Is this engine chatter normal with auto CCT?

[BA80]

The driven side of the chain, at the rear of the engine, will stay tight when the engine is running thus the timing will be correct.

That is how the auto tensioner adjusts. It's the slapping of the slack side of the chain, the front, that causes the manual adjusters to slip. The auto tensioners are designed to go just one way and when they get a chance to go, they do. When the slop moves inward.

That's what I don't get about these people worried about excessive wear on the adjuster slipper. When the engine is running and the manual adjuster is adjusted properly,there is constant pressure on it anyway and if it's not adjusted properly it's like 10,000 little hammers beating on it all the time.

I don't get that logic.

[DGXSER]

Two things here.

A stretched chain will allow the engine to go slightly out of time, not enough to crunch valves but enough the dots will not be exactly aligned, and enough it could effect timing, and maybe fuel consumption. I would classify it under possible but not probable myself as to the fuel consumption, it will definitely allow the timing to move if ever so slightly.

As to the Auto CCT, it moves in steps, not an infinite amount of settings liek the stock tensioner, but definite steps. So if your cam chain stretch is somewhere between step 5 and step 6, it has that little bit of movement in between it can "slap" around. How much is that? Is it enough to cause any real issues? My best inclination is it is not enough to matter or it seems it would have shown up as a design flaw of all the bikes that use it stock.

[blkryno]

I was looking through some older threads and found the one on the supposed XS1000 in 1977 that turned out to be the XS1100. Anyway I was reading some of the cycle magazine articles from 1977 about the bike and on their test ride they found that the cct had loosened with an audible sound from the cam chain and needed adjustment after only 500 miles. That was with a new bike. (like mine was. ) Just thought I'd throw that in.

blkryno

81 11 SH (83 Venture cct )
79 11 SF (83 Venture cct on the shelf for it.)

Semper Fi

[gareth]

I did the mod a few weeks ago. I did notice that the engine seemed a bit noisier on top after fitting the venture CCT. One thing that I definitely noticed was when I was goofing around with setting the timing. The engine definitely doesn't like being turned the "wrong" way when the automatic tensioner is fitted. I was trying to get an exact position for TDC with a degree wheel and when I turned the engine "backwards" a fraction, as I got close on the wheel, I heard the chain gathering up inside the engine..
I could be wrong, but the constant tension on the camchain makes going with the normal engine direction more important if you are rotating the engine by hand with a wrench on the timing wheel..

[3Phase]

Greg ... are you serious? Really?

As the cam chain and gears wear, the intake camshaft starts to lag behind the crankshaft and the exhaust camshaft starts to lag behind the intake camshaft. That is hard wear that can not be changed by adjusting the cam chain tension. It usually takes a long time but it will happen more quickly if the cam chain is kept too tight or to loose.

The cam chain is a driven spring/damper, a Slinky, basically, with hardened links instead of coils, that is driven by the crankshaft and damps some of the oscillations caused by the valve springs loading and unloading the camshafts.

You can see what the cam chain does by putting a cylinder head on a workbench and supporting it with wooden blocks placed so that the valves can't hit anything and bend when they open. Use an open end wrench to turn one of the camshafts by the hexagonal flats cast into the camshaft next to the timing boss.

The valve springs load the camshaft lobes and the camshaft is difficult to turn until a lobe goes past maximum lift on a valve, then the camshaft snaps forward when the valve spring closes the valve and moves the camshaft out of the way by pressing on the back of the lobe.

A good cam chain with the correct tension prevents that from happening because the gears are all held in more or less perfect time and place. The two camshafts and the crankshaft can not move independently of one another.

With to much slack in the chain the camshafts start to be able to snap forward slightly instead of being restrained by the cam chain, then the chain pulls tight again and continues turning the camshaft.

It does not matter if the slack is caused by valve train wear or by incorrect tension, the cam chain is not doing its job:

Boing. SNAP! Boing. SNAP! The chain is loose and wearing out. Boing. SNAP! Boing. Power and gas mileage are down. SNAP! Boing. SNAP! Boing-oing-oing-oing! SNAP! Someone or something tries to leave the bike at a high rate of speed headed east and staying south.

[BA80]

Yes, I am really. I didn't think we were discussing cam chain and cam gear wear, I thought we were discussing cam chain tensioners and their effect on fuel consumption and performance.

The wear factor would be another thread.

Guess I missed something.

[3Phase]

Yes, I am really. I didn't think we were discussing cam chain and cam gear wear, I thought we were discussing cam chain tensioners and their effect on fuel consumption and performance.

You're right, Greg, a loose cam chain has very little effect on engine power and fuel economy. You can't tell it's loose by how the engine runs and how much fuel it uses; especially in an old, feeble, rice-burning lump that only turns 8,500 RPM and did the quarter mile in less than 11 seconds off the showroom floor. What could possibly go wrong when the cam chain is a little loose and the camshafts don't stay in time while the cam chain is whipsawing the cam chain guides[1] into oblivion? Certainly not the cam chain tensioner!

Only a worn cam chain and gears can cause problems with basic engine timing that would affect engine performance and fuel consumption rates. You should probably have a quiet word with some folks that disagree ... but go ahead and finish your beer, no hurry:-

Gear Drive

The wear factor would be another thread.

Guess I missed something.

Greg, just have another beer and don't worry about it! Sheesh!

Just, please, please, let me have that miraculous cam chain and tensioner you have that doesn't allow your engine go out of time, lose power, or consume more fuel when the tensioner is out of adjustment. I want to study it before I send it to Pete Jackson!


1: Hard vulcanized rubber is good for the engine. The microscopic rubber particles in the oil cushion the connecting rods; soothe the savage plane main bearings and noisy straight-cut transmission gears[2]. Cam chain guide debris in the engine oil is almost as good, and certainly much less expensive and difficult to apply, as the so-called anti-friction coatings put on by those morons that patronize custom engine rebuild shops. If more people knew about the benefits of the hard rubber dispenser on just one of the handy cam chain guides that is already bolted inside the engine! those guys would be out of business in less time than it takes to flatten a camshaft lobe or spit a valve clearance adjustment shim!

2: Rubber particles in the oil might actually be good for the straight-cut gear noise but the rest of footnote 1 is a complete crock of recursive kookery[1]!

[BA80]

You're right, Greg, a loose cam chain has very little effect on engine power and fuel economy.

At least we seem to agree on that.

Greg, just have another beer and don't worry about it! Sheesh!

Just, please, please, let me have that miraculous cam chain and tensioner you have that doesn't allow your engine go out of time, lose power, or consume more fuel when the tensioner is out of adjustment. I want to study it before I send it to Pete Jackson!


1: Hard vulcanized rubber is good for the engine. The microscopic rubber particles in the oil cushion the connecting rods; soothe the savage plane main bearings and noisy straight-cut transmission gears[2]. Cam chain guide debris in the engine oil is almost as good, and certainly much less expensive and difficult to apply, as the so-called anti-friction coatings put on by those morons that patronize custom engine rebuild shops. If more people knew about the benefits of the hard rubber dispenser on just one of the handy cam chain guides that is already bolted inside the engine! those guys would be out of business in less time than it takes to flatten a camshaft lobe or spit a valve clearance adjustment shim!

2: Rubber particles in the oil might actually be good for the straight-cut gear noise but the rest of footnote 1 is a complete crock of recursive kookery[1]!

This dosn't seem to have ANYTHING to do with the original subject Scott and it seems to countradict your first statement. What exactly ARE you trying to say?

[3Phase]

At least we seem to agree on that.

No, we don't. I can tell when the cam chain is loose because the engine loses power and fuel economy starts to drop. Oh, yeah, and there's some noise, too.

This dosn't seem to have ANYTHING to do with the original subject Scott and it seems to countradict your first statement. What exactly ARE you trying to say?

That you didn't understand the explanation and you still believe that a loose cam chain does not do the same thing as a worn cam chain but it's not important so have another beer and go loosen your cam chain tensioner because it's probably too tight and is destroying your engine by maintaining its base mechanical timing and thus its original power output and fuel efficiency and I am going to be so rich when Pete Jackson sees your cam chain and tensioner!

[BA80]

Well, I can see that you are stuck in a loop of circular logic so there is no more discussion.

Have a nice day.

[crazy steve]

A chain-driven cam is certainly not the last or best word in valve timing accuracy. As Scott said, a loose or stretched cam chain will have an effect on both performance and fuel economy. Even one that's properly tensioned and in good condition will have 'errors' in it's timing depending on it's harmonic frequencies, which is why noisy, costly gear drives exist.

Back in the mid-to-late 60s, Fords' still-born 427 SOHC NASCAR Hemi-killer ended up at the dragstrip. One of the things they found was that the right bank cam needed a few degrees more advance, due to cam chain harmonics and the effects of the tensioning system; and that was when everything was right. Add in a loose chain, and the effects become magnified.

So why do they still use chains? Main reason, cost. Another is the transmission losses through multiple gears; this is the same as the power losses through the XS shaft drive vs a chain drive, although not to the same extent. But when ultimate reliability and accuracy are the goals, you'll find gear drives; go to any racetrack and the purpose-built motors will very rarely have chain-driven cams...

[BA80]

Thank you Steve.

I am fully aware of how the timing chain and gear systems work as I built sprint car engines back in the day. The gears were the choice back then because of reliability issues with the chain but many still used it because of fianancial issues, as you said.

Those engines ran WITHOUT a CCT (SBC) and the only thing that affected the valve timing was a worn chain or gears, which was a double roller rather than the single roller we have, which didn't happen very often because if the wear was that bad it tended to grenade.

The wear on a roller chain is pretty insignificant unless it's run out of oil.

[3Phase]

Have a nice day.

LMAO! Greg, lighten up, man! You have a nice day, too, OK?

Those engines ran WITHOUT a CCT (SBC) and the only thing that affected the valve timing was a worn chain or gears

Swing and a miss! There are plenty of aftermarket timing chain tensioner kits available for the SBC and timing chain/gear wear is not the only thing that affects valve timing.

Align boring the block moves the centerline of the crankshaft closer to the camshaft so the stock length timing chain will be too long. To correct the base timing there are some rather expensive timing sets available with timing chains hand-picked for length that fit on hand-lapped, adjustable, gears. There are adjustable camshaft gears available for XS11s but good luck hand-picking a timing chain.

Moving back to motorcycles with overhead camshafts: Harley's Twinky has ACCTs and a tendency to eat cam chain guides but there is a gear drive available that eliminates the problem and makes the engine run better because the camshafts stay in time. There is nothing like that for the XS1100.

Heck, if someone just removes the timing gears from the camshafts in an XS it's 50/50 they'll put them back on correctly.

[James England]

hi james,

for any reason ur not happy with the self tensioner,
u could always tap a bolt into the center of the oem tensioner,



i wasnt the 1 that came up with the idea, but works great, ive had it
in for years now, the side bolt doesnt do anything except preventing oil
from leaking. jat.

Clever. Now, if the automatic CCT sounds like a Bren gun, I'll be doing that idea. Thanks for that!

[blkryno]

I'm not up on all the progress that has been made by Yamaha over the years with the cct's. Is there any info that they went back to the m-cct's or redesigned the a-cct's do to excessive wear issues ?

blkryno

81 11 SH (83 Venture cct, Tkat fork brace on order.)
79 11 SF (83 Venture cct on the shelf for it.)

Semper Fi