Adding ZDDP to engine oil?

[XS650D]

I have a bit of a knock in what sounds like the bottom end. Stranglely the noise will stop
if on the side stand or once the bike is good and hot after say 10 minute ride.
Thinking there may be a lil wear in the crank end bearings. I run 20/50 Regular oil
Decided to give the ZDDP additive (on order) and see if it quiets it down on cold starts and run-in.
Cheap fix if it works. How much should I add, should have in a few days otherwise the bikes running great!
ps: almost ordered the LiquMoly for motorbikes but the ZDDP is tried and proven especially on the
older cars,no cats to screw up.Dont see a down side unless I add to much!!

 

[Jim]

I wouldn't recommend it. Our wet clutches don't like oil modifiers.

 

[TwoManyXS1Bs]

I have a bit of a knock in what sounds like the bottom end. Stranglely the noise will stop if on the side stand or once the bike is good and hot after say 10 minute ride.
Thinking there may be a lil wear in the crank end bearings...

Interesting clues. You may want to probe around with a stethoscope, see if you can locate it first.

I've been running Valvoline VR1 20w50 (high zinc), a gggGary recommendation. Oil pressures better than conventional oil, clutch works fine. An old metallurgy book of mine discusses the contemporary ('50s-'60s) use of ZDDP as an important cushioning additive, for hardened parts that *bang* on each other, like the valve train.

A common topic in the vintage auto forums. Could dig thru those for recommended amounts...

 

[XS650D]

The good news is it goes away when warmed up good, the bad news is a knock is never a good thing!
Will be interesting to see if the extra Zinc makes any difference.I think I read that 5Twins adds it on every
oil change and I highly respect his opinion, he has not reported any issues running it.

 

[grizld1]

Molybdenum additives will condemn your wet clutch to a lingering death. I've been using ZDDPlus for years; one bottle per gallon of oil, as recommended. I doubt that it will do anything for the low end; zinc diethyldithiophosphate was used to reduce rocker and cam wear in motors with rocker-and-tappet valve trains.

 

[gggGary]

Yeah one of those why use an additive if you can buy it already in the oil? At a ratio marketing, the penny pinchers and the engineers agreed on.

 

[grizld1]

Here's one guy's reason why, Gary. I use cheap 15W/40 diesel oil and change it often, and the oil manufacturers have cut ZDDP levels in that stuff.

 

[gggGary]

True that grxld.

 

[XS650D]

Im using Spectro 20/50 Dino Motorbike oil, does not list any zddp or zinc on bottle alough
there may be some in it, u may be rite Griz but cant hurt to try. Was thinking of testing a strait 50 weight
oil, what are your thoughts on that

 

[xjwmx]

I have a bit of a knock in what sounds like the bottom end.

A good mechanic told me a rod knock will happen all the time; not go away under some condition.

I would check what I could visually -- pull both case covers and use the starter to check for any visible wobbling of the crank. Do something to keep it from starting like that... Check for side play in the crank. Go through the clutch. Also check cam chain tightness. The sounds it can make change or go away with heating and oiling, and it can change sound if the bike is leaning, esp. if the rubber on the front guide is gone. Both of which you describe.

 

[Jim]

Well... my bad. I thought the stuff you were referring to was one of them super slick modifiers. Guess I shoulda did some googling first....

 

[XS650D]

I pulled both side covers, pulled clutch apart also put some vise grips on rotor nut, no play or anything
jumping out at me,definately not top end, may have to pull motor in winter and split.One of those things were
may be able to ride forever and no issues OR something grenades while im cruisin down the road tomorrow!

 

[XS650D]

Whats involved in checking the rubber on the front guide, can it be done with motor installed.
I checked the cam chain free play, its definitely not that . If it is the front guide whats the worst case
scenario if I leave it alone?

 

[xjwmx]

You'd think if the front guide rubber was off, you'd notice a sudden change in cam chain adjuster looseness, but I'm not sure of that. Mine was off and I never suspected it until I had the engine apart to replace a wonky crank. In the weeks leading up to it I did notice a faint whine, but I'd heard similar things from time to time 40,000 miles ago too.... Figured this time it was coming from the separating crank. There was a pretty good gouge into the aluminum part of the guide and the rubber was sitting there propped beside it.

 

[XS650D]

Separating crank!!! Wow! I always read these bottom ends were bullet proof!

 

[XS650D]

Borrowed a Steth but really hard to tell were the noise it coming from theres so many areas that
u can hear it from.Worth mentioning is if I raise the idle to 1500 or more the knocking stops, weird!

 

[xjwmx]

Might not be extremely uncommon. Two or three guys on here have had the problem. There's a story on here or somewhere about a guy who goes to the service desk says there was a thud from the starter and now... and the service desk guy was able to finish the rest. The cause is sometimes a nice energetic starter that catches funny somehow. That's what happened to me. Big clang from down there on starting, and thereafter separated crank.

 

[XS650D]

Just listened to an old tube video of a guy from Quebec with a 78 with exactly the same sound knock but louder than
mine and but did not go away when warm BUT when he pulled engine apart it was the front chain guide, the plastic or rubber had partially
come away from the metal. As u have mentioned above, thats most likely the problem. Its probably starting to delaminate
and once the oil gets warm it quiets down.Looks like an engine tear down is in order unfortunately but will be holding off till the winter.
Thx all for your advise. Now I have to decide if I will tackle this myself or have it done for me $$$

 

[TwoManyXS1Bs]

Try probing the front tensioner bolts. Both before, and after the sound appears.

 

[XS650D]

Crap,should have tried that! Gave unit back, what about with a long screw driver TM?