Next Engine, please

[Crazcnuk]

Looks like I am going to have to pull the engine out of the 80G.

It is making some really strange noises.

It has full power, good economy, runs smooth, etc. But it has a 'rattle' that I can't think is ok to ignore.

It usually starts to 'rattle' at ~4000rpm, but only under acceleration. If I am am coasting or slowing down it does not make the noise.

Once it has been started, I can get it to rattle, any time I add throttle at almost any speed 2500-5000rpm. However, it comes and goes. Sometimes it will do it sometimes it won't

After 5000 rpm or so it stops, and sounds ok after that.

The rattle sounds like a really loose lifter on a chevy smallblock. I set all the valves the other day, checked the valve train, cams etc.

Also the valve train is much noiser than usual, expecially when cold. I adjusted the cam chain, once and it went away for a day or two, but came back, and now adjusting the chain does nothing.

This is the engine I did the top end on last year, it ran great all last season, and at the start of this season.

ideas?

[WMarshy]

Have you tried and mechanic's stethoscope to try and find the source? Could it be as simple as the exhaust hitting the frame or engine mount? I would try the stethoscope before I went and tore anything apart...a lot chaper and quicker...

[XS1100 Newbie]

Make sure your tensioner bolt is not stripped, and actually pushing the guide.

[bikerphil]

My special does that, but only when warm. Maybe disconnect and plug your vacuum advance line and see if it goes away, or retarding the timing, JAT, My noise goes away if I retard the timing, but then it has no grunt.

[Crazcnuk]

If I could figure out how to lay on the bike while driving it down the highway, the stethescope may work well, however I can only get it to make the noise when it is under load, and actually accellerating.

I can't get it to do it on demand, exactly, but pretty close.

I don't think this is the detonation issue. My bike has had that all along. It sounds like a rock polisher at cruising speeds.

This is something new. it just started a couple of weeks ago.

Just for a lark, can anyone describe what it sounds like if you have a piston pin retainer missing?

[Pat Kelly]

Sounds to me like the primary drive chain is slapping the case.

[motoman]

You'd be amazed where a weak vacuum diaphram rattle noise will carry too! JAT, had it happen with mine sometimes when cold after starting then again when hot at times, was erratic but mostly under a bit of load.....sometimes, sometimes not, just got more noticable.

[Crazcnuk]

i will certainly give the vacuum adv a look over.

However, unhooking the vac adv should not bother your power at all. In fact when I drag race the Monte Carlo I unhook the vacuum advance, as do most drag racers, if they have the system hooked up at all.

Vac adv only advances your timing when you let the throttle OFF. It is purely for fuel economy and has nothing to do with building power.

Doesn't really sound like chain slap, and it's a brand new chain >10,000kms. But it could be, the other noise sounds like the chain to me.

[scalded dog]

Went thru this for months, between 60 and 65, what I cruise at most of the time, I heard this rattle, bought a cam chain, but didn't put it on because the bike still ran good, except when I would "WOT" it would stall shoot out a ton of black smoke, then it would take off, finally it got to where it would stall and wouldn't always take off like before. after getting beat by a harley, I started looking harder getting ready to do what I had too. I've had this bike for 10 yrs. so I know it inside and out. I first started checking timing, come to find out, the plate that swivels had got worn, and wasn't swiveling very smooth, therefore the advance was not working right. replaced that. Noise gone, and ain't no Harley gonna touch it now. LOL. Later 'Dog

[Crazcnuk]

I have already checked and lubed the advance system. It was sticky, but did not change the noise.

I also took off the clutch cover and checked anything else I can think of, short of going into the motor.

The cam chain was new last summer. As many here know, I have no trust or love for the cam chain tesnioners on these bikes!

[cywelchjr]

I have already checked and lubed the advance system. It was sticky, but did not change the noise.

I also took off the clutch cover and checked anything else I can think of, short of going into the motor.

The cam chain was new last summer. As many here know, I have no trust or love for the cam chain tesnioners on these bikes!

I still think you need to disconnect the plug the vacuum advance and see if that makes a difference (I know, I need to take my own advice), you will know one way or the other, either it IS the detonation problem (the TSB says it sounds like a rod knock, not a lifter) or it's not and it's something else.

[Crazcnuk]

What I don't understand is why the 'knock' would start now, after 4 years, if it was a detonation problem.

On the upside I finally got rid of most of the noises the fairing used to make, maybe this is just what the XS sounds like!

[XSokieSPECIAL]

Craz

It's probably a long shot but if you remember when i first got my bike I had a similar problem.

I found that the cam bearing caps had come loose. JAT

[Pat Kelly]

You said it's a new chain. I wasn't talking about the cam chain. I was thinking it's the wide Hyvo chain.
The fat chain from the crankshaft to the clutch/trans input shaft.

[Crazcnuk]

I checked the cam caps when I set the valves, as that was one thing I thought it might be too.

As for the primary chain, I don't think its possible for it to hit the case, since it sits above the oil pan. I really don't think it can streatch that much in the mileage I have either.