Mechanical Help! Mechanical Noise - TC88B

[banquo]

Originally Posted by Scotty

Yes it can wear on the splines on the crank.
And it does sound like a heavy clunk.
The loose comp nut the other week also sounded like a clunk and at times sounded like it was coming from front cylinder.
Either way i dont think you should just leave it, their is obviously something wrong and eventually whatever it is is gonna let go and it might be with a big bang causing all sorts of damage.
If it were me i would have to find it.

Thanks for that Scotty; I am of the same mind, and wouldn't be happy until I knew for certain. I'll get the Service Book out, and see what's involved in getting to it. Assume the best way would be to remove the primary chain, comp sprocket etc. I already have the primary locking tool, so guess all I'll need is a slimmed down 1 1/2" 6 pointer to get the comp nut off.... Doing the diagnostics is the most difficult bit, isn't it? Easy enough to get stuck into a job, when you know exactly what it is you're trying to do, but I still remember replacing the transaxle bearings on my Imp back in the seventies, only to discover that it was a wheel bearing that was droning away, even though there was no play in it...

[banquo]

Originally Posted by the_monster

post number 2 on that link is interesting too

Hoisted with my own petard... ?

C'mon, it was my first thought this time too, but seems as tight as it can be...

[banquo]

Originally Posted by Phil

Just to throw another turd into the pot.

Sorry Jake. Over the hundreds of engines we see, there are two other things that spring to mind vis a vis the front cylinder, though rare.

Evos had a habit of the front rod (Big End) going slightly oval & knocking.

Rarely seen on a Twin Cam unless it has been well thrashed.

Also on well thrashed Twin Cams we have seen the front little end or piston pin bushing go bad. Fairly easy to replace.

Your symptoms could be the latter.

I am still thinking that you may have a tired lifter though.

I'll take as many turds as you can throw Phil, because I want to find and sort this.

I've had this bike since new, so I can be sure it's never been thrashed, ever (barring during dealer services in the 1st 2 years, but that seems unlikely). Rarely over 3000 rpm, and never over 4000.

Big end was in the possibilities basket from the start, but after thinking about it a bit more, it seemed less likely. I've never had one go on anything I've owned, but seem to remember it tends to be worst when lugging under load, whereas this clunks only at slow tickover. I haven't heard any clunks under load, although it's fair to say it would be hard to hear with all the wind and exhaust noise...

Small ends I've heard on other, non-Harley, motors, and they always sounded more like a rattle; quite high pitched, and not like this clunk. True?

What does the lifter sound like? I'm imagining it would sound like a loose tappet on a non-hydraulic tappet system. A rattle again. Or is it different on a Harley? Silly question, but if it is a lifter, how is it sorted? Is it the lifter itself that wears, or the bore it runs in?

The rotor sounds like a good call if lifters are out, because my subjective impression, from very limited opportunities to listen to it, is of something heavy and loose clunking about when the engine is hunting.
I'll definitely do the screwdriver stethoscope thing, and see if I can tie down where it's coming from.

Finally, to all of you, I really appreciate all your suggestions. Hopefully we can get it identified and sorted out, and it might be some help to someone else too.

Glad it's the end of the season too...

[banquo]

Originally Posted by the_monster

I'm still on the lifters especially as it goes away once you oil is up to temperature and the flow rises.

Still does it on the hot engine Andrew - seems more slow engine speed related than oil pressure related, although I'm not sure of that. It's not noticeable when hot, because it settles immediately to a smooth tickover, Same applies when it's cold, with the choke right out. Might get a single clunk hot or cold when it first fires, but when on fast idle, it's quiet. When the motor starts to hunt as it warms up, the clunk appears with the engine stutter, hence the idea it's the momentum of something heavy and rotating not keeping up with the hunting. It's really difficult to explain 'funny noises' but hope you get the idea...

[the_monster]

I've the clank when starting on my 103 and that has been used (30k+ miles) and abused (up to 6k rpm) as they say, and it has gotten a bit clattery when the oil has got thin on a bloody hot day and I've been running at the throttle stops

what speed do you tick over at ? again if it's too low you might not be getting enough flow to pump them fully - just think of brit bikes and the dreaded red light flickering at the traffic lights, give it a blip and the light went out

[Tony G]

i've heard if the engine idles less than 800 rpm the oil pump isn't doing its job on an EVO ? what's your idle when you here the noise ?

[Scotty]

Good luck with it mate, let me know what you find, always good to store it away in the memory (i write it down these days )

[Phil]

Just an FYI Jake.

The correct way to take care of the compensator is to first remove the fastener bolt.

Due to Loctite etc, it shouldn't be just tightened.

First remove the large Nut/Bolt whatever you want to call it.

Using a wire wheel on a Dremel (or whatever you can figure out) remove all the Loctite & dirt to make both threads TOTALLY clean.

Apply red Loctite & torque as per the manual.

As Scotty may well be right you may want to remove the Rotor to inspect the rotor splines.

Either way, re-installing needs to be done as per the above.

[banquo]

Thanx mate; I have the new tightening instructions too (torque + tighten a few degrees more).

[banquo]

Some progress - got a loan of one of these:

Started up the motor, and tried the primary side on slow tickover (reduced to 500 rpm, which is a lot slower than normal.
Clack, clack, clack heard through the primary cover.
Try again on top of the cam box, and this time it's:
CLACK, CLACK, CLACK.
You can feel the vibration every time it does it.
Increase engine speed, and it goes away. With the stethoscope, you can tell it's really gone, and not just getting drowned out by the exhaust noise.
Great piece of kit!
So, it looks like Phil's original thoghts were right enough, and it's a lifter after all.
Next, find out what's causing it, and do whatever's required to correct it....
Is it just the lifters themselves that get worn, or could there be an issue with the oil supply?
I guess I can change the lifters from the top of the cam box, without removing the cam plate, if I cut the pushrods and replace with 2-piece adjustables?