day including synthetics. I don't run synthetics and if a person wants to pay the price for it, I say go for it. Will it make your engine last longer, answer is no.

You're changing back to the 30W is most likely coincidental to the oil consumption meaning the rings finally seated most likely. Perhaps not, but, as a machinist engine builder, that is my guess. The 30W will heat the engine more quickly due to the heavier weight while the engine oil is cold. That in itself can seat the rings if they were close to finding their home.

Hope your little kawi lasts for at least 1500 hours. Keeping the valves adjusted will help.

Max

Max-
For the first 2 years of ownership or since I bought it new, I run the 30wt, & never used a drop. When I switched to the Kaw 10w-40 is when oil consumption was evidenced. And only put 15.4 hours on with that oil in mine, this year.
So no not the rings finally seating. I now only have 79.9 hours on it.

I worked in Machine shop at nights many years & still build Harley motors.

Might try the Shell 15/40 next oil change.

 

[cpurvis]

This may be unrelated but I've had consumption problems with 10w-40, too. I had a little 4 cylinder Ranger pickup whose manual said to use 10w-40, which I did. It usually went through a quart every 800 to 1,000 miles. By mistake, I substituted 5w-30 and the oil consumption vanished.

"C" class oils (Rotella, Delvac, Delo, etc.) are required by diesels but work well in gas engines which specify "S" oils as well. Apart from viscosity, which is usually 15w-40, they are very high detergent, with very high TBNs (total base number, with "base" being the opposite of acidic, i.e., alkaline). They do a heck of a good job keeping engines clean.

 

[7394]

Very interesting, one would think the opposite. Thanks for posting this.

I mow normally 30-35 minutes for my place (not counting occasional double mows) & for that quick 1 mow, my cold dip stick used to drop 1/8 inch in that short time.

I would prefer to run a multi-grade to get the oil everywhere quickly after sitting 1 week since last mow. But it won't be anymore 10w-40 for sure.

I'm familiar with the Diesel oils.